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CHOLOGICAL MAGAZINE. 
IDIDCUMIDIN We WOILE WALL 


JANUARY—DECEMBER, 1910. 


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Vv THE 


GEOLOGICAL MAGAZINE 


On 


Monthly Journal of Geology: 
Mhih GhOwoGis T? ”. 


NOS. DXLVII TO DLVIII. 


HENRY WOODWARD, LL.D., F.R.S., F.G.S., F.R.MS., 


LATE OF THE BRITISH MUSEUM OF NATURAL HISTORY; PRESIDENT OF THE 
PALMONTOGRAPHICAL SOCIETY; ETC., ETC. 


Proressorn J. W. GREGORY, D.Sc., F.R.S., F.G.S. 
Dr. GEORGE J. HINDE, F.R.S., F.G.S. 
Sre THOS. H. HOLLAND, K.C.1.E., A.R.C.S., F.R.S. 
Prormsson W. W. WATTS, Sc.D., M.Sc., F.R.S., V.P.G.S. 
Dre. ARTHUR SMITH WOODWARD, F.R.S., F.L.S., Suc. G. Soc. 


AND 


HORACE B. WOODWARD, F.R.S., F.G.S. 


NEW SERIES. DECADE V. VOL. VII- 


JANUARY—DECEMBER, 1910. 
2Z1S2S | 
LONDON: 


DMG COn LID 37 SOHO “SQUARE, W. 
1910. 


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LIST OF PLATES. 


PLATE FACING PAGE 


I. Olivine Nodules in Basalt, Derbyshire : : : ’ : 3 
II. Olivine Nodules in Basalt, Derbyshire eK c : ; 4 
III. Chalk Polyzoa (Bryozoa) . ‘ : : : : Sabie 5 
CPE Godstorritel’ Morbihan? a Per, POSS oy) lle Nae 
V. Pleochroic Halos around inclusions in minerals . : ek) 
VI. Sculpturings of the Chalk Downs : a gs , ; pete) 
VII. Fossil Plants from the Bristol Coal-field ; d : 3 GE 
VIII. Chalk Polyzoa . c ‘ : : 2 ; : ‘ Sa ea 
IX. Coast of Etel, Morbihan ange )Y/ 
X. Sections of Rocks from Etel, Brittany ‘ , : : 5 Lio 
XI. Rock-sections from pre-Tertiary Dyke, Usway Burn . A > Lie 
XII. Skeleton of Peloneustes philarchus, Peterborough : i 5 ile 
XIII. Striations on Glacier Granules . : ; ; ; i . 114 
XIV. Chalk Polyzoa . : : : : : : ; . . 146 
XV. Archimylacris (Ltoblattina) Woodwardi, Bolton, sp. noy. . 5 il 
XVI. Trinueleus from Dutton Shales . : : : P é . 214 
XVII. New Crustacea from Dufton Shales. : ‘ , : Ss 
XVIII. Porphyries, Huelva, Spain : : : : . 228 
XIX. Navis Valley in North Tirol ; 4 : : : : . 246 
XX. Navis Valley in North Tirol . : ; ; é : . 258 
XXI. Chalk Polyzoa . : : : : : : : af 2260 
XXII. Portrait of the Rev. Prebendary William Henry Egerton, M.A., 
F.G.S. : : : 2 : : : 287 
JIT. New Fossils trom the Dutton Shales . : : é ; 296 
--XIV. New Fossils from the Dufton Shales . ‘ : ; : . 298 
XXY. Wind-worn Pebbles . ‘ ‘ : : : ; é . 302 
XXVI. Stone from wall, Sutton-on-Trent Church, Notts., and Silt in 
Prieska Ravine, Orange River. é : A : pill 
XXVIII. Chalk Ammonoids from Lincolnshire . 5 : ; ‘ . 3848 


XXVIII. Wind-eroded Rocks on the Coast of Mull . : : 5 5 aS: 


vi ~ List of Plates. 


PLATE FACING PAGE 
XXIX. Wind-eroded Rocks on the Coast of Mull. : : : . 355 
XXX. Chalk Polyzoa . ; , ; : F 5 : : . 392 
XXXI. Pebbles from Desert of Egypt showing action of wind-blown sand, 394 
XXXII. ‘ Dreikante,’ showing wind-cut curves ‘ ; ‘ P . 396 
XXXIII. Eocene Fishes from Egypt é : : : ; 5 . 405 
XXXIV. Fossils from Bembridge Limestone, Creechbarrow Hill 5 . 439 
XXXY. Superficial Deposits at the Foot of the Cheviots . : : . 458 


XXXVI. New Chalk Polyzoa . : : ; ‘ 4 : : . 483 


LIST OF ILLUSTRATIONS IN THE TEXT. 


; PAGE 
The Etel estuarine area E : t : 3 5 : : . i 7 
Etel, section of raised beach : F é : : ‘ ; : : 8 
Riviere d’Etel below Eteland La Magoire . . . . . . . 10 
Etel, terraces at mouth of the river ; : : ; : : F Oe TT 
Complicated and sinuous Dry Chalk Valleys, North Downs . : : 5 6 
Dry Chalk Valleys of the ‘Seven Sisters’. : : : : ; aol 
Three figures of Sphenopteris ovatifolia, sp. nov. . é 5 . ‘ eo 
Two figures ot Lepidodendion Glineanum, Kichw. . 5 , : 6 o 6B 
Sketch-map of Carboniferous Limestone near Llantrisant Station . : 5 Be 
Submerged forest and peat beds, Plougasnel-Primel, Finistére : : >. 100 
Map of Leckhampton Hill to show well-sinkings . : ; : : . 102 
Outline of tegmina of Etoblattina mazona, Illinois : é : : . 149 


Four figures of carina of Scalpellum accwmulatum, T. WH, Withers, sp.nov. . 152 


Left tergum of 8. comptum, T. H. Withers, sp. nov. . : : : . 158 
Four figures of carina of S. cyphum, T. H. Withers, sp. nov. é : loo 
Four figures of carina of S. aduncatum, T. H. Withers, sp. nov. . : 5 UE 
Left tergum of S. dissimile, T. H. Withers, sp. nov. . : : : - 158 
Geological map of Dolgelley Gold-belt . : : : é ; 3 = 203 
Geological map of St. David’s section of Dolgelley Gold-belt . : ‘ . 208 
Map of Tarntaler district, etc., Navis Valley, North Tirol . : : 4 245 
Sketch-map of Tarntal area . : : ; 3 : : : 6 . 246 
Diagram showing break in nival gradient. : 5 : : : Zou 
Section of the Drifts at Marros, near Amroth ; ‘ ; ‘ ‘ eS 


Two figures of broken and contorted laminz in stone of Sutton Church, Notts. 306-7 


Drift-bedding ripples in stone of Fledborough Church, Notts. : . - 307 


Dorsal shield (restored) of Glyptops ruetimeyeri (Lyd.) . : 2 : . 9312 
Plastron of G. ruetimeyeri (not restored) : : : : : : 6 lle! 
Map of the Augen Gneiss District of Ross-shire . : : 2 5 . 338 
Diagram of plate-crushing in Holectypoida . 4 : : ; é . 350 
Comparison of plates in four genera of Holectypoida_. : : . 361 
Section of cliff south of North Sea Landing, Flamborough  . é ; . 356 

394 


Figure of ‘ Dreikante’ in process of formation. - : : : Bae 


vill List of Illustrations in the Text. 


Four types of ridge-curves in ‘ Dreikante ’ 

Diagram of formation of curved-faced ‘ Dreikante ’ 

Five-faced wind-worn pebble 

Block of sandstone pierced by numerous borings from the Fayim, Egypt 
Section of Bagshot Beds, Shooters Hill, Kent 

Pygidium of Brontews Halli, sp. nov., Devonian, Gerolstein . 
B. thysanopeltis, Barr. (two figures), Upper Silurian, Bohemia 
B. speciosus, Corda, Devonian 

Section of Creechbarrow Limestone and underlying series 

Two figures of flint pebble, showing included organism . 
Section of shell of Ostrea cornucopie 

Two figures of Radiolites Mortoni 

Six figures of Pollicipes imbricatus, Withers, sp. noy. 

Three figures of P. unguis, J. de C. Sby. 


Section from Shooters Hill to Bostall Common 


THE 


GEOLOGICAL MAGAZINE 


OR 


Hlonthly Journal of Geology. 


WITH WHICH IS INCORPORATED 
THH GHOLOGIST. 
EDITED BY 
HENRY WOODWARD, LL.D., F.R.S., F.G.S., &c. 


ASSISTED BY 
Proressor J. W. GREGORY, D.Sc., F.R.S,, F.G.8. 
Dr. GEORGE J. HINDE, F.R.S., F.G.S, 
Srrk THOMAS H. HOLLAND, K.C.I.E., A.R.C.S., D.Sc., F.R.S., F.G.S. 
Proressor W. W. WATTS, Sc.D., M.Sc., F.R.S., V.P.G.S. 
Dr. ARTHUR SMITH WOODWARD, F.R.S., F.L.S., Sec.Grou.Soc., AND 
HORACE B. WOODWARD, F.R.S., F.G.S. 


JANUARY, 1910. 


‘Decade V.—Vol. VII.—No. I. Price 2s. net. 


5 GC @OaAN aeeN TES: 
I, OxnrernaL ARTICLES. Page III. Reviews. Page 
‘Olivine Nodules in Basalt, Calton Geology of Seaboard of Mid Argyll, 
Hill, Derbyshire. By H. H. Islands of Luing, Searba, etc., “ete. 
ArnoLD-BemrosE, J.P., See By B. N. Peacly H. Kynaston, 
F.G.S. (PlatesTandII.)... ... 1 and H. B. Muff /. 37 
Reeteni Now Chalk Polyzoa, By Geology of Sout Wales Coal- field. 
Re MER GS. a tell. & Part I. By Aubrey Strahan, F.R.S. 38 
EEDONE, (Plate IIT.) The Cretaceous Fauna of Poland ... 39 
AAolian Deposits, Coast of Etel, 
'  Morbihan. Part I. By Rev. R. IV. Reports AnD PROCEEDINGS. 
Asuincton Buttan, B.A. Lond., Geological Society of London— 
F.L.S. a IV and four Text- November Lip QUO Re ee re mcrae AO) 
oes:) Be gni ss Gales December lyre Set ot heer ee 
Pleochroi¢ Halos. eee P. Messer, V. Oprrvary. 
F.G.S. (Plate V.)  ... 15 | Hilary Bauerman, Assoc. R.S.M., 
Ore-bearing Pegmatites of Garrook Se eee eee in Suge Tet ae BORO 
Fell. By A. M. FINLAYSON, | a 
Mie eG Se: ch se ee ee 19 VI. Miscernanzovs. 
zs Appointment of Mr. O. T. Jones as 
: II. Notices or MEmorrs. Lecturer, Aberystwyth... ... 48 
Evidences ot Former Land-bridge Appointment of Mr. H. J. Seymour 
between Northern Europe and . as Professor of Geology in oe 48 
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price 20s. net. Cloth Cases for Staged may be had, price 


A COMPLETE REPRODUCTION OF THE SKELETON OF 
DINORNIS MAXIMUS 


(the gigantic ‘ Moa’ of New Zealand) as supplied to the Natural History Museum, 
Brussels, by 
ROBERT F. DAMON, Weymouth, England. 


Height 300cm. 


THE 


GEOLOGICAL MAGAZINE. 


NEW, SERIES.,, DEGADE.V....VOL..VIl. 


No. I.— JANUARY, 1910. 


ORIGINAL ARTICLES. 


a 


I.—On Oxivinr Noputes 1n tHE Basatr or Catron Hitt, 
DERBYSHIRE. 


By H. H. Arnotp-Bemrosz, J.P., Se.D., F.G.S. 
(PLATES I AND II.) 
InrRoDUCTION. 


FYVHE object of this paper is to place on record the occurrence of 

olivine nodules in a British basalt which, though closely allied in 
structure to some of the Tertiary basalts of the Continent, belongs 
undoubtedly to the Carboniferous age. Olivine nodules frequently 
occur in the Continental basalts and have been considered by some 
writers as inclusions of peridotites, but by others as segregations from 
the magma. 

I can find no description of olivine nodules from any British basalt 
in which the olivine is in a fresh condition. The nearest approach to 
such a nodule is that described by Mr. 8. Allport, from Ballybrood, 
in the county of Limerick.! The rock, he says, ‘‘ contains small 
patches of red and green serpentine scattered through it.”’ ‘‘ In one 
of the largest patches there are several grains of olivine, and an 
examination in polarized light shows that it was originally a nest of 
olivine which has been almost completely altered to serpentine.” 

Dr. Teall,” in referring to Mr. Allport’s description, remarks that 
‘¢ this is an extremely important observation, because it is the only one 
yet made of the occurrence of anything like an olivine nodule in any 
British basalt”. 

In 1894, in describing a basalt from Calton Hill, Derbyshire, 
I mentioned the presence of olivine in small groups or nests of 
erystals*; and in 1907 I stated that I had found olivine in small 
nests of bottle-green colours. The largest nest of olivine and augite 
then found by me measured only 2°7 X 2:2 mm. under the microscope. 

Trial holes have recently been made in Calton Hill, Derbyshire, 
which is a volcanic vent of Carboniferous age, and a level has been 


1 «Qn the Microscopic Structure and. Composition of British Carboniferous 
Dolerites’?: Q.J.G.S., 1874, vol. xxx, p. 552. 
2 British Petrography, 1888, p. 246. 
3 Q.J.G.8., 1894, vol. 1, p. 621. 
+ Q:J:G-8:, 1907, vol. lxiii, p. 252. 
DECADE V.—VOL. VII.—NO. I. 1 


2 Dr. H. H. Arnold=Bemrose—Olivine Nodules in Basalt. 


driven through the agglomerate on the northern slope of the hill into 
the basalt. It has, therefore, been possible for me not only to examine 
the relationship between the agglomerate and basalt, but also numerous 
blocks of the basalt, many of which contain olivine nodules. The 
largest nodule I have found is 2} inches in length, and from one trial 
hole I obtained forty-nine nodules in less than an hour. 

_In the level, which is about 50 feet in length, the agglomerate is at 
first in horizontal beds. Further into the hill the beds dip to the 
south. The dip increases until it becomes nearly vertical at the 
junction between the agglomerate and basalt. The agglomerate varies 
in coarseness and consists of basalt lapilli either in a limestone paste 
or in a volcanic detritus. The former kind is very similar to the 
agglomerate of Ember Lane, near Bonsall. The agglomerate of 
Calton Hill contains lumps of limestone, which are often more or less 
marmorized, pieces of basalt and inclusions of silica and calcite, which 
are several inches in length. ‘Two thin slices of these inclusions were 
examined. They consist of crystalline calcite and of quartz grains, in 
the form of a mosaic, and are probably a secondary aggregate of quartz 
and calcite. 


Tae Basatr or Catron Hin 

consists of olivine and big augite phenocrysts in a groundmass of small 
felspar laths, augite grains, and prisms, and magnetite or ilmenite. 
The felspars and augite prisms often show a well-marked flow- 
structure. The constituents of the rock are generally in a. fresh 
condition. The olivine, which is sometimes altered to serpentine 
along the cracks, occurs in phenocrysts and in groups of phenocrysts, 
and in irregularly shaped grains. ‘lhe augite appears as large pheno- 
crysts, often showing hour-glass structure, and sometimes containing 
portions of the groundmass, and in small prisms and grains. Both 
olivine and augite are found together in small nests or groups of crystals. 
The felspars sometimes occur in two generations and often exhibit 
a flow-structure. 


THe Nopvutes. 

The distribution of the nodules is general throughout the basalt of 
Calton Hill. In a hand-specimen they are easily distinguished and 
appear as a crystalline aggregate of bottle-green and yellow olivine 
with dark augite in the fine-grained and nearly black basalt. Some 
of the nodules are in a very fresh state; in others the cementing 
material between the grains has been dissolved away and the small 
grains may easily be separated by the finger. The nodules consist 
mainly of olivine, but contain a fair proportion of augite, and in some 
cases a small quantity of picotite. These minerals occur in irregularly 
shaped grains without any crystalline boundary, except in very few 
instances, especially near the outside of a nodule. The grains are not 
deformed crystals, but have hindered one another’s development as far 
as crystalline boundary is concerned. Fourteen thin slices from the 
nodules were examined. 

The olivine in the nodules is often traversed by cracks containing 
serpentine, and in some cases calcite and oxide of iron. Otherwise 
this mineral is in an unaltered condition. It sometimes contains 


Grou. Maa. 1910. Puate J. 


Fic. 3. X20 


H.A.B., Photomicro. Bemrose, Collo. 
Olivine Nodules in Basalt. 
Calton Hill, Derbyshire. 


Dr. H. H. Arnold-Bemrose—Olivine Nodules in Basalt. 3 


inclusions which give it a very rough appearance under the micro- 
scope. Some of the olivine grains are twinned many times. One twin 
in thin slice 1479 consists of twelve portions, another consists of five 
parts. It is almost impossible to distinguish the boundaries of the 
twins in ordinary light, but in polarized light the whole or part of 
a grain is divided into broad plates which differ ttle from each other 
in colour, the sides of which, corresponding to the trace of the 
twinning planes are often, but not always, parallel to one another. 
The angles of extinction of adjacent portions differ only by a few 
degrees and extinction in all cases is either parallel or nearly parallel 
to the trace of the twinning planes. 

The pyroxene in the nodules is monoclinic and can only be referred 
to augite. In the absence of crystallographic outlines the only method 
of distinguishing between the orthorhombic and monoclinic pyroxenes 
is to measure the angles of extinction with regard to the cleavages 
and to observe the optic figures in convergent light. In the thin 
slices examined there is no certain trace of enstatite or orthorhombic 
pyroxene. On the other hand, the whole of the evidence points to 
the presence of monoclinic pyroxene or augite. Two types of cases 
occur in which the crystalline grain is traversed by parallel cleavage 
lines. In the one extinction takes place parallel to the traces of 
cleavage and in convergent light shows an optic axis just outside the 
field of view. These are augite grains parallel to (100). In the 
other the angle of extinction varies from a few degrees up to an angle 
of 45° and denotes augite from the prism zone. Few cases are present 
of pyroxene showing an almost rectangular cleavage, but im all 
these there is an optic axis nearly in the centre of the field, which 
proves that the mineral is augite and not enstatite. 

Picotite is present in the nodules only to a slight extent. It is of 
a yellowish-brown colour in ordinary light and becomes extinct under 
crossed nicols. 

The presence of olivine and of augite in small groups from almost 
microscopic dimensions up to a length of more than two inches in the 
Calton Hill basalt is in favour of the nodules being segregations from 
the magma and not enclosures of older rock. 


EXPLANATION OF PLATES I AND II. 


[The figures were photographed by the author from the microscope, under polarized 
light with crossed nicols. ] 


Prate [. 


Fic. 1. Thin slice (1464), magnified twenty diameters, showing olivine grains in 
anodule. The olivine is traversed by cracks containing serpentine and minute 
pieces of black iron ore. 

Fic. 2. Thin slice (1464), magnified twenty diameters, showing olivine grains in 
a nodule. The grain of olivine near the centre of the figure is twinned ; one 
portion of the twin extinguishes parallel to the trace of the twinning plane and 
the other at an angle of 4° with it. 

Fic. 3. Thin slice (1479), magnified twenty diameters, showing part of a large 
grain of olivine in a nodule. The olivine is traversed by cracks and shows 
multiple twinning. The twinning planes are not always parallel, and the 
extinction angle of each portion of the twin is either parallel or nearly parallel to 
the trace of the twinning plane. 


4 R. M. Brydone—On Chalk Polyzoa. 


Puate II. 


Fic. 1. Thin slice (1459), magnified fifteen diameters. The two large dark grains 
with parallel cleavage lines are augite. That on the left extinguishes parallel to 
the cleavage and shows in convergent light an optic axis just outside the field of 
view, and is, therefore, parallel to (100). The lighter one at the left-hand 
bottom portion of the figure extinguishes at an angle of 5° with the cleavage 
cracks and shows only a slight trace of an axial figure. To the left and the right 
are several olivine grains. At the right-hand top corner is a small portion of the 
basalt in which the nodule occurs. 

Fic. 2. ‘Thin slice (1459), magnified twenty diameters, showmg the junction 
between a nodule and the basalt in which it occurs. In the nodule, in the upper 
part of the figure, olivine and augite are seen, and in the lower part the flow- 
structure of the felspar microlites in the basalt. 

Fic. 3. Thin slice (76), magnified fifteen diameters. Basalt containing phenocrysts 
of augite and olivine in a groundmass of felspar microlites of magnetite and glass. 
The big crystal of augite, to the left, contains inclusions from the groundmass 
zonally arranged. On the right is a small phenocryst of olivine. 


IJ.—Novrs oN NEW oR IMPERFECELY KNOWN CHALK Potyzoa. 
By R. M. Brypong, F.G.S. 
(PLATE III.) 
(Continued from Vol. VI, p. 400.) 
Mrmpranipora HuMILIATA, noy. Pl. III, Figs. 1-3. 


Zoarium always adherent. 

Zoecia generally elongated, but very variable in shape and dimen- 
sions; length of area ‘68 to -48 mm., breadth of area -386 to -2 mm. ; 
no front wall, side walls very low, with a further depression at the 
head of the zocecium, and furnished all round with slender buttresses, 
whieh are much more easily distinguished in the upper part of the 
zoecium, owing to their greater size and projection there, than in 
the lower part. 

Owcia semi-elliptical in outline, relatively very small, very frequently 
present, very brittle and especially so when associated with avicularia, 
so that zocecia with typical arrangement of perfect ocecium succeeded 
by avicularium are exceedingly rare. 

Avicularia accessory, small oval rings lying at the head of the 
zocecium and normally symmetrically above the ocecium when present, 
but sometimes beside it. 

The species is easily distinguished by the abnormal shallowness of 
the zocecia, which makes specimens look to the naked eye like much- 
worn remains of other species, and causes such inequalities in the 
underlying surface as the smaller tubercles of Zchinocorys, which 
would be out of sight at the bottom of zocecia of normal depth, to 
show up most prominently. 

Fairly common at Trimingham. 


MEMBRANIPORA ANTERIDES, nov. Pl. III, Figs. 4-6. 


Zoarium always adherent. 

Zoecia pyriform with subtriangular area and considerable extent of 
front wall below it; length of area -32--36mm., width of area 
‘2-24 mm.; side walls supported by buttresses; at the head of the 


Grou. Maa. 1910. Puate II. 


Fie. 1. X15 


Fie. 3. x15 
H.A.B., Photomicro. Bemrose, Collo. 


Olivine Nodules in Basalt. 
Calton Hill, Derbyshire. 


7 Tete 
N 7 i és 
~—s MAN 

Tet 


Grou. Mac. 1910. Pruate II. 


R. M. Brydone photo. 


Chalk Polyzoa (Bryozoa). 


R. M. Brydone—On Chalk Polyzoa. f 9) 


zocecium there is generally in the central line a buttress distinctly 
bigger than the others, with a considerable interval on either side of 
it. The zocecia are much deeper than those of IL. humiliata, though 
still on the shallow side, and their edges are wrinkled, but so faintly 
that it is only clearly discernible with the larger magnification. 

Oecia more globose than those of IW. humilvata. 

Avicularia very similar to those of IL. humiliata. 

The typical arrangement of the ocecium and avicularium is the same 
as in I, humiliata, but while they never lie side by side, in one instance 
two avicularia have been found to one zocecium, which arrangement 
is at present unknown in JZ. humiliata. 

_ Not uncommon at ‘Trimingham. 

The system of buttressed walls which this species shares with 
MM, humiliata marks them off clearly from all other Cretaceous 
Uembranipore, but the typical arrangement of avicularium above 
ocecium links them, probably only superficially, with IZ. Griffith: pod 
M. Trimminghamensis. 


Memepranrpora TrimmMincHAMENsIs, mihi. PI. III, Figs. 7 and 8. 


I take this opportunity of supplementing from photographs of the 
type-specimen the figure given with the original description. Further 
study has shown that the two upper pairs of granules are perforate 
and the ocecia are shaped like an inverted water-bottle, the expanded 
lip curving round and practically hiding the uppermost pair of 
granules, which are smaller than the succeeding pair. Length of 
area *36 mm., width -28 mm. 

In describing this species (the specific name of which should have 
been spelt Zriminghamensis) and I. Griffithi I omitted to discuss 
Cellepora trifaria, Hag.,' which shows a similar arrangement of 
ocecium and avicularium, relying perhaps overmuch on the facts that 
Marsson did not refind such a form at Rugen, and did not find the 
species recognizable in Hagenow’s collection. The figure appears to 
be taken from a worn specimen, which might equally well be 
M. Grifithi, M. Triminghamensis, or some other species. The de- 
scription only adds the feature of possessing large earshaped avicularia ; 
and these separate it as well from J/. Triminghamensis, which has 
no large avicularia, as from I. Grifithi, which has symmetrical large 
avicularia, while the ear is decidedly unsymmetrical. Cedlepora trifaria 
cannot. therefore be treated as a valid anticipation of either of the 
other species. - 

EXPLANATION OF PLATE III. 
Fic.1. Membranipora huniliata. x 20. 


,, 2. Ditto, another specimen showing perfect ocecium associated with avicularium. 
in typical arrangement. x 20. 


45 Bo LIDAR: Wee 0p 

5, 4. Membranipora anterides. x 20. 

ap Oo JO iinKOST | 5S Zh)s 

,, 6. Ditto, another specimen with the buttresses showing dark against w hite 

chalky >< 20% 

>, 1. Membranipora Lriminghamensis, type-specimen. x 20. 

», 8. Ditto, type-specimen, lighted to show bar across perfect avicularia. x 20. 
1 


Geinitz, Grundriss der Versteinerungshunde, p. 617, pl. xxiiiJ, fig. 40. 


6 Rev. R. Ashington Bullen—Bolian Deposits at Etel. 


IlI.—Norrs on tHe Aor1an Deposrrs oN THE Coasr ar Even, 
Morsraan. Parr I. 
By Rev. R. Asuineron Buuuen, B.A. Lond., F.L.S., F.G.S8., ete. 
(PLATE IV.) 


§ 1. Etel: Introduction. 

§ 2. Raised Beach recently exposed. 

§ 38. The Granulitic Rock. 

) 4. Traces of Post-Neolithic Submergence. r 

§ 45. General remarks on the direction of the Riviere d’Etel, near the sea. 

» 6. The present Terrace Beach of pea-sized gravel. 

§ 7. The four Terraces on the seaward side, and their flora. 

§ 8. The Aolian Transport of Sand, etc., to form the Dunes. 

\ 9. Marine species contributing materials for dune formation, especially Mollusca. 


§ 10. Analysis of the Dune Sand. 
¢ 11. Need of further work on Sand-dunes. 

§ 1. Etel is situated on the west of the Megalithic district of 
which Carnac is the centre. It stands about 2 kilometres from the 
sea on the Riviére d’Etel. This so-called river is really an arm of the 
sea, which drains the extensive estuarine basin to the north-east, 
which is, in its way, almost another Morbihan (Little Sea) similar to 
the well-known one farther east. ‘The tide rushes into the latter at 
a rate of from 7 to 11 knots per hour, at neap and spring tides 
respectively, and its ingress into and egress from the Riviere d’Etel 
cannot be much less. M. P. Le Strat, who has been much at sea in 
different parts of the world, considered that the incoming tide was 
rushing in at a rate of 7 or 8 knots an hour under the bridge of 
Lorrois, where the river narrows, when we passed it on October 11, 
1909. The channel of the Riviére d’Etel is thus kept permanently 
open, and ships of from 50 to 150 tons are engaged in the tunny 
fishery and smaller boats in the sardine trade. Messrs. Peneau have 
a sardine-curing establishment at La Magoire, just opposite, across 
the river (Diagram, Text-fig. 1, p. 7). 

An expert naval officer kindly furnishes the following information :— 

(1) The rate the tide enters the Riviére d’Etel is 4 knots on the 
flood and it leaves at 5 on the ebb at spring tides. The latter, under 
special circumstances, might be more, but the amount the sailing 
directions give is the usual rate. 

(2) The depth in the navigable channel is from 33 to 8 fathoms. 

(3) The depth on the bar is about 1 foot at lowest water. The 
rise of water above this is, springs 16 or 17 feet, neaps 12 or 18 feet. 

(4) The bar has been known to dry as much as 8 feet at low-water. 
The wind also causes it to shift. 

(5) A hurricane blows from 80 to 100 miles an hour. The pressure 
at the latter speed is 492 lb. per square foot. 

§ 2. Quite recently the road to the beach at the point marked (x ) 
in the map, has been widened, and the clear perpendicular section 
reveals a Raised Beach, the base of which is about 15 feet above 
high-water mark, which probably, at the recent spring tide early in 
October (7th) last, reached its maximum, as it was aided by strong 
gales. The section of the Raised Beach now exposed shows a thick- 
ness of 2ft. 3in. to 2ft. 6in. It consists of well-rounded pebbles 
of opaque-milky, transparent, or fibrous quartz, stained a deep red, 


Rev. R. Ashington Bullen—MHolian Deposits at Etel. 7 


together with what is probably Lydian Stone: but these rocks must 
form the subject of a second part of this paper. This raised beach 


aon N 
Wet 
PL 
Kem, 
2 SZ 
Gs y Etel : 
Sp Raised 
Beach 
c.de} § 
: OG Ay S: 
Le Chaudronmer YS/ -p 
Barre \ & ae 
ao fe Echelle metrique. 
aN) 
: | 500 
a 
- : “e, 1000 2000 6000 4000 5000 melres 


Fie. 1. Diagram of Etel, estuarine area, rivers omitted. [N.B. for Lottois read 
Lorrois. ] 


is overlain by from 33 to 4 feet of very dark brown, vegetable, peaty- 
looking mould, irregularly and sparsely scattered in the lower half 
of which are similar raised-beach pebbles (Text-fig. 2). Untor- 
tunately, the rest of the Raised Beach on the other side of the road 
has been quarried away, but the section that remains above the solid 
granulite contains a few scattered pebbles. No local granulitic pebbles 
occur in the Raised Beach, although some angular granulitic fragments 
do occur in the ‘overburden’ of mould. After careful examination 
no marine shells, fragmentary or otherwise, were to be seen in the 
Raised Beach. The absence of local stone in the Raised Beach itself 
is noteworthy. The raised beaches of this region must have been 


8 Rev. R. Ashington-Bullen—Holian Deposits at Etel. 


formerly very extensive, judging by the vast number of derived 
pebbles of the same materials to be found on the present beach at Etel 
and elsewhere, and on the exposed point near the barre on the left 
bank of the river. 


OS el hefowenviet Is 
ee 
oe a a a 
= 3 
fo) °o se) co) ro) 
ro) (o) ° @) 2) oO ° ° ° Oo 


jen made ie 
Kough : leading upto Town 
I” road along Jalaise and down to shore. 
nled with masonry 


Fic. 2. Raised beach quarried away on east side of road. 


1. Granulite: about 2 ft. 6in. in deepest exposure. 

2. Raised beach: resting directly on the solid rock, 2 ft. 3in. to 2 ft. 6 in. 

3. ‘Head’: with occasional subangular granulite in its upper part and scattered 
pebbles in its lower, 3 ft. 6 in. to 4 feet, mould dark-brown peaty colour. 


§ 38. The underlying rock of the place is ‘ granulite’ (using the 
term in its French sense). ‘‘ La granulite forme trois trainées 
principales, toutes dirigées a 104° et par suites paralléles entre elles. 
La premicre (trainée de Locronan), trés étendue sur les feuilles 
voisines, ne forme que le coin N.E. de la fenille; la seconde (trainée 
de Rosporden) s’étend de Trévoux a Inzinzac; la troisiéme (trainée de 
Port-Louis) s’étend des [les Glenan a Etel .. . la granulite de la 
diéme trainée est plus franche (de la structure feuilletée) plus massive 
et a plus gros grains, dans les falaises des Glenans, de Ploemeur, de 
Port-Louis et de Gavre; sphéne, mica noir trés épigenisé en mica 
blanc, mica blanc, oligoclase, orthose, microcline, quartz.”’! Grains of 
mica are plentiful in the present beach-sand and in the blown-sand of 
the dunes, thus showing that the blown-sand is derived from the 
present beach. i 

Between the fles Glenan, 60 kilometres to the west of Htel and 
the mainland, the trawl brings up large pebbles of granite and 
porphyry, which belong to the raised beaches of the region. But the 
rolled pebbles that are found in the gréves of Plouhinec (5 miles from 
Ktel westward) and behind the sand-dunes seem to have been derived 
from a different district from the pebbles of the Glenan area. 

_ According to the French survey the district between the Blavet and 
Htel Rivers bears traces of a vast and ancient estuary.” 

§ 4. Large masses of peat, some 14 to 2 feet across, and about 
3 inches thick, one rolled into a rounded peat ‘boulder’, occurred on 
the sea face of the coast, near the ‘ Chaudronnier’ or ‘ Pierre d’Htel’ 
(see Diagram 3), and these, derived from some submarine area, coupled 


1 Note explicative, Sheet 88, Carte Géologique détaillée de Bretagne. Note 
explicative, Sheet 89, Carte Géol. det. ‘‘ Cette granulite . . . continue de Port- 
Louis 4 la Rivicre d’Auray.’? Mr. F. H. Butler points out that the French 
‘granulite’ is equivalent to the fine-grained muscovite-biotite granite of English 
petrologists (vide Harker, Petrology for Students). 

* Tbid. 


Rev. R. Ashington Bullen—AHolian Deposits at Eel. 9 


with the ‘ Dolmen-sous-marin’ overgrown with seaweed, near Carnac- 
Plage and others elsewhere, point to a movement of subsidence, in or 
after Neolithic times, and posterior to the Raised eee epoch, similar 
to that of the British Isles.‘ (See Plate LV, Fig. 1.) 

§ 5. The course of the Riviére @Etel from Etel to the sea is 
almost due north to south, and is undoubtedly due to the underlying 
granulite, which crops out at the Lighthouse point with a slight orienta- 
tion to the south-east, and a dip to the east. We were exceptionally 
favoured with a violent gale on October 8, 1909, so that the action of 
the prevailing south-west wind could be well observed. The sea 
broke with unceasing fury on the granulite mass, one large rock of 
which standing close in- shore, the “Pierre d’Etel, well named the 
‘Chaudronnier’, on which a Deacon is built, was in a constant smother 
of water and at times invisible. There is a ladder up the beacon, but 
the chance of any swimmer reaching it would be very small. The 
lighthouse is built on the solid land farther in from the sea. 

On this side of the river (the right), for 12 kilometres, stretch dunes 
of blown-sand, used by the French Government for testing the heaviest 
artillery, occasionally with fatal results to indiscreet explorers.. Last 
year (1908) an ancient building, rather primitive, was unearthed 
about a kilometre south of La Magoire. The Curé.of Plouhinec 
considers that this is an old chapel of Ste. Brigitte, the church of 
a small settlement of poor fishermen, burnt down during some raid. 
It was surrounded by burials, but so far [ have been unable to learn 
any more about its age. The sand-dune which covered it being 
cleared away, much charred wood was found and some interments. 
There are no modern buildings near it; the sand has now entire 
possession of the place (Diagram, Text-fig. 3, p. 10). 

Judging by the size of some of the lichens, these dunes have 
not greatly increased inland for several years, any increase probably 
taking place along the sea-edge of the area. The absence of pebbles 
on this series of dunes is remarkable, and also the fineness of the sand. 

The natural effect of the south-west wind would be to bend the 
mouth of the river to the south-east, but the strong scour of the 
incoming and outgoing tide is such that the contour of the banks is 
not altered nor is there anything at the mouth in the nature of 
a ‘ fleet’, and the barre across the entrance can be sailed over at all 
suitable times of tide. 

§ 6. Passing now to the consideration of the east or left bank of 
the Riviére d’Hitel, near its mouth, along the edge fretted by the 
waves (which is a somewhat coarse quartz sand), we find that above 
the tide-mark landward, for a distance of some 200 yards in breadth, 
the beach material is a quartz gravel of well-worn oval or round 
pebbles, mostly varying from the size of a pea to a small French bean, 
out of which small gravel everything has been riddled, seemingly by 
the action of the prevalent south-west wind. 

There are occasional lines of large white gravel, resembling the 
stones of the Raised Beach ( x ) before described. (Text-fig. 1, p. 7.) 

‘ See Prestwich, Geology, vol. xi, p. 525; Q.J.G.S., 1892, vol. xlviti, p. 304. 


Also ‘* Les Megalithes submergés des Cotes de Vendée”, par Dr. Marcel Baudouin: 
L’ Homme Préhistori tque, 1& Mai, 1905, No. vy, pp. 130-48. 


10 Rev. R. Ashington Bullen—Aolian Deposits at Etel. 


The small pea-sized gravel underlying these lines of stones pre- 
dominates. It is noteworthy that the same sort of gravel occurs at 
Constantine Island, Cornwall, as a Raised Beach! underneath the 
blown-sand, and on which the prehistoric, probably Neolithic, oblong 
‘potter’s house’ (discovered by Mr. Harold Hellyar, of Harlyn) used 
to exist before it was ruthlessly destroyed in 1902. 


Li tet 


Seviére a 


Fic. 3. Diagram of the Riviére W’Etel below Etel and La Magoire. 

1, 2, 3, 4, successive terraces. yp, pond. Y,, granulite outcrops. t+ Tt, marine 
mollusca. <A, steep face of present beach. 

Sepia officinalis, Bittium reticulatum, M. edulis (Young), Cy. europea, Cardium 
edule, various Tapes, Donax vittatus: very abundant on lett bank from f to fF. 

The sea-front material, now acted on by the waves, consists of 
a coarse sea-sand which appears to be driven in from seaward. The 
small pea-gravel appears to be much older than this coarse sea-sand, 
and the question naturally arises whether the former is not rather to 
be correlated with the before-mentioned Raised Beach (xX ), close to the 
town of Htel, especially as it stands at nearly the same level above 


1 Prestwich, Q.J.G.S., vol. xlviil, p. 282. 


Rev. R. Ashington Bullen—AHolian Deposits at Etel. I] 


high-water mark. At any rate, one thing seems certain, viz., that 
the pea-sized gravel is not being added to by wind or wave at the 
present time, nor for a long time past. At the same time it is well to 
mention that the pebbles of the Raised Beach ( x) stand directly on 
the bare granulite and are not underlain by the pea-gravel, though 
this may only be because so much of the foreshore of the Raised Beach 
has been destroyed by erosion. 

§ 7. The pea-gravel and blown-sand rise in terraces, commencing 
above the coarse sand of the sea-front, in the various stages of con- 
solidation which are roughly indicated by the accompanying section 
(Diagram, Text-fig. 4). 


ae 
Ro 
“ 
i & 
8 Se) a as 
2 SS Ss 
§ g Sse oss 
Sw IS BSIRH LSE 
SS.8 3 5e8as —s 
SES 20 SSys se Aasae 
) Yss RSS Q 
cE aes Verses 
9 fee 
> 858 S 
§ eae Tor &ft 


x Zi a Fi 

‘on oreshore 
Fie. 4. Diagram of terraces at mouth of river, left bank. (For relative positions 
see Diagram, Text-fig. 3, p. 10.) 


The plant which bears the brunt of the storm nearest the sea-front 
on the first terrace about 7 or 8 feet above high-water mark, is 
a Crucifer, Cakile maritima, Scopoli. I counted thirty-seven clumps 
of this hardy plant. The next terrace, about 9 feet higher, is occupied 
by seaside cotton weed, Diotes maritima, Coss.; chamomile, Matricaria 
tnodora, var. maritima, L.; sea-spurge, Huphorbia paralias, L.; asmaller 
species of spurge, EK. peplis, L. They occurred in the order named as 
to precedence, though they were, of course, mixed together in the rear. 

Behind these there occurs a small depression, at a much lower level, 
containing brackish water, probably at sea-level, and about 150 yards 
from the sea-margin. The salt water would be able to filter in through 
the intervening sand and the depression would also act as a soak for 
fresh water from the dunes. The shells that occurred in the saline 
pond were Natica catena and Cardium tuberculatum principally. 

Behind the second terrace and up its slope seaside cotton weed was 
in great abundance, the marram grass, Ammophila arenaria, Link,’ 
only commencing to appear on this third terrace, at a height of 25 feet 
or so above high-water mark. With the marram grass were associated 
the above-named spurges, and also bedstraw, Galium arenarium, Loisel ; 
Ranunculus ficaria, L. (lesser celandine); thrift, Armeria maritima, 
Willdenow ; and a dwarf rose, from 1 to 4 inches high, osa 
pimpinellifolia, Loisel. 


1 Coste, Flore de la France, iii, p. 562. 


12) Rev. R. Ashington Bullen—Molian Deposits at Eel. 


Farther inland comes a fourth terrace, about 50 yards north, on 
which occur large patches of Rosa pimpinellifolia, and also equally 
vigorous sea-grape, Ephedra distachya, L., whose sweet, slightly 
acidulated berries in rank abundance coloured the dunes a brilliant 
coral-red. Also in smaller quantity occurred sea campion, Svlene 
maritima, Withering; a dwarf ribwort, Plantago maritima, L.; and, 
of course, marram grass. What strikes one is the fact that the marram 
grass only occurs where the sand grains become small and therefore 
plays a subordinate part in ‘dune formation’ on this coast. Indeed, 
the mosses and lichens seem of almost equal importance with the 
marram grass in covering and consolidating the finer sand. This 
remark also applies to the sand-dunes of Perranzabuloe and the Trevose 
peninsula. Along this terrace at the foot there is a well-defined 
beach of large quartz pebbles. i 

On the opposite side, the right bank, of the Riviére d’Etel, 
near the lighthouse, where the sand is fine-grained, marram grass 
comes well forward to the advance-guard of yellow-horned poppy, 
Glaucium flavum, Crantz (luteum, L.), not more than 30 yards from 
the sea-front ; the latter plant also occurs in abundance with sea-holly, 
Eryngium maritimum, L., on the second terrace of the left bank above 
described, where the plants are rather more sheltered (see Diagram 3). 

Many other plants also occur in the groups on the third and fourth 
terraces ; it is not, however, the purpose of this article to be botanically 
exhaustive, but only to trace the principal plant-agents in helping to 
consolidate the sand-dunes. Those who wish to do so, will find the 
subject more fully treated in a paper by M. Eugéne Simon.' 

§ 8. On the sand-dunes occur a number of marine shells, many 
of them of considerable size and weight, e.g. Massa reticulata and 
Purpura lapillus. They are found at heights of quite 30 feet above 
the highest tides. It is difficult to account for their occurrence. They 
are not used for human food; these dunes are singularly void of bird- 
life; the dunes are not cultivated by man, nor, so far as one can see, 
have the shells been accidentally dropped in the places where they are 
found by farmers wheeling them across the dunes with seaweed, and 
they occur in places where fishermen’s nets are not dried. Also they 
occur in places where there is no reason to carry them, for there are 
easier ways to the cultivated fields at the back of the sand-dunes. 
Nor, on the other hand, does wind seem to be the direct transporting 
agent. In the violent storm of October 8 last I placed single valves 
of such large shells as Cardium tuberculatum on their convex side; the 
south-west gale simply turned them over and propelled them no 
farther. Yet C. tuberculatum, either as whole shells or fragments, 
occurs plentifully at all levels up to the heights named above. 

Probably the wind acts, in a sense, indirectly in moving molluscan 
and other remains up the sand-slopes to the higher levels. The 
movement of the sand-grains inland is facilitated by the threshing 
action of stranded and moored seaweed, which, detaching the particles 
from the beach, causes them to be borne along in the direction of the 


1 « Notes sur les associations yégétales maritimes’’: Niort. Bull. Soc. Bot. des 
deux Sévres, 1902 (19038), xiv, pp. 242-50. 


Rev. R. Ashington Bullen—Holian Deposits at Etel. 18 


wind. Quite large bundles of seaweed were observed rolling along 
the surface of the sand, and probably here we have an explanation of 
the fertility of the dunes in their own peculiar flora, and also of the 
presence of even large sea-shells on them, which shells, entangled in 
the masses of dryish seaweed would be easily transported inland and 
rolled upward. This would be especially easy on the sand-dunes of 
the left bank, between the falaises (or sea cliffs, granulite capped with 
sand) and the pea-gravel beach, since the slope here down to the 
Riviére d’Etel is a very gentle one, for it does not rise in the bluff 
terraces that characterize the sea-front. 

§ 9. The materials that are triturated on the seashore or by the 
moving sand to yield the calcic portion of the sand-dunes are derived 
from marine Mammalia, Pisces, Mollusca, Echinodermata, Crustacea, 
and other flotsam and jetsam stranded on the shore. In October last 
two skulls of freshly dead Delphinus delphis,’ and a complete Phocena 
communis,’ whole fishes of the genus tunny, the ‘germon’ Z’hynnus 
alalonga, were there in August last, and their bones in abundance in 
October. Crabs of the genus Portunus were also in evidence, and of 
echinoderms Strongylocentrotus lividus and an embryonic heart-urchin 
were not uncommon. 

Mr. R. Holland has kindly examined the sea-sand submitted to him 
for foraminifera, and reports as follows: ‘‘ A prolonged search has 
resulted in the discovery of a few milioline only (probably JZ. semz- 
nulum, Linné). They are very poor specimens, and I have not come 
across a trace of any other genus of foraminifera. Besides the numerous 
mollusean shells I have noticed a few worm-tubes, one or two ostracod 
valves, a few echinoderm spines, and some very doubtful fragments 
of bryozoa.” s 

The marine molluscan fauna of Ktel resembles that of Weymouth 
in most respects. I give a list of species that I was able to collect. 
Those most abundant belonged to the Sepiide, Cardiide, Donacide, 
Mactride, Cypreeidee, Cerithide, Veneride, and Mytilide. Ostrea edulis, 
Pecten maximus, and Venus verrucosa were almost entirely represented 
by old valves, much bored by Cliona perforans, such material being 
easily broken by the pounding action of the waves. ‘These old shells 
are brought in from seaward. ‘This is an important point when we 
consider the sand-dunes as encroaching on the sea, since the sea is 
adding to the land from its own resources. 


CEPHALOPODA. G. cineraria, L. 
Sepia officinalis, L. Phasianella pullus (L.). 
S. rupellaria, D’ Orb. Scala communis, Lam. 
S. clathratula (Adams). 
GaASTEROPODA. Natica catena (Da C.). 
Patella vulgata, L. N. alderi, Forbes. 
Helcion pellucidum (L.). Littorina littorea (L.). 
Fissurella reticulata, Don. L. littoralis, L. 
Calliostoma zizyphinus, I. LI. rudis, Maton. 
C. exasperata, Penn. Rissoa costata, Adams. 
Gibbula wmbilicata, Mont. R. costulata, Alder. 
G. twmida, Mont. R. parva, Da C. 


1 Perhaps these should be excluded as they were probably killed by fishermen, but 
they show the possibility of such material floating ashore. 


Rev. Ki. Ashington Bullen—Aolian Deposits at Etel. 


Rissoa violacea, Desm. 

R. striata, Adams. 

R. membranacea, var. rabiosa, Mont. 
Rh. proxima, Alder. 

Rh. rufilabris, Mont. 

Alvania lactea, Mich. 

Barleeia rubra, Mont. 

Bittium reticulatwm (Da C.). 
Turritella communis, Risso. 

Chen pus pes-pelicani, 1. 

Cypren europea, Mont. 

Ocinebra erinacea (1..). 

Purpura lapillus (L.). 

Nassa reticulata (L.). 

NV. incrassata (Strom.). 

NV. pygmea, Lam. 

Buccinum undatun, L. 

Bela turricula, Mont. 

Mangilia (Hadropleura) septangularis, 


Pecten maximus, I. 

P. varius, L. 

P. pusio, L. 

P. opercularis, La. 

Lima hians, Gmel. 
Diplodonta rotundata, Mont. 
Tellina incarnata, L. 

T. balthica, L. 

T. tenuis, Da C. 

T. donacina, L. 

Gastrana fragilis (L.). 
Donax vittatus (Da C.). 
Spisula solida, var. elliptica, Brown. 
Mactra stultorum, L. 

Venus fasciata (Da C.). 

I”. verrucosa, L. 

Tl. gallina, Wh. 

V. chione, L. 

Trus irus, L. 


Mont. Tapes decussata, L. 
M. costata (Don.). T. aureus, Gmel. 
Thesbia nana (Lovén). T. pullastra, L. 

» Acte@on tornatilis, L. T. virgineus, I. 
Dentalium dentalis, L. Cardium tuberculatum, I. 
Acera bullata, Mull. C. norvegicum, Speng. 

C. edule, L. 
PELECYPoDA. Psammobia vespertina, Ch. 

P. ferroensis, Ch. 

Solen siliqua, Li. 

S. ensis, L. 

Pholas candida, UL. 

Pandora inequivalvis, L. 


Anomia ephippium, L. 
Arca lactea, Li. 
Mytilus edulis, L. 

M. adriatica, Lam. 
Ostrea edulis, Li. 


Brackish-water shells, brought down from the upper reaches, or 
living near Etel, where fresh water runs into the river, and mud 
accumulates. 

Lutraria oblonga, Ch. 
Scrobicularia piperata (Gmel.). 


Helicella barbara (L.), so common on our own sand-dunes in 
Cornwall, Portland, etc., was not observed at Etel. It occurred, with 
other xerophilous molluscs, at Auray, sunning itself on the hottest 
day of August last in the hottest places in bright sunshine on walls. 
On the other hand, Hele pisana, Mull, in countless myriads, provides 
its quota of material, organic and inorganic, to the general mass of 
the dunes. It is accompanied by Pomatias elegans, Mull., and Helicella 
itala, l., in considerable numbers. 

§ 10. The rough proportion of calcic material in the sand of the 
dunes is about one part in three by weight. I carefully dried the 

sand from the dunes, and then treated it “with hydrochloric acid; it 

was afterwards carefully washed eight times to remove the acid, and 
the residue after being thoroughly dried was again weighed, with 
the above result. Out of 875 gr. (2 oz.) Avoir., so treated, the 
residual quartz, mica, etc., weighed 582°625 gr., showing a loss by 
dissolution of 292°375 er. ‘of calcic material. Brttium reticulatum is 
so abundant as in places to colour the dune sand brown. ‘The colouring 
matter was dissolved with the shell material. 

§ 11. Much work remains to be done at our own sand-dunes, as 


Grou. Mac. 1910. Puate LV. 


Fic. 1. Submerged Dolmen near Carnac Plage. 
2. Granulite rocks at Cap de Garde. i 
3. View southwards close to the Raised Beach, Htel. 


F. P. Mennell—Pleochroic Halos. 15 


witness the hitherto unsuspected occurrence, November, 1908, of an 
old lake-bottom at Perranzabuloe,' 200 feet O.D. Though much of 
this chara-marl has been carted away by agriculturists as fertilizing 
agent, enough remains to yield a most curious limnic molluscan fauna, 
scarcely to be paralleled according to Mr. A. Santer Kennard, F.G.S., 
among the existing British freshwater fauna of the present day. 

T have to thank Mr. W. H. Griffin and my wife for botanical help ; 
and my friend Dr. Henry Woodward, F.R.S., for this opportunity of 
placing my notes for revision, if needed, before abler and more 
competent minds who have given thought to this fascinating subject. 


EXPLANATION OF PLATE IV. 


Fic. 1. Dolmen-sous-marin near Carnac Plage. 
», 2. Granulite rocks at Cap de Garde. The Chaudronnier, or Pierre d’Etel, 
surmounted by a beacon. The Lighthouse stands somewhat inland ( (see 
, next view). 
», 3 tel, viewsouthwards from close to the Raised Beach. The Lighthouse and 
storm signal station are to the right of the Chaudronnier. 


LV.—P.eocurotc Hatos. 
By F. P. Mennett, F.G.S. 
(PLATE Y.) 


(J\HE subject of ‘ pleochroic halos’ has become endowed with peculiar 

interest since Professor Joly suggested that they are due to the 
radio-activity of the inclusions round which they occur.” On looking 
into such petrographical literature as I possess, it appears that very 
few precise observations have been made regarding these halos, and it 
has occurred to me, therefore, that some of my own notes on the subject 
may be of general interest. 

Minerals causing or showing Halos.—The usual type of halo, as seen 
in rock sections, is a dark spot of roughly circular outline surrounding 
a small centrally situated enclosure in another mineral. The enclosing 
mineral may or may not itself be pleochroic, though it usually is so, or 
would appear so in thicker slices. The following is a list of minerals 
which have, to the writer’s knowledge, been found to show halos, 
though it must be stated that in some of them the phenomenon is very 
rare: biotite, augite, hornblende, muscovite, chlorite, tourmaline, 
cordierite, staurolite, and andalusite. As to the minerals producing 
the halos, identification is not always easy, owing to their minute size. 
The following have come under the writer’s notice: zircon, sphene, 
apatite, orthite (allanite), and epidote. It is needless to point out 
that all these latter minerals (except, perhaps, epidote) are known to 
be, comparatively speaking, strongly radio-active. As far as the rocks 
are concerned, halos are far more common in those of igneous origin 
than in the other classes, and are especially noticeable in the plutonic 
types, particularly the granites. It may be noted that even zircon, 
round which halos are most frequently met with, may occur enclosed 
in such a susceptible mineral as biotite without the slightest trace of 


1 Proc. Malac. Soc., vol. viii, pp. 247 and 374. 
2 Phil. Mag., 1907, p. 381. 


16 rar Mennell—Pleochroie Halos. 


any halo being seen. However, a halo round zircon is certainly the 
normal state of affairs, and the same may be said of orthite. It is 
curious to notice that large crystals of these minerals may fail to give 
rise to halos, though these last may be conspicuous round the smaller 
crystals in the same slice. Round apatite and epidote halos are only 
occasionally seen, and are usually faint, while round sphene they are 
extremely rare. 

Shape of Halos.—It is evident that, if three dimensions are considered, 
halos are usually spherical, and thus give circular sections, except in 
cases where the enclosed crystal is distinctly elongated and of sufficient 
size for the difference of length and breadth to be appreciable. In the 
case of large irregular grains or granular aggregates the halo may be 
quite irregular in shape, but extends to a uniform distance from each 
part of the margin of the substance which it surrounds. 

Size. — A feature revealed by measurement is the remarkable 
uniformity in size of the halos. The distance to which they extend 
from the edge of the enclosed crystal appears practically uniform in 
nearly all cases. Of course there are numerous instances where halos 
apparently smaller than usual are observed, owing to the dark sphere 
not haying been cut centrally, but in these no nucleus can be seen. 
There do, however, appear to be some small halos which cannot be 
thus accounted for. On the other hand the alteration of minerals like 
orthite tends to produce stains which spread principally along cracks 
or cleavage planes, and must be carefully distinguished from real halos. 

The following are some approximate measurements, made by means 
of an eyepiece micrometer, of the breadths of fairly well-marked halos. 
seen round various distinctly visible minerals in a variety of rocks :— 


Rounp Zircon. 
mm, 


In biotite of granite, Haytor, Dartmoor . : .  *03-"04 
In biotite of granite, Rubislaw, Aberdeen : , “08 
In biotite of granite, Cowra, New South Wales . : 035 
In biotite of granite, Gadara, New South Wales : "02 
In biotite of granite, Cape Town : : F : 035 
In biotite of granite, Matopos, Rhodesia. c . 703-"04 
In biotite of granulite, Rhodes’ Drift, Rhodesia. : “04 
In hornblende of granite, Weinheim, Baden! . : “08 
In hornblende of granite, Bulawayo, Rhodesia? . P 08 
In hornblende of diorite, Jahonda, Rhodesia ‘ ‘ 035 
In augite of granulite, Amazon Mine, Rhodesia ' 3 03 
In chlorite of granite, Mountsorrel, Leicester . : 08 
In chlorite of granite, Matopos, Rhodesia . : 2 03 
In chlorite of granite, Cowra, New South Wales : “04 
In tourmaline of granophyre, Cornwall . 3 - 108-7035 
In tourmaline of granite, Cape Town. - : : 03 
In cordierite of granulite, Bodenmais, Bavaria . . "045 
In cordierite of granite, Cape Town . 2 . : “035 
In ‘pinite’ of granite, Cape Town. : 4 : 035 
Round APATITE. 
In biotite of granite, Cape Town : ¢ é - 03 
In biotite of diorite, Hillside, Rhodesia! . : ; “03 
In biotite of granulite, Amazon Mine, Rhodesia - 02 
In biotite of granulite, Rhodes’ Drift, Rhodesia : 03 


1 Nature of enclosed mineral somewhat doubtful. 


F. P. Mennell—Pleochroie Halos. 117/ 


Rounp SPHENE. mm. 
In biotite of granulite, Amazon Mine, Rhodesia : 02 
In hornblende of granite, Umguza River, Rhodesia . 03 
In augite of syenite, Hillside, Rhodesia! . 5 é 03 

RounpD OrrHITE (ALLANITE). 

In biotite of granite, Matopos, Rhodesia. : . *03-"04 
In biotite of eranite, Zimbabwe, Rhodesia a‘ "035 
In hornblende of granite, near Blanket Mine, Rhodesia 03 
In hornblende of © tonalite’, Adamello, Tyrol los ‘ 035 
In hornblende of diorite, J ahonda, Rhodesia ; : 04 
‘ Rounp Eprpore. 
In chlorite of granite, Matopos, Rhodesia : : 08 
In biotite of granite, Gadara, New South Wales ? 025 


The above measurements are necessarily somewhat rough, as it is 
difficult to keep an eye on the halo and the micrometer scale at the 
same time. However, the general result is to emphasize the uniformity 
of size and the fact that there does not seem to be any definite 
relation between such variations as are noticed and the minerals 
concerned. . 

Halos and Radio-activity.—Professor Joly has pointed out that the 
penetration of the a rays emitted by radium compounds is about 
‘04mm. in the case of aluminium, and having regard to the slightly 
ereater density of the minerals examined, the results are in close 
agreement with the theory that the halos are due to the alteration of 
the surrounding minerals by those rays. Some of the smaller halos 
were indistinct, and it seems possible that im several cases where 
rather low values were obtained, the radio-active substance was 
present merely as an inclusion in the interior of the mineral to which 
the halo appeared due. This is the more probable as such minerals as 
apatite and sphene cannot be radio-active in virtue of their normal 
constituents, or even their usual impurities.* Epidote, too, may 
owe its occasional activity to minute inclusions of orthite. As bearing 
on this point, may be noted a granite from the Zimbabwe Ruins in 
Rhodesia, which contains apparently primary epidote enclosed in 
biotite. The epidote in turn encloses irregular patches of orthite, and 
wherever the latter approaches within ‘035 mm. of the edge of the 
epidote, the biotite within that limit shows the usual darkening. 
It is noteworthy that zircon may always be expected to contain 
traces of thorium, and orthite invariably contains that element in 
appreciable amounts, and probably uranium as well in some cases. 
From a petrological point of view it seems as if thorium should be 
a far more potent cause of radio-activity in the earth’s crust than 
uranium and radium. We know of no widely distributed uranium- 
bearing rock-former, while zircon is found everywhere, and orthite 
is far from rare in many regions. Over 15 per cent. of my slides 
of granites contain it. Monazite, always rich in thorium, is also 


Nature of enclosed mineral somewhat doubtful. 
Radio-actiwity and Geology, p. 68. 
See, however, Strutt, Proc. Roy. Soc. A., 1908, p. 275. 
e See, for instance, Geo. Mae., 1903, Dec. IV, Yol. X, p. 347, and Geology of 
South Rhodesia, pp. 29-82. 


DECADE V.—VOL. VII.—NO. I. 2 


1 
2 
3 


18 F. P. Mennell—Pleochroic Halos. 


found in many rocks. It is as yet scarcely possible to judge how 
the recently discovered radio-activity of potassium affects the question, 
though the abundance of that element renders the fact of obvious 
importance. 

Various Features. —When the halos are fairly intense, they usually 
have quite well-defined boundaries, much more so than one is inclined 
to think before making a series of observations on the point. Where 
they are clearly perceptible in the direction of minimum absorption 
they show no increase of diameter when placed in the position of 
maximum absorption. Sometimes, however, a halo appears in the 
latter position, whereas none was perceptible in the direction at right 
angles to it. This is especially the case with such faint halos as those 
sometimes seen round epidote or sphene, or those in cordierite. The 
more intense halos are usually uniform in tint from inside to outside, 
or slightly lighter towards the outer edge. Irregularities in dis- 
tribution are, however, fairly frequent, and the halos are sometimes 
dark and light in uneven patches. In certain cases, too—always, 
apparently, round rather large inclusions—the halos may have a rim 
darker than the interior. ‘Thus, in the granite to the north of » 
Kahlele’s Kraal, in the Matopo Hills, Rhodesia, there are well- 
marked halos round good-sized orthite crystals enclosed in biotite. 
These halos are usually very sharply defined on the outside, and 
have the margins distinctly darker than the parts nearer the orthite. 
A similar feature may be noticed round some of the zircons in a 
biotite granulite from the neighbourhood of Rhodes’ Drift on the 
Limpopo River, Rhodesia. It is also well seen round the larger 
zircons in the well-known cordierite granulite of the Bodenmais, 
Bavaria. 

The halos round the minute zircons in the tourmaline of the 
Cornish granophyre (quartz-porphyry) in the list given above are 
interesting as extremely good examples of a phenomenon distinctly 
rare in tourmaline, though noticed long ago by Michel Lévy.’ 
That this mineral does not readily lend itself to the formation of 
pleochroic halos is obvious from the evidence of such rocks as the 
Cape Town granite. My slides of specimens from near the contact 
show several instances of small zircons at the junction of biotite 
flakes and tourmaline crystals, and whereas the biotite shows a semi- 
circle of intense pleochroism, the halos are incomplete, owing to the 
tourmaline being entirely unaffected. The same fact was noted at 
several junctions of biotite and cordierite, though in one case a good 
example of a composite halo, half in biotite and half in cordierite, 
was observed. Several fairly distinct halos were also seen round 
zircons, entirely enclosed in tourmaline, and we may perhaps infer 
that in these particular cases the enclosures were more strongly 
radio-active than usual. It is noticeable that where the cordierite 
of this rock has been altered into the so-called ‘ pinite’ pseudo- 
morphs, the halos are much more intense than in the fresh cordierite 
itself. Halos in hornblende are rather rare, though this is perhaps 
due partly to the much greater scarcity of inclusions than in biotite, 


' See Minéraux des Roches, p. 288. 


Aten 
sey 


Grou, Mac, 1910. PuLatTE V. 


ORS S EF LY MPT 
Wl ff / { if 


/} 


Pleochroic Halos around inclusions in various minerals. 


A. M. Finlayson—Ore-bearing Pegmatites of Carrock Fell, 19 


which seems always to have crystallized by preference on a nucleus of 
previously formed accessory minerals. In contrast to tourmaline and 
hornblende, it is remarkable to find halos well shown in such minerals 
as augite and muscovite, which are not normally pleochroic. It is 
also an interesting point that halos never seem to occur in minerals 
capable of causing them, a fact which appears entirely in accord with 
the radio-active theory of their origin. Thus there are none round 
the inclusions of zircon in the large orthite crystals of the Jibuyi 
River granite in North-Western Rhodesia, nor does the epidote of 
the same rock show any where it encloses orthite crystals, a feature 
which may also be noticed in numerous other Rhodesian granites, 
e.g. those of the Matopos, Kalomo, and the Zimbabwe Ruins. 

I must mention, in conclusion, my obligations to Mr. G. W. Card, 
of Sydney, who sent me the New South Wales rocks mentioned above, 
and to Mr. A. E. V. Zealley, who kindly brought to my notice the 
Cornish granophyre, also referred to. 


EXPLANATION OF PLATE JY. 


Ordinary type of circular halo round zircon in biotite, breadth about -035 mm. 
In granite of Matopo Hills, Rhodesia. 
2. Halo round irregular zircon inclusion in cordierite, rim of halo darker than 
interior. In granulite of Bodenmais, Bavaria. 
3. Halos round group of zircon crystals in biotite. In granite of Sea Point, 
Capetown. 
4, Halo round zircon in hornblende, breadth about 035mm. In quartz diorite of 
Jahonda, Rhodesia. ; 
. Halos round zircon in tourmaline. In Cornish granophyre, exact locality 
unknown ; slide lent by A. E. V. Zealley, A.R.C.S. 
. Halo partly in biotite and partly in cordierite, round zircon. In granite (near 
contact) of Sea Point, Cape Town. 
- Halo, with dark rim, round zircon in biotite. In biotite granulite, near 
Rhodes’ Drift, Limpopo River, Rhodesia. 
8. Semicircular halo in biotite, not extending into adjacent tourmaline. In granite, 
Sea Point, Cape Town. 
9. Halo, unevenly tinted, round apatite in biotite. In granulite, near Rhodes’ 
Drift, Rhodesia. salt 
10. Halo, with dark rim, round orthite (allanite) in biotite. In granite, north of 
Kahlele’s Kraal, Matopo Hills, Rhodesia. 
11. Halo in biotite, near inclusion of orthite in epidote. In granite, near 
Zimbabwe Ruins, Rhodesia. 
12. Halo, about -04 mm. in breadth, round orthite in hornblende. In quartz diorite 
of Jahonda, Rhodesia. 


(The magnification is about 100 diameters.) 


Fic. 
ike 


(ory 


bo | 


V.—Tue Ore-seartnc Prematires oF Carrock FELL, AND THE 
Genetic SIGNIFICANCE OF TUNGSTEN-ORES. 


By A.M. Fintayson, M.Sc., Assoc. Otago School of Mines, F.G.S., Assoc.Inst:M.M. 


Introduction—The wolfram veins in the Grainsgill greisen, near 
Carrock Fell, are an example of ore-bearing pegmatites, a vein-type 
uncommon in the British Isles, and one, moreover, the study of which 
is of much interest in its relation to ore-genesis. The veins have long 
been known, and intermittently exploited for tungsten-ore, but their 
economic prospects are not bright. Of previous workers, Mr. Alfred 


20 A.W. Finlayson—Ore-bearing Pegmatites of Carrock Fell. 


Harker has described the greisen which carries the veins,'! while the 
various mineral occurrences have been recorded by Mr. J. G. Goodchild ? 
and others. ; ; 

The Country Rock.—The veins occur in Brandy Gill, a small stream 
running into the Caldew from the western slopes of Carrock Fell. 
The country rock is a detached intrusion of greisen, related to the 
Skiddaw granite, and of post-Silurian age. Mr. Harker has pointed 
out that it is an acid modification of this granite, containing 77:26 
per cent. of silica, as against 75-223 per cent. in the normal biotite 
granite of Skiddaw.* In the ore-bearing portion, felspar becomes very 
subordinate or disappears altogether, white mica replaces biotite, and 
quartz phenocrysts compose the bulk of the rock. ‘Tourmaline occurs 
occasionally, but topaz and cassiterite are absent. In classing this 
rock as a greisen, Mr. Harker has shown that its features are due, not 
in this case to the action of pneumatolytic processes on a normal 
granite, but to intense mechanical pressure on the magma, resulting 
from the post-Silurian crust-movements, at the time of its intrusion.* 

The Grainsgill greisen has many features in common with the 
berestte of the Urals, which contains the gold - quartz veins of 
Berezovsk,® and with the alaskite of Mr. J. K. Spurr.® The latter 
rock, an acid modification of normal granitic or syenitic intrusions, 
occurs as dykes at Goldfield [Nevada], in the Yukon gold-belt of 
Alaska, and elsewhere. These various types are probably closely 
allied in nature and origin. 

The Veins——The wolfram veins in the greisen consist of some 
half-dozen chief members running north and south across Brandy 
Gill, and outcropping on the steep slopes on either side of the valley. 
They vary in width from a few inches to 3 or more feet, and 
consist essentially of coarse quartz, with flakes of pale mica and 
erystals of pale or bluish-green apatite. The vein-walls, though 
fairly well-defined, are not marked by clay selvages or slickensides, 
the veins being, in the phraseology of the American miner, ‘‘ frozen 
to the country.”” Another notable feature is the marked absence of 
pneumatolytic effects, such as the development of schorl-rock, topaz, 
or fluorspar in the vein-zones. 

The most easterly vein, which is also the largest, carries wolframite, 
with a subordinate quantity of associated scheelite, distributed in 
irregular bunches through the vein. ‘The quartz is conspicuously 
banded and comby, and small vughs are common. Some arsenopyrite 
is generally present, scattered through the veins in small crystals. 
Molybdenite also occurs, in its usual habit, but this mineral appears 
to be chiefly developed in a single vein towards the west, which is 

? Quart. Journ. Geol. Soc., 1895, vol. li, pp. 139 et seqq. 


ny 


2 ¢ Contributions towards a list of the minerals in Cumberland and Westmorland ”’: 
Trans. Cumb. and West. Assoc., 1881-2, vil, p. 101; 1882-8, vim, p. 189; 1883-4, 
They |Dn has 

3 Harker, loc. cit. sup. 

4 Id. ib., p. 1438. 

5 Von Arzruni, Zeits. deutsch. geol. Gesell., 1885, xxxvii, p. 878, and Posepny, 
Guide du VII Congrés Géol. Internat., 1897, v, p. 42. 

6 «Geology of the Yukon Gold Belt, Alaska’’; 18th Ann. Rep. U.S. Geol. 
Sury., 1896-7, pt. iii, p. 230. 


A, M. Finlayson—Ore-bearing Pegmatites of Carrock Fell, 21 


practically free from tungsten-ores. The small size of the veins and 
the sparing quantity and irregular distribution of the ores give no 
promise of ore-bodies of any consequence. As secondary products, 
there appear small quantities of the yellow tungstite (tungstic ochre) 
and molybdite (molybdic ochre). Native bismuth and bismuthinite 
are also recorded from this district, as well as the mineral griinlingite, 
a variety of tetradymite having the formula Bi, 8, Te.? 

The Vein-minerals and their Relations.—The quartz of the veins is 
glassy and crystalline, in coarse granules, and containing scattered 
patches of white mica. The apatite occurs in long striated prisms, 
terminated by the base or pyramids, and its colour varies from pale 
yellow or lemon-yellow to green. An analysis of the mineral gave 
the following result, showing it to be a fluor-apatite :— 


CaO = 54:11 Al, O3 = 0:87 
P20; = 40°56 Fes O3 = 1°05 
F = 2-98 MeO =0-24 
C = 0-66 


Total 100-47 

The vein-mica is commonly gilbertite, of a yellow or greenish tinge, 
frequently associated in flakes with the apatite. In Cornwall, where 
it was first described, this species often occurs as an alteration-product 
of orthoclase,* and in some districts it is pseudomorphous after both 
scheelite and apatite. Here, however, it appears to be of primary 
origin. An analysis of the mineral revealed the presence of 0:92 
per cent. of fluorine. This is of interest, in view of the widespread 
occurrence of fluorine in potash-micas, which has lately been emphasized 
by Mr. J. E. Spurr.* Thus the gilbertite from Ehrenfriedersdorf 
contains up to 1:04 per cent. of fluorine.t The very small quantity 
of fluorine or other ‘mineralizers’ in the Cumberland veins is in 
harmony with the absence of pneumatolytic products. 

The wolframite occurs in coarse bunches embedded in quartz. The 
prism-faces are longitudinally striated, and fairly complete crystals are 
not uncommon, the usual form being a combination of prisms and 
ortho-pinacoid, terminated by ortho-domes and pyramids. The com- 
position of the mineral, as determined by analysis, is as follows :— 


W O3 = 76:24 
FeO = 16°39 
MnO = 6:05 
CaO = 1:05 
Mie @ = —Orilil 


Total 99-84 


The scheelite is white to brownish.yellow in colour, and occurs, 
when crystallized, in tetragonal bi-pyramids. Under the microscope 
it is colourless, and when suitably cut shows its prismatic cleavages, 
p (111) and e (101), intersecting. The individual crystals, as dis- 
tinguished under crossed nicols, are coarse and closely interlocked. 


? Muthmann & Schroeder, Zits. Kryst. uv. Min., 1898, xxix, p. 144. 

> F. H. Butler, Min. Mag., vii, p. 79. 

= ** Geology and Mining Industry of Tonopah’’: Prof. Paper No. 42, U.S. Geol. 
Sury., 1905, pp. 231-3. 

* Frenzel, Jahrb. Min., 1873, p. 794. 


De A Oe: Finlayson—Ore-bearing Pegmatites of Carrock Fell. 


The mineral has been analysed by Traube, with the following 
result } :— 


\WOp = 73-Or 
CaO = 19°27 
Total 99°59 


The presence of molybdenum is worthy of note, this constituent 
having been shown by Traube to be almost universally present in 
scheelite. 

The relations of the minerals may be more clearly studied under the 
microscope. The opaque wolframite encloses quartz in thin strings 
along its cleavage-planes, as well as in granular aggregates. Separated 
grains of quartz are often seen to extinguish simultaneously, and at 
other times the two minerals simulate a graphic intergrowth. Again, 
quartz may occur as a thin selvage to the wolfram. The intimate 
association of these two constituents clearly shows close relation in 
order of deposition. While frequently there has been practically 
simultaneous deposition, on the whole the wolframite appears to have 
preceded the quartz. Crystals of arsenopyrite are almost invariably 
deposited on wolfram or formed in microscopic cavities of the ore. 
This sulphide is probably very largely of metasomatic origin. 

The scheelite, in contrast to the wolframite, is remarkably free both 
from arsenopyrite and from quartz. This would be expected from 
the fact that the arsenopyrite is a metasomatic product after wol- 
framite, and the wolframite and quartz were deposited about the same 
time, while the scheelite is clearly of later date. This mineral 
frequently fills cracks in the wolframite, and while the border-line 
between the two minerals is generally sharp, the scheelite is invariably 
deposited or grown on the older mineral. Occasionally the line of 
junction is irregular, and shows a gradual progression of the scheelite 
by replacement of the wolframite. The observed relations leave little 
doubt that the scheelite is metasomatic, although the processes are not 
in every case obvious under the microscope. The order of deposition 
of the minerals was apparently (1) wolframite and quartz, (2) arseno- 
pyrite and scheelite. 

It is to be noted that there are two lime-bearing minerals in these 
veins, namely, scheelite and apatite. The latter was perhaps the 
earliest of all in order of deposition, and it is not clear to what extent, 
if at all, the scheelite has derived its base from this constituent. In 
any case, this occurrence of lime is of interest, since it has been 
pointed out that in the magmatic differentiation of the greisen from 
the biotite granite of Skiddaw there has been a reduction of the 
alkalis and alkaline earths by 50 per cent. The lime in these two 
vein-minerals may then be taken to represent a portion of the surplus 
bases rejected by the greisen during its differentiation and crystal- 
lization, the lime being brought up at a later stage in the last phase 
of the magmatic processes, i.e. in the formation of the pegmatite-veins. 

Tungsten-ores and Metasomatism.—The formation of tungsten-ores 


1 Jahrb. Min., Beil. Bd., 1890, vii, p. 232. 
* Harker, loc. cit. sup., p. 142. 


A. M. Finlayson—Ore-bearing Pegmatites of Carrock Fell, 23 


is very frequently due to metasomatic replacement, and this may take 

lace in one of two directions. There may be a replacement of the 
acid radicle by tungstic acid; or there may be a replacement of the 
base by lime, or by iron and manganese oxides. The former process 
has taken place, for example, in the scheelite deposits of Trumbull, 
Connecticut,’ and in the scheelite-veins of Otago, New Zealand.? In 
both these cases, tungstic acid has combined by replacement with 
lime-bearing minerals in the vein-zone. Another important example 
is the wolfram-ore of the Black Hills, South Dakota. The second 
process is observed where scheelite is metasomatic after wolframite, as 
in the present instance; and likewise where the reverse change has 
occurred. ‘Thus, in the deposits at Trumbull, Connecticut, wolframite 
occurs pseudomorphous after scheelite. The latter change, i.e. from 
scheelite to wolframite, appears to be much the commoner. 

Fissure -veins at Grainsgill. —There occur, associated with the 
Grainsgill pegmatites, typical lead-quartz veins in fissures. An 
example is to be seen withina few yards of the most westerly 
pegmatite-vein, and contained also in the ereisen. It is bounded by 
sharply defined walls with clay selvages. The vein-filling is of 
brecciated, or banded and cavernous quartz, and the ore consists of 
small bunches of well-crystallized galena, with a little chalcopyrite. 
This vein has clearly been deposited in a fissure formed in the rock 
long subsequent to its consolidation, the fissure being, like all those 
which carry the lead-zine and copper veins of the Lake District, of 
post-Carboniferous age. We have here, then, two distinct vein- 
types, which show a striking difference, both in origin and in age. 

In this connexion, it is worthy of note that the lead-veins of the 
Lake District have yielded two minerals allied to those in the 
pegmatites, namely, wulfenite from Caldbeck Fell* and stolzite from 
Force Crag.° There has apparently been a reaction, at considerable 
depth, between the older tungsten and molybdenum ores and 
the younger lead-ores, which points to a broad genetic connexion 
between them. 

Genetic Relations of the Grainsgill Pegmatites—The modern views 
on the nature and origin of pegmatites have been recently summarized 
by J. B. Hastings,® who concludes that their essential feature is their 
dependence on aqueo-igneous intrusion, as applied to the influence of 
water in conjunction with heat in causing the liquidity of granitic 
magmas. In different cases it may be difficult to determine to what 
extent igneous intrusion on the one hand, and magmatic waters on the 
other, have been predominant, and it is impossible to postulate 
exclusively either aqueous or igneous agency, since there has clearly 
been a combination of both factors. G. H. Williams, in discussing 
the origin of the Maryland pegmatites,’ concludes that they are of 

1 W. H. Hobbs, 22nd Ann. Rep. U.S. Geol. Surv., 1900-1, pt. ii, p. 18. 

ae M. Finlayson, ‘‘ The Scheelite of Otago’’: Trans. N.Z. Inst., 1907, xl, 

. (. 
r 3 J. D. Irving, Trans. Amer. Inst. Min! Eng., 1902, xxxi, p. 683. 
4 J. G. Goodchild, Grou. Mac., N.S., 1875, Dec. V, Vol. IT, p. 565. 
° Greg & Lettsom, Mineralogy of Great Britain, London, 1858, p. 411. 


6 Bull. No. 21, Amer. Inst. Min. Eng., May, 1908, p. 319. 
7 15th Ann. Rep. U.S. Geol. Surv., 1893-4, p. 678. 


24 A.M. Finlayson—Ore-bearing Pegmatites of Carrock Feil. 


two types—segregation pegmatites and intrusive pegmatites. The 
view that pegmatites grade into normal quartz-veins has been main- 
tained in different districts by various writers, as, for instance, 
Crosby & Fuller,’ J. F. Kemp,’ A. H. Brooks,*® Joseph Barrell,‘ and 
A.C. Spencer.? R. Beck concludes that pegmatites are products of 
crystallization from superheated waters, which remained, after the 
separation of the chief constituents of the magma, as a concentrated 
solution containing the rarer metallic elements. He is thus in 
agreement with Brogger, Arrhenius, Vogt, and Grubenmann, all 
of whom support the intimate relation between pegmatites and ore- 
veins. Hastings expresses similar views with respect to the pegmatites 
of the Eastern United States,’ which he regards as true dykes, 
except where excess of water and of .mineralizers have produced, 
first, pneumatolytic tin- and apatite-veins, and finally veins con- 
taining gold, silver, or galena. 

The most pronounced advocate of the connexion between pegmatites 
and normal quartz-veins, however, is J. E. Spurr, who has advanced 
a theory of progressive derivation of gold-quartz veins from granitic 
magmas by siliceous magmatic differentiation.’ While this hypothesis 
may be locally applicable, there are, in many districts, difficulties in 
the way of its acceptance, owing to the absence of transitions from one 
vein-type to another. To take a single instance known to the writer, 
the gold-quartz veins of the west coast of New Zealand,° while related 
to the tectonic movements and granitic intrusions of the Alpine region, 
show no relation whatever with the abundant pegmatites and barren 
quartz-veins of the granites themselves. Again, in the Grainsgill 
district under consideration we have, on the one hand, ore-bearing 
pegmatites representing the super-acid phase of segregation and 
differentiation of the magma; and, on the other hand, lead-quartz 
veins in fissures, showing no (structural) similarity to the pegmatites. 
They have clearly been deposited from circulating waters at a later 
date. The occurrence in the lead-veins, however, of the minerals 
stolzite and wulfenite, serves to link the two types together to 
a certain extent, and to indicate that the ores have probably been 
derived from a common source. 

Geological Occurrence of Tungsten-ores.—The range of occurrence of 
tungsten-ores is very remarkable, and gives important evidence on 
the question of relations between the different vein-types. The facts 
of occurrence, with examples, are given below :— 

1. Pyrogenetic Minerals.—Tungsten-ores occur as original pyrogenetic 
compounds in granitic and allied rocks, chiefly as small percentages of 
tungstic oxide, often with tin oxide and molybdic oxide, in tantalates 


' Technology Quarterly, 1896, ix, p. 326. 

2 Bull. Geol. Soc. Amer., 1898, x, p. 361. 

3 20th Ann. Rep. U.S. Geol. Surv., 1898-9, pt. vii, p. 425. 

4 22nd Ann. Rep. U.S. Geol. Surv., 1900-1, p. 511. 

> Prof. Paper No. 25, U.S. Geol. Surv., 1904, p. 41. 

6 Rep. Brit. Ass., Trans. of Sections, 1905, p. 400. 

* Amer. Inst. Min. Eng., 1908, Bull. xxi, p. 319. 

* Prof. Paper No. 5d, U.S. Geol. Surv., 1905, p. 129, and Economic Geology, ii, 
No. 8, p. 781. 

9 A. M. Finlayson, Trans. N.Z. Inst., 1908, xli, p. 85. 


A. M. Finlayson—Ore-bearing Pegmatites of Carrock Fell. 25 


and niobates. Scheelite is also recorded from granite at Chesterfield, 
Mass., with albite and tourmaline. The scheelite occurring with 
piedmontite in a rhyolite at South Mountain, Penn.,* may also be 
pyrogenetic, while the segregations or secretions of wolframite in 
granite in the Whetstone Mountains, Cochise Co., Arizona, may be 
regarded as pyrogenetic.® 

2. Pegmatites.—From these amples it is a short step to the 
tungsten-bearing pegmatites, of which there are several types. In the 
first place, tungsten-ore occurs in pegmatites without tourmaline, as 
at Grainsgill, and similarly at Torrington, New South Wales, where 
it is associated with bismuth, monazite, fluorspar, and _ beryl.* 
Secondly, there is a wolfram-tourmaline-tin phase of pegmatites, as 
in the granite of the Southern Black Hills, where they carry 
wolframite, with cassiterite, columbite, tantalite, and tourmaline.’ 
Likewise, at Etta Knob and Nigger Hill in South Dakota, the 
pegmatites carry wolframite and cassiterite with spodumene, lithia- 
mica, albite, and orthoclase. A third type of pegmatites carries also 
iron and copper sulphides, as at Sadisdorf near Altenberg, where 
wolframite occurs with lithia-mica, fluorspar, apatite, and chalcopyrite,’ 
and in the south part of the Sierra de Cordoba, Argentina, where the 
veins contain wolframite, apatite, mica, molybdenite, pyrite, and 
chalcopyrite. Similarly, in granite near Encruzilhada, Rio Grande, 
Brazil, wolframite occurs in a quartz-vein with muscovite, pyrite, 
and chalcopyrite.? All these three types of pegmatite-veins are 
closely allied, and, further, they show clear transitions to the pneumato- 
lytic type of vein, and to the normal type of sulphide-vein. 

3. Pneumatolytic Veins.—In this well-known type the tungsten- 
ores are associated with tin a tourmaline, as in Cornwall. The 
type is also well developed in Tasmania and Northern New South 
Wales, while many of the Spanish and Portuguese occurrences are of 
this type, as at Villa Real and Castello Branco. 

4. Contact-deposits.— In some instances, tungsten-ore occurs in 
deposits of contact origin, where it is generally associated with 
characteristic silicate-minerals of the contact zone, and where replace- 
ment has generally been a factor in its formation. Thus the scheelite 
deposit of Long Hill, Trumbull, Conn.,’ appears to be of this type. 
The deposits lie in a zone between crystalline limestone and horn- 
blende-gneiss, and are associated with epidote and zoisite. Again, 
scheelite occurs in the magnetite-sulphide deposits of Pitkaranta, 
Finland, where limestones have been intruded by granite.’ In 
Tasmania, wolframite, cassiterite, bismuthinite, and molybdenite occur 


1 J. P. Iddings, Igneous Rocks, New York, 1909, vol. i, pp. 42, 68. 

2 G. H. Williams, Amer. Journ. Sci., 1896, xlvi, p. 50. 

3 F. L. Hess, Bull. 380, U.S. Geol. Surv., 1909, p. 164. 

+ Mining Journal, 1905, p. 170. 

> F. L. Hess, Bull. 380, U.S. Geol. Surv., 1909, p. 131. 

 NWig TRS Blake, Trans. Amer. Inst. Min. Enc., 1885, xii, p. 691. 

7 R. Beck, Zeits. fiir prakt. Geol., 1907, xv, p. 40. 

S Bodenbender, loc. cit., 1894, p. "409. 

° H. Kilburn Scott, Trans. Inst. Min. Eng., 1903, xxv, p. 510. 

10 ‘W. H. Hobbs, 22nd Ann. Rep. U.S. Geol. Surv., 1900— 1, pt. Mm, p- 13: 
1 Otto Tréstedt, Baudletin de la commission géologique ‘de Finlande, 1907, 1v, No. 19. 


Aion ASAT, Finlayson—Ore-bearing Pegmatites of Carrock Fell. 


in quartz-veins with fluorspar and wollastonite, in metamorphic 
Silurian limestone penetrated by quartz-porphyry.' These and other 
deposits where contact metamorphism has clearly been operative, are 
related to the other types here considered, and their mode of formation 
has been merely a local accident. 

5. Normal Fissure-veins.—Tungsten-ores are abundant in quartz- 
veins and allied deposits with sulphides and gold-ores. In the first 
place, there are many occurrences which show mineralogical transi- 
tions from the tin-tourmaline type. Examples of these are the quartz- 
veins in granite at New Ross, Lunenburg, N.S., where scheelite and 
cassiterite occur with iron and copper sulphides ;* and in the Moose 
River district, Halifax, N.S., where scheelite occurs in gold-quartz 
veins with arsenopyrite and some tourmaline. In the New England 
district of New South Wales, wolframite and scheelite occur in veins 
with cassiterite, bismuth-ores, and molybdenite im a greisen,’ an 
occurrence which should perhaps be classed as pneumatolytic. The 
Cook and Cape Yorke district of Queensland shows a marked associa- 
tion of gold-tungsten-tin ores; and in the important Herberton and 
Hodgkinson districts of Queensland, the wolframite is associated with 
molybdenite and bismuth-ores. Near Maunda, east of Nagpur, in 
India, wolframite occurs in a gold district, in bedded quartz-veins in 
mica- and tourmaline-schists.1 At the Panasquiera mines, in the 
province of Beira Baixa, Portugal, wolframite is found in quartz- 
veins with cassiterite, specularite, pyrite, arsenopyrite, and mica.’ 
Near Tirpersdorf in the Saxon Voigtland, veins in the contact-zone 
of a granite boss carry wolframite with molybdenite and tourmaline.® 
In the Predazzo district of the Southern Tyrol, veins associated with 
the post-Triassic intrusions carry scheelite, with copper-ores, fluorspar, 
arsenopyrite, and tourmaline.’ Many of these occurrences are more 
closely related to the pneumatolytic type, but they illustrate the 
impossibility, owing to the transitions, of drawing sharp dividing 
lines between one type and another. 

Turning to more normal types, these are common all over the 
world, and comprise some of the most valuable tungsten deposits. 
The ore—wolframite, hiibnerite, or scheelite—occurs in a quartz 
gangue, with the commoner sulphides, and nearly always some gold. 
In Spain, the deposits of La Sorpresa, in the province of Cordoba, 
consist of quartz-veins carrying wolframite and scheelite in granite 
and in the adjoming slate.* In the Cagliari district of Sardinia, 
scheelite occurs in quartz-veins with stibnite, a sulphide which is 
frequently associated with this ore.? The tungsten-ores of Canada 
BON H. Twelvetrees & G. A. Waller, Tasmanian Government Geological Reports, 
1 , ete. 

2 E. R. Faribault, Sum. Reps. Geol. Surv. Canada, 1908, p. 169. 

Bull. Imp. Inst., London, 1909, vii, No. 2. 
L. Leigh Fermor, Recs. Geol. Surv. India, 1908, xxxvi, p. 301. 
Mineral Industry tor 1906, xv, p. 747. 
R. Beck, Zeits. fiir prakt. Geol., 1907, xv, p. 37. 
J. Block, Sitzwngsber. der Niederrheinischen Geselisch. fir Natur- und Heilkunde 
zu Bonn, 1905, p. A, 68. 
8 Mineral Industry for 1906, xv, p. 747. 


9 Domenico J.ovisato, Atti della Reale Academia dei Lincci, 1907, ser. v, Xvi, 
Rendiconti, p. 632. 


am Uo e WH tb 


A. WM. Finlayson—Ore-bearing Pegmatites of Carrock Fell. 27 


have been described by T. L. Walker. The normal quartz-veins are 
well developed in Beauce Co., Quebec,” in various parts of the Nova 
Scotian gold-belt, and in the Cariboo and Kootenay districts of British 
Columbia. in all these occurrences the tungsten-ore is found in 
quartz-veins with gold or in gold districts. In the northern Black 
Hills of South Dakota, wolframite occurs in a zone of refractory 
siliceous gold-ores, formed by replacement of crystalline dolomite.* 
At Lane’s mine, Monroe, Conn., quartz-veins carry wolframite, often 
pseudomorphous after scheelite, together with native bismuth, pyrite, 
galena, etc. In the Snake Range, White Pine Co.,° and at Osceola,® 
both in the State of Nevada, hiibnerite occurs with scheelite in quartz- 
veins in granite. In Boulder Co., Colorado, wolframite is abundant 
in quartz-veins in a district of auriferous sulphide and telluride ores.’ 
In Arizona, wolfram-ores occur throughout the gold-belt.6 Important 
occurrences are in the Whetstone Mountains® and the Dragoon 
Mountains,’ Cochise Co. In the latter district the ore is chiefly 
hiibnerite. At Julcani, in Peru, wolframite occurs in gold-quartz 
veins in diorite.!! In Western Australia, scheelite is found at Ravens- 
thorpe, in the Phillips River Goldfield, at Kalgoorlie, and in other 
- gold districts. In New South Wales, scheelite is abundant in quartz- 
veins in and near the granite intrusions of the Cordilleran Goldfield, 
notably at Hillgrove, where the veins also carry scheelite.’ In New 
Zealand, scheelite is common in the gold-quartz veins of the Otago 
goldfield, while stibnite is another common ore in that region. The 
Otago district is one of Paleozoic slates and schists, devoid of igneous 
intrusions to which the ores might be related, but the gold-tungsten 
zone clearly belongs to the same province as the gold-belt of Eastern 
Australia. In concluding this survey of the occurrence of wolfram- 
ores, mention should be made of the common occurrence of stolzite as 
a subordinate mineral in lead-veins, and, similarly, of cupro-tungstite 
with other copper-ores. 
Conclusions.—It has been seen how tungsten may be followed 

through all stages of ore-deposition from the original magma, without 
any breaks in the sequence. It appears first in pyrogenetic minerals, 
and passes then through the different phases of pegmatites, which 
represent the end-products of the differentiated magma, and contain 
concentrations of the rarer metallic oxides. It next appears in the 
pneumatolytic veins, the first of the after-effects of the intrusion, and 
passes progressively from these, where it is associated with tin and 

1 «© Tungsten-ores of Canada’’: Dept. of Mines, Ottawa, 1909. 

2 A. R. C. Selwyn, Rep. Geol. Surv. Canada, 1893, v, p. 74 44. 

3 'T. L. Walker, loc. cit. sup., pp. 36 et seqq. 

4 J. D. Irving, Prof. Paper No. 26, U.S. Geol. Surv., 1904, p. 169. 

> F. B. Weeks, Bull. 340, U.S. Geol. Surv., 1908, p. 265. 

6 Fred D. Smith, Eng. and Min. Journ., 1902, Ixxvi, p. 304. 

7 Waldemar Lindgren, Ec. Geol., 1907, ii, p. 453. 

8 Forbes Rickard, Eng. and Min. Journ., 1904, Ixxviil, p. 263. 

® F. L. Hess, Bull. 380, U.S. Geol. Surv., 1909, p. 164. 

10 W. P. Blake, Trans. Amer. Inst. Min. Eng., 1899, xxviii, p. 543. 

1 , A. V. de Habich, Geol. Centralb., 1907, 1x, i, p. 9 (Abstr.). 

12 EK. BF. Pittman, Mineral Resources of N.S.W., Sydney, 1901, and Bull. Imp. 
Tnst., 1909, vii, No. 2. 

13 A, M. Finlaysor, Trans. N.Z. Inst., 1907, xl, p. 110; 1908, xl, p. 64. 


28 Notices of Memoirs—Dr. R. F. Scharff— 


tourmaline, to the various types of normal fissure-veins, where ‘it 
is associated with sulphides of iron, copper, and antimony, and to 
a lesser extent with lead. Throughout the sulphide zones it con- 
stantly accompanies gold. This association of tungsten with gold is 
one of the most significant facts in the occurrence of tungsten-ores. 
Mention should here be made of the occurrence of strings of gold in 
alluvial wolframite in the Ballinvalley stream, co. Wicklow, Ireland,* 
but it is possible that the gold has here been deposited on the wolfram 
by secondary action in the auriferous alluvium. 

It follows that tungsten, which is found in such a continuous series 
of vein-types, must give important evidence as to the ultimate source 
of the metals with which it is associated, and since tungsten is 
universally a product of the acid and superacid phases of magma- 
differentiation in the first place, it seems probable that it is to these 
magmatic phases that we must look for the ultimate point of departure 
of many gold- and sulphide-ores, just as in the case of tin-ores. 
While this line of evidence as to the source of gold-ores—especially 
when taken in conjunction with the authentic occurrences of primary 
free gold in granitic rocks—supports in part the hypothesis of 
Mr. J. E. Spurr,’ it is clear that the genesis of gold-ores and sulphides 
is much too complex to be thus dealt with. While magmatic 
differentiation has probably been the fundamental factor at work, 
there are many gold-ores which have probably originated during an 
intermediate or basic phase of differentiation. 

Apart from the view of derivation of ores by progressive magmatic 
differentiation, which is strongly supported by the evidence here 
discussed, there remains the problem of the origin of the vein- 
solutions. The view advocated by Mr. Spurr, that the quartz gangue 
of normal fissure-veins represents the extreme product of siliceous 
magmatic differentiation, seems to be of very limited application. 
' The views as to the origin of vein-forming solutions are still somewhat 
conflicting, but it is doubtful if any theory of vein-formation can be 
comprehensive which demands the exclusive agency of ‘ juvenile 
waters’, and which fails to recognize the work of underground 
solutions of meteoric origin in the middle and higher zones of ore- 
deposition. 

The work in connexion with this paper was carried out at the 
Imperial College of Science and Technology, London, and the writer 
is indebted to Professor W. W. Watts for advice and criticism. 


NOTICES OF MEMOTRS. 


On tHE Evipences oF A Former LAND-BRIDGE BETWEEN NortHERN 
Evrore and Norra America.? By R. F. Scuarrr, Ph.D., M.R.LA. 


(\HE author enunciated the theory some years ago that North-Western 
Europe and North-Eastern America had been connected with one 
another by land within comparatively recent geological times, and 


1 Bull. Imp. Inst., 1909, vii, No. 2, p. 171. 
2 Ee. Geol., ii, No. 8, p. 781. : 
3 From the Proceedings of the Royal Irish Academy, 1909, vol. xxviii, Section B. 


Land-bridge from Northern Europe to North America. 29 


that the reindeer had probably utilized this land-connexion in gaining 
access to Europe from its supposed American centre of dispersion. 
Further studies have led to the conviction that a second and more 
southerly land-connexion, joining Scotland, Iceland, and Greenland 
with America, must have existed in later Tertiary times. This does 
not materially alter the general principle of his original views; and 
he still adheres to the belief in a North Atlantic land-bridge between 
Europe and America during the lifetime of the reindeer. 

In 1897 Mr. W. S. Green gave us the results of his expedition to 
the Rockall Bank. Surrounded by deep water on all sides, this bank 
is of an average depth of 100 fathoms, and hes far out in the Atlantic 
to the west of Scotland. Dredging on the bank yielded only such 
shallow-water species of molluses and other marine invertebrates as 
could not have lived there under the present conditions. Moreover, 
as all the specimens were dead, it was concluded that the bank had 
only subsided to its present depth within comparatively recent times.’ 
In 1900 the Danish ‘ Ingolf’ expedition to Iceland likewise reported 
_having met littoral molluscs near the island at considerable depths 
where these animals could not possibly have lived. That such cases 
as these are due to accidental dispersal by floating icebergs containing 
shells in the ice-foot or by floating seaweeds, had been suggested ; but 
the view that the occurrence of shore forms of animal life in deep 
water implies a depression of the land seems to meet with more 
general favour, especially as no icebergs are known to stray to the 
Rockall Bank at present. 

More recently Professor Hull lays stress on the occurrence of 
channels in submerged platforms bordering the British Isles, and 
urges that they represent the drowned river-valleys and canons of an 
ancient land-surface. By means of the Admiralty charts he succeeded 
in tracing the course of the River Shannon for a hundred miles 
beyond its present mouth, right to the edge of the continental plat- 
form, while he followed the continuation of the River Erne for 
a distance of 80 miles from the Irish coast.’ 

In America similar researches have been conducted, chiefly by 
Dr. Spencer,’ but while Professor Hull advocates an elevation of the 
land during the early part of the Glacial period of 7000 to 8000 feet, 
Dr. Spencer suggests an uplift of 12,000 to 15,000 feet. A more 
cautious attitude on these oceanographic problems was adopted by 
Mr. Hudleston. He conceded that some sort of a bridge across the 
Atlantic may have existed during portions of the Tertiary era; but he 
did not believe in'an uplift beyond 2000 or 3000 feet.* 

The subject of continental shelves has lately received renewed 
attention from Dr. Nansen, and is discussed by him at great length. 
At several places, he argues, there is weighty evidence for the sup- 
position that the drowned river-valleys have been sculptured atter the 


1 W. S. Green, ‘‘ Notes on Rockall Island’”’: Trans. Roy. Irish Acad., 1897, xxxi. 

2 K. Hull, ‘‘Submerged Terraces and River Valleys’’: Trans. Vict. Inst., 1897, xxx. 

3 J. W. Spencer, ‘‘ Submarine Valleys”: Bull. Geol. Soc. America, 1903, xiv, 
p. 224. 

4 W. H. Hudleston, “‘ Eastern Margin of North Atlantic Basin’’: Gzox. Mac., 
1899, p. 148. 


5 | ae Notices of Memoirs—Dr. R. F. Scharff— 


formation of the continental shelves. The latter consequently have 
been dry land after their formation.’ 

The remarkable circumstance that the submarine fjord-valleys on 
the European and on the American side, and likewise the submarine 
ridges connecting the two continents, are situated at about the same 
depth makes it probable that the whole area had once been raised 
simultaneously, and had thus become connected by land. Dana long 
ago urged that the refrigeration of the climate at the close of the 
Tertiary era was connected with a period of high-latitude elevation,” 
and I cannot refrain from expressing my opinion, that the Glacial 
period was primarily due to the diversion of oceanic currents produced 
by changes in the distribution of land and water. With every respect 
for the views of those who hold different opinions, it seems to me that 
the peculiar phenomena connected with the Ice Age in Western Europe, 
and especially the apparent survival of southern species of plants and 
animals in Ireland through the Glacial period, are best explained by 
such a theory as that just stated. 

It is especially the teachings of Edward Forbes and A. R. Wallace 
that led to the recognition of the significance of the present geographical 
distribution of animals and plants as an indicator of the changes which 
have taken place in the arrangement of land and water. They believed 
that many terrestrial animals and plants require a continuous land- 
surface for their dispersal. Yet the diversity and comparative richness 
of the fauna and flora of some of the oceanic islands, and the depth of 
water intervening between them and the mainland, had to be accounted 
for in some other manner. Neither Wallace nor Darwin was inclined 
to admit extensive geographical changes within the period of existing 
species. The distribution of plants and animals by ‘ accidental’, or 
what Darwin called ‘ occasional’, means of dispersal seemed to furnish 
them with a clue to the worldwide dissemination of certain species. 

Darwin’s experiments have found many imitators; and valuable 
observations tending to show that at any rate some of the more 
minute animals and plants are liable to be conveyed by occasional 
means of dispersal, have been made. 

It would be idle to deny that the seeds of certain plants are carried 
to great distances by wind; that many others are undoubtedly trans- 
ported by ocean currents; that some seeds are even scattered here and 
there by birds. My contention is, and, I concur in this opinion with 
many eminent botanists, that only a small percentage of plants are 
disseminated and actually established in that manner. Most of them 
require for their dispersal a solid and continuous expanse of soil. 

Sir Joseph Hooker evidently believed that the flora of Greenland 
had travelled across from Europe by a land-bridge in Pre-Glacial 
times. He considered the existing plants of the country as certainly 
older than the Glacial period; for he argued that the severity of the 
climate destroyed many species, while the remainder took refuge and 
survived in the southern parts of Greenland.’ Professor James Geikie 


1 F. Nansen, Norwegian North Polar Expedition, 1904, iv, p. 192. 

2 J.D. Dana, Manual of Geology, 3rd ed., p. 540. 

3 J. D. Hooker, ‘‘ Distribution of Arctic Plants’’: Trans. Linn. Soc., 1860, 
XXili, pp. 252-5. 


Land-bridge from Northern Europe to North America. 31 


maintains that a land-connexion between Greenland, Iceland, the 
Farodes, and Scotland, must have existed, because the plants could 
only have migrated from Europe over a land surface,! but to him the 
idea of a survival of plants during the Ice Age in Greenland is 
inconceivable. He therefore argues that the land-bridge could only 
have existed in Post-Glacial times. Hence the Glacial period and its 
supposed adverse influence upon the flora of Northern Europe has now 
become the mainspring of most speculations as to the former presence 
or absence of a northern land-bridge. 

The question of the supposed survival of plants through the Ice Age 
in Greenland largely depends on the problem whether or no the glaciers 
of that country had a vastly greater extension formerly than they have 
at present, and covered the whole of the land now free from ice. That 
the latter has never been entirely invaded by ice has been clearly 
demonstrated by the leader of the German Greenland Expedition, 
Dr. E. von Drygalski. The greater extension of ice in former times 
no doubt can be proved, he remarks; yet glaciers certainly never 
reached the cliffs and rock-pinnacles which abound on all parts of the 
coast-lands of Greenland.” No reason, therefore, can be adduced why 
the flora of Greenland should not have survived the Ice Age in that 
country, particularly as we have some grounds for the supposition that 
the land in the Arctic regions then stood higher than it does now. 

It would be wrong to suppose that plant migration to the Farves 
and Iceland has proceeded altogether from Europe. A stream has 
likewise advanced from the opposite direction. ‘hus in the Farées 
we find at least seven plants unrepresented in the British Islands. 
These came from Greenland and Arctic America. 

A small group of plants is of particular interest to Irish botanists, 
as being almost exclusively confined to the West of Ireland and North 
America. According to Messrs. Colgan & Scully,? the plants in 
Ireland which belong to this group include Spiranthes Romanzoviana, 
LErtocaulon septangulare, and Naias flexilis. All of these plants are 
indigenous and discontinuously distributed. An interval of more than 
200 miles separates the northern and southern stations in Ireland of 
the rare orchid S. Romanzoviana. The water plants L. septangulare 
and JV. flexilis inhabit not only some of the western Irish lakes, they 
occur also in Scotland. 

Messrs. Colgan & Scully do not explain the presence in Ireland of 
these plants as being due to any such accidental transport. They 
believe them to have reached Europe by means of an ancient northern 
land-connexion. Mr. Praeger likewise comes to a similar conclusion 
with regard to the origin of the American plant group in Ireland. 
He does not favour the theory of accidental dispersal. A land surface, 
long since destroyed, of Pre-Glacial age, appeals to him as a more 
likely explanation of the presence of the American plants.‘ 

The number of plants common to Europe and North America is 
really far greater than we imagine, though very few, as we have seen, 


' James Geikie, Prehistoric Hwrope, 1881, p. 520. 

2 EK. von Drygalski, Grénland Expedition, 1897, vol. i, p. 335. 

3 N. Colgan & R. W. Scully, Cybele Hibernica, 1898, 2nd ed., p. 71. 
4 R. Lil. Praeger, Irish Topographical Botany, 1901, p. 23. 


o2 Notices of Memoirs—Dr. R. F. Scharff— 


are quite confined to these continents. Of those which also occur in 
Asia there are many, like the Orchid Lestera cordata, which grows only 
in a few localities in the extreme east, that are apparently absent from 
the greater part of the continent. It is probable that all these have 
found their way from America to Europe by a direct passage. 
Moreover, we know from Professor Drummond’s researches that of 
seventy species of fossil plants observed by him in the Pleistocene 
clays of Toronto in Canada, twenty occur at the present day both in 
that country and in Europe.'' This seems to indicate that during the 
Pleistocene period, the great mass of the flora common to America and 
Europe had already found its way from the one continent to the 
other. 

The zoological testimony in support of this view is of a more 
pronounced character. The interest aroused in Ireland by the 
discovery of the American plants has led to research in other 
directions. Thus, in 1895, three species of freshwater sponges were 
detected in various lakes at some distance from the sea on the west 
coast. Only one of these sponges, viz. Zubella pennsylvanica, has since 
been observed in another European locality, in Loch Baa in Scotland, 
but all of them are identical with American species.” Dr. Hanitsch 
identified them as Hphydatia crateriformis, Heteromeyenia Ryder, and 
Tubella pennsylvaniea. 

In my more recent work on European Animals, I have incidentally 
dwelt on the past range of the Great Auk (Alea impennis) as indicating 
the presence of a former more continuous coastline between the 
British Islands, Iceland, Greenland, and Newfoundland, in all of 
which countries this bird was known to have been abundant.® Yet, 
after all, the best evidence in favour of a North Atlantic land-bridge 
is furnished by the invertebrates. Our special attention is drawn by 
Mr. Born to the importance of the ‘Running Beetles’ of the genus 
Carabus. From the fact of their being wingless and usually found 
under stones or clods of earth, they are not liable to be transported 
accidentally by any of the means usually supposed to aid animals in 
their dispersal. Mr. Born claims that at least two European species 
of Carabus, viz. C. catenulatus and C. nemoralis, have crossed the 
Atlantic by means of an ancient land-bridge. A third form— Carabus 
groenlandicus Chamissonis—seems to have originated in America, and 
to have travelled from there to Greenland and Lapland.* 

Of another group of insects—the Collembola—Professor Carpenter 
remarks: ‘(It is of interest to find that the presence of not a few 
species of these wingless insects in America, in Greenland, in the 
islands to the north of Europe and Asia, and on the Euro-Asiatic 
continent, lends support to our belief in a Pliocene or Pleistocene 


1 A. T. Drummond, ‘‘ Plants common to Europe and America’’: Natwre, 1904, 

Ixx, 55. 
oh Hanitsch, ‘‘ Freshwater Sponges of Iveland’’: Zrish Nat., 1895, iv, p. 126. 

Aer endate, “© Freshwater Sponges in Scotland’? : Journ. Linn. Soc. (Zool.), 
1908, xxx. 

3B. FB, Scharff, Luropean Animals, 1907, pp. 37-9. 

4 Paul Born, ‘‘Carabologische Studien”: Entomol. Wochenblatt, 1908, xxv, 
PD: oye 


Land-bridge from Northern Europe to North America. 38 


land-connexion to the north of the Atlantic Ocean—a belief already 
upheld by so much evidenee, both geological and zoological.”’ ! 

Quite a number of naturalists believe that any resemblance between 
the European and the American fauna must have arisen, not from any 
direct intercourse between Europe and America, but by a migration 
across Asia and a Bering Strait land-connexion. The supposition of 
an ancient northern Pacific land-bridge presents fewer difficulties 
to them than the Atlantic one, and is preferred for that reason. 
Dr. Horvath, for example, who states that no less than 128 species of 
Hemiptera are common to the two continents, argues that they all 
must have crossed Asia in reaching the one from the other.? But he 
and those who agree with him were apparently unaware that certain 
freshwater species common to Kurope and America are almost totally 
absent from Asia or Western America. 

Let us take, for example, our common Perch (Perca fluviatilis), 
a variety of which also inhabits North America. It is absent not 
only from a large part of Asia, but also from Western North America. 
Certainly this looks like a case of direct migration from America to 
Europe. 

Another example that I have had occasion to quote in my work on 
European Animals (p. 35) is the freshwater Pearl-Mussel (Deleagrina 
margaritifera). On our continent it inhabits the British Islands except 
Kastern England, the mountain streams of Scandinavia, and the hill- 
region of Central Europe except the Alps. Far to the east it reappears 
in a different form in the River Amur in Eastern Siberia, in the 
island of Sakhalin, and in Kamchatka. Another variety is met with 
across the Bering Strait in Alaska and in Western North America 
generally. The type form occurs in the Quebec province of Canada, 
in the Lower Saskatchewan River, and in New England. The 
typical freshwater Pearl-Mussel is only met with in Eastern North 
America and in Central and North-Western Europe. America is 
undoubtedly its original home. From it the mussel spread to Europe 
in an eastward direction, and not by way of Asia. As the fry of these 
mussels attach themselves to the gills of fishes, they are liable to wide 
dispersal within at least one river system; but fishes in this case 
could scarcely have aided them in reaching Europe. A land-connexion 
between the two continents explains their distribution certainly better 
than any other theory. 

The most striking piece of evidence we possess in favour of a Pre- 
Glacial land-connexion between North-Western Europe and North- 
Eastern North America is the presence in the latter country of the 
snail Helix hortensis. 

A western species in Europe, Helix hortensis, is remarkable for its 
extensive northern range. It occurs in Scandinavia, all over the 
British Islands, in the Shetlands and Farées, and even in Iceland. 
It is altogether absent from Asia. Its occurrence in Southern 


1G. H. Carpenter, ‘‘ Collembola from Franz Joseph Land’’: Proc. R. Dublin 
Soc., 1900, ix, p. 276. cS 
2 G. Horvath, ‘‘ Faunes hémiptérologiques’’: Ann. Hist. Nat. Mus. Hungarici, 
1908, iv, pp. 4-7. 
DECADE V.—VOL. VII.—NO. I. 3 


o4 Notices of Memoirs—Dr. R. F. Scharff— 


Greenland had generally been attributed to a recent human intro- 
duction; but it has been taken in several different localities, and 
we must, I think, look upon it as an indigenous species. During 
the year 1864 Professor E. 8. Morse discovered the shell of this snail 
among ancient ‘kitchen-middens’ on some of the islands off the coast 
of Maine. This fact led him to consider that the snail had wandered 
along some ancient coastline from the Old World across the North 
Atlantic. Dr. Binney, and more recently Professor Cockerell, con- 
curred with Professor Morse’s opinion, while the Rev. Mr. Winkley 
even suggested that Helix hortensis arrived in North America before 
the advent of the Glacial period. With the latter theory Mr. Johnson, 
another conchologist, expressed his agreement; and it is to his paper 
that I am indebted for the above-mentioned information.? 

All doubts as to the claim of Helix hortensis being an indigenous 
American species are now set at rest through the discovery by Dr. Dall 
of the shell of this snail in undoubtedly Pleistocene deposits in the 
State of Maine.? Moreover, the species is now known to inhabit 
a much greater area than was formerly supposed; for if has been 
collected in Labrador, Newfoundland, Prince Edward Island, and 
many other small islands where it could not possibly have been 
brought by man. It may, therefore, be considered as definitely 
established that JZelix hortensis reached America in Pleistocene or 
Pliocene times without human intervention. 

The discovery of Helix hortensis in Greenland is an important factor 
in favour of the land-connexion theory. That this species should 
have survived the Glacial period in that country need not surprise 
us; for several other species of land and freshwater molluscs certainly 
must have done so. Planorbis arctica, Limnea Vahli, L. Wormskioldi, 
Suceinea grenlandica, Vitrina angelica, Pupa Hoppirt, and Conulus 
Fabricti are almost all confined to Greenland, and no doubt originated 
there in Pre-Glacial times. 

Of all the theories which have been advanced in explanation of the 
occurrence of identical species on both sides of the Atlantic Ocean, 
only the following three have met with wide approval :— 

1. Migration from Europe across Asia and a Bering Strait land-bridge to 
America or vice yersa. 


2. Occasional transport by birds across the Atlantic Ocean. 
3. Migration across a direct Atlantic land-connexion. 


If we consider the zoological evidence alone, namely, the absence of 
Helix hortensis from Asia and Western America, the distribution 
of the Perches and the freshwater Pearl-Mussel, and that of the 
freshwater Sponges, the first of the three hypotheses is scarcely 
applicable to these instances of distribution, and does not, therefore, 
explain the presence of identical species on both sides of the Atlantic 
in a satisfactory manner. 

As regards the supposed conveyance by birds of seeds and in- 
vertebrates across the same ocean, the second theory must be 


1 C6. W. Johnson, ‘‘ Distribution of Heli hortensis”’?: Nautilus, 1906, xx, p. 73. 
2 W. H. Dall, ‘‘Land and Freshwater Mollusks’’: Harriman Alaska Exped., 
1905, xiii, p. 20. 


Land-bridge from Northern Europe to North America. 35 


applicable to a transport in two directions, both from America to 
Europe as well as vice versa. 

The fact that both in America and Kurope the indigenous species of 
plants and animals identical to the two continents are largely confined 
to the coast region may appear at first sight in favour of the theory of 
introduction by birds. Almost all the American plants, and all the 
American freshwater sponges at any rate, occur in the vicinity of the 
coast. It has been argued, therefore, that, after their long flight 
across the ocean, birds would naturally alight on the earliest 
opportunity; and that it was for this reason that the plants and 
animals common to the two continents were so largely confined to the 
coastal districts. But from what has been mentioned we have no 
reason to infer that American birds do habitually alight on the west 
coast of Ireland on first reaching Europe. It seems highly probable 
that they cross by way of Greenland. We should, therefore, expect 
all species of the invertebrates and plants common to the two 
continents to be found in Greenland as well. This is not so. Only 
comparatively few of them are met with in Greenland. The theory 
that the resemblance in the fauna and flora of Eastern North America 
and Western Europe is due to the action of birds is, I think, not 
supported by sufficient evidence. 

The third theory, that the identical species on either side of the 
Atlantic Ocean are the result of a direct land-connexion between 
Scotland, Iceland, Greenland, and Labrador, appears to me to be well 
founded on geological, bathymetrical, and biological evidence. No 
decisive testimony, however, has as yet been brought forward to show 
during what geological period this land-bridge was formed and how 
long it lasted. The assumption that such geographical conditions 
prevailed during early Tertiary times is very widespread. That this 
state continued during the Miocene period is likewise maintained by 
many; though Professor Dawkins and a few others do not admit the 
existence of the northern land-bridge in Pliocene or more recent times. 
Sir Archibald Geikie’s researches point to the production of the great 
basalt plateaux of North-Western Europe in early Tertiary times. 
These plateaux formed a continuous tract of land, as far as the Farodes 
at any rate. He proves that in many places, such as Iceland, the 
Faroes, and the West of Scotland, enormous subsidence subsequently 
took place.’ 

Once we admit that animals and plants were able to survive the 
Glacial period in northern latitudes, a land-connexion such as suggested 
in Pliocene times would readily account for the presence of all the 
animals and plants common to Europe and America. By many of 
those best able to judge, an admission to that effect has been made. 
Pliocene deposits are scanty in the British Islands; yet they yield 
valuable suggestions as to the geographical conditions of the North 
Atlantic. An examination of the fossil invertebrates contained in the 
St. Erth Beds in Cornwall, which are of Pliocene age, showed that 
the fauna possessed a remarkably southern facies, and that there was 

1 W. Boyd Dawkins, Zarly Man in Britain, 1880, p. 43. 

2 A. Geikie, ‘‘ Basalt Plateaux of North-Western Europe’’: Q.J.G.S., 1896, lii, 
p. 405. 


36 Notices of Memoirs—Dr. R. F. Scharff. 


a total absence of boreal or Arctic species. This fact led Professor 
Kendall and Mr. Bell to the conclusion that at the period during 
which these deposits were laid down—that is to say, during the latter 
part of the Pliocene period—no channel or direct communication 
existed between the North Sea and the Atlantic Ocean, the Straits of 
Dover being closed in the south, while in the north the Tertiary 
volcanic chain formed a barrier across from the North of Scotland to 
Greenland by way of the Shetland Islands, Fares, and Iceland.? 

Mr. Reid’s contention that the St. Erth Beds are older than Messrs. 
Kendall & Bell estimated—that they are, in fact, of early Pliocene 
age—is founded chiefly on the circumstance that the percentage of 
extinct species is about the same as that of the Coralline Crag. The 
consideration of the supposed climatic conditions does not seem to me 
of any particular value; and, as he remarks, the exact age of the 
clays is still doubtful.* Even if the St. Erth Beds belong to the lower 
Pliocene, there are no grounds for the supposition that the northern 
barrier, alluded to by Messrs. Kendall & Bell, had ceased to exist in 
later Pliocene times. 

The change in the Pliocene fauna of the east coast of England, 
as we pass from the older to the newer beds, no doubt implies, as 
Mr. Harmer pointed out, an opening up of the area to the influence 
of the northern seas. But we do not possess the slightest evidence 
for the assumption that the Atlantic Ocean was similarly affected. 
Many of the facts, indeed, lead to the conclusion that the land on the 
Atlantic coasts of the British Islands stood highest in late Pliocene 
and early Pleistocene times, and that it was then that Helix hortensis 
and many other European species must have made their way to 
America. 

Glacial conditions prevailed at this time on all the high mountain 
ranges surrounding the warm Atlantic Ocean, and yet the coast region 
must have supported an abundance of animal and plant life. The 
presence of a land-bridge between Scotland and North America by 
way of Greenland, and another between England and France, would 
have excluded the Gulf Stream from the Arctic regions. Professor 
Blytt’s argument that under such conditions all the coast region, 
including Iceland and Southern Greenland, would have had a higher 
temperature than at present, while the lands beyond were probably 
colder, seems irrefutable. Yet Professor James Geikie believes that 
even the latter countries would then have had a more genial climate.° 

In my opinion it was during this epoch, in Pre-Glacial times, that 
the interchange between the fauna and flora of North-Western Europe 
and North-Eastern America was effected across the northern land- 
bridges. 

Only one other point needs to be commented upon. I have shown 


1 Pp. F. Kendall & A. Bell, ‘‘ The Rose Beds of St. Erth’’: Q.J.G.S., 1886, 
xhi, pp. 206, 207. 
2 C. Reid, Pliocene Deposits of Britain, 1890, p- 61. 
3 F. W. Harmer, ‘* Pliocene Deposits of Holland” : Q.J.G.S., 1896, lii, p. 754. 
& Abel Blytt, ‘ Theorie d. wechselnden Klimate”? : Engler’s Botanische Jahré., 
1881, ii, p. 49. 
5 James Geikie, Prehistoric Europe, 1881, p. 520. 


Reviews— Geological Survey of Great Britain. ov 


that most of the American species occupy the Atlantic coast region in 
the British Islands. Almost all the southern or Lusitanian species 
are found in precisely the same area in England, Ireland, and Scotland. 
This seems to me partly due to the fact that the temperature was 
considerably higher there during the Glacial period than in the more 
inland localities. Even now the plants are under more favourable 
climatic conditions on the west coast than further inland, and less 
exposed there to competition with the stronger eastern rivals. More- 
over, almost the whole of Ireland and a large portion of England are 
thickly swathed in a mantle of Glacial clay. We can only suppose 
that the forces which controlled the deposition of this clay were less 
effective on the west coast, which may have extended far to the west 
of its present boundary, and have thus given rise to the preservation of 
many species of animals and plants which were destroyed elsewhere. 


REVIEW S.- 


——_>——_ 
I.—GroLtocgicaL Survey or Great Briratn. 


1. Tuer Grotocy oF tHE Seaspoarp or Mrp ARGYLL, INCLUDING THE 
Istanps oF Lurne, ScaRBA, THE GARVELLACHS, AND THE LESSER 
IsLESs, TOGETHER WITH THE NORTHERN PART OF JURA AND A SMALL 
portion oF Mutt. By Dr. B. N. Peacu, F.R.S., H. Kynasrton, 
and H. B. Murr [Mavre|; with contributions from S. B. 
Witxinson, J. S. Grant Watson, J. B. Hitt, A. Harker, F.R.S., 
E. B. Bartey, and petrological notes by Dr. J. 8. Frerr. 8Vvo; 
pp. vii, 121, with 7 text-illustrations and 8 plates. Glasgow, 1909. 
Price 2s. 3d. 

E cannot refrain from a feeling of sympathy with librarians, who 
give cross-references in their catalogues, at the lengthy title 

and array of authors and contributors imprinted in this memoir. The 
field-work, however, has been carried out by many hands in a very 
diversified region, comprising a number of islands and parts of 
islands, together with the western seaboard of Argyllshire, from 

Easdale and Kilmelfort on the north, to the plateau beyond the 

Crinan Canal on the south. 

Nearly the whole of the area described is made up of various 
metamorphic rocks, including the Craignish and Ardrishaig Phyllites, 
the Easdale Slate and Limestone Group, and the Quartzite Group, 
together with epidiorites. No less than fifty-two pages are given to 
the description of these rocks, and of the folding, metamorphism, 
the crush-conglomerates, and thrust-planes; while the subject is 
illustrated by remarkable photographs of pseudo-conglomerate and 
strain-slip cleavage, of folds, boulder-beds, and phacoids of epidiorite. 

Rocks of Lower Old Red Sandstone age occur on the mainland north 
of Loch Melfort, and in the islands of Seil and Lunga; and they 
consist mostly of andesitic lava-flows, with here and there some 
shales, grits, and conglomerates, as well as tuffs and agglomerates. 
There occur also masses of diorite and granite, together with dykes 
and sills of other intrusive rocks, and these, with the effects of contact 
metamorphism, are duly described. 


38 Reviews—Geological Survey of Great Britain. 


Brief reference is made to the Tertiary igneous rocks of Mull, which 
comprise basaltic lavas, for the most part amygdaloidal, and intrusive 
sills of olivine-dolerite, that make strong features and possess columnar 
jointing. Dykes of Tertiary dolerite and basalt are numerous 
throughout the entire area; and these, which are described in some 
detail, include teschenites, tholeiites, andesitic pitchstone, and camp- 
tonite. Altogether, with the chapters on Old Red and Tertiary rocks, 
the petrographical portion of the memoir extends over eighty pages. 

The higher grounds on the mainland, though glaciated, are com- 
paratively free from superficial deposits, but evidence is given of the 
westerly seaward passage of an ice-sheet, which at one time filled the 
sounds and sea-lochs and overrode the outer islands, rising in Scarba 
and Jura in places to a greater height than any part of the mainland. 
Numerous small freshwater lochs occupying rock-basins owe their 
origin to the ice-erosion. 

Raised beaches indicate that the area has undergone periodic 
elevation since Glacial times to the extent of about 100 feet; but it 
is mentioned that the contour-lines, which are continued ‘‘to a depth 
of 200 feet below Ordnance datum level, show that the floors of the 
different sea-lochs, and of the Sounds of Luing, Shuna, and Seil are 
studded with basins which, were the land upheaved to the extent of 
200 feet, would form lochs much larger in area than any existing on 
the present land surface ”’ 

The inference is that the land was elevated to that extent or more 
during the Glacial period, and subsequently depressed, so that despite 
the final elevation of 100 feet, indicated by the Raised Beaches, ‘‘ the 
promontories, islands, and skerries represent the hill-tops and dividing 
ridges between the drowned valleys.” 

The chapter on economics contains an important account by 
Mr. Maufe of the roofing-slates of Easdale, which have been syste- 
matically worked since 1748. It is interesting to note that while 
most of the best slates are characterized by small cubes of pyrites, 
some of the slates in which the iron sulphides are in a finely 
disseminated state are liable to decay. 


2. THe Grotocy or tHE Sourm Watzs Coat-rrecp. Part I: Tun 
Country arounD Newport, Monmourusuire. By Ausrey Srrawan, 
Se.D., F.R.S. Second Edition. 8vo; pp. x, 115, with 6 text- 
illustrations and 1 plate. London, 1909. Price 1s. 6d. 


\EN years have elapsed since we called attention (Gzot. Mae., 1900, 
p. 86) to the first edition of this memoir, which was also the first 
publication relating to the re-survey of the geology of the South 
Wales Coal-field. “The six- inch survey of the. great coal-field, com- 
menced in 1891, has been conducted and now ‘completed under the 
personal superintendence of Dr. Strahan. 

In this second edition of the Newport memoir the geological infor- 
mation relating to the area has been brought up to date ; and of 
especial importance are the records of new coal-borings. A useful 
map has been added showing thicknesses of the Pennant Grit and 
Lower Coal Series at different localities. 

In the former edition of the memoir attention was called to the 


. 


Reviews— Cretaceous in Poland. 39 


sharp plane of demarcation between the Silurian and Old Red Sand- 
stone. It is now known that the Tilestones (passage-beds) and 
underlying minor Silurian divisions, met with 40 miles further west, 
are not present in the Usk district, unless represented by strata of 
wholly different characters. The list of Silurian fossils has been 
revised, and the nomenclature in the earlier edition modified in a way 
that may be said to render comparisons odious. 

The Old Red Sandstone is now separated into Upper and Lower 
divisions, with the Brownstones in the upper part; but no evidence 
of unconformity in the formation has been detected. 

Some observations have been made by Mr. E. E. L. Dixon on the 
zonal divisions in the Carboniferous Limestone of the Newport area, 
and the absence of the higher portions of the Limestone Series is 
attributed to the unconformable overstep of the Millstone Grit. 


I].—Creraceous oF Ponanp. 


\ROM a series of papers extracted from osmos (Lemberg), 1909, 
vol. xxxiv, we gather that Jan Nowak describes the Cephalopod 
fauna of the uppermost Senonian (Campanian) of the Carpathians. 
The fauna was collected by Professor R. Zuber in Galicia and includes 
such well-known forms as Baculites anceps, Lam., Scaphites constrictus, 
Sow., S. tenuistriatus, Kner, and Belemnites bipartitus, Bl. With 
these occurs a form called ‘‘ Znoceramus Cripsi, Mant.” This unfor- 
tunate species seems to give endless trouble to Continental authors, 
and it may as well again be stated that the type in the British Museum 
is an internal cast, without any shell whatever, and came from the 
Chalk Marl of Offham. In England it is certainly a Cenomanian 
fossil, and there is nothing like it in the higher beds. Dr. Zuber 
describes the stratigraphy and tectonics of the Galician Carpathians in 
the same volume, and after an appropriate summary of previous 
authors, gives a lucid sketch of the geology, illustrated with many 
sections. But here also Znoceramus Crips? is associated with Belemni- 
tella mucronata, which seems an impossible thing to those who know 
the fauna of the Chalk of England. Dr. W. Rogala, who discusses 
this very point in a communication to the same volume, says on 
p-. 742 of his paper: ‘‘ Wszystkie formy z Lopuszki W. dadza sie 
pomiesoic w obrebie gatunku Jnoceramus Cripsi, Mant., jaki temu 
gatunkowi nadal Zittel. Nowsze jednak badania Petraschecka 
wykazuja, ze formy gosawskie sa weale rozne od oryginalu Mantell a, 
a badania J. Bohma wykazuja rowniez, ze i formy Goldfussa sa od 
niego rozne; wobec tego obydwaj ci autorowie nazwe J. Cripsi, 
Mantell zaciesniaja, a liozne formy dotychezas nia obejmowane 
oddzielaja jako osobne gatunki,” and omits Z. Crips’, Mant., from his 
list on p. 745, using the name J. (cf.) regularis, d’ Orb., instead. 

Other interesting papers in this volume are on the fish fauna of the 
menilit-beds (Lower Oligocene) of the Carpathians, by Jan Rychlioki, 
and one on the Titonian Klippen at, Kruhel Wielki, near Przemysl, by 
Dr. Zuber. These seem to be composed of foundered Inoceramus-bed, 


with exotic blocks of Stramberger Titonian. 
Ce DES: 


40 Reports and Proceedings—Geological Society of London. 


RAP OonrtsS AND LROchE DENG TS. 


November 17, 1909.—Professor W. J. Sollas, LL.D., Sc.D., F.R.S., 
President, in the Chair. 


The following communications were read :— 

1. ‘The Geology of Nyasaland.’ By Arthur R. Andrew, F.G.S., 
and T. Esmond Geoffrey Bailey, B.A., F.G.S. With a Description of 
the Fossil Flora, by E. A. Newell Arber, M.A., F.G.S.; Notes on the 
Non-Marine Fossil Mollusca, by Richard Bullen Newton, F.G.S.; and 
a Description of the Fish-Scales of Colobodus, etc., by Ramsay Heatley 
Traquair, M.D., F.R.S., F.G.S. 


(1) The greater part of Nyasaland consists of crystalline rocks, 
which comprise— 

(a) Highly metamorphosed sedimentary beds, including 
graphitic gneisses with limestone, and muscovite-schists. 

(6) Foliated igneous rocks, especially augen-gneiss, derived 
from granite or syenite. 

(c) Plutonic intrusions, usually granite or syenite, more 
rarely gabbro. In two localities nepheline and _ sodalite- 
syenites are found; these are perhaps of the same age as the 
similar post- Waterberg and pre-Karoo syenites of the Transvaal. 


(2) In the north-western corner of Nyasaland is a somewhat altered 
sedimentary series, which forms the Mafingi Hills. It consists of 
a thick accumulation of quartzites, grits, and sandstones of pre- 
Karoo age. 

(3) The Karoo System is represented both in the north and in the 
south of Nyasaland; in the north it occurs in patches, which owe 
their preservation to faulting. It has afforded remains of freshwater 
lamellibranchs (Paleomutela), fish-scales (Colobodus), and species of 
Glossopteris. 

(4) Recent lacustrine marls and sands are found at great heights 
above the present level of the lake, and as much as 15 miles away 
from its margin. 

(5) Pumiceous tuffs, associated with recent gravels containing 
pebbles of Tertiary lava, are found in the extreme north of the 
country; across the border, in German East Africa, Tertiary and 
recent lavas and tuffs are widely distributed. 

(6) Nyasaland consists of high plateaux rising irregularly one above 
the other. The Nyika and Vipya plateaux were doubtless at one time 
continuous as ‘‘a platform of erosion’’, which originated after the 
main faulting of the Karoo in Northern Nyasaland, and before the 
formation of the great Nyasa fault trough. 


2. ‘*The Faunal Succession of the Upper Bernician.” By Stanley 
Smith, M.Sc., F.G.8. 

The Bernician Series forms the upper and by far the larger division 
of the Lower Carboniferous sequence of Northumberland, and covers 
the greater part of the county. Below the Bernician lie the Tuedian 


Reports and Proceedings—Geological Society of London. 41 


Beds. The Northumberland succession, together with the Lower 
Carboniferous rocks north of the Tweed, occupies the northern ex- 
tremity of the Pennine Province of the Carboniferous Limestone Series, 
which stretches from Staffordshire into Scotland. The Carboniferous 
strata in Northumberland encircle the Cheviots on the south, east, 
and north, and dip from the volcanic inlier, so that the general strike 
forms a rough semicircle round the igneous massif, nearest to which 
consequently lie the lowest beds. 

The Bernician is mainly built up of sandstones and shales, but inter- 
calated among the arenaceous and argillaceous deposits are the various 
beds of limestone and numerous seams of coal. 

In the Upper Bernician, the limestones are fairly thick, are constant, 
and are truly marine. The calcareous beds of Lower Bernician age 
are thin and impure, and frequently contain St:gmaria and other 
plant-remains. There are a few good marine limestones, but these 
are of local occurrence. 

The Upper Bernician, taking the Redesdale Ironstone Shale as the 
base, answers to Tate’s Calcareous Group; while the Lower Bernician 
is equivalent to Tate’s Carbonaceous Group. 

It is with the Upper Bernician only that the present paper {is 
concerned. 

The whole of the Upper Bernician Limestones belong to the 
Dibunophylium-zone, but they are capable of the following palzonto- 
logical subdivisions :-— 


a = Redesdale Ironstone Shale. 
Shallow-water fauna, mainly lamellibranchs ; corals rare. 
Dibunophyliun near 6 has been found. 

I = Redesdale Limestone. 
D 1 fauna. 
Dibunophyllum @. 
Carcinophyllum @ especially characteristic. 

II = Fourlaws and Oxford Limestones. 
D 2. 
Lonsdalia floriformis enters. 
III = Kelwell, Acre, and Four Fathom Limestones. 

D 2-3 presents in its main character a Zaphrentid phase. 


IVa = Great and Little Limestones. | 


2 


Oe 
Dibunophylhun muirheadi. 
Koninckophyilum magnificum. 
Diphyphyllum dianthoides. 


IVd = Corbridge, Thornbrough, and Robsheugh Limestones. 
The tendency in the Dibunophyllids towards Aspidophylloidal structure 
reaches its highest development. 


1Ve = Fell Top Limestone. 
Characterized by the presence of Dibunophyllum muirheadi mut., cf. 
Dibunophylium y, and Phillipsastrea radiata. 


3. ‘Notes on the Dyke at Crookdene (Northumberland), and its 
Relations to the Collywell, Morpeth, and Tynemouth Dykes.” By 
Miss M. K. Heslop, M.Sc., and Dr. J. A. Smythe. (Communicated 
by Professor G. A. Lebour, M.A., D.Sc., F.G.S.) 

The dyke at Crookdene is exposed in the bed and banks of the 


42 Reports and Proceedings—Geological Society of London. 


Wansbeck about 15 miles above Morpeth. It is intruded along 
a fault-fissure in beds of Bernician age, and apparently comes to 
a natural head. The basalt is characterized, microscopically, by 
narrow lath-shaped felspars and curved augites. Macroscopically, 
its most interesting feature is the occurrence of large inclusions of 
a felspar, which is shown by chemical analysis to be closely allied 
to anorthite. The exterior of the inclusions in contact with the 
ground-mass is strongly zoned, the latter showing a slightly chilled 
edge; the individual crystals are intergrown and are cracked, faulted, 
and in places completely shattered. In no case is the dislocation 
great, and, in fact, the crystals seem to have burst in situ. These 
phenomena point to a plutonic origin of the felspathic inclusions and 
connect them with the porphyritic felspars of the Tynemouth 
Dyke, for which a similar origin has already been suggested by 
Dr. Teall. 

The dyke which comes to a head in the coast-section at Collywell, 
about 24 miles distant, shows almost precisely the same peculiarities. 
Chemical and microscopical examination of the two basalts and their 
felspathic inclusions show them to be practically identical. Con- 
sidering these facts and the general field-relationships of the dykes, it 
appears probable that they belong to the same intrusion. 

The work of Dr. Teall upon the dykes at Tynemouth and Morpeth 
has been amplified by further observations. The resemblances among 
the four dykes are so strong as to render it probable that they are 
derived from a common source. The observed differences are such as 
could be readily accounted for by differences of physical condition 
operating during the period of consolidation of the dykes. 


December 1, 1909.—Professor W. J. Sollas, LL.D., Sc.D., F.R.S., 
President, in the Chair. 


The following communications were read :— 

1. ‘‘The Tremadoc Slates and Associated Rocks of South-East 
Carnarvonshire.”” By William George Fearnsides, M.A., F.G.S., 
Fellow of, and Lecturer in Natural Sciences at, Sidney Sussex 
College, Cambridge. 

This paper gives the results which have been obtained by the 
author in making a detailed map of the country about Portmadoc, 
Tremadoc, and Criccieth in Carnarvonshire, and describes the 
stratigraphy of the Cambrian and Ordovician rocks there exposed. 
The area described includes the original type-area of the Tremadoc 
Slates (Sedgwick & Salter), and the paper includes a detailed account 
of the local development of this well-known series. 

The first part of the paper is devoted to a brief summary of the 
results attained by former workers, and is arranged to show the 
various stages through which the nomenclature of the major sub- 
divisions of the Cambrian and Ordovician Systems have evolved. 

The sedimentary series are described in the order of their formation. 
The succession may be tabulated as follows :— 


Reports and Proceedings—Greological Society of London. 43 


Western or Criccieth District. Eastern or Tremadoe District. 

Rhyolitic ashes and agglomerates. 
Caraboc Variable dark - grey and _ black | Greyslate series, often strongly 
SERIES. shivery slates, banded, but with banded, with a few shelly 
no distinguishable horizons. fossils (Trinucleusand Orthis) 


in the upper part. 
Andesitic ashes and ashy shales. 
Dark banded slates with intense Vesicular andesites. 


cleavage ; no fossils found. Blue-black slates containing 
LLANDEILO graptolites. Zone of Nema- 
SERIES. graptus gracilis, 


Earthy slates, with occasional 
‘tuning-fork ’ graptolites. 
Shivery slates passing down into 


ARENIG Flaggy grits yielding Calymene 
Series. ) parvifrons. 
i Basal conglomeratic grit. Conglomeratic grit of Ynys 
Towyn. 
Unconformity. 
Garth Hill Beds: Not complete in the 
Grey-blue slates with Angelina. area studied. 


Penmorta Beds : 

Flagey mudstones and thinly-bedded slates, 

with Shwmnardia and the Shineton fauna. 
Portmadoce Beds : 

Thickly-bedded felspathic slates, with occa- 

sional Asaphellus. 
Moel-y-gest Beds : 

Banded grey slates and mudstones; few 

fossils, Acrotreta and Bellerophon. 
The Dictyonema Band: 

A constant and characteristic band of bright 
rusting blue-grey mudstones, with abundant 
Dictyonema sociale. 

Tynllan Beds: 

Thinly-bedded rusty shales with some hard 
grey mudstone bands, containing Viobe and 
Psilocephalus. (Symphysurus.) 

Sooty-black mudstones with Peltwrascarabeoides. 
Blue-black mudstone with Agnostus trisectus. 
Black slates, with calcareous bands often crowded 
with Orthis lenticularis. 
Dark flaggy slates with Parabolina spinulosa. 
, Grey-blue slates and flags crowded with Lingw- 
FFESTINIOG { lella davisii. 


TREMADOC 
SERIES. \ 


DoLGELiy { 
SERIES. 


—— 


SERIES. Grey flags and grauwacké with some coarser 
bands (1800 feet thick). 
Marntwroe ¢ Rusty grey and blue slates, with thin bands of 
Series. | felspathic grauwacke. 


The folding, the cleavage, the faulting, and the jointing of the rocks 
are described, and an attempt is made to show some relationship 
between the various stress-phenomena which have produced these 
structures. 

The great fault through Penmorfa is interpreted as a thrust-plane 
hading gently to the north-east. It is described as bounding two 
districts which are of a very different structural type, and is supposed 
to form the lowest sole of the group of thrust-planes which follow the 
southern margin of the Snowdonian mountain-tract. 


44 Reports and Proceedings—Geological Society of London. 


The well-known pisolitic iron ore of Tremadoc is shown to follow 
the line of this fault, and is thought by the author to be of the nature 
of a metasomatic veinstone. 

Direct evidence of overthrusting has been got from a study of the 
graptolite-bearing Llandeilo rocks of Tyddyn-dicwm, which have been 
exposed in two artificial trenches dug for the purpose; and the 
distribution of the andesitic volcanic. series in lines of detached 
lenticles among the Grey Slates is described as evidence of a similar 
reduplication of the newer series of the north - eastern district on 
a more extended scale. 

The actual lines of major thrust-planes, other than the Penmorfa 
Fault, have not been discovered; but, from the broad-spreading 
character of the sills of gabbroid dolerite, the author infers that these 
have come in along the thrust-planes. 

The petrogr aphical characters of these quartziferous and hypee iene 
bearing dolerites are not dealt with, but it is noted that the dolerites 
are (1) unaffected by cleavage and faulting; and (2) have meta- 
morphosed rocks which were already cleaved, “cut, and reduplicated by 
the thrust-faulting at the time of their intrusion: in this the author 
joins issue with previous observers in regard to their age. 

The Glacial and post-Glacial accumulations are also described in 


> outline. 


2. ‘On some Small Trilobites from the Cambrian Rocks of Comley 
(Shropshire).” By Edgar Sterling Cobbold, F.G.S. 

The majority of the trilobites noticed in this communication were 
obtained during the progress of some of the excavations referred to in 
the Report of the Geological Excavations Committee of the British 
Association, read at the Dublin Meeting, 1908. 

The specimens were derived from the Olenellus Limestone of Comley, 
and from the Grey Limestones which intervene between that horizon 
and the Conglomeratic Grit yielding a Paradoxides fauna. 

The author notices the occurrence of Microdiscus lobatus, Hall, 
M. speciosus, Ford, WU. helena, Walcott, and Ptychoparia (?) attle- 
boroughensis, 8. & F. He describes eleven species, apparently new, 
which he refers to the genera Itcrodiscus, Ptychoparia, Micmacca (?), 
Agraulos (Strenuella), “Anomocare (three species), Protolenus (two 
species), and two species to a new genus, to which Mr. Matthew’s 
species Micmacca (?) plana may also be referred. 

All the trilobites are represented by detached portions or fragments, 
often mixed indiscriminately, two or three species together, in the 
separate bands of rock; and the author adduces in some detail the 
evidence for correlating certain free cheeks, thoracic segments, and 
pygidia with the various head-shields, so that future workers may 
clearly distinguish between that which is actual fact and that which 
is a matter of inference. 


3. ‘The Rocks of Pulau Ubin and Pulau Nanas (Singapore).” By 
John Brooke Scrivenor, M.A., F.G.S. 
Pulau Ubin and Pulau Nanas are islands set in the eastern entrance 
to the Straits of Jahore, and consist of igneous rocks of considerable 
interest. Pulau Ubin is composed mainly of hornblende-granite, but 


Reports and Proceedings— Geological Society of London. 45 


a pyroxene-bearing microgranite is found also; while the hornblende- 
granite is cut by rhombic-pyroxene bearing veins and also contains 
angular masses of rock resembling the veins. 

The following grouping of the Pulau Ubin rocks (with which is 
included a rock found in the granite of Changi) is adopted. 


Normal hornblende-granite with a little monoclinic pyroxene. 
TOT 
Pyroxene-microgranite with dark masses resembling ITI (i). 
III. 
(i) Porphyry, with peculiar spongy masses of hornblende. 
(ii) Masses of a rock at Changi having the mineral constitution of an amphibole- 
vogesite. 
Vi 
(i) Ves of quartz-norite in the normal granite. 
(ii) Veins and masses of enstatite-spessartite in the normal granite. 
(ui) Masses of quartz-biotite-gabbro in the normal granite. 


Pulau Nanas consists of dacite-tuffs and dacite which are referred 
to the Pahang Volcanic Series, of Carboniferous or Permo-Carboniferous 
age. The tuffs and lavas have been altered by the adjacent granite of 
Pulau Ubin, and contain much secondary biotite and hornblende. 
They also contain some fragments that appeared to be altered chert, 
but their most remarkable feature is the presence of fragments of 
altered granite. 

The author discusses the mutual relations of the different rocks, 
and arrives at the following conclusions :— 

(1) The normal granite of Pulau Ubin is hornblende-granite, the 
age of which is certainly post-Triassic and pre-Eocene, perhaps post- 
Inferior Oolite and pre-Cretaceous. 

(2) Veins of quartz-norite and masses of quartz-biotite-gabbro, and 
veins and masses of a fine-grained rock which may be described as 
enstatite-spessartite, are found in the normal granite of Pulau Ubin. 
These point to an early differentiation of a granite and a gabbroid 
magma, perhaps in pre-Cretaceous times, and they are referable to 
rocks in Borneo and Amboyna. 

(3) A pyroxene microgranite and porphyry on Pulau Ubin, and 
a rock at Changi, having the mineral constitution of an amphibole- 
vogesite, are described. Their relations to the other rocks are not clear. 

(4) The dacite-tuffs of Pulau Nanas contain fragments of granite 
which must be of pre-Carboniferous age, and are referable to the 
granite of Amboyna. 

(5) The fragments of granite, and perhaps certain pebbles of schorl- 
rock, are the only evidence found as yet in the Malay Peninsula of 
pre-Carboniferous rocks. 

4. ‘The Tourmaline-Corundum Rocks of Kinta (Federated Malay 
States).” By John Brooke Scrivenor, M.A., F.G.S. 

Overlying the limestone on the west side of the Kinta Valley is 
a thin cap of schists, with which are found certain rocks the two 
chief constituents of which are tourmaline and corundum. They are 
often carbonaceous; and, in the many variations found, white mica, 
brown mica, pleonaste, rutile, and metallic sulphides occur. 

The tourmaline-corundum rocks contain certain structures which 


46 Obituary— Hilary Bauerman. 


are described in detail. These consist of round and oval cavities and 
bodies, the largest of which are about 6 millimetres in greatest width. 
Nothing can be proved regarding their origin, but the description of 
the rocks is summarized and a hypothesis adopted regarding their 
history, as follows :— 

(1) The tourmaline-corundum rocks of Kinta consist of varying 
amounts of tourmaline, corundum, carbon, white mica, spinel, and 
other minerals. 

(2) They contain cavities about 6 millimetres in greatest width, 
generally bordered by a layer of corundum grains, with tourmaline 
grains on the inside of this border. Sometimes solid bodies similar 
in size and shape to the cavities occur. They are composed of tour- 
maline and corundum, the former mineral, generally speaking, being 
more abundant towards the centre. Such bodies also show concentric 
structure. 

(3) Smaller bodies occur, sometimes, but not always, accompanied 
by the larger cavities and bodies. They consist of tourmaline, of 
corundum, and of tourmaline and corundum. When both minerals are 
present, the corundum forms a shell to a nucleus of tourmaline. The 
corundum bodies frequently show concentric structure. 

(4) The tourmaline-corundum rocks are associated with other rocks, 
which lead to the conclusion that the structures described in (2) and 
(3) are the result of replacement of the materials of pre-existing 
bodies at the time of extensive granitic intrusions. 

(5) They also are associated with rocks which point to the original 
beds having been laid down under conditions similar to those that 
obtained when the Pahang Chert Series was deposited. 

(6) As tourmaline-bearing partings in the limestone at Changkat 
Pari constitute a case of selective metamorphism, so it is thought that 
the tourmaline-corundum rocks as a whole mark a process of selective 
and intense metamorphism in beds associated with schists overlying 
the Kinta Limestone. 

(7) These beds were probably chert and silicified limestone, both 
being in many cases carbonaceous. 

8) The larger cavities and bodies mentioned in (2) are believed to 
be the result of replacement or partial replacement of oolitic grains. 

(9) The smaller bodies may be, in part, the result of replacement 
of the materials forming casts of radiolarian structures; in part, the 
result of the further development or replacement of spots seen in soft 
partings in the limestone at Changkat Pari; and in part, the result 
of the replacement of small oolitic ‘grains. 


OS Peer ASueye 


—. 


HILARY BAUERMAN, 
Assoc. M. Inst.C.E., Assoc. R.S.M., F.G.S. 
Born 1833. Diep DrcempBerr 5, 1909. 
Tux closing days of the old year have gathered in another prominent 


geologist and fellow-worker to his well- earned rest, leaving our science 
the poorer, and ourselves to regret his loss. Of Hilary Bauerman’s 


Obituary— Hilary Bauerman. 47 


early days we are not informed, but in 1851, at the age of 18, he 
became a student at ‘“‘the Government School of Mines and of Science 
applied to the Arts”, Jermyn Street, where he had the advantage of 
studying under Playfair, Ramsay, Forbes, Warington Smyth, Hunt, 
and Percy. It was specially due to the personal influence exercised 
by Dr. Percy and Sir Warington Smyth over the early students of the 
school that so many high classmen, like Bauerman, the Blanfords, 
F. Drew, Tookey, Sir C. Le Neve Foster, and many others, went 
forth to achieve high geological distinction in the world. From 
Jermyn Street Bauerman proceeded, in 1853, to the Freiberg Mining 
Academy, whence, after three years further study, he returned to 
England, and in 1856 accepted the post of an Assistant Geologist 
on the Geological Survey of Great Britain. But after three years 
work at home he was selected as geologist to the North American 
Boundary Commission, and during nearly six years he was occupied in 
most arduous survey work in Canada and the United States, including 
the delimitation of the Hudson Bay territory. Between 1863 and 
1888 he was busily engaged in Government and .professional work, 
mining and metallurgical surveys, and explorations abroad in almost 
every part of the world, save Australia and New Zealand. In 1883 
he was appointed lecturer on metallurgy at Firth College, Sheffield, 
and still earlier (1874-9) was joint examiner in mining and mineralogy 
for the Science and Art Department. 

His last official appointment (in 1886) was that of Professor of 
Metallurgy to the Ordnance College, Woolwich, from which he only 
retired in 1906, after some twenty years service. As a teacher, 
Professor Bauerman was particularly successful both with the cadets 
at Woolwich, who admired and revered him, and with the practical 
miners and metallurgists, including his workmen-students at the 
Firth College, Sheffield, and elsewhere, many of whom afterwards 
became his personal friends. 

In addition to important papers read before learned and technical 
societies Professor Bauerman was the author of textbooks on Descriptive 
Mineralogy and on Systematic Mineralogy. But his name is best known 
perhaps in connexion with his classical work on the Metallurgy of Iron, 
and with the treatise on Metallurgy by Phillips & Bauerman. He was 
for many years a valued contributor to the columns of the Hngineer, 
the ining Journal, and other papers. 

His extensive knowledge of chemical, mineralogical, and metal- 
lurgical subjects, and his experience as a teacher, led to his selection 
for the office of examiner for many years to the Civil Service 
Commissioners for the appointment of Mine Inspectors, to the 
Science and Art Department and the Board of Education in mining 
and metallurgy, and for a time in mineralogy also. He was likewise 
examiner of mining students to the Royal School of Mines and the 
Camborne School of Mines. 

Few of the congresses at home or abroad passed without his 
presence. He was a member of the Metallurgical Committee of the 
Seventh International Congress of Applied Chemistry held in London 
this year, and president of a section of the Sixth Congress held in 
Rome, 1906; and most of our International Exhibitions had the benefit 


48 Miscellaneous. 


of his experience as counsellor or juryman, from the Great Exhibition, 
in 1851 to the Franco-British in 1908, on whose metallurgical section 
he wrote two excellent monographs, published by the Iron and Steel 
Institute. 

Mr. Bauerman was elected a Fellow in 1863, and for nearly twenty 
years served on the Council of the Geological Society (from 1874 to 
1898); he also filled the office of Vice-President. He was a most 
valuable referee on all scientific papers, and, like the late Professor 
Morris, his knowledge was encyclopzdic both of men and subjects. 

Bauerman’s information was by no means confined to his own 
particular subjects, but extended over many sciences and arts. His 
interest in crystallography became an absorbing pursuit; and he found 
no greater delight than, with no appliances beyond an old envelope, 
picked out of the waste-paper basket, he would simply by deft folding, 
accompanied always by constant puffing and blowing, and many 
a joyful chuckle, develop some extraordinary figure in solid geometry. 

Professor Bauerman was a member of many scientific societies both 
at home and abroad. He was elected an honorary member of the 
Chemical, the Metallurgical, the Institute of Mining and Metallurgy, 
and the Iron and Steel Institute. He was an associate member of the 
Institution of Civil Engineers, as an F.G.S. he for many years filled 
the office of Treasurer to the Geological Club, and was an associate of 
the Royal School of Mines. He received the Howard Prize from the 
Institution of Civil Engineers in 1897, and in 1906 was awarded the 
gold medal of the Institute of Mining and Metallurgy. 

He was a perfect master of three languages, and being of an 
amiable disposition he always proved a most agreeable and interesting 
travelling companion, full of keen humour and geniality, so that 
throughout his life he attracted a large circle of warmly attached and 
admiring friends. 

Professor Bauerman had been seriously ill for about ten weeks, but 
the immediate cause of his death, which took place peacefully on the 
morning of December 5, was heart failure. (See notices in the 
Engineer, the Mining Journal, Iron and Steel Institute, and Nature.) 


MISCHLILUAN HOUS. 


Mr. O. T. Jonus, M.A., B.Sc., of the Geological Survey of England 
and Wales, has been appointed Lecturer in Geology and Physical 
Geography in University College, Aberystwyth. 

Mr. H. J. Seymour, B.A., of the Geological Survey of Ireland, has 
been appointed Professor of Geology in University College, Dublin. 

Museum Dxsrroyep By Fire.—The public library and museum at 
Kilmarnock has been destroyed by fire. The building, known as the 
Dick Institute, was presented to the town by the late Mr. James Dick, 
of Glasgow, about nine years ago. The museum contained the 
geological collection of the late Mr. James Thompson, F.G.S., the 
destruction of which is much to be deplored.—Zimes (weekly ed.), 
December 3, 1909. 


len ‘Decade Vo Vor VII.—No. II._. Price 2s. net. 


THE 


| GROLOGICAL MAGAZINE 


OR 


Monthly Journal of Geology. 


WITH WHICH IS INCORPORATED 
THE GHOLOGIST. 


EDITED BY 


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ASSISTED BY 
Proressor J. W. GREGORY, D.Sc., F.R.S., F.G.S. 
Dr. GEORGE J. HINDE, F.R.S., F,G.S, 
Sm THOMAS H. HOLLAND, K.C.IE., A.R.C.S., D.Sc., F.B.S., F.G.S. 
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; HORACE B. WOODWARD, F.R.S., F.G.S. 


FEBRUARY, 1910. 


CONTENTS. 


I. Ontetnan ArvictEs. ~ Page Reviews (continued). Page 
Sculpturings of Chalk Downs in Geology of Bodmin and St. Austell. 
Kent, Surrey, and Sussex. By By W. A. E. Ussher, etc. ... .... 84 
GuorGe Cuincn, F.G.S8. (Plate VI Geetian South Polar Expedition She ue 
and two Text-figures.) ... ... ... 49 Eistesser eae s Aids to Geology ...~ 88 
es : < eology of New Zealand . 88 
ee ee cae oe BY Phillips River Goldfield, W. Australia 89 
Collece, Cambridge. (Plate VII Ravines of the Tschokusu Plateau ... 89 
AEN eet naates) oe 53 | Pocket-Guide to Chalk Fossils... ... 90 
= ie Ore Deposits of South Africa ... ... 90° 
Faunal Succession of Carboniferous Brief Notices: Pleistocene Geology 
Limestone, Llantrisant. By G. - (Chicago) — Philippine Islan Js — 
Detérme, Professor of Geology, e: Canadian Geology —The Mining 
Tile. (With a Text-map.) .. 67 | Magazine—Bristol_Geoloey—New 
Origin of the Nile Valley and the Jersey Geology— Geological Litera- 
Gulf of Suez. By JOUN Batu, ture.. a BGA Ncke wee he eee ISO 
nse D).Sce.,.F.G.S.... ..6 26 71 


New Chalk Polyzoa. By R. M. IV. Reports AnD PRocEEDINGS. 
Bryponz, F.G.S. (Plate VIII.) 76 | Geological Society of London— 


; 2 

Discovery of Archcosigillaria in December aed ee ae 2, Ca 
Westmorland. Eye: Ww. neh < Camensies ee 

“CoS is Bernard Hobson Fe as a cea eueR Ee OD. 


II. Novices or Memorrs. 


Spontaneous Luminosity of Uranium. : a MISCELLANEOUS. 
By Hon. R. J. Strutt, M.A.,F.R.S. 81 | Geological Society Medals and Awards 


» for February, 1910 erase 5-96 
III. Reviews. . Dr. W. F. Hume, Dire ofthe 
Geology of Basingstoke. By SIE O: Geological Survey nego hi: an bi HS! 96 
White... i5 beeen tole. WV Mrraten. | ose “96 He 


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Kes The Volume for 1909 of the GEOLOGICAL MA AZINE is neaily, 
price 20s. net. Cloth Cases for Binding may be had, p 


A COMPLETE REPRODUCTION OF THE SKELETON OF 
DINORNIS MAXIMUS 


(the gigantic ‘ Moa’ of New Zealand) as supplied to the Natural History Museum, 
Brussels, by 


ROBERT F. DAMON, Weymouth, England. 


Height 300 cm. 


rd 


yy 
AL 


2 


Grou. Mac. 1910. ; Puate VI. 


Tre SCULPTURINGS OF THE CHALK Dow Ns. 


Fic. 1. Simple coombes near Ditchling Beacon, Sussex. 
Fic. 2. The ‘Seven Sisters’, between Cuckmere Haven and Birling Gap, Sussex. 


“a 


THE 


GEOLOGICAL MAGAZINE. 


NEW SE RIESs DECADE Vi VOR Vil: 


No. II.— FEBRUARY, 1910. 


@RPtG aN VATE), “ASkvl teGria aS: 


od 


J.—Tue Scurrrurrnnes or tHe CHatk Downs or Kent, Surrey, 
anv Sussex.' By Groren Crinen, F.G.8., F.S.A. Scot. 


(PLATE VI.) 


fY\HE aim of this paper is to offer an explanation of the phenomena 
intimately related to the sculpturings of the Chalk Downs ‘in the 
district under review, namely :— 
(1) The Dry Chalk Valleys. . 
(2) The River System of the Wealden area, as far as it relates to 
the Chalk Downs. 
(3) Incidentally, the Denudation of the Wealden area. 
The various sculpturings of the Chalk Downs fall naturally into 
two main groups, viz. :— 
(1) Dry Valleys, comprisinge— 
(2) Simple coombes, or short valleys, without tributary valleys, and 
(4) Complicated, sinuous valleys, usually extending for some miles, and 
with numerous tributary valleys. 
(2) Wet Valleys, cut through the North and South Downs, in which flow rivers 
which drain the Wealden area. 

The chief characteristics of the Dry Valleys (1) are steep, sloping 
sides, rounded outlines, absence of terraces, general absence of deposits 
of flints, etc., and proportionately large area of valley as compared 
with unsculptured areas. 

The simple coombes or short valleys (@) are found usually on the 
Chalk escarpment opposite the Weald, and are remarkable for their 
steepness, both of sides and the general fall of the level of their 
deepest parts. (See Pl. VI, Fig. 1.) 

The complicated, sinuous valleys (6) are found usually on the 
northern slope of the North Downs and the southern slope of the 
South Downs. The number of tributaries and the breadth of 
the valleys are two remarkable features to which no one yet seems 
to have drawn particular attention. They are points which certainly 
do not appear to have been sufficiently explained by the theories 
hitherto advanced by geologists. If at first they seem to present 
‘difficulties, these very difficulties are of the greatest value as indicating 


1 This paper is substantially the same as that communicated to the Geological 
‘Society of London, April 7, 1909, certain revisions having been made subsequently. 
A short abstract only was printed in the Q.J.G.S., vol. Ixv, pp. 208-9. 


DECADE V.—VOL. VII.—NO. II, 4 


50 George Clineh—Sculpturings of the Chalk Downs. 


the direction in which we may look for an explanation of the whole 
story of the origin and development of the valleys of the Chalk Downs. 

Excellent examples of valleys of this type are to be found in 
abundance in the North and South Downs, in the former especially to 
the south of Croydon, in West Kent, and throughout the eastern 
portion of Surrey. (See Fig. 1.) 


CROYDON 


MERSTHAM 
Fie. 1. Diagram showing complicated and sinuous Dry Chalk Valleys of the 
North Downs between Merstham and Croydon, Surrey. 


The Wet Valleys (2) are characterized by the large size and breadth 
of their passages through the Downs, and by the extensive watersheds 
drained by the rivers which now occupy them. In general outline 
and character they are not unlike the Dry Valleys, but they are 
invariably cut to a lower level in the Chalk, and in all cases, I think, 
they contain deposits of river gravel. Generally speaking, however, 
they are of less complicated form than the Dry Valleys. The following 
rivers now occupy the Wet Valleys of the district with which the 
present paper is concerned: (orth Downs) Wey, Mole, Darent, — 
Medway, Stour; and (South Downs) Cuckmere, Ouse, Shoreham River 
or Adur, atid Arun. 


George Clineh—Sculpturings of the Chalk Downs, 51 


The neighbourhood of Beachy Head presents many interesting 
points which illustrate the sculpturing of the Chalk Downs. The 
Chalk here ends abruptly in a lofty cliff, which once extended much 
farther to the south. The western slopes of the Downs in this part 
of Sussex are somewhat precipitous and form part of the watershed of 
the River Cuckmere, an important watercourse whose most distant 
source may be traced to Heathfield Park. The river has several 
tributaries, and drains a large part of the Sussex Weald. Its former 
importance is indicated much more vividly by the valley through 
which it flows than by the present volume of its waters. 

Between Cuckmere Haven and Birling Gap the sea-coast presents 
a remarkable series of gable-like cliffs, known, from the number of its 
eminences, as the Seven Sisters (see Pl. VI, Fig.2). These elevated 
points of Downland are divided by eight valleys leading in a practically 
north and south direction, but six of them are short and of simple 
form, dying out about a mile to the north of the sea-coast. The 
others are of more complicated form. It is clear that they all form 
parts of a complete system of branching valleys, which formerly 
drained the district. All the southern part has been eroded by the 
sea, and what may be called the midrib of the series was situated 


Fic. 2. Diagram showing the Dry ¢ Chalk Valleys of the ‘ Seven Sisters ’, and 
a suggested restoration of the valley system in the neighbourhood. 
perhaps within 2 miles of the present coastline (see Fig. 2). The 
destruction of this series of dry valleys was probably due partly 
to marine erosion and partly to the forces which excavated the valley 
through which the Cuckmere Rivernow flows. The nature of those 
forces will be considered at a later stage in the paper.’ 


1 See a paper ‘‘On the Geology of the Neighbourhood of Seaford ’’, by J.V. Elsden: 
Q.J.G.S., vol. Ixy, pp. 442-61. 


52 George Clinch—Seulpturings of the Chalk Downs. 


Derosirs 1n THE Dry Vatteys. 

Generally speaking the Dry Chalk Valleys do not contain any 
considerable amount of deposits of hard and insoluble matter. Many 
are indeed quite free from such accumulations ; but some are partially 
occupied by beds of re-arranged Chalk; chalky matter interspersed 
with sand from the Wealden beds; flints, worn and unworn; 
ferruginous sandstone from the Lower Greensand; and masses of 
Sarsen Stone. 

An important and significant deposit occupies the bottom of the 
valley at Purley, near Croydon, a valley which, although now dry, 
once formed the upper part of the Wandle Valley (Fig. 1) when that 
river drained part of the Weald. It contains blocks of Sarsen Stone 
of large size, weighing about a ton, large blocks of equal weight of 
pebbly conglomerate, and numerous subangular flints as well as 
Tertiary pebbles. A good section of this was exposed when the 
waterworks at Purley were constructed. Sarsen blocks of smaller 
size, and chalky material and flints occur in the Coombe Rock at » 
Black Rock near Brighton. 

Denvuparion or THE WHALD. 

The relation of Chalk sculpturings to the denudation of the Weald 
was probably intimate. Strictly considered, it is clear that the very 
sculpturings with which this paper deals are but part of the process 
of the uncovering of the Wealden strata, by the erosion of the Chalk 
and other superincumbent deposits. Nevertheless the paucity of 
remains of the harder and more insoluble parts of the Chalk in the 
Wealden area is well known, and this circumstance has given rise to 
an extraordinary variation of opinions amongst geologists as to the 
force or forces which have removed the Chalk. ‘The elevation of the 
centre of the Weald is another important point, and unquestionably 
it has had much to do with this denudation. How far the actual 
upheaval may have broken up the Chalk cannot now be estimated 
with precision. ‘There can be no doubt that there was much disloca- 
tion and disruption, although the views expressed by some writers? 
on the subject seem to be extravagant. 

The Wet Valleys which cut through the Downs are probably the 
channels by which the eroding and transporting forces conveyed the 
material to other areas outside the Weald. What those forces in all 
probability were is a question upon which I shall have occasion to 
touch when dealing with the origin of the dry valleys; but, I may 
add, I do not for a moment suggest that anything of the nature of 
glaciers was the transporting force. 

Retation or Dry Caark Vatieys ro Cray-wira-Fiits. 

The origin of Clay-with-flints on the higher Chalk has long been 

a disputed point. Geologists are by no means agreed as to whether 


1 In Scepticism in Geology (pp. 44-5), William Longman suggested that ‘‘ the 
Chalk escarpments may have been parted asunder like the sinews of a shoulder of 
mutton on the application of a knife’? ; and Sir Henry Howorth in Ice or Water, 
vol. i, p. 525, holds that the Chalk beds were dragged apart over the softer under- 
lying strata for a distance of 25 miles. To my mind such an extended movement of 
the Chalk seems unlikely. 


George Clinch—Sculpturings of the Chalk Downs. 53 


it is a mechanical or a chemical deposit; but, I think, the study of its 
phenomena in connexion with the dry valleys of the Chalk tends to 
show that it was due to mechanical rather than chemical agencies. 
It lies mainly on the table-lands of the Chalk, and is rarely found in 
the valleys except in a re-arranged condition or as rainwash. 

The extreme probability that its material was derived in the first 
instance from the dissolution of the Chalk does not, I submit, militate 
against the possibility of its subsequent re-arrangement by mechanical 
agencies. 

The presence of clay-with-flints on the Chalk plateau and its 
absence from the valleys are points well shown in Kent. A good 
example to the east of the River Darent has been figured in one of the 
admirable papers of the late Sir Joseph Prestwich.* 


River Systems. 


It will not be necessary, for the present purpose, to go deeply or 
fully into the river system of the Weald; but the fact that many of 
them flow through channels which cut transversely through the Chalk 
Downs, both north and south, is important as pointing to a very early 
system of watercourses which drained not only the Wealden area as 
we know it, but the Wealden dome before it was bereft of its Chalk 
and Tertiary beds. 

The valleys of the Wye, the Mole, the Medway, the Cuckmere, the 
Ouse, the Shoreham River (now called the Adur), and the Arun are 
broad and important. The Darent Valley is less marked. That of 
the Wandle is well-defined, but dry in its upper part, having had its 
catchment area cut off by the rapid development of the Gault valley. 
The old valley of the Ravensbourne, the main part of which is now 
dry, goes quite as far south as the Chalk escarpment, and probably once 
drained a small part of the Wealden dome. The chief point of interest 
of all these valleys is that they run transversely to the lines of the 
Chalk ridges, and point to an ancient drainage system. 

The fact that the gravels in these valleys contain materials brought 
from the Wealden side of the Chalk escarpment is another of the 
interesting points in their geological history. 


THEORIES ON THE DENUDATION OF THE WEALD AND THE FoRMATION 
oF VALLEYS. 


The papers ‘‘ On the Anticlinal Line of the London and Hampshire 
Basins”, by Peter John Martin, F.G.S., are of great value. They 
are, in fact, a storehouse of information to which Lyell and many 
subsequent writers have turned for inspiration and facts. Martin’s 
papers were published in the Philosophical Magazine in 1851, 1854, 
and 1857, but they deal with observations made as early as 1828. 
After discussing the various phenomena of the Weald, he writes :— 


Ba To conclude: the obvious inferences to be drawn from what we have seen are 
these :— 

“* Since the deposition of the tertiary beds a great and sudden upheaval of some 
parts, and perhaps contemporaneous subsidence of others, took place over a widely 
extended area ; perhaps over the greater part of the South of England. 


1 Q.J.G.S., vol. xlvii, pl. vii. See also Jukes-Browne, ibid., vol. Ixii, p. 132. 


4 


54 George Clinch—Sculpturings of the Chalk Downs. 


‘* That the phenomena of the arrangement of valleys, and of watersheds, over all 
the length and breadth of the anticlinal line of the London and Hampshire basins, 
respond to this covvulsion. 

“¢ That this convulsion was attended or immediately followed by a devastating flood, 
which excavated and carried off the broken materials, and only left a small quantity 
of drift to attest its agency ; and that this inundation subsiding, the waters withdrew 
at once, a period of tranquillity succeeding, which has continued up to the 
present time.’’ 


Mr. Clement Reid’s paper,! ‘‘On the Origin of Dry Chalk Valleys 
and of Coombe Rock,” was published twenty-two years ago, and 
I think all geologists will admit the value of his contribution to the 
subject of Chalk hill-sculpture. 

Mr. Reid commenced his paper by pointing out the intimate relation 
of Dry Chalk Valleys and Coombe Rock, a position which I suppose 
no one would now wish to challenge. After a description of the sea- 
ward side of the South Downs, and of the general features of Dry 
Chalk Valleys, the author proceeded to discuss the various theories 
advanced by geologists to account for the erosion of the Dry Valleys. 
He cited three theories, viz. :— 

(1) Former submergence, and consequent rise in the plane of saturation. 
(2) A former higher level in the plane of saturation before the valleys had been 


cut to their present depth. 
(8) An enormous increase in the rainfall. 


All these theories were dismissed as insufficient to account for the 
phenomena of the Dry Valleys, although their partial aid in producing 
them was accepted. Mr. Reid remarks: ‘If these valleys had been 
gradually cut back by streams, many of them ought to fall northward 
to the escarpment, where most of the large springs are found; but 
nearly all the Chalk Coombes follow the general slope of the ground 
and open to the south.” 

The most important part of Mr. Reid’s paper is that in which he 
deals with the question of the origin and method of erosion of the 
valleys. Judging from the flora and fauna, he assumes that the 
temperature of North-West Europe, at the period under review, was 
probably 30° lower than it is now. He writes :— 


‘«This would give a mean temperature in the South of England very considerably 
below the freezing-point; consequently all rocks not protected by snow would be 
permanently frozen to a depth of several hundred feet. ‘This would modify the entire 
system of drainage of the country in a way that I do not think has been realized. 
All rocks would be equally and entirely impervious to water, and all springs would 
fail. Whilst these conditions lasted any rain falling in the summer would be unable 
to penetrate more than a few inches. Instead of sinking into the Chalk, or other 
pervious rock, and being slowly given out in springs, the whole rainfall would 
immediately run off any steep slopes like those of the Downs, and form violent and 
transitory mountain-torrents. ‘These would tear up a layer of rubble previously 
loosened by the frost and unprotected by vegetation. The material carried away 
would not have the Chalk washed or dissolved out, for a single flood of this description 
could have little solvent power, and much of the Chalk might not be thoroughly 
thawed. 

«« Each of these floods would have an enormous scouring and transporting power ; 
for the fall in the valleys is very great. It is noticeable that no Coombe Rock is 
found in the valleys that have a greater slope than 100 feet to the mile, and that the - 
main mass is deposited south of the Downs where the slope is much less.”? 


1 Q.J.G.8., vol. xiii, pp. 364-758 


George Clinch—Sculpturings of the Chalk Downs. 55 


In the discussion to which Mr. Reid’s paper gave rise, the most 
remarkable view on the subject was expressed by Professor Seeley, 
who attributed the Dry Valleys mainly to marine erosion. He sug- 
gested, too, that the deposit of Clay-with-flints had been swept into 
its present position by ‘tidal waves’ at the time when the land was 
being submerged and the waters were working up the valleys. 

Sir A. Geikie remarked that the valleys were doubtless outlined | 
before the Chalk was exposed at the surface, and then subsequent 
erosion in the Chalk had been effected by solution and mechanical 
abrasion under conditions which have now disappeared. 

Topley referred the origin of Dry Chalk Valleys to the action of 

‘running water’ on land that was solidly frozen. 

It will be observed that several authorities were inclined to ascribe 
the origin of the valleys to the erosion of running water. Seeley’s 
theory as to marine action may be dismissed, perhaps, as lacking both 
proof and probability, but Topley’s sug gestions as to ‘ running water’, 
and Mr. Reid’s as to summer floods, are, I venture to think, scarcely 
less inapplicable. 

If water, even in the form of ‘mountain-torrents’, as Mr. Reid 
suggests, was the excavating force, we should expect to find (1) a 
sufficient watershed, (2) terraces on the sides of the valley repre- 
senting different stages in the volume and velocity of the torrent, and 
(3) a deposit of hard and insoluble matter, such as flints and other 
debris of the Chalk. The first and second of ‘these features ¢ are lacking, 
and the third is by no means constant. 

Since the publication of Mr. Reid’s paper geologists Nee suehi in 
other directions for explanations of the Dry Chalk Valley systems. 
One of the theories most in fashion in recent times is that known as 
the ‘solution’ theory, by which pluvial activity is invoked, and the 
whole of the phenomena of Chalk sen ippunines is by some! referred to 
the solvent influence of rain and atmosphere.’ 

The direction of the Dry Valleys, we are told, was ‘doterasined by 
the courses of streams and rivers on the surface of. the Chalk plateau 
in remote times. The effect was to remove the clay capping and thus 
lay bare the soluble Chalk to the influences of rain and atmosphere. 
Every part which was bereft of its clay protection became-in time, 
after a long series of years, hollowed out into valleys. 

I am bound to say that this theory, ingenious as it is, gives; to my 
mind, far too great importance to (1) the solubility of the Chalk, and 
(2) the influence of rainfall. Indeed, I think such a theory ‘is insuffi- 
cient to account for certain definite and fairly constant characteristics 
of these sculptured channels, the most important and obvious of which 
are (1) the sinuosities of the valleys, (2) their elaborate and compli- 
cated forms, (3) the general downward inclination of the valleys 
towards their outlets, and (4) the presence of rolled chalk, flints, etc., 
in the valleys themselves. 

That erosion rather than solution was the active foree in the 
formation of some of the dry chalk valleys is shown ‘by deposits 
of high-level gravels having been cut through. Now, it is obvious 


1 See G. W. Young, Proc. Geol. Assoc., 1905, vol. xix, p. 191. 


56 George Clinch—Sculpturings of the Chalk Downs. 


that if the valley were due to solution the gravel would have been let 
down with the lowering surface of the chalk, but the fact that it has 
been entirely swept out of the valley affords clear proof of erosion. 
There is abundant evidence of this, but for the present purpose it will 
suffice if reference is made to the excellent example in the Seaford 
district to which Mr. J. V. Elsden has recently drawn attention in 
his paper,' already mentioned, on the geology of that neighbourhood. 

That.a certain amount of sculpturing of the Chalk may be attributed 
to solution, either pluvial, or atmospheric, or both, particularly in 
association with joints or faults, is well known and indisputable. An 
excellent example may be seen at Box Hill, near Dorking, in Surrey, 
and there are many others. But in these the bottom of the depression 
is not regularly inclined downwards, like those of the typical Dry 
Valleys. 

Moreover, the solution theory leaves us much in want of some 
reasonable controlling force which, in the initial and early stages, 
would give form to the complete and elaborate valley system. If the 
solution theory were accepted we should expect deep ravines in the 
Chalk, following precisely or nearly the direction of the original stream 
or river which removed the clay capping. A certain broadening 
would doubtless follow in the course of time, but we should not expect 
such elaboration and development as we actually find. The erosion 
would be in the direction of depth rather than breadth, because the 
degraded clay on the sides of the valleys would still continue, to some 
extent, to protect the Chalk from rainfall and consequent solution. 
In a word, the solution theory involves vertical rather than lateral 
development, yet lateral development is one of the most noteworthy 
characteristics of the valleys. 

Another weak point, among many, about the solution theory is that 
it fails to account for Dry Valleys on the Chalk escarpment, where 
there is no controlling and protecting clay covering. 

Finally, { submit, the solution theory is effectually disproved by 
the rolled material in the valleys. 

Mr. Reid’s suggestion that upon the approach of mild temperature 
floods like mountain-torrents swept the loosened material out of the 
Chalk valleys, makes no sufficient allowance, I think, for the vast 
masses of ice which, wholly or in part, must have occupied the valleys. 
The presence of these ice-masses must haye tended to lateral erosion 
and consequent widening of the valleys. 

The porous nature of Chalk is a point with which Mr. Reid deals 
thoroughly, and I think his theory that the bed was rendered im- 
pervious by means of frost is one which has generally been accepted 
by geologists. But I do not think it at all likely that the frost 
extended downwards into the earth for some hundreds of feet, because 
there would doubtless be a protecting covering of snow. ‘Ten or 
twenty feet would be ample to render the Chalk impervious, and 
I cannot find evidence of frost at a greater depth. 

Those who have hitherto attempted to explain the denudation of the 
Weald and the formation of the Dry and Wet Valleys of the Chalk 


1 Q.J.G.5., vol. Ixv, pp. 442-61. 


George Clinch—Sculpturings of the Chalk Downs. DT 


Downs as due to the erosive action of water, have not, I think, given 
sufficient importance to the fact that Chall, of all rocks, is peculiarly 
_ sensitive to the disintegrating influence of frost, particularly when 
the beds are heavily charged with water. The effects of a frost may 
be seen, when thaw sets in, in every chalk-cutting and chalk-pit. 
What its effects may have been when these valleys were half-filled 
with water and the temperature fell very low, it is difficult to realize 
at the present time; but the work that was accomplished by alternate 
freezing and thawing is to be seen in the valleys of the Chalk Downs, 
many of which are eaten back by the disintegrating and disrupting 
frost into intricate and complicated forms. In some cases this erosion 
has been carried to the extent of breaking down the divisions between 
adjacent valleys, and the formation of isolated hills, (See Fig. 1.) 

The suggestion I make, then, is that the chief eroding agent was, 
not the waves and tides of the sea as some have suggested, nor the 
‘running water’, nor the ‘mountain-torrents’ of others, but the 
frost itself acting upon Chalk charged or saturated with water.' 

By this means, I suggest, the valleys were cut back into the Chalk 
Downs, the development being to a large extent lateral. The frost 
was most active, I suggest, where the Chalk was wettest, and the 
waters standing in the valleys half-choked with ice provided precisely 
the necessary condition to produce the maximum breaking-up of the 
Chalk. 

I have spoken of the relatively small size of the catchment-area as 
compared with that of the valleys. It had, to me, long been an 
enigma; but with the explanation I offer, I think, the difficulty 
disappears, because the eroding forces were contained in the valleys 
themselves when the Chalk below was impervious and they were 
partly filled with water. The wet condition of the Chalk may have 
arisen from partial thaw and not wholly from rainfall. 

At the same time it must be borne in mind that the condition of 
semi-saturation, under which the frosts were most destructive to the 
Chalk, was most naturally produced when there was some kind of 
catchment basin. Indeed, it would seem that such a basin was 
absolutely necessary to produce the requisite conditions, because 
when the valley was cut back quite near the edge of the Chalk 
escarpment, and the drainage became insignificant, the hollow channel 
dies out. 

The transporting agencies of floating ice, and the floods arising from 
the periodical breaking-up of the ice-masses in the valleys would 
doubtless be sufficient, in the case of the steeper valleys or coombes, 
to sweep the debris down into the sea or into the valley or estuary of 
the Thames. 

The whole of the phenomena of the Dry Chalk Valleys and other 
forms of sculpturings of the Chalk Downs may, I submit, be amply 
accounted for by the forces I have attempted to describe; and if, as 
seems obvious, the valleys be closely related to the denudation of the 
Weald, it is perhaps within the region of probability that the latter 
may have been influenced by the same cause. 


1 On this subject see remarks by S. V. Wood, jun., Q.J.G.8., vol. xxxvili, p. 718. 


58 D. G. Lillie—Fossil Flora, Bristol Coal-field. 


EXPLANATION OF PLATE VI. 


Fie. 1. This photograph of the northern escarpment of the South Downs near 
Ditchling Beacon affords an admirable illustration of the simple steep - 
coombes to which reference is made in the paper. Ditchling Beacon is 
shown on the high point about the middle of the view. At the foot of 
the steep escarpment is shown the ancient hedge which separates the 
down land trom the arable land of the Weald. The latter in prehistoric 
and early historic times was largely forest land. 

., 2. The Seven Sisters, a series of alternate valleys and lofty cliffs, owe their 
shapes to a former system of branching dry valleys, much of which has 
been destroyed, probably by marine erosion. 


IJ.—Nores on rue Fosstr Frora oF tur Brisrot CoaL-FIEerD. 
By D. G. Lrizin, B.A., St. John’s College, Cambridge. 
(Rl ACRE AVele) 
ORE than twenty-three years have now passed since Dr. Kidston 
published his memoir on the fossil flora of the Somerset and 
Bristol Coal-field, and in the meanwhile no further additions .to our 
knowledge have been made. Kaidston’s paper was chiefly concerned 
with the plant-remains of the southern or Radstock portion of the 
basin. ‘lhose from the northern or Bristol area have only been studied 
incidentally. This would seem quite natural on account of the greater 
size and industrial importance of the Radstock Coal Series, and from 
the fact that this locality has been long known to yield the finest and 
best preserved impressions of fossil plants to be found in any coal-field 
in the British Isles. The collieries in the Bristol district are com- 
paratively few and smaller, fossil plants being much scarcer and less 
well preserved. 

In view of the fact that the Bristol area is becoming less extensively 
worked every year, it has seemed to me worth while to collect as 
many plants as possible from this district, in the hope of adding to 
those already recorded. It also has been desired to obtain a flora 
sufficiently characteristic to mmdicate the paleobotanical horizon as 
compared with those of the Radstock district and other coal-fields. At 
present the evidence rests entirely on stratigraphical data. With this 
end in view, I spent some weeks, during the last two summers, in 
collecting fossil plants from the waste-heaps of the seven collieries 
which alone appeared to be still working in the Bristol district. 

In recent times several collieries have been completely abandoned, 
including all those on the Nailsea basin, and the possibility of obtaining 
plant-remains from this coal-field is becoming less every year. The 
spoil-heaps of four of the collieries now working proved to be almost 
completely barren on both occasions when [ visited them, the shale 
being much slickensided and all organic remains obliterated. Thus 
there remained only three collieries from which plants can be collected, 
und one of these is exceedingly small. A week’s work was con- 
sequently sufficient each year to practically exhaust the spoil-heaps. 

The physical features and stratigraphy of the Bristol district 
have been described by several writers! in tke past. In more recent 


1 See Kidston, Trans. Roy. Soc. Edinb., vol. xxxiii, pt. ii, p. 338 note. 


D. G. Lillie—Fossil Flora, Bristol Coal-field. 59 


years, important and able papers by Mr. James McMurtrie, F.G.8.,} 
and Mr. H. Bolton, F.G.S.,? have been added to this lst. It will 
only be necessary to very briefly recapitulate the main characters of 
the area for the purposes of the present paper. 

The Coal-measures of the Somerset and Bristol basin consist of two 
productive divisions, separated by the Pennant Rock. The upper 
division, lying above the Pennant, is again divisible into a higher, 
the Radstock Series, and a lower, the Farrington Series, separated 
by barren beds known as the Red Shales. The lower division cam be 
also subdivided into the New Rock and Vobster Series, though the 
line of demarcation between them is less distinct. The succession of 
the Coal-measures in that part of the basin which intervenes between 
the Radstock district and the neighbourhood of Bristol is not known 
with certainty; but the main stratigraphical divisions of the latter 
appear to correspond with those at Radstock, though it has not been 
found possible to correlate the coal-seams of the two areas. Indeed, 
the correlation of many of the seams, even within the Bristol area 
itself, are either unknown or uncertain. 

The following table indicates a comparison of the series in the two 
districts, and includes the names of the collieries at present working 
in the Bristol area :— 


Rapstock AREA. COLLIERIES IN THE Briston AREA. 
Radstock Series 
Upper (about eight seams). Absent. 
Division ~ Red Shales. Very thin. 
(2200 feet) | Farrington Series Coal Pit Heath Colliery. 
(six or more seams). Working ( Parktield Colliery. 


same seams | Shortwood Colliery, 
Pennant Rock (3000 feet). 


New Rock Series Working ( Kingswood Collieries (Speed- 
Lower (eighteen or more thin same well Pit, Deep Pit), Haston 
Division - seams). seams \ Colliery. 
(2800 feet) | Vobster Series 
(eight or more seams). Hanham Colliery (?). 


We thus see that there are now only three collieries at work in the 
Farrington Series in the Bristol district. Each, however, is working 
several seams, and all three have yielded fossil plants; but the exact 
seam from which they came is unknown. Coal Pit Heath Colliery is 
probably working higher seams in the Farrington Series than Parkfield 
and Shortwood Collieries. Two collieries are working, three pits in 
all, in the New Rock Series, but only one specimen could be obtained 
from the heaps after repeated searching. The Hanham Colliery, 
which, it is believed, is working the Vobster Series, has also proved 
entirely barren as a collecting-ground. : 

Thus the impressions described here are all derived from the 
Farrington Series, and these may be compared with the flora of the 
same series in the Radstock area, already described by Kidston.’ 

So far we have been concerned only with the impressions, but some 


' McMurtrie, Trans. Inst. Mining Engineers, 1901, vol. xx. 
2 Bolton, Q.J.G.S., 1907, vol. Ixii, p. 445. ¥ 
3 Kidston, ‘Trans. Roy. Soc. Edinb., vol. xxxiii, pt. 1, p. £10. 


60 D. G. Lillie—Fossil Flora, Bristol Coal-field. 


interesting plant petrifactions have also been obtained, and we may 
commence with a brief notice of these. 


PETRIFACTIONS. 


In addition to impressions found in the shale bordering on the coal- 
scams, a limited amount of petrified material has also been obtained, 
which is of special interest, because our supply of structure material 
has hitherto been confined to one or two seams in the Lower Coal- 
measures of Yorkshire and Lancashire. This material was originally 
recognized by Mr. Bolton, F.G.S., Curator of the Bristol Museum, 
who drew my attention to it. It has only been obtained at one 
locality, Staple Hill, about 3 miles to the north-east of Bristol, on 
the north side of the Kingswood anticline. A sinking was made here 
a year or two ago, through the Pennant Grit, but was afterwards 
abandoned at a point rather beyond the base of the Pennant. At this 
level a peculiar breccia-conglomerate, containing numerous angular 
and rounded pebbles, set in a sandstone matrix, was met with in 
sinking the shaft. This rock will be more fully described by. 
Mr. Bolton. It is only necessary here to add that, in addition to the 
pebbles, this breccia contains numerous fragments of stems and petioles 
of plants in some of which the structure is preserved; the material 
being calcified. The amount of this conglomerate is very limited, 
and it is very doubtful whether any more can be obtained in the 
future. Many of the blocks thrown out from the shaft have become 
considerably weathered, and the plant petrifactions quite spoilt for 
purposes of section cutting. However, a number of sections have been 
cut of the petrified material, and several of these proved to be well- 
preserved stems or petioles. Twigs of Cordaites appear to be the 
commonest fossils, while in, addition a well-preserved petiole of 
Myeloxylon has been obtained. It is hoped that an opportunity will 
be found to describe these structure specimens before very long. At 
present we must content ourselves with a record of their discovery. 


IMPRESSIONS. 


We now pass to a record of the plant impressions obtained from the ° 
Farrington Series in the Bristol district. 

The following list of plants, recorded by Dr. Kidston in 1887, 
comprised the entire flora then known from the Farrington Series of 
this area, and no further additions have been made, as far as I am 
aware, up to the time of writing :— 


LocaLirigs. 
Sod | Coal Pit 3 | Puckle- 
Equrserates. | Heath. Parkfield.) church. 
Calamites ramosus (Artis). . . . . . . «| - x 
Annilaria stellata (Schloth.) . . . .. . - x 
SPHENOPHYLLALES. . 
Sphenophyilun emarginatum, Brongn. . . .« — x | = 
| | 
PreRIDOSPERMS AND FERNS. | | 
. rye | | 
Alethopteris lonchitica (Schloth.) . | x 
Neuropteris macrophylla, Brongn. ae Ki = 
BNEROUCE MELO TEMA TI |e): uue e tA IneY Deeee Pe gmk = x | = 
Pecopteris arborescens (Schloth.) . . . . . = x | a6 


D. G. Lillie—Fossil Flora, 


PTERIDOSPERMS AND FERNS (continued). 


Pecopteris oreopteridia (Schloth ) . 
P. pteroides, Brongn. ; 
Rhacophylium crispum, Geutbier 
R. Goldenbergi, Weiss 

~ Caulopteris macrodiscus, Brongn. 


Lycoropra.es. 
Sigillaria reniformis, Brongn. . 
S. Voltzia, Brongn. 
S. elongata, Brongn. . 
Stigmaria ficoides, Sterub. 


| 


Bristol Coal-field. 61 


LocaLirizs. 

| Coal Pit Parkfield Puckle- 
Heath. arkfield.) “Ghurch. 

—, x — 

— ye — 

E x (2) f 

He = x 

x | = = 

a — —_ 

xe —d 

as xX = 

a | Xx 7 


We now proceed to record the additions which we have been able to- 


make to this flora :— 


EQUuISETALES. 
pee Suckowi, Bronen. 
’, Cisti, Brongn. , 
ee sp. (external surface) ; 


Annularia sphenophylloides (Zenker) 


Annularia ef. radiata(?), Brongn. 
PYERIDOSPERMS AND FERNS. 
Sphenopteris neuropteroides (Boulay) 


S. ovatifolia, sp. nov. 
Alethopteris Serti (Brongn.) . 
Neuropteris flexuosa, Brongn. 
N. Scheuchzeri, Hottm. 
Pecopteris polymorpha, Brongn. 
P. crenulata, Brongn. : 


IP, ACO ENR) 5 5 4 


Pecopteris (Dactylotheca) plumosa (Artis) . 


Mariopteris muricata (Schloth.) . 
Macrosphenopteris (?) sp. 


Trigonocarpus Noeggerathi (Stern). ) 


Trigonocarpus sp. (outer surface) 
Rhacophyllum spinosum, Lesqx. 
Schizopteris lactuca, Pres] 


LycopPopiaLzs. 


Lepidodendron lanceolatum, Lesqx. 


Lepidodendron cf. L. Glineanwn, Eichw. . 


Lepidophylium majus, Brongn. 
CorDaITAaLEzs. 
Cordaites angulosostriatus, Grand’ Eury 


Locauiry. 
Parktield Colliery. 
Parkfield Colliery. 
Parkfield Colliery. 

( Coal Pit Heath Collier We 


: Parkfield Colliery. 


Shortwood Colliery. 
Coal Pit Heath Colliery. 


{ Coal Pit Heath Colliery. 


* \ Parkfield Colliery. 
; { Coal Pit Heath Colliery. 


Shortwood Colliery. 
Shortwood Colliery. 
Parkfield Colliery. 

Coal Pit Heath Colliery. 
Coal Pit Heath Colliery. 
Coal Pit Heath Colliery. 


( Coal Pit Heath Colliery. 


Parktield Colliery. 


( Shortwood Colliery. 


Shortwood Coiliery. 
Coal Pit Heath Colliery. 
Parkfield Colliery. 

( Coal Pit Heath Colliery. 


- ) Parkfield Colliery. 


Coal Pit Heath Colliery. 
Parkfield Colliery. 
Coal Pit Heath Colliery. 


( Coal Pit Heath Colliery. 


* \ Shortwood Colliery. 


Parkfield Colliery. 
Coal Pit Heath Colliery. 


Coal Pit Heath Colliery. 


DESCRIPTIONS OF THE SPECIMENS. 
Two of the determinations above mentioned have not hitherto been 


recorded from Britain. 


One of these appears to be a new species of 


Sphenopteris, the other a species of Lepidodendron, new to Britain. 


» 


62 D. G. Lillie—Fossil Flora, Bristol Coal-field. 


SPHENOPTERIS OVATIFOLIA, sp. noy. (Pl. VII, Figs. 4 and 5; 
Text-figs. 1-3.) 

Description—Smaller ultimate pinne, alternate, 15mm. long, 
narrow, deltoid in shape. Pinnules ovate or ovate-lanceolate, delicate, 
4-5 mm. in length, 2-2°5 mm. broad, confluent above but separate 
and contracted at the base below, entire when small or lobed when 
larger, margin slightly sinuate or (?) toothed. Terminal pinnule not 
seen. Veins distinct, median nerve not extending to apex, lateral 
nerve single, or once, or more rarely twice, forked, in which case the 
branches fork widely. Nervation of the Renaultia type. (FI. VII, 
Fig. 4; Text-fig. 1.) Larger pinne, more than 25cm. long. Pin- 
nules ovate-lanceolate, contracted at base, 5—6°5 mm. long with six to 
eight or more lobes. (Pl. VII, Fig. 5; Text-figs. 2 and 3.) Pinnules 
sometimes overlapping.’ 

The same species or very closely similar specimens have been 
collected by Mr. Arber from Kilmersden Colliery, Radstock.’ 


aN 
QLD 
Fic.1. Sphenopteris ovatifolia,sp.nov.  Fie.2. Sphenopteris ovatifolia, sp. nov. 
Enlarged pinnules to show the nerya- Enlarged pinnules to show the nerya- 
tion. x 4 times nat. tion. x 4 times nat. 


Fic. 8. Sphenopteris ovatifolia, sp. nov. Enlarged pinnules showing the 
nervation. x 4 times nat. 


A ffinities.—Sphenopteris ovatifolia, sp. noy., differs from Renaultia 
Footnert (Marratt) in the pinnules being much larger, in the rachis 
not being winged, and in the shape of the pinnules. Renaultia 
cherophylloides (Brongn.) was at first thought to be the species to 
which these specimens belonged ; but it is really quite distinct. The 


1 Nos. 2085, 2086, 2087, 2088, 2089, 2090, 2091, 2092, Carb. Plant Coll. 
Sedgwick Mus., Cambridge. 


2 Nos. 1703, 1704, 1705, 1549, in the same collection. 


D. G. Liltie—Fossil Flora, Bristol Coal-field. 63 


pinnules of 2. cherophylloides are more sinuate and much less con- 
tracted at the base than in our specimens. &. schatzlarensis (Stur) 
‘is less like these specimens than 2. charophylloides. The pinnules 
of this species are much more deeply lobed than in our specimens, 
giving the appearance of a much less massive frond, whereas 
S. ovatifolia is less massive than &. cherophyllordes. 


Lepiroprnpron cf. L. Guincanum, Eichwald.’ (Pl. VII, Figs. 1-3; 
Text-figs. 4 and 5.) 


Deseription.—Impressions of stems, 15 X 5 cm., showing two states 
of preservation. The more external impression is probably the 
external surface very slightly decorticated (as seen at @ in Figs, 1 
and 3, Pl. VII, and in Text-fig. 4). The leaf-bases are small, very 
elongate, fusiform in shape, each leaf-base being joined to the one 
above and below by a narrow ridge. Taking the middle points of 
these ridges as the limits of the individual leaf-bases, each leaf-base 
is 1-4cm. long by 1mm. broad across the greatest width. The 
cushion is 6mm. long. ‘The lateral angles are rounded. The leaf- 
scar is not preserved. There is no ridge, or only a slight indication of 
a ridge, on the cushion. There is a well-marked narrow ridge between 
each cushion, which is continuous with the prolongations of the 
cushions above and below as mentioned above. 


if 


Fie. 4. Lepidodendron cf. ZL. Glin- Fic. 5. Lepidodendron ct. L. Glin- 
canum, Kichw. More external surface. canum, HKichw. More decorticated 
5 Bo tee surface. x 3. 


The more decorticated surface (seen at 6 in Pl. VII, Figs. 1 and 3, 
and Text-fig. 5), shows shorter fusiform areas between well-marked 
flat-topped bands 1 mm. in width. 

Attribution of the Specimens.—Though these specimens are not ill 
preserved, yet they do not show the leaf-scar. Consequently they 


1 Nos. 2068, 2080, 2081, Carb. Plant Coll. Sedgwick Mus., Cambridge. 


64 D. G. Litlie—Fossil Flora, Bristol Coal-field. 


cannot be identified specifically. The nearest species appears to be 
Lepidodendron Glincanum, Kichwald, especially the figure on pl. v (a), 
fig.:5 of that author’s Lethea Rossica.. Also another specimen attri- 
buted to this species by Dr. Kidston (pl. v, figs. 41-3),? bears 
a marked resemblance to this fossil. We may, however, first discuss 
some other species with which comparison may be made. The first 
of these is Lepidodendron rimosum, Sternberg, to which Zalessky * 
attributes Dr. Kidston’s figures above mentioned. In the true 
L.rimosum the leaf-bases are much larger, more widely separated 
by striated bark, while in older stems of the same plant the separation 
of leaf-bases is even more marked. The leaf-bases in our specimens 
are much narrower, and more elongate in proportion to their length, 
than’ those of Z. rimosum. Further, the decorticated ‘condition of 
LI. rimosum does not correspond to our specimens. 

Another near species is ZLepidodendron dichotomum (Sternberg ?), 
Zeiller, which, however, we believe to be distinct. Zalessky* has 
pointed out, and we understand that Dr. Kidston agrees, that certain 
of the specimens figured by the latter under the name of Z. Glincanum? 
should now be referred to Z. dichotomum. To return to L. Glincanum, 
our specimen is identical with Eichwald’s® pl. v (a), fig. 5, and 
‘also-to ‘a less extent with figs. 1, 2 2, and 3; figs. 1 and 5 show the 
two stages of decortication, just as in our specimens. The specimens 
attributed by Schmalhausen to the same species—especially of those 
recently refigured by Zalessky ‘—correspond to our more external 
surface very fairly, though the leaf-bases are rather larger and 
the specimens are indifferently preserved. With regard to fig. 14 
the correspondence is very close when compared with the decorti- 
cated surface of our specimen. The only other Se so far 
figured with which we are acquainted are Kidston,® pl. v, figs. 41-3. 
Dr. Kidston’s s specimens do not show the decorticated stage. We must 
note that he calls this a variety ‘rimosum’, while Zalessky refers it to 
the species LZ. rimosum. At any rate Dr. Kidston’s specimens, from 
the River Esk, which he regarded as belonging to the Carboniferous 
Limestone Series, indicate that the locality is almost certainly high 
up in the Coal-measures. 

This group of species, including Z. rimosum, LZ. Glincanum, and 
L. dichotomum, is one which presents many difficulties, and further 
evidence may show that these forms are more intimately connected 
than is supposed. But for the present we have no good grounds for 
regarding them as other than distinct. The fact. that the leaf-bases 
show no definite leaf-scar is also found to be usually the case in 
Lepidodendron lanceolatum, and may be characteristic of some of the 
Upper Coal- measure Lepidodendr Ons. 


1 Eichwald, Taha Rossica, vol. i, ecient Période,’’ p. 127, 

2 Kidston, Trans. Roy. Soc. Edinb., vol. xl, Bt. iv, No. 31. 

S Zalessky, Mémoires du comité géologigue N.S 1908, livraison xiii, p. 88. 

4 Thid:, 1904, livraison xiii, p. 

2 Kidston, Trans. Roy. Soc. Edinb. vol. xl, pt. iv, No. 31, pl. ii, figs. 20 and 
; pl. iv, figs. 37-9. 

ie Bichwald, Lethea Rossica, al i. 

7 Zalessky,: ‘Mémoires du comité géologique, N.S., livraison xiii, pl. iii, fig. 13. 

8 Kidston, Trans. Roy. Soc. Edinb., vol. x1, te iv, No. 381. 


Piatr VII. 


1910. 


Grou. Mac. 


EB. A. N. A. photos. 


Fossil Plants from the Bristol Coal-field. 


ond 


sae 


vate ey tay (he lee) heer 


D. G. Litlie—Fossil Flora, Bristol Coal-field. 65 


The following list contains a complete record of the plants 
at. present known from the four divisions of the Bristol district. 
It will be seen that the flora of the Farrington Series‘ has been 
increased by twenty-one species, while the fossil flora of the Pennant 
Rock, the New Rock Series, and the Vobster Series remains as 
Dr. Kidston! recorded it, without a single addition. 


FARRINGTON SERIES. 


Coal Pit | 


ane ey is 
EQuisEraLEs. Eicathy ‘Parkfield. Short peels 


wood. | church. 
Calamites ramosus (Artis). 2... Xx x Bua Melia os 
OL Snothand, inten, = 95% 6) 5 - 
C. Cisti, Brongn. ; beaten ~ 
Culamites (external surface) 
Annularia stellata (Schloth.) . 

A. sphenophylloides (Zenker) . , 
Annularia ct. radiata (?), Brongn. . 


I ectaisber ant 


AMA I 
| mw | 
| 


SPHENOPHYLLALES. 
Sphenophyllumemarginatum, Brongn. 


i 
4 
| 
| 


PrERIDOSPERMS AND FERNS. 


a 
| 
{ 


Sphenopteris neuropteroides (Boulay) 
S. ovatifolia, n.sp. . . aie 
Alethopteris Serh (Brongn. ) 

A. lonchitica (Schloth.) . 
Neuropteris flexuosa, Sternb. 

N. macrophylla, Brongn. . 

NV. ovata, Hoffman . ; 

N. Scheuchzeri, Hoffman . . . 
Pecopteris arborescens (Schloth.) . 
P, polymorpha, Brongn. 

P. crenulata, Brongn. 

P. Miltoni (Artis) Saae 

P. (Dactylotheca) plumosa (Artis) 
P. oreopteridia, Schloth. 

JP, pteroides, Brongn. : 
Mariopteris muricata (Schloth. yc 
Macrosphenopteris (2) sp... 
Lrigonocarpus Noeggerathi (Sternb. ) 
Trigonocarpus (outer surface). . 
Rhacophylium spinosun, Poa 

Rk. crispum, Gutbier . 

Rk. Goldenbergi, Weiss . 
Schizopteris lactuca, Pres] 
Caulopteris macrodiscus, Brongn. 


[LAR RA A 


bee ey 
l 


ml 
eksh Wistar Ap ret ll 


| aww 
Lew LR 
| 


Hepes 1 ae at 
| 
| 


[Ren ISK A | or A | oR 
| 


kat Il 


vai 
| 
| 
| 


LycopopirALeEs. 


Lepidodindron lanceolatum, Lesqx. 
Lepidodendron cf. Glineanum, Kichw. 
Lepidophyllum majus, Brongn. 
Lepidophyllum (?) sp. 
eee reniformis, Bronen. 
. Voltzia, Brongn. 
. elongata, Brongn. 
Sigillavia(?) sp... 
Stigmaria ficoides, Sternb. 


CorDAITALES. a i 
| 


Cordaites angulosostriatus,Grand’ Eury x - = = 


1 Kidston, Trans. Roy. Soc. Edinb., aa xl, pt. iv, No. 31, 
DECADE V.—VOL. VII.—NO. Il. 


wn | 
A | 


WlAw ThA 
| 
rR I 


l 
I 
I 
| 


5 


66 D. G. Lillie—Fossil Flora, Bristol Coal-field. 


Sma A “PENNANT ROCK. 
mney Downend paces 


Calamites Suckowi, Brongn. . +. + + + - x = = 
C. canneformis, Schloth., sp-? . - . - - Ki = a 
C. approwimatus, Brongn. . - - + + + + | x x x 


5 


EQuISETALES. 


LYCOPoDIALES. 


CUMOAENON ON. zien 3 RB Paso Ta) = x = 
SDETGLONUG fog ets oe RAN tee Oto Sie Sd Reny - = = x 
Stigmaria ficoides, Sternb. . . - - - . . near Bristol. 


NEW ROCK SERIES. 
Kangs- | Kings- | 
Kings- | wood, | wood, | Warm-| Golden} Bed- 


f i : wood. | Deep | Speed-| ley. | Valley. |minster. 
HQuisErarns. Pit. | well Pit.| 


Calamites Suckowi, Brongn. x ~ uf 


PrERIDOSPERMS AND FERNS. 


Sphenopteris trifoliata (Artis) ies x ks Bu a nt 
Pecopteris arborescens(Schloth.) a ies ui 
P. Miltoni (Artis) . : : 


LycoropDIrALEs. 


Lepidostrobus sp. 
© Ulodendron ’ Re hc 
Sigillaria monostigma, Lesqx. 
S. tessellata, Brongn. . : 
S. mamillaris, Brongn. 

var. abbreviata, Weiss . 
S. scutellata, Brongn. 
S. rugosa, Brongn. 
S. Schlotheimi, Brongn. . 
Stigmaria ficoides, Sternb. 
Cordaites (?) sp. 


I 3 
eal 
wn | 
| 
| 
| 


| Monee el 
| 
| 
| 
| 


VOBSTER SERIES. 


SPHENOPHYLLALES. 

Sphenophyllum emarginatum, Brongn. . . . . . . ~~ ~ ~ Ashton. 
PreRIDOSPERMS AND FERNS. 

Pecopteris oreopteridia (Schloth.) . . . . . .. . + . . . Ashton. 
LycoPODIALEs. 

Sigtllaria Sillimani, Brongn. . . . . . «. - - . . - - » , Ashton. 

S. mamillaris, Bronpm. . . se ke 


A ComPaRISON oF THE FroRA OF THE FARRINGTON SERIES IN THE 
Bristot AND Rapstock Disrrictrs. 


Fifty species in all have been recorded from the Farrington Series of 
the two districts. Seventeen of these are common to both the Bristol 
and Radstock areas, while twenty occur at Bristol which have not yet 
been found at Radstock, and thirteen at Radstock which are as yet 
unknown from Bristol. We have thus thirty species from the 
Farrington Series in the Radstock district; and thirty-seven species 
from the same series in the Bristol district, sixteen of which were 
recorded by Dr. Kidston and twenty-one by the present writer. 


Prof. G. Delépine—Faunal Succession, Llantrisant. 67 


Turning now to a comparison of the Radstock and Farrington Series, 
only four out of the fifty species known from the Farrington Series 
are as yet unrecorded from the Radstock Series, which confirms 
Dr. Kidston’s surmise that the two series belong to the same paleo- 
botanical horizon, namely, the Upper Coal-measures. The four plants 
from the Farrington Series which have not yet been definitely found 
to occur in the Radstock Series are the following :— 

Sphenopteris ovatifolia, n.sp. 

Schizopteris lactuca, Presl. 

Lepidodendron ct. Glincanum, Kichwald. 

Sigillaria principis, Weiss. 
But as mentioned above (p. 62), a Sphenopteris, very like S. ovatzfolia, 
has been found in the Radstock Series of Somerset, at Kilmersden, by 
Mr. Arber. 

In conclusion, I would express my special thanks and indebtedness 
to Mr. Arber for suggesting that I should take up the work in the 
first place, and for continued help and advice throughout. Many 
thanks are due to Mr. H. Bolton, F.G.S., of the Bristol Museum, for 
his kindness in handing over to me the petrified material from Staple 
Hill for examination; and to Mr. James McMurtrie, F.G.S., of Bristol, 
for much local help and information. we 


EXPLANATION OF PLATE VII. 
(Photographs by Mr. Arber.) 


Fic. 1. Lepidodendron cf. L. Glincanwm, Kichw. Stem showing two states of 
preservation—(a) shghtly decorticated outer surface showing the. leaf- 
bases, but not the leaf-scars; (6) more decorticated state. x 3. 
No. 2080. Sedgwick Museum, Cambridge. 
>, 2. Thesame. Portion of the slightly decorticated outer surface, showing the 
leaf-bases. x 2. No. 2068. 
Portion of the same stem as Fig. 1, showing two similar states of decortication. 
Sphenopteris ovatifolia, sp. nov. Typical pmne. x 2. No. 2089. 
Sphenopteris ovatifolia, sp. nov. A portionofafrond. x %. No. 2086. 


OV He OO 
er een 


IIJ.—Nore on tHe Fauna Succession 1n THE CAaRBONIFEROUS LIME- 
STONE (AVONIAN) NEAR LLANTRISANT STATION IN THE BRIDGEND 
Area, SourH WaALEs, 


By G. Drxépine, Professor of Geology at the Catholic University, Lille. 


URING the autumn of 1909, I made a short excursion into the 
Bridgend district and examined the Avonian sequence near 
Llantrisant. The present note embodies the results of a few traverses 
and suggests a correlation with the sequence already established at 
other points of the South-West: Province. 

I herewith acknowledge my indebtedness to Dr. A. Vaughan, F.G.S., 
for the loan of specially prepared 6 inch maps, and for help in drawing 
up the faunal lists given below.! 

The strike of the limestone is generally W.S.W. and the dip 
N.N.W.. in the neighbourhood of Llantrisant and Llanharry (see 


} The specific identification is that adopted by Dr. Vaughan in his papers on the 
Avonian. 


s 


68 Professor G. Delépine—Faunal Succession— 


sketch-map), but near Ystradowen the beds turn over locally and dip 
S.8.E. (see the new 1 inch map, Geological Survey, Sheet 262). 


—) 


SR 


| Llanharry. 
ae 
7? 


Sketch-map of the Carboniferous Limestone exposures near Llantrisant Station. 


I. Exposures Kast of Llantrisant Station, North of the Great Western Line. 

(1) About half a mile east of Miskin church (sketch-map, letter a) 
there are several small and scattered exposures which exhibit a thin- 
bedded dark-grey encrinital limestone. From these beds I obtained 
the following Brachiopods :— 


Productus burlingtonensis. Syringothyris cf. typa, Weischell. 
Chonetes cf. hardrensis. Reticularia cf. lineata. 
Orthotetid. Athyris ct. glabristria. 
Rhipidomella Michelini. Rhynchonellid. 


Spirifer clathratus. 

Bryozoa, especially Fenestellids, are very abundant. 

(2) About 200 yards north of exposure a, in an old quarry (exposure 
6) near the school, black and dark-blue encrinital limestone occurs at 
the bottom and dolomite with crinoids above. 

The limestone yiclded— 

CoraLs, 

Zaphrentis sp. 
Caninia cornucopia. 

BracHIoPops. 
Productus burlingtonensis. 
P. cf. pustulosus. 
Chonetes cf. hardrensis. 
Spirifer clathratus. 
Syringothyris laminosa. 


Carboniferous Limestone, Llantrisant. 69 


The dolomite yielded— 
Caninia cornucopia. 
Syringothyris cuspidata. 
S. laminosa (very common), 
(3) In a quarry near Hendy Farm, along the road from Miskin to 
Pontyclun (exposure ¢), encrinital dolomite and massive oolite are 


observed. 
Fauna. 
Cyathophyllum o. 
Productus corrugatus, var. 
Syringothyris cuspidata. 
S. laminosa. 
Athyris ingens, de Kon. (= Athyris ct. glabistria, mut. C-S). 

(4) Along the road, north of Miskin, which joins the main road 
from, Llantrisant to Cardiff, there are two quarries, to left and right 
of the road respectively. 

In the first of these (exposure @) the ascending succession is as 
follows :— 

Encrinital dolomite and oolite. 

Thin-bedded black limestone (‘ china-stone ’). 
Massive oolite. 

Blue and grey well-bedded limestone. 

The dolomite at the base contains the same fossils as exposure ¢ 
near Hendy Farm. 

The upper beds contain— 

Lithostrotion Martini. 
Productus corrugato-hemisphericus. 
Seminula ficoides (abundant). 

The second quarry (exposure ¢) lies to the north of the last, and 
about 100 yards distant. 

The oolitic hmestone here contains— 

_ Productus cf. corrugatus | 
Prod. corrugato-hemisphericus - All abundant. 
Seminula ficoides J 

As has been previously noticed, a variant of Prod. corrugato - 

hemisphericus approaches close in form to Prod. striatus. 


Ia. Correlation of the Limestone East of Llantrisant with the Avonian 
of the South-West Province. 


The exposures described above fall readily into the following 
positions on the zonal scale :— 


: § S.= Exposure e. 
SERN Lake (8, =Exposure d (top of quarry only). 


fae Wxposure ¢ and bottom of Exposure d. 
Caninia-zone ee of C, (y) = Exposure 6. 


Zaphrentis-zone (pars) = Exposure a. 


II. Exposures West of Llantrisant Station, near Llanharry. 


There are several quarries in 8, and Lower D on the left of the 
road from Bryn-Sadler to Llanharry. 
(1) Im a quarry some half-mile south-west of Llanharry Station. 


70 Prof. G. Delépine—Faunal Succession, Llantrisant. 


(Taff Vale Railway) and on the road from Llanharry to Ystradowen 
(exposure f) the following fossils occur in a massive oolite :— 
Lithostrotion. 
Carcinophyllum. 
Prod. corrugato-hemisphericus, mut. Sz. 
Seminula ficoides. 

(2) A large quarry and several small ones. 

Above. this oolite, in a very large quarry (exposure g) north of, 
and close to, Llanharry Station, a well: bedded blue and violet lime- 
stone is massively developed. 

Here the beds are poorly fossiliferous, but in another quarry 
(exposure /) where the upper beds are worked I collected— 


Carcinophylium @ and fragments of Campophyllum and Productus. 


In a quarry to the east of the last, near a chapel, on the other side 
of the Taff Vale line, a similar limestone occurs (exposure /). This 
yielded Productus hemisphericus, Chonetes sp., and Gasteropods. 

(3) Close to the village of Llanharry, on the left-hand side of the 
road from Bryn- Sadler, is an old quarry (exposure m) exhibiting 
thick beds of rubbly limestone. Here I collected— 

Lithostrotion irregulare. 
Dibunophylium 6. 


Productus near Martini. 
Seminula ficoides. 


Ila. Correlation of Limestone West of Llantrisant with Avonian Zones. 


D,.= Exposure m. 
D, =Exposure /, and perhaps top of large quarry (g). 


Dibunophyliun-zone 
Seminuia-zone. §,= Exposure f and bottom of large quarry (g). 


III. About one mile north of Ystradowen, on both the right and 
left of the main road from Llantrisant to Cowbridge, the beds dip in 
a south-easterly direction. 

A quarry on the right (exposure ») exhibits dolomite with 
erinoids; the base of the dolomite yielded— 

Syringothyris laminosa (abundant). 
Syr. cuspidata (common). 
Caninia cornucopia. 
A quarry on the left (exposure 2) exhibits, in ascending order— 


(1) Massive oolite. 
(2) Dolomite with crinoids. 
(3) Black limestone. 
The beds in (m) and (xz) resemble, both lithologically and 
palzontologically, the oolitic and dolomitic beds of exposure (¢), near 
Hendy Farm, which have been assigned to Cy. 


(GlOvyes BNE os 03 
Dibunophyllun-zone ; 1D. aie a tceeneey: 
Zonal Seminuta-zone { ©? e, f, bottom of 7. 
Sequence US. . Top of d. 
Oaitninenee. Cy 2). 3) 2) Bottom onde, 7a 
\ Base of C, (y) 2. 


Lapnrentis-200e)) se in nea 


Dr. John Ball—The Nile Valley and Gulf of Sues. ual 


TV.—On tur Ornrern or tHE Nine VALLEY AND THE Gutr oF Surz.! 
By Joun Barz, Ph.D., D.Se., F.G.S. . 


ia Captain Lyons’ Physiography of the River Nile and its Basin 
(Cairo, 1906, p. 294), there occurs the following statement :— 
‘¢TIn a trough from 2 to 10 kilometres wide and 100 to 300 metres 
deep lies the Nile, meandering through a flood plain formed by yearly 
deposits of silt brought down from the Abyssinian table-land by the 
Blue Nile and the Atbara. This trough was determined in the first 
instance by fractures of the crust which caused a strip of country from 
about Edfu (lat. 25° N.) to Cairo to be depressed, leaving the plateau 
standing high above it, just as the Red Sea and the gulfs of Suez and 
Akaba were formed, probably about the same epoch. This interference 
with the drainage of the country doubtless produced a series of lakes 
in the low-lying area, while the drainage of the eastern plateau com- 
menced to excavate the valleys which now exist as dry desert wadies, 
their development being in many cases far from complete, as shown by 
the cliffs which interrupt the slope of the valley when a harder bed 
of rock than usual is met with. 
‘‘ Into this depressed area the drainage ot the southern part of the 
basin finally flowed, and there laid down the alluvial deposit through 
which the river flows to-day.” 


A clear and definite pronouncement of this kind, coming from so 
high an authority as the former Director-General of the Geological 
Survey of Egypt, is likely to convey the impression that the ‘ nft 
theory ’ of the origin of the Nile Valley and Gulf of Suez is supported 
by evidence which leaves no room for any other view. This is very 
far from being the case. ‘To my mind the field-evidences are entirely 
against the ‘rift theory ’; they point rather to the Nile Valley being 
essentially a valley of erosion (though faults or lines of weakness may 
have had something to do in influencing the river’s course), and to the 
Gulf of Suez being an eroded anticline. 

During my twelve years of survey work in Egypt, most of which 
has been spent in geologizing, I have felt myself becoming increasingly 
sceptical as to the truth of the ‘ rift theory’ of the orgin of the Nile 
Valley and the Gulf of Suez. But it was not till the spring of the 
present year, when I examined the geological structure of the Wadi 
Araba and part of the Gulf of Suez, that I obtained evidence which 
appears to be absolutely convincing against the ‘rift’ view cited above. 

The Wadi Araba is a great valley some 20 miles wide, draining 
north-eastwards into the Gulf of Suez between latitudes 29° 3’ and 
29° 22’N. It divides two great plateaux, the North and South 
Galala Mountains, which rise to heights of over 4000 feet. . The faces 
of the plateaux which shut in the valley are steep cliffs, in which are 
exposed a great thickness of Eocene limestones, overlying Cretaceous 
limestones, marls, and clays, with Nubian Sandstone at the base. The 
beds, especially the lower ones, havea well-marked dip into the scarp, 
showing the valley to be an eroded. anticline; and this structure is 
confirmed by the fact that as one crosses the valley, deeper and deeper 


1 By permission of the Director-General, Survey Department. 


72 Dr. John Ball—The Nile Valley and Gulf of Suez. 


sandstone-beds come to the surface, until near the centre of the valley 
one comes on Carboniferous rocks in the form of thin limestone-beds, 
intercalated in the sandstones, with abundance of such characteristic 
fossils as Spirdfer and Productus. There is no apparent unconformity 
anywhere in the series. ‘The upper sandstone beds, which are devoid 
of fossils, may therefore be here, as in the Nile Valley, of Cretaceous 
age, though the lower ones are certainly Carboniferous. ‘The apparent 
absence of any unconformity between Cretaceous and Carboniferous 
is a very striking fact; but it is not material to the argument con- 
cerning structure, the great point in this connexion being the absolute 
proof, furnished by the succession of fossiliferous beds, and their dips, 
that the Wadi Araba is an eroded anticline, and thus the very opposite 
of a rift or trough-fault. 

Another very significant feature of the valley is the way in which 
great masses of the hard Eocene lmestones have been let down by 
landslips at the faces of the limiting scarps, often forcing the softer 
Cretaceous beds below them outwards into highly-tilted, or even 

‘nearly vertical, positions. ‘Two causes may have worked to produce 
this. The softer, lower beds may have been eroded out so as to under- 
cut the upper, harder ones, and bring about their fall; cracking of the 
beds may have occurred during the formation of the anticline, which 
would help in the separation of the masses. Further, it would appear 
at least a possible explanation that the stresses set up by the daily 
expansion and contraction of the plateau-surface under the influence of 
the enormous diurnal variation of temperature may have produced 
clefts near the free edges of the plateaux ; and masses detached in this 
way on even a slight slope would tend to creep lower and lower under 
continual expansion and contraction. But whatever the cause of this 
faulting-down at the face, it is at least certain that it is only land- 
slipping on a large scale, and has nothing to do with the main 
tectonic structure of the valley. The Wadi Araba is an eroded 
anticline, its limiting scarps showing in places a step-like structure, 
due to local slipping down of the hard upper strata at the cliff-face. 

I have dwelt thus long on the Wadi Araba, because, while it 
presents the same phenomena as the Nile Valley and the Gulf of Suez 
on a magnificent scale, it possesses also the advantage, not shared by 
them, of being entirely exposed, so that one can examine its floor 
with the same care and detail as its sides. If the floor of the Wadi 
Araba were covered with alluvium or water, we should have an almost- 
exact resemblance to the Gulf of Suez and the Nile Valley. 

Turning now to the Gulf of Suez, which lies in close connexion 
with the Wadi Araba, though at right angles to it, an exactly similar, 
albeit somewhat more restricted, series of observations can be made. 
Leaving the Wadi Araba, I journeyed northwards along the coast, 
skirting the scarps of the North Galala plateau, which in places come 
so abruptly down to the sea that camels have to wade through the sea 
to round the bluffs. The Carboniferous beds, with their characteristic 
erinoids, were traced as far north as 29° 30’ of latitude, showing 
clearly that the eastern foot of the North Galala plateau exposes 
Carboniferous strata at its base. The North Galala plateau is thus 
thrust upwards along the western shore of the gulf, the beds dipping ~ 


Dr. John Ball—The Nile Valley and Gulf of Suez. 73 


generally westwards. This is confirmed by the gradual rise eastwards 
of levels of the springs, and of the junction of Cretaceous and Kocene 
beds as one skirts the north scarp of Wadi Araba. 

My observations of the other side of the gulf were sally telescopic. 
But even casual scrutiny of the hills of the opposite shore (Gebel 
Hammam) showed the beds there to be dipping markedly away 
from the gulf. Telescopic observations of geological structure are 
always to be received with caution, but in this case my observations 
are confirmed by those of my late lamented colleague, Mr. Barron, 
who, from an actual examination of the place, records! that the strata 
of Gebel Hammam dip 10° eastwards. 

So far as general structure goes, therefore, the beds on the two sides 
of the Gulf of Suez dip away from the gulf, showing the gulf to be an 
anticline. 

The seaward faces of the North Galala plateau exhibit in many 
places a step-like form due to the faulting down of the strata in the 
same manner as those of the Wadi Araba, and at several points the 
faults are cut through by small lateral valleys which allow of their 
easy examination. The impression produced in all these cases is that 
of land-slipping at the face of the scarp, and not that of the letting- 
down of a tract extending across the gulf. One of the best exposures 
is the north face of a hill-mass in latitude 29° 34’, close to the north- 
east corner of the North Galala plateau. I climbed this hill, on which 
I had a trigonometrical station 1295 feet above sea-level, and found 
its lower part to be composed of yellow-brown and white lmestone 
and marls (Cretaceous), while its upper part was mainly hard lime- 
stone, which I believe to be chiefly Eocene with a thin covering of 
Miocene. ‘The whole of the beds dipped strongly (18° to 25°) towards 
the main scarp. Standing on the hill-top, one can see, high up on the 
main scarp to the west, the same Cretaceous limestones and marls 
which form the foot of the hill, while the hard Hocene limestones cap 
them at a height of over 2000 feet. Proceeding a short way along 
the coast north of this hill, one can obtain a very clear view of the 
faulting. The fault or slip-plane is inclined at only 22° to the 
horizontal, of course downward from the scarp, and the faulted-down 
Eocene limestones of the hill abut against the purple and brown 
sandstones and clays (possibly in part Carboniferous) which form the 
lower part of the main scarp. ‘he flat angle of the fault-plane is 
significant, and points far more to a great landslip at the face of the 
scarp than to organic faulting of the earth’s crust. The high dip 
of the slipped-down beds towards the scarp is also entirely against 
trough-faulting of the gulf; for if the beds ever extended far seawards 
with anything like the same dip, they would have attained a height 
much greater than that of the main plateau. ‘The conclusion seems 
justified, therefore, that the faulting along the shore of the gulf is 
purely land-slipping, and has nothing to do with the main tectonics 
of the gulf. In other words, the Gulf of Suez, like the Wadi Araba, 
is not a trough-fault, but an eroded anticline. 


' Topography and Geology of the Peninsula of Sinai (Western Portion), Cairo, 
1907, p. 30 


74 Dr. John Ball—The Nile Valley and Gulf of Sues. 


It will of course be remarked that an immense amount of erosion 
must have gone on in the gulf to remove the folded-up strata, while 
the trough-fault theory would not demand this. But one has to 
remember that in the case of the Wadi Araba there can be no doubt 
of erosion on this immense scale having taken place; for it is 
impossible to doubt the original continuity of the Eocene over the 
Wadi Araba, and the Carboniferous beds in the wadi-floor show that 
the Eocene has not been faulted down, so that it must have been 
eroded out. Vast ages must have been occupied in this erosion, even 
if it took place part passu with the folding of the anticline. But with 
the greater space of time which physicists now allow us for the earth’s 
evolution since the discovery of radio-active minerals, geologists will 
not feel that the time demanded for the erosion is any obstacle to 
believing it to have taken place. 

The conviction that the Gulf of Suez is an eroded anticline and not 
a trough fault at once removes an important support from the ‘rift 
theory’ of the Nile Valley. For both the Nile Valley and the Gulf 
of Suez have on this theory been regarded as due to carth-movements 
of similar type acting about the same time, and if we show the 
movements postulated to have been non-existent in the one case, 
a doubt at once arises about the other. 

I have made a search through the various publications to find out 
the history of the ‘rift theory’ as applied to the Nile Valley and the 
evidence relied on for its support. The earliest reference published 
appears to be in a paper read by my friend and former colleague 
Mr. Beadnell at the International Geological Congress at Paris in 
1900, an abstract of which appeared in the Gronoeican Macazinn 
of January, 1901 (p. 23). Though Mr. Beadnell informs me that he 
no longer considers the trough-faulting of the Nile Valley to be 
a necessary conclusion from his observations, he has set out so clearly 
in his paper the only grounds on which the ‘rift theory’ rests, that it 
is advisable to quote them here as affording a definite basis for 
discussion. The facts which led Mr. Beadnell to the view that the 
Nile Valley had its origin in carth-movements and was not the result 
of erosion are as follows :— 


(1) The general north and south direction of the Nile Valley in 
Egypt. 

(2) The remarkable high, lofty, wall-like cliffs by which it is 
hemmed in. 

(3) The absence of any true river-deposits at any considerable height 
above the river. 

(4) The almost entire absence of hills or outliers of the plateau 
within the valley. 

(5) The proved existence of bounding faults throughout a long 
stretch of the valley. 


The whole weight of the evidence lies in the last fact given, the 
first four having but little significance in themselves. As regards the 
general direction of the valley, it is by no means straight; the greater 
part of it is approximately parallel with the Gulf of Suez, but if that 
gulf is not a trough there is no argument by analogy of direction. 


Dr. John Ball—The Nile Valley and Gulf of Suez. 790 


The nature of the cliffs is no more evidence of faulting here than 
in the case of the Grand Caton of Colorado. Moreover, cliffs of the 
same character occur in many lateral valleys, and any argument as to 
the one applies equally to the other; this difficulty was clearly 
perceived by Dr. Blanckenhorn,! who in accepting the trough-fault 
theory for the valley ascribed the origin of many of the lateral wadies 
to faulting. The absence of high river-terraces is easily explained by 
the frequent landslips at the face of the scarp and the action of the 
sand-blast through long ages. Outliers of the plateau within the valley 
would necessarily be infrequent on a theory of river-erosion without 
faulting. As to the bounding faults, there is no doubt whatever 
of the accuracy of Messrs. Barron and Beadnell’s observations of 
the facts. I have seen many of the places myself and confirmed their 
sections. But one may dissent from their interpretation. The faulting 
observed is by no means continuous; it is most pronounced where soft, 
shaly beds have formed the base of the main scarp; no observation 
has ever been made of faulted-down rocks far from the scarps; and 
the faulted-down portions are exactly similar to those which occur 
in the oases, in the Wadi Araba, and along the coast of the Gulf 
of Suez, wherever there is an exposed face of a great plateau without 
any suggestion of trough-faulting. The true interpretation of the 
bounding faults of the valley is that they are landslips, and have 
nothing to do with the primitive formation of the valley. The valley 
was croded first, and the landslips occurred afterwards. Faults or 
lines of weakness may have influenced the path of the river in its 
early stages, but the material which formerly extended from cliff 
to cliff has been removed seawards by erosion, not let down under 
the present Nile-bed. The great eastern wadies were formed con- 
temporaneously with the Nile Valley by the same process of erosion, 
being the paths of tributary streams. They are on a scale quite 
comparable with the main valley, and there is no evidence whatever 
to support the view expressed by Captain Lyons that they originated 
after the main valley was formed. That the Nile Valley is geologically 
young is undoubted, but I know of no facts which would support the 
belief that it is of insufficient age for it to have been entirely excavated 
by erosion. 

After coming to the above conclusion, I have had the pleasure of 
discussing the matter with Mr. Beadnell, who informed me that he 
has for some time abandoned the trough-fault interpretation of his 
observations, and he authorizes me to state that he has lately convinced 
himself that all the faults along the scarps of the Nile Valley can be 
explained as landslips, the harder limestones having slipped down 
over the softer underlying shales which have been eroded by the river. 

ConcLusions. 

(1) The hypothesis that the Nile Valley and the Gulf of Suez owe 
their origin to trough-faulting is unwarranted by geological evidence. 

(2) The Gulf of Suez is an eroded anticline. 

(3) The Nile Valley is essentially a valley of erosion, and the 


1 «¢ Geschichte des Nilstroms’’: Zeits. fiir Erdkunde, Berlin, 1902. 


76 R. M. Brydone—New Chalk Polysoa, ete. 


eastern wadies draining into it were formed contemporaneously, also 
by erosion. 

(4) The faulting, which can be observed along the faces of the 
bounding scarps of the Nile Valley, Gulf of Suez, and the eastern 
wadies, is the result of landslips subsequent to the erosion of the 
hollows. 


V.—Nores oN NEW OB IMPHBRFECrLY KNowN CHALK Poryzoa. 
By R. M. Bryponz, F.G.S. 
(PLATE VIII.) 
(Continued from the January Number.) 


Memeranipora Inviertata, nov. Pl. VIII, Figs. 1 and 2. 


Zoarvum adherent. 

Zoewcia roughly elliptical, length ‘60 to -68mm., width ‘86 to°40mm., 
length of area °36 to -40 mm., width -24 to -28 mm.; they have broad 
side walls, whose upper surfaces slope slightly to the area; at the 
foot there is generally a fair amount of external front wall, which 
often carries its own accessory avicularium or the ocecium of the 
preceding zocecium; the walls of adjacent zocecia are always 
distinguishable and very often not in contact. 

Owcia abundant but very. rarely preserved, globose, with a small 
part of the under edge free. 

Avicularia of two types. (@) Accessory: these are small semi- 
circular tubular prominences developed on a semi-elliptical platform 
pushed out over the external front wall below the level of the rims of 
the area; they are directed forwards, looking over the area and some- 
times overhanging it; sometimes the platform is formed without any 
further development, except perhaps a perforation. (6) Vicarious: 
these are long and narrow, widest at the head and tapering gently to 
the foot; aperture similar in outline, but with a construction of very 
variable degree near the foot, and bounded at the head by a broad 
internal shelf at some depth, which tapers rapidly towards the middle, 
where it disappears; at this point the bounding walls are folded over 
so that the outer edge in the upper part becomes the inner edge in the 
lower (well shown by the avicularium, which in Fig. 1 is immediately 
to the left of the only ocecium preserved). 

Fairly common at Trimingham and in the zone of Jheraster cor- 
anguinum at Gravesend, and I have found what may be a spinose 
stage of it in the zone of Actinocamax quadratus. ML. trigonopora, 
Marss., has a general resemblance to this species, but has no vicarious 
avicularia, while this species has not the tiny pores of I. trigonopora. 


Memeranipora Brrrawnica, mihi. Pl. VIII, Figs. 3 and 4. 


I take this opportunity of giving photographs of the type-specimen 
(Fig. 3), and another with finely developed avicularia (Fig. 4). In 
a Membranipora so abundant almost any micrometric measure can be 
obtained, but ‘36 to ‘48 mm. for length of area and ‘28 to ‘32 mm. for 


PLATE VIII. 


Chalk Polyzoa. 


R.M. Brydone photo. 


S 
ee 
(oP) 
ei 
& 
< 
al 
= 
S 
| 
td) 
as) 


R. M. Brydone—New Chalk Polysoa, etc. Tih 


width of area seem fairly representative. The specimen shown. in 
Fig. 4, though very exceptional in its large and graceful avicularia, 
quite 99 per cent. of specimens conforming closely with the type, 
raises an interesting question whether Fig. 3 ought to be regarded as 
the true standard and Fig. 4 as a sport, or whether Fig. 4 ought to 
be regarded as the true standard and Fig. 3 as due to mechanical 
gauses—attrition and solution—or to the general prevalence of some 
local condition unfavourable to a full development of the avicularia. 
As the two specimens grew contemporaneously and under identical 
conditions, so far as can now be judged, the question is more acute 
than in such a case as Cribrilina Gregoryt, where the avicularia 
are mere rings. until we get high up in the zone of Act. guadratus, 
where they become mandibular. 


Mempranipora Brirannica, var. prR&cuRsOR, nov. Pl. VIII, Fig. 5 


This is the form which occurs in the Upper Senonian, especially in 
the zones of Act. quadratus and Belemnitella mucronata. The zocecia 
are distinctly shallower, longer, and wider than in the type, the walls 
of adjacent cells are practically always distinguishable, and the 
avicularia lie practically on their backs and along the surface of 
the zoarium and with their long axes nearly parallel to those of 
the zocecia. The ocecia are so fragile that I have not yet seen one 
preserved. Length of area 48 to -64mm., width ‘36 to -40 mm. 


Mempranipora Britannica, var. DeMIssa, nov. Pl. VIII, Fig. 6. 


This form occurs not unfrequently at Trimingham. It is inter- 
mediate between the type and the var. precursor in that its avicularia 
lie along the surface of the zoarium, with their long axes nearly 
parallel to those of the zoccia, but distinctly on their sides. It is 
clearly distinguished from both by its pyriform zocecia with consider- 
able extent of front wall. The type does, it is true, often show a 
local tendency towards a pyriform zocecium with front wall, but this 
always appears to be due either to crowding, which forced the 
zocecium to grow some distance before it could open out its area, or 
to the failure of the preceding zocecium to produce an av icularium’ or 
an ocecium to occupy the space provided for it; the tendency does not 
go farther than may be seen here and there in Fig. 4. In the 
var. demissa the pyriform shape is obviously a fundamental character 
(which might be held to justify a specific separation), and is developed 
concurrently with the provision for the avicularium of the preceding 
zocecium. Besides these specific points of difference there is a con- 
siderable difference in matters of degree which is incapable of any 
exact definition, but which makes the variety readily recognizable 
with a pocket magnifier. Length of area -36 mm., width ‘32 mm. 


EXPLANATION OF PLATE VIII. 


Fic. 1. Membranipora invigilata, Chalk of Trimimgham. x 20. 

;, 2. Ditto, another specimen. Ditto. x 20. 

ir Ore Membr anipora Britannica, type- Syseuaee. Ditto. x 20. 

», 4. Ditto, another specimen. Ditto. x 20. 

Woes, Ditto, var. precursor. Zone ot Actinocamax saan atus, Wanchiesiar. x20. 
BB 


; Ditto, var. demissa.- Chalk of Trimingham. «x 20. 


78 J. W. Jackson—Archeosigillaria in Westmorland. 


VI.—On rue Discovery or ArcwmosregiLLARiA VAnuxemt (GOPPERT) 
at Mratnor Frnt, WEsTMorLAND, wiTa A Description OF THE 
Locatiry. 

By J. Witrrip Jackson, F.G.S., Assistant Keeper of the Manchester Museum. 

N September last I discovered a number of plant remains in the 
| Carboniferous Limestone at Meathop Fell, Westmorland, amongst 
which were several fragments of what, at first sight, looked like 
a species of Lepidodendron. A closer examination, however, of one or 
two of the better preserved specimens, which showed traces of leaf- 
sears, at once suggested Archeosigillaria Vanuxemi, specimens of which 
I had previously seen in the Kendal Museum. 

On a later visit to Meathop Fell I was successful in obtaining 
a number of other fragmentary specimens of the same plant, along 
with a specimen of a cone, which from its position and association 
with branches of 4. Vanuxemi, has every appearance of belonging to 
that species. Unfortunately the branch beari ing it is so badly preserved 
that no definite details can be made out, ene there is no conclusive 
proof that it belongs to the above species. ‘his is all the more 
unfortunate, as, up to the present, the fructification of this interesting 
plant is unknown. 

The majority of the plant-remains found appear to be referable to 
‘the above species, but one or two specimens occurred which looked 
like the flattened stems of other plants. The identification of these, 
however, is impossible, owing to their badly preserved condition. 
I also cbtained a portion of the stem of Bothrodendron sp., which will 
be referred to later. 

The present discovery of A. Vanuxemi constitutes the third 
recorded occurrence of the species in Britain. The first British 
specimens, which are in the Kendal Museum, were brought to the 
notice of Dr. Kidston by Mr. R. Bullen Newton, F.G.S., and were 
described in 1885 as Lycopodites (Sigillaria) Vanuxemi.! These 
specimens were collected from the lower beds of the Mountain 
Limestone, near Shap Toll-bar, Westmorland. In 1899 Dr. Kidston 
created the new genus, Archaosigillaria, for the reception of this plant.” 

The second discovery was made near Dyserth, North Wales, by 
Dr. Wheelton Hind, F.R.C.S., etc., and Mr. J. T. Stobbs, F.G.S.* 
Here the species was fairly common, and was associated with a fauna 
characteristic of So. 

It may be of interest here to call attention to the fact that the type 
of the species was discovered in the Upper Devonian (Chemung Group) 
of New York, but all the British examples originate from a higher 
horizon.* 

Description or tHE Mrarnopr SPECIMENS. 
Archeosigillaria Vanuxemi (Goppert). 


The largest specimen I obtained measures 18cm. in length, the width of the 
branches being from 8 to. 10 mm._ It exhibits very clearly the dichotomous branching 
of the species, but owing to the branches being flattened by pressure and rather badly 


1 Journ. Linn. Soc., Botany, vol. xxi, p. 560, pl. xviii. 

. 2 Trans. Nat. Hist. Soc. Glasgow, N.s., vol. vi, p. 38. 
3 Gnou. Maa., 1906, p. 391, and Rep. Brit. Assoc. for 1906, p. 303. 
4 Journ. Linn. Soc., Botany, vol. xxi, p. 564. 


J. W. Jackson—Archwosigillaria in Westirorland. a9 


preserved, the leaf-scars are not shown to advantage. The slab containing this 
specimen also shows a cross section of a species of Syringopora, and contains several 
specimens of Svminula sp. On the back of the slab is a portion of a branch bearing 
the cone referred to previously, and I found on development that the branch continued 
through the stone to the other side, where faint traces of it were visible a little to one 
side ot the branches just described. The cone appears in section, the separation of 
the slab having passed through its central axis. Both halves exhibit very clearly 
a long peduncle coming off at right angles to the stem. This is clothed with 
acicular bracts for a distance of three-quarters of an inch, where traces of sporophylls, 
ending in long points, begin to appear. ‘lhe cone has a width of about half an inch, 
and measures 27 inches in length, including the peduncle, but has undoubtedly been 
much longer, as the top portion is missing. Owing to its bad state of preservation, 
no further details can be made out with certainty. 

On another fragment of limestone, a portion of a dichotomously divided stem 
occurs, which exhibits, fairly well, the characteristic hexagonal leaf-scars of the 
older branches of A. Vanuxemi. ‘These scars are rather longer than broad, and 
measure 4°56 mm. by 3mm., the width of the stem beme 9mm. No vascular 
cicatricule, however, can be made out. 

Bothrodendron sp. 


This consists of a flattened portion of a large stem, which has come out free from 
the matrix. It measures 55 inches in length, 24 to 3 inches in breadth, and is 
2 inches in thickness. The surface is a mere film of carbonaceous matter, on which 
leaf-scars are distinctly visible in several places. These scars are 7 mm. apart, 
disposed in rows 10 mm. apart, each row winding round the stem in the usual 
rapidly ascending manner. ‘The specimen is too badly preserved to be specifically 
identified. 

Topograpay and Guontocy or Muarnop Fetr. 

Meathop Fell, which lies about a mile and a half east of Grange- 
over-Sands, is an isolated exposure of Carboniferous Limestone, 
surrounded on all sides by alluvial flats and salt-marsh. It is a little 
more than a mile in length, and just over half a mile in breadth; 
its greatest height above sea-level is 179 feet. On its south-east side 
it is cut off, by the Kent Estuary, from the Arnside Beds, which come 
next in succession. ‘The exposure may be described as being made up 
of a series of beds of impure limestone, more or less dolomitic, 
separated at intervals by thin earthy bands. The limestone is 
extremely hard, compact in texture, and breaks with a conchoidal 
fracture. It has been much quarried for strong plain work, such 
as engine beds, foundations, etc., but is not suitable for sculpture. 
The general dip of the beds is at a very low angle, it being about 
8° §.E. 

Fossils are not numerous in species, but large masses of Syringopora, 
along with a few small Cyathophyllids, etc., occur weathered out 
in relief on the cliff face, especially at Meathop Fell end. The 
Syringopora appear to consist of two forms; in one case the corallites 
are very small, not more than 5%; of an inch in diameter, geniculated, 
and with fairly numerous connectors; in the other case the corallites 
are distinctly larger, closely set, and nossess a thick wrinkled epitheca ; 
connectors fairly numerous, walls of corallites rather thick; diameter 
about 1 line. his form agrees very closely with S. geniculata of 
Hdwards & Haime’s figs. 2 and 2a of plate xlvi.! 

Near the top of the Fell, an impure limestone band, several inches 
thick, occurs, which appears to be entirely made up of specimens 


1 A Monograph of the British Fossil Corals, 1852 (Pal. Soc.). 


80 J. W. Jackson—Archeosigillaria in Westmorland. 


of Seminula sp. (cf. ficotdea), nearly all of which have the two valves 
adherent. Many of the specimens, however, are much crushed and 
broken. Occasional examples of single valves may be found which 
exhibit their Athyrid characters remarkably well. On the weathered 
faces of this bed, very definite lines of stratification may be observed, 
alternating between the layers of shells. The only other species, 
so far, noticed in this band is a small fragment of an Athyris showing 
concentric lamellation. There is a possibility of some of the others 
being Athyris also, which have lost their outer layer and therefore 
resemble Seminula. In its general appearance this band bears 
a striking resemblance to a modern sea-beach, where shells are thrown 
up in hundreds ; and it may, in all probability, represent an old shore- 
line. The same form of Semznula also occurs scattered through the 
beds below the above-mentioned band. 

At the top of the Fell, at the Meathop Fell end, I obtained the 
following species: Spor ifer cf. furcatus, M‘Coy* (abundant), Reticularva 
aff. lineata (Martin) (rare), and one or two others too imperfect to 
identify with safety. Other species collected at various parts of the 
Fell are, Psammodus rugosus, Ag. (fragment of tooth), Huomphalus sp. 
(cast), Lenestella sp., Seminula (2? ambigua), and Produetus aff. cor- 
rugatus, M‘Coy. 

The plant bed is apparently not exposed at the southern end of the 
Fell, as I have never seen any traces of it here. Where it does crop 
out is some little distance to the north. Associated with the plant 
remains are some small Seminulas and a Syringopora of a small 
ramulose type, which does not appear to have received a name yet. 
In beds immediately above, masses of Syringopora occur in abundance, 
and where these beds crop out at the surface large specimens may be 
obtained beautifully weathered out and free from matrix. With 
regard to the species of Syringopora, Dr. Sibly, to whom I submitted 
specimens, has .no hesitation in calling it a small variety of 
S. geniculata, using that name merely as a group name, and adopting 
Edwards & ,Haime’s interpretation of the name. He says it is 
distinctly smaller than the S. ef. genteulata which abounds in D, of 
the South-West and the Midlands, but is of the same type. | 

It is perhaps premature to attempt to fix definitely the exact horizon 
of these beds, as they appear to have been, as yet, but superficially 
studied. 

As already mentioned in the North Wales exposure, 4. Vanucemi 
occurs in beds which are assigned to the S, subzone. In the Shap 
exposure, the exact horizon ‘and fossil associates of A. Vanuxemi 
are, unfortunately, not so well known. My friend Canon Crewdson, 
honorar y. curator of the Kendal Museum, tells me that the Shap 
Yoll-bar quarry (now closed), from which their specimens came,. is 
about 13 miles south of the village, He has since found the species. 
in an old quarry at the northern end of the village, but cannot 
remember seeing any other fossils associated with it. In his opinion 
the ‘ Vanuxemi Bed’ forms part of the Shap—Ravenstonedale Limestone, 
probably near the top. He has, however, seen no trace of 4. Vanuwemt 


1 This and several others were kindly identified by Dr. T. F. Sibly, F.G.S. 


Notices of Memoirs—Luminosity of Uranium. 81 


in the quarry at Shap summit, near the Granite works, which is said 
to be the same Limestone, though there are frequent vegetable Tempins 
(Stegmaria, etc.) in that quarry. 

Professor Garwood, in his provisional correlation of the Faunal 
Succession in the Carboniferous Limestone of these Northern exposures,* 
places the Meathop Fell Beds doubtfully im C,, and correlates them 
with similar dolomitic beds at Crag Mollet in the Brigsteer section. 
At the latter place a bed occurs at the base which is marked by clusters 
of Diphyphylium pseudo-vermiculare (M‘Coy). This same. form also 
occurs abundantly near the top of the Shap—Ravenstonedale Lime- 
stone, so that the beds containing A. Vanuxemi at Shap are, in all 
probability, equivalent to the ‘ Vanuxemi Beds’ at Meathop Fell. 

Professor Garwood further remarks on the possibility of the above 
Diphyphyllid Lithostrotion being considered typical of (S), in which 
case the Meathop Fell Beds, and others, would have to be included in 
S) also. 
=. discovery, therefore, of 4. Vanuxemi at Meathop Fell, coupled 
with its occurrence in beds of, presumably, the same age at Shap, may 
be helpful in arriving at a satisfactory conclusion as to the correct 
horizon of these beds, especially when the exact horizon of. the plant 
is known in the North Wales exposure. 

In conclusion, [ must express my indebtedness to Mr. J.T. Stobbs, 
F.G.8., and Dr. T. F. Sibly, F.G.S., ete., for their kindness in 
confirming the identification of several specimens, and to Dr. R. 
Kidston, F.R.S., etc., for kindly looking over the plant remains and 
giving me his opinion thereon. 


NOTICES OF MEMOTRS.- 


Nore on THE Spontaneous Luminosity oF A Uranium Muryerat.? 
By the Hon. R. J. Srrurr, M.A., F.R.S., Professor of Physics, 
Imperial College of Science, Stange, Kensington. 


UMOURS of luminosity having been observed in Cornish seeShnverea |, 

in the dark, are not infrequent. I have myself been told of 

such phenomena by rustics in the mining district, and more than one 
hoe has mentioned something similar. 

. F. W. Rudler® has quoted a remark by the late Mr. Garby 
ae specimens of uranite ‘‘ when first discovered by the miners in 
Huel Buller and Huel Basset were very phosphorescent, so much so 
that after the lights were extinguished many of the crystals might be 
discovered in situ’’,* and he has suggested that this may be in some 
way connected with the self-luminosity of radio-active bodies. The 
observation would seem to have been made by the miners, not by 
a scientific observer, and it is implied that the luminosity was of the 
nature of ordinary phosphorescence, and due to previous exposure 
to light. 


Gzou. Mac., 1907, p. 70. 

Proc. Roy. Soc., Series A, 1909, vol. Ixxxiii, p.. 70. (Abridged. 
Handbook to Minerals of the British Islands, ‘pub! ished by the Geological Survey. 
Trans. Roy. Geol. Soc. Cornwall, 1865, vol. vii, p. 86. 

DECADE V.—VOL. VII.—NO. It. 6 


eo WH 


82 Reriews— Geological Survey of Basingstoke. 


Recently examining a specimen of uranite (autunite), I was struck 
by its resemblance to the artificially prepared uranium salts, and it 
occurred to me that in all probability it would be found to exhibit the 
spontaneous luminosity observed in these by H. Becquerel,’ which is 
attributable to fluorescence of the substance under the action of its 
own radio-activity. Experiment confirmed this anticipation. The 
mineral is: easily perceived in a perfectly dark room by a well-rested 
eye. There is no difficulty in walking up to it from a distance and 
touching it, without any other guidance than the luminosity. Autunite 
is more luminous than uranium nitrate, but less so than potassium 
uranyl sulphate. 

This effect is quite independent of the previous exposure to light. 
Such exposure only leaves an afterglow in uranium salts of very 
short duration. It cannot be detected without the phosphoroscope. 

The specimens in which I have observed the luminosity are some 
recently raised in Portugal, which I owe to the kindness of Mr. A. de 
Vere Hunt. Old specimens from Cornwall and from Autun do not 
exhibit it. The loss of luminosity is connected with a loss of water of 
erystallization. This was established experimentally by sealing up 
a specimen in an exhausted glass tube with phosphoric anhydride. 
In a few hours the latter had deliquesced considerably, while the 
autunite had lost both its luminosity in the dark, and also the green 
fluorescent. shimmer which it had previously exhibited in daylight. 
Some uranium salts are known to be much more fluorescent than 
others, and there is nothing specially surprising in the fact that a loss 
of water is accompanied by a loss of brilliancy. 


RAV LEWwSs-. 


pois ee 
'J.—Geronogican Survey or Grear Brrrarw. 


Tus Grorocy or run Counrry around Bastnesroxn. By, Ee ad 
Ossorne Wauire, F.G.S. pp. v, 119, with 14 text-illustrations. 
1909. Price 2s. Colour-printed map, Sheet 284, 1s. 6d. 


LTHOUGH not officially connected with the Geological Survey, 
ue Mr. Osborne White has already rendered much service to the 
Institution in writing the Memoir on the Geology of Hungerford and 
Newbury, and in assisting with those on Andover, Henley-on-Thames, 
and Wallingford. He has now written the memoir to accompany 
Sheet 284 of the new series Geological Survey Map, which embraces 
an area concerning which we have hitherto had very little detailed 
information beyond that contained in previous official memoirs on 
more extensive tracts, by H. W. Bristow, W. Whitaker, and A. J. 
Jukes-Browne. The six-inch field-maps, showing the revised geology, 
with notes by the late J. H. Blake and Messrs. C. E. Hawkins and 
F. J. Bennett, were placed at the service of the author, 

The country under consideration is almost wholly in Hampshire, 
the northern part including a tract of the Eocene strata of the London 
Basin ; and the southern part consisting mainly of Chalk with a portion 


' Comptes Rendus, 1904, vol. 138, p. 184. 


Reviews— Geological Survey of Basingstoke. 83 


of the Upper Greensand inlier of Kingsclere on the west, and a portion 
of the Wealden area on the south-east. his latter tract, drained by 
the head-waters of the Wey, takes in less than a square mile of the 
parish of Farnham in Surrey. 

The lowest formation exposed is the Gault, and the Folkestone 
Beds of the Lower Greensand have probably been reached in a well 
in the Wey Valley. The Gault, no doubt, underlies the whole of the 
area, but nothing is known of the underground disposition of the 
strata beneath, nor of the depth to the Paleozoic floor. 

Particulars are given of the Gault, with the zone of Dowvilleiceras 
mammillatum at its base, and that of Hoplites interruptus above; and 
also of its fossils and phosphatic nodules. ‘he Upper Greensand, 
consisting largely of malmstone, siliceous and calcareous, belongs to 
the zone of Sch/loenbachia rostrata, and the highest beds adjoining the 
Chloritic Marl are locally impregnated with phosphatic matter. The 
phosphatic beds at the base of the Chalk, which contribute so much 
to the fertility of the soil on the Chloritic Marl, were described more 
than sixty years ago by Paine & Way, but the pits which yielded 
many fossils in the parishes of Bentley and Farnham have long been 
filled up and obliterated. The Chalk divisions range from the zone of 
Schloenbachia varians to that of Warsupites testudinarvus, and much new 
information is given regarding the strata and their fossils, including 
the sub-zone of Heteroceras reussianum and the Uintacrinus Band. 

Despite the great unconformity between Chalk and Reading Beds 
no evidence of disrordance has been observed in the district. The 
surface of the Chalk was even where the junction of the formations 
could be seen, but in two localities the perforations of some boring 
animal were seen on the Chalk floor. The author assigns to the 
Kveading Beds the blocks of greywether sandstone which occur here 
and there in the district. 

The London Clay, which extends over a considerable area, has 
yielded a good many fossils, and it attains a thickness of 385 feet near 
Odiham. The author remarks that it is probably not more than half 
that thickness in the north-western part of the district. Westwards, 
in the Andover country, the thickness of the London Clay has been 
estimated at from 60 to 100 feet, while south of Newbury it is about 
60 feet, and thence it diminishes further west and to the north. 

The Bagshot Series 1s described under the headings of Lower Bagshot 
Beds, Bracklesham Beds, and Upper Bagshot Beds—perhaps because 
this classification was adopted on the colour-printed map which, 
though issued in 1905, was based on the hand-coloured map of 1897. 
The grouping, therefore, differs from that adopted in the Andover 
Memoir of 1908, wherein the term Bagshot Beds is restricted to the 
Lower Bagshot Beds. The Upper Bagshot Sands of the London 
Basin are now usually grouped with the Barton Beds. 

There is an interesting chapter on the tectonic structure and drainage 
features, illustrated by a map showing the lines of anticline and 
syncline, while the author points out the relations of the streams to 
the geological structure. 

The Plateau gravels are regarded as of fluviatile origin, and as 
“remnants of old alluvial flats or flood-plains, developed during 


84 Reviews—Geology of Bodmin and St. Austell. 


pauses in the downward displacement of the local limit of subacrial 
degradation ’’. 

The Clay-with-flints, the Valley gravels, and Alluvial deposits are 
duly described, and there is an excellent chapter on Economic Geology. 

The Memoir throughout bears evidence of much diligent research, 
and adds largely to our knowledge. The author, moreover, has 
earefully studied the works of other geologists, and does full justice 
to their labours. The only misprint we notice is H. W. Fitton for 
We He Bitton. 


I1.—Tuae Groroay oF tHE Country Around Bopmin AnD Sr. AUSTELL. 
By W. A. E. Ussurer, G. Barrow, and D. A. MacAnisrrr, with 
Notes on the Petrology of the Igneous Rocks by Dr. J. 8. Frerr. 
8vo; pp. vi, 201, with 3 plates and 34 text-illustrations. London, 
1909. Price 4s. 

fWVHIS Memoir is descriptive of the one-inch colour-printed map. 

Sheet 347, which takes in the area from Bodmin on the north 
to the coast at Fowey and St. Austell Bay on the south. The greater 
portion of this country is occupied by Lower Devonian rocks and the 
bold granite mass of St. Austell and Hensbarrow, with a tract of 

Middle Devonian slates on the north-east. The oldest Devonian 

rocks, grouped as Dartmouth Slates, contain fish-remains of Lower 

Old Red Sandstone type, and the rocks appear in an anticline along 

the eastern coast to the north of Fowey, and thence extend to near 

Lostwithiel. They are bordered by the Meadfoot Beds, beyond which 

are the Staddon and Grampound Grits. ‘The coloration of the map. 

suggests that the Staddon Grit on the north and the Grampound 

Grit on the south are equivalent strata on the opposite sides of the 

anticline. This view is supported by Mr. C. Reid, but is not accepted 

by Mr. Ussher, who regards the Grampound Grit Series as representing 
the marginal conditions of lower beds in the Meadfoot Group, perhaps 
equivalent to the Looe Grits. The Meadfoot Beds have yielded 

a number of fossils, but so poorly preserved that most of the species 

and many of the genera collected by the Geological Survey are 

doubtfully identified. Fossils throw no light on the disputed 
succession, as none are recorded from the Grampound or Staddon Grits. 

The Middle Devonian slates are stated to be fossiliferous, though 
“it is very seldom that anything but crimoid markings can be 
distinguished ”’. 

The region therefrom is not one to attract the student of Devonian 
paleontology; but a great step in advance over the older map has 
been made in the insertion of the geological subdivisions now 
depicted, while the long experience gained by Mr. Ussher has enabled 
him to correlate them with the subdivisions which he has traced step. 
by step from Eastern Devonshire. 

The granite areas have been mapped out in much more detail than 
in the original geological survey map, and the metamorphic aureole in 
the bordering Devonian rocks, described mainly by Mr. Barrow and _ 
Dr. Flett, has been more definitely indicated. Dr. Flett has dealt 
generally with the pneumatolytic alteration of the granite, observing 
that the changes produced by vapours passing through the rock, after 


Reviews—German South Polar Expedition. 85 


its consolidation, are of three sorts: (1) tourmalinization, as exemplified 
in luxulyanite and in the schorl-rock of Roche; (2) greisening, as seen 
at Criggan; and (3) kaolinization. The kaolinization or alteration of 
eranite to china-stone and china-clay is a subject discussed by 
Mr. MacAlister, supplemented by observations made by Dr. Flett. 
With regard to the kaolinization, Mr. MacAlister refers to the agency 
of magmatic waters containing carbon dioxide in solution and fluoride 
vapours. Dr. Flett remarks that the facts ‘‘ point to the probability 
that neither fluoric nor boric gases were the chief agencies of 
kaolinisation, and support Vogt’s hypothesis that carbonic acid was 
the principal, though probably not the only, gas involved’’. Many 
interesting particulars are given of the china-stone and china-clay, but 
it has not been found possible to mark on the map the areas over 
which they are exposed. Economic geology, indeed, receives ample 
treatment. ‘The chapter on mining, prepared by Mr. MacAlister, 
with numerous illustrative sections, contains full information of the 
workings for tin and copper ores, as well as silver-lead ores, red and 
brown hematites (for which Restormel was once famous), manganese 
ore, gold, uranium ore, etc. Of road-metals, the harder diabases and 
the calc-flintas (altered calcareous sediments in the Meadfoot Beds) 
are reckoned more durable than the elvans. 

Mr. Barrow has described some of the physical features and the 
indications he has found of the old Pliocene platform at about 430 feet 
above sea-level. There on flat moors, beneath peat, rainwash, and 
head, occur ferruginous gravels that have been worked for stream- 
tin, and these may possibly be of Pliocene age. The later Pleistocene 
and Recent deposits are described in detail, evidently by Mr. Ussher, 
but curiously enough his initials, appended to many paragraphs, have 
been omitted from this section as well as from the important chapters 
on the Devonian rocks. This is much to be regretted. 


Ii1.—Tuar Geruan Sourn Potar Exprprrion, 1901-1908. Vol. II, 
Heft V: Geography and Geology. pp. 63 and 3 plates. . Berlin, 
1909. Price 10 marks (8 marks to subscribers). . 

(Devrscue SupPoLaR-ExPEDITION, 1901-1903, im Auftrage des Innern 
herausgegeben von E. von Dryeatsxr, Leiter der Expedition. 
Il Bd. Geographie und Geologie, Heft V.) 


f{\HE present report is composed of four sections, dealing mainly with 

the islands of St. Paul and New Amsterdam in the Indian Ocean. 
The geography is dealt with by E. von Drygalski, the leader of the 
expedition, the geology by E. Philippi, the character of the rocks by 
R. Reinisch, and the plants and animals by E. Vanhoffen. According 
to Dr. von Drygalski, the islands of St. Paul and New Amsterdam are 
both volcanic and rest upon a common tapering base, which rises from 
about 8000 metres below sea-level. At a depth of 1500 metres this 
common source divides into two cones, which form the two islands. 
Both islands have a number of parasitic cones, but these do not 
constitute so striking a feature in the case of St. Paul as in New 
Amsterdam. The islands of Kerguelen and Heard on the one hand, 
and St. Paul and New Amsterdam on the other, also have a common 


86 Reviews—German South Polar Expedition. 


base, which rises above the surrounding Kerguelen Plateau. When 
St. Paul, in particular, is considered it is found that the imner part of 
the crater 1s connected with the outer sea by reason of the submergence 
of the north-easterly part of the island along a 8.E.—N.W. line. The 
salinity of the water within the crater basin is almost identical with 
that of the surrounding sea, while within the crater itself this salt- 
percentage, as well as the temperature of the water, remains constant 
for the whole depth. According to Vélain, a former explorer, the 
amount of carbon dioxide in the crater water increases with the depth. 
He derives the gas from the exhalation of CO, and N from the 
ground of the basin. Such an exhalation would also materially 
affect the distribution of the organic life. Former investigators have 
reported that the water temperature at the mar gin of the basin locally 
exceeded that of the inner portion by 4° or 5°, but this has been 
found by the present explorers to be not the case. Practically the 
same temperature prevails on the margin as in the middle. From 
this, as well as from other evidence of a negative kind, the absence of 
hot springs might be inferred. As the distance apart of the positions 
where the temperatures were taken is, however, about 400 metres, the 
existence of such springs is not an impossibility. Both islands have 
very steep coasts, the coast being highest on the west, where, on 
account of the stronger westerly winds, the waye action is heaviest. 
The deepest parasitic craters of St. Paul are on the south and west 
cape. They are already partly cut through by the sea, as shown by 
the charts of Vélain and von Hochstetter. Such a phenomenon shows 
the great influence of the wave action, since the chief crater itself, 
according to von Hochstetter, is not very old, and the parasitic craters 
are quite young. In view of the morphological and climatic conditions 
the only possibility of anchoring for the purpose of landing on either 
of the two islands is on the north-east side. It appears that human 
habitation would suffer from the poor water supply, and St. Paul, in 
particular, would be less advantageous, because of the absence of 
wood. An attempt was made, through a previous expedition (that 
of the ‘‘ Novara’), to start wood-growing, but the result has been 
disappointing. The fishermen have successfully g grown potatoes, wheat, 
maize, and barley, and other grain also appear to grow well. Both 
islands might thus be possibly used as settlements, yet the unfavour- 
able climate and the absence of firewood would be great hindrances. 
The chief value of the islands lies in their wealth in fish. 

In the geological section Dr. Philippi gives, as in the foregoing 
section, an historical account of the works of previous investigators 
as far as they bore on geology. Among these writers Vélain and 
von Hochstetter are to be “particularly mentioned. Dr. Philippi differs 
from the older explorers in regard to the last period of eruption and 
the origin of the present crater of St. Paul. In agreement with 
von Hochstetter, he would consider the crater-opening to have been 
formerly much smaller and higher than the present central crater ; 
but Dr. Philippi thinks that this older vanished central crater of the 
basaltic period did not lie at the middle, but near the margin of 
the present crater basin. Although, as stated by von Hochstetter, 
the present crater is a product of a very late time, and was certainly 


Reviews—German South Polar Expedition. 87 


not in existence in its present form during the basaltic eruptive 
period, yet it is believed that the shape of the present crater is to be 
explained through an explosive outburst rather than subsidence. As 
regards the lavas and tuffs of St. Paul, it is impossible to speak of 
the period of their origin with certainty, because of the absence of 
any tossil-bearing sediments. Probably a part of the eruptive period 
belongs to Tertiary, another to Quaternary and later times. It 
is impossible, however, to know where the Tertiary portion ends 
and the other begins. An examination of the Dumas crater of New 
Amsterdam revealed evidences sufficient to support Vélain’s results im 
all essential details. The crater cone and the lava streams which ran 
from it have quite a fresh appearance ; the eruptions were undoubtedly 
still in progress during historical times. The late period of eruption 
of the lava streams accounts for the favourable landing facilities near 
the Dumas crater, for the wave action has not had time to cut a steep 
wall in the lava. Lateritic weathering products, which play such an 
important part on the island of St. Paul, are absent. This fact also 
speaks for the recency of eruption in the Dumas crater. . In some 
parts of the lava, cavities, often 8 to 10 metres broad, twice the ‘same 
measurement in height, and over 200 metres long, were met with. 
From the roofs of these caves hang lava stalactites of fantastic shapes. 
According to Vélain the cavities are due to gases which collected under 
the lava stream and afterwards forced their way through it. The 
present-day vulcanologist generally explains such a phenomenon as 
the result of the coating of the upper layer of the lava stream by a non- 
yielding outer crust; the inner portion of the stream, moving forwards, 
would leave behind a hollow cavity. Some of the cavities observed 
by the present expedition were undoubtedly the result of gaseous 
accumulation. 

Dr. Reinisch discusses the chemical relationship of the basalts of 
St. Paul, New Amsterdam, Kerguelen, Heard, and Possession Islands. 
Rhyolite tuff, basalts, and siliceous sinter are found on St. Paul; only 
basalts of various constitution are known on New Amsterdam, basalts, 
phonolite, and trachyte on Kerguelen, and basalts on Heard and 
Possession Islands. Very instructive tables and diagrammatic pro- 
portional representations of the chemical constituents of the rocks are 
given. 

Dr. Vanhoffen treats of the plants and animals of St. ‘Paul and 
New Amsterdam in an exhaustive manner. A comparison of the 
faunal lists of the two islands shows a certain agreement. This 
agreement would probably be found on closer investigation to be still 
greater than appears at present. It is also seen that the number 
of peculiar forms is few and that no close relationship exists with the 
animal life of the neighbouring sub-Antarctic islands. Hence it is 
inferred that the fauna is an accidental and not an original. one, and 
that it has been affected by human interference. 

The report is illustrated by three plates of eight photographie views 
and several text-illustrations. 

Ivor THomas. 


88 Reviews—Transactions of New Zealand Institute. 


IV.—Arms in Pracrican Grotocy. By Professor Grenvinte A. J. 
Cote. .: Sixth edition. 8vo; pp. xvi, 431, with 2 plates and 
136. text-illustrations. London: Charles Griffin & Co., 1909. 
Price 10s. 6d. 

FYWVHAT a geological handbook should pass through six editions in the 

course of eight years is the most satisfactory testimony to its 

merits, and we heartily congratulate the author on the well-deserved 
success of his work. ‘The volume has remained of the same dimensions 
since we noticed the issue of the fourth edition in 1902, but it has 
undergone sundry revisions and alterations needful to bring the 
subject-matter up to date. As a companion and practical guide to 
geology''the work is excellent. In the preliminary chapters the 
student will learn how to equip himself for field observations and the 
collection of specimens, while the main portions of the volume give 
precise and abundant information on the modes ot examination and 
determination of minerals, and of rocks, sedimentary, igneous, and 
metamorphic. The final part deals with the examination of fossils, so 
far as ‘the invertebrata are concerned, and the author has rightly 
endeavoured to keep the limits of the genera as wide as possible. 

Thus we are glad to see such a name as Rhynchonella spinosa 

perpetuated in place of the modern subdivisions of the genus, which 

are useful only to a palseo-zoologist. 


V.—Trawnsactrions or tHE New Zeatanp Insrirure, vol. xl, for 
7 1908, issued June, 1909. 
le an article on ‘‘ The Geology of the Quartz Veins of the Otago 
Goldfields”, Mr. A. M. Finlayson points out that these veins 
would suffice to account for the alluvial gold, and that no other source, 
such as had been suggested with reference to the schists, supplied any 
appreciable quantity. 

Dr. P. Marshall describes a nephelinitoid phonolite from Rarotonga, 
and a similar rock has been found near Signal Hill, Dunedin, by 
Mr. C.:A. Cotton, who gives an account of other varieties of phonolite 
from that district. Mr. R. Speight records the occurrence of a horn- 
blende-andesite in the Solander Islands. Dr. Marshall describes some 
new species. of fossil Cephalopods from strata im the neighbourhood of 
Mandeville and Kawhia Harbour. ‘hey include Broncoceras, Ortho- 
ceras, Arcestes, Phylloceras, and Avgoceras. Among other fossils are 
Ostrea, Gryphea, Trigonia, Ialobia, and Spirvferina. Dr. Marshall 
remarks :.‘‘ Since several of these are not known in strata older than 
the Jurassic, it is probably right to class these strata as Jurassic, 
thereby ignoring the presence of the archaic genera here mentioned. 
This conclusion seems all the more reasonable when the present isolated 
position of the Dominion is considered. It is quite possible that 
another ‘period of isolation had terminated at the beginning of the 
Jurassic period. An old fauna which had lived on during the period 
of isolation would then be mingled with the invading newer and more 
vigorous types. Such an explanation might reasonably account for 
the rapid change in life-forms which has caused Sir James Hector to 
class a conformable series of rocks as of an age extending from Permian 
to Jurassic.” 


Reviews—Geological Survey of Western Austraha. 89 


V1I.—Geuotoercat Survey or Western AvsTratia. 
ULLETIN No. 35 (1909) consists of a well-illustrated report on 
the Gold and Copper Deposits of the Phillips River Goldfield, 
by Mr. Harry P. Woodward, with notes on the crystalline rocks by 
Messrs. E. 8. Simpson and L. Glauert. The district les near the 
south coast, with a port about 150 miles east of Albany, and in 
geological structure it is a complex of schists and serpentines, granites 
and areenstones, together with some probably Tertiary sandstones, 
quartzites, and conglomerates, and various superficial deposits. The 
crystalline rocks are much decomposed, in places to a depth of nearly 
100 feet, and the lodes, with few exceptions, have at present been 
worked only above the ground water-level. The lodes comprise 
(1) basic cupriferous dykes, and (2) siliceous and ferruginous deposits, 
which appear to fill channels along rock-joints. The conclusions 
drawn are that the cupriferous dykes are of sufficient size to warrant 
deep mining, but that gold and silver will then occur in negligible 
quantities. The siliceous and ferruginous deposits give less promise 
of permanency, but they usually carry fairly high gold and silver 
values, and have been classed as auriferous lodes, copper, when 
present, being in small quantities. In some instances, however, with 
increasing depth, the gold is greatly diminished, and copper ore 
becomes dominant. It is noted that primary sulphides occur in the 
rocks above the ground water-level, and the explanation given is 
that the great density and impermeable character of the matrix have 
protected the ore, in these cases, from the oxidizing influence of 
descending aerated water. The ores worked during the past eight 
years have yielded on an average 4 per cent. of copper and half an 

ounce to the ton of gold. 


VII.—ScutucHTen AUF DEM Pema Tscuoxusu. By, ALEXANDER 
Iwrscuenxo (of Kiev). {The Ravines of the Tschokusu Plateau. | 
Ann. géol. ef minéral. de la Russie, Novo-Aleksandria, vol. xii, 
livr. 1-11, pp. 19-26. 

FJ\HIS paper sets forth the results of the investigations carried out 

by the author during a second excursion to the southern portion 
of the Tschokusu Plateau in the summer of 1908. ‘The district is eut 
out into terraces, the southern margins of which are broken into by 
ravines. These ravines widen considerably, and often form cauldron- 
shaped expansions in their upper reaches ( Oberldufe), while the lower 
reaches become narrower. ‘The terraces undoubtedly represent the 
results of the drying-up of the Aral basin. Their relative size and 
slope point to intermittent recession of the sea, the periods of non- 
recession corresponding to the time when the terraces were formed. 

The ravines were formed contemporaneously with the recession of the 

sea, the upper reaches having originated at an earlier period than 

the narrower lower reaches. From the nature of the denudation the 

T'schokusu Plateau belongs to the same category as the district of 

Barsukow ; both are characterized by desert conditions. 

The article is accompanied by three photographs and two diagram- 


matic illustrations. 
d (rgd 


90 Reviews—Guide to Chatk Fossils. 


VIII.—A New Pocxrr-Guive ro Cuark Fossits. Kart WANDERER. 
Diz wicuriesreN TIERVERSTEINERUNGEN AUS DER KREIDE DES | 
Koyiereicnres Sacusen. 8vo; pp. xxii, 80, with 12 plates in 4to 
(folded), and 11 figures in the text. Jena, 1909. Price 3 marks. 


(FVHE plan of this little book is excellent. It provides a tabular 

view of the Chalk of Saxony, a bibliography, a list of places 
where fossils can be obtained, and devotes its eighty pages to short 
descriptions of the fossils, commencing with the Foraminifera and 
ending with the Vertebrata, completing the whole with an alphabetical 
index to the fossils. The text-figures are explanatory diagrams of the 
structural features of regular and irregular Echinoderms, Brachiopods, 
Pelecypods, Gasteropods, and Cephalopods, and the plates provide 
sufficiently good figures of all the fossils described in the text. The 
book is cut to a convenient size for the pocket, and provides the 
worker in the field with a handy means of readily identifying 
the bulk of his finds on the spot. The English collector will find 
this book of considerable value for his own purposes. R 


“C.D: 


IX.—Tup Orv Derosrrs or Sourn Arrica. Part I: Base Metals 
(1908). Part IL: The Witwatersrand and Pilgrimsrest Goldfields 
and similar occurrences. By T. P. Jounson. London: Crosby 
Lockwood & Son, 1909. Price 5s. net each. 


f lie two small volumes are intended for the use of those 
technically connected with the mining industry and as a guide. 
to the prospector. 

In a country of such diversified geological structure as South Africa 
it is difficult to gauge the wants of those interested in the development 
of its mineral resources; but it may be as well, and sufficient, to state 
that the author ignores the stratigraphy of the country, since, in his 
opinion, the ‘‘ principles of ore deposition” are independent of it. 

Considering the high price and small size of these volumes we 
should have expected to find more original subject-matter, more 
carefully prepared maps and sections, and a greater economy of space 
both in the arrangement of the text and of the sections. 


X.—Brier Novices. 


1. JouknaL oF Grotocy (Cuicaco).—In this Journal for October— 
November, 1909, there is an interesting article on the ‘ Physical 
Geography of the Pleistocene, with special reference to Pleistocene 
Conditions”’, by Mr. R. D. Salisbury. He refers to evidence of greater 
depression during the glacial epochs than during the interglacial ; 
also to the effect of increase of altitude on climate, leading to greater 
erosion and to the greater consumption of carbon dioxide whereby the 
temperature became lowered. Decay of rocks was checked by decrease 
of altitude or temperature, or by the accumulation of ice-sheets which 
protected the rock beneath from ready carbonation. The author refers. 
also to the loading of the land-surface with ice over vast areas, to the 
consequent effect on crustal movement, and to the recurrent processes: 


Brief Notices, 91 


of erosion and sedimentation by ice agencies. Finally he deals briefly 
_with changes in life, which apart from mammals have been insigni- 
ficant, observing that even among mammals it is not clear that the 
dying-out of species in one locality was contemporaneous with the 
disappearance of the same species in other localities. 

Mr. Stuart Weller contributes the ‘‘ Description of a Permian 
Crinoid Fauna from Texas”, and Mr. 8. W. Williston gives an account 
of ‘* New or little-known Permian Vertebrates”’, with the description 
of a new genus of amphibian, named Zrematops Miller. 


2. Puiriprins Istanps.—Dr. Warren D. Smith has issued a report 
on Lhe Mineral Resources of the Philippine Islands (Bureau of Science, 
Manila, 1909). He regards the future results of mining as promising. 
The gold production from lodes, decomposed rocks, and placer deposits 
rose in value from about £20,000 in 1907 to £50,000 in 1908. Coal, 
worked on Batan Island, amounts to 130 tonsa day. ‘There is a good 
deal of ironzore, but at present there is only one furnace in operation, 
and this is owned and worked by a Filipina woman. Limestone 
and shale suitable for cement occur; and there are indications of 
petroleum, kaolin, manganese ore, and copper. Artesian water has 
been obtained in the great plain of Luzon. 


3. GuotocicaL Survey or Canapa.—Among publications issued in 
1909 by, the Canadian Department of Mines, we have received a report 
by Mr. D. B. Dowling on Zhe Coal-fields of Manitoba, Saskatchewan, 
Alberta, and Eastern British Columbia. The coal is found on three 
‘4listinct horizons in the Cretaceous, separated by shales of marine origin. 
The lowest horizon is at the base of the system, and is considered to 
be Cretaceous from its flora. It lies just above the Fernie Shale, 
which is regarded as Jurassic. ‘The coals include anthracite, 
bituminous coal, and lignite, and the author estimates that there 
is a total quantity of more than 143 thousand million tons in the 
provinces described. 

In another report Mr. R. G. McConnell describes ‘‘ The Whitehorse 
Copper Belt, Yukon Territory”. The belt, as at present determined, 
extends for a distance of about 12 miles, and the principal ore bodies 
occur in limestone adjoining granite. The important economic 
minerals are the copper sulphides, bornite, and chalcopyrite ; and they 
are associated in some cases with magnetite and hematite, in other 
cases with garnet, augite, and tremolite. : 

We have also received a useful Catalogue of Publications of the 
Geological Survey, Canada, revised to January 1, 1909. 


4. Mining Macazine.—We have received a copy of the Dhning 
Magazine for November, 1909, being No. 3 of vol.i. Although it deals 
essentially with the practical applications of geology, with mining 
and metallurgy, with companies, investments and speculations, and 
with problems of labour, it also contains reviews of books, and many 
miscellaneous paragraphs of scientifie as well as economic interest. 
Some remarks are made on the British Radium Corporation, formed to 
work the pitchblende in the Trenwith Mine in Cornwall, and doubt is 
expressed whether it is a sound commercial undertaking. 


92 Reports and Proceedings—Geological Society of London. 


There is an article by Mr. T. T. Read on ‘‘Coal Mining in 
Manchuria”’. The Fushun Mines, north-east of Mukden, are worked 
in Tertiary strata, which yield a soft bituminous coal. The total 
thickness of coal varies from about 150 to 270 feet, made up apparently 
of many seams closely associated. ‘The greatest thickness without 
a parting is, 32 feet, but the five seams worked are each from 9 to 
12 feet thick. It is estimated that the production for 1909 may be 
- about 700,000 tons. Apparently the coal was worked in very early 
times for the manufacture of pottery, as in making excavations on the 
ground large quantities of ancient Korean pottery and coins dating 
back to 800 B.c. have been discovered. 


5. Grotocy oF Brisror.—A concise and interesting Sketch of the 
Geological History of the Bristol District, by Professors C. Lloyd 
Morgan and 8. H. Reynolds, has been published by the Bristol 
Naturalists’ Society (Proceedings, vol. ii, pt. ii, 1909). It contains 
references to the principal published works, and embodies accounts of 
the more recent researches on the Silurian rocks, the Carboniferous 
zones, and the origin of the physical features. 


6. GerotocicaL Survey or New Jersry.—The Annual Report of 
the State Geologist, Mr. H. B. Kiimmel, for the year 1908 (1909), 
contains an account of the zine mines of Sussex County, by Mr. A. C. 
Spencer. The ore minerals are principally franklinite, containing 
oxides of iron, manganese, and zinc; willemite, silicate of zinc, much 
of it containing manganese; and zincite, oxide of zine, also with 
manganese. Mr. J. V. Lewis contributes a report on the Building 
Stones, illustrated with map, views of old and new buildings, and 
coloured plates of various granites, serpentine, marble, and other rocks. 


7. Georocican Lireratcre ADDED To THE GxEoLoGIcAL Socrery’s 
LIBRARY DURING THE YEAR ENDED DecemBer, 1908. 8vo. London 
(Geol. Soc.), November, 1909. Price 2s.—It is merely necessary to 
remind our readers that this valuable record of the geological work 
of the world is published for 19068. Mr. W. Rupert Jones, 
Mr. Belinfante, and Mr. C. H. Black have all contributed to the 
heavy task of getting it ready, and the publication fully maintains its 
position as the one indispensable work of reference for all geologists. 
An index of 76 pages to 113 pages of bibliography sufficiently 
indicates the exhaustive nature of the work and its utility. 


APP ORs AINa® OCG Bs» -NGsS-_ 


GrotocicaL Socrery or Lonpon. 
December 15, 1909.—Professor W. J. Sollas, LL.D., Se.D., F.R.S., 
President, in the Chair, 

The following communications were read :— 

1. “The Skiddaw Granite and its Metamorphism.”’ By Robert 
Heron Rastall, M.A., F.G.S. 

‘he visible exposures of the Skiddaw Granite are three in number, 
all very similar; part of the more northerly one is a greisen, which 


Reports and Proceedings— Geological Society of London. 98 


is not here dealt with. The normal granite is more or less por- 
phyritic in structure, with large phenocrysts of perthite, in a coarse 
or fine-textured ground-mass of orthoclase, plagioclase, biotite, and 
muscovite. Various micrographic intergrowths occur, indicating in 
some cases eutectics of three or more components. No reliable analyses 
are available, but the rock is provisionally classed as an alkali-granite 
of Hatch’s classification. 

Evidence is brought forward to indicate that the granite is intruded 
along the axis of an anticline, with a strike approximately E. 15° N. 
and W. 15° S., the normal direction for the district. 

The metamorphic aureole is very large, measuring about 6 miles 
from east to west and 5 miles from north to south. This is out of all 
proportion to the size of the visible exposures of granite, and it is 
inferred that the intrusion underlies a large area at a small depth. 

Within this area three distinct rock-types can be recognized, namely, 
(1) black slates, (2) grey flags, (3) grey grits. The metamorphism 
produced in each of these is described in detail, and it is shown that 
the commonly accepted zones of alteration do not hold, since the rocks 
concerned were originally of very different character. ‘The frequently 
described section in the Glenderaterra Valley runs across the strike, 
and includes both black slates and grey flags. The former never 
undergo a high degree of metamorphism, chiastolite being the 
characteristic mineral. The well-known cordierite-mica rocks of 
Sinen Gill are derived from the grey flags, and a very narrow zone 
close to the granite shows garnet and staurolite. The impure grey 
erits of the central band contain cordierite, andalusite, and mica, and 
garnets are only seen close to the contact with the Grainsgill greisen. 
The Carrock Fell intrusion produces little or no alteration in the 
grits, with which it comes into contact for a long distance. 

The phenomena here displayed may be summed up as an example 
of a moderate degree of thermal metamorphism, due to the intrusion 
of a large mass of granite, at a comparatively low temperature, into 
a series of rocks of variable composition, which had previously under- 
gone dynamic metamorphism. The most important minerals produced 
are cordierite, andalusite and chiastolite, biotite and muscovite, while 
garnet and staurolite are only found close to the granite. Owing to 
the variations of lithological composition across the strike, 1t has not 
been found practicable to divide the aureole into concentric zones, but 
the alteration is gradual and progressive towards the intrusion. 


2. ‘The Metallogeny of the British Isles.” By Alexander Moncrieff 
Finlayson, M.Sc., A.O.S8.M., F.G.S. 

The ore-deposits of the British Isles (tin, copper, lead, zine, gold) 
are considered synthetically in their relation to igneous rocks and to 
tectonics. The four major epochs of igneous activity and crust- 
movement in the area were: pre-Cambrian, post-Silurian (Caledonian), 
post-Carboniferous (Hercynian), and Tertiary. A few insignificant 
ore-occurrences, including the stanniferous magnetite in the older 
granite-gneiss of Ross-shire, date from the pre-Cambrian. A group 
of pyritic fahlbands in the Highlands of Scotland, and the wolfram- 
bearing pegmatites of the Grainsgill greisen, date from the Caledonian, 


94 Reports and Proccedings— Geological Society of London. 


accompanying the widespread province of Caledonian granites. The 
great bulk of “the deposits of economic importance, including the veins 
of Cornwall and Devon, the lead, zinc, and copper veins in England, 
Southern Scotland, Wales, and Treland, are of Hercynian (and 
Armorican) age. ‘This is shown by the age of the fissuring in many 
cases (post- Carboniferous to pre-Triassic), by the absence of ore-veing 
in Jurassic or later formations, and by other evidence. ‘The Tertiary 
voleanic period was not accompanied by ore-deposition, the evidence 
which has been adduced in favour of this in the Isle of Man, Cornwall, 
and Devon, and the North of England, being unsatisfactory. 

The ore-deposits are classified in accordance with the above- 
mentioned metallogenetic epochs, and are divided into metallogenetic 
provinces, as has been done by Professor L. de Launay with the ore- 
deposits of Italy, Africa, and Siberia. The essential features of the 
ditferent groups are summed up. The evidence, collected = sifted, 
indicates the following zones of ore-deposition :— 

(1) Pneumatolytic zone: tin, passing up into copper. 
(2) Deeper vein-zone: copper with gold. Lead and zine subordinate. 
(3) Middle and upper vem-zones : lead and zine. Copper subordinate. 

The conclusions drawn from the investigations are :— 

(i) The importance of the physical conditions of the Permo-Trias in 
favouring ore-deposition in upper zones. 

(ii) The close connexion between metallogenetic and petrographical 
provinces, and the essential dependence of ore-tormation throughout 
geological time on the differentiation of igneous rocks accompanying 
ereat crustal movements. Differences in ore-deposits in different 
localities and regions appear to be due to primary differentiation of 
ores accompanying the differentiation of igneous magmas at successive 
epochs. 


. “The Geological Structure of Southern Rhodesia.” By Frederic 
Philip Mennell, F.G.S. 


The author describes in some detail a portion of what may be 
termed ‘the Laurentian Area’ of Africa. The oldest rocks include 
all lithological varieties, and exhibit most of the known types of 
alteration. They comprise a great development of hornblendic rocks 
(epidiorites and amphibolites); on the other hand mica-schists, and 
sheared rocks generally, are conspicuously absent. They include 
(1) ‘basement schists’ on which the altered sediments were laid 
down, and (2) altered basic igneous intrusions, simulating rocks of 
any previous age. All these are older than the granites “by which 
they, and the metamorphic series, are invaded. 

The vertically bedded ‘ironstone series’ is described, and is com- 
pared with similar rocks of the Lake Superior region. They are 
shown to be especially developed along the eastern border of 
Matabeleland, and their conspicuous banding is attributed to re- 
erystallization of fine mechanical sediments under pressure. 

The conglomerate beds (or Rhodesian ‘ Banket’) are 10,000 feet 
thick, and rest unconformably upon the ironstone series in the west, 
both these formations being gold-bearing. But they overlap also 
elsewhere on to the ‘ basement series’; while they are represented 


Correspondence—B. Hobson. 95 


apparently in North Mashonaland by a thick series of grits, resembling 
microscopically the Moine Gneisses of the Scottish Highlands. The 
series contains pebbles of granite free from microcline, and banded 
ironstones. 

The thick crystalline limestones overlying the conglomerate series 
contain chert and dolomite, the latter rock occurring also as ait 
alteration product from serpentine. Graphite also is found, and is 
attributed to the insolubility of carbonaceous matter in a highly 
siliceous magma. Contact alterations of the limestones by the granites 
are described. 

The granites occupy the greater part of the area dealt with, and 
their intrusive character as regards the metamorphic rocks is shown. 
The normal granites are biotite-bearing, and have microcline as the 
dominant felspar; they never contain hornblende or muscovite. 
Patches of micropegmatite are included in the microcline, proving that 
the ‘ eutectic’ was not the final residuum of crystallization. Orthite, 
as well as epidote, occur in most sections cut from the Matopo 
Granite, and the author compares the mixed rocks of the gneissose 
edges of the granite with the ‘Fundamental Gneiss’ of Canada and 
other regions. 

The sedimentary series is subdivided as follows :— 


Zambesi Basin. Thickness in feet. 
Taba’s Induna Series . : : é 3 : ° = 200 
Forest Sandstones and Basalts : : : : ; - 1000 
Escarpment Grits . . 5 : 2 ; : 5 . 400 
Upper Matobola Beds (coal-bearing) F : : : a 300 
Busé Beds (local only ?) Naley- ‘ : : : 22 300 
Lower Matobola Beds (coal-bearing) : ; : 3 - 200 
Sijarira Series . ‘ away : : : : . 2000 


Limpopo Basin. 
Tuli Lavas. 
Coal Beds. 
Unconformity. 
Samkoto Sandstones. 


No fossils are recorded, other than silicified wood, except in the ~ 
coal-bearing beds, in which occurs Paleomutela Keyserlingi of the 
Russian Permian, as also plants. 

Various igneous rocks are described, including the great mass of 
picrite extending nearly across Rhodesia, which the author considers ° 
to be intrusive along a thrust-plane. 

The paper concludes with a description of the diamond-bearing beds 
of Rhodesia, which resemble those of Kimberley, and also contain 
fragments of eclogite. 


CORRESPONDENCE. 


= 


THE PRICE OF GEOLOGICAL SURVEY MAPS. 


Sir,— A recent decision of the Treasury, that the prices charged for 
all Government publications should be sufficient to cover the cost of 
their production, is calculated to discourage the pursuit of science and 


96 Miscellaneous. 


to prevent the spread of knowledge obtained at great cost. One result 
of this decision is that the price of almost all the hand-coloured 
Geological Survey Maps (the vast majority of those published) has been 
raised, in some cases preposterously ; for instance, quarter-sheet 92 N.E., 
Pateley Bridge, is raised in price from 3s. to 14s. 3d., quarter-sheet 
81 S.E., Buxton, from 3s. to 8s. 3d. This means that while thousands 
of pounds are spent in geological surveying the results are inaccessible 
to the public except at an almost prohibitive price. It makes 
British geologists envy their friends in the United States, where the 
antediluvian hand-colouring is unknown, and a geological folio 
containing topographical geological economics, and structural map 
with explanation, can be bought for 25 cents (1s.). In Canada 
geological survey maps are supplied gratis to Canadians. I would 
gladly join in a memorial, or, if necessary, a deputation to the 
Chancellor of the Exchequer, to obtain we reversal of this penny-wise 
policy.—Yours sincerely, 

: Bernarp’ Hopson. 
Tapron EKims, SHEFFIELD. 

January 6, 1910. 


VEE S Cane d= ASIN EE @igis2 


——— 


GrotocicaL Sociery, 1910, Mepats anp Awarps.—The Council of 
the Geological Society have this year made the following awards: 
The Wollaston Medal to Professor W. B. Scott, of Princetown 
University; the Murchison Medal to Professor A. P. Coleman, of 
Toronto University; the Lyell Medal to Dr. Arthur Vaughan; the 
Wollaston Fund to Mr. E. B. Bailey; the Murchison Fund to 
Mr. J. W. Stather; and the Lyell Fund jointly to Mr. F. R. Cowper 
Reed and Dr. Robert Broom. 


Tar Grontocican Survey or Eeypr.—Dr. William Fraser Hume, 
Assoc. R.C.S. and Assoc.R.S.M., F.G.S., who has served for more than 
ten years as a Geologist on the Survey of Egypt, has now been 
appointed Director of the Geological Survey in the Public Works 
Department, Giza, Egypt. He has contributed many valuable papers 

\\on Egypt to the Gronoercan Magazine. 


Errata.—‘‘ Old Granites of the Transvaal and South and Central 
Adrica,2 ‘by C2 B: Horwood & A. WH Set iis authors request to be 
allowed to make the following art L (October, 
1909), p. 455, 1. 1, for ‘‘ Just over Dhaiee years ago”’ read ‘‘ Just over 
four years ago’ ‘On p . 458, 1. 11, for “chrom-iron” read ‘ chrome- 
iron”, In Part III (Detembde 1909), p. 543, 6th line down, after 
“the strike” add comma. On p. 546, 1. 33, for ‘further east ”? 
read ‘‘north-west from there”. On p. 546, l. 34, delete comma after 
“‘Gordonia’”’ and insert a comma after “ generally i 


' 


Ege Tetade V_ Val, VIE—_No, IIL 


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} GROLOGICA 


THE 


L MAGAZINE 


Monthly Journal of Geologp. 


WItH WHICH IS INCORPORATED 


PE ~GCHOLOGES er 


EDITED BY 
HENRY WOODWARD, LL.D., 


ERS .5, hsG.Suaneece 


ASSISTED BY 


Proressor J. W. GREGORY. D.Sc., F.R.S., F.G.S. 
Dr. GEORGE J. HINDE, F.R.S., F.G.S, 


Sm THOMAS H. HOLLAND, K. 


C.I.E., A.R.C.S., D.Sc., F.R.S., F.G.S. 
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Dr. ARTHUR SMITH WOODWARD. F.R.S., F.L.S., Sec.GEOoL.Soc., AND 
HORACE B. WOODWARD, F.R.S. 


pee Gres 


MARCH, 1910. 


I. Oniginat ARTICLES. 


Aiolian Deposits on the Coast at Etel, 

- Morbihan. Part II. By Rev. R. A. 

Burien, B.A. (Lond.), F.L.S., 

F.G.S. (Plates [IX and X and a 

PReREUOITO \orvcen i c.5 ete ne a 

Two Deep Well-Sinkings at Leck- 
hampton Hill, Cheltenham. By 
L. Ricuarpson, F.R.S.E., F.G.S. 
(With a Text-map.) ... ... ... 

On a pre-Tertiary Dyke on the Usway 
Burn. By Miss M. K. Hesnop, 
MeSeeuibiate XD) 2.2 ee 2 2 

On a Mounted Skeleton of a small 
Phiosaur (Peloneustes). By C. W. 
Anprews, D.8c., F.R.S., British 
Museum (Nat. Hist.). (Plate XII.) 

Glacier Granule-markings. By R. M. 
Dertry, M.Inst.C.E., F.G.S. 
(Plate XIII.) RRR eae 

Some Fossil Annelid Burrows. By 
Dr. F. A. Barner, M.A., F.R.S., 
British Museum (Nat. Hist.) 

The Horizon of the Lower Car- 
boniferous Beds with Archeo- 
sigillaria Vanuxemi at Meathop 
Fell. By Prof. E. J. Garwoon, 
M.A., Sec. Geol.Soc. ... 1... 

II. Notices or Memotrs. 

Problems of the 8.W. Highlands of 
Scotland. Presidential Address by 
Professor J. W. Gregory, D.Sc., 
peers Ga eset! ak, a 

III. Reviews. 

Radioactivity and Geology. By Pro- 
fessor J. Joly, M.A., F.R.S.... 

Geologists’ Association Jubilee: 
Geology in the Field ... ... ... 


GO ANG Aa IN ee SS 


REVIEWS (continued). 
Sir Ray Lankester’s Zoology; Pre- 
fessor E. 8. Goodrich’s Fishes 
Paleontographical Society’s vol. lxiii, 
for L9G... < . 


Brief Notices : Soils of South ‘Africa 


—Soils of Hungary — Wakatipu, 


New Zealand—Earth Temperature 
—Tertiary Beds of N.W. Germany 
—Waterberg Tin-field—Mines of 


Finland — Miocene of. Oregon — 
Gotlandian of Fyledal — New 


Zealand Geological Survey—Fossil 


Horse in Africa—Fossil Vertebrates 
of the Karroo—Iron Ores of Egypt 
—Cretaceous of Pondoland—Phos- 
phate Deposits, South Carolina, 
etc. — Geological Time — Royal 
Scottish Museum... ... ... ... 


IY. Rerorts anp PRocEEDINGS. 


Geological Society of London— 
January 12, 1910 ... : 
January 26... ... 
February9 ... .., 

Mineralogical Society— 
January 25 


V. CoRRESPONDENCE. 
J. B. Scrivenor ... 
BPW Bowers -c2; 3, 
Herbert L. Hawkins 

VI. Oxrrvary. 
Rey. G. F. Whidborne, M.A. 


Page 


. 125 


128 


129 


once |ats: 
me loo 
. 137 


. 137 
. 139 


Bae eh 
_ 141 


S141 
VIL. Miscet1 EauesssOnien ist 


Mr. James Reeve, F.G/Sep’and the 
Norwich Castle Musdum 
In Memory of Dr. 
Lesmahagow, Lanark: 


ire 


3 


Ke it 
RE/ le 


_ > The Volume for 1909 of the GEOLOGICAL MAGAZINE is ready, 
price 20s. net. Cloth Cases for Binding may be had, price 1s. 6d. net, 


Sin AB: 2% 19h0 
ioe 


A COMPLETE REPRODUCTION OF THE SKELETON OF 
DINORNIS MAXIMUS 


(the gigantic ‘ Moa’ of New Zealand) as supplied to the Natural History Museum, 
Brussels, by 
ROBERT. F. DAMON, Weymouth, England. 


Height 300 cm. 


GroL. Mac. 1910. Puatr IX. 


G. Merciére phcto., Auray, Briltany. 
Ite, i. ce de Garde, Riviére d’ Etel. 
See Olitinot ‘oranulite’ , left bank, Rivitre d’ Etel. 
3. Ruins of “Cha: nel of Ste. Brigitte, near La Magoire. 
» i 


THE 


GEOLOGICAL MAGAZINE. 


NEW SERIES” "DECADE Ws MV OIE. =Wilz 


No. III.— MARCH, 1910. 


(Gus We MMINAIls) yaad Ce Op Ea snfSs 


sae 


I.— Moran Devosrrs on tHE Coast av Ever, Morsraan. Parr II. 
By the Rey. R. AsHineron Butuen, B.A.Lond., F.L.S., F.G.S.;. ete. 
(PLATES IX AND X.) 
§ 1. Description of microscopic sections of pebbles forming the Raised Beach 
at Ktel. 
§ 2. Description of the photographs illustrating facts contained in Part I of this 
paper. NEED 
fW\HIS brief article is necessitated by the impossibility of procuring 
photographs and rock sections in time for incorporation in my 
former paper in the January number of the GerotoercaL Magazine, 
pp. 6-15. ‘ era 
§ 1. The rocks (i) of the Raised Beach at Htel and (ii) of the 
local granulite (in the French sense of the word) have been submitted 
to Mr. Russell F. Gwinnell, B.Sc., of the Royal College of Science, 
South Kensington, and after having had speciaily thin sections of them 
prepared, he reports as follows :— 


Perrograrnic Descrietion or Rocks From Ler, Brerrany, 
COLLECTED BY THE Rey. R. AsHineton BULLEN. . 
(Puare X, Fires. 1-5.) 

These rocks are all quartzites, varying slightly as to accessory 
constituents, and differing from one another more as to the degree 
in which the superinduced or metamorphic structures are exhibited. 
Textural differences also slightly accentuate the variation in appearance. 
One is reminded of the schistose grits or quartz-schists of the Dalradian 
Series of the South-West Highlands of Scotland, but still more forcibly 
of the Cambrian quartzites of the North-West Highland complex. 

Pl. X, Fig. 1, is a very fine-grained rock, with a foliated structure 
which, though quite well marked under polarized lght, is not apparent 
in ordinary light. It consists mainly of minute elongated granules of 
quartz, forming a fine mosaic of interlocking individuals. ‘Undulatory 
extinction indicates mechanical strain. The rock is. intersected by 
numerous veins running in many different directions, and consisting of 
comparatively coarse crystals of quartz, full of minute inclusions and 
secondary in origin. Many minute rounded grains of an opaque black 
material are distributed throughout the rock, and, by their local 
abundance, render it opaque in patches. This material suggests 
carbonaceous matter, but it is impossible to definitely identify 1t under 
the microscope. Occasional small brownish patches of indefinite 
characters suggest a coloured ‘mica or micaceous: hematite. - 

DECADE V.—VOL. VII.—NO. III. a 


98 Rev. R. Ashington Bullen—MHolian Deposits at Etel. 


Pl. X, Fig. 2, is much coarser in texture, the quartz-grains, which 
are extremely irregular in shape, varying very considerably in 
dimensions. The interlocking of the grains is striking, but foliation 
is not evident. Strain polarization effects are well shown, especially 
in the larger individuals. Small streaks and patches of brown 
material occur, as in Fig. 1, and a shght film of it envelops each 
quartz-grain. Minute inclusions, probably of liquid or gaseous matter, 
are abundant in the quartz, and in places occur in long series, 
continuous through adjacent crystals. 

In Pl. X, Fig. 3, the foliation is again seen to be distinct, and the 
quartz-grains are fairly uniform in size: a sort of groundwork of smaller 
grains has, scattered through it, elongated crystals of much greater 
dimensions, but agreeing approximately in size with one another. 
Many of the crystals, both of the smaller and the larger size, are 
fairly regular in contour, being three or four times as long as they 
are wide. Undulatory extinction is common, inclusions are quite rare, 
while the brown-red indefinite staining material is very abundant, 
and has the characters of hematite in places. 

Pl. X, Fig. 4, is coarser in texture than any of the others. All the 
grains are large and most of them elongated, so that the foliation is 
well seen. Inclusions are not abundant, but in places occur in 
series, especially along lines of apparently incipient fracture. The 
brown-red colouring matter is fairly abundant, and a very lttle mica 
is suggested here and there. Undulatory extinction is again noticeable. 

Pl. X, Fig.5. In structure this rock is holocrystalline, hypidiomorphic, 
without porphyritic constituents; its texture is of medium coarseness. 
The specimen is somewhat decomposed, as is shown by the partial 
kaolinization of felspars, while there is a decided tendency for the 
individual crystals to separate from one another to produce an angular 
sand. In mass the rock is very pale in colour, and white mica, 
felspar, and quartz are easily recognizable; the few dark streaky 
patches seen by the naked eye are found by microscopic examination 
to be biotite. Under the microscope j/elspars are seen to be most 
abundant, the other essential constituents being quartz, muscovite, and 
brotite. The two micas are, in several instances, in parallel growth, 
while the contours of the various crystals show that the micas have 
usually preceded the felspars, and the quartz has succeeded them in 
order of crystallization. The felspars are invariably kaolinized, but 
not to a great extent. In some cases an outer zone of nearly fresh 
felspar surrounds a kaolinized kernel. The simple twinning of ortho- 
clase is seen in numerous crystals, while others are striated. Some 
of these plagioclases show simple twinning together with twinning on 
the albite law, while a very few exhibit the cross-hatching due to 
albite with pericline twinning: these latter may be considered as 
microcline. A number of observations of extinctions in plagioclases 
exhibiting albite twinning gave low readings (5°-12°); thus these 
are oligoclase-andesine. The quartz is clear, with a few minute 
inclusions, and is mostly quite allotriomorphic. The micas are 
abundant, well-shaped, and usually associated in parallel growth. 
The muscovite is quite clear and colourless, while the biotite is of 
a greenish-brown colour with moderately strong pleochroism: its 


Rev. R. Ashington Bullen—MHolian Deposits at Htel. 99 


birefringence shows that the green tint is not due to chloritization : 
inclusions with slight pleochroic halos are found. Accessory and 
secondary constituents (other than kaolin) are uncommon, a little 
granular epidote being alone noteworthy: this is associated with, and 
presumably derived from, decomposed felspars. This rock is a ‘ granite- 
proper’ or ‘two-mica granite’, the ‘muscovite-granite’ of some 
authors, a ‘ granulite’ in the French sense. 


§ 2. The granulite, or muscovite-biotite granite, outcrop can be 
seen in Fig. 1 (Plate IX). The point thus formed is the Cap de Garde 
at the mouth of the Riviére d’Ktel, looking across westward from the 
left bank, at about half-flood tide. I find that the tower (La Tourelle) 
does not stand actually on the rock called Le Chaudronnier ; the latter 
is seen surrounded by water a little behind and westward, and is 
indicated by the white arrow pointing from above it. Consequently 
my former remarks must be modified to this extent, other statements 
of fact, however, remaining unaltered. 

It was in the ‘baylet’ just westward of the granulite that. the 
masses of rolled peat occurred.'. As the prevailing winds are from 
the south-westward, and as strong currents seem to set from westward, 
the source of the submerged peat beds may possibly be to the west- 
ward too. The prevailing current is said to originate in the region 
of westerly winds in the Atlantic, and to flow along the north coast of 
Spain and up the west coast of France to the north-westward, but it 
is much influenced by the prevailing wind and the tidal currents. 

The only submerged peat beds that have been described in Brittany 
lie on the north coast at Plougasnel-Primel, near Morlaix (Finistére). 
The deposit measures roughly 7 ft. 6 in. in thickness, and contains four 
well-defined vegetable layers, the upper containing stools of trees 
(beech, holly, and hazel). There are two well-marked peat beds, the 
upper being ‘40 metre and the lower ‘55 metre in thickness (see 
L. Cayeux, Bibliography, al jfin.). M. Jos. Bourlot also mentions 
a submerge forest (elm) at Pointe du Raz, and suggests others round 
the Bay of Douarnénez (see J. Bourlot, Bibliography, a/ fin.). 

The lines of white quartz pebbles on the left bank are most probably 
derived from old Raised Beaches of Pleistocene age (now obliterated, 
except fragmentarily), just as the pebbles of the Chesil Beach, in 
Dorset, have been derived from beaches of the same age in England.? 

Fig. 2 (Plate [X) shows the cliff (falaise) on the left bank, marked 
Y, --- yy, In the plan. The place from which the ‘granulite’ 
was procured for the microscope is marked with a white x. The 
capping of the cliffs is of blown-sand, with grains of quartz and 
brown and white mica, and contains much finely broken debris of 
Bittium reticulatum, as well as many entire shells of the same 
abundant species. The sand here is of a brown colour, most probably 
due to this fact. This is the finest outcrop of ‘granulite’ between 
Ktel and the sea. Bolder cliffs occur, however, at Pont Lorois, about 

' Grou. Mae., No. 547, January, 1910, p. 8. 


2 Prestwich, Geology, vol. i, p. 99. Minutes of Proceedings of the Institute of 


Civil Engineers, vol. xi, pt. ii, p.4. For summary see Damon, Geology of Weymouth, 
p. 174. 


100 Rev. R. Ashington Bullen—Molian Deposits at Etel. 


3 miles northward. The height of the cliffs at Ktel is about 30 feet. 
The corresponding outcrop opposite, across the river, is almost planed 
down to the level of the shore-sand. 

Fig. 3 (Plate IX) gives the scanty ruins of the chapel of 
Ste. Brigitte looking northward across the river to Etel itself. The 
‘stones, as can be seen, are unmortared, and the whole building is of 
a primitive type of construction. Many shells of Cardium edule occur 
on the east side. With this we may compare the kitchen midden 
surrounding Constantine Church, Cornwall, and that near St. Piran’s 
Church, Perranzabuloe, also in Cornwall, some scanty remains of 
which are still in evidence.!. The narrowness of the door, with its 
stone lintel, and the absence of the arch are noteworthy. ‘The date of 
the building probably approximates more nearly to that of St. Piran’s 
first church, which was completely overwhelmed by blown-sand in 
the seventh century 4.p.,' than to any later date. 

The views (Plate LV, Guor. Mae. for January, 1910) were adapted 
by Miss Gertrude M. Woodward from French views, to the unknown 
authors of which, and to her, my thanks are due. I am also greatly 
indebted to M. Charles Garnier, of Etel, for invaluable help in kindly 
arranging and superintending the taking of photographs of all the 
principal points requiring illustration, a pleasant proof of the reality 
of the ‘ Entente Cordiale’. 
BIBLIOGRAPHY. 


Guitpert, L. Submerged Forests of Brittany (1907). (N.B.—Not in Libraries of 
the Geological Society, or at the British Museum, Natural History.) 

Cayrux, L. “Les tourbes des plages bretonnes, au nord de Morlaix (Finistére). 
Note présentée par M. Michel Lévy.’ Comptes Rendus des Sciences, Paris, 
1905, pp. 468-70. 

“Tes tourbes immergées de la cdte brétonne dans la région de 
Plougasnel-Primel (Finistére). Note préliminaire.”” Bull. Soc. Géol. “France, 
Paris, 1906, tome vi, pp. 142-7 (with one figure). 

M. Cayeux gives the following section :— 


. Sable aw m.). 

Sable tourbeux et tourbe avec souches (+55 m.). 
Sable (*25 m.). 

. Tourbe bane supérieur 4 Roseaux (-40 m.). 
Sable (*15m.). 

. Tourbe (alluvion végétale) (+55 m.). 

Tourbe, bane inférieur 4 Roseaux (*55 m.). 
Sable (:10m.). 


1 Proc. Malac. Soe., vol. viii, p. 247. 


AADNRONrE 


Gxron. Mac. 1910. Prats X. 


Fie. 1. X20 IRE, WD. X20 


Fie. 4. 


H. A.B. Photomicro. Bemrose, Collo. 


Sections of Rocks from Etel, Brittany. 


L. Richardson—Well-Sinkings, Leckhampton Hill. 101 


Notes. 

2. Submerged forest (with tree-stumps): the soil is sandy and the vegetable 
matter is almost transformed into peat. 
. Gray quartz sands with traces of mica. Pebbles (rare) at base. 
. Peat (Arwido phragmites, L..), insect remains, elytra of Coleoptera. 
. Corresponds in material with 3. 
. Small branches of Poplar, Beech, Holly, and Hazel. 
. Peat. Insect-remaims less common than in 4. 


“ID NO CO 


Bovrtort, Jos. Changement de niveauc des sols dans La Brétagne et la presqw ile 
Scandinave. Aire de denivellation dans le nord de 1’ Europe et de lV Asie, 1865. 
Colmar. Bull. Soc. Hist. Nat., 1867, 6 and 7, pp. 3-16 


EXPLANATION OF PLATES. 


Puate IX. 
Fre. 1. Cap de Garde. 
», 2. Cliff of Granulite, left bank R. dEtel. 
», 3. Ruins of Ste. Brigitte, looking northward to Etel. 


Puate X. 


Sections of rocks (Figs. 1 to 4) from the Raised Beach at Etel, Brittany ; prepared 
and described by Mr. R. F. Gwinnell, B.Sc. The photomicrographs were prepared 
by Dr. H. H. Arnold-Bemrose, M.A., F.G.S., under crossed nicols. 

Fig. 1. Section of a very fine-grained rock with a foliated structure. x 20 diam. 

,, 2. Section of a specimen much coarser in texture, the quartz-grains very 
irregular in shape and size. x 20 diam. 

oe] Chis section shows distinct foliation and the groundwork of smaller grains 
with two elongated crystals of greater dimensions. x 20 diam. 

», 4. In this the rock- structure is coarser than in any of the ee all the erains 
large and most of them elongated, foliation is well seen. x 20 diam. 

ap Do As holocrystalline rock, hypidiomorphic without porphyritic constituents, 
texture of medium coarseness. (French ‘granulite’.) x 20 diam. 


I1.—On Two Derr Wett-Sryxines at Lecknampron Hint, CoeLtTenHAM. 
By lL. Ricuarpson, F.R.S.E., F.G.8. 


fF\HOSE who are acquainted with the detailed zoning of the Upper 

Lias and Inferior Oolite of the Cotteswold Hills have long 
desired to know the precise date of the Upper-Lias deposit at Leck- 
hampton Hill, Cheltenham, upon which the Inferior Oolite rests. 
At last the desired-for information is to hand. The Inferior Oolite 
at Leckhampton Hill rests directly upon the Variabilis-Beds of the 
Upper Lias. 

It has, of course, long been known that there is no Cephalopod- 
Bed, like that so well known in the neighbourhood of Dursley, at 
Leckhampton Hill. All the evidence available tends to show that 
the Sevssum-Beds rest directly upon the Variabilis-Beds. That would 
mean that the Opaliniforme-, Aalensis-, Mooret-, Dumortieria-, Dis- 
pansum-, Struckmanni-, Pedicum-, and Striatulum-Beds were absent 
from Leckhampton Hill, and that there is a considerable non-sequence 
there between the Inferior Oolite and Upper Lias. As regards the 
Cotteswold Sands alone, ‘‘ there is a loss of about 140 feet from Coaley 
Bs to Leckhampton Hill” (S. S. Buckman, in litt., November 11, 
1909 

Unfortunately, the actual junction of the Oolite and Lias could 
not be investigated in the deep well from which the fossils indicative 


102s L. Richardson—Weill-Sinkings, Leckhampton Hill. 


of a deposit of variabilis hemera were obtained. The well had 
already long been made when the Birmingham Corporation acquired 
the Salterley-Grange Estate for the purpose of establishing a Sana- 
torium there for consumptives, and it had only to be cleaned out 
and deepened. 

At all events, as far as can-be gathered from evidence collected in — 
the immediate neighbourhood, and what could be seen at the well- 
sinking itself, in the form of rock dug out, etc., the Inferior Oolite 
rests directly upon the greyish-blue sandy micaceous clays of 
variabilis date. 

The well under consideration is situated between the two Hartley 
Cottages, which lie between Hartley Farm and the Sanatorium (see 
Map, Text-fig. 1). The site is now marked by the building that 
houses the pumping-engine. 

We t at Harriry Corraces.—The well was commenced either 

It is doubtful in 


a 


“vas, 


ieee 


Fig. 1. Map (1 inch = a mile) to show the positions of the wells and trenches. 
(1) Hartley-Bottom Well; (2) Hartley-Cottages Well. 


with this one, there appeared to be indications of a small fault, 
which brought the Upper Zrigonia-Grit on the Hartley-Cottages well 
side into juxtaposition with the Clypeus-Grit. 

From surface-level down to the top of the Upper Lias was 
212ft.4in. This thickness certainly includes a considerable portion 
of the Upper Zrigonia-Grit. As the measurement made by me (vide 
Proc. Cotteswold Nat. F.C., vol. xv., pt. 8, 1906, p. 184) in the 


L. Richardson— Well-Sinkings, Leckhampton Hill. 108 


large quarries on the escarpment gave about 200 feet as the thick- 
ness of the Inferior-Oolite deposit between the Upper Trigonia-Grit 
and the Upper Lias, the one total confirms the other. 

The details obtained at the Hartley-Cottages well may thus be 


summarized :— 


WELL-Sinkine aT Harriey Corracres, Lecknampron Huu. 


Thickness in fe. in. 

Inventor f Clypeus- and Upper Trigonia-Grits. i 
‘OoxrTe. | Beds between the Upper Trigonia-Grit and Upper Lias. . .. 200 0 
Hard, greyish-blue sandy micaceous clay. Hal 3 9 

2, Yellow ferruginous, micaceous, indurated, ‘sandy. clay ; 


Nautilus, Belemnites Ae Sona small me © 
| 3. Greyish-blue clay similar tol . . . 6 4 
| 4. More arenaceous but otherwise similar clay it @ 
=, 5. Greyish-blue sandy rock: Belemnites (near to B. Gubuluns is, 
i Y. & B.),! Haugia grandis, S. 8. Buckman,?! Haugia 
ale sp. indet.,! Duactylioceras ct. Holandyei (d’Orbigny),! 
ss D. ck. mucronatum (WV Orb.),! Thysanoceras sp. (fragment: 
4 ? T. sublineatum, Oppel, sp.),! aoa demissis, 
a (Phillips), auctt., 1 Te ya sp. : Sie! 16 ile 1S 
ey Bottom of well (226 ft. I 272. Water ran away. 
5 Bone 
6. Sandy clay. . Sa ammeter ures are itll BS) 
\ 7. ‘“Very fine blue sand”? : penetrated . ee dt 3 oe 2am 3 


[In this well the water-level stood at 210 ft. 1 in., and aid n not rise on the well 
being deepened, but ran away at 226 ft. 1 in. | 


I am indebted to Mr. 8. S. Buckman for naming the ammonites. 

In connexion with the same water-supply scheme that required the 
deepening of this Hartley-Cottages Well, a new well was sunk near 

“the cottages at the northern entrance to the wood in Hartley Bottom ; 

and two trenches were dug—the one connecting the Hartley-Bottom 
well with that at Hartley Cottages; and the other, the well at the 
latter place with the Sanatorium. 

The sites of the wells and the courses of the trenches will be 
apparent from the small map (Fig. 1). 

_Wett in Harttzy Borrom.—This well was commenced in the 
Oolite Marl and left off in the Pea-Grit. Some of the pieces of Pea- 
Grit that were dug out were as blue as Forest Marble. 

PrpE- TRENCH coNNECTING THE Harritey- Borrom anp Harttey - 
Corragres Wrtis.—As already remarked, there appears to be a very 
slight fault at some 60 yards along the trench away from Hartley 
Cottages in the direction of the Hartley- Bottom well. Thence 
onwards, however, to within 150 yards of the latter well the trench 
was in the Clypeus-Grit, which was full of the ordinary fossils. 

Above the Clypeus-Grit exposed in the trench—especially about the 
middle portion—was a foot or more of tough, purplish clay—residual 
soil from the weathering of the Fullers’ Earth. In the stretch from 
150 yards of the well to the well itself, was observed evidence of the 
Upper Zrigonia-Grit (? Gryphite-Grit), Buckmani- Grit, Lower Trigonia- 
Grit, and Upper Freestone. 

_ PIPE-TRENCH BETWEEN THE Harrtry-Corraces WELL AND THE 
Sanatortum.—For the first 300 yards this trench was in the Upper 


1 These specimens are now in the Cheltenham Town Museum. 


104 Miss MW. K. Heslop—Pre-Tertiary Dyke, Usway Burn. 


Trigonia-Grit, but then, as the surface of the ground declined in the 
field just to the north of the Sanatorium-bungalows, the oyster-layer 
on top of the Upper Zregonia-Grit, the thin representative of the 
Notgrove Freestone (with bored and oyster-covered top-layer), and 
Gryphite-Grit were successively proved. Then came a small fault, 
the Fullers’ Earth being let down against the ‘Grit’. The Fullers’ 
Earth, is, however, only a small mass, for the Clypeus-Grit rises up 
from beneath it but a few yards farther on, and is excellently exposed 
in the vertically-cut bank at the back of the bungalows. 

I am indebted to Mr. J. W. Gray, F.G.S., of Cheltenham, for much 
of the information upon which this paper is based. He obtained the 
details of the Upper-Lias deposits exposed in the well, and collected 
the fossils that afforded the information as to their date. 


IIJ.—Nores on a pre-Tertrary Dyxr on tur Usway Born. 
By Miss M. K. Hustor, M.Sc. 
(PLATE XL) 
DYKE of pre-Tertiary age is exposed in the lower course of the 
Usway Burn, a tributary of the Coquet. It is intruded among 
the Cheviot igneous rocks, and crosses the burn in a somewhat north- 
easterly direction. In hand-specimens the rock appears black or 
dark brown with a sub-vitreous lustre, and contains porphyritic 
crystals which are quite visible to the unaided eye. It weathers 
a bright red colour and even the fresh portions are streaked with red. 
veins of agate. 

In his paper on the Cheviot Andesites and Porphyrites,’ Dr. Teall 
mentions a. rock allied to pitchstone-porphyrite, which is exposed on 
the Coquet about a quarter of a mile above Windy Haugh. The 
description. he gives of it would serve very well for the Usway Burn 
Dyke, but he deals chiefly with the nature of the prevailing pyroxene, 
and not at all with the minute structure of the rock. 

Under the microscope the porphyritic nature of the Usway Burn 
Dyke is at once evident, large phenocrysts of felspar and pyroxene 
being embedded in a rather dark glass crowded with elementary 
crystals. Between these two extremes is a medium-sized set of 
crystals, which may be referred to as the ground-mass generation. 
There are some rounded masses of a black oxide of iron which bear 
such evident traces of corrosion that they must be classed, with the 
porphyritic elements, among the products of an earlier period of 
crystallization. It is extremely difficult to determine the order in 
which the crystals were formed—particularly as the limits of the 
generations are very ill-defined—but there can be little doubt that the 
apatite needles and small grains of iron oxide, which are both included 
in the porphyritic crystals, are the oldest secretions of the magma. 
The porphyritic pyroxenes are older than the felspars by which they 
are frequently enclosed. So that in this, the first generation, the 


1 «Notes on the Cheviot Andesites and Porphyrites,’”’ by J. J. Harris Teall, 
M.A., F.G.8.: Gor. Mac., April, 1883. 


Miss M. K. Heslop—Pre-Tertiary Dyke, Usway Burn. 105 


minerals crystallized out in the following order: (1) and (2) apatite 
and iron oxide, (3) pyroxene, (4)felspar. The same order is preserved 
in the ground-mass generation, with the addition of a micaceous oxide 
of iron towards the close of the period. It is remarkable, however, 
that felspar laths of the normal ground-mass type are included in the 
porphyritic pyroxenes, and sometimes in the outer zones of the large 
felspars. At present there is no really satisfactory way of accounting 
for this apparent contradiction to the observed order of formation. In 
the last generation the elementary felspars take precedence of the 
pyroxenes, while much of the iron oxide still exists in an unindi- 
vidualized state. There is apparently some overlapping of the 
periods of formation, but the crystals are classed chiefly by their 
state of preservation and their size. 

The following figures give some idea of their relative dimensions. 
The first number in each bracket refers to the length, and the second 
to the breadth of the section. 

Porphyritie felspars (1:14 X *61mm.), (1:96 x -46mm.), (1°32 x 
‘70mm.) are of common occurrence, while (-43 x ‘28 mm.) is very 
small. 

Porphyritie pyroxenes, longitudinal sections: (1°4 X *d53mm.) is 
large ; (1°12 x :18 mm.) and (-96 X °50 mm.) are more usual; (°36 x 
-24mm.) is small. Some cross-sections are (‘76 X ‘71 mm.), (-39 X 
“32 mm.), (52 x 50 mm.). Longitudinal sections of the ground-mass 
felspars vary from (°34 X ‘18mm.), which is unusually large, to 
(035 x -0llmm.); the average size is about (12 X ‘03mm.). The 
largest cross-sections do not exceed (-12 X ‘21 mm.), and are generally 
yery much smaller. Longitudinal sections of ground-mass pyroxenes 
vary from about (-150 x 180mm.) to (051 xX 027 mm.). When 
smaller than this they are commonly included among the elementary 
forms. 

The porphyritic felspars may, for the convenience of description, be 
divided into three groups. 

1. In the first are those with sharp angles, and clear, well-defined 
edges (see upper phenocryst in Figs. 1 and 2, Pl. XI). They are 
characterized by a combination of simple twinning with that of the 
albite type, e.g. one-half of a crystal may be untwinned while the 
other shows the ordinary albite strie. Glass inclusions are common, 
but not conspicuous, and although traces of zoning have been observed, 
they are most indefinite, and entirely confined to the outer limits of 
the crystal. 

2. A second set comprises those felspars which have a deep 
peripheral zone of glass inclusions, bounded by a complete though 
narrow zone of felspar material. ‘These crystals are characterized by 
rounded angles and clear twinning of the albite type. They are 
usually made up of several particles, intergrown under plutonic 
conditions, apparently in some cases, then, as a group, furnished with 
a zone of glass inclusions and an outer felspar envelope, while at other 
times it is clear that these were added before the particles were 
grouped together, for each possesses complete zones of its own. 

Sections of these groups 7x the zone of inclusions are apparently 
riddled with glass (see lower phenocryst in Figs. 1 and 2, Pl. XI), 


106 Miss IW. K. Heslop—Pre-Tertiary Dyke, Usway Burn. 


and consist more of glass than of felspar, but the condition of the 
section does not necessarily indicate that of the whole crystal or 
erystalline group.’ 

3. The third set is characterized by deep zoning, sharp edges, few 
inclusions, and very indefinite twinning. Although distinct, these 
three types are probably due merely to different directions of the 
sections, or at most to slightly different physical conditions during 
erowth. They do not imply three generations of porphyritic 
felspars. 

The ground-mass felspars are broader and shorter than those which 
conmonly occur in the post-Tertiary dykes of Northumberland and 
Durham.? They show a combination of binary and multiple twinning, 
and on the whole are very free from inclusions, although they do 
sometimes contain rounded or oval patches of dark glass, and are 
pierced by apatite needles. They are very markedly zoned. 

The porphyritic pyroxenes are exactly like those which are described 
by Dr. Teall in the paper to which I have already referred. There 
he concludes that the prevailing pyroxene in the Cheviot Andesites 
and Porphyrites is not, as was previously supposed, augite, but 
hypersthene., 

In the pyroxene of the Usway Burn Dyke, sections which are cut 
perpendicular to the prism are octagonal, but the pinacoidal faces are 
largely developed at the expense of those of the prism (see Figs. 5 
and 6, Pl. XI). Cleavages parallel to both are usual, but that of 
the prism is the more distinct. These sections are decidedly pleochroic, 
the colour changing from yellow to reddish brown. They show 
straight extinction, and, in the vast majority of cases, a bisectrix in 
convergent light. Longitudinal sections, in which pleochroism changes 
the colour, from green for rays vibrating parallel to the length of the 
section, to yellow, for those vibrating at right angles to it, also show 
the point of emergence of a bisectrix, usually giving a much clearer 
figure than the cross-sections. They also show straight extinction. 
The cases in which an optic eye is obtained are various, but they 
generally have good traces of the brachypinacoids, and sometimes 
of the dome faces. 

A combination of these sections gives a crystalline form like that 
described by Dr. Teall as a ‘columnar doubly-terminated crystal, 
which is made up mainly of the pinacoidal and only to a slight 
extent of the prismatic faces’”’, while the consideration of the pleo- 
chroism and the interference figures shows that we are dealing with 
a crystal in which the axes of elasticity coincide with the erystallo- 
graphic axes, so we are justified in assuming that it is orthorhombic. 
That it is hypersthene and not enstatite or bronzite is shown by 
the strong pleochroism, and the constant occurrence of the clearest 
interference figure (bisectrix) in the least pleochroic sections (green 
and yellow), and the occurrence of a less definite figure in the normal 


1 Teall, Gnot. Mac., 1887, ‘‘ Notes on Cheviot Andesites and Porphyrites,”’ 
p. 160: “Tn this case the bulk of the foreign matter must be greater than that of 
the felspar substance, and yet the felspar has ‘impressed its character on the compound 
mass.’ 

2 Teall, Q.J.G.S., 1884, p. 229. 


Miss M. K. Heslop—Pre-Tertiary Dyke, Usway Burn. 107 


transverse sections—in other words, the acute bisectrix coincides 
with the brachydiagonal and the crystals are negative. These are 
the characteristics of hypersthene. 

Dr. Teall claims that a monoclinic pyroxene is also present in 
the Cheviot igneous rocks, and mentions twinning (parallel with 
the pinacoids) which, he suggests, only takes place in the mono- 
clinic mineral. Twinning parallel both to the prism and pinacoids 
may be seen in the Usway Burn pyroxene, but it is found sometimes 
in crystals which are undoubtedly orthorhombic. There are, however, 
certain sections noticeable in ordinary light for their irregular outlines, 
deep cleavage, and dark colour—but little changed by pleochroism— 
and between crossed nicols for their brilliant interference colours 
and frequent twinning. There can be little doubt that they are 
monoclinic crystals of augite. Sections perpendicular to the prism 
give, in convergent light, a dark arm surrounded by coloured bands. 
Sections parallel to the prism give various and somewhat doubtful 
figures, never a good bisectrix. 

In a much decomposed specimen of the rock, all the large well- 
formed pyroxenes are altered to colourless masses streaked with 
green fibres of chlorite, and including little dark rods. Patches of 
the original mineral may sometimes be found towards the centres 
of these crystals, and in one or two cases the fresh portion was 
distinctly twinned. It would be difficult to say, in these circum- 
stances, whether the fresh portion is orthorhombic or monoclinic, 
but that the whole crystal was originally orthorhombic is beyond 
question. In this altered specimen the only wholly fresh crystals 
are those described above as augite, and although some orthorhombic 
sections are only partially decomposed, they belong to the ground-mass 
generation. It would seem, then, that both orthorhombic and mono- 
clinic pyroxenes are present, but that the former is either older or 
more readily decomposed than the latter; also that twinning is common 
to both, and is probably, in the orthorhombic mineral, a precursor of 
decomposition, perhaps of optical re-orientation. 

It is difficult to draw a definite line between the porphyritic and 
ground-mass pyroxenes. The latter, unlike the felspars of their own 
generation, occur in exactly the same way as their porphyritic 
equivalents. They are always surrounded by a little halo of pale 
yellow material with which the incomplete crystals (of common 
occurrence) are intergrown in a way that recalls the micro-pegmatitic 
intergrowth of quartz and felspar (see photographs 5 and 6). There 
is no clue, however, to the identity of the intergrown substance in 
the case we are considering, for although it is not absolutely isotropic, 
its interference effects are too feeble to be of any use. These in- 
complete crystals may be correlated with the incomplete prisms of 
the third generation, a description and suggested explanation of 
which is given later. 

In a decomposed specimen of rock, the pale zones surrounding 
altered pyroxenes, both large and small, become very conspicuous, 
and contain tiny prisms of the fresh mineral, lying with their 
axes parallel to those of the large crystals to which they are 
attached. 


108 Miss M. K. Heslop—Pre-Tertiary Dyke, Usway Burn. 


Tar Guassy Bast. 


With low powers it looks as though the porphyritic and ground-mass 
crystals were embedded in an almost homogeneous dark-brown’ 
background ; but when the latter is examined with higher powers, 
it appears that the ultimate base is colourless and contains numbers 
of brown patches which give the characteristic colour. These patches 
have borders of a yet darker hue (see Fig. 4, Pl. XI), and from their 
corners send out processes into the clear base. The highest powers, 
cannot resolve the brown areas into any constituent part, but if may 
readily be seen that the dark edges are due to numbers of globulites 
which also form the processes, being carried out apparently on a central 
thread of material from the patch. 

The dark areas show a marked tendency towards angularity of 
shape, many are rectangular, while others have more hexagonal 
outlines. They are considerably deformed by the protrusion of the 
globulitic processes, which, besides obliterating the corners, curve 
the sides. Some are quite shapeless. The colour of the glass is 
greatly intensified by numbers of small reddish-brown hexagons of 
a micaceous oxide of iron, probably hematite (see Fig. 4 in Plate). 
These little plates are never very thick, for sections perpendicular 
to them always give quite narrow dark needles. Irregular grains 
of a black oxide of iron are fairly common.’ They have never been 
known to show any definite crystalline form, and are probably in 
a very elementary stage of development. Crystals of the iron 
oxides, like those of the pyroxene (see Fig. 5, Pl. XI), are sur- 
rounded by light-coloured areas when embedded in a dark patch. 
Apatite is repeated in this generation in small but very perfect 
needles, which pierce all the other crystals and are certainly older 
than most of them, although the precise relation of their age to 
that of the apatites of earlier periods of crystallization is somewhat 
obscure. The early felspars are of the same type as those of the 
ground-mass. The crystals in this case, however, are only solid at 
the centre, and grow in hollow tubes in both directions, con- 
sequently longitudinal sections show the well-known ‘hour-glass’ 
structure (see Fig. 3, Pl. XI), while cross-sections of any but the 
central part show square colourless. frames of felspar material filled 
with glass. No globulitic stage of felspar growth has yet been seen, 
the very earliest recognizable forms being faint colourless streaks, 
only visible when surrounded by dark glass. 

The simplest elementary pyroxenes are short cigar-shaped prisms 
which occur either in pairs or groups, rarely alone. All possible 
combinations of these have been observed. ‘he pairs are attached 
at their centres, while the ends of both curve away from each other, 
thus imitating the ‘hour-glass’ structure of the felspars. Some 
assume the usual skeleton form, consisting of a central stem with 
little perpendicular arms attached on either side; others adopt the 
curving acanthus-like structure which is so strongly developed in the 
Collywell and Crookdene Dykes of Northumberland.' 


1 « Notes on the Crookdene and Related Dykes,’ by M. K. Heslop, M.Sc., and 
Dr. J. A. Smythe, read before the Geological Society, November 17, 1909. 


Miss WM. K. Heslop—Pre-Tertiary Dyke, Usway Burn. 109 


The largest elementary pyroxenes are prismatic in shape, and they 
appear to grow by the addition of material at the corners, and it is 
remurkable that quite detached particles are often arranged i” line 
with each other and with the edge of a small pyroxene, for consider- 
able distances. In one case a ‘ process’, about ‘0375 mm. in length, 
protrudes from the end of a small prism of pyroxene, and is made up 
of several apparently quite detached particles. ‘The intervals between 
them are too minute to be correctly estimated—it is quite evident, 
however, that each piece is separate. 

This kind of growth seems to prevail among the elementary pyroxenes, 
because, not only are there innumerable examples of it, but in the 
more advanced crystals cross-sections with good octagonal forms and 
sharp angles often show a gap filled with glass running across the 
centre of the section almost at right angles to the pinacoids (see 
Figs. 5 and 6, Pl. XI). If we refer again to the simplest elementary 
pyroxenes, those consisting of two cigar-shaped needles joined at the 
centre, but with tapering ends diverging apart, we see that there is 
a tendency for pyroxene to grow in incomplete, perhaps hollow, prisms 
from a solid centre, as in the case of the ‘ hour-glass’ felspars. This, 
no doubt gives rise to the centrally mcomplete sections which have 
just been described, and to the intergrowth of pyroxene with the pale 
yellow material—again in incomplete crystals—which occurs in the 
ground-mass generation (see description of ground-mass pyroxenes). 
The gaps are always filled by this pale yellow, feebly doubly- 
refracting substance, which seems indeed to have been brought almost 
to a erystallizable state by the subtraction of pyroxene material to 
build the crystals of that mineral. 

In one slide the glass is in a much more developed stage. The base 
is still colourless, but there is a marked increase in the number of 
elementary crystals, especially the iron oxides and the little pyroxene 
needles. The brown patches have practically disappeared, but their 
final stages may be recognized in the small clouds of dark granules 
which are usually associated with elementary pyroxenes. 

A practically unbroken transition from the dark granules to definitely 
hexagonal plates of micaceous iron oxide has been made out. With 
a magnification of 1000 diameters, very small granules may be seen 
to possess hexagonal outlines, and although many may belong to the 
black oxide, there can be little doubt that the brown patches of the 
normal glass are here very largely represented by hexagons of micaceous 
oxide of iron. 

In the same way, and with equal certainty, a transition from the 
globulitic processes of the brown patches to the elementary cigar- 
shaped pyroxenes may be traced. These may be certainly identified 
by their interference colours, needles with a thickness of less than 
00236 mm., giving quite recognizable interference tints. It is 
impossible to say definitely whether these early forms are orthorhombic 
or monoclinic, but the number of cases in which the extinction is 
oblique suggests the latter. 

The association of pyroxene and iron oxide in the brown patches is 
similar to the association of the basic elements, augite and iron oxide, 
in the ‘ basic globulite’ of the post-Tertiary Dykes of Northumberland. 


110 Dr. C. W. Andrews—The Skeleton of Peloneustes. 


A careful study of the mode of occurrence of elementary crystals in 
them shows that the growth of a skeleton augite is almost invariably 
accompanied by the elimination of iron oxide at intervals along the 
-stem and arms of the skeleton crystal. Here, the reverse occurs. 
The brown patch (which may be regarded as an enlarged basic 
elobulite) contains the ingredients both of the pyroxene and iron 
oxides, the latter apparently in excess of the former. The pyroxenic 
constituent separates out in globulitic forms, segregates at the edges 
of the patches, and is gradually eliminated as the globulitic processes 
break off and become definite elementary pyroxenes. It is not 
suggested that after this the brown patch merely assumes hexagonal 
outlines—although its somewhat marked angularity seems to indicate 
an inclination to do so. The process is, no doubt, much less simple, 
and must involve a differentiation between the hematite and the black 
oxide of iron; but it is certain that these minerals do assume a more 
or less definite crystalline form after concentrating as much as possible, 
and so eliminating the pyroxenic material. 


EXPLANATION OF PLATE XI. 
Rock-sEctTions, PRE-TrERTIARY Dyxr, Usway Burn. 


‘Fig. 1. This shows the general structure of the rock. There are two types of 
porphyritic felspars : the upper one belongs to the first set, and has few 
inclusions and clear sharp angles and edges. The lower one has rounded 
angles and is riddled with inclusions: it belongs to the second set. 
x 22°6 diameters. 

Shows the same field between crossed nicols. 

This shows the mode of occurrence of the elementary felspars. The 
‘hour-glass’ structure is well seen in the small longitudinal section 
which occurs near the centre of the field. x 260 diameters (approx.). 

., 4. This emphasizes the dark borders of the brown patches, and shows the 
globulitic nature of the processes. In the centre of the field there is 
a small hexagon of the micaceous iron oxide, in which different thick- 
nesses (due to incomplete cleavage-plates) have produced different 
intensities of colour. x 260 diameters (approx.). 

,, 5. An incomplete pyroxene is seen here. Although it occurs in a dark patch, 
it is surrounded by a zone of light-coloured material, which also fills the 
gap extending across the centre of the crystal. There are several small 
detached pieces of pyroxene near the lower left-hand corner of the 
crystal. x 208°3 diameters (approx.). 

,, 6. Shows the same with nicols crossed. This brings out clearly the isotropic 
nature of the colourless material which forms the zone and the central 
inclusion. 


cw bw 


2? 


IV.—Nors on a Movntep Sxererron or a Smart Prrosaur, PLLONEUSTES 
PHILARCHUS, SEELEY, SP. 
By C. W. Anprews, D.Sc., F.R.S., British Museum (Natural History). 
(PLATE XII.) 
Boa skeleton figured on Plate XII is that of a small Plosaur, 
Peloncustes philarchus, Seeley, sp. This specimen was obtained 
‘from. the Oxford Clay in the neighbourhood of Peterborough by 
Mr. A. N. Leeds, F.G.S., to whom the British Museum is indebted for 
-a great series of more or less perfect skeletons of many species of 


1 Published by permission of the Trustees of the British Museum. 


3HOL. Mac. 1910, Prate XI, 


x 208°3 


Rock-sections from pre-Tertiary Dyke, Usway Burn. 


Dr. C. W. Andrews—The Skeleton of Peloneustes. 111 


Oxford Clay Reptiles, including the beautifully preserved and nearly 
complete examples of Cryptocleidus oxoniensis and the remains of 
Cetiosaurus leedsi, now mounted in the Gallery of Fossil Reptiles. 
So far as I am aware, this is the first skeleton of a Pliosaur that has 
been mounted so as to show the true form of the body in those reptiles. 
All the bones belong to a single individual, but the left-hand paddle 
and the distal portion of the other paddles being wanting, they have 
been represented by plaster models made from the paddles of another 
individual, which are exhibited on the floor of the case. The left 
ischium has been modelled from that of the opposite side. 

Peloneustes philarchus was first noticed by the late Professor H. G. 
Seeley’ under the name Plesiosaurus philarchus. Subsequently 
Mr. Lydekker? gave a more complete account of the species and 
referred it to a new genus, Peloneustes. The structure of the skull 
was described by the present writer in the Ann. Mag. Nat. Hist., 
1895, ser. vi, vol. xvi, p. 242. é 

Peloneustes, though considerably smaller than the other Pliosaurs, 
exhibits all the characters peculiar to that family, viz. relatively large 
head, short neck with double-headed cervical ribs, absence of a median 
symphysis of the scapule, greatly elongated ischia, and hind paddles 
larger than the fore. Mr. Lydekker, however, considers that in some 
respects it is more primitive than the larger forms, and tends to 
bridge the gap between them and the true Plesiosaurs. 

The skull, which in the present specimen is somewhat crushed and 
distorted, is relatively large and the snout is considerably elongated, 
the length of head being about two and a half times its width at the 
posterior end. There are six tecth in the premaxilla, and twenty- 
eight to thirty in the maxilla; in the lower jaw there are about 
thirty-five teeth on each side, of which fifteen to sixteen are in the 
symphyseal region. The teeth themselves are slender and sharp- 
pointed; they are circular in section, and the enamel-covered crown 
bears numerous fine longitudinal ridges, some of which extend to the 
apex. The neck is short, and is composed of twenty-one or twenty- 
two vertebree, including the atlas and axis; the centra are short and 
slightly biconcave, the neural arches and spines are high. All the 
cervicals behind the united atlas and axis, with the exception of the 
last, bear double-headed ribs, but the facets for the upper and lower 
heads are separated by a slight ridge only; the last cervical seems to 
have had only one head, and the same is the case with the pectorals 
and dorsals. Of these there seem to have been two or three of the 
former and twenty-two or twenty-three of the latter, all bearing 
comparatively slender ribs. The number of sacral-and caudal vertebree 
is not definitely known. 

The shoulder-girdle is typically Pliosaurian, the coracoids are large 
thin sheets of bone; the scapule are triradiate, but the ventral rami 
do not meet one another in the mid-ventral line, nor do they meet the 
coracoid. Some specimens show that a triangular interclavicle was 
interposed between the ventral ends of the scapule. The fore paddle 


1 Index to Aves, etc., in the Cambridge Museum, 1869, p. 139. 
* Quart. Journ. Geol. Soc., 1889, vol, xlv,. p. 48. 


112 R. MW. Deeley—Striations on Glacier Granules. 


is smaller than the hind; the humerus is only slightly expanded at 
its lower end, and the rest of the paddle is long and slender. The 
pelvis consists of small rod-lke, backwardly sloping ilia, great thin 
plate-like pubes, and the greatly elongated ischia characteristic of the 
family. As usual in the group, the ium is not in contact with the 
pubes in the acetabulum. The greatly expanded coracoids, pubes, and 
ischia formed an almost continuous bony floor to the body, and the 
short interval between the posterior edge of the coracoids and the 
anterior edge of the pubes was filled by a plastron of ventral ribs; in 
the mounted. specimen this is represented only by three of the median 
ventral ribs, which are fused with one another on the middle line. 
The hind paddles, though larger, are closely similar in form to the 
_ fore paddles. The total length of the specimen as mounted is 11 ft. 6 in. 
The dimensions in centimetres of some parts of this skeleton are— 


Skull, length . : per 8, 3 : 55°7 centimetres. 
Mandible, “leneth ; ‘ : ; ; 67°0 Bi 

as length of symphysis 21:4 5 
Coracoid, greatest length : f : 47:0 5 
Humerus, ‘length : : : : : ; 33°0 - 
Pubes, leneth 3058 i 
Ischium, length of median expansion 37:0 + 
Femur, leneth 39°0 


39 


V.—Gatacrer GRANULE-MARKINGS. 
By R. M: Drevey, M.Inst.C.E., F.G.S. 
(PLATE XIII.) 


HAVE already described the granular appearance of glacier ice 

as seen in polarized ight! and also the striations on the granules 

as shown by pencil rubbing gs.” Last summer I succeeded in obtaining 

exact reproductions, in plaster of Paris, of the ice surface-structure in 
the upper cave in the Rhone Glacier. These are shown in Figs. 1-8. 

The casts were obtained in the following manner. Plasticene, 
a substance used for modelling, having been cooled to the temperature 
of the ice, was pressed against the wall of the cave. When all the 
conditions were favourable the surface of the plasticene took an exact 
impression of the ice-surface. A cardboard ring, obtained froma pillbox, 
the top and bottom of which had been removed, was then pressed 
upon the surface of the plasticene and filled with liquid plaster of 
Paris. When the plaster had properly set the plasticene and card- 
board were removed. Photographs of these casts, as will be seen 
from the photos reproduced, give very good representations of the 
ice markings (see Plate XIII). 

A careful examination of well-marked granules in which lquid 
cavities had been produced by a burning-glass showed that the ridges 
and furrows in each grain were along planes at right angles to the 
optic axes of the granules. It is clear, therefore, that the direction 
of the markings is determined by the crystalline structure of the ice. 

Fig. 2 is a print of a portion of the surface of a large glacier 
eranule, and Fig. 1 shows portions of several granules. ‘Fig. 3 is 


1 Grox. Mac., 1895p. 152. . 2 Thid., 1907, p. 529. 


At se , acre LV e 1 3 AG o pp ) f | « / sags / | IS 
¥ Ww U q 10G Qo 1 OG. be d A" ) i ds cS) ke) \ YOU SAISNAUO0IA OT Oo \ 
4 2. 2 OF hod 1939 B XxX nN 
OZIS I ho LO r ad o C 
. T h e . D > 


\\M ret 


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Weer 


\ eee a 
“Fa tes tan et Nebel 


TIX SivTg 
‘O1GT “PVN “Tom 


Rk. M. Deeley—Striations on Glacier Granules. 113 


a still further enlargement of a portion of Fig. 2 to show more clearly 
the details of the surface-structure. It will be seen that both the 
ridges and the furrows frequently bifurcate, and that whilst main- 
taining their general direction across the granules they curve about 
considerably. Fig. 1 shows several granules abutting against each 
other. ‘Che most marked feature is that some of the surfaces of the 
granules occupy depressions, whilst others project above the general 
level of the surface. The surface was originally quite level, and 
evaporation and melting have taken place on the surfaces of some of 
the granules more rapidly than upon others. The coarseness of the 
grooving on different granules varies somewhat. In Fig. 1 all the 
granules differ in this respect. Compare the fineness of the grooving 
on the larger granule with the coarse incipient grooving on the 
top one. 

The rubbings I had previously obtained seemed to show that 
even when protected from the sun, as in a cave, each granule 
was separated from its neighbour by a canal of more or less 
width. These actual impressions, however, make it clear that this 
appearance was produced by the pencil passing from raised to depressed 
granule surfaces and vice versa. Sometimes the grooving of the 
surface of the lower crystal is not well marked near its junction with 
other granules. This is probably the result of capillary forces 
causing water to collect along the line of junction. Evaporation 
rather than melting appears to be the main cause of the appearance of 
the surface-structure we are considering. It occurs at all points in 
caves both in the light and in the dark. Ventilation appears to have 
the most marked effect on its appearance; for the surface-markings 
were very well developed in many of the crevasses intersecting the 
ice cave. 

I have never seen the structure on lake ice, pieces of which have 
been exposed in a freezing atmosphere. Shear planes in the granules, 
produced by the differential motion of the glacier might produce the 
ridges and furrows. O. Mugg! says ‘“‘ broken surfaces, especially those 
of bent bars of ice, almost always show a fine striation’’. With regard 
to McConnell’s work on the bending of ice Mugg’ says, ‘‘ As 
McConnell died during these experiments I decided to take them up 
again, and especially to make the experiment to produce in the ice 
the pure translation without curvature and also if possible to ascertain 
the direction of the translation.” ‘‘The result was a complete con- 
firmation of McConnell’s experiments.” Mugg’s investigation was 
a very exhaustive one from the point of view of the chemist and 
erystallographer. 

The microscopical examination of polished surfaces of alloys which 
have been sheared shows that the distortion takes place along definite 
shear planes in the crystals and not equally throughout the mass, as 
in amorphous liquids. Crystalline ice, it would appear, also shears 
along definite planes, and the distortion in the crystalline structure 
along such planes results in differences of surface evaporation, which 
give rise to the surface ridges and furrows. 


1 Jahrb. fiir Min., 1895, p. 217. 2 Tbid., pp. 213, 214. 
DECADE Y.—YOL. VII.—NO. III. 8 


114 Dr. F. A. Bather— Fossil Annelid Burrows. 


From these considerations it appears that the differential motion of 
glaciers is partly the result of viscous shear between adjacent 
granules; partly of viscous shear along planes at right angles to 
the optic axes of the crystalline granules; partly of the plastic 
shearing into separate pieces of the granules and to the viscosity 
imparted to the general mass by the growth of one crystal at the 
expense of another. It is to this latter giving way of the points of 
attachment between granule and granule, owing to molecular move- 
ments at their interfaces, that the general viscosity of the glacier 
depends. The deformation of the granules by stress and the formation 
of extensive shear planes by the breaking up of granules are secondary 
effects. 


EXPLANATION OF PLATE XIII. 
Fig. 1 shows a portion of the ice surface, consisting of several granules, in the 
Upper Cave of the Rhone Glacier, magnified 2°5 diam. 
Fig. 2 shows the surface of a large granule in the same cave, magnified 2°5 diam. 


Fig. 3 shows an enlargement of a portion of the surface of the granule in Fig. 2, 
enlarged to 10°8 diam. 


ViI.—Some Fossrz ANNELID Borrows.! 
By Dr. F, A. Barner, M.A., F.R.S. 


N the little note on ‘‘ Fossil Representatives of the Lithodomous 

Worm Polydora” which appeared in the GrotocicaL Magazine 

for March, 1909 (pp. 108-10), it is said that, ‘‘so far as I can 

ascertain, this genus has not hitherto been recorded in a fossil state.” 

It has since come to my knowledge that I was not the first so to 

record it, and I therefore ask permission to make the necessary 
emendation. 

In March, 1908 (Buil. Soc. géol. France, ser. 4, vol. vil, pp. 361-70, 
pl. xii), Professor Henri Douvillé published a paper on ‘‘ Perforations 
d’Annélides’”’, in which he figured a surface of Jurassic rock, from 
near the fort of Arrabida in Portugal, penetrated by burrows 
characteristic of Polydora. Since these Jurassic rocks are covered 
by others of Helvetian age, the borings cannot be of later date than 
Middle Miocene. These perforations, which were first observed by 
Mr. P. Choffat (December, 1906, Bull. Soc. géol. France, ser. 4, vol. vi, 
p- 237), are about twice as large as those of Polydora ciliata, and are 
therefore compared by Professor Douvillé with those of P. hoplura 
Claparéde. He adds: ‘On pourrait réserver a ces perforations la 
terminaison ztes et les désigner sous le nom de Polydorites.”’ Since no 
distinction can be drawn between the borings thus named Polydorites 
and those made by Polydora, it appears that ‘ Polydorites’ is not 
intended as an independent generic name, but merely as a brief way of 
writing ‘fossil traces of Polydora’. 

Polydora hoplura is a British species, though not so common as 
P. ciliata. Others placed in the British list by Professor W. C. 
M‘Intosh (February, 1909, Ann. Mag. Nat. Hist., ser. 8, vol. iii, 


1 Published by permission of the Trustees of the British Museum. 


Grout. Mae. 1910. 


Striations on Glacier Granules. 


Puate XIII. 


— 
a cater 
‘ie © 


Bemrose, Collo. 


Dr. F. A. Bather—Fossil Annelid Burrovs. ts 


pp. 169-74) are P. caeca Oersted, P. flava Claparéde, P. cf. quadrilobata 
Jacobi, and P. Carazzi n.sp. 

Professor Douvillé is inclined to refer to an annelid of the same 
Family (Spionide) some U-shaped galleries described by Professor 
Carlos I. Lisson (19041) under the name Tigillites Habichi n.sp. 
These occur in stratified quartzites around Chorillos, south of Lima 
(Peru), and are assigned by Professor Lisson to a post-Neocomian but 
pre-Tertiary age, because the quartzites are covered (though not quite 
conformably) by nodular and vari-coloured quartzites containing 
ammonites which he refers to Sonneratia. Mr. G. C. Crick does not 
consider that the figures and descriptions warrant this reference, and 
he inclines to agree with Mr. W. M. Gabb, who regarded the 
ammonite described by himself from this horizon as of Kimmeridgian 
or Corallian age. However this may be, Professor Douvillé seems 
to have made a slip in calling these rocks ‘‘ quartzites paléozoiques 
des environs de Callao.”’ 

While it seems probable that these tubes are not congeneric with 
the somewhat larger paleozoic Zigillites, there are objections to 
classing them with the smaller Polydora. The latter annelid makes 
littoral or inter-tidal borings into the hardened rocks of the shore. 
The tubes of 7. Habichi, on the other hand, were formed in soft sand, 
part passu with its deposition, a fact clearly indicated by their upward 
passage through successive laminz, and the successive withdrawals of 
the curved bottom of the U to a higher level. The mere fact that 
weathering occasionally reduces the double opening of the tube to 
a single more or less keyhole-shaped opening, as in Polydora, is not 
enough to outweigh these differences. 

That a keyhole-shaped opening is not in itself sufficient evidence of 
the work of Polydora follows from the studies of Dr. D. Carazzi 
on ‘‘La perforazione delle rocce calcaree per opera dei. datteri 
(Lithodomus dactylus)” (1892, Atti Soc. Ligustica, ii, pp. 279-97), 
where it is shown that the aperture of the burrow, at first circular, 
soon assumes an elliptical outline, which eventually becomes con- 
stricted along the minor axis, until the shape is almost that of an 8, 
with one half smaller than the other. The fragment of bored rock- 
surface, as figured by Dr. Carazzi on a reduced scale (p. 293), forcibly 
recalls the traces of Polydora. But the burrows have no septum 
to give them a U-shape, and their natural size (to judge from specimens 
in the British Museum) is about half-an-inch along the major axis. 

Professor Douvillé, accepting the views expressed by Mr. Clifton J. 
Sarle in February, 1906,” proceeds to discuss some forms hitherto 
referred to TZuonurus. Mr. Sarle came to the conclusion that 
Arthrophycus Hall, Dedalus Rouault (= Veaillum Rouault), Zaonurus 
Fischer-Ooster (= Spirophyton Hall, Alectorurus Schimper, Physophycus 
Schimper, Cancellophycus Saporta, Glossophycus Saporta & Marion) 
were traces of burrows formed by sedentary Polycheta in rather 


1 «Tos Tigillites del Salto del Fraile y algunas Sonneratia del Morro Solar : 
contribucién 4 la geologia de los alrededores de Lima,’’ Bol. Cuerpo Ingen. de Minas 
Pera, No. 17, 64 pp. Lima, 1904. 

2 «< Arthrophycus and Deedalus of Burrow Origin,”’ pp. 203-10 ; and ‘‘ Prel. Note 
on the Nature of Taonurus’’, pp. 211-4: Proc. Rochester Acad. Sci. iv. 


116 Dr. F. A. Bather—fossil Annelid Burrovws. 


loose sedimentary rock of various ages. He also referred to Zaonurus 
some traces previously placed under TZaonichnites (DMedusichnites) 
Matthew and Zoophycos Massalongo. And with all these forms he 
compared Dietyodora lebeana Weiss, Arenicolites duplex Williams, 
and Rhizocorallium Zenker (= Glossifungites Lomnicki). As regards 
the last-mentioned genus, to which he referred forms included under 
Taonurus by Saporta and others, Mr. Sarle wrote that they ‘‘ were 
produced by the packing of sediment along the radial side of 
a reclining U-shaped burrow of two openings, as it was repeatedly 
shifted and lengthened’’. The forms discussed by Professor Douvillé 
are Zaonurus ultimus Saporta & Marion, Miocene, 7. Panescorser 
Saporta and Marion, Trias, Z. Saportai Dewalque, Senonian. The 
last-mentioned, at all events, occurs on the worn surface of the 
Chalk,-and the burrows are filled with silica and glauconite from 
the overlying Landenian. Professor Douvillé regards the burrows 
as hollowed by a Spionid of large size living in the Lower Eocene 
sea. On account of their form he separates them from Zaonurus, 
and adopts the name Glossifungites Lomnicki (1886, Sprawozd.Kom. 
fizyjog. Akad.Umief.Krakowie, xx, p. (99), pl. iu, f. 64) of which 
the genotype is G. saxicava of Miocene age. If, however, this 
last is really the same as Rhizocorallium Zenker (1836, ‘‘ Historisch— 
topogr. Taschenb. v. Jena”, pp. 202-19), then that name must be 
preferred. The genetype is 2. jyenense Zenker (loce. citt.) occurring 
at the base of a thin bed of dolomite in the Bunter Marls near Jena. 

A good account of the older literature bearing on these curious 
forms will be found in the well-known memoir by S. Squinabol, 
‘‘Alghe e Pseudoalghe fossili italiene”’ (1890, Atti Soc. Ligustica, 1, 
pp. 29-49, 166-99). Most of them have generally been referred 
to a supposed Family of Algs, the Alectoruride. These have 
previously been discussed by Professor Th. Fuchs, who has recently 
accepted the views of Sarle and Douvillé (December, 1909, Mitt. 
Geol. Ges. Wien, li, pp. 335-50) and has extended a similar 
explanation to such forms as Vexillum Morrert Sap., V. Rouviller 
Sap. (= Phycodes cireinnatus Richter), V. Desglandi Rouault, 
Chondrites flabellaris Sap., and C. affinis Sternb. In short, it 
seems probable that a large number of forms previously placed by 
geologists in a convenient receptacle labelled ‘Fucoids’ may now 
be safely regarded as due to burrowing annelids. I am not, however, 
prepared as yet to agree with Professor Douvillé that those annelids 
belonged to the family Spionide. 

Mr. Linsdall Richardson, who discovered in the Rheetic conglomerate 
the bored pebble described in my previous note, seems subsequently to 
have found further examples, for he says in a report of an ‘‘ Excursion 
to the Frome District, Somerset”? (October, 1909, Proc. Geol. Assoc., 
XXi, on p. 223), that the conglomerate contains ‘ pebbles of chert and 
Carboniferous Limestone that were well bored by the Lithodomous 
Polydora ciliata (Johnston)”’. I must repeat my opinion that, " uhe 
worm .. . may well have been a Polydora, but it was not P. ciliata” 


Professor E. J. Garwood— Horizon of Archeosigillaria. 117 


VIJ.—On tur Horizon or tHE Lower CarsonirErous BrEps con- 
TAINING A RCW.EOSIGILLARIA VANUXEMI (GOppERT) Av Mearnop FELL. 
By Professor E. J. Garwoov, M.A., Sec. Geol. Soc. 


Fr a note on Archeosigillaria Vanuxemi and Bothrodendron sp., 

published in the Gxonoeican Magazine for February last, 
Mr. J. W. Jackson speculated on the age of the beds at Meathop, 
in which these plant remains occur, and refers to the general 
classification of the Lower Carboniferous rocks of the Westmorland 
district, which I gave in this magazine in 1907.' He remarks: ‘‘ It 
is perhaps premature to attempt to fix definitely the exact horizon of 
these beds, as they appear to have been as yet but superficially 
studied.” * Since the classification above referred to was published, 
I have devoted such time as could be spared from professional duties 
to an exhaustive examination of the whole northern area, the result 
of which has been to confirm the general conclusions already given in 
this magazine. In my forthcoming account of the district, I have 
given a detailed description of the. Meathop section. ‘The delay in 
publishing a full account of the northern area has been necessitated 
by the general structure of the district, which required a careful 
study of isolated outcrops, extending over a very large area, before an 
accurate co-ordination of the separate exposures could be established. 
If any justification for this delay were needed, it is supplied by 
Mr. Jackson’s note, in which he confesses his inability to decide upon 
the age of the beds displayed in the isolated exposure at Meathop on 
the evidence afforded by the collections obtained during his visits to 
that locality. 

On my iirst visit to this section some years ago I obtained only 
a scanty fauna, giving inconclusive evidence of the horizon, and it has 
required very careful and close collecting during repeated visits 
before the beds could be definitely correlated with those occurring in 
other portions of the district where the horizons could be accurately 
determined. Pending the publication of my detailed description it 
may therefore be of interest to give here the conclusions arrived at 
regarding the age of the Meathop beds and the evidence upon which 
it is based. 

My further work in the district since the provisional classification 
was published proved conclusively that the Meathop beds were 
correctly correlated with the lower dolomites of Shap and Brigsteer, 
and represent the lower portion of Dr. Vaughan’s C horizon in the 
Bristol area. ‘This is clearly shown by a comparison of the Meathop 
fauna with that of the beds in the Shap exposures. In my previous 
notes I laid emphasis on the importance of the Arnside Michelinia 
bed as furnishing a definite horizon in the northern sequence, and 
regretted the absence of beds containing this characteristic fauna from 
the Shap district. At the same time I gave evidence in support of 
the contention that the IWichelinia megastoma bed must be represented 
in that district by the base of the Ashfell Sandstone, or by the top of 
the Shap dolomite. This contention has now been fully corroborated 
by the finding of Mchelinia itself in the Camarophoria isorhyncha 


1 Gror. Mac., 1907, Dec. V, Vol. IV, pp. 70-4. 2 See table, op. cit., p. 73. 


118 Professor FE. J. Garwood—Horizon of Archeosigillaria. 


bed in the lowest layer of the Ashfell Sandstone of the Shap area; 
the further interesting discovery two years ago of Michelinia megastoma 
with Camarophoria isorhyncha on the summit of Meathop Fell no 
longer leaves any reasonable doubt as to the horizon to which these 
beds belong. 

Mr. Jackson mentions the occurrence of Spirifer ef. furcatus 
(McCoy) and Productus aff. corrugatus (McCoy) in addition to the 
forms already given in my original account of the beds. This Spirifer 
bed forms a well-marked horizon along the top of the old quarries 
on both sides of Meathop Fell, and these two fossils are always 
found at this horizon in the district, together with the other character- 
istic species (given below). Mr. Jackson also states that he collected 
Retieularia aff. lineata (Martin) from this Spirifer bed. This state- 
ment, if corroborated, is decidedly important, as I have never found 
this species in the northern area below the horizon D 2-D3. It is 
possible, however, that Mr. Jackson may be mistaken in his identi- 
fication. Numerous examples of Athyris glabistria also occur at this 
horizon, and as the shells are badly preserved and often fragmentary 
an accurate determination is not always possible. My collections 
from the Spirifer bed at Meathop contain several other species not 
previously recorded, the majority of which also occur in the cor- 
responding horizon in the Shap area. ‘The following is a list of 
forms found in both localities, and shows the close parallelism of 
the deposits :— 


Michelinia megastoma. Productus cf. corrugato-hemisphericus. 
Camarophoria isorhyncha. P. cf. pustulosus. 

Syringothyris cuspidata. Orthotetes crenistria (C 1 var.). 
Spirifer cf. furcatus. Euomphatus. 

Athyris glabistria. Archeosigillaria Vanuxemi (Goppert). 
Derbya sp. Bellerophon sp. 


Seminula gregaria, McCoy. 


In addition to these characteristic forms several interesting corals 
occur which are described in detail in my forthcoming paper. 

The beds underlying the Sprrifer bed at Meathop also contain forms 
which occur in a similar position below the Zsorhyncha bed in the 
Shap area and confirm the correlation here given. It will be 
sufficient here to mention the occurrence in the lowest beds at 
Meathop of Humetria proava (Phil.) and Solenopora sp., which I have 
found to characterize the lower portion of the C 1 horizon wherever 
these beds are exposed in the northern area. 

With regard to the plant remains of Meathop, and elsewhere in 
Westmorland, they are the rule rather than the exception in these 
lower beds, and may occur at any horizon which happens to be 
locally near the base of Carboniferous formation wherever the beds 
were deposited in proximity to a subsiding land surface. Thus they 
occur near the local base at Meathop, Shap Abbey, Shap Toll Bar, 
Pinkskey Gill, Hebblethwaite Gill, near Horton-in-Ribblesdale and 
elsewhere. 

Mr. Jackson suggests that 4. Vanuxemi ‘may be helpful in 
arriving at a satisfactory conclusion as to the correct horizon” of the 
beds which contain it, and adds, ‘‘ especially when the exact horizon 


Notices of Memoirs—S.W. Highlands of Scotland. 119 


of the plant is known in the North Wales Exposure.” I am afraid 
that I cannot agree with this suggestion; on the contrary I think 
that any conclusion, based on the occurrence of isolated fragments of 
plant-remains in the Lower Carboniferous rocks might be most 
misleading, and might result in serious errors in correlation. 

Thus in the present instance 4A. Vanuxemi occurs at Meathop and 
at two horizons in the Shap district in beds which, as I have shown, 
belong to the C 1 horizon of the Bristol area, while in North Wales 
abundant remains of this species occur according to Messrs. Hind and 
Stobbs in S 2, an horizon very much higher in the series; lastly, this 
species was originally described from the Upper Devonian of New 
York. After all, this is only in keeping with what we have been led 
to expect from the study of the relative duration of terrigenous and 
marine floras and faunas elsewhere, for instance the Laramie and 
overlying formations in America. 


NOTICES OF MBEMOTRS. 


Prozsiems or THE Sovrn-Western Hicuianps or Scornanp. Abstract 
of the Presidential Address to the Glasgow Geological Society by 
Professor J. W. Grecory, D.Sc., F.R.S., F.G.S., January, 1910. 

f¥VHE Southern Highlands of Scotland consist of a complex series of 

eneisses, schists, crystalline limestones and quartzites, trending 
across Scotland approximately from south-west to north-east. These 
metamorphic rocks are bounded abruptly to the south by the Highland 

Boundary Fault, which brings them against Upper Palzeozoic rocks. 

Their northern boundary is less regular and is generally the junction 

with the Moine Gneiss, the rock which occupies so much of the 

Northern and Central Highlands. The schists and the associated 

rocks between the Moine Gneiss and the Boundary Fault may 

be conveniently grouped together, under the name proposed by 

Sir Archibald Geikie, as the Dalradian System. 

The most important difficulty in the interpretation of these rocks is 
the uncertainty as to which is the upper and which the lower end of 
the succession. According to Nicol, the southern members are the 
youngest, and there is a descending series to the north. This view is 
contradicted by many obvious facts in the field geology; the view is 
therefore widely held that Nicol’s order must be reversed and that the 
beds on the southern margin are the oldest. ‘The serious difficulty in 
the second view is that the southern rocks are much less altered than 
the northern, and this theory therefore involves some measure of 
selective metamorphism. Several ingenious interpretations have been 
advanced to overcome this difficulty. The author of the address, 
however, held that both views as to the order of the succession are 
correct in parts. 

The Dalradian System is intermediate in age between the Torridon 
Sandstone above and the Caledonian and Lewisian Gneisses below. 
That it is pre-Torridonian seems to follow from the evidence in Islay 
and Colonsay; that it is post-Caledonian is shown by its superposition 
upon the Moine Gneiss in several localities, as north of Ben Lui and in 
Glen Tilt; in the latter, the evidence collected by Mr. Barrow appears 


120 Notices of Memoirs—Professor J. W. Gregory— 


conclusive that the Dalradians are resting on an eroded surface of the 
Moine Gneiss. The Dalradian System may be divided into five series 
as follows :— . 


Schiehallion Quartzite Series (including the Boulder Bed). 

Blair Atholl Series (Limestones, black schists and quartzites). 

Ben Lawers Series (Phyllites with some limestones and quartzites). 

Loch Tay Series (Limestones, garnetiferous mica schists and 
some quartzites). 

Loch Lomond Series (Gneiss, albite schist, etc.). 


The most important rock in the lowest series is the Loch Lomond 
Gneiss, which is well developed in the peninsula of Cowal, on both 
sides of the northern part of Loch Lomond, and around Loch Katrine. 
This series consists mainly of coarse, highly inclined sedimentary 
gneiss and albite schists. This series extends eastward to Loch Voil, 
where it disappears beneath the rocks of the Loch Tay Series to the 
north and the overlap of the Ben Ledi and Ben Vane Grits and slates 
to the south. North of the Loch Lomond Gneiss occurs a series of 
garnetiferous mica schists associated with limestones and some 
quartzites. This series can be traced all across the country; it 
includes the Glen Daruel limestone south of Loch Fyne, and the 
limestones of Crianlarich, Glen Lyon, and Loch Tay. That they 
overlie the Loch Lomond Series is well shown north of Loch Voil, 
and that they rest unconformably on the Moine Gneiss is proved by 
the evidence north of Ben Lui. The essential member of the Ben 
Lawers Series is the phyllite of Ardrishaig, the Forest of Mamlorn 
and Ben Lawers. This phyllite is often intensely crumpled and 
seamed with innumerable thin quartz veins. It is associated with 
thin bands of quartzite and quartz-schist. Its superposition on the 
Loch Tay series appears to be clearly demonstrated from the relations 
of the two series at Ben Lawers, and still more clearly from the 
outliers of the Ben Lawers phyllite resting upon garnetiferous mica 
schists, as at Ben nam Imirean. 

The Blair Atholl Series consists of the Blair Atholl Limestones, the 
black or graphitic schists and some interbedded quartzites, which are 
often of considerable thickness and form a large part of the Highland 
Quartzite. To separate them from the succeeding quartzite, it is 
proposed to call them the Cammock Hill Quartzite, from a locality 
where they are well exposed near Pitlochry. 

_ The uppermost member of the Dalradian System is the Schiehallion 
Quartzite with the boulder bed at its base. It rests unconformably 
upon the Blair Atholl Series. Parts of the quartzite are quite 
unfoliated and remain as granular felspathic quartzites, in which the 
felspar grains have not been sheared or crushed. 

According to this arrangement, the five series of the main Dalradian 
sequence occur in succession from south to north, and the oldest 
members are the most altered and highly crystalline. 

Along the southern margin of the Dalradian schists there is a series 
of slates and grits, which are not foliated, and strikingly resemble 
ordinary Paleozoic slates and quartzites. The slates are worked at 
Luss and Aberfoil. The field relations of these Aberfoil Slates and 


Problems of S.W. Highlands of Scotland. 121 


Ben Ledi Grits can be most easily explained by their unconformable 
deposition on the southern edge of the Dalradian rocks. 

There has been assumed a transition from the Ben Ledi Grits to the 
intensely altered gneissic grits belonging to the Loch Lomond series, 
but the evidence for this passage is not convincing. The southernmost 
part of these comparatively unaltered rocks include cherts and shales 
which are marked on the Survey Maps as ‘Silurian(?)’.!. The exact 
age of these beds is doubtful. They may be Upper Dalradian and 
correspond to the great unconformity at the base of the Schiehallion 
Quartzites, or, as is more probable, they may be post-Dalradian in age. 

The relations of the Dalradian Schists is suggested as follows:— 

Algonkian . . . Torridon Sandstone. 


Honbic Dalradian. 
; Caledonian . . . Moine Gneiss and associated schists, 
Lewisian . ». » Fundamental Gneiss. 


The classification suggested in the address adopts Nicol’s succession 
in part, as it accepts the Aberfoil and Ben Ledi Series as younger 
than the Loch Lomond Gneiss against which they rest; and it is 
consistent with the less altered condition of the southern rocks and the 
steady diminution in the metamorphism of the rest of the series going 
northward, as for example, from the Loch Lomond Gneiss to the Loch 
Awe Grits, and from the garnetiferous mica schists of the Loch Tay 
Series to the black schists and unfoliated quartzites near Blair Atholl. 

The evidence in some points of this succession is still incomplete, 
especially as regards some of the rocks nearest Glasgow. The special 
problems on which further research would be most useful were 
therefore mentioned, in the hope that the members of the Glasgow 
Geological Society would investigate them. 

The subject is of interest from its bearing upon the early geological 
history and geography of North-Western Europe. The structure of 
Western Europe has been dominated by the formation of three great 
mountain systems, each due to pressure usually from the south, and 
each haying its younger rocks exposed mainly on the northern flanks of 
the chain. The youngest is the Alpine System, formed mainly in Upper 
Cainozoic times, and including the Pyrenees, Alps, Carpathians, ete. 
A somewhat similar mountain system, of which fragments remain in 
Southern Ireland, Devonshire, Brittany and Germany had been formed 
in Upper Paleozoic times; from its analogy with the Altai Mountains 
of Asia, Suess has called its mountains the European Altaids. Still 
earlier, in later Archean times, there was formed the first of these 
European mountain systems, of which fragments occur in Northern 
Treland, the Grampians, and Scandinavia. There are many interesting 
analogies between these old Grampians and the later Altaids and Alps. 
The old mountain system to which the Grampians belonged probably 
extended far westward into the North Atlantic and to its influence 
may be attributed the desert climate of Scotland during the deposition 
of the Torridon Sandstone. 


1 By kind permission of Dr. Horne it was announced during the address that 
Dr. Hinde has recently identified Radiolaria in the cherts of this series. 


122 Reviews—Professor Joly’s Radioactivity and Geology. 


RAVIEWwS. 


LAY PTE S 

I.—Rapioactivity anp Grotocy: an Account oF THE INFLUENCE OF 
Raproactive Enrercy on Terrresrrrat History. By J. Jony, 
M.A., Sc.D., F.R.S. 8vo; pp. xi+287. London: A. Constable 
and Co., Ltd., 1909. Price 7s. 6d. 


(J\HE aorelo acme which have followed so rapidly upon the dicayeee 
i} of the wonderful properties of radium have caused something like 
a revolution in more than one branch of physical science. How much 
these new developments concern geologists was first brought home to 
most of us by Professor Joly’s address at the Dublin meeting of the 
British Association in 1908. The yolume before us is an expansion of 
that address. In it the author marshals the results of researches, to 
which he has largely contributed, concerning the distribution of radium 
in igneous rocks, in sediments of different kinds, and in various waters. 
From the results thus brought together he deduces consequences of 
great moment, which are pursued, in successive chapters of the book, 
through all the ramifications of dynamic geology. 

The variety of subjects which are passed in review, and the fact 
that they are presented as parts of an organic whole, make it difficult 
to do justice to Professor Joly’s work in a brief notice. Indeed, it is 
scarcely possible to summarize what is in effect one extended chain of 
arguments resting on numerical data. It makes us see from a new 
point of view the “complex interaction which unites the varied opera- 
tions of inorganic nature. We are familiar, for instance, with the 
conception of a cycle of events: sedimentation leading to gradual 
subsidence of an area under the growing load, the heating of 
the depressed rock-masses causing upheaval and folding, finally 
erosion coming into play, with transportation and renewed sedimenta- 
tion in an area adjacent to the former. Viewed in the light of the 
radium-content of the sediments, this assumes a new aspect. ‘‘ The 
energy . . . is in fact transported with the sediments—the energy 
which determines the place of yielding and upheaval, and ordains 
that the mountain ranges shall stand around the continental borders. 
Sedimentation from this point of view is a convection of energy” 
(chap. v). In the following chapter the author endeavours to trace 
a like relation between the instability of the ocean floor and the radio- 
activity of oceanic deposits. 

In a book treating of a field so wide and so little explored there is 
necessarily much which must be regarded as debatable. That the 
radioactive processes are not controlled by temperature or pressure is 
a thesis so remarkable that we are entitled to ask for very cogent 
evidence of it. Some experimental data bearing on this point are 
cited, but they do not apply to the breaking up of the parent 
uranium, upon which the whole train of transformations depends. 
If we can suppose this process to be checked by rise of temperature, 
Professor Joly’s argument concerning the relation of underground 
temperature to radioactivity will require revision. It will be no 
longer necessary to assume that the heavy element uranium is 
accumulated in the outer layer of the globe, an arrangement which 
the author explains in a manner not very conyincing. 


Reviews—Professor Joly’s Radioactivity and Geology. 128 


Many readers will turn expectant to the chapter on ‘‘ Uranium and 
the Age of the Earth’’; but here we must confess some degree of 
disappointment. From comparative determinations of radium and 
helium, especially in phosphatic nodules,! Strutt has arrived at high 
estimates of the age of the stratified sequence. Since the most hkely 
source of error is loss of part of the helium, these should be under- 
rather than over-estimates. Our author cites these and some other 
results, but only to emphasize the elements of doubt attaching to 
them. He then throws over radioactivity, and offers us, instead, two 
methods of calculating geological time which lead to very much lower 
figures. One is based on the rate of sedimentation, and the other on 
the amount of sodium in the sea. Both have already been before the 
geological public, and it is not necessary to enter into them. To us 
they appear far more hazardous than the helium method. 

The manipulation of figures possesses an undoubted fascination. 
There is a feeling of security in striking a mean of discordant results, 
and a certain sense of generosity in allowing a margin on the side of 
safety; and it is easy for the enthusiastic speculator to forget how 
enormously errors may accumulate when several rough estimates are 
taken as links in a chain of argument. Even the taking of a mean 
demands more judgment than it sometimes receives. For instance, on 
p. 284 of this book, we are given the ratio of sediment carried in the 
waters of nine different rivers. ‘his ratio ranges from 1 in 291 to 
1in 10,000. We do not believe that an average of nine figures so 
discordant can afford any useful information concerning the average 
amount of sediment carried by the rivers of the world. But, further, 
the author has taken a harmonic instead of an arithmetic mean. The 
true mean is not 1 in 2781, but 1 in 1182, which at one blow reduces 
the calculated eighty millions of years to about thirty-five millions ! 
Personally we do not attach any weight to one or other of these 
figures. 

We are far from wishing to disparage the introduction of quanti- 
tative considerations into dynamical and historical geology; but we 
feel at the same time the need for sounding a note of warning at the 
present juncture. Thanks to the discovery of radium, geology -is 
finally delivered from the tyranny of a certain school of physicists, 
and Lord Kelvin’s arguments based upon the consistentior status are 
swept away. Let us take heed lest, freed from one bondage, we fall 
straightway into another not less galling. 

Probably Professor Joly does not look for unhesitating acceptance 
of all his conclusions. However much opinions may differ on some 
of the points raised, he has here introduced us to a large number of 
important and curious questions, and his book should be in the hands 
of every geologist who is interested in the modern developments ot 
science. 


A. H. 


_ | Strongly confirmed, since this was written, by examination of zircons from 
igneous rocks of various ages. 


124 Reviews—Geologists’ Association—Geology in the Field. 


Il.—Grotocy in vHE Fiecp. Tue Jositer Volume oF THE 
GroLocists’ Association (1858-1908). Edited by H. W. 
Moncxron and R. S. Herries. Part Il: pp. 210-432, with 
8 plates. London: Edward Stanford. 1910. Price 5s. net. 

N December last we drew attention to the publication of Part I of 

this work, and we are glad to note that a copious index is 
promised at the conclusion of the fourth part. The work is a more 
or less complex one, dealing sometimes with the geology of particular 
counties, at others with irregular districts, and again with particular 
formations in certain areas. The whole has been most carefully 
edited by Messrs. Monckton and Herries, whose task must have been 
no light one. The records of previous excursions made by the 

Geologists’ Association form the basis of the work, and there are 

abundant references to the published proceedings, although the 

names of the responsible directors of excursions are not always 
indicated. 

In the present part, ‘‘ Berkshire and part of the Thames Valley ” 
forms the subject of an article by Mr. H. J. Osborne White. He deals 
with strata from the Oxfordian to the Alluvial deposits. A useful 
sketch-map is given of the neighbourhood of Faringdon, showing the 
position of the pits in the famous sponge-gravel beds of the Lower 
Greensand. 

‘North Kent and adjoining parts of Surrey” are next described by 
Mr. A. L. Leach, who, after a brief reference to the Chalk, the 
Chislehurst Caves and Dene-holes, describes the principal sections in 
the Eocene strata, notes the Pliocene Beds of Lenham and elsewhere, 
and concludes with a short account of the superficial deposits and 
successive types of stone-implements. 

““The Chalk Cliffs of Kent and Sussex and the Tertiary Beds of 
Herne Bay”’ are described by Mr. G. W. Young, with due references 
to the labours of Mr. Whitaker and Dr. Rowe, in whose footsteps 
Mr. Young has so successfully trodden. 

«The Tertiary and Post-Tertiary Deposits of the Sussex Coast” 
are dealt with by Mr. J. V. Elsden. Newhaven, Bognor, and Selsey 
Bill come in for notice in connexion with the Eocene strata, while the 
Coombe Rock and other superficial deposits are discussed. The author 
remarks that the bottom of the Arun Valley is now considerably below 
sea-level. 

‘‘Hampshire and the Bagshot District’ come into the appropriate 
hands of Mr. Monckton and Mr. Osborne White, who deal with the 
Chalk and Kocene, and especially with the Bagshot, Bracklesham, and 
Barton Beds. 

‘“‘ Wiltshire ”’ is described by Mr. H. B. Woodward, who gives brief 
accounts of the famous sections in strata that range from Lias to 
Purbeck and Wealden, and from Lower Greensand to Chalk and 
Eocene, with superficial deposits of much interest. Reference is 
made to Mr. Harmer’s ‘ Glacial Lake’ in the Trowbridge Basin. 

‘The Paleozoic Rocks of Gloucestershire and Somerset’? form the 
subject of an article by Professor 8. H. Reynolds, who has added so 
much to our knowledge of the Tortworth Silurian area, and has 
discovered fossiliferous strata, probably of Llandovery age on the 


Reviews—Prof. H. 8S. Goodrich—Cyclostomes and Fishes. 125 


Mendips. The associated volcanic rocks, the Old Red Sandstone and 
its fish-remains, and the zones in the Carboniferous Limestone Series 
are more particularly described, brief references only being made to 
the Coal-measures. 

“The Neozoic Rocks of Gloucestershire and Somerset,’’ including 
accounts of various formations from the Bunter to the Chalk and 
superficial deposits, are described by Mr. L. Richardson. As might 
be expected more details are given of the Rhetic Beds, with their 
basal grey marls, termed Sully Beds, that have yielded <Avicula 
| Pteria| contorta and Ostrea Bristow: ; of the Lias and Inferior Oolite 
and their ‘hemere’. ‘he geological history after the Cretaceous 
Period is briefly sketched, and full references are given to the 
literature of the Drift deposits. 

‘« Dorset—Inland ” is the title of an article contributed by the late 
W. H. Hudleston, and it is prefaced by a list of names of fossils and 
zones adopted by him, with remarks upon them, drawn up at his 
request, by Mr. 8. 8. Buckman. We must confess to a preference for 
the names used by Mr. Hudleston, whose judgment on these matters 
was always philosophic, sound, and practical. ‘lhe principal sections 
in the Inferior Oolite near Sherborne and Yeovil are described ; and 
an account is given of the Wareham District, with particulars of the 
well-boring at Bovington, and of the outlier of possibly Bembridge 
Limestone, discovered by the author at Creechbarrow Hill. 

“The Dorset Coast’’ is described by Mr. Monckton, who deals 
with the strata visited during excursions made to Lyme Regis, 
Bridport, Weymouth, Abbotsbury, and the Isle of Purbeck. 

‘“«The Isle of Wight ” is dealt with by Mr. Herries, who has given 
a concise account of the physical features and geology of this oft- 
visited geological paradise. 

There is therefore plenty of interesting and instructive material to 
be found in this part of ‘‘Geology in the Field ”, and it will be of 
essential service to all who visit the districts described. 


III.—A Treartisz on Zootoey. Edited by Sir Ray Lanxesrur, K.C.B., 
Mave Du. S» . Part LX) Vertebrata: Craniata (First 
fascicle : Oyclostomes and Fishes), by E. S. Goopricu, M.A., 
F.R.S. London: Adam & Charles Black, 1909. 8vo; pp. SSeS, 
with 515 text-figures. Price 15s. 

FF\HIS volume, like the others of the series to which it belongs, is 

devoted to morphology and classification; it contains valuable 

and well-written accounts of the general characters of the Craniate 

Vertebrates, of the Cyclostomata and Gnathostomata, of the Fishes, 

and of the two main branches of the last-named, the Chondrichthyes 

and Osteichthyes; the results of Mr. Goodrich’s recent important 
researches on the exoskeletal structures of fishes and on the origin of 
limbs are here included. 

The morphological parts of the book suffer a little from com- 
pression, and from the paucity of references to function. The state- 
ment that the jaws developed from the first pair of visceral arches 
might have been qualified, for the labial cartilages may reasonably be 
interpreted as the remnants of pre- -mandibular arches. 


126 Reviews—Prof. EB. S. Goodrich—Cyclostomes and Fishes. 


The arrangement of the Selachians (Chondrichthyes) differs from 
most recent systems in the recognition of only four primary groups, 
the Holocephali and Euselachii (Selachii of Goodrich) being united to 
form a division co-ordinate with the Ichthyotomi, Pleuropterygii, and 
Acanthodii. In a natural system the two last-named should be placed 
first, the structure of their paired fins and the absence of mixopterygia 
indicating their generalization; of the other three orders, or sub- 
classes, characterized by the presence of mixopterygia, the Holo- 
cephali are quite as distinct from the Kuselachii as from the Ichthyo- 
tomi; the presence of a pharyngo-hyal shows that their autostyly is 
not a modified hyostyly, and Mr. Goodrich has failed to recognize 
that in the Selachians the terms ‘hyomandibular’ and ‘ epihyal’ are 
synonymous, and that the hyoid arch of the Chimeroids is essentially 
similar to the succeeding branchial arches. 

The classification of the modern Sharks and Rays is marred by 
some erroneous diagnoses and unnatural groupings; for example, the 
Jamnide are said to have no oro-nasal grooves, wide gill-openings, 
a pit at the base of the caudal fin and a keel on each side of the tail, 
and they are made to include Alopias, which has small gill-openings 
and no caudal keel, the Odontaspide, without or with vestigial pit 
and without keel, and Rhinodon, which differs from them 7 foto in 
the presence of oro-nasal grooves, the position of the gill-openings 
above the pectoral fin, etc., and indeed belongs to the Orectolobide, 
which family our author unites with the very different Scyliorhinidse 
(Seylliide). 

The Chondrichthyes are followed by the Ostracodermi, a provisional 
group; here some of Dr. Traquair’s recent interesting discoveries from 
the Silurian of Scotland are described and figured, and his views as to 
the relationship of the Ccelolepide, Psammosteide and Drepanaspidee 
are confirmed by Mr. Goodrich’s demonstration of the structural 
similarity of their exoskeleton. A new restoration of Cephalaspis calls 
for comment, as the organs shown by Dr. Smith Woodward to be 
‘ opercular’ prolongations of the head-shield, are figured and described 
as scaly, fin-like lobes, narrowed at the base, and projecting from each 
side of the body behind the head-shield; we venture to think that 
there is no justification for this interpretation. 

The Osteichthyes are divided into two main branches, the Dipnoi 
(with which the Arthrodires are provisionally associated), and the 
Teleostomi; it is not a little singular that this arrangement should be 
maintained by Mr. Goodrich, whose embryological researches have 
confirmed the secondary nature of the so-called ‘archipterygium’, and 
who first described the similar structure of. the Osteolepid and 
primitive Dipnoan scales and fin-rays, and the nearly normal arrange- 
ment of the bones of the cranial roof in Dipnoan genera such as 
Phaneropleuron and Ctenodus. 

The Dipnoi indeed scarcely differ from the Osteolepida except in 
their autostyly, and as this is plainly a modified hyostyly, from the 
structure of the hyoid arch, they should follow that group in a natural 
system. The modern Dipnoans are said to have internal nares, but 
as a matter of fact the nostrils are merely labial, as in some Eels” 
( Ophichthys), and the posterior ones cannot, be homologized with true 


Reviews—Prof. E. S. Goodrich—Cyclostomes and Fishes. 127 


internal nares. Mr. Goodrich thinks that the nostrils were ventral in 
the Osteolepida; this can scarcely have been the case in fishes with 
a terminal mouth and marginal dentition, and in which (as in 
Cricodus) the small nasal pits were antero-lateral. 

The Crossopterygii follow the Dipnoi, and lead through Polypterus 
to the Chondrostei; the highly specialized present-day members 
of the last-named croup still retain many features of generalization, 
notably in the paired fins, and they can be traced back step by step 
to the paleozoic Paleoniscide, in our opinion the most primitive 
of all Teleostomes, in which the pelvic fins had an extended base, 
and were supported, as in the modern Psephurus, by a series of 
parallel pterygiophores. Mr. Goodrich has shown that Polypterus 
agrees with the Paleoniscide in scale structure, and this confirms 
the evidence derived from the paired fins, that the recent genus 
is not descended from the Osteolepida, but from more generalized 
Crossopterygians. 

In the classification of the Mesozoic fiche’ of the Actinopterygian 
series Mr. Goodrich follows Dr. Smith Woodward, except that he 
makes the Amioids equivalent in rank to the Teleosts, and by placing 
the Oligopleuride and some allied families in the former renders 
neither group definable. The classification of the Teleosteans is 
based on that of the ‘‘Cambridge Natural History’’, but the best 
feature of that system, its simplicity, has been lost. A number 
of new, and often unnatural, divisions are established, many of which 
are merely designated Super-family I, Branch A, Sub-tribe B, etc., 
and when names are given they only confuse matters still more. 
Thus the Cypriniformes are a sub-order, the Lampridiformes a division, 
the Zeorhombiformes a subdivision, the Perciformes a tribe, and 
the Cheetodontiformes a sub-tribe, whilst the termination ozdez is 
also used for a number of groups of unequal rank. In addition to the 
Siganide (Teuthidide of Giinther) and the Acanthuride (Teuthidide 
of modern authors) a family Teuthidide is included and diagnosed 
which has no actual existence. ‘he interposition of the Plectognathi 
between closely related families such as the Serranide and Cen- 
trarchide, and of the Ostariophysi between the Leptolepide and 
Elopide, cannot easily be justified; it would be paralleled by the 
intercalation of the Marsupials between Ornithorhynchus and Echidna. 

The illustrations are numerous and on the whole well-executed. 
Mr. Goodrich’s original restorations of the crania of some extinct. 
Dipnoans, and his diagrammatic sections illustrating scale structures 
are especially interesting. One of the least satisfactory figures is that 
of the caudal fin of the cod, for it does not show that most of the rays, 
except the few attached to the reduced hypural, are inserted each on 
its own basal support; the latter are about twice as numerous as the 
neural and hzmal spines, with which about half of them are ankylosed, 
whilst the rest remain distinct or unite with the neural and hemal 
spines by suture. This structure, clearly seen in Gadus virens and 
G@. morrhua, is probably characteristic of all the Gadide. 

__ A useful bibliography concludes the book, which, on the whole, 
does not compare favourably with some of the others in this series; 
for whilst the general chapters reach the high level expected of 


128 Reviews—British Fossils and the Paleontographical Society. 


a zoologist of Mr. Goodrich’s reputation and experience, the systematic 
portions, in the case of some of the recent groups, indicate that he is 
not thoroughly acquainted with the animals about which he is writing. 


Cae 


IV.—Brrvisn Fosstts. Monographs of the Paleeontographical Society, ! 
1909, vol. 1xiii. 
‘{\HE beautifully illustrated works on British fossils published by 
the Palzontographical Society still appear with their wonted 
regularity. There is no lack of valuable material, and paleontologists 
who have opportunity for pursuing extended researches are glad to 
avail themselves of the facilities for the adequate illustration of their 
writings afforded by the Society. It is only to be regretted that the 
annual volume shows a tendency to reduction in size, owing to the 
recent death of numerous old. subscribers and the tardiness of the new 
generation in taking their places. 

The volume for 1909 opens with another instalment of the 
Monograph of British Pleistocene Mammalia by Professor 8. H. 
Reynolds. This year he deals with the Canide, and publishes a fine 
series of illustrations of the skulls and teeth of the wolf, Arctic fox, 
and common fox. ‘The text is disappointing and scarcely does 
justice to the subject; but the measurements and drawings will be 
very useful to collectors for identification of their specimens. 
Dr. A. 8S. Woodward follows with the fifth part of his Fossil Fishes 
of the English Chalk, treating of the Ganoids (except Protosphyrena 
and Belonostomus, which were described in the previous year). Some 
of the remains are very fragmentary and hardly worth description ; 
but the unique collection of Macropoma from the English Chalk has 
afforded the opportunity for a valuable new contribution to our 
knowledge of the Ceelacanthide. A drawing of the restored skeleton 
of Macropoma, by Miss G. M. Woodward, is included. Dr. Traquair 
contributes another instalment of his important memoir on the 
Carboniferous Palzoniscid Fishes, with a fine series of plates. He 
writes chiefly of Acrolepis and Nematoptychius, and adds drawings of 
Lhadinichthys, which are presumably to be described in the next part. 
Acrolepis Hopkinst appears to occur above and below the Millstone 
Grit—an unusually extended distribution. Mr. Henry Woods provides 
the largest section of the volume in another part of his well-known 
Monograph of Cretaceous Lamellibranchia, which makes excellent 
progress. This year he deals with the . Solenide, Saxicavide, 
Pholadide, Teredinide, Anatinide, Pholadomyide, Pleuromyidee, 
Poromyacide, and Cuspidaride. It is a most laborious work, on 
account of the extensive literature which has to be digested while 
the fossils are studied; but it is evidently done with thoroughness. 
The volume concludes with title-pages and indexes for Sharp’s 
Mollusca of the Chalk and Phillips’ British Belemnites, which were 
left unfinished by the death of the authors. many years ago. 


1 Annual subscription, which entitles to membership, £1 1s., due January 1. 
Apply to the Secretary, Dr. A.S. Woodward, F.R.S., British Museum (Nat. Hist.). 


Reviews—Brief Notices. 129 


V.—Brier Notices. 

1. Sorts. oF Sourn Arrica.—Dr. C. F. Juritz, in his Presidential 
Address to Section 2 of the South African Association for the 
Advancement of Science, on September 29, 1909, has some pertinent 
remarks on this subject. After sketching the general lines of soil 
investigation, he states: ‘‘ We have not been able to do all this in the 
Cape Colony, because the entire work of investigating the Colony’s 
soils has always been allocated to one solitary man, and even then it 
has been subject to constant interruption.” He proceeds to point out 
what is done in the United States, and shows that the original staff of 
10 men (not one man) had, ten years after its establishment, increased 
to 127 men, including 83 scientists and soil experts, 13 tobacco 
experts, and 29 clerks and other employés, and still was found 
inadequate for one-half the demands made upon it for investigations 
along its special lines. Dr. Juritz, quoting the official publications, 
points out that extraordinary increases in land value have followed 
the work of the Bureau of Soils in the United States. Soils in the 
Connecticut Valley, which the Bureau showed were adapted for 
growing a superior tobacco, increased in value threefold. Trucking 
soils of the Atlantic seaboard have risen from 5 dollars an acre to 
200 dollars; rice lands of Louisiana from 5 to 50 dollars; and 
Florida patches, specially adapted for growing pine-apples, from 
nothing to over 500 dollars an acre. Upon these facts and many 
others Dr. Juritz comments: ‘‘Has not the time arrived for this 
important subject to be tackled in right earnest in our own South 
Africa instead of continuing merely to be toyed with?” 

2. Sorrs or Huneary.—For many years the study of the soils of 
Hungary has occupied a number of her best investigators, and in 
February last year the Royal Hungarian Geological Institute (Ilagyar 
kiralyi Féldtant Intezet) issued invitations for a Conference of Agro- 
geologists to meet in Budapest. This was, we believe, the first 
Agrogeological Congress, and the report of its deliberations is now 
before us as Comptes Fendus de la premiere Conférence Internationale 
Agrogéologique. The volume consists of 334 pages and has a soil map 
of Roumania with an inset map of the climatic zones of the same 
country. Sixty-nine pages are devoted to the reports of the meetings 
of the Congress, twenty to the excursions made to Hidegkut, Godollo, 
the Great Plain (Alfold), and to Lake Balaton; and the remainder of 
the volume is occupied by papers on various subjects as follows :— 
Soils of Kuropean and Asiatic Russia, by Glinka; Soils of Norway, by 
Bjorlykke ; Daily Weathering in the light of Colloidal Chemistry, by 
Cornu; What is Weathering? by Treitz; Climatic Zones of Soils, 
by Cholnoky; Special Exigences of Agriculture with regard to 
Analyses of Soils, by Leplae; Methods of Soil Analysis in the 
Prussian Survey, by Schucht; Agrogeological Maps, by Timko 
and Gill; Agronomical Work in Bohemia, by Kopecky; Chemical 
Analyses of Soils, by Emszt and Sigmond; The Kords Floods, by Uj ; 
Soda-holding Soils, by Sigmond; Ampelogeological Maps,.by Dicenty ; 
Lime-holding Soils, by Treitz; Mineral Soils, by Atterberg; Unifica- 
tion of Methods of Chemical Soil Analyses, by Hilgard; and the Soils 
of Roumania, by Murgoci. 

DECADE V.—YOL. VII.—NO. III. 9 


139 Reviews—Brief Notices. 


3. Tae Waxariev Disrricr, New Zeatanp.—Professor James Park, 
in his Presidential Address to the Otago Institute, 1909, on the origin 
and history of the Wakatipu District, deduced from the facts observed 
by him in the course of his survey that probably in the Pleistocene 
Period the southern portion of the South Island of New Zealand had 
been covered by an ice-sheet, some 7500 feet in thickness. ‘That is 
to say, there has been an Ice Age in New Zealand similar to that in 
the Northern Hemisphere. 

4. Tue Temreratore oF THE Harte anp Harra-MovemMEentTs.—The 
Government of New Zealand has placed £200 at the disposal of the 
Philosophical Institute of Canterbury, New Zealand, to enable that 
body to investigate the temperature of the earth’s crust and other 
geophysical and geological phenomena rendered possible by the 
construction of the Arthur’s Pass Tunnel. It is further announced 
in the Proceedings of the New Zealand Institute that the Government 
are taking practical steps to erect bench-marks at suitable places along 
the coast. 

5. Tuer Tertiary Beps or Norru-Wesr Gurmany.—Dr. A. v. Koenen 
has brought together the latest information on the Tertiary of North- 
West Germany originally investigated by Beyrich fifty years ago. 
His pamphlet (2 Jahresber. Niederstchsischen geol. Ver. su Hannover, 
1909) sketches the Paleeocene, the Oligocene, and the Miocene, and 
gives a list of fossils from Volpriehausen, with annotations as to 
similar occurrences in the Scaldisian and the English Crag. 


6. Tue Geotocy or rHE WarersBere Trn-FIeLps, by H. Kynaston, 
E. ‘I’. Mellor, and U. P. Swinburne, forms No. 4 of the Geological 
Survey Memoirs of the Transvaal Mines Department, 1909. The ore 
occurs as Cassiterite. The geological structure of the country is 
comparatively simple. The central plateau is formed of the Upper 
Sandstones of the Waterberg system and the outer rim by the high 
ranges of granite and felsite which form the watershed between the 
Stark River and the Nyl and Magalakwin. Excellent coloured maps 
and sections accompany the paper. 

7. Tue Copper, Trin, anp Srrver Deposirs oF PrrKARANTA ON LAKE 
Lapoca form the subject of the Bulletin de la Commission Géologique 
de Finlande, No. 19( November, 1907). The report is written by Otto 
Triistedt, and occupies 334 pages. Many figures of rock-structure 
are given, and several plates are devoted to illustrating ‘‘ Kozoon- 
Serpentine Zones”. There is a colonred map, a table showing the 
output of the mines since 1814, and a list of all minerals recorded. 


8. Tur Miocene or AsrortA AND Coos Bay, Oregon (U.S. Geol. 
Surv., Prof. Paper 59, °1909).—Dr. W. H. Dall has reprinted 
twelve papers by previous authors on the same subject because of 
their inaccessibility to students living in the Pacific States. Happy 
students! And generous Government! The work itself is produced 
in Dr. Dall’s customary careful style, and is well illustrated by twenty- 
two plates of fossils, text-figures, and map. Many new forms are 
described, the validity of several genera is discussed in detail, and 
a further description of the fossil sea-lion (Pontolis magnus), by 
F. W. True, is appended, and illustrations of its skull are given. 


Reviews—Brief Notices. 131 


9. Tue Gortanpian or Fyrepat.—Professors J. E. Moberg and 
K. A. Gronwall have contributed to Meddelande frin Lunds Geo- 
logiska Faltklubb (ser. B, No. 3, 1909) a paper on the Gotlandian of 
Fyledal. ‘he beds are rich in the genus Bellerophon, and contain 
numerous ostracoda of a familiar type to those who work in similar 
English deposits. ‘Thus of nineteen forms described seven or eight are 
identical with those recorded from the Upper Silurian of England by 
Jones and others. 


10. New Zeratanp Geotocicat Survey.—From the geology of the 
Whangaroa subdivision, Hokianga division, by J. M. Bell and 
HK. de C. Clarke (Bull. N.Z. Geol. Surv., No. 8, 1909) we learn that 
the beds exposed in their area are pre-Cretaceous, late Mesozoic, 
Eocene, Miocene, and recent, with much intrusive and other igneous 
rock of doubtful age. Fossils are found of Cretaceous age, but they 
are imperfectly preserved and difficult to clean owing to the hardness 
of the matrix. They include Zrigonia, Desmoceras, Hamites, Ostrea, 
and Oxyrhina, and these are said to be insufficient, even with other 
fragmentary remains, to allow of correlation with the other New 
Zealand Mesozoic beds. ‘The igneous series are described in much 
detail, and numerous micro-sections of the rocks are given. The 
economic geology includes notes on cupriferous sulphides, mercury 
ores, precious metals, iron, manganese oxides, kauri-gum, oil, 
building and cement stones, mineral waters, and sulphur. A list 
of minerals met with, and a glossary of scientific and mining terms 
used in the report, are appended. 


11. A Fosstz Horss in Sourm Arrica.—Dr. R. Broom, among several 
Reptilian papers in the Annals of the South African Museum (vol. vii, 
pt. 11, April, 1909), calls attention to the evidence in favour of the 
existence of an extinct horse in South Africa. Three specimens have 
now been found, and the last ‘‘makes it pretty certain that a very 
large horse was a native of South Africa before European occupation ’’. 
In a slab of the coast-limestone cast ashore at Yzerplaatz is the 
greater part of the lower jaw of a large horse. This he now calls 
Equus capensis. he third premolar shows no trace of the rudimentary 
protostylid as compared with that of the modern horse. Teeth of 
a horse were described by Fraas from South Africa in 1908, and 
on May 11, 1909, Professor Ridgeway showed a portion of the fossil 
jaw of one of the Equide from Naivastra, German East Africa, to the 
Zoological Society of London. 


12. Fosstn VeRTEBRATES OF THE Karroo, Soura Arrica.—In the 
same number of the Annals of the South African Museum, Dr. Broom 
makes an attempt to determine the horizons of the fossil vertebrates 
of the Karroo. In drawing up the table he has ignored types. 
founded on vertebre or fragments of skeletons, as most of these 
are probably portions of animals already known from their skulls. 


18. Disrripurion or Iron Ores in Eeypr.—Dr. Fraser Hume 
discusses the Distribution of Iron Ores in Egypt, in Survey Department 
Paper No. 20 (Ministry of Finance, Egypt, 1909). Southern Sinai, the 
N.E. and 8.E. deserts, the oases, the ferruginous beds in the Nubian 


132 Reviews—Brief Notices. 


Sandstone, Sudan, Darfur, Kordofan, and Abyssinia are all referred to, 
and a map is given showing the distribution. The iron of Egypt does 
not appear to be of much commercial importance, but that of Darfur 
and Kordofan may possibly be worth attention in future. 


14. Creracrous or PonpoLtanp. — With regard to the age of the 
Cretaceous rocks of Pondoland and those of Port Durnford to beyond 
St. Lucia Bay, it has been shown by Mr. Henry Woods (Ann. South 
African Mus., iv (7), December, 1906) that they are the equivalent of 
the Campanian (Upper Senonian) of Europe, the Ariyalur Beds of 
Trichinopoli, and the Valudayur and Trigonoarea Beds of Pondicherri. 
Deposits of a similar age have been shown to occur in Madagascar. 
Griesbach supposed that five faunas could be recognized in successive 
zones of these African deposits, and correlated the uppermost with the 
Greensands and the White Chalk of England. Later on, Rogers and 
Schwarz showed that the fauna was more generally distributed 
vertically than Griesbach had supposed, and belonged to one deposit. 
Woods’ work confirms this, and proves that only one zone is represented. 


15. Tae Poospuatre Deposits or Sourn Carotina anD New Brons- 
wick. ByG.F. Marraew, LL.D., F.R.S.C. Bull. Nat. Hist. Society 
of New Brunswick, vol. vi, pt. 1, p. 121.—This is a brief account of 
a visit to the deposits on the rivers of South Carolina, from which 
so much calcium-phosphate has been obtained of late years, chiefly 
in the form of bones and teeth of extinct forms of vertebrates taken 
from layers under the river beds of those streams. The remains are 
of various ages, from the Eocene upwards, but have been rolled in 
the sea and redeposited in beds, which contain many recent shells 
and so are comparatively modern. These recent deposits are compared 
with the vastly more ancient Cambrian phosphates of New Brunswick, 
which have been accumulated under somewhat similar conditions. In 
these last-named beds the phosphatic nodules are mingled with 
Brachiopod shells and the detached portions of the heads and body- 
segments of trilobites. 


16. Geonoetcat ‘ltme.—In an article on ‘‘ The Accumulation of © 
Helium in Geological Time” (Proc. Roy. Soc., 1909, ser. A, 
vol. lxxxili, p. 96) the Hon. R. J. Strutt gives the results of 
investigations among iron-stones which contain heium. He remarks 
that the results on hematite from co, Antrim are especially note- 
worthy, as it would appear that the Eocene period must be put back 
thirty million years. 


17. Roya Scorrish Museum, Eptnpurcu.—A useful Jntroduction to 
Petrography and Guide to the Collection of Rocks in the museum 
has been prepared by Dr. 8. J. Shand (pp. 50, 1909), and is sold at 
the price of one penny. It deals with the Igneous, Sedimentary, and 
Metamorphic rocks, and contains introductory remarks on the nature 
and genesis of rocks, and on the general character of minerals. Moreover, 
it has a good index. 


Reports and Proceedings—Geological Society of London. 1338 


Ha PORTS AND PROC rE DENG S. 


I.—Groroetcat Socrrry or Lonpon. 


January 12, 1910.—Professor W. J. Sollas, LL.D., Se.D., F.RB.S., 
President, in the Chair. 


The following communications were read :-— 


1. ‘On the Igneous and Associated Sedimentary Rocks of the 
Glensaul District (County Galway).’’ By Charles Irving Gardiner, 
M.A., F.G.S., and Professor Sidney Hugh Reynolds, M.A., F.G.S.; 
with a Paleontological Appendix by Frederick Richard Cowper Reed, 
M.A., F.G.S. 


The general succession of the rocks of the Glensaul district is as 
follows, in descending order :— 


3. ? Bata Beps. Conglomerates and Sandstones. 
These beds have not been studied. 


2. SHANGORT AND TouRMAKEADY Bens. Thickness 
(8) Calcareous gritty tuff of no great coarseness, sometimes becoming in feet. 
so calcareous as to pass into fairly pure limestone, enclosing 
also bands and patches of limestone breccia, and, more rarely, 
bands of highly fossiliferous limestone which in some cases 
has been shattered by earth-movements. 
(7) Very coarse tuff or breccia, mainly composed of felsite fragments : 
associated with it are impersistent bands of fine tuff . : 750 
(6) Tuff, coarse and fine, with occasional patches of calcareous beds, 
and at one point graptolitic beds indicating the zone of 


Didymograptus hirundo . : : i : 150 
(5) Great felsite sill of Tonaglanna and Greenaun . : about 1100 
(4) Coarse grit . : : ‘ : 20 
(3) Gritty tuff. : vary ing in thickness from 520 to 620 
(2) Coarse tuff or breccia, mainly composed of of felsite fragments. 75 
(1) Fine banded tuff . c : 5 : é 5 5d 
1. Mount Parrry Beps. . 
(4) Coarse grits . : 150 
(3) Fine arits and tuffs associated with black chert, a eraptolitie beds, 


and a prominent band of coarse tuff or breccia about 30 feet 

thick. The sree indicate the zone of Didymograptius 

extensus . : . : : . (?) 150 
(2) Coarse grits . : é ae ey 110 
(1) Coarse conglomerates, about 600 feet seen. 


The graptolitic beds occurring in Band 3 of the Mount Partry 
Beds have yielded nineteen species, which have been determined by 
Miss G. L. Elles, D.Sc., who considers that they indicate the upper 
part of the zone of Didymograptus extensus. The commonest species 
met with are D. extensus, Hall, and D. bifidus, Hall, both species 
being represented by small mutations. Rounded bodies, which 
a comparison with the better preserved specimens from the 
Tourmakeady district shows to be almost certainly Radiolaria, were 
noted in sections of the cherts and shaly beds at several points. 

In a previous description of the rocks of the Tourmakeady district, 
the term Shangort Beds was applied to a series of grits and tuffs, and 
the term Tourmakeady Beds to an associated series of calcareous 
strata which generally take the form of limestone breccias. In the 


134 Reports and Proceedings—Geological Society of London. 


Glensaul district it is not possible to draw a sharp line of distinction 
between the two rock-types, some of the calcareous gritty tuffs 
passing into nearly pure limestone; but the authors retain the terms 
to indicate the close connexion between the two districts. 

The fossils from the Shangort and Tourmakeady Beds, which have 
been examined by Mr. F. R. Cowper Reed, show a close resemblance 
to those of the Tourmakeady district; but the finding of certain 
additional forms, especially ileus armadillo and Niobe sp., has 
impressed upon Mr. Reed the close connexion between this fauna 
and that of the Orthoceras Limestone of Sweden, and has convinced 
him that it is rather of Arenig than of Llandeilo age. The conclusion 
is in conformity with the field-evidence, for at one point beds of 
gritty shale, containing Radiolaria and Graptolites (indicating the 
zone of Didymograptus hirundo), occur associated with the tuff of the 
Shangort Beds. The relegation of the Shangort and Tourmakeady 
Beds of Glensaul to the Arenig would imply a similar age for those of 
the Tourmakeady district. 

The Glensaul district contrasts strongly with that of Tourmakeady 
as regards the character of the crystalline igneous rocks, which are all 
quartz-felsites, and the authors believe them to be entirely intrusive. 

Mr. F. R. C. Reed describes one species of Jl/enus, one of Niobe, 
one of Vileus, two of Bathyurus, three of Cheirurus, one of Phomera, 
one of Lnerinurus, one of Phacops, and a new species of Bathyurellus. 
He also describes three species of Orthis, one of Hyolithes, one of 
Rafinesquina, one of Camerella, and one of Porambonites, and his 
conclusions as to the evidence which is furnished by the fauna 
regarding the age of the beds are mentioned above. 


2. ‘*On the Gneisses and Altered Dacites of the Dandenong 
District (Victoria), and their Relations to the Dacites and to the 


Granodiorites of the Area.” By Professor Ernest Willington Skeats, 
Se. A.RC.S., B-G:S. 


The area described lies about 25 miles south-south-east of 
Melbourne. The earlier literature is discussed, and it is shown that 
the early geological surveyors regarded the dacites as Paleozoic 
‘traps’ passing gradually into the granodiorites. Professor J. W. 
Gregory first described the rocks as dacites, probably of Lower 
Tertiary age, resting upon the denuded surface of the granodiorites 
and of the adjoining Lower Paleozoic sediments. ‘The author 
describes the field-relations of the rocks, and shows that gneiss 
occurs between the dacite and the granodiorite in places. Elsewhere 
at the contact the dacite appears slightly altered. The contact with 
the plutonic rock is everywhere abrupt. No foliation or banding 
occurs in the granodiorites, but acid veins pass from the junction into 
the altered dacite and also cut across the foliations of the gneiss. 
The field evidence, therefore, shows that the dacites are older than 
the granodiorites, and also that the gneiss was formed before the 
intrusion of the acid veins. Chemical analyses of the rocks and of 
the coloured minerals of the dacites are recorded. 

The chemical evidence indicates that slight differentiation of 
a magma took place: the dacite was first erupted, and, following 


Reports and Proceedings—Geological Society of London. 135 


shortly on that, the granodiorite (of slightly more acid composition) 
was intruded into the dacite. The microscopic characters of the 
granodiorite, the dacite, the altered dacites, and the gneiss are 
described. In the altered dacites a slight banding or schistosity 
occurs near the contact, ilmenite is changed to secondary biotite by 
reaction with the felspar in the microgranular groundmass, biotite 
is corroded by the attack of the groundmass, and hypersthene is 
altered at its margin to secondary biotite and secondary quartz. 
Finally, minute granules of blue tourmaline occur in the contact 
rocks. All the changes enumerated above are attributed to contact- 
metamorphism caused by the intrusion of the granodiorite. 

In the gneiss, hypersthene is not found, ilmenite is rare, and 
the rock is completely foliated. It shows a granular groundmass 
similar to, but coarser in grain than, the groundmass of the dacite. 
Besides occurring at the contact, it has also been found in parallel 
zones intercalated in dacite near the contact. 

The author believes thet the gneiss is a peculiar modification of 
the dacite, but direct evidence as to its mode of origin is as yet 
incomplete. It may possibly be the result of extreme contact- 
metamorphism of a dacite of peculiar character, such as a tuff. It 
is possible that it was produced by differential movement in the 
dacite before complete consolidation, and certainly before the intrusion 
of the granodiorite. Since, however, dynamic effects are present in 
some sections, and are accompanied by changes found in the dacites 
altered by contact-metamorphism, the author is rather inclined to 
support the view that primarily the gneiss is due to differential 
movements in part of the dacite series, complicated by effects due to 
contact-metamorphism by the later intrusion of the granodiorite. 


3. ‘* Recent Improvements in Rock-Section Cutting Apparatus.” 
By H. J. Grayson, Demonstrator of Petrology and Assistant in the 
Geological Department, University of Melbourne. (Communicated by 
Professor KE. W. Skeats, D.Sc., A.R.C.S., F.G.S.) 

The apparatus described has been designed and constructed by 
the author, for use in the University of Melbourne. It comprises 
a slitting disk of mild steel and two bronze grinding laps, mounted 
on a very substantial wooden table. The disks and laps are each 
10 inches in diameter, and revolve at about 900 revolutions a minute. 
The disks and laps are connected with endless belts, which in turn 
are connected with wheels driven by a 1 horse-power electric motor. 
Special clamps are used to attach the rock-specimen and to cut the 
slice. A goniometric crystal-holder, permitting of slicing in any 
desired direction, is described, and can be fitted to one of the clamps. 
Clamps swinging radially across the grinding laps permit the parallel 
grinding of the slice to any required thinness. A polishing lap can 
be placed in the position of one of the grinding laps. The finishing 
of the slice is done by hand on a slate disk. In the second part of 
the paper the author describes in detail the method which he employs 
in making a rock-section, and refers to ’a number of improved methods 
or variations of the usual processes which he has in practice found 
advantageous. 


136 Reports and Proceedings—Greological Society of London. 


January 26, 1910.—Professor W. J. Sollas, LL.D., Se.D., F.R.S., 
President, in the Chair. 


The following communications were read :— 


1. ‘On a Skull of Megalosaurus from the Great Oolite of Minchin- 
hampton.” By Arthur Smith Woodward, LL.D., F.R.S., F.L.S., 
Sec. G.S. 

The specimen was discovered and prepared by Mr. F. Lewis 
Bradley, F.G.S., and shows for the first time the skull of Megalosaurus. 
It agrees closely with the Megalosaurian skulls of other genera 
already discovered in the Jurassic and Cretaceous of North America, 
and resembles Ceratosaurus in possessing a bony horn-core on the 
nose. As in the jaws of Jegalosaurus previously known, the pre- 
maxilla of the new specimen bears four teeth; but these teeth are 
so different from those of the typical Jf. bucklandi of the same horizon 
that they prove the Minchinhampton fossil to belong to a distinct 
species. 


2. ‘* Problems of Ore-Deposition in the Lead and Zine Veins of 
Great Britain.” By Alexander Moncrieff Finlayson, M.Se., F.G.S. 

Chemical analyses show traces of lead and zine in several of the 
rock-formations of Britain, but the ores of the veins are concluded 
to be derived, not from the country rock, but from deeper sources, 
probably in the first place by magmatic segregation. They were 
transported in the deeper zones by ‘juvenile’ waters, in which 
fluorme was an important constituent, while in the upper zones, 
especially in limestone districts, underground waters of meteoric 
origin have played a large part. The vein-solutions carried (1) alkaline 
sulphides, which held the sulphides of the metals in solution, and 
(2) alkaline and earthy carbonates. The presence of the latter is 
indicated by the alteration of the wall-rock, which shows a con- 
centration of potash, lime, and carbon dioxide, and a leaching of soda, 
magnesia, oxides of iron, and silica. In limestones, however, the 
chief effects of solution on wall-rock were concentration of silica and 
magnesia. 

The filling of fissures rather than direct replacement of rocks by 
ores has been the chief process, but the calcium of fluorspar has 
been very largely derived from the country rock. Further, much 
local metasomatism is seen, such as replacement of limestone by 
fluorspar, galena, blende, and quartz; and replacement of fluorspar 
by galena. 

The order of deposition determined by microscopic examination of 
polished specimens of ores has been: chalcopyrite, fluorspar, blende, 
gvalena. The galena carries its silver generally in molecular or 
isomorphous combination, except in the case of rich ores, when 
native silver and argentite appear sometimes as threads along the 
cleavage-planes. 

In the effect of the country rock on ore-deposition, the chief 
factors have been: (1) the physical character of the rock and the 
consequent nature of the fissure, (2) its porosity, and (3) its chemical 
composition. ‘The process of deposition involves interchange of con- 
stituents between rock and solutions, even with the least soluble rocks. 


Reports and Proceedings—Mineralogical Society. 137 


Ore-deposition- has persisted over a vertical range of 5000 to 
6000 feet, of which over one-half has been shorn off by denudation. 
The effects of secondary processes have been exerted to depths of over 
600 feet. The main points in the work are supported by field- 
observations, and by the results of microscopic and chemical research. 


3. ‘“*The Vertebrate Fauna found in the Cave-Earth at Dog Holes, 
Warton Crag (Lancashire).”” By John Wilfrid Jackson, F.G.S., 
Assistant Keeper in the Manchester Museum. 

The remains described in this communication were cbtained during 
the systematic investigation by the author of a cave on Warton Crag 
(West Lancashire) in 1909. 

The cave, known as Dog Holes, is situated on the western side of 
Warton Crag, and opens on a sloping ‘pavement’ of limestone. It 
owes its origin to the erosion of a series of master-joints in the 
Carboniferous Limestone. 

The present entrance to the cave is by a vertical drop from the 
general level of the ‘pavement’. This entrance is undoubtedly of 
secondary origin, and is due to the falling-in of the weakened roof of 
one of the passages. 

The specimens were derived from the cave-earth below the ates. 
soil in one of the chambers of the cave. They comprise a large series 
of small vertebrates, including Rodents, Insectivores, Amphibians, 
Birds, ete. Among the Rodents are some interesting forms, the chief of 
which are the Arctic and Norwegian Lemmings and the Northern Vole. 

A large series of non-marine Mollusca was found along with these 
remains, one species being of particular interest, namely Pyramidula 
ruderata, only known in this country by its fossil remains in Pleisto- 
cene deposits. 

The Pleistocene age of the remains is fully discussed, as well as 
their possible mode of origin through a former swallow-hole. 

In many respects the cave and its contents bear a striking 
resemblance to the famous Ightham Fissures. 


February 9, 1910.—Professor W. J. Sollas, LL.D., Sc.D., F.R.S., 
President, in the Chair. 


Dr. Douglas Mawson, B.Sc., B.E., Lecturer in Mineralogy in the 
University of Adelaide (South Australia), delivered a lecture entitled 
‘‘With Sir Ernest Shackleton in the Antarctic”, illustrated by 
lantern-slides. 

The President proposed and Sir Archibald Geikie seconded a vote 
of thanks to the Lecturer, which was adopted with acclamation and 
suitably acknowledged. 


TI.—MdInERALOGICAL Society. 


January 25.—Professor W. J. Lewis, F.R.S., President, in the Chair. 

Dr. 8. J. Shand: On a group of minerals formed by the combustion 
of pyritous shales in Midlothian. At the Emily Coal-pit, Arniston, as 
the result of the slow combustion of a heap of shaly refuse, whith 
became spontaneously ignited, presumably owing to the evolution of 


138 Reports and Proceedings—Mineralogical Society. 


heat caused by the atmospheric oxidation of pyrites, a number of 
uncommon mineral species have been formed, of which five have been 
recognized, viz. native sulphur, sal-ammoniac, tschermigite, mascag- 
nite, and a possibly new species, aluminium sulphate.—Professor W. J. 
Lewis: A Crystal-holder for measuring large specimens. For this 
purpose a clamp of convenient form and with various adjustments 
has been designed and made by Mr. Pye.—Mr. T. Crook: Some 
observations on Pleochroism. The phenomena of pleochroism dis- 
played by plates of coloured minerals when examined in ordinary light 
were treated in a general way for both parallel and convergent rays, 
and the factors upon which they depend were discussed.—Mr. L. J. 
Spencer: Notes on the Weight of the ‘Cullinan’ Diamond, and on 
the Value of the Carat-weight. Varying statements of the weight of 
the ‘Cullinan’ diamond, in its original, uncut form have been 
published, but from a comparison of the carat-weights against which 
it was weighed in 1905 it is concluded that the correct weight was 
621:2 grams, or 30252 English carats of about 205°304 milligrams (as 
defined by the Standards Department of the Board of Trade in 1889). 
Other values are, however, given for the English carat and for the 
carat in other countries, and the average value has decreased on the 
whole in course of time. The carat-weight had its origin in the use 
as weights of seeds of Ceratonia siliqua, which weigh approximately 
a carat. The existing confusion would be obviated by the general 
adoption of the metric carat of 200 milligrams (one-fifth of a gram) 
recently recommended by the International Committee of Weights 
and Measures (JVature, 1908, vol. 1xxii, p. 611).—Dr. G. T. Prior: 
On a Basalt from Rathjordan, Co. Limerick. Specimens of basalt 
from Rathjordan in the Allport Collection in the British Museum show 
in thin slices under the microscope round sections of isotropic material 
containing central and marginal inclusions, and thus resembling small 
leucites. The rock is very similar, mineralogically and chemically, to 
leucite-basalts from Bohemia, but contains only a small fractional 
percentage of potash. This fact, combined with observations of the 
refractive indices, leads to the conclusion that the isotropic material 
is mainly analcite and not leucite.—Dr. G. F. H. Smith and Dr. G. T. 
Prior: On a Fluo-arsenate from the Indian manganese deposits. 
A erystallographical and chemical examination made of the green 
arsenate from Kajlidongri, Jhabua State, mentioned in Mr. Fermor’s 
monograph on the manganese-ore deposits of India (Rec. Geol. Surv. 
India, 1908), led to the following results :—Composition (Mg F) Ca 
AsO, Specific gravity, 3°768. Hardness, 33. Colour, apple- to 
brownish - green. Monoclinic: a: b:c = 0°7485:1: 0°8453 : B= 
120° 50’. Forms present (010), (110), (111), (181), (811), (112), 
(152). Good cleavage parallel to (101), and partmgs parallel to 
(110), (102), (881). Twin plane (100). Refractive indices, 1°640, 
1660, 1°666. Acute bisectrix nearly perpendicular to (101), and 
axial plane at right angles to the plane of symmetry, but no horizontal 
dispersion was noticed; 2E= 105° approximately, with negative 
birefringence. The mineral is probably identical with tilasite, which 
was first described by Sjégren in 1905, from the manganese deposits 
of Langban, Sweden.—Mr. H. E. Clarke and Professor H. L. Bowman : 


Correspondence—J. B. Scrivenor. 139 


On the composition of a stone from the meteoric shower which fell at 
Dokachi, Bengal, on October 22, 1903. The small crusted: stone 
examined, weighing 17:8 grams, shows chondritic structure, and 
belongs to the class Ci of Tschermak. The chief constituent minerals 
are bronzite (37:9 per cent.), olivine (37:7 per cent.), nickel-iron 
(18:5 per cent.), troilite (4:1 per cent.).—Dr. G. F. H. Smith exhibited 
cut and rough specimens of synthetical sapphire, recently produced by 
Professor Verneuil, oxides of iron and titanium being the colouring 
agents. 


CORRESPONDENCE. 


THE USE OF THE TERM ‘LATERITE’. 


Srr,—I have read Mr. T. Crook’s letter in the November number 
of this journal with interest, but fail to see that he has made it easier 
for everyone to agree with him in his use of the term ‘laterite’. Ido 
not say that the engineers of the Malay Peninsula are correct in their 
use of the term. ‘They have not adhered to Buchanan’s definition, 
but have extended it to cover masses of ironstone, which, even had 
they occurred in decomposition products of crystalline rocks, I am 
quite ready to admit would not have been included in the term 
‘laterite’ by the originator. Similarly, I admit that in other countries 
the original definition has been abandoned, which is _ perhaps 
deplorable ; but the question that occurred to me immediately on 
reading Mr. Crook’s remarks was, what reason has he to consider 
himself in a better position as regards the original definition, which 
is conveniently given in his letter, than the rest ? 

The essential point in Buchanan’s definition is the fact that laterite 
‘sets’ when exposed to the atmosphere, and can be used as brick. 
Buchanan also says that it contains a very large quantity of iron in 
the form of red and yellow ochres. Now Mr. Crook says that 
Buchanan attached to the term ‘laterite’ a significance that is in - 
strict agreement with modern usage, by which we must understand 
Mr. Crook’s insistence on the importance of the free aluminium 
hydroxides. I can only take this to mean that in Mr. Crook’s opinion 
the ‘setting’ of laterite is essentially due to the dehydration of the 
aluminium hydroxides, and if Mr. Crook can prove this proposition 
I am prepared to accept his definition as a somewhat obscure 
paraphrase of Buchanan’s definition. At present I am unable to 
accept it as a paraphrase because, although a change from gibbsite 
to the hard but very brittle diaspore may to a small extent account 
for the hardening, it is but reasonable to suppose that in the case of 
Buchanan’s indurated clays containing ‘‘a very large quantity of 
iron”’, the redistribution and partial dehydration of the ferric hydrate 
are the factors that make laterite commercially valuable (vide Manual 
of the Geology of India, p. 379, and Sir Thomas H. Holland’s paper in 
the 1903 volume of the Gror. Mac., pp. 65, 66, and 69). 

It is clear that the original definition of laterite has been generally 
ignored, perhaps because it appealed to an economic rather than 
a scientific point of view. But with that idea of economic value 


140 Correspondence—Arthur W. Rogers. 


there was in the earlier writings always more than a suggestion of an 
abundance of iron, and those who apply the term now to distinctly 
ferruginous weathering products may be no nearer heresy than those 
who, following up the work of Max Bauer and Dr. Warth, insist on 
the presence of free aluminium hydroxides as the test of laterite. 
To me the term seems to be now of little value, and unless we can 
agree to apply it only to such materials as were described by 
Buchanan as possessing qualities that make them workable as 
a substitute for brick, I do not see why it should be retained. 
Mr. Crook tells me that I am not justified from a scientific standpoint 
in suggesting that highly aluminous laterite should be called bauxite. 
I follow Mr. Crook’s argument, but since the following phrases occur 
in the papers by Sir Thomas Holland and Dr. Warth & F. J. Warth 
published in the Gerotocicat Macazine for 1903 — ‘‘ laterite . 


agrees in essential characters with bauxite ’—‘‘ the essential chemical 
similarity between bauxite and laterite’’—‘‘laterites in situ which 
are bauxites ’’—‘‘ these bauxites in blocks and in powder” —“‘ laterite 


is bauxite in various degrees of purity” —I feel that I am justified 
in advocating simplicity of diction as opposed to the redefining of 
a term the utility of which to geologists is doubtful. 

‘The engineers, even if they have misapplied the term, are now the 
chief users of it, and weight of numbers will compensate such lack 
of scientific accuracy as exists in the eyes of the world at large. In 
local publications geologists placed like myself must make use of the 
term in order that local readers may know what is being discussed, 
and it was the objection in the Imperial Institute Bulletin to such 
a local use of the term that led me to write in the first instance, since 
I foresaw that the same might happen to me also. I believe that all 
geologists are agreed in aiming at simplicity of terminology. Can 
any geologist who has kept abreast of the literature use the term 
‘laterite’ now without feeling an obligation to explain what he means 
by it? And is it not simpler to say directly what we mean without 
using a term whose original significance we have discarded ? 

J. B. Scrrvenor. 

GxroLocicaL Department, Batu Gasan, 


FEDERATED Matay STATES. 
January 19, 1910. 


CAPE GEOLOGY. 

Srr,— Will you allow me to point out that your reviewer has made 

a mistake in his otherwise very kind remarks on the book on Cape 

Geology written by Mr. Du Toit and myself? He says that ‘‘ no 

references are given to any of the authorities quoted’’: a glance 

through the book will show that references to a considerable number 

of publications, in fact whenever such a course seemed desirable, are 

given in the foot-notes. In a book of this sort the omission of 

references would be a very serious fault, so the oversight on the part 
of the reviewer should be corrected. 


ArtHur W. Rocers. 
FRASERBURG, Carr Cotony. 
January 1, 1910. 


Obituary—Rev. G. F. Whidborne. 141 


JAW APPARATUS OF DISCOIDEA. 

Srr,—In the course of examining and arranging some specimens of 
foreign Lehinoidea, formerly in the Wright Collection and recently 
purchased for the British Museum, I have found an internal cast in 
flint of a Discoidea, which, from its size and general contour, seems 
referable to D. cylindrica (Jam.), although it isa remarkably depressed 
form. This cast exhibits clear impressions of the dental apparatus in 
a fragmentary condition, at least three of the teeth being represented 
among the other portions of the jaws. ‘The characters of the jaws in 
this specimen accord, so far as they are visible, with those of the 
individual in the Manchester Museum (Groz. Mac., 1909, pp. 148- 
52), which is almost equally depressed in outline. In view of the 
extreme rarity of the preservation of the dental apparatus in this 
genus, the existence of an example in the National Collection seems 
worth a published record. Unfortunately the precise locality and 
horizon are unknown. ‘The specimen is registered HK. 10166. 

Hurpert L. Hawkins. 


University CoLttecr, REeapinec. 
February 17, 1910. 


OS SPAS aa 


THE REV. GEORGE FERRIS WHIDBORNE, M.A., 
WEG Say anne 
Born 1846. Diep Frsruary 14, 1910. 

Ir is with deep regret we learn, from the Morning Post, February 17, 
of the death of our valued friend the Rev. G. F. Whidborne, M.A., 
at Hammerwood, East Grinstead, from an attack of pneumonia, in his 
sixty-fourth year. Mr. Whidborne formerly resided at Torquay, and 
in later years at Westbury-on-Trym, near Bristol. For the past 
twenty-five years he had devoted himself to figuring and describing 
‘“the Devonian fauna of the South of England”, in the annual 
volumes of the Paleontographical Society, the first part of which 
monograph appeared in vol. xli for 1888, and of which eleven fasciculi 
had been issued, the last part being published in 1907. Mr. Whidborne 
had served for many years on the Council of the Paleontographical 
Society, and has contributed papers to the Quarterly Journal of the 
Geological Society (in 1881 and 1883) and numerous papers to the 
Gxoroeicat Macazine (1889-1901). He was a most generous and 
kind-hearted man, an excellent paleontologist, and greatly esteemed 
by a very large circle of friends and fellow-workers. 


MISCHLILANHOUS. 


Z SS 
Mr. James Reeve, F.G.S., anp tHe Norwicu Casrire Museum. 
The admirable Museum originally known as the ‘“‘ Norfolk and 


Norwich Museum” was initiated in February, 1825, by a small body 
of private gentlemen, naturalists and antiquaries connected with the 


142 Miscellaneous. 


city and county, and started with the modest annual subscription 
of 5s. each member. It is to the honour of these gentlemen and 
their friends and successors that the Norfolk and Norwich Museum 
continued (supported by voluntary contributions) for nearly seventy 
years, and had, at the time of its transfer to the Corporation, some 
fifteen years ago, in addition to its books and pictures, its antiquities, 
its recent and fossil collections, a fine series of British and foreign 
birds, and the finest collection of raptorial birds in the world, formed 
and presented to the Norfolk and Norwich Museum by the late 
John Henry Gurney, Esq. 

In the Geological Collection are preserved the grand series of 
mammalian remains from the Forest Bed deposits of the Norfolk 
coast, formed by the late Mr. John Gunn, F.G.S., the Chalk and 
Crag collections of the late Mr. Samuel Woodward, besides those 
presented to the Museum in recent years by Mr. James Reeves, the 
present indefatigable curator. 

In 1886 the Norwich Town Council, presided over by their then 
Mayor, Mr. John Gurney, proposed the conversion of the ‘keep’ and 
prison buildings adjoining the Norwich Castle into a series of museum 
galleries, with a view to the transfer of the collections now belonging 
to the Norfolk and Norwich Museum. A committee was formed to 
raise the necessary funds, to which Mr. John Gurney contributed the 
handsome sum of £5000. 

More than £15,000 in addition were raised to complete the buildings, 
which were designed and carried out for the Corporation and the 
Museum Committee in 1887 and following years by Mr. E. Boardman, 
F.R.1.B.A., the city architect. Some years later Mr. James Reeve, 
¥.G.S., the Curator, who had devoted forty-six years of his life to the 
Norfolk and Norwich Museum, undertook and carried out the transfer 
of the entire collections from the old building in St. Andrew’s Street 
to the grand series of eight new spacious galleries and the ‘keep’ of 
the old feudal castle, and has since devoted sixteen years to the no less 
arduous task of arranging for exhibition the vast array of objects of 
art, pictures, antiquities, and relics; also of minerals, geological 
specimens, skeletons and skins of mammals, of birds and their eggs, 
of reptiles, of corals, insects, and mollusca, which now adorn these 
spacious and well-appointed galleries. 

But life is short and art is long—what wonder, then, that Mr. James 
Reeve, who has served the Norfolk and Norwich Museum, and sub- 
sequently the Corporation of Norwich, for an almost unexampled period 
of sixty-two years, should be wishful to retire from his arduous duties 
and obtain some needful repose! Even now his beloved Museum is 
his first consideration, and he writes to the Town Clerk: ‘‘I have 
naturally no desire to entirely relinquish a connexion which has lasted 
for more than half a century.” Whereupon the Castle Museum 
Committee (on January 5, 1910) resolved to place on record its high 
appreciation of the long and eminent services rendered by Mr. James 
Reeve, F.G.S., the Curator of the Castle Museum, etce., and to 
recommend that, in order to retain his valuable knowledge and 
experience, he be appointed Consulting Curator of the Museum, 
and that he be relieved from obligation to attend at the Castle during 


Miscellaneous. 143 


the usual hours that the Museum is open, but continue to give his 
advice and assistance to the Committee and its officers when required. 
It was further resolved that the salary of Mr. Frank Leney,’ Assistant 
Curator, be raised to £200 per annum from January 1, 1910, and that 
the consideration of the appointment of a Curator to fill the position 
to be vacated by Mr. James Reeve be deferred until after June 24, 1910. 

At a subsequent meeting on February 15 Dr. EH. E. Blyth, 
the newly-constituted? Right Honourable the Lord Mayor, with the 
Aldermen and Councillors, adopted the report of the Museum Com- 
mittee, and passed a cordial and well-deserved eulogium on Mr. James 
Reeve for his long and valuable services to the City of Norwich and 
its Museum. The Lord Mayor added that it was mainly due to 
Mr. Reeve that the Castle Museum contained more gems and less rubbish 
than any other of the Municipal Galleries in England. We heartily 
rejoice at the recognition given by the Corporation of Norwich to 
Mr. James Reeve for his valuable services, and trust that his life 
may long be spared to enjoy his comparative leisure and the well- 
earned appreciation of his fellow-citizens in Norwich. 


In Memory or Dr. Survon, or Lresmanacow, LanaRrKsHIRE. 


So long ago as 1855, at the Meeting of the British Association, 
Mr. Robert Slimon exhibited in Glasgow a remarkable series of fossils 
from Lesmahagow. Among these was a series of Crustacean remains, 
with curious scale-like markings, exposed upon the surface of dark- 
coloured schist or flags, to which Mr. David Page called Sir Roderick 
Murchison’s attention. Murchison at once recognized them as the 
remains of Pterygotus, and from the nature of the matrix concluded 
they belonged to the uppermost Silurian zone. At the close of the 
meeting, accompanied by Sir Andrew Ramsay and Dr. Slimon, 
Murchison visited the district, and, as the result of that visit, a very 
important addition was made to Scottish geology. Shortly afterwards 
Murchison read a paper to the Geological Society of London,* in which 
he stated that the dark fossiliferous shales exposed in the Logan Water 
pass conformably upwards into the Old Red Sandstone of that district. 
His paper was illustrated by a horizontal section showing the relation- 
ship that existed between the Upper Silurian strata of that region 
and the Old Red Sandstone. In his paper he also pointed out that 
Dr. Slimon’s collection contained sculptured plates of Crustaceans 
exactly similar to those which had already been referred to Pterygotus. 
Associated with these he had found specimens of Lingula cornea and 
Trochus helicites shells, which were characteristic of the Upper Silurian 
rocks of Wales. Such, then, is a brief account of this remarkable 
discovery in Scottish geology made by Dr. Slimon sixty years ago. 

The earliest Crustacean fossils, collected so zealously by Mr. Shimon, 


1 Formerly of the British Museum (Natural History), Cromwell Road, S.W. 

2 By command of His Majesty the King, February 2, 1910, that ‘‘the Chief 
Magistrate of the capital of the ‘ King’s county’ (Nortolk) should be raised to the 
rank of Lord Mayor”’ (Hastern Daily Press, February 16, 1910). 

5 See Q.J.G.S., 1856, vol. xii, pp. 15-19. 


144 Miscellaneous. 


were described by the late J. W. Salter! and in a monograph by 
Professor Huxley & J. W. Salter*; the specimens figured are preserved 
in the Museum of Geology, Jermyn Street. The British Museum 
next received specimens from Mr. Slimon, and Dr. Henry Woodward 
entered upon their description ;* a task which occupied him during 
intervals for more than fifteen years. Subsequently, in conjunction 
with Professor T. Rupert Jones, F.R.S., Dr. Henry Woodward 
prepared a monograph on the genus Ceratiocaris and other forms of 
Phyllocarida, many of which had been discovered by Mr. Slimon.* 

Dr. Slimon, to whose energy and ability as a field-geologist and 
naturalist we owe so much, died at Lesmahagow, October 12, 1882, 
in his eightieth year. 

In October last Dr. Slimon’s sons and daughter presented the whole 
of their father’s private collection, which he had added to up to his 
death, and which numbered over 5000 specimens, to the Kelvingrove 
Museum in Glasgow, where it will serve as a lasting memorial of 
Mr. Slimon’s: lifework. It may be interesting to learn that the 
shales containing these most coveted fossil-remains present their 
fissile edges vertically to the geologist, and are only to be met with in 
the beds and banks of the Nethan and Logan Waters and their 
tributary rivers. Here, standing knee-deep in clear cold water, 
Mr. Slimon and his sous spent many long days extracting their 
treasured fossils from their watery home in the river’s rocky bed. 

The story of Mr. Slimon’s great discovery is interesting. He was 
bound for Logan Water House, situated almost at the source of the 
Logan Water, to perform a very common though urgent medical duty, 
when his eye was suddenly arrested by a dark object in the rocks 
beneath the waters of the stream. Proceeding to obtain possession of 
it, he became entirely oblivious to the existence of such a thing as 
a patient, and it was not till something like ten hours had elapsed 
that he was suddenly recalled to the mission upon which he was bent, 
which was accomplished on the following morning. From the time 
when he first discovered the fossils up till his death, a period of over fifty 
years, Dr. Slimon was continually accumulating the vast collection, 
the great bulk of which has now found its final resting-place in 
Kelvingrove Museum.® But many fine and beautiful examples 
(mostly figured types) are fortunately to be seen in the British 
Museum of Natural History, Cromwell Road, and in the Museum 
of Practical Geology, Jermyn Street, London; also in the Edinburgh 
Museum, where they have been described and figured by Professor 
Dr. Malcolm Laurie, F.R.S.E., of St. Mungo’s College, Glasgow. 


1 Cf. Q.J.G.S., 1859, vol. xv, pp. 229-386, pl. x. 

2 T. H. Huxley & J. W. Salter, Mon. I, Mem. Geol. Survey, 1859, Svo, pp. 105, 
with 16 folio plates. 

3 See Intellectual Observer, 1863, vol. iv, p. 229, and pl.i; Guox. Maa., 1864, 
Vol. I, p..107, Pl. V; 1865, pp. 196 and 239, Pl. X; Brit. Assoc. Reports 
(Sect. C), 1865, Q.J.G.S., vol. xxi, p. 482, pls. xiii and xiv; Mon. Pal. Soc., 
Merostomata, 1865-78, pp. 1-263, pls. 1-xxxvi. 

4 See Mon. Pal. Soc., Paleozoic Phyllopoda, 1887-99, pp. 211, pls. i-xxxi. 

5 Under the care of that indefatigable Scotch geologist and naturalist, Peter 
Macnair, F.R.S.E., F.G.S., the Curator of the Natural History Collections. 


Price 2s. net. 


Decade V.—Vol. VII—No. IV. 


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I. OniGInan ARTICLES. Page | II. Reviews. Page 
| 

| Notes on New Chalk Polyzoa, etc. The Face of the Earth (Das Antiitz 
| By R. M. Bryponz, F.G.S. der Erde). By Eduard Suess. 
: PORN) se ke SRS AG Translated by H. B. ©. Sollas, 
| A New Species of Fossil Cockroach, directed by W. J.. Sollas ... ... 178 
| from the South Wales Coal-field. Memoirs of the Geological Survey : 
| By Herzerr Botton, F.R.S.E., The Melton Mowbray District \.. 181 
| F.G.S. (Plate XV and one Text- Geikie’s Geological Map of Scotland 182 
| figure.) ... ... - 147 III. Reports anp Proceeprnes. 


Some New Species of Cirripede, from 
the Cretaceous Rocks. By THomas 


Geological Society of London— 


H. Wirners. (With fourteen je See, Hebraary ba 1 =. 

Text-figures.) ees ee eee ee LONE Bh Shier eine oe 2 
The Geology of the Dolgelley Gold- TV. CoRREsPonpENce. 

belt, North Wales. By Arruur Cape: Colonye<s p22 Sars ares 189 

R. AnpreEw, M.Sc., F.G.S. --- 159 | Dr. J. W. Evans, ‘ Laterite’ ... ... 189 


Coral Zones in the Carboniferous V. Oxrrvary. 
Limestone. ByR.G.CarrutHERs, 


. Hendericus M. Klaa = 
of the Scotch Geolcgical Survey ... 171 ; : PA ecanannneh iat 
Aragonite in the Middle Lias of B. MarGunn,, VAC Re Maemstitgat 
Leicestershire. By A.R.Horwoop VL./ MisteLLAnzovs. 4, 
(Leicester Museum) . .. «. 173 | The Darwinian Theory - O-7154 (y92 
i A wD R i yal 


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ORIGINAL ARTICLIEHS. 


—_—_—_—_ 


I.—Norets oN NEW OR IMPERFECTLY KNOWN CHatk Potyzoa. 
By R. M. Brypong, F.G.S. 
(PLATE XIV.) 
(Continued from the February Number, p. 77.) 


Y next four species are linked together by their avicularia, which 
in each ease have the side walls infolded over a long deep-set area. 


MemeBranipora SAGITTARIA, noy. Pl. XIV, Figs. 1-3. 


Zoarium free or encrusting, always unilaminate. 

Zoecia elliptical; length of area -42 to 52 mm., with -48 mm. a fair 
mean; breadth -8 to °35mm.; the earlier specimens have practically 
common walls, the later ones show a progressive tendency to separation 
of the zocecia and sometimes a tendency to develop a second margin 
which reduces the area -29 to -31 mm. in length and -15 to -2mm. 
in breadth. 

Owcia very abundant but rather fragile, in the earlier specimens 
long and narrow, in the later ones showing a progressive tendency to 
broaden and fall back from the area. 

Avicularia of two types. (a) Accessory: in the zone of Mf. cor- 
anguinum small oblong rings lying at the head of the zocecium and 
occurring very regularly in pairs on either side of, and lying against, 
and slightly overlapping the occium, but nearly always failing to 
occur when a vicarious avicularium adjoins. In the specimen from. the 
lower part of the Actinocamax quadratus zone, shown as Fig. 2, they 
are developing in two directions, in one becoming exsert and over- 
lapping their surroundings, in the other sinking into the gradually 
deepening furrows between the zocecia and becoming mere triangular 
indentations; the latter line of development alone persists in the 
specimen from the upper part of the Act. quadratus zone shown as 
Fig. 3. (6) Vicarious: oblong cells with a long narrow elliptical 
aperture; there is a strong transverse bow-shaped ridge at the head 
of the cell, immediately below which the bounding walls are very 
sharply bent inwards until they overhang the aperture and almost 
meet in the middle line; they curve slowly back again and disclose 
a fairly wide front wall at the foot of the cell; just below the point 
at which they cease to overhang the aperture a pair of stout denticles 
are developed from the margin of the aperture. 

DECADE V.—VOL. VII.—NO. Iv. 10 


146 R. M. Brydone—New Chalk Polysoa, ete. 


Found in the If. cor-anguinum zone at Gravesend, in the Act. guadratus 
zone in various parts of Hampshire, and in the Belemnitella mucronata 
zone in the Isle of Wight. 


MEMBRANIPORA DoLIum, noy. Pl. XIV, Figs. 4-6, 


Zoarium free or encrusting, always unilaminate. 

Zowcia large; length of area ‘35 to ‘51 mm., with ‘45 mm. as a fair 
meat ; breadth -28 to: 43 mm., with °36 mm. as a fair mean ; the giant 
form from the Cromer-Weybourne Chalk shown in Fig. 6 gives average 
length of area 65 to ‘7mm. and breadth ‘5 to ‘°55mm.; the broad 
margins are quite distinct ; the areas are more or less barrel-shaped, 
owing to the strong tendency at the head to a straight margin, and at 
the foot to a slight intrusion of the preceding ocecium. 

Oecia abundant, large, and globose. 

Avicularia of two types. (a) Accessory: a pair of rings very 
uniformly present set against the areal margin at the upper corners. 
(6) Vicarious: elliptical cells with a wide elliptical aperture surrounded 
by.a narrow front wall; at about one-third of the way down the cell 
the bounding walls are bent inwards until they slightly overhang the 
aperture ; they continue for another one-third of the cell to overhang 
the aperture in a slowly increasing degree, and are then cut back to 
the edge of the aperture at a right angle, and for the rest of the isueth 
of the cell coincide with the margin of the aperture. 

Found in the Act. guadratus zone at various points in Hanpehitee, 
and with B. mucronata at Bramford in Suffolk, and in the Cromer— 
Weybourne Chalk, but not yet at Trimingham. It agrees very closely 
with I. lyra, as fieured by Hagenow,' except that the latter has not 
vicarious avicularia according to cither figure or description, and it is 
not likely that Hagenow would have overlooked them if they did occur. 


MEMBRANIPORA ANGUIFORMIS, noy. Pl. XIV, Figs. 7 and 8: ~ : 


Zoarium unilaminate, always encrusting. 

Zoecia small, length ae area °27 to °32 mm., breadth ‘238 to °26 mm. A 
subcireular, with very distinct margins, and often separated by deep 
fissures. 

Owcia very abundant, but very fragile; the specimens shown by 
Fig. 7 are the only ones 1 have seen, and unfortunately three out of 
the four have become defective and the fourth cracked since that 
photograph was taken; they are very wide, but too short to reach the 
area, with straight free edges, their general shape being much that of 
a beehive; the traces they eave when broken away are very indistinct. 

Avicularia of two types. (a) Accessory: a pair of perforated 
tubercles very constant in occurrence, set. on the margins at the upper 
corners of the zocecia, and having nearly always in mature zoccia 
a.low semicircular extension. upwards, with a shallow pore at the 
change of level; they then combine with the zocecial margin to give 
a strong sug gestion of the upper half of a snake. (6) Vicarious: 
largish elliptical cells, with a long narrow aperture tapering slightly 
from head to foot, and constricted near the foot by two small paired 


1 Loe. cit., p. 98, pl. xi, fig. 2. 


Grout. Maa. 1910. Pratt XLV. 


R. M. Brydone photo. 


Chalk Polyzoa. 


H. Bolton—A New Species of Fossil Cockroach. 147 


denticles, and surrounded by a narrow front wall which is deep-set at 
the head of the cell, and rises steadily towards the foot ; in the centre 
of the cell the bounding walls are bent rather sharply inwards to the 
edge of the aperture and back again; these avicularia have a strong 
general resemblance to those of Jf. envigilata, but it will be observed 
that the denticles in I. angusformis and I. sagittaria, being processes 
from the margin of the aperture, are not analogous to the denticles of 
M. invigilata, which are processes from the bounding wall. 
Found only at Trimingham. 


Mempranipora Laner,' nov. Pl. XIV, Figs. 9 and 10. 

Zoarium unilaminate, always encrusting. 

Zoecia often large, but very variable; length of area ‘43 to °7 mm., 
with °65 mm. asa fair mean in good specimens ; breadth -32 to -5mm., 
with -45 mm. as a similar mean; boundaries clearly marked owing to 
differences of level between adjoining zocecia but not by any furrow. 

Owcia long and rather straight-sided, often projecting slightly 
over the area of the succeeding zocecium, and generally rising from 
a slight protrusion of the margin of the aperture ; in one zocecium in 
Fig. 9 the protrusion has been formed, but no ocecium has developed 
from it. 

Avicularia of one type (vicarious) only, rather low-lying, and 
forming the initial cells of new rows of zocecia; elliptical, with wide 
elliptical apertures surrounded by a fairly wide front wall at the head 
of the cell and by a narrower one at the foot, but overhung considerably 
in the middle by the very symmetrically inbent edges of the bounding 
walls, which present the outline of an hour-glass. 

Found abundantly at, Trimingham, occasionally in the Cromer— 
Weybourne Chalk, and once in the Act. guadratus Chalk of Hampshire.” 


EXPLANATION OF PLATE XIV. 
(All figures x 11 diam.) 


MUembranipora sagittaria, zone of M. cor-anguinum, Gravesend. 
Ditto, zone of Act. guadratus (lower part), Hants. 

Ditto, zone of Act. quadratus (upper part), Hants. 

M. dolium, zone of Act. guadratus (upper part), Hants. 

Ditto, zone of B. mucronata (?), Bramford, Suffolk. 

Ditto, Cromer-Weybourne Chalk. 

M. anguifor mis, Trimingham. 

Ditto, Trimingham (another specimen). 

M. Langi, exceptionally preserved, Trimingham. 

Ditto, in ordinary preservation, Trimingham. 


SD OAD OV Co bo 


a 


It. — On a New Spectres or Fosstn Cockroacu, -ArCHIMYLACRIS 
(ZrostatTtina) Woopw4kpi, From THE SourH Waters CoAL-FIELD. 
By Herzerr Botton, F.R.S.E., F.G.S., of the Bristol Museum of Natural History. 
(PLATE XV.) 

(V\HE Orthopteron wing which forms the subject of the present 

paper was obtained by Mr. David Davies from a dark-blue shale, 
about 10 feet in thickness, overlying the No. 2 Rhondda coal-seam in 


1 Dedicated to W. D. Lang, Esq., of the British Museum (Natural History). 
2 Erratum: p. 76, 1. 29, for construction read constriction. 


148 H. Bolton—A New Species of Fossil Cockroach. 


Clydach Vale (see Plate XV). The shale decreases to the east, dying 
out wholly 2 miles beyond the colliery, giving place to sandstone. Iam 
indebted to Mr. Davies for the opportunity of describing the specimen. 

The wing or tegmina lies upon a very small piece of black shale 
and shows the upper surface, which is gently convex along the middle, 
somewhat hollowed over the mediastinal area, and more strongly 
curved along the inner margin and over the anal area. The basal 
portions of all the veins, and the whole of the internomedian and anal 
veins are well elevated above the general surface, the rest lying, as do 
all the smaller branches, below the general level. The ‘ cross-veins’ 
of Scudder are remarkably well preserved over the whole wing surface, 
forming a multitudinous series of fine close-set parallel ridges, which 
give a ladder-like appearance to the areas lying between the veins. 
The general impression is that of a finely wrinkled integument, which 
it really is, for where the chief veins or their branches are sunken, the 
‘cross-veins’ pass clean across the vein without any break, or any 
visible connexion. This is especially noticeable in the mediastinal 
area, where the wrinkles can be traced over several of the tertiary 
branches of the vein in succession. All the wing anterior to the 
internomedian area, and with the exception already noted, 1.e. the 
base of the principal veins, is distinguished by the veins lying in 
shallow troughs, between which the wing-structure rises in a well- 
rounded surface. The internomedian and anal areas, on the other 
hand, form an inner and smaller division of the wing in which all 
the veins are in high relief, the wrinkled surface lying in flattened 
hollows between. 

The wing appears to be complete, but is encroached upon by the 
shale in two small places on the outer margin. Considering the wing 
as a whole, it may be described as stout and robust, much shorter for 
its width than is seen in most species of toblattina, and possessing 
a regularly convex anterior margin which passes insensibly into the 
outer border; the latter is almost semicircular in outline, whilst 
the inner border is so feebly concave as to at first appear perfectly 
straight. At the base of the wing the full course of the veins cannot 
be traced to their point of attachment. 

The mediastinal vein curves forward for two-thirds of its length, 
then backwards, but not so sharply as the margin of the wing, which 
it therefore continues to approach. Finally it bends outward and runs 
to the margin, reaching the latter a little beyond the middle. The 
whole course of the vein is somewhat sigmoidal, and not so straight, for 
example, as shown by Scudder in Z. venusta.? 

Sixteen secondary veins at least spring from the mediastinal, four of 
which do not bifurcate. In the basal third of the area the presence 
of secondary veins cannot be distinguished. All the secondary veins 
approach the margin obliquely, with the exception of the last, which 
curves forward to meet it. The scapular vein forks at about the first 
quarter of its length into two unequal secondary branches. The 
anterior branch, which is the smallest, rans somewhat parallel to the 


1 Scudder, ‘‘ Paleeozoic Cockroaches”’: Boston Soc. Nat. Hist., vol. iii, pl. vi, 
fig. 12. 


H. Bolton—A New Species of Fossil Cockroach. 149 


mediastinal vein, breaking up into fine tertiary veins, the first two of 
which again fork before reaching the margin. The median branch of 
the scapular divides into two equal tertiaries, the anterior forking 
twice before reaching the margin, and the hinder forking but once. 

The scapular area occupies a little less than the outer half of the 
anterior margin of the wing, and almost exactly half of the external 
margin. Notwithstanding a general correspondence of the scapular 
vein with that of #. venusta, it occupies more of the anterior margin, 
owing to the forward curve of the anterior secondary vein, a curve 
which is continued in the tertiary branches, causing them to reach the 
margin a little beyond the middle of the latter’s length. 


Anal veins 
Moediasttnal----}---- \\ 
Scapulap-}---; Anal furrow 
Externomedian~, \| Internomedian 


~~ 
x 3 
% 
& y 
2 
& is 
: 
& y 
; 3 
5 
3 8 
Q m 
~ 
.~ 
3 
3 


Outline figure of one of the tegmina of Ztoblattina mazona, from the Carboniferous 
beds of Illinois, with the nomenclature of the veins as used by Heer and followed 
by Scudder (see Bulletin U.S. Geological Survey, No. 124, 1895, ‘‘ Revision of 
the American Fossil Cockroaches, etc.,’’ p. 37, fig. 3). 


The externomedian vein follows a sub-parallel course to the hinder 
secondary of the scapular, and remains undivided until it reaches the 
secondary forking of the latter. In this respect, the specimen again 
differs from ZL. venusta, where the forking occurs at a lower level. 
An examination of Scudder’s drawing shows that the primary forking 
of the externomedian, and the secondary forking of the scapular, lie 
in an oblique line directed forwards and outwards, whilst in the 
present case the same points of division lie upon a straight line 
bisecting the wing. The externomedian in the present specimen 
shows no internomedian branch in its lower third such as is indicated 
by Scudder. Beyond the first fork the hinder branch divides twice, 
so that the externomedian divides up into four branches, all of which 
reach the margin without further subdivision. The externomedian 
area is very small, and subtends not more than one-third of the tip of 
the wing. The internomedian vein follows a course parallel to the main 
axis of the externomedian, and after curving backwards a little in the 
first quarter of its length, passes straight outward to the hinder edge 
of the wing tip, giving off to the inner margin nine simple straight 
and unforked branches. The marginal area occupied by this vein and 


150 HH. Bolton—A New Species of Fossil Cockroach. 


its branches includes the outer two-thirds of the inner margin, and 
a small portion of the outer or tip of the wing. A slight fold 
separates the anal veins from the lowest branch of the internomedian, 
and divides off a small triangular lobe from the rest of the wing. 
The anal lobe thus formed is crossed by four anal veins which run 
parallel, and in the case of the basal two at least fork before they 
reach the margin. In the almost straight course which the anal veins 
pursue to the inner margin they are in marked contrast to those of 
EL. venusta, whilst the anal area is also much less. 

Specific Relationships.—A comparison with the tabulated specific 
characters of all known European and American Ztoblattina, shows 
that this specimen presents well-marked differences. From . mani- 
toides ' it differs in the greater length of the mediastinal vein and its 
area, in the presence of four anal veins, and in the more simple 
unbranched character of the internomedian. The differences of 
shape, size, and character of the veins when contrasted with 
£. Johnsoni, Woodward (Guot. Mae., New Ser., 1887, Dec. III, 
Vol. IV, p. 58, Pl. II, Figs. 1a—6), are still greater. It will be 
sufficient to note that the mediastinal area is almost one-half less 
than in £. Johnson’. FE. Deanensis, Scd., shows a somewhat superficial 
resemblance, but in that species the wing is narrower, and possesses 
a somewhat pointed tip in place of the well-rounded margin shown in 
our specimen. The general courses of the mediastinal and scapular 
veins are much less curved; and the latter is regularly forked, which 
is not the case in this species. The specimen, on the other hand, 
agrees perfectly with Scudder’s description of £. propria (op. cit.) in 
that the tegmina is less than twice as long as broad; the mediastinal 
area reaching nearly to the middle of the distal half of the tegmina; 
and the externomedian first forking beyond the middle of the wing. 

An examination, however, of Kliver’s figure (Paleontographica, 
xxix, pl. v, taf. xxxv, fig. 3) shows that the mediastinal area is 
longer in #. propria, and that the veins in the latter pursue a much 
straighter course. The chief difference, however, lies in the character 
of the scapular vein. In £. propria the scapular vein gives off the 
externomedian, about 8mm., above the base of the wing, whilst it is 
questionable whether these were ever united at all in the Welsh 
specimen. Unfortunately, the specimen is not sufficiently well 
preserved at the base to establish the point. Even had the two 
veins a common origin, the externomedian vein must have been given 
off from the scapular at the very base of the wing. It is, however, 
in the shorter mediastinal area, the forward curving of all the 
ultimate branches of the mediastinal and scapular veins, the more 
regular convexity of the anterior border, and the evident concave 
posterior or inner margin, that the chief differences consist, and 
constitute what may be regarded as specific identity. Further, 
Kliver’s drawing shows no trace of ‘cross-veins’, which are so 
strongly marked upon the tegmina of our specimen, the interstices 
between the veins being filled instead with a close reticulation. 

Handlirsch (‘‘ Revision of American Paleozoic Insects,” Proc. 


1 Scuddér, Mem. Boston Soc. Nat. Hist. Soc., 1879, vol. iii, pl. 1, No. 3. 


tnon. Mac. 1910. PLATE XV. 


Pe) 


Photo by J. W. Tutcher. 


Archimylacris (Etoblattina) Woodwardi, Bolton. South Wales Coal-field, 


DT. H. Withers—New Chalk Cirripedes. 151 


United States Nat. Mus., 1906, vol. xxix, pp. 661-820), who received 
the entire collection of Scudder’s types in 1902, has since produced 
a monograph materially altering the relationships of many of the 
forms previously described, established a number of new genera, and 
revised previously existing ones. In the light of Handlirsch’s con- 
clusions, our specimen falls into the genus Archimylacris of Scudder, 
the type of which is Archimylacris acadica, Scd., with Archimylacris 
(Htoblattina) venusta as a nearly related species. I have much pleasure 
in naming the species A. Woodwardi, after Dr. Henry Woodward, 
to whom more than any other in this country paleontologists are 
indebted for their present knowledge of Paleozoic insects. 


EXPLANATION OF PLATE XY. 


Fie. la. Wing or tegmina of <Archimylacris (Etoblattina) Woodwardi, Bolton. 
Nat. size; length 18mm., width 10mm. Photographed from the 
original specimen by Mr. J. W. Tutcher. 

», 16. The same wing enlarged rather more than twice natural size. 


The specimen was obtained by Mr. David Davies from a dark-blue shale (about 
10 feet in thickness) overlying the No. 2 Rhondda Coal-seam in Clydach Vale. 


T1I].—Some New Specirs oF THE CIRRIPEDE GENUS SCALPELLUM 
FROM British Cretaceous Rocks. 


By Tuomas H. WrrHers. 


INCE the publication of Charles Darwin’s memorable monograph 
on the Fossil Lepadide (Paleontographical Society, 1851) little 
has been written on the British Cretaceous Cirripedes. Among the 
thirteen species of Scalpellum which Darwin figured and described, 
ten are British, and, so far as I am aware, only one, Scalpellum 
attenuatum,’ has since been added to their number. Several species 
have, however, subsequently been described from Foreign Cretaceous 
Rocks. 

During an examination of the collection of English Cretaceous 
Cirripedes in the British Museum (Natural History), I noticed several 
specimens which cannot be referred to any described species. They 
all belong to the genus Scalpellum, and by permission of the Keeper of 
the Geological Department, descriptions and figures are now given 
of them. 

The work of comparison has been rendered easier by the identification, 
in the course of it, of several of the type-specimens figured and 
described by Darwin (1851). Some of these are referred to in the 
following pages. 

Although I have followed Darwin and later authors in regarding 
certain characters as of specific value, I do not ignore the possibility that 
the forms here described as distinct species may eventually prove 
to be only stages or mutations in their development, and may perhaps 
connect forms already known. But not until all the existing material 
shall have been discriminated and recorded, and additional specimens 
are available from several horizons, will it be possible to apply 


1H. Woodward, ‘‘ Cirripedes from the Trimmingham Chalk and other localities 
in Norfolk’’: Gzor. Mac., 1906, Dec. V, Vol. III, p. 352, Text-fig. 37. 


152 T. H. Withers—New Chalk Cirripedes. 


Darwin's theory of evolution to the fossils which his study has 
rendered. classical. . | 


1. ScALPELLUM ACCUMULATUM, sp. nov. Figs. 1-4. 


_ Diagnosis.—Carina narrow, moderately tapering, considerably bowed 
inwards, with inner margin much curved, not divided into parietes and 
intraparietes; apex pointed; basal margin rounded. Tectum very 
gently convex, almost flat, with obscure central ridge, marked off from 
the parietes by a well-developed ridge. Parietes narrow, less than 
half the width of the tectum, inflected, gently concave. Ornament: 
fine obtusely-angled V-shaped growth-lines continued over the parietes ; 
near the basal margin are five ridges, similar in shape to the growth- 
lines, but irregularly spaced, strongly marked, and sharper on the 
parietes. 


Fic. 1. Scalpellum accumulatum, T. H. Withers, sp. nov. External view of carina, 
x 2 nat. size. Aptian, upper part of Lower Greensand (Folkestone 
Beds) : Folkestone, Kent. (B.M., I. 12,928.) 

Id. Side view, x 2 nat. size. 

Id. ‘Transverse section at one-third from apex, x 2 nat. size. 

. Id. Transverse section at one-third from base, x 2 nat. size. 


Holotype.—A carina (B.M., I. 12,928) collected by Mr. F. H. Butler. 
The specimen, of which the basal margin is slightly broken, is in 
a matrix of very coarse-grained greensand. Extreme length 17mm., 
breadth 4mm. 

Horizon and Locality.—Aptian, upper part of Lower Greensand 
(Folkestone Beds): Folkestone, Kent. 

Comparison with other Species.—Scalpellum simplex, Darwin (1851, 
p- 39, pl. i, fig. 9), of which only a single carina is known, is the only 
species of the genus previously known from the Lower Greensand 
of the British Isles. It differs from S. accumulatum in having the 
parietes more inflected, set inwards, and not extending to the basal 
margin. Also in the much more convex transverse section of the 
carina, and the smooth surface. S. accumulatum may also be compared 
with S. arcuatum, Darwin (1851, p. 40, pl. i, fig. 7), from the Gault, 
and S. trilineatum, Darwin (1851, p. 38, pl. i, fig. 5), from the Grey 
Chalk, with both of which it agrees in the absence of a division 
into parietes and intraparietes. From S. arcuatum it is readily 
distinguished by the absence of the longitudinal ridges, and from 
S. trilineatum by the absence of the well-marked rounded central 
ridge, and the presence of the prominent V-shaped ridges near the 


He Oe bo 


T. H. Withers—New Chalk Cirripedes. 153 


basal margin. The type of S. trilineatum (B.M., 38,461) was collected 
by W. Griffiths in the Grey Chalk (Cenomanian) of Dover. 
S. accumulatum also disagrees with S. angustatum (H. B. Geinitz) 
from the Planerkalk of Strehlen, Saxony, and S. guadricarinatum 
(A. Reuss)* from the Planerkalk of Bohemia, in the absence of 
intraparietes. S. quadricarinatum further differs in the abrupt 
truncation of its basal margin. 


2. ScALPELLUM coMPTUM, sp. noy. Fig. 5. 


Diagnosis. —General outline of tergum almost rhomboidal, ornamented 
with fine raised longitudinal ridges, some being finer than others. 
Apex pointed, but not sharply; basal angle probably rounded. Carinal 
margin forming an obtuse angle. Scutal margin sinuous, longer than 
the occludent margin, which is almost straight. A delicate furrow 
divides the valve unequally from the apex to the basal margin, the 
oceludent portion being in its widest part about three times the width 
of the carinal portion. Carinal portion of valve ornamented with 
several fine raised longitudinal ridges, one of which is situated 
immediately at the side of the furrow, making the furrow more con- 
spicuous. Occludent portion almost equally divided by a prominent 
raised ridge, somewhat coarser than the others, extending from the 


Fic. 5. Scalpellum comptum, T. H. Withers, sp. nov. External view of left 
tergum, x 4 nat. size. Aptian, Lower Greensand: Sevenoaks, Kent. 
(B.M., I. 13,403.) . 


apex to the scutal margin. Between this ridge and the furrow the 
valve is ornamented with longitudinal ridges, which are finer and 
less elevated than those on the rest of the valve. The occludent 
margin has a raised border ornamented with several longitudinal 
ridges, similar in size to those on the carinal portion of the valve, 
followed by a wide groove, almost smooth, extending from the apex 
to the scutal margin, which is immediately bounded by the single 
longitudinal ridge. The growth-lines are more conspicuous on the 
occludent portion, where they are sinuous. This sinuosity is more 
marked between the single longitudinal ridge and the occludent 
margin. 


1 Die Versteinerungen von Kieslingswalda, ete., Dresden and Leipzig, 1843, p. 7, 
pl. iv, fig. 10. 

> Die Versteinerungen der Bohmischen Kreideformation, Stuttgart, 1846, p. 105, 
pl. xlu, fig. 18. 


154 T. H. Withers—New Chalk Cirripedes. 


Holotype.—Left tergum (B.M., I. 13,403), Caleb Evans Collection. 
Length of valve about 8mm., breadth 4mm., length of occludent 
margin about 5 mm., length of scutal margin 4mm. 

Horizon and Locality.—Aptian, Lower Greensand: Sevenoaks, Kent. 

Another specimen, a right tergum (B.M., 13,404) from the same 
collection, locality, and horizon, undoubtedly belongs to this species. 

Both terga have their basal angles broken, but judging from the 
adjoining outline of the margins there is little doubt that they were 
rounded. The left tergum is taken as the holotype, as it is the most 
perfect. 

Comparison with other Species.—Under the name Pollicipes radiatus, 
J. de C. Sowerby (1836),1 figured two valves of a Cirripede, which 
appear to be of different species. The only description given is: 
‘‘ Valves wedge-shaped, flat, marked with sharp, elevated rays, 
diverging from their apices.” Darwin in his monograph (1851, p. 40) 
says of Scalpellum arcuatum: ‘‘This species appears to come nearest 
to Pollicipes radiatus of J. de C. Sowerby . . . but besides that that 
species comes from the Lower Greensand, the lower angle is much 
more pointed; the upper figure of the two appears to be something 
wholly different.” Further, Darwin (1851, p. 80) says: ‘‘The 
P. radiatus of the same author (J. de C. Sowerby) of the Lower 
Greensand (pl. xi, fig. 6) is unknown to me; the tergum figured is 
like that of S. arcuatum; the upper figure, if a scutum, is very 
remarkable.’’ As these two valves figured by J. de C. Sowerby 
apparently belong to different species, it seems advisable to fix the 
holotype, and I therefore select the upper figure as the type of 
Pollicipes radiatus. It may be that Sowerby’s lower figure repre- 
sents a valve of S. comptum, but since the specimen cannot now be 
traced, and the figure and description are quite insufficient for exact 
determination, it is advisable to establish a new species for the 
specimens mentioned above, and to place in it provisionally the 
original of Sowerby’s lower figure. 

S. comptum may be compared with the Albian S. arcuatum, Darwin 
(1851, p. 40, pl. i, fig. 7), from the Gault, and S. fossula, Darwin 
(1851, p. 24, pl. i, fig. 4), from the Senonian (Bel. mueronata-zone) 
of Norwich. Both agree with it in having a delicate furrow 
extending from the apex to the basal angle; S. fossula further agrees 
in having a slight longitudinal ridge dividing the occludent portion 
into two parts. This ridge, however, is not raised as in S. comptum. 
In S. fossula the surface is not ornamented with raised longitudinal 
ridges, but is almost smooth; the carinal portion of the valve is 
proportionately much narrower, the apex and the basal angle are 
much more pointed, and the scutal margin is not sinuous. S. arcuatum 
differs by the absence of the raised longitudinal ridge extending from 
the apex to the scutal margin, and by the lines of erowth being much 
more sinuous on the occludent portion. The general outline is more 


1 Descriptive notes respecting the shells figured in pls. xi to xxiii, Appendix A, 
to W. H. Fitton, ‘‘ Observations on some of the Strata between the Chalk and the 
Oxford Oolite in the South-East of England’: Trans, Geol. Soc., ser. 1, vol. iv, 
pl. xi, fig. 6. 


T. H. Withers—New Chalk Cirripedes. 155 


oval, and the raised longitudinal ridges which occur nearly regularly 
over the entire valve give it a far different appearance. 


3. ScaLPELLUM cyPHUM, sp. nov. Figs. 6-9. 


Diagnosis.—Carina narrow, moderately bowed inwards, with inner 
margin slightly curved, widening gradually from the apex, which is 
sharply pointed, divided into parietes and intraparietes; basal margin 
angular (about 75°). Tectum strongly arched transversely. Parietes 
narrow, steeply inclined from the tectum, slightly concave, about half the 
width of the tectum, widening gradually to the basal margin. Tectum 
and parietes ornamented with a number of coarse, rounded, longi- 
tudinal ridges, readily seen with the naked eye. One stronger ridge 
runs down the middle of the tectum, and one on each side divides the 
tectum from the parietes. The interspaces between the ridges are 
about three times the width of the ridges. Intraparietes separated 
from the parietes by a strong rounded ridge, measuring in their 
widest part slightly more than the rest of the valve at that part, 
widening rapidly from the apex and then narrowing rapidly until 
a little more than half-way down the valve, when they merge. into 
the sides of the parietes, at a short distance from their basal margins. 
Surface of tectum and parietes covered with well-marked V-shaped 
growth-lines. 


Fic. 6. Scalpellum cyphum, T. H. Withers, sp. nov. External view of carina, 
x 2 nat. size. Cenomanian, Grey Chalk: near Dover, Kent. (B.M., 
I. 13,405.) 

7. Id. Side view, x 2 nat. size. 

», 8. Id. Transverse section at one-third from apex, x 2 nat. size. 

,, 9. Id. ‘Transverse section at one-third from base, x 2 nat. size. 


Holotype.—A carina (B.M., I. 18,405), J. Starkie Gardner Collection. 
Extreme length about 22mm., greatest breadth 5mm. The basal 
angle of the specimen is broken, but judging from one side of the 
margin it was probably angular. 

Horizon and Locality.—Cenomanian, Grey Chalk: near Dover. 

There is in the British Museum (Natural History), (B.M., I. 13,406), 
from the same horizon, locality, and collection, a smaller carina, which 
probably belongs to this species. It agrees in most of its characters 
with the preceding description, but the central longitudinal ridge is 


156 T. H. Withers—New Chalk Cirripedes. 


more pronounced, and some of the remaining ridges on the tectum and 
parietes are more irregularly placed and a little less coarse. 

Comparison with other Species.—The Albian Scalpellum areuatum, 
Darwin (1851, p. 40, pl. i, fig. 7), a common Gault species, also has 
longitudinal ridges, which, however, are finer and confined to the 
tectum. SS. cyphum is at once distinguished from that species by its 
greater transverse convexity and by the presence of intraparietes. It 
agrees in some of its characters with S. aduncatum, sp. nov. (see 
infra), but the far more numerous and much coarser longitudinal 
ridges give it an entirely different appearance. It is also more convex 
transversely, has less obliquely inclined parietes, more pointed apex, 
curved inner margin, and the ridge that separates the parietes from 
the intraparietes is much more strongly rounded and conspicuous. 


4, ScaLPELLUM ADUNCATUM, sp. nov. Figs. 10-138. 


Diagnosis.—Carina narrow, moderately bowed inwards, inner margin 
nearly straight, widening gradually from the apex, divided into 
parietes and intraparietes, apex very sharply pointed and a small por- 
tion of it probably projected freely, basal margin angular (about 75°). 
Tectum moderately arched transversely, ornamented with about ten 
sharply raised longitudinal ridges, all of which can be seen with the 
naked eye; one strong ridge runs down the middle, followed on each 


Fie. 10. Sealpellum aduncatum, T. H. Withers, sp.nov. External view of carina, 
x 2 nat. size. Cenomanian, upper part of Holaster subglobosus-zone : 
Oxted Lime Works, Oxted, Surrey. (B.M., I. 7235.) 
», Ll. Id. Side view, x 2 nat. size. 
;, 12. Id. Transverse section at one-third from apex, x 2 nat. size. 
», 13. Id. Transverse section at one-third from base, x 2 nat. size. 


side by two or three finer ridges, which are bounded on either side by 
a pair of stronger ridges, close together, dividing the tectum from the 
parietes. Parietes narrow, obliquely inclined from the tectum, 
concave, about half the width of the tectum, widening slowly to the 
basal margin, and ornamented with extremely fine longitudinal strie, 
which can only be seen with a lens. Intraparietes set a little inwards, 
separated from the parietes by a well-marked ridge, measuring in their 
widest part slightly more than the rest of the valve at that point, 
widening rapidly from the apex, and then narrowing rapidly until 
they reach little more than half the length of the valve, where they 


T. H. Withers—New Chalk Cirripedes. 157 


merge into the sides of the parietes, some distance from their basal 
margins. Surface of tectum and parietes ornamented with very fine 
V-shaped lines of growth. 

Holotype.—A carina (B.M., I. 7235), collected by C. P. Chatwin 
and T. H. Withers. Extreme length 19 mm., greatest breadth 4:5 mm. 

Horizon and Locality.—Cenomanian, upper part of zone of Holaster 
subglobcsus: Oxted Lime Works, Oxted,' Surrey. 

Comparison with other Species.—This species is not unlike Scalpellum 
lineatum, Darwin (1851, p. 35, pl. 1, fig. 12), but in that species the 
sides of the tectum are steeply inclined towards each other, the 
parietes and intraparietes are only separated by a very slight ridge, 
the disposition of the longitudinal ridges is different, and the inter- 
spaces are ornamented with very fine hair-like lines. It may also be 
compared with S. angustum (Dixon), (1850, Geol. Sussex, pl. xxvii, 
fig. 9), and S. hastatum, Darwin (1851, p. 37, pl. 1, fig. 13), both of 
which were founded on single carine. It agrees with S. angustum in 
that the intraparietes only reach about half the length of the valve; 
but disagrees with it in that their bases are not abruptly truncated, 
but merge into the sides of the parietes. Further, the main ornament 
is formed, not by the V-shaped lines of growth, but by the longitudinal 
ridges. From S. hastatum it differs in that the valve is much less 
recurved, has shorter and wider intraparietes, and well-marked 
longitudinal ridges. The holotype of S. hastatum (B.M., 38,462) 
was collected by W. Griffiths in the Grey Chalk (Cenomanian) of 
Dover. Unfortunately, since Darwin figured it the apex has been 
broken off and lost. 

5. ScaLpELLUM LInEATUM, Darwin. 
1851. C. Darwin, Pal. Soc. Monogr. Foss. Lepadide, p. 35, pl. ii, figs. 11, 12. 
1877. H. Woodward, B.M. Cat. Foss. Crustacea, p. 142. 

Darwin had for the description of this species, two carine, ascutum, 
and a tergum, but he assigned the two latter valves to the species 
only with doubt. Taking this into consideration, and since it is best 
that the type should be fixed, I here select the carina figured by 
Darwin (op. cit., pl. 11, fig. 12) as the holotype of S. lineatum. 

_ One of the carine was in the collection of J. Sowerby, and the 

remaining carina and the scutum in the collection of J. Morris. All 
three valves came from the Lower Chalk of Sussex. Unfortunately 
I have been unable to discover what has become of them. 

The tergum (B.M., I. 138,402) came from the Lower Chalk of 
Maidstone, Kent, and was formerly in the Bowerbank Collection. 


6. ScaLPELLUM DISSIMILE, sp. nov. Fig. 14. 
Diagnosis.—General outline of tergum rhomboidal; apex sharply 
pointed; basal angle pomted. Scutal margin straight, shorter than 
the occludent margin, about half the length of the valve. Carinal 
margin divided into two lines forming an obtuse angle, the upper 
portion shorter than the lower, and about the length of the scutal 
margin, the lower portion being about the length of the occludent 
' Exposure noticed, G. E. Dibley, ‘‘ Zonal Features of the Chalk Pits in the 


Rochester, Gravesend, and Croydon Areas’’?: Proc. Geol. Assue., 1900, vol. xvi, 
p. 492. 


158 T. H. Withers—New Chalk Cirripedes. 


margin. Surface of valve ornamented with fine, almost regular, 
longitudinal ridges, rather close together, the interspaces about the 
width of the ridges. Running transversely to these, at regular 
intervals, are about sixteen folds or ridges, which probably correspond 
to the growth-lines. -A prominent ridge extends in a straight line 
from the apex to the basal angle, dividing the valve into two unequal 
portions, the oceludent portion being the broadest. This ridge on. 
reaching about half the length of the valve bifurcates, but with a very 
narrow interspace; the ridge is very little thicker than those on the 
occludent portion, but it is prominent because the carinal portion of 
the valve lies on a lower plane than the rest of the valve, and the 
ridge on the carinal side has an almost perpendicular face. The 
longitudinal ridges, of which there are about eleven on the carinal 
portion, are flattened, the first two or three on the inside being 
bifurcated at their bases, and the interspaces very narrow. ‘Those on 
the occludent portion, numbering thirteen, are sharply rounded, and 
more pronounced, the interspaces about the width of the ridges. 
From the apex to the scutal margin runs a faint groove, from which 
the occludent margin rises up. 


Fie. 14. Scalpellum dissimile, T. H. Withers, sp. nov. External view of left 
tergum, x 4 nat. size. Turonian, Zerebratulina-zone; Gatehampton 
Farm, east of Goring-on-Thames, Oxon. (B.M., I. 8398.) 

Holotype.—A left tergum (B.M., I. 8898), collected by C. P. 
Chatwin & T. H. Withers. The specimen has its basal angle 
slightly broken. Length of valve 7°5mm., breadth 4 mm., length of 
oceludent margin 5 mm., length of scutal margin 3:5 mm. 

Horizon and Locality.—Turonian, upper part of Zerebratulina-zone : 
Gatehampton Farm,’ east of Goring-on-Thames, Oxon. 

Comparison with other Species.—This tergum apparently agrees more 
closely with S. attenuatum, H. Woodward (1906, Gzor. Mae., Dec. V, 
Vol. III, p. 352, Text-fig. 37) than any other species. The holotype 
of S. attenuatum is a tergum from the Senonian (Bel. mucronata-zone) 
of Harford Bridges Pit, near Norwich, and is in the collection of 
Dr. A. W. Rowe, who has kindly lent it to me for comparison. It is 
about three times the size of the holotype of S. dussimile. In 
S. attenuatum the longitudinal ridges, instead of being rounded and 
regular, are much flattened and vary in width on the occludent 
portion of the valve; the majority of those on the inner half are 


1 Description of section, C. P. Chatwin & T. H. Withers, ‘‘ The Zones of the 
Chalk in the Thames Valley between Goring and Shiplake’’: Proc. Geol. Assoc.,1908,. 
vol. xx, p. 394. 


A. R. Andrew—The Dolgeliey Gold-belt. 159 


broad, while on the outer half they are mostly very fine. The carinal 
portion, instead of being ornamented with slightly flattened longi- 
tudinal ridges, has extremely fine longitudinal lines. It differs 
further in other characters, the most important being that the scutal 
margin is sinuous, while it is practically straight in S. dess¢mile. 
S. dissimile may also be compared with the tergum from the 
Cenomanian (Korytzaner Schichten) of Kamajk, Bohemia, represented 
in the figure given by J. Kafka! (1886), and assigned by him to 
S. tuberculatum, Darwin. This tergum agrees in having a number of 
raised longitudinal ridges radiating from the apex, but disagrees, 
among other characters, in that the valve is not conspicuously divided 
into two parts by a prominent ridge, and in the absence of a groove 
extending from the apex to the scutal margin. 

In conclusion I wish to thank the following gentlemen for help in 
connexion with this paper: Dr. F. A. Bather, Mr. C. P. Chatwin, 
Dr. A. W. Rowe, and Mr. C. Davies Sherborn. 


1V.—Tue Geronogy oF tHE DoterttEyY Gorp-BeLtt, NortnH WaAtEs. 
By Artuur R. AnprEw, M.S&c., F.G.S. 


1. Introduction. 6. History and Statistics of Mining. © 
2. Previous Literature. 7. Lodes of the Dolgelley Gold-belt. 
3. Stratigraphy. 8. Summary of the Veins. 
4. Structure. 9. Genesis of the Auriferous Veins. 
5. Petrology. 10. Bibliography. 

INTRODUCTION. 


fq\HE town of Dolgelley lies slightly outside the main tract of gold- 
bearing country of Merionethshire, but it forms a convenient 
headquarters from which to visit the various gold-mines and auriferous 
lodes. The Dolgelley Gold-belt lies within the area covered by the 
quarter-sheets 27 N.E., 278.E., 32 S8.E., 33 N.W., 33 N.E., 338.W., 
36 N.W., 36 N.E. of the 6 inch Ordnance Survey maps of Merioneth- 
shire. It is on the north side of the estuary of the Mawddach, 
extending from the sea at Barmouth to the locality of Gwynfynydd 
on the north-east. ‘The belt forms the south-eastern flank of a range 
of high ground sloping down to the south and south-east from the 
mountains of Rhinog, Diphwys, and Garn. It is drained by several 
tributaries of the Mawddach, of which the principal are the Afons 
Hirgwm, Cwm-llechen, Cwm-mynach, Wnion, Las, Gamlan, Eden, 
and Gain. 
The rocks of the Gold-belt all belong to the Cambrian System, and 
are of two main lithological types— 
(1) The greywacke set of the Harlech Grits of H.M. Geological 
Survey. 
(2) The shale set of the Lingula Flags of H.M. Geological 
Survey: the lowest bed of the latter is usually separated out as 
a distinct zone, the Menevian. 
Previous Lirrrature. 
A considerable amount of literature has accumulated, dealing with 
the stratigraphy, paleontology, petrology, mineralogy, and also the 


1 «¢ Prispevek ku poznani cirripedi Geského ttvaru kfidového’’: Sitz. Ber. k. 
Bohm. Ges. Wiss., Prag, 1885, p. 565, pl. i, fig. 7. 


160 A, R. Andrew—The Dolgeliey Gold-belt. 


mining of the district under review. A brief résumé of this literature 
will now be given, and a full list of references will be found at the 
end of this paper. 

Stratigraphy.—The rocks of the district were first mentioned by 
Murchison (7) and Sedgwick (3), and formed part of the formations 
under dispute in the famous Cambro-Silurian controversy. Sedgwick’s 
final classification was as follows, and in so far as it applied to the 
rocks of the Gold-belt it is that accepted to-day :— 

3. Bala Group (Upper Cambrian). 

2. Ffestiniog Group (Middle Cambrian) . . (¢) Arenig Slates. 
(6) Tremadoc Slates) which form 
(a) Lingula Flags \ the Dol- 

1. Longmyndand Bangor Group (L. Cambrian) .  (¢) Harlech Grits gelley area. 
(o) Llanberis Slates. 

(a) Longmynd Slates. 

Between 1850 and 1854 the whole of this Merioneth area was 
mapped by the officers of the Geological Survey, and in 1854 appeared 
their geological maps (on a scale of 1 mile to 1 inch): these have not 
yet been revised (11). In 1866 there appeared the first edition of the 
Geological Survey Memoir of the district (12). A new edition of this 
memoir, published in 1880 (18), contained some changes in the 
classification employed. The Tremadoc Slates were separated from 
the Lingula Flags, with which they had previously been associated, 
and at the same time the term Menevian was first used by the Survey, 
for the band of black shales and slates at the base of their former 
Lingula Flags. The sequence of the Survey became— 


4. Tremadoc Slates . : A A ; Upper Cambrian. 
3. Lingula Flags , : : : : Upper Cambrian. 
2. Menevian Slates . : 5 ; : Middle Cambrian. 
1, Cambrian Grits and Flags - : Lower Cambrian. 


From 1846 to 1867 a certain amount of investigation was carried 
out, chiefly by Sharpe (16), Readwin (29), Salter (20), Plant and 
Williamson (23), Belt (24). Most of these investigations resulted in 
proposals of new classifications of the rocks, but on the whole these 
proposals have not been accepted. The chief of the investigators was 
Thomas Belt, who introduced the splitting of the Lingula Flags into 
the Dolgelley, Ffestiniog, and Maentwrog divisions—a grouping which 
is in use to-day. Belt’s sequence consisted of— 

10. Tremadoc Slates. 

8 and 9. Upper and Lower Dolgelley. 

7. Upper Ffestiniog: Tough blue-grey flags. 

5 and 6. Lower Ffestiniog: Blue and brownish-grey fine-grained flags, the lower 
part slightly arenaceous and micaceous. 

3 and 4. Upper Maentwrog: Dark-blue slates weathering rusty, the lower part 
yellowish and bluish -grey fine-grained flags, sometimes a little 
arenaceous, but not so coarse as the groups still lower. 

land 2. Lower Maentwrog: Blue-grey and blue-black jointed slates with slightly 
arenaceous flags, the lower part grey, and yellowish-grey pyritic flags 
with hard felspathic bands. 

0. Lower Cambrian, consisting of— 
(c) Menevian with Paradowxides. 
(b) Harlech Grits. 
(a) Bangor Slates. 

From 1867 to the present day, except the second edition of the 
Survey Memoir, 1881, nothing additional has been published. 


— 


A. R. Andrew—The Dolgelley Gold-beit. 161 


Within the last ten years, however, Professor Lapworth and 
Dr. T. Stacey Wilson have mapped much of the Merionethshire 
country and determined the sequence and general distribution of 
the various lithological groups of the Lower Cambrian of the region. 
Although their work has not yet been published, they permitted me 
to use their results and showed me through their succession from the 
Cefn Slate Group to the top of the Vigra Beds. The following is 
the descending: sequence of Lapworth and Wilson as employed and 
referred to by myself in the present paper :— 
9. Ffestiniog Beds of Belt. 


rs 8. Pen Rhos Beds (Upper Maentwrog of Belt): Dark-blue slates 

sae eee characteristically weathering to a bright-red or perhaps rusty 
Geological _ colour. Ae 

Survey. 7. Vigra Beds (Lower Maentwrog of Belt): Dark-grey and blue 


slates, with numerous interstratified hard beds of felspathic 

4 and siliceous material, which occur throughout. 

Menevian of (6. Clogau Beds (Menevian of Salter and Belt): Black shales and 

Survey. slates. 

5. Gamlan Shale Group: A succession of grey, greyish-green, and 
sometimes purple shales, slates, and flags, interbedded with 
occasional grit bands, which increase in number and thickness 
on going eastwards ; thickness 750 to 1200 feet. 

4. Barmouth Grits: Massive felspathic grits or greywackes with 

pebble bands ; say 600 feet thick. 

Hafotty or Manganese Shale Group (with the well-known 

! persistent zone of manganese ore at the base): Grey and 

Harlech Grits green shales and flags; to the west with rare grits; to the 

of Survey. east the grits become more frequent and eventually coarse 
and thick-bedded ; total thickness about 1000 feet. 

Rhinog Grits: Massive grits forming the Rhinog and other 

mountains ; thickness about 2500 feet. 

1. Cefn or Llanbedr Slate Group: Blue and purple shales, flags, 
and slates; to the west (Kgryn, Llanfair) with occasional 
grit bands; to east (Cefn Cam, etc.) the grits are more 
abundant, and the lowest beds (Dolwen) are red felspathic 
grits and shales. 


Paleontology.—The district around Dolgelley had always been 
considered destitute of fossils until in 1864 Readwin found 
Paradoxides Davidis, which was described by Plant (22). This, 
together with the discovery of Anopolenus and Theca, enabled the 
lower beds in which they occur to be cut off from the higher beds in 
which are found the Olenus and Lingula of the Survey. In 1866 
Plant discovered a considerable number of fossils (21-3). In 
1867 Belt’s examination led to the discovery and identification of 
many additional genera and species (24). Many fossils too had been 
discovered by the officers of H.M. Geological Survey. The following 
table contains the names of all fossils that have been discovered in the 
Dolgelley area and in the immediately neighbouring country. In 
this list ‘P’ means that the fossil was reported by Plant, ‘B’ by 
Belt, ‘S’ by the Survey. 


From the Ffestiniog Group of Belt ; the Hafod Owen of Plant. 
-B_ Conocoryphe micrura (Salt.) (from B,P,S Lingulella Davisii (McCoy). 


ise) 


bo 


Upper Ffestiniog). B Bellerophon cambrensis (Belt) 
P Conocoryphe sp. (from Upper Ffestiniog). 
B,S Hymenacaris vermicauda (Salt.). P Buthotrepis (?). 


P Olenus sp. 
DECADE V.—VOL. VII.—NO. Iv. 11 


162 A. R: Andrew—The Doilgelley Gold-belt. 


From the Pen Rhos Beds ; the Upper Maentwrog of Beit. 


B  Agnostus pisiformis (Linn.). BO. truncatus (Angelin). 
B  Olenus cataractus (Salt.). SO. sp. 
S 0. micrurus (Salt.). S  Lingulella Davisii (McCoy). 
From the Vigra Beds; the Lower Maentwrog of Belt ; the Cwm Hisen of Plant. . 
Agnostus nodosus (Belt). S Hymenocaris vermicauda (Salt.). 


Ss 
BA. pisiformis (Linn.). P,S Olenus cataractus (Salt.). 
P,S A. princeps (Salt.). S 0. gibbosus (Wahl.). 

PA. trisectus (Salt.). P Sao hirsuta. 

1Y S Lingulella Davisii (McCoy). 


From the Clogau Beds; the Menevian of Salter and Belt ; the Tyddyn-Gwladys of 


Holocephalina sp. 


Plant. 
P Protospongia fenestrata (Salt.), P Leperditia sp. 
P Dictyonema sp. (?). P,S Microdiscus punctatus (Salt.). 
P Agnostus Davidis (Salt.). P Paradoxides Davidis (Salt.). 
PA. pisiformis (Linn.). PP. Forchhammeri (Angelin). 
P A. princeps (Salt.). P,S P. Hicksii (Salt.). 
P A. trisectus (Salt.). P Lingulella ferruginea (Salt.). 
IP Area. P Obolella sp. 
P Anopolenus Henrici (Salt.). P  Obolus sp. 
P A. Salteri (Hicks). PP Theca corrugata (Salt.). 
S Conocoryphe sp. 


Petrology and Mineralogy.—References to the petrology of the 
igneous rocks of the district will be found in the writings of Salter 
(20, p. 2), Forbes (25, 26, 27), and Teall (28). 

A large number of minerals have been reported at various times 
from Merionethshire, chiefly by Readwin (80, 31), Forbes (25, 
p- 226; 27), and by Huddart (85). A list of these minerals is given 
below: unless otherwise indicated, the report of the occurrence of the 
mineral is to be found in one of Readwin’s notices. 


Native Elements: Gold, Electrum, Silver, Platinum, Platiniridium, Iridosmine, 
Copper, Lead (Forbes), Antimony, Bismuth. 

Sulphides, Tellurides, etc. : Orpiment, Stibnite, Bismuthinite, Tetradymite, Galena, 
Sphalerite, Erubescite, Pyrrhotite (Huddart), Pyrites, Chalcopyrite, Marcasite, 
Arsenopyrite, Berthierite, Tetrahedrite, Aphthonite, Polytelite (Fordes). 

Oxides: Quartz, Arsenolite, Senarmontite, Magnetite, Titanoferrite, Rutile. 

Carbonates: Calcite, Dolomite (Forbes), Ankerite (Forbes), Chalybite (Forbes), 
Rhodochrosite, Cerussite, Malachite. 

Silicates: Orthoclase, Hornblende, Uralite, Mica, Chlorite (Forbes), Ripidolite, Talc. 

Phosphates: Pyromorphite, Mimetite. 

Sulphates: Barytes (Forbes). 


Mining.—In 1844 Dean (36) and Roberts (37) published the first 
notices relating to the discovery of gold in Merionethshire. During 
the years 1870 to 1880 Readwin published many articles in the 
Mining Journal and elsewhere, giving many details of the mining 
industry (32, 33). In 1902 Maclaren (38) brought together many 
interesting facts regarding the Merioneth field. Other references 
to the mining industry of Merionethshire are to be found in the 
writings of Forbes (25), Booth (89), Huddart (35). 


STRATIGRAPHY. 


The divisions and groups which have been adopted in the present 
paper are those of Lapworth and Wilson for the Lower Cambrian and 


A, R. Andrew—The Dolgelley Gold-belt. 163 


those of Belt for the Upper Cambrian, as far as they have oeL 
generally accepted. The grouping therefore is— 
Tremadoc Slates 


Dolgelley Beds 
Ffestiniog Beds + Upper Cambrian. 


Visa Eras Pei \ Maentwrog Beds 


Vigra Beds 
Clogau Slates . . Menevian . . Middle Cambrian. 
Gamlan Shales 

Barmouth Grits 

Manganese Shales; Harlech Grits . Lower Cambrian. 
Rhinog Grits 

Cefn Slates 


The order above is in the descending sequence of the beds. Of the 
formations enumerated, those which are more intimately connected 
with the occurrence of the auriferous lodes are the Gamlan, the 
Clogau, the Vigra, the Pen Rhos, and the Ffestiniog. These merit 
more detailed notice. 

Gamlan Beds.—In the north-east part of the district, from the 
neighbourhood of the Afon Gain to near Blaen-y-cwm in the Wnion 
Valley, the lithological break between the Clogau and the Gamlan 
Beds is quite sudden, the black Clogau Slates extending down with 
all their usual characters to a basement grit (the Cefn Coch Grit), and 
the grey and grey-green beds of the Gamlan Group coming immediately 
below. In the western part, from Blaen-y-cwm to Barmouth, there is 
a more or less marked zone of transition, never more than 80 feet in 
thickness, in which there is an apparent commingling of the dark 
shales of the Clogau and the grey, green, and purple bands of the 
Gamlan. It would seem, therefore, that the grit disappears as such 
to the westward: almost everywhere, however, the boundary-line 
between the two types of Gamlan and Clogau Beds can be drawn 
fairly sharply. 

In the north-east country the thickness of the Gamlan Group is 
1200 feet, made up of intermingled grits, greywackes, flags, and 
shales. Following the outcrop of the rocks towards the south-west, 
the grits and greywackes become thinner and thinner, and the 
collective thickness of the beds less and less, until in the neighbourhood 
of the Afon Hirgwm most of the coarse-grained beds have disappeared, 
and the total thickness of the formation has become 750 feet. In this 
vicinity there is a grey flaggy bed near the top of the formation, 
characterized by the occurrence in it of good cubic crystals of pyrites, 
as much as half an inch along the edge. Traced further still to the 
south-west, the grits and greywackes become still finer, and near 
Barmouth the Gamlan Beds are seen to be made up entirely of shales 
and flags. 

The Gamlan Shales contain numerous interbedded sills of greenstone. 
Towards the west, where the group consists chiefly of shales and flags, 
the sills are thinner than they are towards the north-east, where the 
greywackes are more frequent and massive. The massive greywackes 
would offer greater resistance to the folding forces, and would tend to 
form mighty buckles with large cavities between. The softer flags 
and shales would fold and pack more readily, and would not have 


164 A. R. Andrew—The Doigelliey Gold-belt. 


rigidity enough to support massive arches. The cavities formed 
would be smaller and less continuous, and this difference would be 
represented by the difference in the size of the greenstone sills that 
we see to-day. 

Clogau Slates.—These consist of a thickness of 250 feet of well- 
cleaved slates, dark-blue and black in colour. The streak obtained 
by scratching, however, is never really black, and as the beds in 
many places are greyish blue it seems difficult to justify the epithets 
‘jet-black’ and ‘intensely black’ applied by nearly all those who 
have previously referred to them. The slates weather to a dull 
crumbly ochreous yellow colour on the surface. Their dark internal 
colouring is due to organic matter and to iron sulphide, both being 
present in greater abundance than in the correspondingly black slates 
of the Pen Rhos Beds. On analysis I found that the Clogau Slates 
contained the following :— 


Organic matter 2 5 ; : : : : 5°78 
Tron in the form of sulphide c : : : ; 21°88 
Not determined ‘ : : : : : : 72°34 

100-00 


The Clogau Slates do not give rise to surface features, and are seen 
to advantage only in the stream courses, especially in the bed of the 
Afon Gamlan, above its confluence with the River Mawddach. 
Further up the Mawddach, close to the Tyddyn-Gwladys mine, 
they cut across the river and are well exhibited. Other good 
localities are found in the course of the Bontddu stream from the 
St. David’s Gold Mill to the Pont-ty-glan-afon; in the workings of 
the Clogau lode and on the Clogau Hill; and at Aber-Amffra Harbour 
close to Barmouth, where the beds are exposed on the roadside. 

The Clogau Slates are interleaved with numerous thin pyritous 
bands, usually about 4 inch in thickness, which are rarely discernible 
at outcrops on the hillside, but are quite plain in the stream-courses. 
When fresh these bands are but slightly paler in colour than the dark- 
blue slates with which they are bedded; but on weathering they turn 
white and show up very distinctly on the smooth water-worn beds of 
the streams. ‘The cause of this peculiar weathering is probably the 
much greater proportion of pyrites contained in the white bands. 
On weathering, the pyrites sets free ferrous sulphate and sulphuric 
acid, and the latter may dissolve out some of the coloured constituents 
of the slate. 

The Clogau Slates are interbanded with many sills of intrusive 
greenstone: a few of these are massive, ranging up to 100 feet in 
thickness, but the majority are much thinner, often as thin as 2 or 
3 feet. The strike of the thinner sills is irregular: they show 
a tendency to cross a few of the planes of bedding, and then resume 
their original course. 

Maentwrog Beds——These lie above the Clogau Slates and have 
a thickness of about 2700 feet: they consist of dark-grey, dark-blue, 
and black slates and flags. There occur throughout them numerous 
bands of fine-grained siliceous grit. In the upper division of the 
Maentwrog Group, these are present only as thin wavy white layers, 


A. R. Andrew—The Dolgelley Gold-belt. 165 


from + up to 2 inches thick. In the lower divisioa, however, they 
increase in individual thickness to 2 or 3 feet, and occur as hard ribs 
sufficiently resistant to form surface features, and numerous enough 
to make up 25 per cent. of the actual thickness of the formation, as it 
is exposed in the Bontddu Glen and in the bed of the Mawddach 
River near the Cefn-deuddwr Gold Mine. The very great pre- 
dominance of these ribs in the Lower Maentwrog is the lithological 
character which has been utilized by Lapworth and Wilson in 
separating the Maentwrog Beds into— 


(6) Pen Rhos Beds or Upper Maentwrog. 
(a) Vigra Beds or Lower Maentwrog. 


(a) Vigra Beds.—The Vigra Beds are characterized by the large 
proportion of siliceous grit bands. In hand-specimens these grits 
are very fine-grained, homogeneous in texture, and light grey in 
colour; they resemble in appearance a fine-grained quartzite, and the 
similarity is increased by their extreme hardness. 

Under the microscope it is seen that these bands are even and 
compact grits, the quartz grains of which are about 35 inch in 
diameter. The visible minerals are quartz, muscovite, and a little 
felspar and pyrites. The grains of quartz are but slightly rounded, 
and a few may show crystalline faces: the quartz constitutes quite 
95 per cent. of the total bulk of the rock. The microscopic structure 
of the flagey beds in the Vigra Group is similar to that of the grit 
bands, but the flakes of muscovite are much more numerous and are 
arranged more or less parallel to the bedding. 

The shales, slates, and flags with which the grit bands are inter- 
leaved are in the main similar in lithological characters to the slates, 
etc., in the overlying Pen Rhos Beds, but the harder ribs seem to 
a great extent to have protected the shales from cleavage, with the 
result that well-cleaved slates are seldom found. The colour of these 
interbedded shales and flags is dark grey and dark blue; the 
proportion of iron in them is somewhat less than in the Pen Rhos 
Beds, and the characteristic reddish weathering of the latter is 
generally wanting. Where exposed to atmospheric agencies the 
shales and flags “weather easily from the outstanding “grit bands. 
Many of the flag gy beds and a few of the grit bands ‘weather more 
readily along certain lines which are not visible in the unweathered 
specimen, and the weathered surface becomes covered with curling 
ridges and furrows, which rather resemble tattooing. The type 
locality for these Viera Beds is on Vigra Hill, which lies immediately 
north-west of Bontddu village. Good exposures are seen along the 
road which leads from Bontddu Post Office to the St. David’s Gold 
Mill, and in the Bontddu stream parallel to this road. Other good 
exposures are in the bed of the Afon Cwm-Mynach above the 
Cambrian cottage, and in the bed of the Mawddach River upwards 
from its junction with the Afon-Eden. 

(6) Pen Rhos Beds.—The Pen Rhos Beds are 1600 feet thick. They 
consist of shales and slates, always dark blue or black in colour; they 
are well cleaved, the cleavage usually being strong enough to efface 
the planes of bedding. They contain a few bands of siliceous grit, 


166 A. R. Andrew—The Dolgelley Gold-belt. 


but compared with the Vigra Beds these are very rare indeed. 
Owing to the relative softness of the Pen Rhos Beds they do not 
form prominent surface features, except where hardened by contact 
with igneous intrusions. The dark colour is due to finely disseminated 
organic matter and pyrites, the latter of which weathers to iron oxide 
and gives the slates a characteristic red coloration on exposed 
surfaces. On fresh specimens of the slates, cubes of pyrites may be 
seen up to half an inch in size. On analysis these slates gave me 
the following :— 


Organic matter é ; é , - 5 c 3°90 
Iron in the form of sulphide .. : : . . 12°48 
Not determined ° : 3 ; : : ‘ 83°62 

100-00 


The Pen Rhos Beds are best seen on the Pen Rhos Hill opposite 
the Tynygroes Inn, 5 miles up the Mawddach Valley from Dolgelley. 
Numerous sections are also exposed in the road cuttings along the 
turnpike road from Llanelltyd to within 2 miles of Barmouth. 

Throughout the Maentwrog Group there are numerous igneous 
intrusions; these belong mostly to the so-called ‘ greenstone’ of 
H.M. Survey, but some of them are hornblende porphyries. They 
are mostly sills, with a great extent in strike and dip, but never 
more than 100 feet in thickness. 

Ffestiniog Group.—This group consists of over 38000 feet of grey 
and grey-green flags, with a few black shales and flags; they are 
hard and resistant and usually form fairly high ground. Among 
these grey and grey-green Ffestiniog Flags there are numerous 
harder ribs from 18 inches down to 1 inch and less in thickness. 
These are of two types: many of them are greywackes of medium 
grain; many are compact, fine-grained, and very siliceous grits, 
similar to those which constitute so large a proportion of the Vigra 
Beds described above. Where the shales and flags are dark-coloured 
they contain a large amount of iron, and their weathering causes 
the rock to assume reddish and dun colours. They are well seen 
along the road which runs past the mill of the Glasdir Copper Mine 
up the south bank of the Afon Las as far as Pont Llamyrewig. 
Good sections also occur in the workings and at the outcrops of the 
Glasdir Copper Mine, and the gold mine of Ffridd Goch. Many 
very massive igneous intrusions occur among the Lower Ffestiniog 
Beds, such as those forming the hills behind Penmaenpool, and 
also the heights of the Precipice Walk, Ffridd Goch, and Moel 
Cerniau. 

STRUCTURE. 


The Dolgelley Gold-belt lies on the east and south flanks of the 
well-known Harlech dome of Merionethshire. The great north and 
south sag between its two main arches, and which Lapworth and 
Wilson have followed from Moel Gedog, south of Talsarnau in a 
broken line through the Harlech uplands, continues into this country, 
and enters the Barmouth estuary close to the Caerdeon Vicarage. 
From the neighbourhood of Gwynfynydd southwards to near Llanelltyd, 
the general strike of the beds is about 10° east of north. From 


A, R. Andrew—The Dolgelley Gold-belt. 167. 


Llanelltyd westwards to Barmouth the general strike is in the main 
more north-easterly (45° or 50° east of north). This general flanking 
structure is much complicated by the minor folding to which the 
strata have been subjected. This folding has given rise to minor 
anticlines and synclines, often broken by small faults, especially along 
their axes, where, instead of gieldns to the pressure by bending, the 
strata have snapped. 

~The faults found in this district may be divided for convenience 
into two classes— 

(a) Minor faults or fractures. 
(b) Major faults or throw faults. 

The minor faults have probably been formed during the upheaval 
of the dome. They occur along those lines where the beds have 
been fractured, but where the pressure to which they have been 
subjected has not been sufficient to produce a relative displacement 
of the beds on the two sides of the fault. Among the harder beds 
of the Lower Cambrian they are especially numerous, crossing one 
another at all angles. In the beds of the Middle and Upper Cambrian 
they are not so frequent, as the strata there are not so massive, 
and have been more readily thrown into folds. ach of these fractures 
forms a noticeable groove along its outcrop. 

Of the major faults or dislocations there are two main sets, with 
a third less important set— 

1. East and west faults (practically 70° E. of N.). 
2. North-east and south-west faults (30° E. of N.). 
3. North and south faults. 

1. Hast and West Faults.—These are almost certainly older than the 
others, for they are sometimes cut and dislocated by them. The most 
conspicuous one of this east and west set is the Cwm Mynach fault, 
which cuts out a great amount of the Lower Cambrian rocks. At its 
western end it is seen in the Maentwrog Beds; going eastwards it 
increases in throw, and on the Clogau Hill it cuts out fully one-half 
of the Gamlan Beds. As the fault is traced eastwards, it decreases in 
amount, and then disappears; it cannot be seen more than 5 miles 
away from its westerly extremity. 

2. North-east and South-west Faults.—Instances of this set of faults 
are seen in the country behind Bontddu, but the displacement they 
cause is by no means large. They are probably contemporaneous with 
the north-east and south-west gold-lodes, for at Bwlchcochuchaf 
and Hafoduchaf there is a close relationship between one of these 
faults and the lodes which I describe later under these names. The 
north-east and south-west faults were formed after the east and west 
ones, as is seen in the country behind Bontddu. 

3. Worth and South Faults —These are the most recent and con- 
spicuous of the faults of the Dolgelley Gold-belt. They are found 
throughout the district, but are of greatest importance towards the 
north-east. The chief faults of this set are the following :— 

- (a) The Llynbodlyn fault of Lapworth and Wilson extends from the 
estuary at Caerdeon to Llynbodlyn on the west of Diphwys, a distance 
of about 4 miles. It cuts several lodes and causes a considerable dis- 
placement of the sedimentary beds. 


168 A. R. Andrew—The Dolgelley Gold-belt. 


(6) The Bryntirion fault is about 2 miles long: it attains its 
maximum importance on the Clogau Hill, where it intersects the 
Clogau or St. David’s lode. 

(ce) The Afon Gain fault runs along the course of the Afon Gain, 
and extends north and south from there. Its effect is greatest in the 
north, and it dies away to the south in the Maentwrog Beds, faulting 
the Gwynfynydd lode on the way. 

(d) The Beddycoedwr fault passes down the east side of Moel 
Gwynfynydd. Like its companion, the previous one, it decreases in 
intensity towards the south, dying out finally in the Ffestiniog Beds. 
It cuts out all the Pen Rhos Beds, and a small part of the Vigra Beds. 
The eastern end of the Gwynfynydd lode terminates against it. 

Cleavage.—All the finer-grained members of the sedimentary forma-: 
tions of this Dolgelley Gold-belt are traversed by cleavage planes. 
In very few cases, however, are the resultant slates of sufficiently 
good quality to be utilized for roofing or similar purposes. The strike 
of the cleavage planes is northerly; it usually les between the limits: 
of 5° west and 10° east of the meridian ; it exceeds these limits very 
rarely. The dip of the cleavage planes is always steep, from 70° to 
90°, sometimes towards the east, sometimes towards the west. The 
direction of cleavage in the gold-belt is entirely independent of the 
geological structure, as expressed in the dip and strike of the beds as 
a whole, and also of the minor puckerings and contortions into which. 
the slates have at times been thrown. It is quite possible that there 
has been movement of the country subsequent to the development of 
the cleavage, but it cannot have been of great importance. 

The movement of the country which gave rise to the cleavage must 
have been subsequent to the intrusion of the greenstone masses. In: 
several instances we find examples in which a coarse, rude cleavage: 
has been induced in the igneous rocks themselves, in the greenstone 
above the Precipice Walk, Dolgelley, and further east towards Llan- 
fachreth. Other instances may be seen near the top of Y Garn and 
elsewhere. In these cases of cleaved greenstone, the direction of: 
cleavage is the same as that of the finer general cleavage which. 
traverses the slates. I have met with one case where the greenstone 
intrusion has an included band of shale hardened to such an extent 
that it had resisted the cleaving force and has remained uncleaved. 
It is possible that it may have been more or less protected by the 
great thickness of igneous rock in which it is enveloped, but the 
conclusion remains the same—that the greenstone was there before 
the cleavage commenced. This example is seen on the Clogau Hill, 
north of Bontddu, just where the old mine tramway crosses the 
large sill which runs from Llechfraithisaf up to the top level of the 
St. David’s Gold Mine. 

Although the intrusion of the greenstone is previous to the cleavage 
of the country, I believe that it is subsequent to the folding. In 
several cases where the rocks are puckered and folded, it is seen 
that the greenstone sills do not continue uninterruptedly round the 
folds, but feather out at the actual bend of the folds, the form of 
the intrusion being here determined by the pre-existing form of the 
folding. 


A, R. Andrew—The Dolgelley Gold-belt. 169 


Again, the intrusion of the greenstone appears to be subsequent to 
the movement of the country which caused the formation of joint- 
planes. Some distance up the Bontddu stream, 200 yards above 
the St. David’s Gold Mill, a sill of greenstone is seen to end 
abruptly at a joint ; there is absolutely no trace of movement having 
taken place along this joint-plane, and of the sill being faulted off. 
It therefore seems that the joint-plane was there before the: green- 
stone was intruded, and was the determining factor in its abrupt 
termination. 

The general sequence of events in this district after deposition thus 
appears to have been—(1) folding and jointing, (2) intrusion of 
igneous rocks, (3) cleavage. In this district there is no evidence to 
show the actual geological date of origin of these separate phenomena. 
In the North Wales region generally, however, it is considered certain 
that the cleavage of the region was effected in the interval between 
Silurian and Carboniferous times. Inthe North Wales region, the 
igneous rocks found among the Ordovician beds are believed to have 
been intruded in late Ordovician or Silurian times, and the green- 
stones of the Dolgelley Gold-belt were probably intruded at- this 
time also. 

According to Ramsay, the sequence ot the movements in North 
Wales generally was—(1) intrusion, (2) folding, (8) cleavage. 
I think, however, that in the Dolgelley area the folding preceded 
the intrusion of the sills, but the point is not of great importance, 
as it is most probable that the two phenomena were closely associated, 
and took place at very nearly the same period. 


PETROLOGY. 


- Throughout the district in which the gold-bearing lodes of the 
Dolgelley Gold-belt occur, there are many intrusions of igneous 
rock, several of them of considerable magnitude. These intrusions 
occur in the form of dykes, of sills, and of more massive bosses. 
Dykes are by no means common and the only clearly defined examples 
occur in the country at the back of Bontddu. ‘The sills are found 
most frequently among the soft yielding shales. In the softest 
formation of all, the Clogau or Menevian, they are very numerous, 
and have such a considerable aggregate thickness that in places they 
‘fatten out’ the Clogau Beds by fully 50 per cent. ‘The sills 
constitute far and away the greatest proportion of the igneous rocks 
of the district; they range in thickness from tiny interbeddings 
6 inches wide, such as occur a short distance below the Vigra bridge, 
Bontddu, up to massive, almost laccolitic intrusions, 200 feet thick, 
such as form the conspicuous ridge at Llechfraith on the Clogau Hull. 
The sills continue quite evenly between the bedding planes for 
considerable distances before they die out. At times, however, they 
break across the bedding, and their intrusive and subsequent nature is 
thus clearly demonstrated. 

The metamorphic effect of these igneous intrusions upon the rocks 
with which they come in contact is not very considerable. The shales 
are baked into hard porcellanites, but only for a short distance 
(a maximum of a few feet) from the intrusions. On weathering, these, 


170 A. R. Andrew—The Doilgeliey Gold-belt. 


baked shales project from the softer unchanged shales, and also as a rule 
from the intrusive rocks themselves. The black shales are to a certain 
extent decolorized by the baking. 

I believe that in this district the 1 igneous rocks all belong practically 
to the same period. ‘There is no great diversity of lithological 
character among them, and they probably originated in the same 
common magma. ‘The petrographical character of the igneous rocks 
is difficult to determine, the metamorphic action to which the rocks 
have been subjected has been sufficient to destroy and change the 
characters of many of the minerals of which they are composed. 
There are two types of igneous rock represented in the district : 
(1) Diabase (of Harker, Teall, etce.); (2) Porphyry (of Rosenbusch). 

Among the diabases are practically all the ‘greenstones’ of 
H.M. Geological Survey. (The name ‘greenstone’ is so convenient 
for referring to the diabases that I have used it almost invariably 
throughout this paper.) The structure of the rock is intermediate 
between the plutonic and the volcanic types, though there is con- 
siderable variation and gradation in structure. The minerals that 
occur in the rock are oligoclase, hornblende, uralite, pyrrhotite, 
pyrites, chalcopyrite, calcite, sericite, kaolin, and iron oxides. Plagio- 
clase forms the most conspicuous phenocrysts in the rock; the 
erystals, rounded in outline, are twinned—chiefly albite twins; the 
plagioclase is probably a basic oligoclase close to andesine; the felspar 
phenocrysts are always cloudy, the cloudiness being due to the 
presence in them of weathering products such as calcite, kaolin, etc., 
the individuals of felspar range down in size to minute lath-shaped 
crystals, which make up a large proportion of the ground-mass of the 
rock. Hornblende is seldom seen to satisfaction, it occurs among 
the phenocrysts, where it is intensely brown and strongly pleochroic; 
usually the hornblende is completely decomposed into sericite and 
chlorite. Pyrites, pyrrhotite, and chalcopyrite are very abundant 
in the rock, but as far as my examination goes, there is no evidence 
to determine whether these minerals were originally present in the 
rock or have been subsequently introduced. Chlorite, sericite, 
kaolin, and iron oxides are found among the decomposition products 
of felspar and hornblende, but their characters call for no special 
mention. The specific gravity of this diabase rock is 2°84; it should 
be noted that the felspar is oligoclase, which is rather too acid a type 
of plagioclase to be usually found in a diabase. 

The second type of the igneous rocks of this Gold-belt is a porphyry 
or uralite porphyry; it is of much more restricted occurrence than 
the diabase, and I know of only two outcrops where fresh specimens 
may be obtained; these are at Y Garn and at Cefn-deuddwr. The 
Y Garn rock is typically porphyritic, the phenocrysts consisting of 
orthoclase, uralite, and hornblende, the latter much decomposed ; the 
ground-mass is fine-grained and microcrystalline, and is densely 
packed with little squares of orthoclase, which, like the phenocrysts, 
present only the usual characters. The only other minerals in the 
rock are muscovite, chlorite, and pyrites, produced by the decom- 
position of the hornblende; the specific gravity of the rock is 2°738. 

The Cefn-deuddwr rock differs from that occurring on Y Garn in 


R. G. Carruthers—Corat Zones in Carboniferous Limestone. 171 


the much greater size and abundance of the phenocrysts of uralite, 
hornblende, and orthoclase, and in its coarser texture; the individuals 
may be as much as 1 inch in length. The rock is composed. of 
orthoclase, plagioclase, hornblende, uralite, chlorite, magnetite, 
calcite, and pyrites. Orthoclase is found in large amount both in 
phenocrysts and in the ground-mass. In the former it often shows 
a clearly marked arrangement of concentric zones on the external 
margin of the crystal; the orthoclase is usually cloudy, owing to the 
presence of calcite. Plagioclase is present sometimes, but never to 
such an extent as the orthoclase; it is confined to the ground-mass, 
where it occurs as lath-shaped albite twins, probably andesine. 
Hornblende, like the orthoclase, occurs in two generations, among the 
phenocrysts and in the ground-mass; it is brown and strongly 
pleochroic. The bulk of the coloured constituent of the rock is 
uralite. Magnetite is a decomposition product of the hornblende, 
occurring along the cleavage cracks of the smaller hornblende crystals 
and giving a lattice-like appearance to the mineral. Pyrites may at 
times be very abundant in the rock, but often it is quite absent: it is 
perhaps of secondary origin. 

"It is to be noted that Forbes in 1868 (27) reported and described 
a uralite porphyry from this neighbourhood. 


(Zo be continued in our next Number.) 


V.—On Corat Zones In THE CaRBoNIFEROUS LIMESTONE. 
By R. G. CarruTuErs.! 


MONGST the corals collected by the Geological Survey during 
the past season, and submitted to me for determination, two 
specimens call for special remark, since they appear at first sight to 
occur out of their true zonal position. They were found by Mr. Dixon 
on the Pembrokeshire coast, to the south and south-west of Castle 
Martin. In each case Mr. Dixon gives the horizon as C,—S,, in the 
terms of Dr. Vaughan’s classification. They are, accordingly, of 
Lower Visean age. 
- One of the specimens (K.D. 12538) is referable to the genus Dzbuno- 
phyllum. In cross section there is a general resemblance to the figure 
of Dib. aff.y recently given by Mr. Douglas.? In the Pembrokeshire 
specimen, however, the mesial plate, although conspicuous, is not 
thickened in the middle, and the central area is more clearly separated 
from the septa. In vertical section the central and tabular areas are 
sharply differentiated, the former being crowded with fine vesicles 
directed inwards and upwards at a steep angle. 

The second specimen (E.D. 1350) is an example of Cyathaxonia 
rushiana, Vaugh. A cross section shows the characteristic columella, 
relatively large, oval, and with a ‘lath’ in the centre. 

Hitherto, Dibunophyllum has not been recorded in the British Isles 
below the Dibunophyllum zone (D), while Cyathaxonia rushiana has 
only been found at a still higher horizon in the uppermost Visean, 


1 Communicated by permission of the Director of the Geological Survey. 
2 J. A. Douglas, ‘‘ The Carboniferous Limestone of County Clare”’: Q.J.G.S., 
1909, vol. lxv, pl. xxvii, fig. 6 


172 R. G. Carruthers—Coral Zones in Carboniferous Limestone. 


ie. in the Cyathaxonia or Dg sub-zone. It must be remembered, 
however, that C. rushiana shows a close approximation to the well- 
known Tournaisian coral C. cornu, Mich., and that the Dibunophylla 
are not widely differentiated from many of the Clisiophyllids found in 
Lower Visean, Upper Tournaisian, and Upper Devonian beds. 

The discovery of these two fossils at a Lower Visean horizon adds 
another link to a chain of evidence bearing on the nature of the zones 
adopted for the Carboniferous Limestone. “Facts have now accumulated 
in sufficient number to warrant a brief discussion of the value of these 
zones as time indices. In this respect, without wishing to criticize 
unduly a zonal system whose application to stratigraphical problems 
has met with much success, it is nevertheless desirable that the 
limitations of the system should be pointed out. 

So far as the corals are concerned, it must be said that the zones are 
not based upon the presence of forms which are in true genetic 
sequence so much as upon a succession of unrelated faunal phases. 
They are, in fact, dependent upon a series of physical conditions (not 
of necessity expressed lithologically), each of which is favourable to 
certain gentes only. Almost invariably a gens flourishing at one 
particular level is not found in the beds immediately above or below, 
but reappears after a considerable interval in a more or less modified 
form. Abundant illustrations of such a fact are supplied by the 
distribution of the corals in the South-Western and Midland Provinces. 
Thus it is found that the gens of Cleistopora geometrica disappears 
entirely above the A zone, unless it recurs at the top of the Visean 
under the guise of Paleacis cyclostoma. Again, the gentes of Zaphrentis 
delanouet in Z,, and of Z. omaliusa, Caninia cornucopia, and Cyathaxonia 
cornu in Z, y, and C, are not again found above those zones until the 
highest Visean beds are reached. They then reappear in the D, or 
C yathasonia sub-zone in a series of mutational forms (in Waasens 
sense), whose difference from the parent stock is not great, considering 
the interval of time that has elapsed. 

The sudden and abundant appearance of Caninia gigantea in x, of 
Lithostrotion junceum, Lonsdaleia floriformis, and many other members 
of the rich Upper Visean fauna, also cannot be accounted for by any 
observed genetic connexion with immediate predecessors, but must 
probably be ascribed to immigration. It cannot be said that ancestors 
of these forms have been found in the preceding zones, although in all 
probability they are present in the Clisiophyllids and the simple and 
compound Cyathophylla of the Upper Devonian. Many other instances 
of a similar nature might be given, but their enumeration is scarcely 
necessary for our present purpose. 

The explanation of these phenomena seems to lie in an application 
of the old theory of ‘colonies’, the various gentes having lived in 
outlying areas until conditions favourable to their existence recurred, 
It is not for a moment to be denied that over a very large area, 
embracing the South-West of England, North and South Wales, the 
Midlands, and even the West of Ireland and Belgium, the sequence of 
physical conditions, and consequently of fossils, is usually in the same 
order. Sooner or later, however, local areas are met with where 
different conditions have prevailed. Consequently there is an 


A, R. Horwood—Aragonite in Middle Lias, Leicestershire. 173 


abnormal faunal phase, and difficulties of correlation immediately 
arise. ‘That is instanced in the lower part of the Rush sequence, and 
in the attempt to trace the subdivisions of the uppermost Visean, 
established in the Midland Province and in the Loughshinny coast 
section, through the totally different facies obtaining in the North of 
England and Scotland. 

The objection, therefore, to a rigid stratigraphical application of 
those corals now regarded as of zonal value, is that the present system 
is dependent on the succession of a number of forms, most of which 
are not in genetic connexion, and of whose true range in time we 
haye at present little or no conception. It must be self-evident that 
it is impossible to estimate the time value of any fossil until the 
evolution of the gens to which it belongs has been worked out, and 
the range of the various mutations ascertained. A system of zoning 
established on such lines may seem an impossible ideal, but it is 
certainly attaimable in some degree. In the meantime Dr. Vaughan 
and his co-workers have, as a rule, utilized the general characters of 
the faunal assemblage as diagnostic of any particular horizon. The 
errors caused by the introduction of species, by favourable conditions, 
at a somewhat different level in the areas concerned, are in this way 
made partially to counterbalance each other. If, in addition, the 
sequence of physical conditions, and therefore of faunal phases, are in 
agreement, then reliance can be placed on the broader aspects of the 
correlations suggested. It is in this way that the unconformity 
within the Limestone in South Wales, and the extensive overlaps in 
North Wales and Yorkshire, have been demonstrated. But the fact 
remains that the finer details of correlation must be open to question 
so long as a zonal scale has to be used in which the genetic sequence 
is so imperfect. That is so even in areas exhibiting a similar 
succession of physical conditions. Even more objection applies to 
precise correlations based on the sudden appearance of certain gentes 
that are not represented in underlying beds. And it is still more 
doubtful whether correlations, except of the most generalized kind, 
can be made by existing methods, between areas exhibiting a serious 
difference in faunal facies. In such cases, it would seem that reliable 
results can best be attained by working out the evolution either of 
the few gentes common to both areas, or of the contrasted gentes, if 
they can be found together in another region. In the meantime, it is 
by the discovery of intermediate links, such as the two interesting 
corals found by Mr. Dixon in South Wales, that a zonal scale, of 
a continuously genetic nature, may eventually be established. The 
frequent discovery of such fossils need cause no surprise; on the 
contrary, it is only to be expected during the progress of research. 


VI.—Own tHe Occurrence oF ARAGONITE IN- THE Mippite Lras oF 
LEICESTERSHIRE; WITH SOME REMARKS ON THE CALCAREOUS CHARACTER 
OF THE SPINATUS BEDS. 
By A. R. Horwoop (Leicester Museum). 
ee: Liassic strata generally are so barren of any minerals of 
importance or of an appreciable size or extent that the record 
of the discovery of one not hitherto known to occur in a crystalline 


174. A. R. Horwood—Aragonite in Middle Lias, Leicestershire. 


form, apart from the part it plays in the formation of shell-layers at 
that horizon, is assuredly of interest. Hitherto the Liassic strata have 
not yielded any minerals unassociated with shell-structure, except 
selenite, which occurs commonly in some Upper Liassic clays, whilst 
it is not unusual to find fossils converted into iron-pyrites or marcasite, 
especially at certain horizons. The Doggers of Yorkshire are note- 
worthy instances of this kind. In the Middle Lias, zine, nickel, and 
cobalt are found in the iron-ores of the Cleveland district.! 

Whilst confined hitherto, so far as I am aware, to the parts of 
shells, ete., which have not been converted into calcite—the usual 
form taken by carbonate of lime when replacing the lime secretions 
of shells of Mollusca and other testaceous animals—aragonite has now 
been discovered by the writer unassociated with organic remains in 
the Amaltheus spinatus beds of the Middle Lias, or Rock-bed, at 
Tilton Hill, near Lowesby Station, Leicestershire. 

The mineral exhibits clearly the acute pyramids characteristic of it, 
with orthorhombic crystals. Although not common it forms a mass 
about a foot square in some places the crystals being radially arranged, 
as is usually the case, with their terminations all directed to a common 
centre, in much the same way as those of quartz in the ‘ potato- 
stones’ or geodes of the Trias. But their mode of occurrence seems 
best compared with certain boulders of strontia, discovered by Mr. H. 
Bolton” at Leigh Court, near Bristol, the outer surface presenting an 
amorphous rounded exterior, characteristic of worn boulders in 
general. 

The surface of the Tilton boulders does not, like the Triassic 
boulders, present grooves. I was informed by Mr. G. W. Lamplugh 
that the Middle Lias at Barnstone presents strie, but these are 
probably not of Marlstone age, but truly Glacial (or post-Pleistocene). 
It is interesting to note that in typical aragonite a small percentage of 
strontia (4 per cent.) usually occurs. The exact horizon of these 
deposits at Tilton Hill is a few feet at most, usually a few inches, 
above the thick ‘‘encrinital limestone band’’, which occupies so 
constant a position, just below the Transition- bed, between the 
Middle Lias (spinatus-beds) and the Upper Lias. This horizon is 
a well-marked one, and may be traced all over the higher ground at 
Tilton Hill. The name ‘ encrinital limestone band’’,? adopted from 
Wilson,* is not quite correct, since encrinites do not enter into its 
composition, but, as pointed out elsewhere,*® this band is made up of 
joints and portions of stems of Crinoids, with fragments of Pecten, 
Polyzoa, and other littoral organisms, resembling in composition 
some forest marbles of the Eastern Counties, as suggested to me by 
Professor T. R. Jones. Perhaps a better name, more correct from 
a paleontological point of view, is erinoidal limestone band. The 
crinoid stems, though fragmentary, are abundant, and the horizon 


1 Vide Rudler, ‘‘ Minerals of the British Isles’’: Mem. Geol. Sury., 1905, p. 191. 

2 See Grou. Mac. , 1907, p. 471. These boulders varied in Bie: from. that of 
a pea to that of a mass 100 tons in weight. 

5 Grout. Mac., 1907, pp. 462-3. 

4 Tbid., 1886, p. 296 et seqq. 

5 Trans. Northants Nat. Hist. Soc., 1907, p. 105. 


A. R. Horwood—Aragonite in Middle Lias, Leicestershire. 175 


forms a distinct band in section, being highly calcareous, and in 
character a crystalline limestone, consisting of at least 60 per cent. of 
carbonate of lime. From its composition it is thus practically pure 
calcite. Indeed, the organic contents are mainly calcite, and the 
inorganic residue consists of a small percentage of lime, with iron 
and a little detrital matter, though in this last respect it varies 
a good deal. 

Dr. R. Brauns’ has pointed out that calcareous deposits may be 
determined in their ultimate character by the temperature of the 
solutions from which they are precipitated, calcite being formed with 
its characteristic rhombohedra in a cold solution, or one in which 
there is a preponderance of alkaline silicates, whilst a warm solution, 
and one in which gypsum or strontianite occurs, is conducive to the 
formation of aragonite. ‘he amount of concentration of the solution 
influences the direction which the carbonate of lime will take, or its 
ultimate form as calcite or aragonite. Thus Credner? has found that 
a cold saturated solution produces calcite, a warm dilute solution 
aragonite. ‘These conclusions are borne out, moreover, by the 
physical relationship between the contents of this crinoidal limestone 
and the strata above. Thus above this horizon the beds are more 
ferruginous, less calcareous, often glauconitic, and of a distinctly more 
littoral type, the chief characteristics of the fauna being Gasteropods, 
Echinoderms, and Cephalopods. These beds would thus present, when 
unconsolidated and in a state of solution, a warmer temperature, and 
because they were further from the bottom of the basin or floor of the 
sea would be less concentrated with calcareous matter, but would 
contain more alkaline silicates. Thus aragonite would here replace the 
carbonate of lime, which does not amount to as much as 50 per cent. 
And this is what is actually the case, the shells being aragonite shells, 
though not confined to the zone or organisms mentioned and more 
constant at the horizon indicated. Cephalopods, Pinna, Amusium, and 
others all have the outer original aragonite layer removed, and are 
preserved as casts, with few exceptions. In the iron-ore beds the 
percentage of lime is 62:14 per cent., with ferric oxide 25-71 per cent. 
at Caythorpe and 30 to 33 per cent. at Tilton.2 But here and elsewhere 
the percentage of lime generally in the ore-bearing rock is very much 
lower, being about 13 per cent., whilst there is 29 per cent. of carbonic 
acid. In the crinoidal limestone band, however, the constituents are 
markedly different. Of lime there isa percentage of quite 60 per cent., 
and an absence of detrital matter or ferric oxide to an appreciable 
extent. This band, moreover, marks, as I have suggested, the 
culmination of pelagic and the inset of more littoral conditions. 
In this way it would naturally have been deposited as a more or less 
concentrated solution, because nearer the bottom into which all saline 
matter collects, and a colder solution from its abyssal character. 
Moreover, pure limestone usually denotes deposition far from land, 
and in this case the pure character may be due to absence of sandy or 
argillaceous matter and undisturbed deposition of lime, whilst the 

1 Chemische Mineralogie, 1896, p. 156. 


2 Neues Jahrb., 1871, p. 288. 
3 Grou. Mae., 1907, pp. 462-3. 


176 A. R. Horwood—Aragonite in Middle Lias, Leicestershire, 


fragmentary character of the organisms may denote that the deposit, 
which is very thin but constant, owes its highly calcareous nature 
to its being an ancient sea-floor. The fragments are not rolled, but 
are broken portions that have dropped down into the abyssal depths 
from the higher zones. It seems, indeed, more natural to regard it as 
at first pelagic and gradually elevated, allowing of more littoral 
conditions above. 

The occurrence of calcite and aragonite in the same seam, which is 
found in most instances to be the case where an abundant fauna 
occurs, 1s quite in harmony with known conditions elsewhere, for in 
the hematite deposits at Cleator Moor both calcite and aragonite 
occur. 

It may be of interest here to note the distribution of calcite and 
aragonite when replacing carbonate of lime of shells of Mollusca or 
other animals. Dr. Sorby! has shown that the shells of some 
organisms are preserved as calcite, others as aragonite, whilst in some 
one portion is converted into calcite, the other into aragonite. And 
he demonstrated that certain forms—Foraminifera, Annelids, Echino- 
derms, Polyzoa, Brachiopoda, Ostrea, and Pecten—when preserved as 
fossils have their shells converted into calcite, whilst in Corals, Cephalo- 
pods, Gasteropods (except Patella, Fusus, Littorina, Purpura, ete.), 
Lamellibranchs (except Ostrea, Pecten, and the outer layer of Spon- 
dylus, Pinna, and Mytilus) the shell-layer is preserved as aragonite, 
if not removed by decomposition. Thus the shells and other parts of 
organisms from the base of the Middle Lias up to the crinoidal 
limestone band may be said to be largely preserved in calcite, 
e.g. Ditrypa, Rhynchonella, Terebratula, Pecten, and Ostrea, whilst 
Cerithium, Phasianella, Amaltheus spinatus, Tropidoceras acutum, etc., 
above are preserved in aragonite. Likewise Hodiadema granulatum, 
found above the crinoidal limestone band, when the test is present, is 
preserved in calcite, as are all the fragments of Polyzoa, Pentacrinus, 
etc., in the latter.’ 

In regard to the general character of the shell-layer in deposits of 
Liassic age generally, Sorby wrote: * ‘‘On the whole, the organic 
constituents of the coarser-grained beds of the Lias are closely like 
those of similar beds of Oolitic age, though there is a relatively less 
amount of fragments of aragonite shells and corals. By far the 
greater bulk is made up of joints of Pentacrinus, which in some cases 
constitute nearly the whole rock. Next in abundance are fragments 
of Brachiopods and oysters and shell-prisms; but Foraminifera and 
portions of Belemnites and bone also occur.’’ Further he says: 
‘Occasionally very crystalline, non-radiate, oolitic grains are met 
with, which have all the characters of re-crystallized, small, con- 
centric, aragonite concretions.” 


1 Quart. Journ. Geol. Soc., 1879, vol. xxxv, pp. 63 et seqq. 

2 See also P. F. Kendall, Grou. Mac., 1883, pp. 497 et seqq., for a further list of 
forms preserved in calcite and aragonite respectively in the Coralline Crag. His 
researches bear out in a remarkable way, as to that formation at least, those of 
Sorby, whilst in so far as my own observation has gone I am able to corroborate his 
conclusions in the case of the Middle Lias (vide supra). 

3 Thid., p. 84. 


A, R. Horwood—Aragonite in Middle Inas, Leicestershire. 177 


_ The very hard character of the crinoidal limestone band, made up 
so largely of crinoid stems, is due to the preservation of the con- 
stituents as calcite. And it is doubtless to a similar horizon that 
Dr. Sorby refers above, though there is no reason for assigning them 
in particular to Pentacrinus. In a section this band stands out some 
distance from the beds above and below, protecting the latter from 
denudation. In the quarry at Billesdon Coplow the position of this 
band is well shown, being indicated by a marked projection near the 
top of the section. The section shows, moreover, the position of 
the Transition-bed, the horizon of Hodiadema granulatum, and many 
Gasteropods. The same band is the horizon of the aragonite boulders 
at Tilton Hill. The hardness of the crinoidal band is indicated by its 
fresh surface when transported in glacial deposits, whereas the ferru- 
ginous marlstone is generally decomposed and weathered. The oolitic 
grains mentioned by Sorby as consisting of aragonite concretions occur 
in small glauconitic pockets of the Transition-bed, and upon faces of 
the jointed rock. These concretions are similar in character to those 
found—if the deposits are of carbonate of hme—in hot-water boilers, 
though aragonite alone is not found. Aragonite in a crystalline mass 
may depend upon the distribution of water in rocks, or the water-level. 
Thus W. Wallace’ found that it was only to be met with above the 
water-level in caverns in Cumberland. This is analogous to the 
distribution of aragonite as the replacing mineral in the shell-layer 
of fossil organisms. Messrs. Cornish & Kendall? found that shells in 
permeable strata had their aragonite layer dissolved out, whilst those 
protected by an impermeable layer above were preserved. To a less 
extent calcite is affected in the same way. 

In the littoral sandy, ferruginous, and readily permeable beds of 
the Middle Lias Marlstone a large percentage of the aragonite shells 
have their shell-layer dissolved away. The aragonite boulders above 
the crinoidal limestone band are similarly worn externally, probably 
by the action of water through percolation. In the first instance they 
must have been precipitated in a warm solution, and consequently at 
a period when the surface was elevated above the level at which the 
erinoidal band itself was formed. 

Aragonite is found in older calcareous rocks, chiefly Mountain Lime- 
stone or earlier rocks, in Cornwall, Devon, Dorset, Derby, Cumber- 
land, Durham, and Somerset; in Scotland at Lead Hills, Galloway, 
Seafield, Portsoy (Banff), Shetland Islands, and Orkneys; and in 
Ireland in Antrim, Derry, Down, Kerry, and MacGilligan. To these 
localities must now be added Tilton Hill,? Leicestershire. The best 
localities are Alston Moor and Cleator Moor, where there are hematite 
deposits. As a whole it is thus characteristic of the older rocks, 
when doubtless the mean thermal heat was greater than in later 
geological times. 


1 Quart. Journ. Geol. Soc., 1865, vol. xxi, pp. 413-21. 

2 «On the Mineralogical Constitution of Calcareous Organisms’’: Gxrox. Mae., 
1888, p. 66. 

3 Though so called this locality is close to Lowesby Station (G.N.R.), and must 
not be confounded with the cutting near Tilton Station (joint L.N.W.R. andG.N.R.). 
a locality more widely known than the Lowesby one. 

DECADE V.—VOL. VII.—NO. Iv. 12 


74 


178 Reviews—Professor Suess’ The Face of the Earth. 


But the opposite appears to be the case in regard to the shell- 
.ayer, i.e. of organisms preserved in part as carbonate of lime, for in 
their case aragonite shells, judging from the occurrence of casts, are 
more typical of later than earlier deposits. In this case we must 
remember that the habitat of the animal will influence the replace- 
ment of its shell as calcite or aragonite—in other words, their 
distribution depends in each epoch upon the bathymetrical range of 
the organisms. But that of the crystalline masses of aragonite found 
in caverns and cavities in other rocks depends, according to Wallace, 
upon the water-level and the temperature of springs percolating 
through the superincumbent mass; and in large measure upon the 
former secular heat of the earth’s crust. 


REVIEWS. 


I.—Tue Face or tHe Karta (Das Antlitz der Erde). By Hpuarp 
Surss. Translated by Herrua B. C. Sorzas, under the direction 
of W. J. Sortas. Vol. IV. 8vo; pp. viii, 673, with 55 illustra- 
tions. Oxford: Clarendon Press, 1909. Price 25s. net. 


ITH this fourth volume, which brings the total number of pages 

up to 2233, we have the completion of the text of Professor 

Suess’ great, and we may well say marvellous, work. To ascertain 

what is known of the main features in the structure of the entire 

globe, to systematize that knowledge, to show the influence of 

successive crust-movements on the present features of the earth’s 

surface, is but a bald account of what has been accomplished by the 

author, and admirably rendered into English by Miss Hertha Sollas, 
with the aid of her father. 

Knowledge based on the sedimentary characters and life-history of 
the formations, on the extent of land and sea areas at different epochs, 
and on the influence of volcanic phenomena is fully utilized; but the 
dominant feature in The Face of the Earth is the careful study of the 
earth-movements and foldings to which various districts from time 
to time have been subjected. Some areas, like Laurentia, show little 
or no disturbance since Cambrian times, the strata of that epoch lying 
horizontal, whereas other regions have been affected by more or less 
complex systems of folding at successive epochs, the movements being 
influenced by buttresses of older rocks that have led to deflexion and 
overthrusting. 

In the present volume attention is drawn to the arc-like curves of 
mountain chains, and also to the arcuate lines to be found among the 
Pacific islands, where the greatest abyssal depths, having the form of 
elongated furrows, lie in front of the outer border of the ares. As the 
author remarks: ‘‘ With one or two exceptions, all marine abysses 
which sink below a depth of 7000 meters are fore-deeps in a tectonic 
sense, and indicate the subsidence of the foreland beneath the folded 
mountains. Thus we are brought back to the question, whether the 
greatest deeps, like the highest mountains, are not the most recent.” 


Reviews— Professor Suess’ The Face of the Earth. 179 


With respect to deep-sea accumulations it is remarked: ‘‘ We may 
conceive that little calcareous shells sink to the bottom in great 
quantity. They are dissolved at great depths, but accumulate in 
moderate or lesser depths. In the abysses red clay is deposited only 
in trifling quantity, but on those submarine elevations which rise 
above the level at which carbonates are dissolved, accumulation occurs. 
The result is an exaggeration of the relief. Thus the depths persist, 
while the ridges increase in height, and may even grow into peaks.” 
Moreover: ‘‘ During a long period of rest not only may a great sockle 
of limestone arise, but at some remote period, when the level of the 
ocean was higher, the deposit of limestone may even have grown up 
to a height above the sea-level as it now exists. It has then been 
denuded in terraces owing to intermittent negative movement.”’ 

Concerning the views of Darwin and Dana on atolls the author 
observes: ‘‘ It must still be admitted that the depth of the enclosed 
lagoon has not yet been completely explained. Thus, the view that 
the crown has been built up by corals during positive movement has 
still some foundation.” 

With regard to the great African fractures it is remarked: ‘‘ We 
must not form too rigid a conception of such troughs, as though they 
were strips of land let down between two parallel faults. Step 
faults are to be seen on Lake Tanganyika and in the lava fields which 
lie before Mount Kenya, on the west coast of the Red Sea also, and 
more to the north on Mount Lebanon and the slopes of the Jebel 
Ansarieh. We shall form a more correct picture if we think of 
these step faults as repeated on both sides, down to the middle of the 
valley bottom—many long strips, which become wedge-shaped below, 
being let down along them to unequal depths. In this way horsts 
have been left standing within the field of subsidence.”’ 

Considering the vast extent of the area involved it is regarded as 
impossible to explain the situation from local causes, and the author 
is led to assume the existence of tensions in the outer crust of the 
earth: the phenomena being due to a rending asunder caused by 
contraction, the fissures having opened from above downwards. The 
author’s general conclusions with regard to dislocations of great 
magnitude are that they have resulted from movements caused by 
diminution in the volume of the planet. 

Great part of the present work is taken up with an account of the 
influence of the Asiatic system of disturbances on the European and 
other areas, and the structure of the Alpine regions is described in 
considerable detail. The repetition of foldings along the same lines is 
discussed, and in the course of the work the relations between the 
great geological systems in different areas are dealt with. Brittany, 
the London Basin, the Mendips, South Wales, and Malvern all come 
under notice; likewise the mountain regions of North America and 
Northern Africa, the main features of Australasia and Polynesia, the 
festoons of islands, and the mountain system of the Andes. 

In order fully to grasp the complicated structures and the sequence 
of events discussed by the author, each volume must be read steadily 
through with the aid of maps; and we are glad to learn that the 
fifth and concluding volume will comprise the plates to which reference 


180 Reviews— Professor Suess’ The Face of the Earth. 


is made in the present book, together with an index to the complete 
work. Without the index casual reference has been almost impossible, 
as the reader is confronted so often with new terms that a long search 
may have to be made before the explanations can be found. 

We are taken round the world again and again in different portions 
of the work, when the author is dealing with the movements and 
foldings of particular ages, or with diverse types of scenery; and 
throughout the work, as we have already noted, there are disquisitions 
on many other subjects of wide interest, palzeontological, lithological, 
and stratigraphical. ‘ 

In treating of ‘‘The Depths” the author discusses the subject of 
Vadose and Juvenile waters: the former being the surface, ground, 
and artesian waters; the latter being those formed during volcanic 
eruptions, from hydrogen derived from the earth’s interior combining 
with oxygen in the atmosphere. ‘‘ Thus with every volcanic eruption 
the quantity of vadose water present on the earth’s surface is 
increased.”’ 

The subject leads on to the origin of volcanoes, of ore-deposits, and 
diamond-pipes, and is followed by some account of the origin of the 
moon and the consequences of the occurrence of ‘‘ invisible mountains”’ 
beneath the earth’s surface, and the deflexion of the plummet: topics 
which we can only thus briefly mention. 

On the subject of zones and sediments there are many observations 
of interest in connexion with contemporaneous sediments which differ 
lithologically and paleontologically in different areas; but this matter 
is not free from special, and not always very familiar, terms. Thus we 
are told (p. 151) that ‘‘ purely heteropic heterotopy, i.e. a difference 
between contemporaneous formations at places remote from one 
another, always implies the existence of transitions”. Further on 
we read: ‘In most cases, it is true, the sediment and the fauna 
change simultaneously, and it is this holisopy which facilitates the 
delimitation of the stages in nature.’”? Remarks are made on the 
occurrence of perfectly white sediments in limestone formations, 
sediments devoid of the terrigenous element, and distinguished by an 
unusual abundance of organic remains. Again, we read of a stage in 
the Lias which, like that of Schlotheimia marmorata, for example, is 
only represented by a frequently interrupted crust of brown iron ore ; 
a statement which reminds us of J. F. Blake’s remark on a particular 
Ammonite zone which was locally so thin that there was no room in 
it for the zonal species. 

The highly interesting researches of Professor H. 8. Williams on 
the Devonian zones in North America and the interdigitation of 
different marine faunas receive attention. 

In the concluding chapter, after mentioning that ‘“‘ we know 
nothing of the origin of life”’, the author discusses the distribution 
of plants and animals and climatic changes, and points out that the 
view of the permanence of oceanic basins is untenable. The incoming 
of new faunas in areas not subject to great physical disturbances is 
also dealt with, and the author describes certain ‘‘ places of refuge ’’, 
remarking: ‘‘If, however, we consider carefully the actual surface of 
the earth, we shall perceive that there are tracts in which terrestrial 


Reviews— Geology of Melton Mowbray. 181 


forms of life have been protected from the action of such physical 
changes as transgressions and mountain building, for a very long 
period. There are regions which since the time of the great dis- 
turbances of the Upper Carboniferous have been practically untouched 
by such movements, and the history of these—extending over a very 
long period, as a rule from the Lower Gondwana down to the present 
day—is solely represented by the remains of successive land floras ; 
marine sediments are completely absent. It is true that in these 
places life was not exempt from the influence of climatic changes, nor 
from economic disturbances produced by the immigration of invading 
organisms, nor even from the effects of complete subsidence beneath 
the sea; nevertheless, floras followed one upon another in successive 
development, and the living world was less molested in these places 
than elsewhere: we shall therefore term them asylums.” 

We have referred to the author’s view on the diminution of the 
earth’s circumference. In his final sentences he remarks: ‘‘ If there 
were even a remote tendency in the contraction of the planet to 
establish a new, uniform radius; if the Atlantic subsidences which cut 
through our most valuable asylums, have actually been produced by 
an effort to establish planetary equilibrium; then we should have to 
fear a progressive diminution of the area inhabitable by land and 
freshwater animals. Not life itself, but a very important, and indeed 
the most highly organized, part of it would be doomed to final 
destruction, and would be restored to the pan-Thalassa. In face of 
these open questions let us rejoice in the sunshine, the starry 
firmament, and all the manifold diversity of the Face of the Earth, 
which has been produced by these very processes, recognizing, at the 
same time, to how great a degree life is controlled by the nature of 
the planet and its fortunes.” 


Il.—Memorrs oF THE GEOLOGICAL SURVEY. 


Tur Gronrocy or THE Metron Mowsray District anp Souru-Hasr 
Norrinenamsuire. By G. W. Lamptuen, F.R.S., W. Grsson, 
D.Sc., C. B. Wepp, B.A., R. L. Saertocg, B.Sc., and B. Suira, 
M.A.; with notes by C. Fox-Srraneways, F.G.S. 8vo; pp. vi, 
118, with 4 plates and 10 text-illustrations. London, 1909. 
Price 2s. 35d. 


f{\HE area here described is largely a clay-district of Red Marl, 

Lower Lias, and Boulder-clay. It extends on the south from 
Loughborough Station, Quorndon, and Barrow-upon-Soar to Melton 
Mowbray, and on the north into the Vale of Belvoir; and it is 
perhaps most widely known as a hunting country. From a geological 
point of view it includes an unbroken sequence of strata from the 
Keuper Marls to the Lincolnshire Limestone, a series largely concealed 
by the Drift deposits. 

The memoir is an explanation of Sheet 142 of the new series colour- 
printed map, which is accompanied as usual by a geological section. 
This does not show the oldest strata proved in the area, which 
comprise Coal-measures that have been reached by borings beneath 


182 Reviews—Sir A. Geikie’s Map of Scotland. 


Keuper Marls and Waterstones at Ruddington, Owthorpe, and 
Edwalton. Detailed descriptions are given of the Secondary 
formations and of the fossils and zones in the Rhetic beds, Lias, 
and Inferior Oolite. The Gypsum in the Keuper Marls, the Lime 
and Cement Works at Barnstone and Barrow-upon-Soar, and the 
Brown Iron-ore of the Middle Lias, form the chief economic products 
in the strata, and a useful map is given to show the distribution of 
the ironstone. Among the plates are good views of the hydraulic 
limestones of Barrow, of a contortion in the same formation (resembling 
a sharp anticline that was to be seen at Rugby), and of an ironstone 
working at Warnatby. 

A full account is given of the Glacial Deposits, and it is noted that 
the authors have been unable to follow the details of Mr. R. M. 
Deeley’s rather complex classification. Three types of Boulder-clay 
are, however, noted, the main Chalky Boulder-clay, a grey clay derived 
mostly from the Lower Lias, and a red silty clay derived apparently 
from the Keuper Marl. The variations in the Boulder-clay and the 
distribution of included boulders are marked on a small map. ‘The 
evidence shows that the ice-flow was mainly from N.E. to 8. W. 

The whole of the area is in the Trent drainage system. The older 
river gravel is considered to represent late Glacial flood-deposits, and 
from them remains of mammoth have been recorded. The newer 
deposits of river gravel and the Alluvium are briefly described, and 
special attention has been given to the soils on the Keuper Marl, Lias, 
and Drift. 


IIJ.—Guotoeican Map or Scorranp. By Sir Arcurparp GEIxrE, 
K.C.B., D.C.L., Pres.R.S. Scale 10 miles to an inch. Second 
edition, with Explanatory Notes. pp. 31. Edinburgh: John 
Bartholomew & Co., 1910. Price 7s. 6d. net. 


IGHTEEN years have elapsed since we called attention to the first 
edition of this map (Grot. Mae., November, 1892); and we now 
welcome a revised edition, which embodies the later published work 
of the Geological Survey. The divisions shown in the Index of 
Colours are practically the same, the Lower Silurian being now taken 
to include Arenig as well as Caradoc and Llandeilo; while the Old 
Red Sandstone, subdivided as before into Upper and Lower, has two 
colours for the lower strata, those north and those south of the 
Grampians. The principal changes in the map are in the Isle of 
Arran, where Trias replaces much area formerly coloured as Old Red 
Sandstone, in the details of Islay, Colonsay, and Gigha, in the country 
between Oban and Inverary, Rannock Moor, and Blair Athole, and on 
the borders of Sutherland and Caithness. A considerable amount of 
geological detail and much topographical information are shown with 
great clearness on the map. The accompanying explanatory notes 
have been amplified, more especially with regard to the Volcanic 
rocks, the Dalradian schists, the Downtonian, and the Old Red 
Sandstone. 


Reports and Proceedings—Geological Society of London. 1838 


REPORTS AND PROCHEDINGS. 


GroLocicaL Soctery or Lonpon: ANnuAL GENERAL MEETING. 


I. February 18, 1910.—Professor W. J. Sollas, LL.D., Sc.D., F.R.S., 
President, in the Chair. 


The Reports of the Council and of the Library and Museum 
Committee, proofs of which had been previously distributed to the 
Fellows, were read. It was stated that the number of Fellows 
elected during the past year was 64 (as compared with 52 in 1908). 
Of these, 40 paid their Admission Fees before the end of the year, 
making, with 15 previously elected Fellows, a total accession of 55 in 
the course of 1909. The losses by death, resignation, and removal 
amounted to 44 (3 less than in 1908), the actual increase in the 
number of Fellows being, therefore, 11 (as compared with an increase 
of 5 in 1908). The total number of Fellows on December 31, 1909, 
was 1294. 

The Balance Sheet for that year showed receipts to the amount of 
£3089 8s. 4d. (excluding £2000, the amount of the Sorby and 
Hudleston Bequests, and the Balance of £198 0s. 2d. brought forward 
from 1908) and an Expenditure of £3125 19s. 4d. 

The Report of the Library and Museum Committee enumerated the 
extensive additions made during 1909 to the Society’s Library, and 
gave details of the progress accomplished by Mr. C. D. Sherborn in the 
compilation and arrangement of the great Card Catalogue. 

The Reports having been received, the President requested the 
permission of the Fellows to send a telegram of congratulation to 
Emeritus Professor E. Suess, F.M.G.S., and, this permission having 
been granted with acclamation, the following telegram was immediately 
dispatched to Vienna :— 

“Professor E. Suess, Afrikanergasse, 9 Wien, II. The Geological Society, 
assembled at its Annual Meeting, sends greeting, and offers its congratulations to 


the veteran author of Das Antlitz der Erde on the completion of bis great work.— 
Sollas, President.’’ 


The President then handed the Wollaston Medal, awarded to 
Professor William Berryman Scott, F.G.S., to the American Ambassador 


for transmission to the recipient, addressing the Ambassador as 
follows :— 


Mr. Whitelaw Reid,—The Council of the Geological Society has awarded the 
Wollaston Medal, the highest honour which it can confer, to Professor William 
B. Scott, in recognition of his distinguished services to Geology, especially by his 
brilliant researches into the Mammalia of the Tertiary Era. 

It is now many years since Professor Scott learnt from our famous masters, 
Huxley and Gegenbaur, all that the old world had to teach touching the com- 
parative anatomy of the Vertebrata. Since then, by his admirable researches on 
the extinct mammals of both North and South America, he has helped to bring 
the New World into equal authority with the Old. 

More than a quarter of a century ago he undertook, in company with his friend 
Professor Osborn, those exploratory expeditions into the West of the United States 
which succeeded in exhuming from the Tertiary rocks the debris of successive 
mammalian faunas, and returned to the museums of the East laden with the spoils 
of the past. TIllumined by his genius, this material has gradually taken form, and 


184 Reports and Proceedings—Geological Society of London. 


now reveals to an admiring world the ancestral history of diverse existing mammals, 
such as the Camel, the Rhinoceros, and the Dog. 

More recently he organized an expedition into Patagonia, which, during three 
years of activity, proved equally fertile in results. These are now being set forth 

“in a series of exhaustive monographs, to which Professor Scott has already 
contributed a masterly account of the genealogy of the Rodents and of the 
Edentata. 

In his comprehensive grasp of the manifold relations which unite the great 
complex of the animal world, and by his philosophic conceptions of the course of 
organic evolution, Professor Scott ranks among the select few whom the future will 
number among the great paleontologists of the illustrious past. 

In asking you to receive this Medal for him, I beg you to assure him of the deep 
interest with which the Society follows his investigations, and to express the hope 
that he may live long to enrich our Science with discoveries no less important than 
those which we now celebrate. 


The Hon. Whitelaw Reid replied in the following words :— 


Mr. President,—I have much pleasure in appearing before this learned body, on 
behalf of my distinguished countryman, Professor Scott, to receive this Medal for 
him and in his name. 

I may venture also to assure you of his warm thanks, and of the high appreciation 
with which the great honour that you have thus conferred—the greatest within your 
gift—will be regarded by Professor Scott himself, and by the noted and very 
important institution with which he is connected—Princeton University, or ‘Old 
Nassau’, as its alumni love to call it. 

You have enhanced this honour by the cordial and gracious language in which you 
have been pleased to extend it. It is enhanced also by what I may perhaps call its 
family origin. We all know too well how family disputes are apt to be the worst 
and sometimes the most dangerous. Just so, no recognition of success is so sweet as 
that from the circle of kindred. A generous tribute like this, from the authoritative 
body of geologists in one branch of the great English-speaking family, for good 
work done by a leader in that important science in another branch of the same 
family, is peculiarly grateful to the recipient himself, and grateful also, as well as 
helpful and inspiring, to his University, to his friends, and in general to his 
countrymen. 


The President then handed the Murchison Medal, awarded to 
Professor Arthur Philemon Coleman, to the Right Hon. Lord 
Strathcona and Mount Royal, G.C.M.G., High Commissioner for 
the Dominion of Canada, for transmission to the recipient, addressing 
him as follows :— 


Lord Strathcona,—The Murchison Medal is awarded to Professor Coleman in 
recognition of his important contributions to geological science. 

During his long and distinguished occupation of the Chair of Geology in the 
University of Toronto, he has added largely to our knowledge of the history and 
formation both of the stratified systems and of the igneous rocks of Canada; nor has 
he restricted his attention to these, but has thrown much light on the origin of some 
of its most interesting scenery. He has travelled far and wide, and, bringing to 
bear the vast stores of information gathered in his journeys through North 
America, Europe, and Africa, he has increased the value of his researches by 
making use of the comparative method. The deposits of nickel ore at Sudbury have 
yielded to his investigations conclusions of fundamental importance, which have been 
recognized and enforced by the veteran author of Das Antlitz der Erde. No less 
important are the results of his researches on the Pleistocene Series in the vicinity of 
Toronto. His latest achievement—the discovery of glacial deposits in the Lower 
Huronian rocks of Canada—extends the evidence of uniformity into the remote past 
of the Protzon. 

I had many opportunities of admiring the enthusiasm and energy of Professor 
Coleman, when we were fellow-hammerers on the Dwyka Conglomerate, and it is 
with peculiar pleasure that I hand you this Medal, which I beg you to be good 
enough to transmit to him. 


Reports and Proceedings—Geological Society of London. 185 
Lord Strathcona said— 


that he was greatly honoured and pleased to be the medium of transmitting the 
Medal to Professor Coleman, on whose behalf he ventured to express his warmest 
thanks. He added that this was not the first occasion on which he had acted as 
interpreter to the Canadian branch of the great English-speaking family of the high 
esteem in which the old Motherland held the brilliant work accomplished by 
Canadian geologists. 


The President then presented the Lyell Medal to Dr. Arthur 
Vaughan, B.A., addressing him in the following words :— 


Dr. Vaughan,—The Lyell Medal is awarded to you in recognition of your 
distinguished services to Geology, especially in establishing the order of the Faunal 
Succession in the Lower Carboniferous rocks of Britain. 

In your earlier studies of the Jurassic zones with their teeming fossils, you 
acquired a mastery over the investigation of the known which enabled you to venture 
with confidence into unexplored regions. Thanks to your researches, the Avon 
Gorge, once famous for its beauty, has now become no less famous as a scale of 
geological time. 

From all sides—Wales, Ireland, France, Belgium, Germany, and remote parts of 
Britain—geologists, attracted by this long-desired means of correlation, have 
hastened on pilgrimage to Clifton, where, under your illuminating teaching, they 
haye been made familiar with all the mysteries of the new standard of reference. 

How fortunate have been the results the pages of our Journal bear witness ; our 
knowledge of the stratified crust has been enriched by a whole chapter, and the 
method of William Smith has once more achieved a triumph. 

Of your power to instruct I speak with experience, for I was your pupil when last 
I visited the Avon section; this recollection adds to the pleasure with which, in 
the name of the Council, I hand you this award. 


Dr. Vaughan replied as follows :— 


_ My. President,—Nothing could have given me greater delight, or have come at 
@ More opportune moment, than the news of the award to me of the Lyell Medal. 

With the zeal for fresh labours partly dulled by a long illness, this eagerly desired 
prize came as a welcome spur, restoring self-confidence by assuring me of the 
sympathy of brother geologists. As yet, sir, I can only hope that, some day, I may 
have done more to deserve this great honour and the kind words with which you 
have so generously accompanied its bestowal. 

My thanks are rendered heartily and, in very truth, humbly to the Council of the 
Geological Society and to the many Fellows who have so kindly approved of their 
selection. I cannot allow this unique opportunity to slip of acknowledging how 
much my work owes to the inspiring advocacy of two staunch and long-time friends, 
Professor 8. H. Reynolds and Mr. EK. E. L. Dixon. 


In presenting the Balance of the Proceeds of the Wollaston 
Donation Fund to Mr. Edward Battersby Bailey, B.A., the President 
addressed him in the following words :— 


Mr. Bailey,—The Balance of the Proceeds of the Wollaston Donation Fund has 
been awarded to you by the Council in recognition of the value of your investigations 
into the Carboniferous System of Scotland and the structure of the Glen Coe area. 
After carrying out successful investigations on the geology of East Lothian, especially 
in relation to the Glacial phenomena, the volcanic rocks, and the Coal-measures of 
that district, you, in your paper written conjointly with Mr. C. T. Clough and 
Mr. H. B. Maute on the Caldron Subsidence of Glen Coe, analysed with great skill 
a structure of remarkable complexity, and succeeded in tracing the successive stages 
of its formation, thus obtaining results which have an important bearing on some of 
the obscurer problems of volcanic and tectonie phenomena. 

The Society hopes that your powers of exact observation and imaginative insight 
may be exercised with equal success upon the new and difficult problems which again 
confront you in the West of Scotland. 


186 Reports and Proceedings— Geological Society of London. 


The President then handed to Mr. John Walker Stather, F.G.S., 
the Balance of the Proceeds of the Murchison Geological Fund, 
‘ addressing him as follows :— 


Mr. Stather,—The Balance of the Proceeds of the Murchison Geological Fund has 
been awarded to you by the Council in recognition of the services that you have 
rendered to Geology, as well by fostering a love of research among your fellow- 
citizens in Hull as by your own investigations among the Glacial Deposits of East 
Yorkshire. 

For almost a quarter of a century you have furnished inspiration to an active band 
of fellow-workers, who have worthily maintained the traditions of East Yorkshire as 
a centre of geological study. 

To your own investigations we owe a deeper insight into the intricacies of the latest 
Glacial Deposits; we have learnt to discern in them successive horizons, each dis- 
tinguished by characteristic boulders derived from different remote localities ; we are 
able to trace their extension, beyond the limits once assigned to them, even on to the 
high Chalk Wolds; and we have gained an acquaintance in detail with the drifts of 
Kirmington and Beilsbeck, which possess so great an interest on account of their 
included fossils. 

May you long continue to exercise that wisely directed energy which has enabled 
you, in the scanty leisure of a busy life, to achieve so much for our science. 


In presenting one moiety of the Balance of the Proceeds of the 
Lyell Geological Fund to Mr. Frederick Richard Cowper Reed, M.A., 
the President addressed him in the following words : — 


Mr. Reed,—<A moiety of the Balance of the Proceeds of the Lyell Geological Fund 
has been awarded to you by the Council, in acknowledgment of the services that 
you have rendered to Geology and Paleontology, especially by your researches 
among the Invertebrate Fossils of Great Britain and Ireland, Africa, and India. 

Since the publication of your first paper in 1892, memoirs and monographs have 
proceeded from your pen in an unremitting stream. Amidst work so various and 
voluminous, it is difficult, where all is good, to know what to select for special 
praise; but all will acknowledge, as enduring monuments of painstaking industry 
and exact research, your monographs on the Trilobites of Girvan, the Fauna of the 
Bokkeveld Beds, the Fossils of the Northern Shan States, and the Cambrian Fossils 
of Spiti. 

To numerous colleagues in the field you have brought the indispensable aid of 
Paleontology. ‘They will join in welcoming this award, and in expressing with me 
our best wishes for your continued success in the work of investigation. 


The President then handed the other moiety of the Balance of the 
Proceeds of the Lyell Geological Fund, awarded to Professor Robert 
Broom, M.D., to Dr. A. Smith Woodward, Sec.G.8., for transmission 
to the recipient, addressing him as follows :— . 


Dr. Smith Woodward,—The Council of the Geological Society have awarded 
a moiety of the Balance of the Lyell Geological Fund to Professor Robert Broom, in 
recognition of his work on the Fossil Reptiles of the Karoo. 

While practising medicine in New South Wales, Professor Broom found time to 
make researches into the anatomy of the Monotremes and Marsupials ; these led him 
to reflections on the origin of the Mammalia, and, in the hope of obtaining a solution 
of this question, he left Australia for Cape Colony, settling in a district where, while 
still engaged in the practice of his profession, he could collect and study the reptilian 
remains ot the Karoo. He has since been able to devote himself almost entirely to 
this pursuit, and has published a long series of memoirs which add largely to our 
knowledge of the Fossil Reptilia. 

We trust that the Karoo has still many discoveries in store for him, and that he 
may be destined to throw still further light on the predecessors of the Mammalia. 


The President then proceeded to read his Anniversary Address, 
giving first of all Obituary Notices of several Fellows deceased since 
the last Annual: Meeting, including Mr. T. Mellard Reade (elected 


Reports and Proceedings—Geological Society of London. 187 


a Fellow in 1872); Mr. J. E. Saunders (el. 1855); Dr. J. Whiteaves 
(el. 1859); Mr. H. Bauerman (el. 1863); the Marquess of Ripon 
(el. 1867); Mr. F. G. Hilton Price (el. 1872); Mr. H. M. Klaassen 
(el. 1877); Mr. W. F. Stanley (el. 1884); Mr. James Parsons 
(el. 1900); and Mr. E. Kelly (el. 1875). 

He then dealt with the Evolution of Man in the light of Recent 
Investigations. Considering first the human remains of the Pleistocene 
Epoch, he pointed out that, so far as the evidence extends, it shows 
that the cranial capacity of the human skull increases rather than 
decreases as we pass backwards in time. The oldest known human 
skulls are later than the Chalky Boulder-clay. The cranial capacity 
is merely a morphological character of unknown significance. 
Observation shows that no discoverable connexion exists between it 
and the intellectual power. 

The most recent researches in comparative anatomy emphasize the 
close connexion between Man and the Anthropoid Apes, especially 
the Gorilla and the Chimpanzee. A similar result is afforded by the 
investigations of Uhlenhuth and Nuttall into blood-relationship. 

All recent researches converge to show that the genealogy of Man 
is to be traced through the Anthropoid Apes and the Catarrhine 
Monkeys to the Lemurs. Cope’s suggestion of a direct descent from 
extinct Lemurs receives no confirmation. Primitive characters, when 
present in Man, can be better explained by regression and adaptation. 

Man probably diverged from the phylum of the Primates above the 
point of origin of the Gibbon, and not far from that of the Gorilla and 
the Chimpanzee. He owed his progress in the first place to emanci- 
pation from a forest life, and commenced his career as the ape of the 
plains. The erect attitude and the use of the hand as a universal 
instrument followed as a consequence. Ancestral Man was probably 
a social animal at a very early period, and social life afforded a stimulus 
to the development of the powers of speech. He was probably 
distinguished by great bodily strength and by the possession of 
formidable natural weapons of defence and offence. With the 
invention of weapons made by art the necessity for natural weapons 
disappeared, and a regressive development of the teeth with adaptation 
to purely alimentary functions commenced. A purely human dentition 
characterizes the Heidelberg jaw, which is the oldest known. This, 
however, still reveals in all other respects strong simian affinities. 

The growth of the brain in size and complexity might be correlated 
with the evolution and use of the hand, but to a far greater extent 
with the development of the powers of speech and the consequent 
exchange, multiplication, and co-ordination of ideas. 


The Ballot for the Council and Officers was taken, and the following were declared 
duly elected for the ensuing year:—Counciz: Tempest Anderson, M.D., D.Sc. ; 
Charles William Andrews, B.A., D.Sc., F.R.S.; George Barrow ; Professor William 
S. Boulton, B.Sc.; James Vincent Elsden, B.Sc. ; Professor Edmund J. Garwood, 
M.A.; Sir Archibald Geikie, K.C.B., D.C.L., LL.D., Sc.D., Pres.R.S.; Alfred 
Harker, M.A., F.R.S.; Robert Stansfield Herries, M.A. ; Finley L. Kitchin, M.A., 
Ph.D.; Bedford McNeill, Assoc.R.S.M.; .John Edward Marr, Se.D., F.R.S.; 
Horace W. Monckton, Treas.L.S.; George Thurland Prior, M.A., D.Sc. ; Professor 
Sidney Hugh Reynolds, M.A.; Professor William Johnson Sollas, LL.D., Se.D., 
F.R.S.; Aubrey Strahan, Sc.D., F.R.S.; Herbert Henry Thomas, M.A., B.Sc. ; 


188 Reports and Proceedings—Geological Society of London. 


Professor W. W. Watts, Sc.D., M.Se., F.R.S.; Henry Woods, M.A.; Arthur 
Smith Woodward, LL.D., F.R.S., F.1.8. ; Horace Bolingbroke Woodward, F.R.S.; 
and George William Young. 

Orricers :—President: Professor W. W. Watts, Sc.D., M.Sc., F.R.S. Vice- 
Presidents : Charles William Andrews, B.A., D.Sc., F.R.S.; Alfred Harker, M.A., 
F.R.S.; Horace W. Monckton, Treas.L.8.; Professor W. J. Sollas, LL.D., Se.D., 
F.R.S. Secretaries: Professor Edmund J. Garwood, M.A.; A. Smith Woodward, 
LL.D., F.R.S., F.L.8. Foreign Secretary: Sir Archibald Geikie, K.C.B., D.C.I.., 
LL.D., Sc.D., Pres.R.S. Zreaswrer : Aubrey Strahan, 8c.D., F.R.S. 


II. February 23, 1910.—Professor W. W. Watts, Sc.D., M.Sc., 
F.R.S., President, in the Chair. 


The following communication was read :— 


‘‘Metamorphism around the Ross of Mull Granite.” ! By Thomas 
Owen Bosworth, B.A., B.Sc., F.G.S. 


The Ross of Mull granite is a coarsely crystalline plutonic mass, 
forming the western portion of the Ross of Mull and extending over 
some 20 square miles. 

The intrusion is conspicuously later than the Moine rocks, and is 
regarded as one of the ‘newer granites’. The rock shows very little 
evidence of faulting or movement of any kind, and is traversed by 
sheets of mica-trap. The eastern boundary of the granite is a very 
intricate line of junction with typical Moine Schists and Gneisses, into 
which it has been intruded. Injection-breccias occur along the margin, 
where the granite is crowded with schist-inclusions. 

The changes in the pelitic schists are of two kinds, and are con- 
sidered under separate headings (a) and (8) below. 

(a) Impregnation.—The schists have been impregnated with the 
granite in a very intimate manner—(1) along irregular cracks, 
(2) along bedding-planes, (8) along strain-slip, and (4) along 
foliation. 

Variously banded rocks have been thus produced, which suggest 
how readily these processes, carried out on a large scale, would 
convert pelitic sediments from the state of schists into crystalline 
igneous gneisses. 

(6) Thermal Metamorphism.—In some places the pelitic gneiss in 
contact with the granite, and commonly the masses included in the 
granite, have been very highly altered. The new minerals formed are 
sillimanite, andalusite, cordierite, and green spinel; and these are 
present in such amount that their formation must have been accom- 
panied by much recrystallization among the quartz, felspar, and 
mica also. : 

Sillimanite is the most abundant new mineral, and occurs not only 
as fibrolite throughout the rock, but also in larger crystals which are 
often grouped together in prismatic aggregates. These aggregates 
weather out as conspicuous knobs, measuring about an inch across. 

Under the microscope, the sillimanite is seen to enclose large 
numbers of grains of green spinel. The~cross-sections of sillimanite 
are diamond-shaped, and show a pinacoidal cleavage; their colour 


1 Communicated by permission of the Director of H.M. Geological Survey. 


Correspondence—Dr. J. W. Evans. 189 


between crossed nicols is a very low grey, and good interference- 
figures are obtained. : 
The association of minerals in the schists is the same as that 
noticed at the margin of the Ben Cruachan ‘newer granite’ mass, 
and also at the margin of ‘newer granite’ at Netherly in Elgin. 
Tourmaline, kyanite, and staurolite also occur in the Moine Schists 
of Mull, but are in no way connected with the granite. 


CORRHLSPON DEHN CEH. 


CAPE COLONY. 


Srr,—In the review of the work by Dr. Rogers and Mr. Du Toit - 
(Grot. Mac., December, 1909, p. 561) attention was called to the 
absence of references to authorities 7 the index, not in the text. 


REVIEWER. 
March 17, 1910. 


THE MEANING OF THE TERM ‘LATERITE’. 


Srr,—In discussing the meaning of the term ‘laterite’, I have at 
least the qualification of an intimate acquaintance with the material 
to which the name was first given in the area in which it is typically 
developed. 

As I understand Mr. Scrivenor, he contends that whatever may 
have been its original signification, it has been so widely employed 
in other senses that it should be dismissed from scientific language, 
the more so as the word ‘ bauxite’ is available to replace it. 

It must be remembered, however, that bauxite is a mineral name 
indicating a substance containing approximately two molecules of 
water to one of alumina, whatever may be its true chemical constitu- 
tion. ‘he bauxite of the type locality, Baux near Arles in the south 
of France, is believed to have resulted from the action of aluminium 
sulphate on limestone, but this is only one way in which such 
a product might have been formed. 

Laterite, on the other hand, is a rock name given to a widespread 
clay-like deposit which plays a conspicuous part in the surface 
features of Peninsular India. It has recently been recognized with 
similar characters in other tropical countries, and has been shown 
by the classical researches of Max Bauer, Warth, and Holland to be 
formed by the surface decomposition of alumina-bearing crystalline 
rocks, whereby the alkalies, alkaline earths, and combined silica are 
to a large extent removed, leaving behind the free silica, the titanium 
oxide, and the oxides of alumina and iron, which have taken up 
water to form hydrates. 

This well- characterized formation obviously fequires a_ special 
designation, and what could be more suitable than the name that 
Buchanan applied to it over a century ago, and which is still 
employed in the Peninsula in the same sense in scientific, technical, 


190 Correspondence—J. W. Evans. 


and popular language. Mr. Scrivenor appeals to the usage of 
engineers, but to the best of my recollection I never heard the term 
applied to any other material by a South Indian engineer during my 
four years’ residence in the State of Mysore. 

Curiously enough, at the date of the publication of the second 
edition of the Manual of the Geology of India in 1893, no complete 
analysis of laterite from the Peninsula of India was known, and its 
characteristic chemical composition was still unrecognized. Since 
that date numerous analyses of laterites from widely distant tropical 
localities have been made. The most recent information on the 
subject may be obtained from a second paper by Max Bauer (Veues 
Jahrb. fir Min., etc., Festband, 1907, pp. 33-90), a report from the 
Imperial Institute on specimens from the Balaghat District of the 
Central Provinces of India (Rec. Geol. Surv. Ind., 1908, vol. xxxvu, 
pp. 2138-20; Bull. Imp. Inst., 1909, vol. vii, pp. 278-85), both of 
which contain full information on previous literature and analyses, 
and an interesting contribution by J. Chantard & P. Lemoine ( Comptes 
Rendus Acad. Sct., vol. cxlvi, pp. 239-42; Bull. Soc. de 0 Indust. 
Min. St. Etienne, 1909, ser. rv, vol. ix, pp. 1-37), in which are 
traced out the changes that have taken place in the formation of 
laterite on the assumption that the amount of titanium oxide has 
remained unaltered. 

As a result of the work that has been done it is found that the 
chemical composition of laterite varies within wide limits according 
to the nature of the original rock, so that it is not necessarily the 
same as that of bauxite. One feature, however, remains constant— 
the small amount of combined silica in proportion to the alumina 
present, and it is in this respect that laterites differ from clays, which 
also occur as tropical decomposition products and are sometimes 
incorrectly described as laterites. If, again, the amount of ferric 
oxide is large, it is apt to form ferruginous concretions, which are 
commonly referred to as lateritie iron ore; and if, as sometimes 
happens, the aluminium hydrate is in course of time washed away, 
an accumulation of scoriaceous iron ore may be left behind which is 
certainly not laterite, though it may be derived from it. It is 
probably this which has given rise to the misuse of the term for 
surface iron ore, which is common in some of our colonies. 

It would be difficult to conceive a stronger case for the application 
of the rule of priority than the present. The term laterite was 
applied as early as 1807 to a well-marked rock type, and has 
continued in use ever since with the same signification, which has 
been adopted by writers on tropical geology in Germany and France, 
and received the endorsement of authorities like Keyser (Lehrbuch, 
1909, vol. i, pp. 282-3). At the same time it has met with general 
acceptance in this country. Yet we are told that it must be 
abandoned because it has been wrongly employed by Colonial 
engineers who are unacquainted with the material to which it is 
properly applied. 

Joun W. Evans. 


ImpEriaL Institute, S.W. 


Obituary—H. M. Klaassen. 191 


@2 eh WeAs rea 


HENDERICUS M. KLAASSEN, F.G.S. 
Born 1828. Diep January 22, 1910. 

We regret to record the death at Croydon, in his 81st year, of 
Mr. H. M. Klaassen. He was born at Kritzum in Hanover, where 
his father was the minister of the Dutch Reformed Church. After 
the ordinary school education in his native town he was trained for 
business, and in his twentieth year he came to England, and having 
gained experience he started on his own account as a seed factor on 
the London Corn Exchange in Mark Lane. The undertaking was 
successful, so that he was enabled to retire from business in 1874. 
He then followed his natural bent toward science, and attended 
the courses of lectures on Chemistry, Zoology, and Geology at 
University College, London. His predilection for this last-named 
science was greatly stimulated by John Morris, at that time Professor 
of Geology at the College, and he was induced to join the Geologists’ 
Association in 1875, and was elected a Fellow of the Geological 
Society in 1877. 

In 1883 Mr. Klaassen contributed a paper, ‘‘On a Section of the 
Lower London Tertiaries at Park Hill, Croydon,” to the Proceedings 
of the Geologists’ Association, in which a detailed description was. 
given of the character of the beds and their fossils exposed in a deep 
cutting on the Woodside and South Croydon Railway. During the 
eighteen months the cutting was in progress Mr. Klaassen visited 
the work regularly every day, and thus secured a complete record of. 
the beds exposed, and moreover he discovered some fossil bones which 
were described by Mr. E. T. Newton, F.R.S., as in part belonging to 
a new species of mammal which was named Coryphodon Croydonensis, 
and in part to a gigantic species of bird, larger than an ostrich, which 
received the name of Gastornis Klaasseni! in honour of its discoverer. 

A second paper by Mr. Klaassen, ‘‘ On the Pebbly and Sandy Beds 
overlying the Woolwich and Reading Series on and near the Addington 
Hills, Surrey,” was contributed to the Proc. Geol. Assoc. in 1890. 

Mr. Klaassen was an earnest supporter of the Croydon Natural 
History and Microscopical Club, and he took a prominent part in 
founding a school in Croydon for the secondary education of girls in 
connexion with the Girls’ Public Day School Company. Endowed 
with a genial temperament and sound judgment he won the regard 
of numerous friends, by whom his memory will be kindly cherished. 


ROBERT MARCUS GUNN, M.A., F.R.C.S., F.G.S. 
Born 1850 (21851). Diep Dzcemerr 2, 1909. 


Mr. Guyn, who was a distinguished ophthalmic surgeon, had devoted 
his leisure during many years to the collection and study of fossils. 
Born at Dunnet, in Caithness, he belonged to the Clan Gunn, and was 
son of Marcus Gunn of Culgower, on the eastern coast of Sutherland. 


1 See E. T. Newton, ‘‘ On a Gigantic Bird from the Lower Eocene of Croydon, 
Gastornis Klaasseni, Newton’’: Proc. Zool. Soc., May 5, 1885, and Grou. Mace., 
1885, p. 362. 


192 Miscellaneous— The Darwin Centenary. 


In the reefs and low cliffs of Upper Jurassic rocks, near Culgower, 
many plant-remains occur; and these, together with other specimens 
obtained near Brora, were assiduously collected by Mr. Gunn, who had 
hoped to prepare a memoir, in conjunction with Professor A. C. Seward, 
on the fossil flora of that district. His valuable collection of Brora 
Jurassic plants had been given by Mr. Gunn, just before his death, to 
the Geological Department of the Natural History Branch of the 
British Museum. Mr. Gunn also obtained from the Old Red Sandstone 
of Achnarras, Caithness, a supposed fossil Marsipobranch fish, 
described by Dr. Traquair under the name of Palgospondylus Gunnt. 
A restoration of the remains was given in the GxrotocicaL MaGazine 
for 18938, p. 471. 

Mr. Gunn had become a Fellow of the Geological Society in 1908, — 
and his death causes a sad gap in the ranks of enthusiastic amateur 
workers. . Hi. Baw 


MISCHLILANHOUVUS. 


Tae Darwintan THeory. 

The Darwin Centenary, to the commemoration of which we called 
attention in August last (Gnot. Mac., 1909, p. 375), naturally led 
to the choice of topic in several presidential addresses delivered 
during the same year. 

This was the case in Dr. D. H. Scott’s address last year to the 
Linnean Society. He pointed to the evidence that at all known 
stages of the past history of plants there has been efficient adaptation to 
the conditions; and natural selection appears to afford the only key 
to evolution. The paleontological record reveals a relatively short 
section of the evolution of plants, and indicates that while there has 
been considerable change, there has not been, on the whole, any very 
marked advance in organization, except in such cases as the floral 
adaptations of Angiosperms. The simple forms of plants existing at 
the present day are, as arule, of a reduced rather than a primitive 
nature, and yet they may have a considerable degree of antiquity. 

Mr. B. B. Woodward dealt with Darwinism and Malacology in his 
address to the Malacological Society, 1909. He remarked that the 
Mollusca probably furnish the best means of tracing out the workings 
of evolution, as the shell, properly dissected, will yield evidence of 
the life-history of the animal. The nature of the changes in form 
during the growth of species of Cephalopods and Gasteropods was 
discussed and explained; and we are led to understand how it 
is necessary sometimes to break up an Ammonite before the species 
can be definitely determined. The address embodies the results of the 
latest researches on the subject. 

Quite recently, in commemoration. of the Jubilee of the Liverpool 
Geological Society, a meeting was held on January 11 at the Royal 
Institution, Liverpool, when Professor J. W. Judd delivered a lecture 
on ‘‘ The Triumph of Evolution ’’, justifying the selection of the topic 
by remarking that the foundation of the Society was coincident with 
the appearance of Lest s Origin of Species. 


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CONTENTS. 


I. OxtornaL ARTICLES. Page If. Reyirws. Page 

Relics of the Great Ice Age in the The Coal Basin of Commentry in 
Plains of Northern India. By gir Genial Wramce: see. be. yn ee gS 
i He)? ha Poucun, 2 .G.S., ane 18 ; EPROG we 
Geo'ogical Survey of India Os eo ewe ores 

ties Geological Society of London— 

The Geo'ogy ot the Dolgetley Gold- Marchi ONO 10s Sa Gar ea 
belt, North Wales. By AnrHur Marci oor Pepe eset fe 5,9 
R.Anprew, M.Se., F.G.8. (Con- Mineralogical Society Soot tial tee 
tinued from April Number, p- 171.) 

(With two Text-maps.) See PANNE IV. Corresponpence. 

Ree Roccils fromthe Dutton Shales. T. Crook, Assoc. R.C.S., F.G.S.  ... 238 
By F. R. Cowrrr Rexep, M.A V. Onrrvary. 

F.G.S. (Plates XVI and “XVIL. ) 211 | Charles E. Fox-Strangways, F.G.S. 235 - 
Petrology and Structure of Huelva, Alexander Agassiz, For. M.R.S. ... 238 
Spain. By A. M. Fintayson, VI. MisceLuanzous. 

M.Se., F.G.S. (Plate XVIII.)... 220 | Provence Fossil Vertebrates... 240 
Organic ee in Trias, Notting- The Mammoth Cav estern n AWS- : 

eines Byres cid: SWINNERTON, tralia qs Ansonia hig 40 } 

| D.Se., F.G.S., F ZS.  ... ... 229 | Geologists’ Assofigit®” ... ... ... 2468 


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No. V.— MAY, 1910. 


ORIGINAL ARTICLES. 


a 


I.—Retics or THE Great Ice AGE IN THE PLAINS OF 
Nortruern Inp1a.} 


By T. H. D. La Toucur, Geological Survey of India. 


T may seem strange to dwellers in this country under its present 
conditions to speak of relics of a Glacial Period being visible in 
the plains of the Ganges Valley, where the mean annual average 
temperature is about 77° F. and we all know what the maximum 
may rise to; and at the outset I must guard against misappre- 
hension by saying that I do not mean to imply, by the title 
of my discourse, that the plains of India were ever, within 
geologically recent times, covered with snow and ice. We have 
evidence, it is true, that in long distant ages, at the beginning of the 
period that saw the filling up of the valleys of the old Gondwana 
continent, part of which still exists as the Peninsula of India, that is 
to say, when the deposits of clay and sandstone, supporting a luxuriant 
vegetation, now transformed into the coal of Raniganj and other 
localities, were beginning to be laid down, the higher ground of the 
Peninsula was under snow and ice, and that glaciers descended into 
the low ground and probably sent off icebergs into the surrounding 
seas. ‘Traces of these events, which took place in what is known to 
geologists as the Talchir Period, even the old rock-floors grooved and 
striated by the passage over them of fragments of rock embedded in 
moving ice, have been found at the base of the Coal-measures in the 
Central Provinces and in Rajputana, while a bed containing striated 
and polished boulders, exhibiting unmistakable evidence of ice action, 
is known in the Salt Range of the Punjab. But with these, and with 
traces of what may prove to have been a still older ice age, of which 
Sir T. Holland brought some evidence before this Society in August, 
1908, discovered by him near Simla, I do not propose to deal on the 
present occasion. 

The period of a general lowering of temperature over the northern 
hemisphere, to which the name of the Glacial Period par excellence, or 
of the ‘‘Great Ice Age”, has been given, has left abundant traces of 
its passage over the whole of that hemisphere, wherever the conditions 
are favourable for the preservation of the peculiar features which 
denote the action of large bodies of ice. Naturally these features are 

* A lecture delivered in the rooms of the Asiatic Society of Bengal, Calcutta, on 
February 10, 1910. ; % 

DECADE Y.—VOL. VII.—NO. Y. 13 


194. ZT. H. D. La Touche—Relics of Ice Age in India. 


prominent in proportion to the accumulation of ice that took place in 
any given region. Thus they are clearly visible in all the countries 
surrounding the Pole, especially so in North America, the British Isles, 
Scandinavia, and Siberia, where there has been found conclusive 
evidence to show that, during the period of maximum glaciation, 
a huge ice-cap buried a very large part of those countries, and in 
England extended as far south as the Thames Valley. This evidence 
is rendered more conclusive by the fact that, strictly speaking, the 
last Glacial Period has not yet come to an end, but that its peculiar 
characters still-persist within the Arctic Circle, and we are therefore 
able to follow the indications of its passage step by step, from the 
edge of the great ice-sheet that even now covers the greater part of 
Greenland and the extreme north of the American continent, south- 
wards across the plains of Canada or the hills of Scotland, until we 
come upon indubitable signs of what was once the outer edge of the 
larger ice-sheet of the past. oe. 

But the Arctic Circle is not the only region that affords evidence of 
the persistence into our present humdrum times of the last Glacial 
Period. Every range of mountains that raises its crest to a sufficient 
elevation above the sea-level, provided that there is also a sufficient 
precipitation of moisture, is, as there is no need for me to point out to 
those of you who have seen the Himalaya, covered with so-called 
permanent snow and ice, the lower limit of which rises gradually 
from the sea-level as we recede from the Pole. And in each of these 
ranges there is equally indubitable evidence, indications of which may 
be followed down from the still ice-bound crests, through the valleys, 
of an extension of the ice and snow to much lower altitudes within 
quite recent times, considered from a geological point of view; so 
recent that it is quite certain that man, the most highly developed 
being on the earth, had already appeared and attained to some degree 
of culture while that period of intense cold was in progress. 

It is not my intention to enter now into a discussion of the causes 
of the Glacial Period, or of the phenomena that marked its passage, 
except in so far as the latter affect this country. As Sir Archibald 
Geikie says in his Text Book of Geology,’ ‘‘No section of geological 
history now possesses a more voluminous literature than the Glacial 
Period,’’ and to give you even the slightest idea of the theories that 
have been put forward to account for it would lead me far beyond the 
limits allowable for a single lecture. Even now geologists and other 
scientific men are not in agreement as to the true cause of this wide- 
spread refrigeration of climate, and I must only ask you to accept the 
assertion that it did take place, though I may say that in case you are 
not disposed to do so, and prefer to attribute the phenomena I am 
about to describe to a general inundation, such as Noah’s flood, or 
some similar catastrophe called by another name, you will find your- 
selves in very good company, even in scientific circles. 

In bringing forward evidence which, in my opinion, shows that 
relics of this Glacial Period are still to be found in the plains of India, 
it will perhaps be best to follow the same line of inquiry that 


1 4thed., vol. op. 1301, note. 


T. H. D. La Touche—Relics of Ice Age in India. 195 


I indicated in speaking of the great ice-sheet, and start with those 
regions where glacial conditions still prevail, the highest ranges of 
the Himalaya, that is to say, and see what are the peculiar physical 
features that accompany a lowering of the temperature. The first of 
these is a former extension of the glaciers far beyond their present 
limits. As a glacier moves it carries on its surface or embedded in the 
ice huge accumulations of loose material fallen from the hill-sides 
rising above it, and at its snout, where the ice melts, deposits this 
material in an embankment-like heap, known as its terminal moraine, 
just as a gang of coolies builds up a railway embankment. If then 
the glacier retreats, this embankment will be left behind as a sign of 
the former extension of the ice. In many of the Himalayan valleys 
remains of these ancient moraines have been found as low down as 
7000 feet, whereas the present limit of the glaciers varies from 
11,000 to 18,000 feet. General MeMahon records the existence of an 
old moraine near Dalhousie, in the North-West Himalaya, at an 
elevation of about 4740 feet above the sea.’ 

But these ancient moraines are not the only indication that the 
glaciers were at one time of far greater size. In some cases smoothed 
and scratched surfaces of rock on the valley sides, far above the 
present level of the ice, bear witness to its former depth. The 
striking contrast between the U shape of a valley which has once 
been occupied by a glacier, and the V shape of the valley below, so 
characteristic of the inner Himalaya, even where old moraines are 
absent, affords further proof in the same direction. 

But, as I remarked before, we have no evidence that any of these 
glaciers ever descended as low as the plains of India, though an 
bubhtsiastic glaciologist, Mr. Theobald, once a member of the 
Geological Survey, thought that he had obtained such evidence in 
Kumaon, in the shape of old moraines, and on the plains of the 
Potwar, an elevated tract of country lying north of the Salt Range, 
between the Jhelum and the Indus.? We must look for the evidence 
which I now wish to place before you in another direction. 

One of the most striking features of the tracts that lie in the 
immediate neighbourhood of the snows is the absence of vegetation. 
Although those who have done no more than make a trip to one 
of the more accessible glaciers may be charmed by the sight of 
forests of pines or birches flourishing in close proximity to the ice, 
and with the grassy sward clothed with flowers that cover even the 
moraines, a climb of a few thousand feet will bring them to a region 
where not even a blade of grass is to be found, and the only 
vegetation met with consists of mosses, lichens, and a few of the most 
hardy flowering plants. One result of the absence of vegetation is 
that the agents of disintegration of the rocks have full play. The 
constant fimgarein one of temperature, for even at these altitudes the 
sun by day has great power, the alternate freezing and melting of 
water in the pores and interstices of the rocks, the violence of the 
wind, and the almost constant precipitation of moisture, all combine in 

1 Records, Geol. Surv. Ind., vol. xv, p. 49. 


* Tbid., vol. vii, p. 86; vol. X, pp. 140, 223; vol. xili, p. 221. See also A. B. 
Wynne, ibid., vol. xi, p. 150 ; vol. xiv, p. 15847 


196 Z.H. D. La Touche—Relics of Ice Age in India. 


rotting away, if I may so express myself, and breaking up the rocks 
with great rapidity, in comparison with tracts where the roots of grass 
and trees hold together and form a protective covering of soil. At 
these altitudes many of even the highest peaks are almost buried 
under an accumulation of their own debris, so much so that it is 
sometimes possible to ascend to heights of 20,000 feet or so with no 
more discomfort than is caused by the difficulty of breathing in 
a rarified atmosphere. This loose material is always in a state of 
more or less unstable equilibrium, and when lying on steep hill-slopes 
is constantly liable to be precipitated into the valleys, especially when 
it is saturated with moisture by melting snow or rain. When this 
happens in a tributary valley, the semi-liquid mass moves irresistibly 
downwards as an avalanche of mud mingled with boulders and 
fragments of rock, and on reaching the valley of the main stream or 
river, spreads itself out as a conical fan, radiating from the mouth of 
the tributary. In all the valleys of the higher Himalaya these fans 
can be seen in actual process of formation, and they may sometimes be 
met with even at elevations well below the snow-line, when the head 
of the tributary stream reaches up to a sufficiently high altitude. 
When the side-streams are close together the fans often coalesce, 
forming a more or less continuous terrace along the banks of the 
main river. 

If we now follow the larger valleys downwards, we find that, when 
we reach altitudes of say 7000 feet or less, exactly similar cones or 
fans occur along each bank wherever the main stream is joined by 
a tributary, but that these fans bear every sign of great antiquity, in 
proportion to their distance from the snows. Not only are they 
covered by vegetation and usually cultivated, but they are often 
selected: as sites for villages, on account probably of the ease with 
which water can be obtained by leading channels from the side- 
stream. (I have also noticed this propensity in the Alps, where in 
the main valleys each fan will have its well-watered little town built 
upon it.) This shows that no fresh material has been spread over the 
fans within recent times. Moreover, the stream that originally 
formed them, instead of flowing in devious rivulets over their surface 
as it did at first, has now cut a single deep channel directly through 
the centre, so profound in most cases that it is evident that a very 
long time has elapsed since the stream ceased to construct the fans. 
Lower down still the whole of the valley is found to be choked with 
a great thickness, often as much as three or four hundred feet, of loose 
deposits continuous with and similar to those forming the cones, out 
of which the river has cut great terraces, now on one side and now on 
the other, with a perpendicular face towards the river. Sometimes 
only small remnants of these terraces are now left, but at other 
times they form large level plateaus, on which considerable towns 
may be built. 

The origin of these terraces has aroused some discussion among 
eeologists, for it is evident that they are now being washed away by 
the rivers that once deposited them, and that, being high above the 
present. flood-level, there must have been a great change of conditions 
of some kind since that time. Changes of level, either resulting from 


T. H. D. La Touche—Relics of Ice Age in India. 197 


a recent elevation of the mountains or a depression of the plains, 
causing an increased fall, and consequently higher velocity and 
greater erosive power in the rivers, have been evoked in order to 
account for the facts; but a visit to any of the valleys will show that 
the loose material of the terrace cliffs extends in most cases down to the 
present water-level, and it is evident therefore that the existing valleys 
must have been excavated to their present depth before the terraces 
were deposited in them. In other words, that the configuration of 
mountain and valley was much the same before the terrace-forming 
period as it is now, and that since that period the rivers have been 
able to do little more than clear out their old channels. There may 
have been some elevation of the inner Himalaya during the course of 
these events, but the diminution of the burden thrown into the 
rivers, due, as we have seen, to the reclothing of the hills with 
vegetation on the retreat of the ice, is quite sufficient, I think, to 
account by itself for the change from deposition to erosion. 
A depression in the Indo-Gangetic Valley, which by increasing 
the gradient would also increase the erosive power of the rivers, 
seems equally out of the question; for, as we have seen, the 
excavation of the river-valleys took place before the terrace-building 
period, and the material removed from them must have filled up the 
depression as quickly as it was formed, even if the addition. of this 
weight on the rocky floor below the plains did not actually cause the 
depression, as some have supposed. In any case, there is nothing to 
show that during the terrace-building period the hills and plains did 
not stand in much the same relation to each other as they do now. 

Even at the present day it is sometimes possible to find the 
conditions of the terrace-building reproduced at quite low levels 
among the hills. Owing to the recent immigration of Nepalese 
cultivators into Sikkim, the forests that once clothed the hill-sides in 
that very jungly country have to a great extent been cut down, and 
the natural consequence is that landslips are very common. One 
striking instance of this I came across in the valley of the Rangpo, 
a large tributary of the Teesta north of Kalimpong. The forest on 
the north bank of this river has been almost entirely cleared off, and 
owing to the steepness of the hill-slopes and to some peculiarity in 
the le of the rocks, an almost continuous line of landslips, extending 
for several miles, has taken place. These have thrown an enormous 
quantity of debris into the river, which is unable to carry it away at 
once, and the bed of the river is thus being rapidly raised, the water 
flowing in numerous channels over the surface of the deposits. If 
now the forest were to grow up again and the landslips cease, the 
supply of material would come to an end, and the river would at 
once begin to cut for itself a defined channel through the accumulation 
of loose stuff in its bed, and as it wound from side to side would 
leave terraces on either bank, and this without our having to imagine 
any increased velocity in the stream due to increase of gradient. 

The terraces I have described are not confined to the valleys of the 
Himalaya, but are to be found all round the northern limits of the 
Peninsula, from Assam on the east to Baluchistan on the west. 
Even in this latter country, now so extremely arid, they attain to 


198 7. H. D. La Touche—Relics of Ice Age in India. 
large dimensions, much larger than the puny streams of that country 
could now account for. 

In following down the valleys we have seen that the features 
peculiar to the upper, still glaciated regions are reproduced at the 
lower levels, but that the causes that led to the production of these 
features at these lower levels have now passed away. What is more 
likely to have been the cause of these similar phenomena than a 
similarity of conditions, that lowering of temperature and consequent 
increase in the power of the erosive agencies which we call the Glacial 
Period; one which we know to have occurred in times geologically 
recent, but long enough ago to account for the erosion that has since 
taken place ?. 

It remains now to extend the argument to the plains of India, but 
it is not to be expected that the evidence in this region will be of so 
convincing a character as that afforded by the Himalayan valleys. 
There is some direct evidence, it is true, that the plains participated, 
as was only natural, in the general refrigeration of climate afforded by 
the fact that a large number of Himalayan plants are found on the 
higher hills and plateaus of the Peninsula, and that, as I am informed 
by Dr. Annandale, of the Indian Museum, a small portion of the 
fauna of Parasnath Hill in Bengal is of a type peculiar to the 
Himalaya; showing that the temperature of the intervening plains 
must have been lowered sufficiently, and that for a long enough 
period, to allow these plants and animals to wander so far to the 
south. But this evidence is not of the character that I am dealing 
with at present. Since the ice and snow did not actually descend to 
the plains, their influence on the deposits of the latter can only have 
been of a secondary character, and to a great extent these must have 
been obliterated by the divagations of the great rivers, so that only 
the merest relics now remain. 

Throughout the valley of the Ganges and its tributaries patches of 
what is known as the ‘older alluvium’ are to be found, rising to 
a considerable height, often as much as 100 feet, above the present 
flood-levels. This alluvium is generally to be distinguished from the 
later river-silts by its red colour, which has given the name of 
Rangamati, ‘coloured earth,’ to so many villages in Bengal and 
Assam; and by its containing quantities of the peculiar nodular form of 
limestone known as ‘kunkur’, the presence of which is in itself a sign 
that the deposits are of considerable antiquity, for it owes its origin 
to the slow accretion of particles of carbonate of lime dissolved out 
of the slightly calcareous sediments by percolating water, and re- 
deposited in the form of nodules as the water evaporates. 

One of the most conspicuous instances of this old alluvium is the 
elevated tract known as the Madhupur Jungle, extending to the north 
of Dacca between the present channel of the Brahmaputra and its old 
course into the Meghna. The soil of this tract is a stiff red clay, 
evidently an old river-silt, but raised to a height of some 60 to 100 feet 
above the flood-levels of the rivers on either side. Several other 
patches occur in the lower Ganges valley, but as we ascend the river 
and its tributaries into the United Provinces and Bundelkhand, we 
find that. this older alluvium is almost universally distributed, and has 


T. H. D, La Touche—Relies of Ice Age.in India. 199 


a distinctive name, that of ‘ bhangar’ in contrast with the low-lying 
‘khadar’ or straths along the river-courses, and that it bears every 
sign of being in a state of rapid erosion; that it belongs in effect to 
a condition of things that has now passed away, when the rivers 
probably possessed a much greater volume of water and brought down 
correspondingly greater quantities of silt. 

Now we have seen that it is possible, indeed quite certain, that 
during the Glacial Period exceptionally immense quantities of debris 
were precipitated into the rivers, more indeed than they were able to 
carry away comfortably, as the terraces in their upper valleys show. 
Is it not, then, reasonable to suppose that it was then that the lower 
valleys of the same rivers were choked with a superabundance of silt, 
and that to this same period it is that we must attribute the formation 
of the ‘older alluvium’; that, in fact, these deposits are as truly 
relics of the passage of the Glacial Period as the ancient moraines 
among the hills ? 

It is always a source of satisfaction to the geologist, or indeed to 
any scientific man, when he finds that a theory intended to explain 
a certain series of facts can be used to clear up difficulties that may 
surround another series of equally well-ascertained facts. The changes 
of the courses of the rivers of Lower Bengal have for a long time 
exercised the minds of surveyors, engineers, and geologists, and various 
explanations of them have been put forward, especially of the com- 
paratively sudden desertion by the Brahmaputra of its old channel, 
which ran to the east of Dacca at the beginning of the last century. 
This problem was first seriously attacked by Mr. Fergusson fifty 
years ago,’ and partly turns on the question of the origin of the 
elevated tract of ground I have already mentioned, the Madhupur 
Jungle. He attributed it to a special upheaval of that part of the 
delta which deflected the Brahmaputra into the Meghna and the 
jheels of Sylhet. But we should have to apply the same reasoning to 
other patches of the older alluvium, and it is difficult to suppose that 
each of them is due to a special upheaval; moreover, one would 
think that an upheaval in that particular place would be more likely 
to force the Brahmaputra westwards than deflect it to the east. Nor 
does it account for the fact that the Brahmaputra, now a much larger 
river than the Ganges, allowed itself to be pushed aside in this way ; 
or that, considering that it brings down very much more silt than the 
Ganges, it should have done so little towards filling up the Sylhet 
jheels. But a study of the present river-courses will, I think, throw 
some further light on the subject. 

The Dihang, which it is now universally admitted brings down the 
waters of the Tsanpo of Tibet into the Brahmaputra, is not, I think, 
the original main channel of the latter, but was, until quite recent 
times, a mere tributary. It is only within the last thirty years that 
it has been proved beyond doubt that the Tsanpo is connected with the 
Brahmaputra, though Rennell was the first to recognize that it must be 
so in 1765.” Only a few days ago I saw a modern atlas in which the 


1 Quart. Journ. Geol. Soc., vol. xix, p. 330. 
2 Memoir of a Map of Hindoostan, London, 1792, 2nd ed., p. 356. 


200 7. H. D. La Touche—Relics of Ice Age in India. 


Tsanpo was shown as flowing on eastwards into the Salween. Now it 
is not at all unlikely that, at the period I have been speaking of, the 
Tsanpo either flowed westwards, as Burrard and Hayden maintain, 
and escaped through the Himalaya at some other point, or lost itself 
in the deserts of Tibet, and that then the Dihang was a mere 
tributary of the Brahmaputra, but that it has since cut back at its 
head into the valley of the Tsanpo and ‘ beheaded’ it. If this was so, 
the Brahmaputra must have been a comparatively small river at that 
time, and it is not surprising that in its lower course it was pushed 
aside by the alluvium brought down by the Ganges and its tributaries. 
Indeed, it may be that the Madhupur Jungle isa relic of the old delta 
face of the Ganges, and that to the east of it, at that time, there was 
open water, reaching perhaps up to the foot of the Khasi Hills; in 
this way I would account for. the backward state of that part of the 
delta. But when the Dihang beheaded the Tsanpo, and brought down 
this enormous accession of water, the Brahmaputra began to assert 
itself. At first it could do little, for the accumulation of alluvium 
in its path was too great to be swept away, and it had to be content 
with its old course into the Meghna; but it had a treacherous ally 
in the Teesta, which had gradually been sapping the defences of 
the Ganges. The Teesta, wandering from side to side over the old 
alluvium south of its exit from the hills, swept it away by degrees, 
wearing down the face of the country to the west of the Madhupur 
Jungle, and in course of time opened a passage for the spill-water of 
the Brahmaputra down the Jennai River. Finally the Teesta, frankly 
deserting its lawful sovereign, the Ganges, threw itself suddenly (this 
happened so recently as 1787) into the Brahmaputra. The effect of 
this was not at first noticeable, but it is probable that the extra silt 
brought down by the Teesta was too much for the Brahmaputra to deal 
with, hampered as it was already by the damming back of its waters 
by the Meghna as the latter slowly raised the levels of Sylhet, and 
that the two allied rivers were compelled to find a new channel. 
The insignificant Jennai offered the means of escape, and its bed was 
occupied about one hundred years ago, 

The struggle that then began between the Brahmaputra and the 
Ganges is still in progress, and issue was joined so recently, almost 
within the memory of men now living, that we cannot suppose that it 
has yet been fought to a finish, or that developments may not take 
place that will have far-reaching effects upon the future history of 
Bengal. The Brahmaputra, being the more powerful river, is not 
likely to rest content with the advantage it has already gained. Up 
to the present time, indeed, it has not been able to exert its full 
strength, for it cannot do so until it has brought the level of the 
Assam Valley to the state in which it would have been had the 
valley been originally excavated by a river of the size and power of 
the present Brahmaputra. As it is, much of the force of the river 
when in flood is spent in the low ground flanking its course; but 
when this has been brought to the true ‘regimen’, there is no doubt 
but that the river will be able to show its real strength with more 


1 Geogr. and Geol. of the Himalaya Mountains, Calcutta, 1907, pt. iii, p, 155. 


A. R. Andrew—The Dolgelley Gold-belt. 201 


effect in its lower course. Even in 1838 it had succeeded in damming 
back the Ganges to such an extent near the confluence that the latter 
was fordable at several places above Goalundo, and was compelled to 
seek for a new exit to the sea. The Garai, which leaves the Ganges 
at Kushtia, was enlarged from a mere creek unable to float a vessel 
drawing more than a foot or two of water, as Rennell found it in 1764, 
to a broad and deep river, now the principal steamer-route from 
Calcutta to the Upper Ganges. What further developments may take 
place we cannot predict, but it is possible that their influence may be 
felt still higher up the Ganges, and may even extend to the Jalangi or 
the Bhagirathi, and so affect the welfare of Calcutta. The mitigation 
of any evil effects these changes may have is a matter for the 
consideration of engineers. If they become acute, something might 
be done to assist the Ganges by inducing the Teesta to return to its 
old allegiance; but the forces exerted by such vast bodies of moving 
water are so prodigious that it is unsafe to speculate without 
a complete knowledge of the facts. 


IJ.—Tue Gronocy or tar Dotcentey Gorp-Bett, Norra Waters. 
By Arruur R. Anprew, M.Sc., F.G.S. 
(Continued from April Number, p. 171.) 


History Anp Sraristics oF GoLD-MINING IN THE J)oLGELLEY AREA. 


T is believed that the ancient Britons and the Welsh were fully 
aware of the precious metal which lay among their hills. Three 
Welsh chieftains are known to have possessed chariots of gold, and it 
is inferred that this gold was derived from mines which the Welsh 
worked at an early date. Many gold ornaments have from time to 
time been unearthed, and as their style differs entirely from that 
customary at the early Christian period, they are believed to belong 
to a time long anterior to that of Christianity. Again, it is known 
that the Romans under Julius Cesar worked minerals in various parts 
of Britain, and there are many evidences of Roman mine-workings 
where gold must have been the principal, if not the sole, object of 
search. One of the most remarkable of these is outside Merioneth- 
shire, at Gogofau, near Pumpsaint, in Carmarthenshire, where the 
traces of Roman occupancy are undoubted. Another locality, this 
time in Merionethshire, is reported by Ramsay (12, p. 64) as on the 
banks of the Allt-y- Wenallt. 

Coming nearer to the present, it is well to mention the belief of 
Readwin (81, p. 1) that gold was worked in Wales during the reign 
of Charles I. The facts on which Readwin bases his belief are as 
follows :—Thomas Bushell, between 1631 and 1645, rented royal 
mines in Merionethshire, near Barmouth ; in 1636 he erected a mint 
at Aberystwyth, ostensibly to coin silver coin; he also coined £3 
pieces and other gold pieces; Bushell gave and lent to Charles I 
some two anda half millions of our money ; his was the only mint 
at the time not under the control of the Parliamentary forces, and 
thus able to supply the Royalists; Bushell could not have imported 
the gold into Wales, for he was hemmed in by the Parliamentary 


202 A. R. Andrew—The Dolgelley Goild-belt. - 


forces. Readwin thinks that Bushell worked the mines chiefly for 
gold; that he paid Charles one-tenth as royalty, and lent him nearly 
all the remainder, and that it was not in the interests of either to 
say anything about it. 

At any rate, whether Bushell really worked gold or not, all know- 
ledge of the existence of the precious metal in Merioneth was lost, 
and it was not until quite recent times that any more was heard of its 
occurrence. The honour of the discovery or re-discovery was claimed 
by four persons, of whom Mr. Arthur Dean was, at any rate, the first 
to publish any definite account ; in 1844 he read a paper before the 
British Association (86) on the existence of gold at Dol-y-frwynog. 
Mr. Robert Roberts, of Dolgelley, however, claimed that he had 
discovered gold at Cwm-heisian in 1836 (40); he had had several 
samples assayed with highly satisfactory results, but believing that 
any gold-mine was a perquisite of the Crown (gold being a royal 
metal), he did not prosecute his investigations further till 1843; in 
the meantime he had informed Mr. Dean that gold and silver did 
occur in the county (37). Mr. O’Neill is supposed by some to have 
discovered gold at Cae Mawr in 1886 (40). ‘The fourth claimant to 
the honour was Mr. James Harvey, proprietor of the mines at Cwm- 
heisian, who appears in 1886 to have called in Mr. Dean to report on 
the mines. 

The gold-mining industry of the Dolgelley Belt, and of Merioneth- 
shire generally, may be said to have commenced in the year 1844. 
The first effort to raise capital to work the gold-mine was made in 
1846, but the idea of profitable gold-mining in Wales only led to 
ridicule from the investing public. In 1847 the North Wales Silver, 
Lead, Copper, and Gold Mining Company, with a capital of £125,000, 
was floated to work the lodes of Vigra, Clogau, Tyddyn-Gwladys, 
and Dol-y-frwynog; this Company paid most attention to copper, but 
before 1849 the veins at Cwm-heisian had been thoroughly tested for 
gold; 300 tons of ore had been milled, and from the resultant 
102 tons of concentrates 72 pounds of gold had been obtained, worth 
approximately £350 (41). 

Throughout early years the Mines Royal Corporation was a constant 
obstacle to the progress of the gold-mining industry. This Corpora- 
tion, by virtue of letters patent granted in Elizabeth’s reign, claimed 
a monopoly of all gold and silver mines in the Principality. After 
a great amount of litigation a compromise was finally effected, and 
the Mines Royal Corporation accepted a royalty, which amounted to 
5 per cent. of the gross output in the case of private lands and 
10 per cent. in the case of Crown lands. 

Stimulated no doubt by the gold discoveries of California and 
Australia, Wales in 1853 experienced a boom of the usual description, 
gold being reported from any and every part of the country. The 
mines worked during this period were mostly in the upper reaches of 
the Afon Mawddach, near to the old mines of Cwm-heisian and 
Tyddyn-Gwladys. Gold was found at this period in an old dump at 
the Vigra Mine by Messrs. Parry & Goodman, of Dolgelley (42), and 
also at the Prince of Wales Mine on the north side of the Mawddach 
estuary, immediately opposite the Penmaenpool railway station. In 


A. R. Andrew—The Dolgelley Gold-belt. 203 


PEN RHOS 
VIGRA 
= coca 
CAMLAN 
GE cREENSTONE 
F F FAULT 

es aa LODE 
SCALE 


XO mites 2s. 1 SQ ce: 


MAP OF 
DOLGELLEY 
GOLD-BELT 


2 Meapwours 


204 A. R. Andrew—The Doilgelley Gold-beilt. 


1854 Clogau yielded its first gold from a single piece of stone worth 
£25; in 1856 a hundred pounds of picked quartz from Clogau yielded 
143 ounces of gold (43). In 1860 extensive and valuable finds were 
made at the St. David’s Mine on the Clogau Hill, revealing the extra- 
ordinary richness of some of the pockets of this mine; on one day, for 
instance, 15 cwt. of quartz was mined which yielded between £500 
and £600 of gold. Im the first half of 1861, 983 ounces of gold, 
worth £3664, were obtained from the St. David’s lode. In 1862 gold 
was met with in the Berth-lwyd Mine, near Tynygroes. In 1863 
gold was discovered at the Ganllwyd, Tyddyn-Gwladys, Glasdir, Moel- 
offryn, Prince of Wales, Cae-mawr, Cambrian, and Garth-gell Mines, 
while active operations were in progress at the Cwm-heisian, Dol-y- 
frwynog, Cefn Coch, and Clogau Mines. The year 1864 witnessed the 
discovery of gold at the Gwyn-fynydd Mine, and in 1867 the Clogau 
Mine paid £22,575 in dividends. 

Several tables have been published at various times showing the 
gold production of the Mawddach district from 1844 to 1866; these 
show considerable discrepancies. I produce here the one which is 
probably the most correct one; it is derived from official sources (45) ; 
the tables which I have omitted are to be found in the works of 
Phillips (46) and Dr. Ure (40, p. 698). 


Gold Production of the Mawvddach River District up to 1865. 


Ore. Goup. 
Tons. Cwt. Qrs. Oz. Dwt. Grs. 

Cambrian . : : : ; . 5K) © @ a @ il 
Castell-carn-dochan . . : ; a Ge Oo) 888) 00 
Cefn-deuddwr . 3 : : ‘ 3 Ol» RORETAO dO. @ 
Clogau (before 1860) . : : : > 30 O nO A) Oo 
Clogau (after 1860). : ; 5 SF ee ey lay ay ey NS 
Cwm-heisian . 6 ; : é ; 00 Om) sh OG 
Dol-y-frwynog : : : 5 6 : ela | dl ee If Bs 
Gwyn-fynydd > ; : é é On laa mh) 1) 
Mawddach River : : : Le RO 2y OO 
Prince of Wales (Hatod-y -morfa) 6 yO G 63) 0nnO 
Welsh Gold Mining Company (Cefn Coch) . See C02) SS a eS 

Wowell 2 i902) Sl) LS | slokGs CmelOmmas 


From 1866 to 1888 gold-mining in Merionethshire was practically 
stagnant, the Vigra and Clogau and the Gwyn-fynydd Mines being 
worked at intervals, the others not at all. In 1888 rich patches were 
struck in the Gwyn-fynydd Mine, and this mine has been worked 
almost continuously since then. For two years it did very well and 
produced over £38,000 worth of gold; then, encountering a bad year, 
it was forced to suspend operations, and the Company controlling it 
was succeeded by another Company which struck rich patches and 
made handsome profits. Since then the gold return from Merioneth- 
shire, practically all from this Dolgelley_ Gold-belt, has always been 
considerable, though it has been derived almost entirely from one or 


A. R. Andrew—The Dolgelley Gold-belt. 205 


other or both of the two mines, the Vigra and Clogau and the Gwyn- 
fynydd. J. M. Maclaren, speaking of the years 1900 and 1901 (88, 
p. 447), said: ‘‘The net profits of the St. David’s Gold and Copper 
Mines, Ltd. (the former Vigra and Clogau), for the year 1900 were 
£39,729, which admitted of the payments of dividends of 60 per cent. 
on the capital. While the gross receipts for that year were £51,544, 
the total expenses were only £8423, or 8s. 7$d. per ton. The royalties 
paid to the Crown were £2088, at the rate of 2s. 1d. per ton of ore 
erushed.”’ In 1903 the St. David’s Gold Mining Company controlled 
practically all the gold-mines of the district ; work was actively 
pushed forward in the St. David’s and Clogau Mine and in the Gwyn- 
tynydd Mine, and good results were obtained. This Company also did 
a great amount of development work at the Voel Mine—an amalgamation 
of the old Prince of Wales, Princess Alice, Moel Ispri, and Cambrian 
Mines. A large and well-designed mill was erected, principally for 
saving lead and zine, but it did very little work. 

A table is inserted on p. 206 showing the total production of gold and 
gold-ore in Merionethshire from 1861 to the present date, and at the 
same time showing the collective output of the St. David’s (Clogau) 
and the Gwyn-fynydd Mines, the principal mines of the district. 


Note.—The table is compiled from that given by J. M. Maclaren, 
and also from the Mineral Statistics of the United Kingdom for the 
years 1861 to 1896; from the Inspectors of Mines, Reports, 1880 to 
1893; from the Mineral Industry of the United Kingdom, 1894 to 
1896; from Mines and Quarries for 1896 to 1907. ‘‘ Estimated 
value” of the ore at the mine as furnished to the Mines Depart- 
ment of the Home Office merely means the estimated profit that 
should accrue from the treatment of the ore, the estimated expenses of 
the year having been deducted. From 1865 to 1874, and also in 1877, 
1883, and 1885, the value (actual) of the gold has been calculated 
from the weight, taking the value of the gold as £38 17s. per ounce. 
For the years 1905 to 1907 the value has been calculated from that of 
the total gold output of Wales. 


Tur Lopes oF tHE DoLGELLEY GOLD-BELT. 


Practically all the auriferous veins of the Dolgelley Gold-belt have 
been worked to a certain extent; on many, operations have never 
proceeded beyond the prospecting stage ; on others a very considerable 
amount of work has been done in opening up and developing the ore 
body. An account will now be given of the various lodes of the belt, 
commencing in the neighbourhood of Barmouth, and running thence 
eastward and northward. 

Panorama Copper Lodes, Barmouth.—Vhese are situated just above 
the main road from Barmouth to Dolgelley, and about 2 miles from 
_ the former place. There are numerous lodes on the property, of which 
four are prominent— 

1. The gold lode, striking 30° east of north and usually nearly 
vertical ; a few hand-specimens of gold were found here about 1860. 
In places this lode is well mineralized, chiefly with galena and also 


206 A. R. Andrew—The Dolgelley Gold-belt. 


Gold Production of Merionethshire. 


GoLD. 
- EstTIMATED AcTUAL 
Yuar. | GoLp-one. Merioneth, | St- David’s,| Vatue. VALUE.. 
etc. 
Tons. Ounces. | Ounces. £ £ 
US Glee 2886 2886 — 10,817 
1862. % “804 5299 | 5299 — 20,391 
USGoam seer 386 553 527 — 1747 
1864 . . 2336 2887 2337 —- 9991 
L8Gd).. 4281 1665 542 _— 6408 
WEVA 4 6 2928 743 214 — 2859 
USGizece 3241 1320 1520 — 5853 
USGSe «ire 1191 436 436 — 1678 
KS69e es — = — == == 
RSaOie oo — 191 191 — 735 
SMe ae — — == = pre: 
US72"  % — — = — = 
NSB a9 4 = = a == == 
STS ws —_— 383 383 — 1477 
UGH) Bo —- 548 548 — 2106 
US 7Gyee — 289 289 — 1119 
SH eet — 139 139 629 536 
WSS 1S — 698 698 — 2825 
W779 os 22 447 447 — 1790 
US SOlen t a 5 5 — 19 
1881 . . — — — — = 
GS 2 uae — 226 226 — 863 
HHS) 6G 869 66 66 100 254 
1SS84i —— — zeae as = 
USSoMe i. 35 3 3 i 13 
1886. . —_— — = — = 
SS) oes ve 1 58 58 —- 209 
USSSae. - 3844 8745 8745 27,300 29,982 
1889 9%.) * 6226 3890 3864 10,746 WS 707/ 
1890 = 575 206 203 434 675 
eote 14,067 4002 4001 12,200 13,700 
BOQ ier a 9990 2835 28385 9168 10,511 
WSO. oo 4489 2309 2299 7657 8619 
1894. . _ 66038 4235 4020 13,573 14,811 
895i 13,266 6600 6502 16,584 18,528 
VS96" 2 OX 2765 1353 1208 4257 5033 
USOT ea. 4517 2032 17388 6282 7185 
US98 2.4 2 7038 395 241 1158 1299 
L899) eas 3047 8327 3208 10,170 12,086 
1900) 2). 20,802 14,004 13,790 49, 925 . 52,147 
1901: . > 16,374 6225 6159 13,920 22.042 
L902. : 29,953 4181 4133 12,621 14,570 
(903°. 28,600 5495 5464 16,995 19,308 
1904. . 23,303 19,653 19,653 68,576 73,925 
UGG ks 15,540 5738 5738 17,600 21,006 
Ce Be 17,025 1838 1811 §238 6453 
LOOP. 22 12,956 1908 1887 5615 6218 
Total . 250,739 117,913 114,308 808,755 423,065 


(incomplete) . (since 1887) 


A. R. Andrew—The Dolgelley Gold-belt. 207 


with blende and chalcopyrite; the lode may be traced for over 
half a mile. 

2. The north copper lode, parallel to the above and vertical; 
it varies in width from 2 inches to 2 feet, and there seems to be no 
system in its thickening and thinning. Like most of the Welsh gold 
lodes, its walls are ill-defined ; it may be traced at intervals for about 
1 mile. The quartz of this lode carries a great deal of chalcopyrite. 
Besides the weathering products of the copper pyrites, the only 
other mineral present is pyrrhotite, and that in small quantity only. 
There is a north and south lode, which intersects this lode, and to the 
west of the junction the main lode becomes much thinner, but much 
richer in copper. 

3. The middle lode is south of the previous one; it strikes 40° 
east of north, is again practically vertical, and may be traced for half 
amile. This lode is opened up at two levels: in the upper, good 
copper ore is found in the neighbourhood of a north and south cross- 
course ; in the lower level (180 feet below) the lode is poorly defined 
and carries no copper values. 

4. The north-and-south lode, which is not worked, is poorly 
mineralized ; there is only a very small amount of galena, blende, and 
chalcopyrite. The lode is of importance only on account of the effect 
it appears to have on the copper values in the north copper lode. It 
dips strongly towards the west at an angle of about 45°. 

All these lodes are found in the Vigra Beds of the Maentwrog. 

Cae-Gwian Lode.—This is a poorly defined and little developed lode, 
about 2 miles up the stream which flows into the estuary at Pont 
Glandwr. The strike of the lode is about 30° east of north, and the 
dip is 80° towards the west; it may be roughly traced for 14 miles ; 
the width is irregular, averaging about 1 foot. Copper pyrites and 
iron pyrites, with oxides of iron and manganese, are seen in the 
’ outcrops, and are present in very small quantity only. The southern 
end of the lode is seen in the Pen Rhos Beds; going north, the lode 
enters and crosses the Vigra, and finally in the Clogau Beds comes to: 
a termination against the Llynbodlyn fault. 

Farchynys Lodes.—On the edge of the estuary immediately south of 
Farchynys House, there are several outcrops of quartz belonging to. 
three sets of vertical veins, striking 40° east of north; these can be 
traced only a short distance. The lodes are on the average about 
2 feet wide, and are poorly mineralized. A small amount of mining 
work has been done and gold obtained, assays conducted by Readwin 
giving 6 dwt. of gold per ton. This lode lies well up in the Pen Rhos 
Beds of the Maentwrog. 

Buwleh-coch-uchaf Lode.—To the east of the Cae-gwian lode, and on 
the east side of the Llynbodlyn fault, there is a parallel lode striking 
30° east of north; it is only traceable for a distance of 500 yards; its 
width is about 1 foot on the average; copper pyrites and iron pyrites 
are seen in the lode. The lode cuts through the Vigra Beds and skirts 
the edge of a sill of greenstone. 

Hafod-uchaf Copper Lode.—This is probably a continuation of the 
Bwlch-coch-uchaf lode, though no trace of a lode formation can be 
seen in the partially drift-coloured 1000 yards which intervene. The 


208 A. R. Andrew—The Dolgelley Gold-belt. 


strike at Hafod-uchaf is 35° east of north, and the dip is in general 
towards the west at an angle of 80°. The lode branches frequently, 
the separated parts usually dying out in a very short distance. This 
Hafod-uchaf lode exhibits in many parts a banded structure due to 
the alternation and admixture of green shale and quartz. The lode 
is sometimes 7 or 8 feet in width, its average width, however, being 
about 8 or 83 feet; the walls are fairly well defined. The prevailing 
minerals in the lode are quartz, chalcopyrite, and pyrites; no gold 
has been taken from this lode. In places the lode is very well 


F 


7 F 
|eee ie ee ve e/e 


_ ales 
Es] es [ee | Hi 


| GREENSTONE CAMLAN CLOGAU VIGRA PEN ai FFESTINIOG 


t FAULT Wikis HIRGWM STREAM 
a ue 


SCALE 


Geological Map of the St. David’s section of the Dolgelley Gold-belt. 


mineralized, but the average tenor of the ore is so much impoverished 
by long stretches of barren quartz that the lode has not paid working 
expenses. This lode cuts through the Gamlan Shales, and is intimately 
associated with an intrusion of greenstone which it intersects at 
several places. 

Hendre-forion Lode.—Half a mile to the east of the Hafod-uchaf 
lode, i.e. a little to the north of the Hendre-forion Farm in the 
Hirgwm Valley, there is another parallel lode striking 30° east of 
nor th, which can be traced for half a mile; the dip is slightly towards 


A, R. Andrew—The Dolgelley Gold-belt. 209 


the west. The lode ranges up to 6 feet in width, averaging about 
13 feet throughout its traceable length. The quartz is poorly 
mineralized, containing occasional pyrites only. The lode occurs 
in the Gamlan Shales, and runs along and across numerous greenstone 
intrusions; it occupies a fault plane which can be traced for several 
miles north and south. 

West Vigra or Nant-goch Lode.—On the west side of the Vigra 
Mountain there are several abandoned copper workings close to the 
Nant-goch Farm. The lode worked can be traced for about 13 miles 
over the shoulder of Y Vigra to the Hirgwm stream, and perhaps for 
half a mile beyond, its strike being 35° east of north. The part on the 
west flanks of Y Vigra used to be called the Nant-goch lode; that on 
the north flanks the West Vigra lode. The lode is vertical; in width 
it varies from a few inches up to 20 feet. Besides quartz the lode 
contains abundant chalcopyrite, pyrites, and pyrrhotite, with a little 
galena ; the latter becomes the most common mineral where the lode 
erosses the shoulder of the Vigra spur. Assays of this lode in 1861 by 
Readwin (34) gave 13 grains of gold per ton. In the south the lode 
traverses the Pen Rhos Slates; towards the north it traverses the 
Vigra and Clogau Beds, and finally dies out in the Gamlan Shales. 
The lode as a rule runs along the junction of the sedimentary rocks 
and the many greenstone intrusions which occur along its course. 

Vigra Lodes—The Vigra Mine worked on two intersecting quartz 
lodes, which formed a conspicuous outcrop of white quartz high on 
the flanks of Y Vigra. One of the lodes strikes almost due east and 
west, dipping to the south at an angle of 70°. It can be traced for 
a distance of 300 yards only to the west of the workings, and here it 
has been worked to some considerable extent. In width it varies 
from 4 to 6 feet; the lode material is of clear white quartz, carrying 
in places chalcopyrite. The second of the lodes is more important ; 
at the Vigra Mine its strike is 60° east of north, dipping 75° to the 
north; to the west it can be traced for a distance of 1000 yards; to 
the east it can be traced into the continuation of the St. David’s lode. 
At the Vigra workings this principal lode system consists of two 
parallel veins about 30 yards apart, connected with each other by 
a series of leaders and cross-veins. Both these veins are irregular in 
width, swelling out to 6 feet and then pinching in to a few inches. 
A low-level cross-cut was driven to intersect the lode at a depth of 
about 400 feet below the upper workings, but was not successful in 
picking up the lode at that depth. The lode matter is quartz 
impregnated with copper pyrites; enclosed in the lode are blocks of 
black shale impregnated with chalcopyrite, bornite, erubescite, arseno- 
pyrite, and to a small extent gold; in some parts the lode contains 
rhodonite ; the mine waters are acid and carry copper in solution. 
At the Vigra workings where the lode is best developed, it crosses the 
Vigra Beds of the Maentwrog; to the west it crosses the Pen Rhos 
Beds, while to the east it enters the Clogau Beds. Where the lode is 
most prominent it is accompanied by intrusive greenstones. 

Clogau_ and St. David’s Lode.—This and the Gwyn-fynydd lode, 
which will be mentioned later, are the principal lodes of the Dolgelley 
Gold-belt. The easterly continuation of the main Vigra lode, known 

DECADE V.—VOL. VII.—NO. v. 14 


210 A. R. Andrew—The Doilgelley Gold-belt. 


as the Clogau and St. David’s lode, runs up over the shoulder of the 
Clogau Hill and down the other side to the Afon Cwm-Mynach. 
Near the top of the hill it is cut across by the north and south 
Bryntirion fault, which moves the eastern end 100 yards to the north. 
This eastern end has been known as the St. David’s lode, the western 
end as the Clogau. After it passes over the Clogau Hill the lode 
becomes thinner and poorer, and little work has been done on it. 
The lode continues, however, as the Cae-mab-seifion lode. On the 
slopes of Clogau the lode has been worked for a distance of about 
1 mile; the combined outcrops of the continuous Vigra, Clogau, 
St. David’s, and Cae-mab-seifion lodes may be traced for about 34 miles, 
the longest known line of outcrop in the Dolgelley Gold-belt. 

The strike of the Clogau lode is 35° east of north, the dip being 
vertical with slight oscillations to either side. For a great distance 
the lode lies among the Clogau black slates,to which it runs parallel 
in strike though not in dip; throughout its whole length in the 
Clogau Beds it is intimately associated with the Llech-fraith green- 
stone sill. The walls of the lode very often show slickensides, and 
are in most places separated from the vein-stuff by more or less 
distinct clayey selvages. To the north-east the lode leaves the 
Clogau Beds and traverses the Gamlan Shales, where it is associated 
with very few greenstones. 

The lode, or rather lode system, branches into parallel veins connected 
by cross-veins and stringers; thus there are three lodes in the St. Dayid’s 
Mine—the north, the main, and the south; to the south-west they 
unite to form one lode with frequent stringers and offshoots. These 
individual lodes vary greatly in width, ranging from 20 feet down to 
streaks, inches only in thickness. 

Fragments of the wall rock frequently appear in the vein-stuff of 
the lodes, and these black, often taleose fragments of shale may at 
times give a brecciated appearance to the vein. The vein often has 
a banded structure, due to stringers or bands of slate or greenstone, 
separated from each other by bands of white quartz; drusy cavities 
are common. In addition to the white quartz and calcite which 
carries little besides pyrites and pyrrhotite, there is also a dark 
quartz, discoloured by inclusions of minerals and particles of the 
country rock. Pyrites, pyrrhotite, chalcopyrite, galena, blende, arseno- 
pyrite, tetradymite, and gold occur, chiefly in the darker quartz; of 
these, gold and chalcopyrite are the only ones that occur in abundance. 

During the years of which full returns have been published 
(1861-1907), these lodes have returned 77,501 ounces of gold from 
145,080 tons of quartz. Analyses of gold from the Clogau lodes gave 
the following results (27) :— 


Gold. Silver. Quartz. Tron. Copper. Loss. Total. S.G. 
(1):90°16. ..) 9°26... °B2 4. tiace. .. ‘trace. |. +26), 10000 RR aliaee 
(2) 089283 ys 924s aco eace —... 19. |:, ,100:00 ae lore? 


The gold is very variable in its distribution, the rich patches being 
found in a most unevenly scattered system of pockets. Some of the 
pockets are very rich; in one case 130 ounces of mixed quartz and 
gold, broken from the lode, were melted down direct, giving 116 ounces 
of retorted gold. The pockets are, as a rule, found in the bands of 


FER. Cowper Reed— Fossils from Dufton Shales. 211 


dark bluish quartz, not in the white quartz. They are frequently 
associated with the included fragments of the Clogau Slates; and 
erystals of gold, along with other minerals, may be seen adhering 
to the slaty surface. The occurrence of tetradymite is regarded by 
the miners as a favourable indication for gold. 

It is certain that the wall rock has some effect on the distribution 
of the gold, for so far not a single pocket has been found where the lode 
has entered into the Gamlan Shales. : 

In the grits and greywackes of the Barmouth Series, immediately 
to the north of the lode, many fractures or cross-courses may be seen, 
which run straight towards the lode and intersect it. It is most 
probable, indeed, that these fractures are responsible, in part at any 
rate, for the distribution of the pockets, as they afford an easy channel 
for the passage of mineral solutions containing gold or some precipitant 
of gold. In many cases, the shoots of gold run more or less trans- 
versely across the lode; a system of cross-courses certainly favours 
such a distribution. In 1875 (40, p. 695) it was noticed that the lode 
was very rich behind one of these cross-courses. The possible 
importance of these cross-courses on the distribution of the pockets 
in the mine has not, however, been recognized, as no systematic 
attempt seems to have been made to follow the cross-courses in the 
search for the rich pockets. 


(To be continued in our next Number.) 


III.—Sxrpewick Museum Norns. 
New Fosstts From tHE Durron SHaEs. 
By F. R. Cowrzr Rezp, M.A., F.G.S. 
Part I. 

(PLATE XVI.) 


SMALL collection of fossils was made a few years ago by 
if Mr. V. M. Turnbull from a cutting: on the Alston Road, near 
Melmerby, and the author’ has already described a new species of 
Lichas (L. melmerbiensis) which was included amongst them. Several 
more new species of trilobites and other groups are now described, 
and the complete list of the fauna is as follows ? :— 


TRILOBITA. OsTRACODA. 
Phacops apiculatus, Salt.* Beyrichia (Tetradella) Turnbulli, sp.nov. 
Calymene senaria (Salt., non auctt.). B. (Ctenobolbina?) superciliata, sp. nov. 
C. Caractaci, Salt. B. (Ceratopsis) duftonensis, sp. nov.* 
Trinucleus Nicholsoni, sp. nov.* Turrilepas sp. 
Acidaspis semievoluta, sp. nov. 
Lichas melmerbiensis, Reed.* Mo.tusca. 
Tornquistia Nicholsoni, Reed. Cyrtolites aff. ornatus, Cour. 
Homalonotus bisulcatus, Salt. (?). Bellerophon (Sinuites) sp. 
Homalonotus ct. Edgelli, Salt. B. (Oxydiseus) acutus, Sow. (?). 
Hi. ascriptus, sp. nov. Cyclonema aft. crebristria, McCoy. 
Iilenus Bowmani, Salt. (?). Holopea sp. 


1 Reed, Grou. Mac., 1907, Dec. V, Vol. IV, pp. 396-400, Pl. XVII. 

? For other lists of fossils from the Dufton Shales, see Harkness, Q.J.G.S., 1865, 
vol. xxi, p. 248; Harkness & Nicholson, ibid., 1877, vol. xxxili, pp. 462-3; 
Marr & Nicholson, ibid., 1891, vol. xlvii, pp. 505, 511. 


212 F. R. Cowper Reed—Fossils from Dufton Shales. 


Pleurotomaria (?) sp. Siphonotreta scotica, Dav. (?). 
Trochoneme sp. Orthis unguis, Sow.* 
Tentaculites sp. O. testudinaria, Dalm.* 
Conularia aff. plicata, Slater. O. Actonie, Sow. 

Ctenodonta (?) sp. O. duftonensis, sp. nov. 
Pterinea (?) sp. O. melmerbiensis, sp. Nov. 


O. turgida, McCoy (?). 


Bryozoa. 
ras 3 , . (Scenidium ? vivocalis, Sp. , 
Crisinella Wimani, sp. nov. Gea oe ts, Sp. NOV 
Monstnypa\t) sp Leptena rhomboidalis (Wilck.). 
BRACHIOPODA. 


INCERT SEDIS. 


Lingula tenuigranulata, McCoy.* Pasceolus sp 


Lingula sp. 
Orbiculoidea perrugata, McCoy. CRINOIDEA. 

O. oblongata, Portl.* Stem joints (round and pentagonal). 
Acrotreta Nicholsoni, Dav. (?). 


The species marked thus * are most abundant. 


TRILOBITA. 
TrinuctEus NicHonsoni, sp. nov. Pl. XVI, Figs. 1-9. 


Head-shield rather more than a semicircle, widest across middle, 
somewhat contracted at base; posterior margin inclined to lateral 
margin on each side at 75°-80°; fringe sloping downwards but not 
steeply inclined, slightly produced backwards at genal angles which 
are furnished with long spines. Glabella pyriform, much elevated 
and swollen, most so anteriorly, gradually decreasing in width and 
height posteriorly to occipital ring without forming neck; front end 
projects slightly beyond cheeks to fringe or overhangs the inner row 
of pits; small median tubercle present on surface of glabella, and on 
each side near its base are two pairs of small deep pits in axial 
furrows, the posterior pair in occipital furrow. Occipital ring narrow, 
nearly as elevated as glabella, separated off by shallow furrow, and 
furnished posteriorly with a short stout spine directed backwards and 
upwards at an angle to the general plane of head-shield and about 
one-third the length of the glabella. Cheeks forming spherical 
triangles, longer than wide, less swollen and elevated than glabella, 
highest along axial furrows, with posterior outer angle rounded, and 
minute granulation over whole surface. Fringe inclined, sloping 
downwards and widening to genal angles which are provided with 
long tapering genal spines curving first slightly inwards and then 
outwards. In anterior part of fringe are four rows of equal-sized 
pits arranged regularly in concentric and radial rows; the pits in 
outermost row are sometimes rather smaller. On the lower surface of 
the fringe the two outermost concentric rows are separated from the 
inner ones by a strong concentric ridge continued back to the genal 
angles and longitudinally along the spines. In front of and at the 
side of the cheeks the fringe widens slightly, and inside the four 
regular rows are introduced one or two shorter concentric rows of 
smaller pits with less distinct radial arrangement, so that 56-6 rows 
with a few smaller irregularly developed pits can be detected at the 
posterior outer angles of cheeks rounding them off. In some specimens 
the pits near the genal angles tend to be alternate. The true genal 
angle (i.e. the base of the spines where the pitted fringe ends) is level 


F. R. Cowper Reed—Fossils from Dufton Shales. 213 


with the second or third thoracic segment, and the posterior and lateral 
edges of the head-shield meet here at about 75°-80°. Neck-segment 
behind cheeks narrow, rounded, marked off by distinct but weak 
furrow. Surface of fringe coarsely granulated. 

Thoracic axis about one-sixth the width of thorax, narrow, prominent, 
cylindrical, with pair of deep pits in furrows between the rings inside 
and above axial furrows. Pleurse of usual type, narrow, horizontally 
extended, flat, with strong diagonal furrow running to obliquely 
truncate tip. Inner edge of backwardly produced genal angles of 
fringe overlaps ends of first three pleure. 

Pygidium broadly triangular; axis long, narrow, conical, reaching 
posterior edge, less than one-fifth width of pygidium, composed of 
9-10 rings, of which the first 3-5 are distinct and well separated by 
transverse furrows deepest at sides. Lateral lobes flat, horizontal, 
with traces of 4-6 radiating fine grooves on each side separating the 
flat pleuree and corresponding to axial rings. Margin of pygidium 
bevelled, steeply inclined. 

mm. 
Dimensions. Length of head-shield (without spine) . . - 10-15 
Width of head-shield . 0 , : . 20-25 

Remarks.—The characters and shape of the glabella separate this 
species from 7’ seticornis, for it is not divided into a swollen frontal 
lobe and depressed cylindrical neck, though the more or less inclined 
fringe and position of the concentric ridge on its lower surface and 
median tubercle on the glabella are featuresin common. 7. Bucklandi, 
Barr., as represented in the Girvan district,) has the glabella 
differmg in the same way, and the genal angles are much more 
produced backwards. The shape of the glabella and presence of 
nuchal spine are much hke Z. Bureaui, Oehlert,*? but otherwise the 
head-shield is distinct. In 7. concentricus, Eaton,* it is the glabella, 
not the occipital ring, which is produced backwards into a spine; 
only the outermost row of pits on the fringe is separated off by the 
concentric ridge on the lower surface, and there are no lateral slits 
or pits near the base of the glabella; the radial arrangement of the 
pits on the fringe is not as a rule so well marked in any of the 
American specimens which I have examined, and there is no median 
tubercle on the glabella, though its general shape is very similar. 
The British forms referred by various authors to 7. concentricus vary 
so greatly that probably more than one species, or at any rate several 
distinct varieties, have been included. Amongst the varieties recognized 
by Salter, Z. favus’ bears some resemblance to 7. Micholsoni in the 
shape of the glabella with pits at its base and in the presence of 
a nuchal spine, but the fringe has different characters. 7. fimbriatus, 
Murch.,° does not seem to be closely allied. 

We may draw particular attention to the resemblance of this 


1 Reed, Girvan Trilobites (Paleont. Soc.), 1903, pt. i, p. 10, pl. i, figs. 10-14. 
* Oehlert, Bull. Soc. Géol. France, 1895, vol. xxiii, p. 300, pl. i. 
a 3 er Paleont. N.Y., 1847, vol. i, pp. 249, 255, pl. lxv, figs. 4a-c; pl. Ixvii, 
gs. la-h. 
4 Salter, Mem. Geol. Surv., vol. ii, pt. i, pl. ix, fig. 5; id., Dec. Geol. Surv., 
1853, vol. vul, pl. vii, p. 6. 
° McCoy, Brit. Paleoz. Foss., 1851, p. 146, pl. iE, fig. 16. 


214 F, R. Cowper Reed— Fossils from Dufton Shales. 


species to some of the so-called varieties of Z. concentricus from 
Tyrone which Portlock described as distinct species. The form 
ascribed by B. Smith! to Portlock’s Z. elongatus,* under the designa- 
tion of 7. concentricus var. elongatus, has a nuchal spine similar to 
T. Nicholsont and more elongated cheeks and glabella than in the 
true 7’ concentricus; apparently there is a median tubercle present, 
and there is mention made of ‘‘ incipient furrows”’ at the base of the 
glabella which correspond to the pits in the axial furrows described 
in the Dufton species. But the pits in the fringe at the genal angles 
are more numerous in the Tyrone examples. In the form termed 
Tf. concentricus var. Portlockt by Smith,® it is remarked that the three 
rows of pits in front of the glabella tend to become confluent in 
a radial direction, as rarely in Z: Wicholsont. The Shropshire specimens 
referred to Z. concentricus have the pits of the concentric rows 
arranged alternately, so that the radial arrangement is lost (as in 
examples of this species from Cincinnati), whereas in many of the 
Welsh specimens there is a radial regularity observable. Barrande’s 
T. ornatus (Sternb.)* seems closely allied to our Dufton species in the 
shape of the head-shield, nuchal spine, pits in axial furrows, tubercle 
on glabella, and radial arrangement of the pits on the fringe; but these 
pits are more numerous and smaller. Further investigation will, it is 
believed, establish the specific independence of several British forms. 


EXPLANATION OF PLATE XVI. 


TrinucLeus NicHoLsonl, sp. nov. 


Fic. 1. Head-shield, with portion of thorax attached, showing impression of lower 
_ surface of fringe with concentric ridge and genal spines. x 2. 


», 2. Head-shield, showing ditto. x 2. 

», 3. Head-shield, showing upper surface of fringe, ete. x 23. 

,, 9a. Portion of fringe. x 10 

», 4. Head-shield. x 38. 

wy Oe Ditto. x 25. 

», 6. Impression of upper surface of fringe and cheek. x 2}. 

;, 7. Nearly complete head-shield. x 23. 

>, 7a. Side-view of same, showing nuchal spine. x 2. 

», 8. Head-shield, showing impression of lower surface of fringe. x 2%. 
,, 8a. Side-view of same, showing impression of concentric ridge. x 23. 
a EB Leeann, Se We 


Part II. 
(PLATE XVII.) 


ACIDASPIS SEMIEVoLUTA, sp. nov. Pl. XVII, Figs. 1-3. 


Head-shield semicircular, with middle part projecting behind base 
of cheeks. Glabella moderately convex, oval, widest across middle, 
well defined by strong continuous curved axial furrows; lateral lobes 


1 B. Smith, Proc. Roy. Irish Acad., 1907, vol. xxvi, sect. iB, No: 95h penl22. 
pl. viii, figs. 38, 4. 

® Portlock, Geol. Rep. Londond., p. 263, pl. iB, fig. 7. 

3 B. Smith, op. cit., p. 121, pl. viii, figs. 1, 2. 
_ 4 Barrande, Syst. Silur. Bohéme, vol. i, p. 623, pl. xxix, figs. 1-9; pl. xxx, 
figs. 41-60. 


Geol. Mag.1910. Decade ViVol. VIP aw, 


A.H.Searle del.et lith. ' West, Newman imp. 


Trinucleus from Dufton Shales. 


ae pathiy a 
tay 


— ay 
i 


mr 


r 
Ms | 
P 
i 


F. R. Cowper Reed— Fossils from Dufton Shales. 215 


completely circumscribed, except first pair. Basal lobes large, oval, 
swollen, half the length and one-third the width of the glabella, and 
placed parallel to its longitudinal axis. Middle lateral lobes sub- 
circular, invading sides of axial lobe of glabella. Anterior lateral 
lobes very small, imperfectly separated from anterior lateral angles of 
axial lobe. Axial lobe of glabella sub-cylindrical, rather more than 
one-third the width of glabella at base, expanding again between 
basal and middle lateral lobes and again in front, with anterior lateral 
angles small and overhanging anterior lateral lobes; anterior end of 
glabella sub-truncate. 

Fixed cheek narrow, curved, convex, rounded, increasing slightly 
in width posteriorly, embracing side of glabella back to eye, where it 
has about one-fifth the basal width of the glabella; behind eye 
descends steeply to narrow neck-ring ; posterior lateral wing of fixed 
cheek somewhat flattened, extending horizontally outwards to facial 
suture. Ocular ridge forming very narrow rounded band outside fixed 
cheek, running back to eye. Eyes small, situated very far back, lying 
behind the middle of basal lobes of glabella, and at about two-thirds 
their width from axial furrows. Facial sutures curving steeply back- 
ward to eyes, running almost parallel to axial furrows; behind eyes 
bending out very sharply (nearly at right angles to anterior branch) 
to follow a course nearly parallel to posterior margin of head-shield 
before curving back to cut this margin at a distance from the axial 
furrows nearly equal to width of glabella. 

Occipital segment forming broad flattened band projecting behind 
cheeks, and having a width equal to nearly one-third the length of 
the glabella, narrowing laterally behind basal lobes where it rises into 
a pair of small oval nodules. Occipital furrow strong, straight. 
Neck-segment very narrow. Free-cheek triangular, convex, sloping 
down from eye to concave marginal part, with strong raised narrow 
angulated border, bearing about twelve equidistant recurved short 
spines, successively increasing in length towards genal angle. Whole 
surface of head-shield tuberculated. 

Pygidium (imperfectly known), broadly semicircular, with strongly 
convex prominent short sub-cylindrical axis, one-third the width of 
pygidium and not reaching posterior margin, composed of two distinct 
rings (with traces of a third) of which the first is by far the most 
prominent, and is ornamented with a single row of tubercles. Margin of 
pygidium armed with five pairs of spines, of which the first two 
pairs are small, short, slender, sub-equal, and directed radially out- 
wards (these are somewhat indistinct and uncertain); third pair 
stouter and longer than the rest, nearly as long as pygidium, slightly 
divergent and connected as curved ridges across lateral lobes with 
first axial ring; two posterior and inner pairs of spines sub-parallel, 
slender, sub-equal, and directed backwards. 


Dimensions, Length of head-shield . 
Width of glabella 
Length of glabella : : 
Length of pygidium (without spines) 


wna aos 
SHnoOs 


Remarks,—T wo good head-shields, one free-cheek, and a somewhat 


216 F. R. Cowper Reed— Fossils from Dufton Shales. 


imperfect pygidium form. the material available. The head-shield 
much resembles that of the species termed 4. evoluta, by Tornquist,? 
from the Zeptena limestone, but the pygidium of this form is unknown. 
A new species (undescribed) from the Starfish Bed, Girvan, also 
possesses many points of similarity, both in the head and pygidium. 
The free-cheek is somewhat like that of A. callipareos, Wyv. Thomson.? 


HoMatLonorus ascriprus, sp. nov. Pl. XVII, Figs. 4-8. 


There is an imperfectly known species of Homalonotus occurring 
in the Dufton Shales which differs in certain particulars from 
H. bisulcatus, to which it is allied, and may be separated as a new 
species under the name ascriptus. The glabella is narrower, longer, 
and more cylindrical, the sides are nearly straight and the anterior 
end is more abruptly truncated, resembling in these respects that of 
the small head-shield from Horderley, figured by Salter (Mon. Brit. 
Trilob., pl. x, fig. 10), which he considered might possibly belong to 
HH. Edgelli, a species founded on a pygidium. Close to the base of 
the glabella the axial furrows, which are deep, straight, and not 
sinuous (as they are in #. bisulcatus), diverge a little. ‘The cheeks 
are narrower, more elevated and swollen, especially in the young 
individuals (Figs. 6, 7), than in the last-named species, particularly 
near the eyes, which are placed rather further forward. The 
pre-glabellar portion of the head-shield is narrower, being only 
about one-fourth the length of the head-shield, and is flattened 
and bent upwards, while the anterior margin of it is_ straight. 
The occipital segment and furrow seem developed as in Z/. bisuleatus. 
The anterior branches of the facial sutures run back to the eyes 
almost parallel, and the posterior branches curve out strongly in the 
usual way from the eyes, bending back finally to cut the posterior 
margin at a distance from the axial furrows about equal to the 
whole basal width of the glabella. The free-cheeks are unknown. 
A remarkable feature is that on the larger specimens the whole surface 
of the head-shield is covered with closely set small tubercles, which 
near the anterior lateral angles of the glabella are developed on the 
cheeks into minute erect sharp spinules, and this character alone 
would seem sufficient to separate this species from H. bisulcatus. 

In the smaller specimens referred somewhat doubtfully to this 
species the surface of the shell is not preserved, but the eyes and 
cheeks are more perfect (Figs. 6, 7). 

A small hypostome (Fig. 8) about 3 mm. long, of a sub-quadrate shape, 
may belong to this species; it is nearly parallel-sided and as wide as 
long; the body is rounded, weakly convex, clearly marked off from the 
border, has a pair of long lateral furrows running obliquely back from 
the anterior corners at asmall angle to the sides for about three-fourths 
its length; the border is rounded and somewhat swollen at the sides 
with small obtuse anterior wings; the posterior border is wider, 
marked off by a strong furrow deepened at the ends. 


1 Tornquist, Siljans. Trilobitf. (Sver. Geol. Undersokn., 1884), ser. c, No. 66, 
p. 28, t. i, fig. 54. 
* Reed, Girvan Trilobites, 1904, vol. ii, p. 112, pl. xv, figs. 11, 13. 


FE, R. Cowper Reed—Fossils from Dufton Shales. 217 


Dimensions. Length of head-shield : : 6 
Length of glabella + occipitalrme . 13 
Width of glabella at base . : > & 
Width of glabella at front end . etd 
Width of head-shield between eyes . 14 : 
Width of head-shield at base. _ zamilt 


cooocono:: 


OSTRACODA. 
Bryricuia (CERATOPSIS) DUFLONENSIS, sp. nov. Pl. XVII, Figs. 9-11la. 


Carapace semi-ellipitical, slightly oblique, rather elongate, widening 
a little posteriorly ; anterior end somewhat pointed ; posterior end wider 
and obliquely truncate above or rounded. Hinge-line straight, as long as 
carapace. Valves moderately convex, crossed by three swollen rounded 
lobes united below by sharp narrow sub-marginal ridge elevated into 
a thin rib on its crest running along middle of anterior lobe, then concen- 
trically with ventral margin, then up posterior lobe, bending obliquely 
forward to ascend to summit of the upstanding process of this lobe. 
Anterior lobe with a width about one-third the length of valve, 
narrowing slightly below, more or less swollen and rounded; first sulcus 
rather obliquely inclined backwards, traversing three-fourths the width 
of the shell; middle lobe narrow, prominent, straight, vertical, nearly 
reaching marginal furrow below; second sulcus straighter and more 
vertical than first sulcus ; accessory lobe represented by small node or 
tubercle almost isolated, situated about half-way down posterior lobe and 
separated from it by strong oblique sulcus, which is continued back- 
wards to about middle of posterior margin, expanding somewhat and 
dividing the posterior lobe into two unequal parts, of which the lower 
forms a small elongated elliptical lobe, obliquely directed upwards 
and forwards with the accessory lobe at its upper end; the upper 
portion of the posterior lobe is strongly elevated, rising nearly at 
right angles to valve, and projecting a little above hinge-line as 
a blunt sub-conical process with flattened posterior face, and with its 
lower edge sharpened by the continuation of the sub-marginal crest, and 
beaded or fimbriated. Border flattened, set at right angles to plane 
of valves, with median narrow raised rim ornamented with a row of 
closely placed small tubercles. Surface of valves smooth. 


mm, 
_ Dimensions. Length . : 2-75-3°0 
Width . eo 2.0 


ftemarks.—The relations. of this species are wide. The raised 
process on the posterior lobe closely resembles that of B. ( Cer.) 
oculifera, Hall,’ but the border of the valves is different. The crest 
on the lobes recalls the sub-genus Steusloffia,” and similar crests are 
present in Strepula,? but they have no genetic significance. . With 
B. ( Cer.) Chambersi, Miller,‘ our species agrees in the reduction or 


1 Jones, Q.J.G.S., 1890, vol. xlvi, p. 21, pl. iv, figs. 19, 20; Ulrich, Proc. 
U.S. Nat. Mus., 1908, vol. xxxv, p. 308, pl. xxxix, figs. 19, 20. 

® Ulrich, op. cit., p. 295, pl. xxxviii, figs. 1-5. 

° Jones, Ann. Mag. Nat. Hist., 1885, ser. v, vol. xvii, p. 403. 

“ Miller, Cincinnati Quart. Journ. Sci., 1874, vol. i, p. 234, fig: 27. 


218 F. R. Couper Reed— Fossils from Dufton Shales. 


obsolescence of the accessory lobe, and in the division of the posterior 
lobe, but the division is not so complete in B. Chambersi, nor the 
posterior horn so long and pointed and recurved. ‘The complete 
division of the posterior lobe is more like that in the B. tuberculata 
group, but the lobes are connected ventrally. The posterior lobe is 
divided in B. (Cer.) quadrifida, Jones,’ and there is a somewhat 
similarly situated accessory lobe. 


Bryricuia (CreENoBOLBINA ?) SUPERCILIATA, sp. noy. Pl. XVII, 
Figs. 14, 14a. 


Carapace small, semi-elliptical, about twice as long as wide, with 
rounded sub-truncate ends, sub-rectangular cardinal angles and hinge- 
line somewhat shorter than maximum length of carapace ; anterior and 
posterior ends of sub-equal size. Valves rather convex, crossed by 
three lobes of unequal size and development, with a fourth smaller 
accessory one on inner side of posterior lobe; all lobes united below 
and merging into rounded sub-marginal ridge. Anterior, posterior, and 
ventral margins thick, with narrow flange projecting above the 
border and bearing a row of delicate radiating short straight 
spines set at equal distances apart ; border thickened, inclined at right ~ 
angles to plane of valves and widening somewhat posteriorly. Anterior 
lobe on valves broad, somewhat swollen, rounded, in width equal to 
about one-third the length of the valve; first sulcus nearly vertical, 
at right angles to cardinal edge and extending about one-half to two- 
thirds of the distance across valve; second lobe narrower than anterior 
one, sub-median in position, more prominent near dorsal edge, slightly 
curved back ventrally ; second sulcus sub-parallel to first, of sub-equal 
length, a little wider dorsally and slightly curved back ventrally 
below accessory lobe; posterior lobe as large (or nearly so) as anterior 
one, with small accessory tubercular lobe about half-way up its inner 
slope, elongated and nearly vertical and almost circumscribed by 
furrows; accessory furrow short, connected above with second sulcus. 
Surface of valves minutely granulated, and dotted with a few small 
scattered tubercles which are especially numerous and have a roughly 
concentric arrangement near ventral margin; a specially large tubercle 
is situated close to the cardinal edge on each of the three main lobes 
and usually two near the ventral margin; three smaller ones are 
usually present in a vertical line on the middle lobe. 


mm. 
Dimensions. Length ve - about 2°25 
Width a - about 1°50 


Remarks.—This species closely agrees with B. cvliata, Emmons,” but 
the presence of the small accessory lobe, the narrower posterior lobe, 
and the situation of the spines on the flange instead of along the edge 
of the valves sufficiently distinguish it. In the B. ( Cz.) subcrassa 
section of the genus or sub-genus Céenobolbina there sometimes exists, 
according to Ulrich,’ a similar small accessory lobe. 


1 Jones, Contrib. Micro. Paleont. Canada, 1891, pt. iii, p. 66, pl. xi, figs. 194, d. 
2 Jones, Q.J.G.S., 1890, vol. xlvi, p. 19, ‘Dl. ii, figs. 12-15; pl. iv, figs. 16-18. 
: Ulrich, Proc. U.S. Nat. Mus. a 1908, vol, XXxv, p. 309. 


Geol.Mag.1910. Decade V.,Vol. VIL.P1. XVIL. 


i | 


IB, 22D) 13, 7 


XL 


Web, LUO) 
A.H.Searle del.et lith. West,Newman imp. 


New Crustacea from the Dufton Shales. 


FE. R. Cowper Reed—Fossils from Dufton Shales. 219 


Bryrrcura (T'errapetta) TurRNBULLI, sp. nov. Pl. XVII, 
Figs. 12, 12a, 13, 13a. 


Carapace obliquely semi-elliptical, somewhat elongated with hinge- 
line as long as carapace and anterior end somewhat narrower than 
posterior, which is broadly rounded. Valves moderately convex, 
divided by three unequal sulci into four lobes, all connected ventrally 
with rounded sub-marginal ridge. Anterior lobe largest, more or less 
swollen and pear-shaped, in width equal to quite one-third the length 
of carapace, narrowing ventrally; first suleus longest and widest, 
slightly oblique or curved back below, but starting at right angles to 
cardinal line, extending about two-thirds to three-fourths across the 
valve; middle lobe almost median, narrow, rounded, about one-half 
the width of anterior lobe, at right angles to cardinal edge; second 
suleus sub-parallel to first, slightly oblique, of same strength as first ; 
accessory lobe smallest of all, more or less nodular, not reaching 
cardinal edge, situated on inner side of posterior lobe, and connected 
by depressed narrow neck with sub-marginal ridge ; accessory furrow 
short, weaker than others; posterior lobe rounded, about two-thirds 
the width of anterior lobe or nearly as large. Border of valves with 
horizontally extended rounded convex flange, separated off by deep 
marginal furrow; flange very narrow in front, widening posteriorly, 
crossed by regularly placed faint radial grooves, with fine stric 
on edge, making a minutely fimbriated and denticulated margin. 
Anterior end of valves provided with a few small marginal spines set 
along the edge of border below the flange. Surface of valves 
minutely granulated, with an irregular concentric row of small sub- 
equal tubercles close inside marginal furrow, becoming a double 
row below anterior lobe and at front end; a few larger tubercles 
irregularly distributed on the lobes. 


mm. 
Dimensions. Length  . : : - about 3-00 
Width (across middle) . . about 1°25 


Remarks.— We may compare this species with B. (Zetr.) marchica, 
Krause,’ and B. subguadrans, Ulrich,’ but the lobation, character of 
the flange, and ornamentation of our species do not completely agree 
with either. In B. complicata, Salter,*? the valves are shorter and 
wider, and the lobes are not developed relatively in the same manner ; 
the surface also is smooth (except in the variety decorata), and the 
flange and ornamentation are distinct in character. 


EXPLANATION OF PLATE XVII. 
Fie. 1. Acidaspis semievoluta, sp.nov. Head-shield without free-cheeks. x 4. 


Ditton Giibos ssc Oe 

>, 3 Ditto. Imperfect pygidium. x 4. 

5, 4. Homalonotus ascriptus, sp. nov. Head-shield without free-cheeks. x 25. 

», 4a. Ornamentation of ditto. x 12. 

»» 9. Ditto. Ornamentation of head-shield near anterior lateral angles of 
glabella. x 12. 

>, 6. Ditto. Head-shield of young individual (?) without free-cheeks. x 24. 


i Krause, Zeits. deutsch. geol. Ges., 1889, xli, p. 19, t. ii, figs. 9-11. 
> Ulrich, op. cit., p. 306, pl. xxxix, figs. 1-3. 
* Jones, Ann. Mag. Nat. Hist., 1855, ser. 1, vol. xvi, p- 163, pl. vi, figs. 1-5. 


220 A, WM. Finlayson—Petrology of Huelva, Spain. 


Fic. 7. Homalonotus ascriptus, sp. nov. Head-shield. x 23. 
» 8. Ditto. Hypostome. x 8. 
» 9. Beyrichia (Ceratopsis) duftonensis, sp.nov. Left valve. x 10. 
», 10. Ditto. Right valve. x 10. 
peel) a eDitto, dithonmescalOs 
», lla. Side-view of same. x 10. 
,, 12. Beyrichia (Tetradella) Turnbulli, sp. noy. Left valve. x 10. 
,, 12a. Ditto, ditto. Impression of surface of same. x 10. 
>, 13. Ditto, ditto: x 10: 
,, 13a. Ditto, ditto. Impression of surface of same. x 10. 
», 14. Beyrichia (Ctenobolbina ?) superciliata, sp. nov. Left valve. x10. 
», 14a. Ditto, ditto. Impression of surface of same. x 10. 


(Zo be continued.) 


IV.—Perrrotocy anp Srrucrure or tar Pyriric Fiery or Huvetva, 
Sparn. 


By A. Monerierr Finuayson, M.Sc., F.G.S., 
Assoc. Inst. Min. Met., Assoc. Otago School of Mines. 


(PLATE XVIII.) 
Inrropucrion. 


(J\HE great copper-mining district of Southern Spain and Portugal 

has been studied by several eminent geologists, and the problems 
presented in the geology of the field and of its ore-deposits have given 
rise to conflicting opinions. The three most debated points have been 
the origin of the ore-deposits, the relations of the igneous rocks, and 
the age of the sedimentary formations. The present paper, the field- 
work for which was carried out during the last summer season, deals 
in the main with the two latter points, and the writer takes this 
opportunity of expressing his indebtedness to Professor W. W. Watts 
and to Dr. C. G. Cullis for their advice and suggestions during the 
subsequent petrological studies at the Imperial College of Science and 
Technology, London. 


GENERAL RELATIONS oF THE DisrrRict. 


The copper-belt is situated at the southern end of the Iberian 
meseta, a fractured tableland whose essential rocks are of Paleozoic 
age. The meseta received its present structure with the tectonic 
movements and igneous eruptions of late Carboniferous and Permian 
times, and is one of the old Hercynian fragments, like the Armorican 
Mountains, the Central Plateau of France, the Vosges, and other 
districts of Europe. The axes of folding trend generally east and 
west, and the movements were accompanied by widespread intrusions 
of igneous rocks, and by the formation of many of the most important 
ore-deposits of the peninsula. The Hercynian disturbances were closed 
by extensive fracturing round the present edges of the tableland, 
notably along its south-east border. Thus the valley of the Guadal- 
quivir follows the line of the insinking created at this period. This. 
great fault cuts off the old mass across the strike of the folds, and is 
marked by a well-defined scarp along the edge of the valley between 
Seville and Cordoba. The fault-line appears to pass westward from 
the lower Guadalquivir, along the south coast by Huelva and the 


A. M. Finlayson—Petrology of Huelva, Spain. 221 


mouth of the Guadiana, as far as the neighbourhood of Cape 
St. Vincent.’ 

Throughout Mesozoic times the area was comparatively undisturbed, 
but in the Eocene there commenced the great Tertiary disturbances of 
the Mediterranean zone, which raised the Betic Cordillera (Sierra 
Nevada and Serrania de Ronda) in the south-east and the Pyrenees in 
the north. Thus the structure of the peninsula was completed. The 
Tertiary earth-moyvements were accompanied by much igneous activity 
along the south-east coast, and also in the neighbourhood of Lisbon. 
Ore-deposition was again active during this epoch, but occurred chiefly 
along the Tertiary lines, the southern part of the meseta not being 
affected to any notable extent during these movements. Later Tertiary 
strata occupy detached areas which were basins of deposition in the 
old tableland, as well as much of the eastern and south-eastern 
districts. ‘The insunken Guadalquivir trough, which connected the 
Mediterranean with the Atlantic transgression, has also been filled 
with Tertiary and later strata. Harth-tremors are still frequently 
felt along the old Tertiary lines, notably along the south-east coast 
and in the neighbourhood of Lisbon. The recent earthquakes generally 
also affect the line of weakness along the Guadalquivir Valley, past 
Cordoba, Penaflor, Seville, and Huelva. Such was that which occurred 
on December 25, 1884.2 Our knowledge of the structure of the 
peninsula is chiefly due to the researches of Macpherson, which are 
summarized in his latest paper.® 


OvurtinE or GroLoecy. 


The copper-field, which extends for a distance of 80 miles through 
the province of Huelva into Seville Province on the east and Alemtejo 
(Pertugal) on the west, is composed of a belt of Paleozoic slates, 
fringed to the south by Tertiary and recent deposits, and succeeded 
on the north by pre-Cambrian schists and gneisses, and by less 
metamorphosed Cambrian strata. he Paleozoic rocks strike east and 
west, and have been thrown into a series of east and west folds. 
All the older formations are intruded by belts of igneous rocks which 
follow these same lines of direction, and were contemporaneous with 
the development of the structure of the district. 


METAMORPHIC AND SEDIMENTARY Rocks. 


The rocks which have been mapped as pre-Cambrian are found 
in a belt along the northern boundary of Huelva Province, outside the 
limits of the ore-bearing zone. ‘They are chiefly gneisses, with bands 
of hornblende-schist and of crystalline and metamorphic limestones, 
succeeded by less altered schists and phyllites. Cambrian schists, with 
quartzites and greywackes, lie to the north of and are conformable 


1 E. Suess, Das Antlitz der Erde, English translation, Oxford, 1906, vol. ii, p. 124. 
2 Bol. Com. Map. Geol. Esp., Madrid, 1891, vol. xvii, pp. 241 et seqq. Salvador 
Calderon, ‘‘ Movimientos pliocenicos y post-pliocenicos en el valle del Guadalquivir”’ : 
An. Soc. Esp. Hist. Nat., Madrid, 1893, vol. xxii, p. 5. J. Gonzalo y Tarin, 
‘* Descripcion fisica, geologica, y minera de la provincia de Huelva’”?: Mem. Com. 
Map. Geol. Esp., Madrid, 1886, vol. i, pp. 241-52. 
3 José Macpherson, ‘‘ Ensayo de historia evolutiva de la peninsula iberica’’:; An. 
Soc. Esp. Hist. Nat., 1902, vol. xxx, pp. 123-65. 


222 A. M. Finlauyson—Petrology of Huelva, Spain. 


with the upper members of the crystalline series, and are widely 
developed in the adjoining provinces of Badajoz and Cordoba. A belt 
of undoubted Silurian rocks, unconformable to the Cambrian, also 
occurs in the northern district. In these have been found graptolites, 
including Donograptus Nilsson (Barr.), IL. latus (McCoy), IL. linnei 
(Barr.), and IM. convolutus (Hisinger),’ as well as the so-called nereites,” 
identical with forms found in the French Pyrenees.? 

In the slates of the mining belt to the south, similar nereites were 
found at Santo Domingo Mine in Portugal, at Lagunazo near Tharsis, 
and elsewhere. On this basis, on supposed lithological differences, 
and on the results of the researches of J. F. N. Delgado in Portugal,* 
a large area of the slates of the mineral zone was mapped as Silurian 
by the Spanish Survey. The rocks, however, contain no graptolites 
like those in the north, the lithological differences are insufficient to 
be of any value, and no unconformity can be detected between these 
rocks and the Carboniferous strata which compose the rest of the 
district. Further, since that date, the belief that the so-called nereites 
represent true fossils has been much discounted, and it is noteworthy 
that Delgado now places the nereite-bearing phyllites of Portugal in 
the Devonian.® Finally, the writer obtained a number of well- 
preserved specimens of Posidonomya bechert, the fossil found in 
the rocks of the district which are mapped as Carboniferous, in 
so-called Silurian rocks at the mine of Cabezas del Pasto, in Huelva, 
near the Portuguese border. All the evidence available, therefore, 
tends to show that the rocks throughout the mining district belong 
only to one period. 

These rocks in general are quartz schists, phyllites, and thin- 
bedded slates, with bands of greywacke and quartzite, and, more 
rarely, limestones. A rapid alternation of greywackes and slates is 
frequently seen, as in the west of the province, at La Laja on the 
Guadiana, and in the Tharsis district. The strike of this sedimentary 
series is remarkably uniform throughout the field, approximating to 
W. 15° N. The rocks generally dip, at a varying angle, towards the 
north. They are fossiliferous at several localities round Rio Tinto, 
the slates near the Marismilla dam on the road to Nerva, and also 
adjoining the Bessemer plant, yielding good fossils. The following 
forms have been described by Lucas Mallada*: Goncatites sphericus, 
Posidonomya becheri, P. lateralis, P. gonzaloi, P. edmondia(?), P. con- 
stricta, P. barroisi, and others. Several of these species, including. 


1 Gonzalo y Tarin, loc. cit. sup., vol. i, p. 405. 2 Thid., p. 395. 

3 Ch. Barrois, ‘‘ Sur les ardoises a néreites de Bourg d’Oueil (Hte.-Garonne) ”’ : 
Ann. Soc. Géol. du Nord, 1884, vol. xi, p. 219. 

4 J. F. N. Delgado, ‘‘ Sobre a existencia do terreno siluriano no Baixo Alemtejo”’ : 
Jorn. Sci. Math. Phys. e Nat., Lisbon, 1878, vol. v, pt. ii; and ‘‘ Correspondance 
relative la classification des schistes siluriens 4 néreites découverts dans le sud du 
Portugal’’: ibid., 1880, vol. vii, p. 103. 

5 J. F. N. Delgado, ‘‘ Systeme silurique du Portugal’’: Commission du Service 
Géologique du Portugal, Lisbon, 1908, pp. 10 and 223. J. F. N. Delgado and 
P. Choffat, ‘‘ La carte géologique du Portugal’’: Congrés Géol. Internat., sess. viii, 
1900; Paris, 1901, p. 743. 

6 « Descripcion fisica, geologica, y minera de la provincia de Huelva’’: Mem. 
Com. Map. Geol. Esp., 1886, vol. i, p. 663. 


A. MW. Finlayson— Petrology of Huelva, Spain. 223 


chiefly Posidonomya bechert, were secured by the writer, as already 
mentioned, in slates near the lode of Cabezas del Pasto, in the west 
of the province. As regards the age of these rocks, Joaquin Gonzalo 
y Tarin, in his memoir on Huelva Province quoted above, places them 
in the Culm (Lower Carboniferous), while F. Romer’ and R. Wimmer? 
both held the same view, and this is endorsed in recent work by 
F. Klockmann’ and -by Bruno Wetzig.* On the other hand, 
J. H. Collins states that Fraas and Etheridge both concluded the 
rocks around Rio Tinto to be of Devonian age.? The only rocks, 
however, mapped as Devonian by the Spanish Survey are some local 
occurrences in the provinces of Badajoz and Cordoba, north and west 
of the present district. The bulk of the evidence, therefore, goes to 
support the conclusion that the rocks of the copper-belt of Huelva 
belong to the Culm, although the adjoining rocks in Portugal are now 
regarded by J. F. N. Delgado’ as Devonian. In any case, there is 
nothing to show that they belong to more than one epoch, as has 
previously been emphasized by Klockmann® and by J. H. L. Vogt.® 
A small patch of Triassic limestones at Ayamonte in the south-west of 
the province, and a coastal belt of Tertiary and Quaternary strata, 
complete the geological column in this district. 


Icneous Rocks. 


These form an important series, not only as constituting a defined 
petrographic province, but also in the relation that their natural 
history bears to the origin of the lodes. They are distributed in belts 
parallel to the strike and to the axes of folding of the slates, and may 
be divided, for purposes of description, into three groups—the 
granites, the porphyries, and the basic group. 

1. Granites.—Yhese occur as a series of intrusive bosses in the 
older rocks in the north of the province, and as far south as the 
Concepcion Mine, and Campo Frio, near Rio Tinto, where they are 
intrusive into the Culm slates. On the whole, however, they are not 
developed in the mineral belt itself. They are evidently con- 
temporaneous with the granitic rocks in other parts of the meseta, 
and form a part of the widespread series of plutonic intrusions 
accompanying the Hercynian earth-movements. 


1 «Uber das vorkommen von Culm-schichten mit Posidonomya becheri anf dem 
Sudabhange der Sierra Morena in der Provinz Huelva’: Zeits. deutsch. geol. 
Ges., 1872, vol. xxiv, p. 589. 

2 “ie Kieslagerstitten des sitidlichen Spaniens und Portugals’’: Berg- u.Hiittenm. 
Zeit., 1883, vol. xlii, p. 327. 

* «Ueber das auftreten und die entstehung der siidspanischen Kieslagerstitten ”’ : 
Zeits. prakt. Geol., 1902, vol. x, p. 113. 

4 «« Beitrige zur Kenntniss der Huelvaner Kieslagerstiitten ’’: ibid., 1906, 
VOlexiv, p. L738. 

° J. H. Collins, ‘‘ Geology of the Rio Tinto Mines’’?: Quart. Journ. Geol. Soc., 
1885, vol. xli, p. 246. 

® Lucas Mallada, ‘‘ Explicacion del mapa geologico de Espafia’’?: Mem. Com. 
Map. Geol. Esp., Madrid, 1898, vol. iii, p. 85. 

7 Loe. cit. sup. 

8 Loe. cit. sup. 

° “Das Huelva-Kiesfeld in stid-Spanien und dem angrenzenden Theile yon 
Portugal”: Zeits. prakt. Geol., 1899, vol. vii, p. 241. 


224 A. MW. Finlayson—Petrology of Huelva, Spain. 


Petrologically, the most common type is a hornblende-granite, but 
therocks vary from muscovite- and biotite-granites, through hornblende- 
granite and syenites, to granodiorites. Monzonite and tonalite also 
occur among them, considerable variation being shown in individual 
bosses. ; 

2. Porphyries.—These rocks are very abundant both in the 
northern district of older rocks and in the mineral belt. In the 
former area they generally occur as marginal phases of the more 
deep-seated granite members, and also as later dykes intrusive into 
these. In the mining-field they frequently occur alongside the lodes, 
and owing to their profusion lodes are seldom found at a great 
distance from them. 

The rocks show considerable variety, ranging, like the granitic rocks, 
from acid to intermediate types, with some alkaline phases. The most 
common type. is probably a quartz-porphyry or rhyolite-porphyry, 
which is well developed at Rio Tinto (Pl. XVIII, Fig. 1). This rock 
contains abundant coarse phenocrysts of quartz, often corroded, and 
with inclusions of the felsitic ground-mass. The felspars are chiefly 
orthoclase and albite, but do not occur as phenocrysts in the more 
acid members. Subordinate muscovite and biotite are generally 
represented by chlorite and other alteration products. The ground- 
mass is felsitic or cryptocrystalline, and frequently contains abundant 
coarser grains of quartz. At times micropegmatites of quartz and 
albite occur, and the rocks become granophyric quartz-porphyries. 
With an increase in albite and microcline, quartz-keratophyres occur 
as local phases of the porphyries at Rio Tinto and elsewhere (Pl. XVIII, 
Fig. 2). A coarser-grained eurite, containing orthoclase and quartz, was 
observed near El Cerro, on the raiiway-line from Huelva to Zafra. 
Larger masses, such as occur in the neighbourhood of the Sotiel Mines, 
are typically granite-porphyries. 

In the less acid members quartz phenocrysts disappear, the rocks as 
a rule are coarser, and include orthophyre or trachyte-porphyry, 
syenite-porphyry, and monzonite-porphyry. Such rocks occur north 
of the Tharsis Mine, at Sotiel, and elsewhere. Micrographic inter- 
growths are absent, and green hornblende is sometimes present, while 
the felspars are chiefly oligoclase and andesine. 

As a rule the porphyries are found as sills and sheets, while the 
larger masses form bosses. In all cases, however, like the granites, 
they are disposed in belts parallel to the trend of the older sedimentary 
rocks. Owing partly to intense dynamic metamorphism of later 
date, contact effects are not well marked adjoining them, and 
mineralogical alteration of the slates can seldom be detected. The 
most usual evidences of intrusion are the presence of bands of 
porcellanite along the margins of the porphyries, and the occurrence 
of inclusions of baked slate. 

Since their intrusion this series of rocks has been subjected to 
profound dynamic metamorphism. This is marked by straining and 
granulation of the quartzes, by crushing and complete sericitization of 
the felspars, and by the conversion of the ground-mass into an aggregate 
of quartz and finely divided sericite. Colourless epidote is often 
abundant as an alteration product of the felspars. Micropegmatites 


A. M. Finlayson—Petrology of Huelva, Spain. 225 


show complete sericitization of felspar, leaving the quartz unaltered. 
Included portions of the ground-mass in quartz phenocrysts are also 
commonly preserved from the alteration which has affected the rest 
of the rock. Along the margins of the intrusions dynamic effects are 
particularly marked. Here the porphyries have frequently been 
converted to highly cleaved rocks with a greasy lustre. Under the 
microscope these show the same mineralogical changes as the more 
massive porphyries, carried to a greater extreme, while the effect 
of pressure has resulted in perfect schistosity, marked by folia of 
felted sericite (Fig. 3), which enclose granulated crystals of quartz 
and occasional aggregates of sericite and epidote representing altered 
felspars. As indicating the origin of these foliated types, it is 
significant that they correspond, in the nature of their phenocrysts, in 
each case with the adjoining massive porphyries. The coarser and 
more porphyritic rocks are accompanied by brecciated rather than 
foliated modifications, in which the crystals are arranged in a broken 
confused aggregate, which is, in the hand-specimen, with difficulty 
_ distinguishable from a pyroclastic rock. The absence of foreign 
constituents, however, and the remarkable uniformity of these cleaved 
and crushed types, as well as their microscopic structure and relations 
to the less altered porphyries, indicate that their present structure is 
the result of pressure and movement. 

The age and relations of this series of rocks have been considerably 
discussed. Most of the geologists who have examined them, including 
J. H. Collins,! Gonzalo y Tarin,? L. de Launay,*® and J. H. L. Vogt,* 
have regarded them as intrusive into the slates. The highly cleaved 
marginal phases were considered by Collins to be the result of pressure 
during solidification, by Tarin as effects of contact-metamorphism, and 
by Vogt as due to subsequent pressure and shearing. On the other 
hand, F. Klockmann has maintained, after considerable investigation, 
that the porphyries are subaqueous lava-flows contemporaneous with 
the deposition of the slates, and that the foliated and cleaved rocks 
associated with them are tuffs and ash-beds, which have been 
subsequently sheared.° 

The present writer’s conclusions, after the examination of a large 
series of exposures and of collected specimens from various parts of 
the district, are in agreement with those of Vogt and opposed to 
the views of Klockmann. The chief reasons for concluding that the 
porphyries are intrusive, and that the cleaved varieties are due to 
later pressure and movement, are as follows :— 

(1) The occurrence of micrographic intergrowths and of corroded 


1 «* Geology of the Rio Tinto Mines’’: Q.J.G.S8., 1885, vol. xli, p. 245. 

2 “Descripcion fisica, geologica, y minera de la provincia de Huelva’’: Mem. 
Com. Map. Geol. Esp., Madrid, 1886, vol. i. 

3 <* Mémoire sur |’ industrie du cuivre dans la région d’Huelya’’: Ann. d. Mines, 
1889, ser. virt, vol. xvi, p. 407. 

4 <Das Huelva-Kiesfeld in siid- Spanien und dem angrenzenden Theile yon 
Portugal’’: Zeits. prakt. Geol., 1899, vol. vii, p. 241. 

> F. Klockmann, ‘‘ Uber die lpeesc ee Natur der Kiesvorkommen des stidlichen 
Spaniens und Portugals” : Sitzungsber. d. preuss. Akad. d. Wissensch., Berlin, 
1894, vol. xlvi, p. 1173; and ‘* Ueber das auftreten und die entstehung ‘der siid- 
spanischen Kieslagerstatten”? : Zeits. prakt. Geol., 1902, vol. x, p. 113. 

DECADE V.—VOL. VII.—NO. V. 15 


226 A. M. Finlayson— Petrology of Huelva, Spain. 


quartz: phenocrysts with inclusions of ground-mass indicates hypa- 
byssal. rather than volcanic rocks. 

(2) In a single exposure of porphyry the texture is frequently 
found to vary from coarse to fine in passing from the centre to the 
edge of the mass. 

(3) Intrusion is indicated by poreellanous 1 margins and by the 
presence of inclusions of slate, which have been caught up in the 
porphyries. 

(4) In some cases an examination of the line of contact showed 
that it crossed the bedding of the slates, and that a later cleavage 
had been developed in the slates parallel to this line of contact. 

(5). The occurrence of fine-grained porphyries as marginal phases 
of the granites in places is opposed to the view that they are layva- 
flows, as is also the occurrence of exactly similar porphyries in rocks 
of Silurian and Cambrian age in the north of the province. 

(6) The close correspondence of the cleaved varieties with the 
associated massive porphyries in each case, the great uniformity of 
the cleaved types, and the absence in them of foreign constituents, - 
all go to show that they are not of pyroclastic origin. 

It is therefore concluded that the porphyries are intrusive into 
the slates, and that since their intrusion they have been affected by 
intense pressure, which has given rise to shearing along the lines 
of contact with the slates, which were naturally lines of weakness. 
To this shearing has been due the development of the cleaved and 
foliated varicties of porphyry. If this is the correct interpretation— 
and all the evidence gathered in the present work goes to show 
that it is—then the porphyries must, from their petrological analogy 
to and frequent association with the granitic rocks, belong to the 
same stage of igneous activity as these, but to a less deep-seated 
phase of consolidation. They were therefore intruded along with 
the plutonic masses during the disturbances of the Hercynian epoch. 
At the same time, the intrusions were probably spread over a con- 
siderable interval, as dykes of granophyre and felsite occur in places 
intrusive into the granites. 

8. Basie Intrusions—These have a similar distribution to the 
porphyries, but are less abundant. In the rocks of the mining field 
they occur generally as sills and occasionally as bosses. They 
include diabases, augite-porphyrites, dolerites, and augite-diorites. 
Augite is very abundant and generally ophitic in habit. The rocks 
have, as a rule, a high titanium content, marked by ilmenite, by 
pleochroic augite, and by abundant perovskite. ‘The felspars vary 
from andesine to anorthite, brown hornblende is occasionally present, 
and olivine very rarely. The adjoiing contact-altered slates show 
the development of, first, chlorite, and finally, abundant yellowish- 
brown epidote. 

That this basic group, whose members appear from their generally 
close mineralogical resemblance to be all of the same age, is the 
youngest of the series of igneous rocks in the district, is indicated by 
the fact that they are found in places intrusive into both granites and 
porphyries, while they have been also intruded into the Triassic rocks 
at Ayamonte. Further, they are unaffected by the cleavage and 


A. M. Finlayson—Petrology of Huelva, Spain. 227 


shearing seen in the porphyries, and the epidotization ‘of the adjoining 
slates is subsequent to the sericitization of the slates which accompanied 
the development of cleavage throughout the area. The basic rocks 
must therefore have been intruded towards the end of the series of 
movements which has affected the district, and a considerable time- 
interval has clearly separated them from the older granites and 
porphyries. 7 
STRUCTURE. 

The slates of the area show a very uniform east-and-west strike, 
while the dip is generally to the north at a varying angle. This 
alignment is preserved in the associated igneous rocks. In the absence 
of folding or of overthrusting, there would be a very great thickness 
of rocks to account for between the coastal district and the northern 
metamorphic complex. In the absence of fossiliferous horizons, or of 
strata with a persistent lithological character, the structure of the 
district is difficult to unravel. The observed facts, however, suggest 
the presence of a series of inclined isoclinal folds, which have been 
followed, further, by overthrusting along the limbs of the folds, more 
especially in the neighbourhood of the junctions of porphyry and slate. 
These junctions have clearly in many cases been lines of movement, as 
indicated by the marginal phases of cleaved and brecciated porphyry. 
Further, the lode-zones also invariably occupy lines of structural 
weakness. Thus many lodes occur at the junction of slate and 
porphyry, some at the junction of slate and diabase, and the majority 
are contained in belts of crushed or sheared slate, enclosed between 
more resistent sills of porphyry or bands of greywacke or quartzite. 
The persistent lenticular form of the lodes also indicates that they 
occupy zones of fault-sipping. The shearing and faulting along the 
present lode-zones was, however, distinctly later than the folding 
of the rocks and the development of cleavage in them, since it involves 
the basic intrusions, and since breccias along the lode-walls, cemented 
by ore, are seen to contain fragments of previously cleaved and 
sericitized slate and porphyry. These thrust-movements, which 
preceded the deposition of the ores, were, therefore, the last of the 
series of Hercynian disturbances in the district. sae al 


ConcLUsIONS. 


The general sequence of events in the area during the Hercynian 
epoch of crust-movement appears to have been as follows: -The 
deposition of the Lower Carboniferous strata was succeeded by elevation 
and folding of the rocks, the forces acting along north and south lines, 
probably towards the north. With the inception of pressure came 
intrusions of granitic and porphyritic rocks, varying from acid to 
intermediate, throughout the stressed area. Further pressure after 
these intrusions resulted in cleavage of the slates and considerable 
dynamic alteration of the porphyries, especially along their margins, 
where they offered least resistance. After an interval of rest there 
was a renewal of sub-crustal forces, expressed first by the intrusion of 
basic rocks over the same area, and then by further pressure which 
resulted in shearing and probably overthrusting along zones of 
weakness. The deposition of the ores immediately followed these last 


228 A. M. Finlayson—Petrology of Huelva, Spain. 


movements, the lodes being formed in the zones of sheared or 
shattered rock. 

The district affords a good illustration of Aes features. In the first 

place, the development, by magmatic differentiation, of the series of 
igneous rocks has been closely “connected with the earth-movements 
which have given the area its present structure. The igneous rocks 
and the tectonic structure are coextensive, and the. magmatic 
differentiation has doubtless been attendant on the sub-crustal stresses 
of the Hercynian epoch. In the second place, the relation of the ore- 
deposits to the igneous rocks is, broadly speaking, a genetic one. 
The defined petrographic province, limited to a certain area, is 
accompanied by the equally defined group of pyritic ore-bodies, limited 
to practically the same area. In other words, there is here a 
metallogenetic province accompanied by a corresponding petrographic 
province. The association indicates the close dependence of ore- 
formation on earth-stresses and magmatic processes. While there 
is nothing to show that the lodes are genetically related to one 
particular group of igneous rocks, there is strong reason for believing 
that the concentration of the sulphides has been primarily a magmatic 
process, intimately bound up with the progressive differentiation which 
resulted in the igneous rocks now exposed. ‘The ore-deposits, in 
short, represent the final product of the magmatic processes, just as 
the fault-zones in which the lodes occur were the last result of 
the earth-movements with which these magmatic processes were 
involved. 
' he Huelva copper-field is “closely paralleled in almost every 
respect by the Avoca district in co. Wicklow.! Here a belt of 
Palsozoic slates is succeeded to the west by the Leinster granite 
massif, and the slates are intruded by a series of abundant sills and 
dykes of both acid and basic rocks, in part contemporaneous with and 
in part later than the granite. These intrusions have been intensely 
altered by subsequent pressure and movement,” and, as in the Huelva 
district, there is a general parallelism in the strike of the slates and in 
the alignment of both the granite and the abundant smaller intrusions. 
Finally, there occurs in the slates, and on the same general trend, 
a belt of pyritic lodes, sometimes enclosed in slate and sometimes 
adjoining sills of felsite or greenstone, but always in zones of 
‘shearing and:crushing. Both structurally and mineralogically the 
ore-bodies of Avoca and those of Huelva show exactly the. same 
features. Specimens of ore from the two fields are indistinguishable 
under the microscope. It is clear that in both districts similar 
agencies have been at work, with the production of exactly similar 
results. 


EXPLANATION OF PLATE XVIII. 


Fic. 1. Rhyolite-porphyry, Rio Tinto. The specimen contains quartz phenocrysts 
and abundant smaller grains of quartz, embedded in a felsitic or crypto- 
crystalline matrix, which has been largely converted to ‘sericite. The 
rock is impregnated with pyrite and somewhat sheared. x 36. 


1 Explan. Sheets 138 and 139, Geol. Surv. Ireland, 1888. 
* Sum. Prog. for 1900, Geol. Surv. Great Britain, p. 51. 


Grout. Mac. 1910. Pratt XVIII. 


om ae 

Pre 
ped ae oe * 
a ye 


be eee 


Porphyries, Huelva, Spain: (1) Rio Tinto, (2) Tharsis, (3) Sotiel. 


it i 
uy a 


Dr. H. H. Swinnerton—Organie Remains in Trias, 229 


Fic. 2. Trachyte-porphyry (near keratophyre), Tharsis. Contains phenocrysts of 
orthoclase, albite, and corroded quartz. The ground-mass is a felt of 
very fine felspar laths with abundant coarser quartz grains, x 36. 

Fic. 3. Sheared porphyry, Sotiel. Quartz phenocrysts have been crushed and 
granulated, felspars have been converted to aggregates of sericite fibres, 
and the ground-mass to a very fine felt of quartz and sericite, with 
a highly developed schistosity. x 36. 


_V.—Oreanic Remarns In THE Trtas oF NorrineHam. 
By H. H. Swiynerton, D.Sc,, F.G.S., F.Z.8. 


(T\HE city of Nottingham is built upon the outcrop of the Trias. 

Building and road-making operations consequent upon its rapid 
growth often lead to the laying bare of the underlying Bunter, 
Keuper Waterstones and Marls. Unfortunately the work is usually 
carried on with such rapidity that good exposures are often missed. 
A temporary cessation of activities in one part of the Sherwood 
suburb, however, left a beautiful exposure of the Waterstones. 
A careful examination of this during the past few months has led 
to the discovery of footprints and fish-remains. The footprints are 
of a type which does not seem to fit into the generally used system of 
classification. In 1857 the Rev. A. Irving found a Cheirotheroid 
print in the railway cutting at Colwick. ‘his is the only record of 
the previous discovery of footprints in this district. 

Well-preserved remains of fish (Semzonotus) are fairly common 
in one layer of light-coloured sandstone only 23 inches thick. 
The upper surface of this is partly covered with small, ill-defined 
ripple-marks. The fish seem to have been left stranded upon this, 
and in their struggles to escape have made depressions and become 
buried in the sand they stirred up. The remains are buried in 
lenticular pieces of sandstone which can be lifted bodily out of the 
depressions. These vary in size from a few inches across to a couple 
of feet. The horizon at which they occur is evidently higher than 
that at which similar remains were found by Edward Wilson at 
Colwick in 1879. 

The scales, fin-rays, and some bones are often perfectly preserved, 
but being embedded in sandstone they have to be dissected out with 
great care. As this is a tedious process, it seemed advisable to 
announce the find without delay. | 


REVIEWS. 


——— 


Tue Coat Bastn or CommMeEntrRY IN CENTRAL FRANCE. 


fF\HIS is the title of a paper by Mr. J. J. Stevenson (Ann. New 

York Acad. Sci., xix, p. 161, February, 1910). The basin was 
described in 1887 by Henri Fayol as about 9 kilometres long, 
3 kilometres wide, and 700 metres deep; and it is isolated from 
two other small basins mainly by granite, the basins having been 
separated just prior to the time of the Coal-measures. Thus the 
deposits were always distinct, a conclusion formed by De Launay and 


wok Reviews—Ooal Basin of Central France. 


confirmed by Fayol. The most important contention of Fayol was 
that the coal-seams were formed, not in situ, but by transport; and to 
study this question Mr. Stevenson paid a special visit to examine the 
enormous excavations that have been made in mining the coal by 
stripping. 

The Lower Coal-measures are formed almost wholly of rather coarse 
materials, with some unimportant lenticles of anthracite; the Middle 
Coal-measures consist chiefly of fine materials, and include the great 
coal-beds—mainly a single bed, the Grande Couche, 30 to 60 feet 
thick, but divided into two or more seams in a westerly direction ; 
the Upper Coal-measures comprise more or less coarse detritus, and 
practically contain no coal. 

The strata have a dip of about 30°, and this has been supposed to 
be the original slope of the beds. Fayol conceived that the strata 
were deposited in accordance with their specific gravity, the plant 
debris forming the beds of coal. Mr. Stevenson remarks that when 
one considers the enormous mass of the Grande Couche, not less than 
30,000,000 cubic metres, it is difficult to realize that it could have 
been formed from such vegetable matter as could have been washed in 
from an area of about 26 square miles; and he maintains that the 
form and variations of the Grande Couche leave little room for doubt 
that the bed represents plants which grew where the coal now is. 
The marsh-vegetation consisted of Cordaites trees, with a dense 
growth of ferns, lepidodendra, and other plants; and the sandy 
clay underlying the Grande Couche, crowded with vegetable remains, 
is clayey enough to have prevented downward drainage. 

Evidence is brought forward to show that the strata were exposed 
to tremendous pressure after consolidation. Occasionally the coal 
itself is crushed into small lenticles, which have been rubbed and 
polished. . The author concludes that a differential subsidence, com- 
bined with: the effect of compression and carbonization, would account 
for the high dips, which have been regarded as original. 

Mr. Stevenson promises to publish a monograph on the formation of 
coal-beds. In the present communication he has not considered that 
the quiet, undisturbed condition of the organic remains, both plants 
and animals, so abundant in the coal-shales of Commentry, offered the 
best and most complete refutation of M. Henri Fayol’s theory of the 
transportation and redeposition of the materials of these coal-beds in 
their present resting-place. 

A reference to the great work by M. Chas. Brongniart on the 
wonderful insect fauna of Commentry would show how abundant and 
well preserved are the remains of these delicate and beautiful winged 
organisms.! Whilst in Europe and North America there have been 
described about 120 examples, at Commentry alone, since 1878, 
1300 have been met with, of which the greater part is admirably 
preserved.’ 

After sixteen years of continuous labour, mostly devoted to the 
insect fauna of Commentry, M. Chas. Brongniart brought out his great 
work Histowre des Insectes Fossiles des temps primaires (Ste. Etienne, 


1 See Grou. Mac., 1879, pp. 97-102, Protophasma Dumasii, Ch. Br. 
2 Tbid., 1885, pp. 481-91, Pl. XII, Woodwardia, Caloneura, Corydaloides, ete. 


Reports and Proceedings—Geological Society of London. 231 


1893, 4to, pp. 496; and Atlas, 4to, pp. 44 and plates 53, many of 
which are double or folding). 

‘‘ It has been reserved [says his reviewer’] to one favoured locality 
in a circumscribed area of Central France [Commentry] to furnish 
more specimens of fossil insects and in a better and more complete 
condition than in all the previously known localities of the world put 
together.” It may be of interest to record here that Dr. Brongniart 
discovered at Commentry the largest Dragon-fly known (Meganeura 
Mony1), measuring 28 inches in the spread of its wings. 


IRS OES IyS) eB) FSs54@) Spay Dam tess 


I.—Grotocicat Socrery or Lonpon. 


March 9, 1910.—Professor W. W. Watts, Se.D., M.Se., F.R:S;; 
President, in the Gian 


The Pasta announced that the Council had awarded the Proceeds 
of the Daniel Pidgeon Fund for 1910 to Mr. Robert Boyle, B.Sc., 
who proposes to make a series of researches on the Carboniferous 
Building-stones of Scotland. 

The following communication was read :— 

‘‘The Carboniferous Succession in Gower (Glamorganshire).”” By 
Ernest Edward Leslie Dixon, B.Sc., F.G.S., and Arthur Vaughan, 
Ben, DD). Sey F.G.S. 

The succession in three districts in Gower is described, the districts 
being so situated that a comparison of their respective developments 
can be interpreted in the light of the fact that, during Avonian time, 
the nearest coast lay to the north, with a general east-and-west trend. 
With the description of the lithological sequence are included notes 
on some breccia-like limestones, characteristic of D, and on ‘lagoon- 
phases’ and the origin of radiolarian cherts. To the faunal lists are 
added notes on the D,—D, phase of the Dibunophyllum-zone, which 
distinguishes Gower from the rest of the South-Western Province at 
present known, and on the correlation of that zone with the Upper 
Bernician of Northumberland. From the faunal sequence it is 
concluded that the zones Z, C, 8, D,, and D, (the K Zone is poorly 
exposed) are characterized by the same assemblages as in the 
Bristol area. 

The lithological sequence shows (1) that over the whole area the 
depth of the Carboniferous sea underwent a complete cycle of inter- 
mittent change during Lower Avonian time, the initial deepening 
being followed by gradual shallowing up to the top of the lower part, 
C;, of the Syringothyris-zone, which was deposited almost at sea- 
level; (2) that a similar cycle marked the ensuing period up to the 
top’ of the Seminula-zone ; ; (38) that a similar but “smaller cycle took 
place in the Dibunophyllum-zone, the latter actually reaching the 
surface; and (4) that a fourth cycle, commencing with a far-reaching 
physiographic change, characterized the Posidovomya-zone. 

Further, a comparison of the sequences and thicknesses in the threc 


1 Grou. Mac., 1895, pp. 233-6. 


232 Reports and Proceedings—Geological Society of London. 


districts shows that, not only were the downward movements of the 
sea-bottom during the first two cycles greater in the south than in the 
north, but also that the axis on which the movement during the first 
cycle hinged was different in direction from the axis during the second 
cycle. The bearing of these movements on the question of the 
delimitation of the divisions of the Avonian is then discussed. They 
suggest that the base of the upper part, C., of the Syringothyris-zone 
should form the base of the Upper Avonian. On the other hand, the 
base of C, in at least two localities is closely connected, faunally, 
with the zones below, whereas the fauna of the main mass of C, passes 
into S, without appreciable change other than the introduction of 
Lithostrotion. It will, therefore, in all probability be decided that 
the break between the Lower and the Upper Avonian should be taken 
at a level within C rather than at the base of the Seminula-zone. 
For the present, however, this question must be deferred, since it 
concerns the whole extent of the formation in Belgium, the North of 
France, and the British Isles. 

The paper concludes with notes on some of the corals and Brachiopods, 
including one new species of coral and two new species and a new 
variety of Brachiopod. 


March 23, 1910.—Professor W. W. Watts, Sc.D., M.Sc., F.R.S., 
President, in the Chair. 


The President referred in sympathetic terms to the recent decease, 
at the age of 98, of Prebendary William Henry Egerton, who had 
been a Fellow of the Society since 1882. 

The following communication was read :— 

‘‘On Paleoxyris and other Allied Fossils from the Derbyshire and 
Nottinghamshire Coalfield.” By Lewis Moysey, B.A., M.B., B.C., 
EGS. 

After reviewing the bibliography of Palg@oxyris, the author records 
the finding of twenty-two specimens from Shipley Clay-pit (Derby- 
shire), and over 130 from Digby Clay-pit (Nottinghamshire), also 
several isolated examples from other localities in the district. 

He describes P. helicteroides (Morris), noting especially the presence 
of a ‘beak’, which had not hitherto been adequately described. 
He then describes P. prendeli (Lesquereux) from Shipley Clay-pit, 
again noticing the formation of the ‘beak’. The discovery of 
P. Johnsoni (Kidston) from Digby is noted, and it is proposed that 
this fossil be removed into the genus Vetacapsula. 

The author also describes a specimen of V. Cooper? (Mackie & Crocker) 
from Newthorpe Clay - pit (Nottinghamshire). He discusses the 
differences between this and other specimens, and Mackie’s type- 
specimen, but considers it unadvisable to multiply species. 

A review of the bibliography of Fayolia is followed by the description 
of a new species from Shipley Clay-pit; also a small compressed 
example is described as near to F. dentata (Renault & Zeiller). The 
author then discusses the distribution of these organisms in time, and 
their possible affinities with the egg-capsules of the Cestracionts and 
the Chimeroids. 


Reports and Proceedings—Mineralogical Society. 233 


II.—Mrneratoercat Socrery. 
March 15, 1910.—Professor W. J. Lewis, F.R.S., in the Chair. 


G. W. Grabham: A new form of Petrological Microscope, with notes 
on the illumination of microscopic objects. The new instrument, 
which is of the ‘Dick’ or ‘ English’ pattern, has a focussing sub- 
stage carrying a series of condensers mounted on a triple nose-piece, 
each capable of being inserted in the axis of the instrument. A new 
explanation was given of the ‘ Becke’ or bright-line effect, especially 
applicable to parallel polarized light traversing mineral sections which 
meet along inclined junctions.—W. F. P. McLintock: On Datolite 
from the Lizard District. Datolite, which is associated with calcite, 
chalcopyrite, and natrolite (rare) in veins and geodes at the junction 
of the serpentine and hornblende schist, Pare Bean Cove, Mullion, 
Lizard District, Cornwall, occurs in crystals measuring up to 2cm. 
along the 6 axis, and displayed fourteen forms, of which two were new. 
An analysis gave SiO, 37:45, CaO 84°67, Fe, 0, and Al, O03 0°57, 
B, O, 21°87, H,O 5°67; total 100-23.—Arthur Russell: Additional 
notes on the occurrence of Zoolites in Cornwall and Devon. The 
occurrence of heulandite, a mineral hitherto not recorded from 
Cornwall, at Carrick Du Mine, St. Ives, Cornwall, was described ; 
also of chabazite and heulandite at the Ramsley Mine, South Tawton, 
Devon.—Dr. J. W. Evans: A modification of Stereographic Projection. 
Faces below the plane of projection are represented by the same points 
as parallel faces above it, upper faces being distinguished by a plus 
and lower faces by a minus sign.—Dr. J. W. Evans: Axes of Rotatory 
Symmetry. Coincidence is complete or codirectional when equivalent 
lines and their directions coincide, incomplete or contradirectional 
when equivalent lines coincide, but equivalent directions of uniterminal 
lines are opposed ; in both cases it is colinear. Ifa minimum rotation 


20 . ; : é 5 : ee 
of — result in codirectional, contradirectional, or colinear coincidence, 


the axis of rotation has codirectional, contradirectional, or colinear 
symmetry, with cyclic number x.—Professor H. L. Bowman exhibited 
models illustrating space-lattices and Sohncke’s point-systems. 


CORRESPONDENCE. 


THE USE OF THE TERMS ‘LATERITE’ AND ‘BAUXITE’. 


Srr,—Mr. Scrivenor’s further remarks on this subject in the March 
number of the GroLocicaL Magazine, replying to mine in the number 
for November last, bring into sharp relief some of the difficulties 
which he and others experience with regard to the recognition and use 
of ‘laterite’ as a scientific term. I for one am not unaware of these 
difficulties. Indeed, I perceive one or two which are in my opinion 
more serious than those mentioned by Mr. Scrivenor. At the same 
time, all these difficulties taken together are small compared with 
those which prevent us from adopting the use of the mineralogical 
term ‘bauxite’ as a rock name. Furthermore, surely the fact that 
some engineers—and, alas! some others—have abused the term laterite, 


234 . Correspondence—T, Crook. : 


is not a sound reason why geologists should relinquish their use of it 
in a scientific sense, especially when, as I pointed out in my previous 
letter, such a use can be shown to be quite consistent with the 
original meaning of the term. 

My. Scrivenor now admits the inaccuracy involved in the un- 
restricted use of the term laterite for ferruginous surface products. 
He seems not to be aware, however, that his “proposal to extend the 
use of the term bauxite is equally objectionable. His only remedy 
for the abuse of the word laterite is a still further abuse of the word 
bauxite, a course of procedure in which I confess inability to see any 
wisdom at all, practical or otherwise. Unfortunately, the term 
bauxite has been so carelessly used by most writers, that there is 
some degree of plausibility in his suggestion. 

Now I fully admit that bauxite is a mineralogical uncertainty ; and 
that there may not be a definite mineral corresponding in composition 
to the formula Al, 0,2 H,0O, which has always been attributed to 
bauxite by mineralogists; but until this possible fact has been 
definitely established and accepted by mineralogists, it seems to me 
that bauxite must remain a mineralogical name which cannot be 
applied indiscriminately by scientific workers to lateritic weathering 
products. 

Is Mr. Scrivenor aware of the fact that the use of the term bauxite 
in a petrographical sense, for a mixture of hydrated oxides and other 
substances, would invalidate its use as a simple mineral name? If 
so, dare he assert, in view of the proved existence of xanthosiderite 
(Fe, 0, 2 H, 0), that its aluminium analogue, the bauxite of mineralogy, 
does not exist? If not, what name does he propose to give to the 
possible Al, O, 2 Hy O of mineralogy ? 

If it be il ererabely proved that the mineral bauxite (Al, O, 2 H, O) 
does not exist, and that the material which has hitherto been regarded 
as such is really and always a mixture of gibbsite (Al, O33 H, O) and 
diaspore (Al, O, H, 0), it will then be necessary for GO ly os 9 to 
abandon mete as a simple mineral name; and in that event it will 
possibly be available for petrographical use. If on the other hand, 
as is more likely to be the case, mineralogists decide that there is 
a definite mineral corresponding in composition to the formula 
Al, O, 2 H, O, then the name bauxite will unquestionably belong to 
this sflaseeriue, and this alone, in scientific nomenclature; that is, if 
Mr. Scrivenor and others fail, as I hope they will, in their efforts. to 
degrade the word bauxite completely. This issue would more than 
ever leave a large and important function for the word laterite as 
a petrographical term. It is this scientific necessity of making 
provision for Al, O, 2H, 0, the bauxite of mineralogy, which makes 
Mr. Scrivenor’s ‘suggestion positir ely harmful, and puts an insuperable 
difficulty in the way of its adoption by geologists. 

Anent the rather misleading statement by Mr. Scrivenor, that 
‘‘in other countries the original definition [of laterite] has been 
abandoned ”’, I can only repeat the fact that the authorities of the 
present generation who have gone seriously into the study of laterite 
are at one as regards the scientific meaning to be attached to the 
term. The French and German schools from their study of African 


Obituary—C. E. Fox-Strangways. 239 


deposits, and most important of all the officials of the. Geological 
Survey of India who have to deal with the type occurrences, are all 
agreed as to the desirability of retaining the use of the term ‘laterite’ 
in much the same sense as I have defined it. The only culprits 
appear to be those who have either ignored the drift of recent 
tendencies in this matter, or who have preferred to attach more 
importance to the vulgar than to the scientific use of the term. 

In conclusion, I fail to see any good reason why both laterite and 
bauxite should not be regarded as very useful scientific terms, the 
former more particularly for petrographical, the latter for mineralogical 
purposes. » 

T. Croox. 
Screntiric Department, ImpertaL Institute, S.W. 


Grotocy oF Bopmin anp Sr. Avsrett.—In our review of the 
Geological Survey Memoir on this district (Gron. Mac., February, 
p. 85) we called attention to the omission from certain portions of the 
work of the initials of the responsible author. We are informed by 
Mr. D. A. MacAlister that the contributions made by the several 
authors to the pages of the Memoir are as follows :— 

Barrow, G.: pp. 12; 27-8, 29-31, 32, 40-4, 63-4, 73-6, 83-91, 119-20, 180-1. 

Fuett, J. S.: pp. 44-58, 56-61, 65-8, 76-9, 93-104, 117, 8. 

MacAuistEer, D. A.: pp. 54-6, 61-3, 64-5, 72-8, 91-3, 105-9, 111, 7, 131-69, 
170-6, 179, 181. 
eee W. A. E.: pp. 1-40, 44, 68-72, 80-3, 109-11, 120-30, 176-8, 179-80, 


OS hap AS ae 


CHARLES EDWARD FOX-STRANGWAYS, F.G.S. 
Born Frepruary 13, 1844. Dizp Marc# 5, 1910. 


We have to deplore the death of Mr. C. Fox-Strangways at the 
age of 66. We give his name here as he wrote it, omitting the 
second initial. 

He was born at Rewe, a village situated on the River Culm about 
434 miles north-east of Exeter. There his father, the Rey. Henry 
Fox-Strangways, a grandson of the first Earl of Ilchester, was Rector.. 
Another relation, the Hon. William Thomas Horner Fox-Strangways, 
had become a member of the Geological Society in 1815, and had 
communicated papers to the Transactions of the Society on the geology 
of Russia, and of the neighbourhood of St. Petersburg in particular. 
He served on the Council of the Society in 1820-1, was elected a 
Fellow of the Royal Society in 1821, and eventually succeeded to the 
title as fourth Karl of Ilchester. 

C. Fox-Strangways was educated at Eton, about the same time as 
his cousin, the late Sir Redvers Buller, and afterwards proceeded to 
the University of Gottingen, where among other subjects he studied 
mineralogy, chemistry, and physics. In 1866, when war was declared 
between Austria and Prussia, he assisted Sartorius von Waltershausen, 
the professor of geology and mineralogy, in burying his precious 
collection of minerals, so as to prevent it from falling into the hands 
of the belligerents. Soon after his return to England, Strangways 


236 Obituary—C. E. Fox-Strangways. 


was appointed, July 20, 1867, an Assistant Geologist on the Geo- 
logical Survey, under Murchison as Director-General and Ramsay as 
Director. He commenced field-work on the western borders of York- 
shire near Todmorden, and was occupied for a time in surveying 
portions of the neighbourhood of Ingleton. Thence he worked east- 
wards over part of the great Yorkshire coal-field and in the country 
around Harrogate, across the Vale of York to the Jurassic and 
Cretaceous rocks of the East Yorkshire moors and wolds, residing for 
some years at Scarborough. Apart from the memoirs relating to these 
areas, which he prepared in explanation of the geological survey 
maps, Mr. Strangways wrote an elaborate general memoir on the 
Jurassic Rocks of Yorkshire. 

In 1889 he was transferred to the Midland counties, and took 
up residence at Leicester until the close of his official career in 
1904. In 1901 he had been promoted to be District Geologist 
when the Geological Survey was reorganized under the Director- 
ship of Dr. J. J. H. Teall; but his retirement at the age of 
60 was rendered desirable by weakness of heart, which at that 
time began to impede his wonted activity in the field. While 
at Leicester Mr. Strangways surveyed in detail the Leicestershire 
eoal-field and prepared an important memoir on the subject; 
but his field-work extended over a much larger area, as indicated 
in the appended list of official publications. He also did a great 
deal to stir up local interest in geology at Leicester, in further- 
ance of which he planned and conducted numerous field-excursions 
in the district, and in 1903 and 1904 to Scarborough and Whitby, 
reports of which were printed in the Transactions of the Leicester 
Literary and Philosophical Society. 

Methodical and painstaking in all his work, his accuracy and the 
care he took in mastering the literature on all subjects he dealt with, 
kept him free from the domain of controversy. It is thus interesting 
to mention that Professor P. F. Kendall, in his important paper on 
‘A System of Glacier-Lakes in the Cleveland Hills’ (1902), refers to 
‘(a great lake in the Vale of Pickering, postulated upon very in- 
conclusive grounds by Phillips and other writers, but demonstrated in 
a very clear and convincing manner by Mr. C. Fox-Strangways’’.’ 

Strangways married in 1868 Annie Maria, daughter of the late 
George Flory of Ipswich, and had no issue. In 1873 he was elected 
a Fellow of the Geological Society, and served as member of Council 
during the years 1905-8. 

He was fond of travel and had journeyed to South Africa, Canada, 
and the United States, and in almost every country in Europe. 
Spitzbergen and Iceland were visited in 1899, with his nephew 
Mr. A. W. Searley, who took a series of instructive photographs, 
some of which were published in illustration of a paper printed by 
Mr. Strangways in 1900 

His chief publications were the numerous memoirs dealing with the 
geology of the districts he had surveyed; and of two of these, the 

1 Quart. Journ. Geol. Soc., vol. lviii, p. 473. | 


2 We are indebted to Mr. Searley for some particulars relating to the life of his 
uncle. 


Obituary—C. E. Fox-Strangways. 237 


memoirs on Harrogate and on the country south of Scarborough, he 
had prepared new editions within the last six years. During the past 
year and up to the time of his death, caused by heart-failure, he had 
been steadily engaged on an exhaustive geological bibliography of 
Yorkshire, and had practically completed this work, after many visits 
to the British Museum and other libraries for the purpose of seeing 
and verifying each record. 

A staunch friend, and a man of most amiable disposition, although 
exceedingly reserved, his loss will long be felt personally as well as 
scientifically, by all acquainted with him and his works. 


List or GEoLocicaL SuRvEY Memorrs. 


1873. The Geology of the Country North and East of Harrogate. 2nd ed., 1908. 
1878. The Geology of the Yorkshire Coal Field. (Notes contributed to Memoir 
by A. H. Green.) 
1879. The Geology of the Country between Bradford and Skipton. (With 
J. ‘R. Dakyns and others.) 
1880. The Geology of the Oolitic and Cretaceous Rocks South of Scarborough. 
2nd ed., 1904. 
1881. The Oolitic and Liassic Rocks to the North and West of Malton. 
1882. The Geology of the Country between Whitby and Scarborough. (With 
G. Barrow. 
1884. The Geology of the Country North-Kast of York and South of Malton. 
1885. The Geology of Bridlington Bay. (With J. R. Dakyns.) 
The Geology of Eskdale, Rosedale, etc. (With C. Reid and G. Barrow.) 
1886. The Geology of the Country between York and Hull. (With J. R.. Dakyns 
and A. C. G. Cameron.) 
The Geology of the Country around Driffield. (With J. R. Dakyns.) 
The Geology of the Country around Northallerton and Thirsk. (With 
A. C. G. Cameron and G. Barrow.) 
1890. The Geology of the Country around Ingleborough. (Notes contributed to 
Memoir by J. R. Dakyns, R. H. Tiddeman, W. Gunn, and A. Strahan.) 
The Geology of Parts of North Lincolnshire and South Yorkshire. (Notes 
contributed to Memoir by W. A. E. Ussher.) 
1892. The Jurassic Rocks of Britain: Yorkshire. 2 vols. 
1900. The Geology of the Country between Atherstone and Charnwood Forest. 
1903. The Geology of the Country near Leicester. 
1905. The Geology of the Country between Derby, Burton-on-Trent, Ashby-de-la- 
Zouch, and Loughborough. 
1906. The Water Supply from Underground Sources of the East Riding of 
Yorkshire. 
1907, The Geology of the Leicestershire and South Derbyshire Coalfield. 
1908. The Geology of the Southern Part of the Derbyshire and Nottinghamshire 
Coalfield. (Notes contributed to Memoir by W. Gibson and others.) 
1909. The Geology of the Melton Mowbray District and South-East Nottingham- 
shire. (Notes contributed to Memoir by G. W. Lamplugh and others.) 


In addition to the various 1 inch and 6 inch geological maps, 
Mr. Strangways prepared a number of Horizontal Sections across the 
Oolitic districts of East Yorkshire which were accompanied by brief 
explanatory pamphlets; and also one sheet of Vertical Sections of the 
Oolites from Filey to Cloughton. 


Lisr or PrincipaL UNorricIaAL Papers. 


1885. ‘*The Harrogate Wells, or the Mineral Waters of Harrogate geologically 
considered’: Proc. Yorks. Geol. Soc., viii, p. 318. 
1894. ‘‘Dr. Alex. Brown on Solenopora’’?: Grou. Mac:, p. 236. 
**The Valleys of North-East Yorkshire and their Mode of Formation”’ : 
Trans. Leicester Lit. and Phil. Soc., iii, p. 333. ‘ 


238 Obituary—Alexander Agassiz. 


1895. ‘Glacial Phenomena near York’’: Proc. Yorks. Geol. Soc., xiii, p. 15. 
1897. ‘‘Geology of the London Extension of the Manchester, Sheffield, and 
Lincolnshire Railway.’’—Part 1: Annesley to Rugby: Grou. Mac., p. 49. 
“Notes on the Stratigraphy of the Newer Rocks of the Netherseal 
Borings’’: Trans. Fed. Inst. M.E., xii, p. 598. 
‘Notes on the Coast between Redcar and Scarborough ’’: Proc. Yorks. 
Geol. Soc., xii, p. 248. 
1898. ‘‘Sections along the Lancashire, Derbyshire, and East Coast Railway 
between Lincoln and Chesterfield ” : Quart. Journ. Geol. Soc., liv, p. 157. 
‘* Filey Bay and Brigg’’: Proc. Yorks. Geol. Soc., xii, p. 338. 
‘Notes on the Coast Sections between Hayburn Wyke and Filey”: 
ibid., p. 356. 
IMD, 6 x otes on Spitsbergen and Iceland’’: Trans. Leicester Lit. and Phil. Soc., 
7, p» 404. 
1907. Aveo ‘‘Geology”’ in the Victoria History of the Counties of England, 
Leicester, vol. i. 
“The Geology of North-East Yorkshire in relation to the Water Supply of 
the District’: Trans. Brit. Assoc. Waterw. Engin., xi, p. 113. 
Article ‘ Geology in ‘A Guide to Leicester and District”: prepared for 
Brit. Assoc. 
1908. ‘‘Notes on the Geology of Leicestershire’’: Rep. Brit. Assoc. for 1907, 


p- 503. 
HB OWE 


ALEXANDER AGASSIZ, 
For. Mems. Roy. Soc. 
Born Drcemper 17, 1835. Dizp Marcu 28, 1910. 

We regret to record the death of this distinguished naturalist on 
March 28 at the age of 74, when returning from Europe to the 
United States on board the s.s. ‘‘ Adriatic”’. 

Born at Neuchatel, Switzerland, December 17, 1835, son of the 
celebrated Professor Louis Agassiz,‘ he accompanied his father in 
1846 to the United States, where the elder Agassiz had been 
appointed Professor of Zoolog ey and Geology in the University of 
Cambridge, Massachusetts. Educated at Harvard, where he took 
his B.Sc. degree at the age of 22, and of which University i in 1878 
he was elected a Fellow, Alexander Agassiz served for a short time 
on the United States Geological Survey. Turning his attention 
shortly afterwards to mining, he speedily proved so successful that, 
having acquired property in the Lake Superior region, he rapidly 
amassed a very large fortune in copper-mines. 

The possession of independent means early enabled him to devote 
his time and studies to natural history pursuits. At first he assisted 
his father as Curator of Comparative Zoology at Harvard, and after 
his father’s death he acted as Curator for eleven years. As his 
wealth increased he became a great benefactor to this Museum, not 
only by purchasing books and specimens, but by gifts of money up 
to £100,000. Commencing with the study of marine ichthyology, he 
subsequently devoted himself to, and became one of the highest 
authorities on, the Echinodermata, so that, on the return of H.M.S. 
‘‘Challenger”’, he was asked to undertake the report on the 
Echinoderms collected during the voyage. 

But the work for which Alexander Agassiz will be chiefly 


1 See obituary of Professor L. Agassiz (1807-73), Gzox. Mac., 1874, pp. 47-8. 


Obituary—Alexander Agassiz. 239 


remembered was that which, during nearly forty years, he carried 
on at his own expense in connexion with oceanography. The United 
States Government, with the greatest liberality and consideration for 
the interests of science, allowed him from time to time the use of 
their surveying vessels, the Captains of which were instructed to 
place themselves virtually under the orders of Agassiz himself. The 
naturalist, aided by a staff selected and paid by himself, carried on 
soundings and dredgings in every part of the globe, special attention 
being devoted to the study of coral reefs. Beginning in 1877 with 
the study of the Gulf of Mexico, the Caribbean Sea, and the Atlantic 
coast of America, Agassiz continued his work in 1880 by investigating 
the surface fauna of the Gulf Stream. Besides working out the 
details derived from the study of collections made during these 
voyages, the results of which were published in connexion with the 
Harvard Museum of Comparative Zoology, Agassiz wrote a well- 
illustrated account of his work, The Three Voyages of the ‘‘ Blake”’, in 
two volumes. 

In 1891 Agassiz transferred his attention to the western shores of 
the United States and Central America, investigating the seas around 
the Sandwich Islands, and paying special attention to the coral reefs 
there, between 1892 and 1894. His explorations were extended 
during 1895-6 to the Great Barrier Reef of Australia, and in 1897-8 
to the Fiji Islands. In 1899 and 1900 he was able to undertake 
a cruise among the various groups of coral islands lying between San 
Francisco and Japan. In 1901-2 Agassiz commenced his study of 
the Indian Ocean, paying especial attention to the Maldive Islands 
and their surroundings; and, in order to complete the examination 
of portions of the Pacific that he had not already visited, he devoted 
the years 1904—5 to a cruise among the important island-groups of the 
eastern half of the Pacific Ocean. 

The intervals between his several voyages were occupied by Agassiz 
in the study of his enormous collections and the preparation of 
memoirs dealing with the results obtained. These were issued, 
regardless of expense as to their illustration, in the publications of 
the Boston Society’s Museum of Comparative Zoology. No fewer 
than thirty volumes of memoirs and fifty-three volumes of bulletins 
are devoted to the results obtained from the study of these collections 
by Agassiz and the various specialists who assisted him. His own 
favourite place of work was Paris, where rooms were always allotted 
to him in the Museum of Natural History, and he had the fullest 
access to scientific libraries. 

Of the value and importance of the results of these voyages it is 
impossible to speak too highly. Perhaps the most striking of the 
conclusions arrived at by him are those relating to great movements 
which have taken place in the bed of the Pacific in comparatively 
recent geological times. This is evidenced by the numerous upraised 
coral reefs which, following Dana, he described; in many of these the 
limestone rock, now at elevations of 1000 feet and upwards, has been ° 
more or less completely converted into dolomite. 

It is not necessary, in face of the above statement of facts, to add 
that Agassiz was a man of indomitable energy. He thought as little 


240 Miscellaneous. 


of crossing the Atlantic as we do of crossing the Thames, and death 
met him at last while still ‘‘on the move’ 

In early life Alexander Agassiz exhibited something of the 
dogmatic habit of mind that distinguished his illustrious father; but, 
mellowed by age and constant intercourse with other men, he became 
in after life strikingly open-minded and ready to listen to arguments, 
even those that told against his most cherished convictions. Those 
who were privileged to enjoy his friendship in his later life knew him 
as a man of ardent enthusiasm, restless energy, and charming 
bonhomie, but also as one patient in discussion, and always ready 
to listen to facts and reasonings from whatever “quarter they came. 
His generosity was unbounded, and he was ever willing to place his 
abundant materials at the service of young men who were qualified 
and desirous to engage in their study. 

In every scientific circle of Europe, as well as in those of America, 
Alexander Agassiz was well known, and in all of them his loss will 
be deeply mourned. In France he received the Légion d’ Honneur, 
and in Germany the Order of Merit. In this country he was since 
1874 a Foreign Member of the Zoological Society, and for many years 
a Foreign Member of the Royal Society. Only last year the Royal 
Geographical Society awarded him the Victoria Research Medal, and 
we may fitly conclude this notice with the verdict of the President in 
announcing the award—a verdict in the justice of which all must 
agree—‘‘ He has done more for oceanographical research than any 
other single individual.”’ ! 


MISCHILUAN HOUS- 


Niece 

Provence Fosstz Inverteprates.—The Geological Department of 
the British Museum has recently acquired a further selection of the 
rarer Mesozoic species from the collection of Mr. A. Michalet, member 
of the Geological Society of France. We understand that Mr. Michalet’s 
cabinets have become so overcrowded that he would be glad to dispose 
of his duplicates to any British colleagues who may desire them at 
a merely nominal price. His address is Allée des Platanes, Quartier 
de la Barre, Toulon (Var). 

Toe Mammora Cave, Western Avsrratta.—In the Records of 
the Western Australian Museum and Art Gallery (vol. i, pt. i, 1910, 
edited by Mr. Bernard H. Woodward), there is an account of various 
mammalian remains obtained from this cave, and described by Mr. L. 
Glauert. The specimens include Phascolomys Hacketti, sp. noy., 
Phascolarctus cinereus (Goldf.), and Sthenurus occidentalis, sp. nov., 
which are figured. 

Grotoetsrs’ Assocration.—A most useful Classified Index to the 
Contents of the Proceedings of the Geologists’ Association, vols. i-xx, 
has been compiled by Mr. G. W. Young and Mr. William Wright. 
It is issued as pt. vii of vol. xxi at the price of 1s. 6d., and comprises 
(1) List of Papers and Lectures, under names of Authors, (2) Subject 
Index to Papers, (3) Index to Localities of Excursions, and (4) 
Chronological List of the Longer Excursions. 


1 Taken chiefly from Professor J. W. Judd’s notice in Natwre, April 7, 1910, 
p. 163. 


- Decade V.—Vol. VII.—No. VI. Price 2s. net, 


CROLOGICAL MAGAZINE 


Honthly Journal of Geology. 


WITH WHICH IS INCORPORATED 


Pees GL @On@©@ Gers 
EDITED BY 


HENRY WOODWARD, LL.D., F.R.S., F.G.S., &c. 


ASSISTED BY 


Proressor J. W. GREGORY, D.Sc., F.R.S., F.G.S. 
: Dr. GEORGE J. HINDE, F.R.S., F.G.S. 
Sir THOMAS H. HOLLAND, K.C.1.E., A.R.C.8., D.Sc., F.R.S., F.G.S. 
Prorressor W. W. WATTS, Sc.D., M.Sc., F.R.S., V.P.G.S. 
Dr. ARTHUR SMITH WOODWARD, F.R.S., F.L.S., Sec.Grou.Soc., anv 
HORACE B. WOODWARD, F.R.S., F.G.S. 


JUNE, 1910. 


CONTENTS. 


IN MEMORIAM: 
H.M. KING EDWARD VIL. 


MAY 6, 1910. 
I. OxtoinaL ARTICLES. Page | ORIGINAL ARTICLES (continued). Page 
On a Collection of Fossil Plants from Glacial Drift at Marros, Pembroke- 
the Newent Coal-field. By E. A. | shire. oy A. L. Leacn. (With 
NEWELL ARBER, M. A 1h, Si a Text- gure.) ae aie A ks: 
1a (GratSia oe 241 | Il. Notices oF ae 
The Glaciation of the Navis Valley, | D. W. Johnson: Southernmost 
North Tirol. By Atrrep P. Youne, | Glaciation of the United States... 280 
Ph.D., F.G.S., F.L.S. (Plates Eiko Ree aes 
XIX and XX and three Text- | Dr. A. E. H. Tutton: Crystalline © 
figures.) ... ae Structure and Chemical Constitution 282 
Notes on New Chalk, Polyzoa, ete. Dr. G. F. Matthew: Geology of the 
By ee Brypons, F.G.S ee Little River Group We ae actif 
(Plate Jive ane 22) Dr. Felix Oswald on Arn ria ysell!@ 9B St) 


The Systematic Position of the 


Dinosaur Titanosawrus. By Baron IV, Reports anp/PRocErDines. 


Geological Society of Liondon— 

Francis Noposa ... 261 8 yor iN : 
The Geology of the Dolgelley Gold- | Ee ee Me, Gh sacar ee 

belt, North Wales. By Arraur pril 27 .. ‘Wy - 285 

R. ANDREW, M.Sc., F.G.S. (Con- Zoological Society of ‘Londo ee; 

eluded.) .. 261 May Giese 4 ation albu at 
The Inferior Oolite Vertebrates of the Nic ‘Onrrvary. ion cen 

Cotteswold Hills, ete. By L. The Rev. W. H. Egerton, M.A., 

Rrcwarpson, F.R.S.E., F.G.8. . 272 BG:0 oy (Bitte SEIT.) 22 28 
The Transition-bed and Crinoidal VI. MiscELLANEOUS. 

Band in the Middle Lias. By Sedgwick Prize Essay ......, ... 288 

A. R. Horwoop, Leicester... ... 274 | Mineral Waters of Essex... ... ... 288 


LONDON: DULAU & CO., Lr., 37 SOHO SQUARE, W. 


k= The Volume for 1909 of the GEOLOGICAL MAGAZINE is ready, 
price 20s. net. Cloth Cases for Binding may be had, price 1s. 6d. net. 


ROBERT F. DAMON, 


WEYMOUTH, ENGLAND, 


Begs to call the attention of Directors of Museums 
and Professors of Biology and Geology in Universities 
to his fine series of 


Coloured Casts and Models 


Rare and Interesting Fossils. 


This interesting and attractive series will form a most 

valuable addition ‘to any Museum of Zoology or 
Comparative Anatomy, and cannot fail to prove of 
the greatest interest alike to men of Science and to all 

Students of Natural History as well as to the general 

body of educated visitors to a public collection. 


A town about to establish a Museum would find that these 
specimens, when properly mounted and displayed in glass cases, 
with instructive labels to each, would form a substantial basis for 
a Public Museum at a very small cost. 

Directors or Curators and Professors of Colleges can abies by 
return of post a full detailed list, and also, if desired, a list of the 
Museums in Great Britain, Australia, ‘Africa, America, Austria, 
Belgium, Brazil, Canada, Denmark, France, Germany, Greece, 
Holland, India, Italy, Japan, New Zealand, Norway, Portugal, 
Russia, and Switzerland, where these Casts may be seen which 
have been supplied by him. 


To prevent delay and disappointment R. F. D. would be greatly 
obliged if intending purchasers would give him ample time to 
execute orders. 


THE 


GHOLOGICAL MAGAZINK. 


NEW. SERIES.“  DEGADIE: Vas. VOL Witt 


No. VI.—JUNE, 1910. 


HIS MOST GRACIOUS MAJESTY 


KING EDWARD VII 
PASSED AWAY MAY 6, 1910, 
BELOVED AND MOURNED BY ALL HIS PEOPLE, AFTER A SHORT BUT 
STRENUOUS REIGN OF NINE YEARS, DEVOTED TO ALL GOOD WORKS 


IN THE BRITISH DOMINIONS AND TO THE WELL-BEING AND PEACE 
OF THE NATIONS. 


ORIGINAL ARTICLES. 


I,—Norrs on a Coxztecrion oF Fosstz Prants From tHE NEWwENT 
CoaL-FIELD (GLOUCESTERSHIRE). 


By E. A. Newert Arser, M.A., F.L.S., F.G.S. 


T has been known for more than a hundred years past that 
a small tract of Upper Carboniferous rocks occurs in North- 
West Gloucestershire, between May Hill and the Malverns. The 
beds crop out in the neighbourhood of Newent, a village lying some 
ten miles to the north-west of Gloucester. The field, however, is 
almost entirely concealed beneath Triassic rocks. The measures are 
productive, and have been worked at various periods on a small scale, 
though the greater portion of the basin remains to this day unexplored. 
The geology of the district was first studied by the celebrated 
William Smith, in 1803 and 1805. In his manuscript notes,! published 
in 1844, there is a section of the sinking at Boulsden, or, as it was then 
apparently called, ‘ Bowsden,’ one mile south-west of Newent, where 
a coal-seam crops out. In the past the coal has been more extensively 
worked at this spot than at any other in the district. 

It is not proposed to enter here into the geology of this tract of 
Carboniferous rocks. What is known on the subject will be found in 
the papers by Weaver,? Maclauchlan,* Murchison,‘ and especially in 
the excellent Survey memoir dealing with the district of the Malvern 


1 J. Phillips, Memoirs of William Smith, 1844, pp. 54, 58. 

2 T. Weaver, Trans. Geol. Soc., 1824, ser. 11, vol. i, pt. ii, p. 317. 

3 H. Maclauchlan, Trans. Geol. Soc., 1837, ser. 11, vol. v, pt. i, p. 203. 

4 R. I. Murchison, Proc. Geol. Soc., 1835, vol. ii, No. 38, p. 121; see also The 
Silurian System, etc., London, 1839, p. 153. 


DECADE V.—VOL. VII.—NO. VI. 16 


242 HE. A. Newell Arber—Fossil Plants, Gloucester Coal-field. 


Hills by John Phillips.1 So far as I am aware no additions have been 
made to our knowledge on this subject since 1848. 

I have for some years past been occupied with a study of the 
distribution of fossil plants in the Forest of Dean, which lies roughly 
between the Newent and Bristol Coal-fields. The flora of the Bristol 
Coal-field has recently been extended and revised by my friend and 
former pupil Mr. Lillie.? My attention was thus naturally turned to 
the Newent tract, and after some correspondence with Dr. Theodore 
Groom, who, I understand, will shortly publish a paper including 
a geological study of this part of Gloucestershire, I visited the 
district last October with a view to collecting such plant remains as 
could be obtained. JI found, as I had anticipated, that there are 
practically no exposures of the Coal-measures at the present time 
which offer any opportunity for collecting fossil plants. I had, 
however, the good fortune to secure the co-operation of Mr. I. Rogers, 
of Bideford, who very kindly spent some days with me at Newent, 
and, to his exceptional skill as a collector, such specimens as we were 
able to obtain are largely due. To him I owe many thanks. I have 
also to express my. indebtedness to a grant from the Government 
Grant Committee of the Royal Society for defraying the expenses of 
the field-work. 

It fortunately happened that, shortly before my visit, a well had 
been sunk at Great Boulsden, about 90 feet deep, on the exact site 
of the old abandoned workings for coal in this locality. The upper 
6 feet, I was told, consisted of red rocks, no doubt Trias, and the 
rest of the section appeared to be Coal-measures. JI was also 
informed that no seam of coal had been passed through, but that it 
was expected that the coal would be reached at a depth of about 
120 feet. At the time when I discovered this sinking, the heap of 
debris thrown out of the well had unfortunately become badly 
weathered, partly owing no doubt to the wet nature of last summer. 
The shales were thus extremely soft and very fragmentary. Collecting 
was performed by means of the blade of a penknife. However, after 
several days work, Mr. Rogers and I managed to obtain a few 
specimens which could be determined specifically, and which will 
be discussed here. 

I may perhaps mention that, through the kindness of Mr. O. T. Price 
of Boulsden Croft, Newent, I obtained some interesting information 
as to the year in which the coal was first worked at Boulsden, which 
does not appear to have been known to those who have written on the 
geology of this district. Mr. Price showed me a copy of the Gloucester 
Journal for April 26, 1890, in which there was an article recalling 
the excitement due to the discovery of coal at Boulsden one hundred 
years previously. Quotations from the Hereford Journal of July 7 
and 14, 1790, were cited in which it was stated that coal had been 
~ raised and burnt in Hereford and Gloucester during the summer of 
that year. The cost then was 16s. a load. Apparently the enterprise 
did not prove profitable, for the shafts appear to have been abandoned 
a few years later. 

1 J. Phillips, ‘‘ The Malvern Hills’: Mem. Geol. Sury., 1848, vol. ii, pf. i. 

* D. G. Lillie, Guot. Mac., 1910, Dec. V, Vol. VII, p. 58. 


E. A. Newell Arber—Fossil Plants, Gloucester Coal-field. 243 


Some thirty years ago, the Newent Colliery Company sank two 
shafts on the site of former workings below White House, about 
three-quarters of a mile due west of Oxenhall Church, to the north- 
west of Newent. These pits have also been long since abandoned. 
By digging, however, in the old waste-heaps of this colliery, Mr. Rogers 
was able to unearth a few fragments of fronds. These were the 
only other specimens which we could obtain, even after a careful 
examination of all the outcrops of the Coal-measures in the district. 

So far as I am aware no plant remains have ever been previously 
collected from this coal-field, nor do I know of any reference to such 
specimens in any book or paper. The fossils discussed here are thus 
unique as regards locality. 

A few fragmentary pith-casts of Calamites occur, one of which is 
possibly Calamites Suckowi, Brongn., but the specimens are too 
fragmentary to permit of specific determination. Two types of 
Calamite foliage were found, a single specimen of Annularia radiata, 
Brongn., and several examples of Calamocladus equisetiformis (Schloth.), 
which appears to be common. 

Among the Fern-like fronds, those of Pecopteris are particularly 
abundant, and probably more so than any other plant. There appear 
to be at least three species. Unfortunately, not only does the 
fragmentary nature of the specimens render them unfavourable for 
specific determination, but the nervation is as a rule very indistinct. 
Pecopteris oreopterrdia (Schloth.), the characteristic nervation of 
which is seen in several examples, almost certainly occurs and is 
particularly abundant. Pecopteris Miltoni (Artis) appears to be also 
common. Other fronds apparently belong to Pecopteris arborescens 
(Sehloth.), but their attribution is more doubtful, for the nervation 
cannot be clearly seen in any example, though specimens do occur in 
which the veins are apparently simple. 

Two small specimens, each showing a few pinnules of Meuropteris 
rarinervis, Bunb., were collected, in which the nerves are very clear 
and characteristic. Fragments of Sphenopterid fronds, recalling 
Sphenopteris obtusiloba, Brongn., were found, but are too small to be 
determined with certainty. 

Small leafy branches of a Lepidodendron are frequent, and the 
characteristic striated bark! of an unknown genus, which has been 
found in several other coal-fields, is also represented. A single, 
poorly preserved leaf of Cordaztes completes the list. 

The above specimens were all collected from the well-sinking at 
Great Boulsden. From the disused Newent Colliery heaps, one or 
two specimens of Weuwropteris Scheuchzert, Hoffm., and a fragment of 
a pinnule with a net nervation, belonging either to Lonchopteris or 
Dictyopteris, perhaps the former rather than the latter, were the only 
plants obtained, with the exception of some Lycopod macrospores. 

The collection from the Newent Coal-field is too small to determine 
the horizon of the beds with certainty. So far as it goes it indicates 
that the zone is higher than the Middle Coal-measures, but whether 
Upper Transition Series or Upper Coal-measures cannot be definitely 


1 See Arber, Phil. Trans. Roy. Soc., ser. B, vol. cxcvii, p. 310, pl. xx, fig. 12. 


244 Dr. A. P. Young—Gilaciation of Navis Valley. 


decided at present. The presence of Annularia radiata, Brongn., and 
to a less extent that of Meuropteris rarinervis, Bunb., would seem to 
turn the balance in favour of the Upper Transition Series were it not 
for the abundance of Pecopterids and the possible occurrence of 
Pecopteris arborescens (Schloth.). Perhaps we may provisionally 
conclude that these beds belong, either to the highest portion of the 
Upper Transition Series, or the lower portion of the Upper Coal- 
measures. 


II.—On tHe Guacration oF tHE Navis Vattey 1n Norra Trrot. 
By Aurrep P. Youne, Ph.D., F.G.S., F.L.S., ete. 
(PLATES XIX AND XX.) 


N a previous paper! it was shown that one prominent topographical 
feature of the Tarntal district, the great cirque called the 
‘Griibl’, could be explained as the effect of erosion by a short ice- 
tongue which formed when the snow-line persisted for a time at about 
2400 metres above sea-level. The basin-shaped hollow of the Upper 
Tarntal was held to be due to another stand of the snow-limit at 
2650 metres. It remains to be seen whether these conclusions are 
supported by evidence of a similar nature collected over a wider area. 


EVIDENCE FOR SNOW-LINES IN OTHER PARTS. 


The drainage basin of the Navis Valley is bounded on the south by 
a well-marked ridge in no part lower than 2250 metres, with several 
summits over 2400 metres; the highest, the Schafseiten Spitze, 
reaches 2604 metres. On the north slope of this ridge is a row of 
corries sufficiently conspicuous to be visible from the north slopes 
of the valley as shown in the photograph, Fig. 1, Pl. XIX. Two of 
these corries under the ridge between Bendelstein and Schafseiten 
Spitze certainly held at one time small lakes; the moraine dams at 
the outer lips are still well preserved at a level of about 2150 metres. 
The corries are evidently the beds of short ice-tongues which formed 
when the snow-line stood for a time at about 2250 or 2300 metres. 

On the northern slopes of the Navis Valley the corries are not so 
well developed. On the east slope of the Mieselkopf? is a well- 
marked amphitheatre, the floor of which is somewhat ill-defined. 
Important accumulations of moraine material are found on these slopes 
mostly at levels below 2300 and above 2150 metres; these evidently 
belong to a high snow-line, the level of which was between 2350 
and 2400 metres. 

Under the ridge which bears the Schober Spitz, 2450 metres, is 
a small but pronounced lake-basin at a level of 2300 metres, indicating 
a snow-line at 2350 metres nearly. 

Summing up the evidence from different parts of the drainage 


1 Grou. Mae., Dec. V, Vol. VI, No. VIII (August, 1909), p. 339. 
2 See accompanying map reproduced from the Grozt. Mac., August, 1909, p. 341. 


245 


y. 


Navis Valle 


ion of 


Glaciat 


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Dr. A. P- Youn 


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246 Dr, A. P. Young— Glaciation of Navis Valley. 
area of the Navis Valley, we have for the probable height of the 


snow-line— 


Metres. 
On slopes with north aspect under the Schafseiten ridge 2250 or 2300 
At the Griibl with west aspect . : 2400 
Slope with south aspect under Schober Spitz 2350 


Slopes with east and south-east aspect under Mieselkopf about 2350 


SrmPLte AND Compound CorRIEs. 


The corries under the Schafseiten Spitze are so simple in form that 
they may have been excavated during a single stage of glaciation. 
The dams being still intact, it is clear that the stand in question was 
made in the course of the last retreat of the ice, marking a late phase 
in the Wiirm period of Penck. An earlier period is out of the 
question; the dams formed would have been swept away by the ice in 
the following advance. 

At the Griibl, the great cirque under the Tarntal, the conditions are 
more complicated, and only to be explained on the assumption that 
the work of excavation commenced during one of the earlier glaciations. 
The rear wall of this cirque is over 300 metres in height. The whole 
of the water draining from the Upper and Lower Tarntal collects 
under the screes and reaches the Griibl in the form of big springs 
which come to the surface little above the floor of the cirque. | 


rie ’ / 
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staffelsee 
Scale of kilometres. 


Fie. 2. Sketch-map of the Tarntal area. 
b, c, d, brow ot steep slope, forming the present rear wall of the Grubl; e¢, f, 
supposed position of the head of the rear wall of the older simple corrie ; hy knolls 
of schist and ‘ Hisendolomit’ at the lip of the Griibl. 


Grou. Mae. 1910. PHATE XIX. 


Fic. 1.—Corries under Schafseiten ridge. 


Bemrose, Collo. 
Fic. 2.—Old Floor of the Griibl; the Cirque under the Tarntal. 


Dr, A. P. Young—Glaciation of Navis Valley. 247 


The annexed diagram (Fig. 2) shows in plan the main hydro- 
graphical features. A pronounced north and south groove ¢, d, is seen 
to end at d at a level of about 2500 metres, just in front of the lower 
end of the Lower Tarntal. This groove was at one time the bed of 
the brook from Upper Tarntal, which was then tributary to the 
Lower Tarntal. By the retreat of the wall the connexion has been 
broken in two places, namely, along the dotted line d¢ and near the 
junction at d. 

At this earlier stage the wall at the back of the Griibl stood further 
to the westward as shown by the broken line e, f. The Griibl was then 
a simple corrie and received the drainage of both the higher valleys 
below the junction at d. Two other important changes have since 
been brought about. The floor of the Upper Tarntal has been further 
excavated so that the level of the latest outlet is lower by some 
20 metres than the old watercourse at 6. The floor of the Griibl has 
also been further eroded. A former level of this floor is no doubt 
indicated by the small plain which now makes a conspicuous feature 
in the landscape as seen in Pl. XIX, Fig. 2. This plain is now some 
20 or 30 metres above the corrie floor. 

In the case of the Griibl the process of ‘gnawing back’ must have 
gone on at an unusually rapid pace, the vertical joints in the 
dolomitic rocks facilitating the work of demolition, most of which was 
effected when the snow-line stood at levels between 2200 and 2500. 

As long as the floor of the corrie was above the snow-line the 
blocks may have been detached in great numbers, but being under 
firn could not have travelled very far. When the snow-line was 
above 2500 the ice-tongues were much reduced in mass and length 
and could contribute little to the transport of the boulders. We 
come back later to the detailed history of the erosion of the Griibl. 


BiocK-waLL AND BuiocKk-wastr. 


The east and west ridge carrying the Reckner and Little Reckner 
summits is almost girdled by a great wall of serpentine blocks. The 
Staffelsee on the south side is somewhat below the foot of the wall. 
The ridge-line of the wall is at 2600 metres, in parts higher. Fig. 3 
of Plate XX is a photograph taken from a knoll about 2600 metres 
high in the Upper Tarntal to the north-west of Reckner. The crest 
of the block-wall is seen projected against the snow-field in the middle 
of the picture and can be traced eastward as far as the contour can be 
followed to the left. 

At first sight the wall might be taken for a moraine, from which, 
however, it differs in the absence of any binding material. Most 
probably it is the result of the demolition which went on when the 
snow-line stood for a time at 2650 metres; the building of the wall 
was thus contemporaneous with the work of the glacier-tongue 
which filled the Upper Tarntal during or since the last retreat. The 
blocks were loosened by alternate frost and thaw, and remained near 
their original site or rolled down the slope by their own weight till 
checked. The pile has no doubt received later accessions and is 
probably increasing still; but its growth was far more rapid when the 
snow-line was lower. 


248 Dr. A. P. Young—Glaciation of Navis Valley. 


This form of disruption without transportation finds a striking 
illustration in the Gross Kaserer, 3270 metres, a subordinate summit 
of the Olperer group. This peak is now and probably has during 
Interglacial periods always been above the snow-line. The great 
crevasses which form between firn and glacier-ice are well developed 
some way below the summit. The appearance presented is that of 
a pile of big boulders; the standing rock is not seen. The massive 
rocks of the Olperer gneissic series break up into blocks too large to 
be disturbed by the movement of the firn. ‘The mound, moreover, 
stands out above the firn and has no permanent covering of snow. 

This mode of disintegration is not confined to glaciated tracts, and 
good examples of disruption with little movement are to be found on 
ancient land surfaces, such as the Indian Peninsula and parts of 
South Africa. In the Alps the ‘Block-meere’ or block-wastes are 
frequent in high ground; most of them were no doubt accumulated 
when the snow-line stood for a time at a corresponding level. 


Kroston 'o-pay In Hiew Grovunp. 


The effects of erosion hitherto treated belong as regards the Tarntal 
mass to past history, and are referred to conditions of clhmate other 
than those at present here prevailing. As already shown,’ the 
climatic snow-line is still, in all probability, below the highest 
summits, and it is instructive to watch the forms of atmospheric 
activity of to-day. 

The serpentine blocks above 2600 metres are covered with wart-like 
prominences a centimetre or so in diameter; these warts are found 
occasionally on standing rock nearly up to the summits. They are 
due to the rapid weathering of the serpentine round the more resistant 
bastites which form the projecting parts. The prominences are seen 
on blocks below 2600 metres; at the lower levels, however, they are 
much worn down and do not seem to be forming afresh. The chief 
agent in this form of weathering is the nearly pure water trickling 
from the melting snow which covers the ground for a considerable 
part of the year. 

An instance of the same kind of work is furnished by the well- 
known ‘Karren’. ‘This form of sculpture is peculiar to calcareous 
rocks; straight grooves resembling the ruts of cart-wheels are crowded 
together in parallel series and often cover wide areas, the ‘ Karren- 
felder’.? The ruts are determined by structures in the limestone, 
thin bands, bedding-planes, joints; they were no doubt formed under 
snow, when the snow-line stood at a corresponding level, and are due 
to the solvent action of nearly pure water. The ‘Karren’ are only 
found at high levels; they may be expected to furnish useful 
information concerning former stands of the snow-line. 

A steep slope on the south side of the saddle between Reckner and 
Little Reckner is covered to a depth of several feet with an incoherent 
deposit of more or less finely divided serpentine almost free from 


1 See Grotocicat Macazinz, August, 1909, p. 346. 

2 Only the simplest form is here described. For details and figures see Max Eckert, 
‘Das Gottesacker, ein Karrenfeld im Allgiiu’’: Wiss. Erginzungsheft zur Zeitschrift 
der D. und O. Alpenverein. 


Dr. A. P. Young—Glaciation of Navis Valley. 249 


vegetation. Except for the presence of some larger rock-fragments, 
the material may be compared with the loose ash which collects round 
the crater of Vesuvius, with which, however, as regards origin, it has 
nothing in common. 

The loose powder on the Reckner slope must be constantly carried 
downward by the melting and falling snows, and to the same extent 
renewed. We have here a hint of the way in which a rock may dis- 
integrate at the level of the snow-limit, and perhaps under the action 
of firn, where alternations of frost and thaw play an important role. 


Orper CHannets oF Uprrr TARrnrtrAt. 


The higher and older outlet channels on the west side, by which 
the Upper Tarntal once drained into the north and south channel 
(¢, d, Fig. 2), are thickly strewed with erratic blocks of Reckner 
serpentine. Judging from the amount of demolition and erosion 
which has been effected since these channels were used, they must 
have been first formed during one of the older glaciations, or at any 
rate before the last general advance. But the presence of erratics in 
these old watercourses implies a movement of ice at a level of 
2550 metres, and a corresponding snow-limit above the ice and below 
the summit ridge; in other words, the snow-line must have made an 
early stand at 2650 metres nearly. The date of this resting stage 
could hardly have been later than the close of the Riss period or the 
first advance of the Wiirm glaciers. Since the serpentine blocks were 
left in these high channels the rear wall of the Griibl has been cut 
back by ice, which could only work efficiently as long as the snow-line 
remained near the level of 2400 metres. 


GuacraL Hisrory. 


The history of the Griibl can only be written on the assumption 
that the snow-line stood on two different occasions at or near 
2400 metres, and, again, twice at about 2650 metres. The sequence 
of events was somewhat as follows:—(1) The older corrie of the 
Gribl, with the higher floor and the rear wall to west of the present 
one, was formed during a sojourn of the snow-line at 2400 metres, 
when the Riss glacier was in retreat. (2) At a later stage of the 
same glaciation, or in the first forward movement of the Wiirm, the 
basin of the Upper Tarntal was excavated down to the level of 
the higher outlets (d), while the snow-line persisted at 2650 metres. 
(3) During the final retreat, that of the Wirm glacier, the snow-line 
again stood at 2400. On this occasion the floor of the Gribl was 
lowered and the demolition of the rear wall broke down the connexions 
at 6 and d, as related above. (4) Lastly, a second stand above 2600 
metres reduced by 30 metres the floor-level of the Upper Tarntal, the 
north-west outlet was pierced and subsequently dammed, since which 
no advance of the ice has taken place. 

Incidentally it may be observed that as far as this evidence goes 
there is no necessity to suppose that the snow-line ever rose above 
2650 metres during the interval between the Riss and the Wiirm period. 
The climatic snow-line to-day is here at least as high as 2750 metres. 


1 See Map, Fig. 1, p. 245. 


250 Dr. A. P. Young—Glaciation of Navis Valley. 


The question whether the last stand at 2650 metres was an event 
in the closing history of the Ice Age as the Daun advance, or merely 
a recent incident of climatic oscillation, is left undecided. 

The level of the snow-line when it stood for a second time over the 
Griibl may have been somewhat lower than the first stand near 
2400 metres ; so also the second stand in the Upper Tarntal may have 
been somewhat under 2650 metres, the new floor in both cases being 
lower than the old. 

Tue Navis Vattry Drirr. 


The assumption underlying all the above conclusions, namely that 
snow-line and firn-line coincide, is safe enough as regards the small 
glaciers of the corries, and is probably not far from the truth in the 
ease of the glaciers taking their rise in the Tarntal Mountain, 
especially during the retreating stages, when the area covered by 
firn and snow was never very large. It may, indeed, be doubted 
whether at so high a level as that of Navis (1343 metres) any glacier- 
ice was contributed by the firn from the Tarntal during the extreme 
of the Wiirm period, when the snow-line was below 1200 metres at 
the northern border of the Alps. 

On the evidence of erratics from the Central Alps, it has been 
inferred that the ice-surface in the Inn Valley during the last 
maximum of cold must have reached a height of 1800 metres or 
more.’ The snow-line in these parts could not at the time have 
been higher than 1200 metres. The significance of the evidence will 
be considered later. It seems that under circumstances massive ice 
may accumulate much above the level of the snow-line at the place. 

The Inn Valley glacier in this case must have formed a high dam 
in front of its tributary the Sill.* It does not follow from this that 
the ice in the Sill Valley rose to the same high level. The ice 
flowing from the Inn up the Sill Valley was retarded by friction and 
wasted by ablation. It met the Sill glacier at the point at which the 
two tongues had equal amounts of moving energy. The Navis Valley 
in turn was dammed by the ice of the Sill, and it is important to 
determine the height of the ice-surface in this valley during the 
Wiirm period. 

At a level of 13800 metres, close to the settlement of Navis, are 
found some blocks of gneiss which could only have been brought by 
the ice of the Sill Valley (or Wipptal) to which the Navis is tributary. 
The blocks probably came from the Olperer Alps. They were borne 
down the Sill tributary in the Valsertal, and were carried by the back 
flow of the Sill ice into their present position. 

I learn from the Pfarrer of Navis, who first called my attention to 
these blocks, that the stone is in good demand for building purposes, 
and that one big boulder of gneiss has been quarried completely away. 
I take this opportunity of expressing my thanks to the Pfarrer, the 
Rev. Johann Schileo, for this and for much welcome information 
concerning the topography, many useful names being incorrectly given 
or omitted altogether on the maps. 

1 A. Penck & E. Briickner, Die Alpen vm Liszeitalter, 1907-9, pp. 268, 1148. 

* See Map, p. 341 of this Magazine for August, 1909. The Sill is the stream 
shown on the western border of the map, reproduced here on p. 246. 


Dr. A. P. Young—Gtaciation of Navis Valley. 251 


The highest level reached by these gneiss blocks cannot therefore be 
precisely known. But the valleys of the Klamm and Weidereich 
brooks which join to form the Navis are hardly accessible enough from 
the inhabited parts to have been exploited by cottagers in search of 
stone, and it is unlikely that the Sill erratics were carried much above 
the level of Navis even during the period of extreme glaciation: to 
which their transport is to be referred. 

In the Klamm Valley, just above Navis at about 1400 metres, is 
a conspicuous bar of moraine material, so little above the point reached 
by the crystalline erratics that it may well mark the site at which the 
Klamm Valley glacier was met by the back-flow of the Sill ice. It is, 
however, more likely that this is the end moraine which was formed 
by the Tarntal ice-tongue during a retreating stage of the Wirm, 
at which time it may be supposed that the Sill ice was also in retreat. 
In either case the ice-surface could not have stood much higher than 
1500 metres. The valley drift which in a measure determines cereal 
cultivation does not reach above 1600 metres, and may belong in part 
to an older glaciation. 

In one part of the Navis Valley, on the north side near the Wetter- 
kreuz at 2151 metres, there is a marked change in the surface gradient, 
the slope being much steeper below the Wetterkreuz than above it. 
If this ledge is the rim of an ice-trough it most likely belongs to one 
of the earlier glaciations, when the floor of the valley and the snow- 
line were both higher than they were during the latest, the Wurm 
glaciation. But the gently sloping floor above the Wetterkreuz may 
be accounted for as a plain of nival denudation, the ‘ Abtragungsebene 
der Schneegrenze’ of Richter.!| The masses of moraine material above 
2200 metres which accumulated during the persistence of the 2400 
metre snow-line make this explanation the more acceptable. Taking 
all the evidence together, it appears most improbable that the ice- 
surface was at 2100 metres when the Schafseiten corries were last 
occupied by ice, or even when they were first formed, supposing them 
to have been more than once filled with ice. 

Of the four resting-stages which have left their traces in the 
Tarntal district two may be doubtfully correlated with Glacial periods 
recognized elsewhere. 

The bar or ‘ Riegel’ at 1400 metres in the Klammbach may be the 
equivalent of the moraine deposits above Trins in the Gschnitztal, the 
‘Gschnitzstadium ’ or , stage of Penck. The Trins glacier rising in 
the high ground of the Stubaital Alps would naturally end at a lower 
level than the glacier of the same date in the Navis Valley with 
a much smaller feeding-ground. It should, however, be noted that 
the terminal moraine of the y stage is placed by Penck at the mouth 
of the Navis Valley.?, The post-Wiirm snow-line of the Griibl at 
2400 metres would appear to be somewhat higher than that of the 
y stage of this valley, to which Penck assigns a level of 2100 metres. 
For the Gschnitztal the snow-line of the y stage is fixed at 2300. 


| E. Richter, ‘‘ Geomorphologische Studien in den Hoch-Alpen’’: Petermann’s 
Mittheilungen Ergdnzungsheft, 1900, vol. cxxxu, p. 77. 
2 Penck & Briickner, Die Alpen im Hiszeitalter, 1907-9, p. 343. 


252 Dr. A. P. Young—Glaciation of Navis Valley. 


On the analogy of the present nival gradient the ancient snow-limit 
in the Navistal should have been lower than in the Gschnitztal. 

The latest post-Wiirm stand recognized in the Tarntal at about 
2650, certainly not lower than 2600 metres, represents a depression 
below the present snow-line of about 150 metres. It may turn out to 
be the equivalent of the Daun stage, when the snow-line is supposed 
to have been lowered to the extent of 300 metres." 

The two pre-Wiirm stages of the Tarntal with snow-lines at 2400 
and 2650 metres respectively cannot be identified with any of the 
stationary periods hitherto recognized. 


Dertinition: ‘Nrvat Pranse’ anp ‘ Nrvat GRADIENT’. 


In the discussion which follows account must be taken of the 
contemporary variation in the height of the snow-line in different 
parts of the Alps. 

The small map compiled by Hess* from a great number of 
observations shows the present snow-line near the central ridge some 
800 metres higher than that on the border of the region now covered 
by snow. 

The imaginary surface containing all the different snow-lines of the 
same period may be called the ‘nival surface’, or more simply 
‘nival plane’. The latter term is sufficiently appropriate to present 
conditions ; the rise of the snow-line over considerable spaces being, 
as Hess’s map shows, nearly proportional to the horizontal distance. 
The angle made with the horizon by the nival plane is the ‘nival 
gradient’. 


User or Mars 1n TracInc ANCIENT SNOW-LINES. 


In order with the help of maps to trace over a wider area the 
extension of the snow-line during any one stationary period, it is 
necessary to know for each stage the orientation of the nival plane; 
only in this way will it be possible to sort correctly into their 
respective groups all the traces of the several nival surfaces. | 

The snow-line in the Alps of to-day is, as we have seen, found to 
rise as much as 600 or 800 metres as the axial ridge is approached 
from the border of the snow-covered district. The change in level 
is no doubt mainly due to variation in the amount of annual 
precipitation, the belt of maximum rainfall being in places as low 
down as 1800 metres,*® seldom much above 2000 metres.* 

It cannot on @ prior? grounds be assumed that the zone of maximum 
precipitation stood at the level at which it is found to-day, or that it 
varied according to any definite rule with reference to the position of 
the nival plane. It has, however, been inferred from the heights of 
corrie-floors and other evidence that the snow-lines of previous cold 
periods ran on slopes approximately parallel with that of to-day.® 


' Penck & Briickner, Die Alpen im Hiszeitalter, pp. 348, 639. 

> H. Hess, Die Gletscher, 1904, p. 74. 

3 Tbid., p. 44. 

4 J. Hann, Handbuch der Klimatologie, 1908-10, p. 258. 

5 A. Penck & E. Briickner, loc. cit., p.1144. E. Richter, Gletscher der Ostalpen, 
p- 277 (quoted by Penck). 


Dr. A. P. Young—Glaciation of Navis Valley. 253 


KaRWENDEL GEBIRGE. 


Professor Rothpletz has called attention to the corries! of the 
Karwendel Gebirge, and much can be learnt from his work? and 
the large scale-map which accompanies it. 

Interpreted according to the method here used, the corries of the 
outermost chains of the Karwendel give evidence of one or two snow- 
lines at a lower level than those observed in the Navis district. The 
Great Soiernkessel on the north side of the ridge is a characteristic 
corrie. ‘he floor at 1546 metres is marked by a lake with a dam of 
standing rock.* The ridge at the back bears several summits higher 
than 2000 metres, the highest, the Soiernkarspitz, reaching 2260 metres. 
This indicates a long stand of the snow-line in the neighbourhood of 
1700 metres. 

The Krapfenkar and Mondscheinkar, also in the ‘ Vordere Kar- 
wendelkette’, have floors at 1700 or 1800 metres, under ridges of 
2100 metres, indicating a stand of the snow-line at 1850 metres 
nearly. The floors appear to be ill-defined, and the stand in question 
is probably to be referred to one of the older glaciations. The higher 
lake of the Soiernkar at 1836 metres may belong to this stage. 

In the ‘ Hintere Karwendelkette’, south of the last-named ridge, 
are several corries with floors at 2100 to 2300 metres. The summits 
on the ridge reach heights of 2550 to 2750 metres. This requires 
a snow-line at 2350 metres or higher. These corries may be companions 
of the Griibl and Schafseiten group of the Navistal. 

Traces in other parts of the Alps of the 2650 metre snow-line should 
be sought in the first instance on ridges of the same height as the 
Tarntaler Kopfe (Reckner, 2891 metres) and at the same distance 
from a high snowy range as Tarntal is from the Olperer. 

About 3 kilometres south of the Sonklarspitze in the Stubaital 
Alps is a ridge of the required height. Several summits reach 
2880 metres, and one, the Scheiblehner, rises to 2991 metres. Just 
below is a large lake, the Schwarzsee, 2548 metres above sea. This 
lake-basin may well be a contemporary of the corrie of the Upper 
Tarntal. The above details are taken from the Austrian General- 
stabskarte, Sheet Solden. 

The Scheiblehner is nearer to the Central Alps than the Tarntal, 
and according to analogy the corresponding snow-line should be 
somewhat higher. More precise determinations of levels may show 
this to have been the case. 


DernupatTion UNDER Firn anp Snow. 


On the slopes of snow-covered mountains there must be a belt of 
the land surface at which the frequency of the oscillations of 
temperature about the freezing-point of water isa maximum. (Here 


1 The corrie is a feature which gives the motive for topographical names. The 
equivalents for ‘ corrie’ in other languages will be useful. They are: Welsh ewm, 
Norwegian or Danish Bodt, pl. Bodter, German Kar, pl. Kare, also circus, French 
cirque, Spanish hondon, Indian (Quecha) ewchyu; the last two names are used in the 
Equatorial Andes (W. Reiss). W. Reiss & A. Stiibel, Das Hochgebirge der Republik 
Ecuador, 1902, ii, p. 164. 

2 A. Rothpletz, Das Karwendelgebirge. 

Setbid.. p: 0e 


204 Dr. A. P. Young—Glaciation of Navis Valley. 


the surface under the ice-tongue is not considered.) This zone does 
not necessarily coincide with the snow-line; it is to be sought 
near the isotherm of 0°C. of mean annual temperature, which in the 
Alps is probably above the snow-line.’ It may be that the standing 
rock under the firn is subject to frequent alternations of the kind in 
question; the changes may then be determined by variations of 
pressure and other causes only indirectly dependent on the temperature 
of the air; the freezing-point under a heavy cover of firn may be other 
than zero Centigrade. 

Above the zone indicated the oscillations of temperature about 
freezing-point diminish in frequency with the height, for not only is 
the mean annual temperature reduced, but the range of temperature- 
variation is narrowed in ascending,” and if denudation still goes on it 
must be due to other causes. 

It might be expected that a study of the volcanic cones which 
project above the snow-line would throw light on the question 
whether a cover of firn serves to protect the land surface. From the 
observations of E. Richter* in the Alps, I. Russell* on Mount Rainier, 
W. Reiss*® in Ecuador and Colombia, it seems clear that the glaciers 
at the snow-line are the most active agents of destruction. According 
to Russell the work of demolition goes on with the greatest activity 
along the crevasses which form at the firn-line. The beds of the 
glaciers are continually receding, with the result that, to use Richter’s 
phrase, the mountain is ultimately beheaded at the snow-limit. 

The outlines of extinct volcanoes which have been long subject 
to this levelling action are well shown in Hans Meyer's photo- 
graphs of Sincholagua and Quilindana.® In the latter figure the 
plain of nival denudation is especially conspicuous. The sketches 
given by A. Stiibel,’ preserving, as they do, the correct relation 
between vertical and horizontal dimensions, are also instructive. 

Russell* maintains that above this zone of rapid disintegration the 
ground is protected by the snow and firn, especially at higher levels, 
where the snow retains the powdery form until it is removed by the 
wind or falls to lower levels. 

Admitting the facts, the proof that a cover of firn or snow retards 
erosion is still incomplete. In estimating the comparative rates of 
erosion all the variables must be taken into account, for example— 

(1) The amount of precipitation varies with the height above sea. 
It reaches a maximum in the Alps at 1800 to 2400 metres, and above 
this level diminishes with the height. In other regions, with average 
rainfall, this maximum is accordingly to be looked for at levels below 
the snow-line. 


1 See J. Hann, Handbuch der Klimatologie, p.268. Inthe Eastern Alps near Innsbruck 
the temporary isotherm 0° C. is below the snow-line only during the winter months. 

2 H. Hess, loc. cit., p. 41. 

3 E. Richter, Geomonphologische Studien in den Hoch Alpen. 

4 I. C. Russell, ‘‘ The Glaciers of Mount Rainier ’’: U.S. Geol. Surv. Reports 
for 1896-7 (1898), vol. xviii, p. 382. 

5 W. Reiss & A. Stiibel, Das Hochgebirge der Republik Eeuador, 1902, ii, 
pp. 165, 173. 

6 Hans Meyer, In den Hoch-Anden von Ecuador, Berlin, 1907. 

7 Die Vulcanberge von Ecuador, p. 407. 8 J. Russell, loc. cit., p. 382. 


Dr. A. P. Young—Glaciation of Navis Valley. 259 


(2) On slopes at lower levels, where local precipitation is reinforced 
by the flow from above, the activity of water must be greater than on 
the high ridges which receive only the snow or rain falling directly 
on them. 

RELATION OF THE CORRIE-FLOOR TO THE SNOW-LIMIT. 

In general, reliable evidence for any one stand of the snow-line will 
be found on suitable slopes under ridges which rise only a few hundred 
metres above the snow-limit. ‘his is the condition for the formation 
of corries. In such cases the ice-tongues will be short, the firn-line 
will coincide with the snow-line. 

Under higher ridges the ice-tongues of the same period will be 
longer, the beds will be in the form of troughs rather than basins. In 
still higher ground the beds of glaciers belonging to successively 
higher snow-lines will join to form a continuous groove, which gives 
no indication of a stationary period. 

Further, low ridges too near the centres of glaciation will be 
whelmed in ice from the high ground. Corries will thus be formed 
only near the border of the tract for the time being under glacial 
conditions, the different stands of the snow-line will leave their traces 
on successively higher ridges nearer the centre, the lowest corries 
corresponding to maxima of cold being on the extreme border of the 
area occupied by ice. Such is, in fact, the distribution of corries 
actually observed. 

All pronounced corries are held to bear precise and unequivocal 
testimony to some one stand of the snow-line, during which the ice 
just filled the hollow. None of this evidence can be neglected. 
Corries with moraine dams must have been filled with ice during the 
latest retreat, the loose material being unfitted to withstand the 
thrust of moving ice of any later advance. 

The basin-like hollow of the corrie is the counterpart of the trough 
occupied by the long glacier tongue. Amphitheatres with ill-defined 
floors are either the sources of longer ice-streams or are the walls of 
ancient corries, the floors of which have been broken down by 
a subsequent advance of the ice. 

This explanation of the origin of corries differs somewhat from those 
hitherto in use. The site of the corrie was determined by the height 
of the snow-line, the height of the ridge, the catchment area, the 
conditions of precipitation and insolation on which depended the 
length of the ice-tongue. A watercourse or groove led the firn in 
the required direction. There was no other marked hollow. Where 
several corries are found at nearly the same level it cannot be supposed 
that each was determined by a pre-existing pit or funnel.! The 
formation of corries is not limited to extremes of glaciation. At the 
time the corrie was formed the snow-line was not on the level of 
the floor,” but considerably higher. The level of the corrie-floor is in 
no way related to the level of the ice-surface in the main valley to 
which the corrie-watercourses were tributary.® 


- | See James Geikie, The Great Ice Age, 1894, p. 237. 
2 See Bohm, Die alten Gletscher der Mur und Miinz, 1900, p. 19; also Richter, 
Geomorphologie, pp. 15, 75. 
3 See Penck, Die Alpen im Hiszeitalter, p. 285. 


256 Dr. A. P. Young—Glaciation of Navis Valley. 


If the views here set forth be correct, the lip of the corrie marks 
the lower end of the ice-tongue under which the basin was excavated ; 
the boundary of the glacier is defined by the lip and the watershed 
of the catchment area above it. By means of these data some precision 
could be introduced into the computation of the corresponding snow- 
line. Briickner’ has found that about one-third of the whole surface 
covered by a glacier belongs to the tongue; thus the contour-line 
which marks off the lower one-third portion from the upper two-thirds 
of the glaciated area is the snow-line. Where contoured maps on 
a large scale are available, a rule such as this, though empirical, 
should give good results in the case of corries, the areas dealt with 
being small. 

Erosion UNDER THE ICcE-TONGUE. 

The direct action of glacier-ice in wearing and scouring the standing 
rock is here accepted as an established fact. It has not been thought 
worth while to qualify the terms in which this postulate is implied. 
For the purpose of this paper, however, it would suffice to assume 
merely that the bed of a glacier tongue differs distinctly in form or 
dimensions” from that of a channel eroded by running water alone. 
The truth is that all conclusions hitherto drawn regarding the relative 
rates of erosion by ice and by water are of doubtful validity. The 
two processes cannot be observed apart. 

The facts to be taken into account are— 

The glacier tongue being below the snow-line, where all the snow 
that falls within the year melts within the year, the whole of the 
local precipitation must reach the land surface under the ice as 
running water by the numerous clefts which form at the firn-line 
and below it. Generally, however, the channels in the ice deflect 
the water, which thus reaches the bed not at the point directly under 
the spot at which it falls, but lower down the valley. 

Some snow above the firn-line melts and reaches the bed to form 
part of the stream. The snow-line is only the limit at which the 
falling snow just balances the melting snow. 

The whole of the glacier-ice is contributed by the firn, that is, by 
a part of the precipitation above the snow-line. By ablation this all 
joins the stream at various points above the lower end of the 
ice-tongue, so that the water running out at the ice-portal during the 
year is exactly what with the same amount of precipitation would 
flow over the bed at this place if no glacier existed. 

The glacier-bed is a water-channel as well as an ice-channel; the 
form taken by the bed is due to the combined action of water and ice. 


GRADIENT OF GLACTIER-ICE. 
The gradient of the ice surface during the last maximum of cold 
has been inferred from a great number of records by various observers 


1 Briickner, Meteorologische Zeitschrift, 1887, p. 31. Hess, Die Gletscher, p. 74. 
The ratio actually observed diverges widely in extreme cases from Briickner’s mean. 
Richter holds that the proportion of glacier-ice to firn is, as Briickner himself hints, 
more nearly 1:4 than 1:3 (E. Richter, Gletscher der Ost Alpen, 1888, p. 41). 
Hess adopts the ratio 1 : 31 (loc. cit., p. 88). 

2 See A. Penck, ‘‘ Uebertiefung der Alpentiiler”” : Internat. geogr. Congress, 1899, 
p. 289. - 


Dr, A. P. Young—Glaciation of Navis Valley. 207 


who have noted the highest occurrences of ice scratches and erratics in 
different parts of a valley. In the application of this method some 
caution seems to be necessary. On the analogy of present conditions 
and on the ground of direct observations, it may be admitted that the 
nival gradient was, at least in the higher ground, always as steep as 
it is to-day. It is perhaps not out of the question that massive ice 
formed above the snow-line even in the high: ground. But if the rise 
in the snow-line was due to diminished precipitation it is difficult to 
suppose that the firn-line stood very much higher than the snow-limit. 
Eyen assuming for the maximum of cold a somewhat steep nival 
eradient and a firn-line high above the snow-line, it can hardly be 
doubted that ice would form at successively higher levels during the 
retreat. The highest scratches may thus belong to milder periods; 
so too the highest boulders in ground near the centre of glaciation. 

The highest crystalline erratics in the neighbourhood of the Alpine 
foot-hills no doubt belong to a period of extreme cold, but not 
necessarily to the last maximum ; boulders of earlier glaciations might 
persist for an indefinite time if landed between the tributary water- 
courses on shoulders and spurs where they would not be disturbed by 
the ice of a subsequent advance. 

The inclusion in the estimate of boulders and scratches belonging to 
retreating stages would give for the maximum an ice-gradient steeper 
than was actually attained in the higher parts of the valleys. To 
include in the estimate boulders which were landed during some 
older glaciation when the valley-floor was higher would lead to false 
conclusions as to the thickness of the ice in the lower reaches of the 
valleys. 


RELATION BETWEEN Nivat Prane anp Zone or Maximum 
PRECIPITATION. 

The hypothesis that the rise in the snow-limit is mainly the result 
of diminished precipitation in the high ground leads to some interesting 
deductions concerning the relation between nival surface (N.S.) and 
belt of maximum rainfall (M.P.). At the present time the nival 


Fie. 3. Diagram showing break in the nival gradient when the nival surface passes 
through the zone of maximum precipitation. 

surface (N.S. 1, Fig. 3) on the northern slopes of the Alps is nearly 
a plane,’ all parts of which are above the zone of maximum rainfall.’ 
With these conditions as a starting-point we may consider the following 
hypothetical cases :— 

Case 1. If while M.P. remains stationary N.S. is depressed 
continuously, it takes up successive positions as N.S. 2, nearly 


1 Penck & Brtickner, Die Alpen im Hiszeitalter, p. 604. 

? See Hess’s map, loc. cit., p. 74. 

3 Hess, loc. cit., p. 44; J. Hann, Kimatologie, 1905, p. 262. 
DECADE V.—VOL. VII.—NO. VI. 17 


258 R. MW. Brydone—New Chalk Polyzoa, ete. 


parallel to N.S. 1, until it falls so low as to pass through M.P., as at 
C.D. Then that part of the nival surface beyond M.P. will not be in 
the same plane with C.D., but will be horizontal nearly, or may even 
rise in the contrary direction if the outer ridges like K. are too small to 
cause by their own mass a marked increase in the precipitation (Fig. 8). 
This break will be maintained as the nival surface continues to fall. 

Case 2. As N.S. falls M.P. is depressed to the same extent, but 
the amount of precipitation remains constant. In all the new positions 
N.S. remains parallel to N.S.1. The supply of firn in the high ground 
is much reduced. 

Case 3. As in the last case M.P. falls at the same rate as N.S., but 
the amount of annual precipitation is much increased. 

Case 1 seems to be inconsistent with parallelism of the nival planes 
through all stages of glaciation. Seeing, however, that the zone of 
maximum precipitation stands in winter at the level of 1000 metres 
or lower,! this difficulty would vanish if it could be shown, as Penck 
suggests,’ that during the ice period the precipitation took place 
mostly in the coldest part of the year. But with this modification 
case 1 is open to the same objection as the following one. 

The hypothesis that N.S. and M.P. rise and fall in company is the 
most probable one. Case 2 does not, however, provide for a supply of 
ice sufficiently copious to fill the lower reaches of the valley up to or 
even above the level of the local snow-line, as seems to have happened 
in the Inn Valley during extremes of cold.? 

It remains to consider whether case 3, which would account for 
some of the most salient facts of Alpine glaciation, is admissible. 


EXPLANATION OF PLATES. 
Prate XIX. 


Fig. 1. Corries on the north slope of the ridge between Schafseiten Spitz (2604 
metres) and Bendelstein (2422 metres). From a point on the slope of 
the ridge east of Mieselkopf, distant about 6 km. Looking south. 

Fig. 2. The horizontal surface a little above the middle line of the picture, probably 
a plain of nival denudation, is held to indicate a former level of the floor 
of the Griibl, View taken from a point about 2100 metres above sea 
on the slope under the Schoberspitz, distant about 1 km. Looking 
south-east. 

Pirate XX. 

Fic. 3. Wall of serpentine blocks forming an almost complete girdle round the 
Reckner ridge at a level of 2600 metres and upwards. From a knoll in 
the Upper Tarntal 2600 metres above sea, distant about 0°75 km. 
Looking south-east. 


TII.—Nores oN NEW OR IMPERFECTLY KNOWN CHatk Poxyzoa. 
By R. M. Brypong, F.G.S. 
(PLATE XXI.) 
(Continued from the April Number, p. 147.) 
Mempranivora Woopwarpi,‘ nov. Pl. XXI, Figs. 1-3. 
Zoarium free or adherent, always unilaminate. 
Zowcia large, subpyriform, with broad margins sloping slightly 
inwards and expanding at the foot into a short front wall; areas 
1 J..Hann, Handbuch der Klimatologie, 1905, p. 262. 


2 Penck & Briickner, loc. cit., p. 1145. 
3 Loc. cit., p. 268. 4 Dedicated to the Editor. 


‘ISPII-LOUYOoY Lepun [[VM-Yoo—'e ‘piq 


‘XX GLyIg ‘OL6L “OVI “TOW+) 


Rh. M. Brydone—New Chalk Polyzoa, ete. 259 


elliptical, length -5 to °75 mm., breadth -31 to *45 mm., tapering 
towards the head, across which stretches a slight internal shelf, which 
straightens the apparent outline; from the edge of this shelf hangs 
a stout oval ring, which connects it with the floor of the zocecium ; 
zocecial boundaries distinct. 

Oewcia very large, almost square; the free edge runs out over the 
area for a short distance and is then cut back in a curve parallel to 
the edge of the area beneath. 

Avicularia subvicarious, forming the initial zocecia of new rows; 
they are practically small and narrow zocecia pinched together at the 
top into a beak and spanned slightly below the middle of the area by 
a very slender bar, of which only the broken ends are usually 
preserved ; in the immature stage found in the JL. cor-anguinum zone 
this beak is very short and markedly unsymmetrical, in the higher 
zones it is greatly produced and nearly or quite symmetrical. 

Found occasionally in the zones of IL. cor-anguinum and Marsupites, 
and freely in the zone of Act. quadratus in Hants and in the zone of 
I. cor-anguinum at Gravesend. 


MEMBRANIPORA CORALLIFoRMIS, nov. Pl. XXI, Figs. 4 and 5. 


Zoarium adherent, sometimes tuft-shaped, but very generally forming 
long narrow bands. 

Zowcia elliptical, very small; length of area -24 to :'3mm., breadth 
"15 to °2mm.; primarily they are quite simple, but along the walls 
of mature zocecia there forms a thick, continuous, smooth incrustation 
pierced by numerous short tubes, giving it a madreporiform appearance; 
the tubes show a weak tendency to regularity of occurrence, there 
being usually a pair, one on either side of the upper part of the area; 
this incrustation may overhang the area or recede from its edge, 
which can then sometimes be seen to be studded with tiny perforate 
tubercles; the incrustation often envelops the ocecium, leaving only 
the aperture distinguishable. Among the tubes may be sometimes 
found miniature avicularia. 

Oewcra globose, free edge curved inwards. 

Avicularia vicarious, rare except along the edge of zoaria, wide at 
the head, and tapering towards the foot, close to which they are 
spanned by a slender bar, of which, as a rule, the broken ends alone 
are preserved as a slight constriction of the outline; the broad 
elliptical aperture is coterminous with the walls in the lower part, 
but in the upper part is surrounded by an internal shelf. 

Found in the zone of J. cor-anguinum at Gravesend (abundantly) 
and in Hants. 


PsEUDOSTEGA, gen. noy. 


Diagnosis—A genus of Membraniporide in which a secondary 
zocecial layer is formed over and arising out of a layer of ordinary 
Membraniporidan zocecia. 

This genus seems to be analogous among the Membraniporide to 
Steginopora among the Cribrilinide. The secondary layer apparently 
arises from the walls of the primary layer, and if so the essential 


260 R. I. Brydone—New Chalk Polyzoa, ete. 


difference between Pseudostega and Membranipora coralliformis is little 
more than one of degree. 


PsgupostrGa Canriana, nov. Pl. XXI, Figs. 6 and 7. 


Zoarium adherent. “sas 

Zoecia in the lower layer fairly large; length of area *3 mm., 
breadth *2 to -22mm.; in the upper layer they have only vaguely 
defined outlines and are very variable in minute details, but are very 
uniform in general structure ; they run in very straight and regular 
alternating rows, in which, after the initial zocecium, all have a large 
area, with a stout denticle projecting into it at the foot and directed 
slightly downwards, and, as a rule, a small curved indentation opposite 
to it at the head, possibly representing the aperture of an immersed 
ocecium; across the area stretches a broad bar, shaped like a very 
shallow V pointing downwards, which divides the area into two 
compartments, of which the lower is the smaller and is reduced by 
the point of the V and the marginal denticle to the shape of an eight 
lying on its side; at the foot the area is overlooked by two tubular 
prominences on the marginal wall separating it from the area of the 
preceding zocecium; these might naturally be taken to represent two 
avicularia of the preceding zocecium uniformly present in the lower 
layer, but I cannot find any traces of paired avicularia being regularly 
present there, the nearest approach lying in the tiny paired slits 
which can be seen at the head of some of the zocecia of the lower 
layer in Fig. 7, a figure of the only specimen in which the lower layer 
is exposed except at the very edge of the zoarium. The initial 
zocecilum of a row has the point of the V directed upwards and 
a denticle projecting from one side of the upper compartment; the 
lower compartment is much‘reduced and irregular in shape, and there 
is a single tubular prominence at the foot. This general system is 
much obscured by crowding in the early stages of the zoarium, but is 
remarkably regular in the later stages. 

Rare in the I. cor-anguinum zone at Gravesend and Chislehurst. 
Reptescharipora rustica, D’Orbigny, by its general appearance should 
be closely related to this species, but as Canu! makes it a Steginopora 
it must be assumed to have a Cribriline lower layer. 


EXPLANATION OF PLATE XXI. 
(All figures x 123 diam.) 

1. Membranipora Woodwardi, zone of Act. quadratus, Hants. 
», 2. Ditto, zone of Act. guadratus, Hants. Lighted to show up the interior of 

the zocecia. 
3. Ditto, zone of IW. cor-anguinum, Gravesend. 
», 4. M. coralliformis, zone of I. cor-anguinwm, Gravesend. 

5. Ditto, zone of M. cor-anguinum, Gravesend. From the tip of a large 

branching zoarium. 
», 6. Pseudostega Cantiana, zone of W. cor-anguinum, Gravesend. 
5, 7. Ditto, zone of M. cor-anguinum, Gravesend. Lower layer in focus, upper 

layer rather out of focus. 


1 Bull. Soc. Géol. France, 1900, p. 456. 


(Zo be continued.) 


Grou. Mac. 1910. Prarze X XI. 


e 
fi» * 


° 0 5 me 
er i >. we 
‘6 fet 4." 
(ep) 


R. M. Brydone, Photo. Bemrose, Collo. 


Baron Francis Nopesa—On Titanosaurus. 261 


TV.—Own tae Systematic Postrion or tHE Upper Creracreous 
Dinosaur ZTTANOSAURUS. 


By Baron Francis Norvcsa. 


EING prevented by other work from continuing at present my 
work on the Danian (Laramie) Dinosaurs of Transylvania, 
I wish briefly to draw attention to the fact that the Upper Cretaceous 
Titanosaurus, as known from the Montagne Noire in France and from 
the Cretaceous formation of Argentina, and perhaps also from East 
Africa (as already pointed out by Fraas), has nothing to do with the 
Sauropoda, but belongs to the Trachodontid Orthopods, as proved by 
the abundant Transylvanian material at my disposal. 

Without attempting to enter at present into the question of generic 
identity of the American, African, and European Upper Cretaceous 
Titanosaurs, I wish to point out that the Montagne Noire and the 
Transylvanian Reptiles are generically identical and must be known 
as Telmatosaurus, the name Z?tanosaurus being only applicable to the 
English Wealden Sauropod described in 1887 in the Quarterly 
Journal of the Geological Society. The striking survival of 
a Sauropod so late as the Danian may therefore be questioned, and 
the time-table in that most interesting recent paper ‘‘ Distribution 
and Range of Dinosaurs’’, by Professor R. 8. Lull, must therefore be 
modified accordingly. 

The Zelmatosaurus, to the tail of which the ‘ Z7tanosaurus vertebre’ 
belong (as proved by Transylvanian undescribed material), is a heavily 
built Trachodontid animal, with a straight Stegosaur-like femur 
(small fourth trochanter), a heavy and relatively strong humerus, 
nearly solid bones, and probably guadrupedal locomotion. Being the 
only Iguanodontid animal which we can suppose to have secondarily 
descended on its fore-legs (as Stegosaurus, etc., had done after passing 
a Scelidosaurus-like stage of evolution), Zelmatosaurus deserves special 
attention. Since Zelmatosaurus is accompanied in Transylvania by 
another Dinosaur (Mochlodon) which, according to its degree of 
specialization, would rather correspond with the Lower Cretaceous 
than with the Danian, and since the same is also true of the 
Telmatosaurus itself (see Sauvage’s remarks on Teématosaurus = 
Inimnosaurus in Rev. Crit. de Paleozoologie), the Dinosaurian fauna 
of Transylvania bears the same relation to the American Laramie 
fauna as the recent fauna of Australia to that of the recent fauna 
of the rest of the world. 


V.—Tue Geotocy or tHe Dotcettey Gotp-pert, Norte Wats. 
By Arruur R. AnpREw, M.S8c., F.G.S. 
(Concluded from the May Number, p- 221.) 

Lryn-y-groes Lode.—About 500 yards east of the Clogau lode, 
there is a parallel lode which has been worked for copper. Striking 
50° east of north, its outcrop may be traced for about 14 miles; its 
width is very variable. Chaleopyrite and pyrites and a little gold 
are present in the quartz. The lode is confined to the Vigra Beds, 


262 A. R. Andrew—The Dolgelley Grold-belt. 


and running with the beds, it is associated throughout its length with 
greenstone sills. 

Bryntirion Lode.—Kast of the Bryn-y-groes lode is another parallel 
lode, with, however, a strong dip to the south-east. Like the Bryn-y- 
groes lode it is poorly mineralized, and has been worked but little. 
It is confined throughout its length of three-quarters of a mile to the 
Vigra Beds, and it is but seldom associated with the intrusive 
ereenstones. 

Garth-gell Lode.—At its northern end this lode crosses the junction 
of the Afon Cwm-Mynach and the Nant-Cesailgwm, and from there it 
has been traced 200 yards to the south. Its strike is 25° east of 
north, and its dip vertical. It traverses the Vigra Beds all the way, 
and is associated with small greenstone sills and dykes. Throughout 
its length its width is very variable. In many places it has clay 
selvages along its walls, but these are not constant. The quartz 
of the vein is hard, white, and often drusy; pyrites and chalcopyrite 
are the most frequent minerals, and with them also are found blende, 
some galena, muscovite, and chlorite. In 1900, 26 tons of quartz were 
milled for 5 ounces of gold. 

Maes-tryfer Lode.—This is an unimportant vein which crosses the 
line of the Garthgell lode close to the junction of the Cwm-Mynach 
and Cesailgwm streams. Different from all the lodes already described, 
its strike is no longer north-easterly, but 30° south of east. It courses 
through the Vigra Beds, and is confined to very near their junction 
with the Clogau Slates. Little work has been done on the lode, and 
its characters are not known. 

Cambrian Lode.—800 yards above the point where the Afon Cwm- 
Mynach enters the estuary, the outcrop of a quartz lode is seen in 
the stream. It courses in a north-east and south-west direction 
(65° east of north) and can be continuously traced for about half a mile. 
It is vertical throughout its length; its walls are well defined, and in 
places have selvages of clay, 2 or 3 inches thick. The vein is poorly 
mineralized, the chief minerals which do occur being galena, chalcopyrite, 
and blende, for the first of which the lode was once worked. ‘The lode 
crosses the Vigra Beds of the Maentwrog Series. 

The Voel Group of Lodes.—About the year 1860 there were several 
companies mining different portions of the lodes of this group, each 
mine being known by a distinctive name, Princess Alice, Prince of 
Wales, Glan-y-morfa, and Moel-Ispri. Later (1900-4), these lodes 
were worked by the Voel Company. There are three separate 
parallel lodes on the property with numerous small stringers. The 
strike of the lodes is north-easterly, changing from 70° east of north 
on top of Foel Ispri, to 50° east of north near the turnpike road. The 
most southerly of the parallel veins (that nearest to the estuary) has 
been opened up in several places, and has a shaft extending below sea- 
level. The lode is from 1 to 3 feet wide, with clearly defined walls. 
The quartz contains a large amount of blende, along with some 
chalcopyrite, pyrites, and pyrrhotite. 

The intermediate lode of the three cannot be clearly seen; it is 
opened up by a few cross-cuts into the side of the hill, but these are 
no longer accessible. The uppermost and most northerly of the Voel 


A. R. Andrew—The Dolgelley Gold-beit. 263 


lodes dips usually to the south, but in places towards the north the 
lode is seldom less than 3 feet in width, often much more. Leaders 
and stringers are frequent, but otherwise the walls are well defined. 
The blende in this lode is abundant; galena and chalcopyrite also 
occur. The Moel-Ispri Mine (the Voel C lode) mined 66 tons of 
quartz for 88 ounces of gold, while the Prince of Wales Mine (the 
Yoel A lode) has mined 20 tons of quartz for 63 ounces of gold, The 
outcrop of the Voel C lode may be traced for about 1 mile; at its 
western end it strikes 70° east of north; towards the east it strikes 
more and more northerly, finally becoming 40° east of north. 

The two most southerly lodes of the Voel group occur in the Pen 
Rhos Beds; the most northerly runs along in the Vigra Beds for most 
of its observed length, but finally at its eastern extremity enters the 
Pen Rhos Beds. Greenstones occur frequently along the course of the 
veins, and the latter are most clearly defined in the neighbourhood 
of an igneous intrusion. 

Cesailgwm or Wnion Lode.—This lode is well exposed on the slopes 
of the hill east of Cesailgwm-mawr, about 14 miles up the stream 
which enters the Mawddach estuary near Borthwnog. Thence it 
may be traced at intervals for a distance of two-thirds of a mile to the 
west, and for a distance of about 2 miles to the east. Its general 
strike is 60° east of north, its dip never varies very much from the 
vertical. Its walls are well defined and consist of the Clogau and 
the Vigra Beds, near whose contact the lode always lies. Intrusive 
rocks occur at intervals along the course of the lode. The lode is 
usually 2 to 4 feet wide, often dwindling down, however, to mere 
veinlets. The vein is not heavily mineralized, but blende, galena, 
and chalcopyrite are found. In the years 1893-4 this lode produced 
36 ounces of gold from 61 tons of stone. 

In the Cesailgwm Valley, there is a lode parallel to and north of the 
Cesailgwm lode, which has been worked by the Borth Valley Gold 
Mining Company. Where opened up the lode formation is about 
4 feet wide; it has a banded structure, being made up of 2 feet of 
poorly mineralized quartz, and a varying thickness, up to 2 feet, of 
mingled quartz and crushed country rock. Few mineral sulphides 
are to be seen; gold can be got by crushing and panning. This lode 
yielded 27 ounces of gold in 1906. 

Blaen-y-cwm Group.—To the north of Blaen-y-cwm, near the head- 
waters of the Afon Wnion, there are numerous outcrops of small 
lodes, none of which extend far in strike. There are five lodes of this 
nature, all occurring in the Clogau Beds, though some extend from 
there into the Vigra Beds. ‘Two of these lodes strike 60° east of north ; 
two strike 15° south of east; one strikes 15° east of north. 

All the veins of this group are similar to each other in formation 
and contents. Their width ranges from 3 feet downwards. The 
walls of the vein are poorly defined and usually there is no selvage of 
clay. The intrusive greenstones are seldom seen in association with 
this group. The lode matter contains a large admixture of shaly 
material derived from the walls; the quartz contains galena, blende, 
arsenopyrite and pyrites. 

Cefn Coch Lode. —Next to the St. David’s—Clogau and the 


264 A. R. Andrew—The Dolgelley Gold-belt. 


Gwyn-fynydd lodes, this is the most important lode in the Dolgelley 
belt. On the slopes of Cefn Coch Hill, and to the north-east, it strikes 
45° east of north; to the south-west the strike becomes more northerly 
(25° east of north) for about half a mile; then on the slopes of Foel-ddu 
the lode regains its original strike; the total traceable outcrop 
amounts to about 2 miles. : 

Through the greater part of its length, the lode runs along the 
contact of the Clogau Slates and the Gamlan Shales. The topmost 
bed of the Gamlan group is here a coarse-grained quartzose grit, and 
at times the lode is represented by a series of stringers ramifying 
through this grit. Westward over the shoulder of the Cefn Coch 
Hill, the lode lies mostly in the Gamlan green shales and grits. 
Greenstone sills occur at intervals along the course of the lode and 
form one or both walls. This lode has been cited by earlier writers, 
e.g. Ramsay (12-15), as an instance of a vein forming the continuation 
of a greenstone dyke, but I have not been able to see anything more 
unusual than the pinching out of the lode close to a greenstone sill, 
The Cefn Coch lode branches frequently and is accompanied by 
parallel veins. The dip of the lode is towards the north-west, so that 
it very soon becomes confined to the Gamlan Beds below the surface. 
Its width varies from 6 inches up to 3 or 4 feet, occasionally swelling 
out into massive blebs of quartz, 10 to 12 feet thick. No clay 
selvage is present in the lode. 

The quartz of the lode is not well mineralized, though the parts 
already worked out probably contained a much larger proportion of 
mineral than those now exposed. The most usual minerals in the 
quartz are blende and galena, and there are also chalcopyrite, pyrites, 
zincite, and gold. An analysis of the gold from this lode gaye the 
following result: gold, 76°40 per cent.; silver, 22°70 per cent. 
Between the years 1863 and 1908, though the work has been of 
a most intermittent character, 2310 tons of quartz have produced 
1193 ounces of gold. 

Cae-mawr Lode.—This lode is seen on the hills on the western 
bank of the Mawddach near its confluence with the Afon-wen. The 
lode has little extent in strike; it strikes 15° south of east, and dips 
to the south at an inclination of 40° to the vertical. It intersects the 
Pen Rhos Beds of the Maentwrog, where its walls are clearly defined ; 
the lode is wide, from 8 to 15 feet across. The metallic mineral 
contained in the quartz of the lode is of small amount and consists of 
chalcopyrite alone. In 1891 development work on this lode produced 
10 tons of quartz for a return of 1 ounce of gold. 

Dol-y-clochydd Lode.—Opposite the Precipice Walk, on the crags that 
overhang the Dolgelley-Trawsfynydd road, outcrops of white quartz 
have been opened up by a cross-cut. The lode can be traced 
satisfactorily only for the extent of the greenstone sill in which the 
cross-cut is driven, but a few isolated outcrops probably mark 
a continuation along the line of lode beyond the sill. The quartz of 
the lode contains some chalcopyrite; its strike is 45° east of north. 
The lode and its accompanying greenstone sill lie among the Pen Rhos 
Beds, while the isolated quartz outcrops range up into the lower part 
of the Ffestiniog group. 


A. R. Andrew—The Dolgelley Gold-belt. 265 


Glasdir Lode.—This lode has been worked extensively for copper, 
and like so many of the other copper veins of the district, it has been 
found to contain gold in addition. The lode is situated on the hills 
on the eastern bank of the Mawddach below its confluence with the 
Afon-wen. The lode is confined to the lower part of the Ffestiniog 
Flags, and its extension in strike is apparently hmited. At the main 
workings the lode courses in a north-east direction, but its whole 
observed length of outcrop is not more than 100 yards. At the west 
end the lode appears to pinch quite out, and at this point a thin 
quartz-vein, running north and south, cuts across it; this vein has 
been worked a little, but is very barren. West of the quartz-vein, 
and running parallel to it, a large wide cross-course or fracture cuts 
the line of the main lode, and has smashed up the rocks for quite 
80 yards; to the west of this, the main lode is lost. 

The main lode is usually vertical, and its dip, though variable, 
is always great. It differs from all the other veins of the country in 
the almost entire absence of quartz. A good section is seen where 
the main cross-cut is driven to intersect the lode. Looking north- 
east, we see—(1) on the right, a fault-plane about 1 foot wide in 
which the country rock is much broken up and comminuted to pug 
and clay; (2) about 20 feet of green flags and shales, bent about, 
distorted, and slickensided. These flags and shales are impregnated 
with chalcopyrite to such an extent that they have been mined for 
some years for copper; the average tenor of the lode at this level is 
about 1 per cent. of copper, while in the deeper levels it rises and is 
said to approach 2 per cent. Blebs of quartz, usually white and 
poorly mineralized, occur throughout the impregnated flags, but they 
have no definite arrangement. In places the width of the impregnated 
zone or lode is as much as 50 feet; it has been opened up consider- 
ably in depth, but very little work has been done along the strike. 

The deposit has been formed by cupriferous solutions, rising through 
the fissure on the south-east side of the lode, passing thence into the 
flags, and there depositing part of their copper contents. It will be 
remembered that the flags are bent and crushed about, so that they 
readily allow the passage of mineral solutions, and the diminution of 
pressure in them would probably facilitate the deposition of the 
minerals held in solution. The almost total absence of quartz is the 
unique feature of this lode. Besides chalcopyrite, the only metallic 
minerals I noticed in the lode were pyrites, bornite, and erubescite. 
In 1900 this lode produced 1993 ounces of gold. The copper con- 
centrates generally assay about 1 ounce of gold to the ton. 

Ffridd-goch Lode.—High up on the eastern bank of the Afon-wen, 
more than a mile above its confluence with the Mawddach, the Ffridd- 
goch lode strikes 5° east of north, and dips steeply (70°) to the 
eastward. It can be traced for about 1200 yards; it is confined 
throughout to the lower parts of the Ffestiniog Flags. At its southern 
end the lode runs along and through several greenstone sills, but 
further north the latter die out. At places the lode is accompanied 
by one or more parallel lodes. Where it has been opened up it is 
well defined, and commonly 3 feet in width. The quartz is poorly 
mineralized, pyrites is the most usual metallic mineral, a little 


266 A. R. Andrew—The Dolgelley Gold-beilt. 


chalcopyrite and pyrite being also present. Gold was obtained from 
this lode during the period 1896-1902, 109 tons of quartz being 
crushed for 1053 ounces of gold. 

Ceunant-hyli Lodes.—The Ffridd-goch lode is crossed by the line of 
the Ceunant-hyll lodes, a set of two or three minor veins on which 
a small amount of development work has been done. Like the Ffridd- 
goch lodes these occur in the lower part of the Ffestiniog Flags, 
and are associated with large intrusions of a coarse-grained greenstone, 
which is in places amygdaloidal. The largest lode strikes 5° south of 
east, and can be seen for about 500 yards along the strike; its width 
is from 18 to 24 inches. There is also another lode, striking 65° south 
of east, and dipping much more steeply. The vein matter of these 
lodes is similar, and consists of crumbly pyritous quartz, containing 
a large amount of tale and chlorite, and a little chalcopyrite; gold 
also has been found here. 

Dol-y-frwynog Lodes.—On the western bank of the Afon-wen, 
directly opposite the Ceunant-hyll lodes, is the southern extremity of 
the Dol-y-frwynog lodes. The main lode of these strikes 25° east of 
north, and has a course of at least 900 yards; it is accompanied by 
several parallel veins of variable extension in strike, the dip of all 
being approximately vertical. At the largest cross-cut there are five 
parallel lodes, ranging from 1 to 6 feet in thickness. To the north 
another lode has been worked to a great extent ; the strike is 35° east 
of north, and gold was here associated with chalcopyrite and pyrites. 
The rocks traversed by these lodes are the Pen Rhos Beds of the 
Maentwrog. Greenstones occur along the course of the lodes, and 
have their ferro-magnesian constituent largely converted to tale and 
chlorite. 

Cefn-deuddwr Lodes.—At the junction of the Afon Eden with the 
Mawddach, there are two parallel lodes striking 15° south of east, 
and dipping towards the north at an angle varying from 55° to 80°. 
They can be traced for only a short distance, along which they lie 
in the Vigra Beds of the Maentwrog, and cross in their course several 
greenstone sills. Chalcopyrite occurs in the quartz, galena and gold 
also occur in small quantities. 

Tyddyn-Gwladys Lode.—About a mile above the Mawddach-Eden 
confluence, on the road to the Gwyn-fynydd Mine, several old levels 
and cross-cuts open up the T'yddyn-Gwladys lode; this strikes about 
55° east of north, and dips from 60° to 80° towards the north-west. 
The outcrop of the lode lies in the Clogau or Menevian black slates, 
and passes through many sills of intrusive greenstone. In the places 
where the lode is now exposed, the quartz is white and poorly 
mineralized; the dominant metallic mineral is galena, for which, and 
the silver contained therein, the lode was mined. Other minerals 
seen in the lode-matter are blende, chalcopyrite, arsenopyrite, and 
pyrites. Gold has also been obtained from this lode, 7 ounces having 
been got in 1889. 

Cwm-heisian Lode.—On the opposite bank of the Mawddach from the 
Tyddyn-Gwladys Mine, is the Cwm-heisian or Cwm-eisen lode, which 
strikes 10° south of east, and dips towards the north, from 70° up to 
practically a vertical position. The lode outcrop is much obscured 


A, R. Andrew—The Dolgeliey Gold-belt. 267 


by glacial drift; to the west it lies in the Vigra Beds, and towards 
the east in the Pen Rhos Beds. Very little greenstone is to be seen 
along the course of the vein. The levels by which the lode was 
opened have now fallen in; where the lode outcrops, the quartz is 
white and opaque, with very little mineral. Specimens from this 
lode are to be seen in the Museum of Practical Geology, Jermyn 
Street, and of these Maclaren has said (38, p. 453): ‘‘The invariable 
associate. of the gold is zinc-blende, the latter being sometimes con- 
temporaneous and sometimes prior in point of deposition; galena and 
pyrites also occur, and indeed the veins were originally worked as 
a silver-lead mine.” The total reported output of this mine from 
1860 to 1905 has been 123 ounces of gold from 50 tons of quartz. It is 
stated also that in the early days this mine gave two large returns, 
ageregating 318 ounces of gold from 4574 tons of stone, but there 
are no figures to support this statement. 

Gwyn-fynydd Lode.—On the southern flanks of the Moel Gwyn- 
fynydd, about half a mile north of the junction of the Afon Gain and 
the Mawddach, several disused levels and shafts mark the outcrop of 
the Gwyn-fynydd lode. Like the majority of the lodes of this district, 
it is found along with parallel companion lodes, as many as twenty of 
these having been passed through in the cross-cut which opens up the 
mine; one of these companion lodes is in places 20 feet thick, and is 
known as the Chidlaw lode. The strike of the Gwyn-fynydd vein is 
about 70° east of north, and the dip is towards the north, never flatter 
than 70°. The outcrop can be traced for a distance of about 14 miles; 
at its western end it cuts across the top of the Barmouth Grits, then 
through the whole of the Gamlan into the Clogau Beds. Here the out- 
crop is thrown to the south by the Afon Gain fault, which courses down 
from the north. The lode then continues through the Clogau Beds 
into the Vigra Beds, in which it terminates against the Gwyn-fynydd 
fault, on the eastern side of which it has not been picked up. The 
lode in its course cuts through sills of greenstone, but these are not 
numerous. The thickness of the lode is variable: in the parts where 
it has been worked (i.e. in the Clogau Beds) it is from 3 to 25 feet in 
width, to the west and to the east it may often be as thin as 2 or 8 feet. 
Often the lode includes large bodies of slate and shale. The lode 
material consists of very white quartz, with great patches of galena, 
pyrites, and chalcopyrite in finely granular aggregates. In addition 
to the above, orpiment, pyromorphite, and mimetite (40, p. 693), 
arsenopyrite and blende (38, p. 452) are said to occur. Gold has 
only been found at those places where the vein crosses the Clogau 
black beds. Where it occurs it is often in a very finely divided 
state ; sometimes, however, it is massive and arranged as in irregular 
veinlets. During the period 1864-1907 this mine has produced 
36,116 ounces of gold from 96,569 tons of stone; during certain 
periods (especially 1888-92) it has furnished practically all the gold 
output of Merionethshire. 


SUMMARY OF THE AvnriFerous VEINS. 


It is to be remarked that in the Dolgelley Gold-belt not a single 
auriferous vein is found in any formation lower than the Clogau 


268 A. R. Andrew—The Dolgelley Grold-belt. 


or Menevian black slates. Some of the auriferous veins may extend 
into the. Gamlan Beds, but they appear to lose their auriferous 
character. Again, no vein is known to be auriferous above the lower 
part of the Ffestiniog Flags. The only formations in this Dolgelley 
Gold-belt which are intersected by auriferous quartz-veins are the 
Menevian (Clogau), the Maentwrog (Vigra and Pen Rhos), and a small 
part of the Ffestiniog—a total thickness of about 3600 feet. 

Throughout the gold-belt of Dolgelley the igneous intrusions 

greenstones) are for the most part not of large extent; it is only the 
larger ones that are noted on the geological maps which accompany this 
paper; they are, however, very numerous, and the auriferous veins 
are found close to them, often, if not always, forming part of the wall 
or walls. The Dolgelley lodes appear to have no gossan; underground 
their characters appear to be similar to those they possess at the 
outcrop. 

Reviewing the facts concerning the occurrence of the auriferous 
veins of Merionethshire, we may say: 

(1) That the usual strike of the auriferous lodes is north-east and 
south-west, in some cases diverging to east and west, in others to north 
and south; the bulk, however, strike north-east and south-west. 

(2) That there is no difference in mineral contents between the 
veins that range north-east and south-west and those that range east 
and west, or north and south. 

(3) That auriferous veins are not found below the Clogau or 
Menevian Beds. 

(4) That they occur only in black carbonaceous slates or shales, 
rich in pyrites. 

(5) That they are associated always more or less intimately with 
igneous intrusions. 

(6) That the lode material consists usually of quartz, often with 
calcite and impregnated country rock. In one case (Glasdir) the 
whole material of the lode consists of ‘these impregnated shales 
and flags. 

(7) That the most usual minerals associated with the gold are 
blende (sphalerite), chalcopyrite, galena, and pyrites. 

(8) That the gold is usually coarse, granular or aggregated, and 
seldom shows crystalline faces; rarely it occurs finely disseminated 
through the quartz. 

(9) That the distribution of the gold in the lodes is very capricious, 
and is not known to follow any regular law, though it appears most 
possible that it may be regulated by the fractures or cross-courses 
which intersect the lodes. Whatever the cause of the rich pockets, 
on them depends the future success of the mines, and until the law 
regulating their distribution is discovered, the mining of these lodes 
will always entail even more uncertainty than that which is usually 
associated with any gold-mining. It seems that it might be advisable, 
in the case of those mines now at work, to investigate as far as 
possible the influence that these cross-courses have on the distribution 
of the gold in the lodes. 

(10) That in the upper portions of these lodes there is no conspicuous 
belt of ordinary weathering, though as work on these lodes has not 


A. R. Andrew—The Dolgelley Gold-belt. 269 


proceeded to any great depth it is possible that the whole of the lodes 
so far mined may be in part enriched by secondary enrichment. 


GENESIS OF THE AURIFEROUS VEINS. 


The general idea of the genesis of auriferous veins is that they 
were filled by waters carrying gold and other minerals in solution ; 
these waters rose from below through fissures and deposited their 
metallic contents in those fissures owing to— 

(1) Decrease of temperature, which caused the solutions to become 
supersaturated and to deposit part of their contained minerals. 

(2) Decrease of pressure which acted similarly. 

(3) Reactions between the ascending waters and other solutions 
which entered the fissure along its course; a common precipitant for 
gold, which is also a common substance underground, is ferrous sulphate, 
and another is carbonaceous matter. 

(4) Reactions between the ascending waters and the solid material 
forming the walls of the lodes. 

Subsequently the lode so formed was subjected to a process of 
secondary enrichment, which, by solution and re-deposition of the 
gold content, caused a relative enrichment of the upper portions of 
the lode. 

Applying these general principles to the Dolgelley Gold-belt, there 
is to be remarked, on the one hand the total absence below the Clogau 
horizon of any black or carbonaceous bed, and on the other the 
total absence of any auriferous vein below that horizon. It appears 
that the solutions rising in fissures through the Lower Cambrian rocks 
were affected only by decrease of temperature and pressure, which 
were not, however, sufficient to cause any important deposition of 
gold. At the horizon of the Clogau Beds, however, solutions entered 
from the wall-rocks, containing ferrous sulphate and organic matter, 
in both of which the Clogau Beds are rich; interactions between the 
two solutions caused a precipitation of the gold. As the solutions 
passed upwards into the Maentwrog Beds, more and similar solutions 
would enter, and gold would be deposited there also. The greatest. 
amount of gold, however, would probably be deposited at the Clogaw 
horizon. This theory tallies with what we know of the occurrence 
of the gold in the field; far and away the bulk of the gold has. 
been obtained from the two lodes whose outcrops are in the black 
Clogau Beds. 

The most ready channels for solutions to enter would be through 
cross-fractures, and at these points we might expect to find greater 
deposition of the gold. So far, we only know of this having occurred 
im one instance at the St. David’s lode and one at the Panorama lode; 
but the paucity of examples may be due to deficiency of observation, 
for no one appears to have been on the look out for cross-courses and 
their possible effects. 

The almost constant association of the auriferous beds with intrusive 
greenstones means only, I think, that the heat of the magma gave the 
percolating waters during the period of the intrusion a greater chemical 
activity, and rendered them capable of dissolving out and holding in 
solution more substances with which they came in contact. 


270 A. R. Andrew—The Dolgelley Gold-belt. 


Secondary enrichment is in this district only of slight importance ; 
there is an absence of oxidized minerals in the outcrops, and there is an 
absence of the minerals which are usually considered to be characteristic 
of a zone of secondary enrichment. 

‘The association of minerals found in the lodes, and especially the 
pyrrhotite, suggests deep-seated lode formations, i.e. lodes formed 
at some considerable distance below the then existing land surface, 
but which, owing to denudation, are nearer to the land surface 
existing at the present day. 

With regard to the existence of small traces of gold in the country 
rock of these lodes, I was unable to determine whether such existed or 
not. Maclaren (38, p. 508) had made some assays, and had found 
minute traces (‘0007 grain of gold per ton) in some of the country 
rocks; but it is not clear whether such gold, even if it could 
satisfactorily be proved to exist in the country rock, had not really 
been introduced into the country rock from the veins. 

From this account of the gold veins of the Dolgelley Gold-belt, it 
may be inferred as most probable that as the mines working on lodes 
that outcrop in the black Clogau Beds work down below that horizon 
they will leave behind them the rich pockets of gold. Although it is 
possible that a cross-course conveying gold precipitants may cause the 
formation of a pocket at this lower depth, still it is not very likely. 
Those mines which operate on lodes outcropping in the Vigra and 
higher beds will, if they work down to the Clogau horizon, improve 
their chances of striking rich pockets of gold; it is possible, however, 
that they would not survive to work down to that depth. Where the 
lodes cut across the Clogau Beds it is most probable that the rich 
pockets are dependent for their position on the occurrences of cross- 
courses. 

In examining the lodes underground it is difficult to acquire 
information regarding the associations of the richer pockets. In 
most cases it is no longer possible to examine the places where the 
richer pockets were found. Really, such examination could only 
satisfactorily be carried out by one who constantly visits the working 
faces and notes down all particulars which may have a possible 
bearing on the occurrence of these greatly coveted bonanzas. In an 
American mine this would be done by the mine geologist, whose 
special duty it is to collect geological data regarding the ore-deposits ; 
but as such an official does not exist in English mines we can only 
hope that a substitute may be found in one of the regular mine 
officials, whose duty causes him to inspect the working faces day 
by day, and whose love of research prompts him to record all the 
geological facts that come within his observation. 

Professor Lapworth, of Birmingham University, has aided me 
greatly in the preparation of this paper: he has spent many days 
with me in the field; he has shown me through the sequence of 
beds; he has given me the benefit of his experience in the laboratory 
and office work connected with this paper: for all of these aids 
and also for his never varying encouragement, I am truly grateful. 
To the officials of the St. David’s Gold Mining Company, and 
especially to Mr. Nicholls, the general manager, I am very much 


A. R. Andrew—The Dolgeilley Gold-belt. 271 


indebted for opportunities of visiting the lodes underground, and also 


for 


a vast amount of information regarding the occurrence of those 


richer pockets of gold, which they are always in the hope of finding. 


Ov He Oo NO 


23. (1866) J. Pranr & E. Witiramson. Ibid., vol. vy, pp. 2 
. (1867) T. Berr. Gror. Mac., Vol. IV, pp. 294, 493, 536; Vol. V, p. 5. 


BIBLIOGRAPHY. 


(1836) Sepewick & Muxcutson. Rep. Brit. Assoe., 1835, p. 59. 

(1841) Sepewier. Proc. Geol. Soe., vol. iii, p. 545. 

(1843) Sepewick. Ibid., vol. iv, p. 213. 

(1847) Sepewicr. Quart. Journ. Geol. Soc., vol. iii, p. 133. 

(1852) Sepewrex. Ibid., vol. viii, p. 146. 

(1854) Sepewrek. 4 Synopsis of the British Paleozoic Rocks, with a 
Systematie Description of the British Paleozoic Fossils in the Museum 
(of the University of Cambridge), by Prof. MeCoy, p. 20. 

(1839) Murcutson. The Silurian System. 

(1842) Murcuison. Anniversary Address: Proc. Geol. Soc., vol. iii, p. 641. 

(1854) Murcsison. Siluria, 1st ed. 

(1858) Murcuison. Ibid., 2nd ed. 


. (1854) H.M. Geological Survey Map of Brifain, Nos. 135, 149, Merioneth. 


(1866) Ramsay. Memoir of the Geological Survey, vol. iii, pp. 19, ete., with 
Appendix by J. W. Salter. 

(1880) Ramsay. Ibid., 2nd ed., vol. iii. 

(1853) Ramsay. Quart. Journ. Geol. Soc., vol. ix, p. 161. 


. (1854) Ramsay. Ibid., vol. x, p. 242. 


(1846) D. SHarps. Ibid., vol. ii, p. 304; also Svo, London. 


. (1848) J. B. Juxses & A. R. Setwyn. Ibid., vol. iv, p. 300. 
. (1853) J. Hopxrms. Ibid., vol. ix, p. 61. 
. (1853) J. W. Satrer. Rep. Brit. Assoc., 1852, p. 56. 


(1865) J. W. Satrer. Notes explanatory of a Map of the Faults of the 
Dolgetiey District, Svo, Manchester. 


. (1866) J. Pranr. Quart. Journ. Geol. Soe., vol. xxii, p. 505. 


—— J. Puant. Trans. Manchester Geol. Soc., vol. v, p. 76. 
20-8. 


(1868) D. Forses. Ibid., Vol. V, p. 224. 


. (1872) D. Forsers: Siluria, Appendix, p. 547. 


(1867) D. Forses. Phil. Mag., ser. tv, vol. xxxiv, p. 338. 


. (1888) J.J. H. Teatn. British Petrography, p. 215, pl. x, fig. 1. 


(1860) T. A. Reapwiy. Gold Discoveries in Merionethshire, Svo, Manchester. 
(1862) T. A. Reapwix. List of Gold Ores from Merioneth, Svo, Manchester. 


. (1888) T. A. Reapwin. Gold in Wales, 8vo, London. 


—— T. A. Reapwix. Mining Journal, vol. xl (1870), pp. 699, 918, 940, 
982; vol. xlv (1875), pp. 678, S44, 929, 1042, 1096, 1137, 1208, 1236, 
1292, 1319, 1347, 1404, 1431; vol. xlvi (1876), pp. 20, 48, 75, 126, 152, 
180, 283, 261, 289, 318, 345, 374, 401; vol. 1 (1880), pp. 135, 761, S48, 
877, 904, 931, 988. 

(1881) T. A. Reapwix. Gold in Britain, 8vo, London. 

(1862) T. A. Reapwin. Rep. Brit. Assoc., Trans. Sect., p. 87. 


: fis L. H. L. Hupparr. Trans. Inst. Min. and Metallurgy. 


1844) Dean. Rep. Brit. Assoc., Trans. Sect., p. 56. 


2 ae 


- (1844) Roserts. ining Journal, p. 383 ; also (1845) pp. 6, 37, 38. 
. (1902) J. M. Mactaren. Trans. Inst. Min. Engineers, vol. xxv, p. 435. 
. (1903) Boorx. Cassier’s Magazine, vol. xxiii, No. 4. 


Dr. Ure. Dictionary of Arts, ete., 7th ed., vol. ii, p. 692. 
(1849) Mining Journal, p. 94. 
(1865) Ibid., p. 134. 


. (1860) Ibid., p. 670. 
. (1875) Tbid., p. 1236. . 
. (1865) Roperr Hunt. Mineral Statistics, p. 36. 


J. A. Puruures. Treatise on Ore Deposits, p. 204. 


272 L. Richardson—Inferior Oolite Vertebrates. 


VI.—On rue SrrarieraPuicaL Disrrisution or tHE Lyrerror-OoLiTE 
VERTEBRATES OF THE CorreswotD Hitts anp tHE Bara—Dovrtine 
Disrricr. 

By L. Ricuarpson, F.R.S.E., F.G.S. 
ERTEBRATE- REMAINS are by no means abundant in the 
Inferior-Oolite rocks of the Cotteswold Hills and Bath—Doulting 

District. Mr. H. B. Woodward, F.R.S., has written— 

‘¢ The Inferior Oolite Series has yielded a rich and varied Invertebrate fauna, but 
the remains of Saurians and Fishes are very rare. 

“‘The Reptilia that have been found include Megalosawrus and Stencosawrus, and 
the Fishes are represented by Hybodus, Strophodus, etc.” 

At the end of the work from which the above quotation is taken is 
a list of the vertebrate-remains which had been collected up to that 
year, namely, 1894.’ 

In 1904 I gave a list of the vertebrate-remains which had been 
recorded from the Cheltenham district,” and, except for the record for 
vertebrae and bones of ? Zehthyosaurus from Leckhampton and Sudeley 
Hills (on the authority of James Buckman & H. E. Strickland, and 
the more precise stratigraphical location of certain of the other 
recorded remains), my list was the same as that given in the 
Geological Survey Memoir mentioned above. 

The following list is by no means a lengthy one, but as it embodies 
the results of quite ten years’ collecting on my own part, and 
considerably longer on Mr. Charles Upton’s part, it will be at once 
understood that vertebrate-remains are by no means common in the 
Inferior-Oolite rocks. 


List oF VERTEBRATE- REMAINS FROM THE INFERIOR - OOLITE OF THE 
CotrEeswotp Hits anp Batua-Dovrtine District. 
(Those distinguished by an asterisk are in the Author's collection.) 
REPTILIA. 
Dinosauria. 
Megalosaurus Bucklandt, von Meyer. Lower Freestone (Hemera 
Murchisone). Aalenian. 


CRrocoDIrLtA. 


Stencosaurus megistorhynchus (Deslongchamps). ‘‘ Fragment of 
maxillary rostrum, showing three dental alveoli,” ‘ Gryphite- 
Grit” (Sonninie). Bajocian. 

Say R. Lydekker, Cat. Fossil Reptilia in the Brit. Mus., pt. 1, 1888, 
p. 116. 

*? Stencosaurus sp. Reptilian jaw probably of Stencosaurus. Witchellia- 

Grit (Witchellie). Bajocian. .Cold Comfort, near Cheltenham. 


IcHTHYOPTERYGIA. 
Ichthyosauria. 
? Ichthyosaurus sp. Vertebree, etc. ?Bajocian. Leckhampton and 
Sudeley Hills. 
(Vide James Buckman & H. E. Strickland, 2nd ed. of Murchison’s 
Outline of the Geology of the Neighbourhood of Cheltenham, p. 80.) 


1 “ The Jurassic Rocks of Britain—The Lower Oolitic Rocks of England (Yorkshire 
excepted)’: Mem. Geol. Sury., vol. iv (1894), pp. 519-22. 
2 A Handbook of the Geology of Cheltenham (1904), p. 230. 


LT. Richardson—Inferior Oolite Vertebrates. 273 


SAUROPTERYGIA. 
Plesiosaur va. 


*? Plesiosaurus sp. Tooth. Lower Zrigonia-Grit (discite). Bajocian. 
Frith Quarry, near Stroud. 
Professor §. H. Reynolds and Dr. C. W. Andrews both state that this tooth 
is ‘* Plesiosaurian in type’’. 
*? Pliosaurus sp. Two teeth. Top of Lower Zrigonia-Grit or bottom 
of Buckmani-Grit (diseite). Bajocian. 
Professor §. H. Reynolds states that these teeth ‘‘are exactly lke 
Pliosaurian teeth in the British Museum ’’—an identification confirmed by 
Dr. C. W. Andrews. 
A piece of bone 6 inches long was obtained from the Gryphite-Grit 
of the west side of the Slad Valley, Stroud, by Mr. C. Upton. 


PISCES. 
ELASMOBBANCHEI. 
Selachit. 


Asteracanthus. See Strophodus. 

Strophodus. General Note.—The teeth called Strophodus include two 
species: one in which the crown is flat (S. magnus, Ag.), and the 
other in which it is considerably elevated, and the tooth itself 
long and narrow (S. tenuis, Ag.). Satisfactory figures of these 
species will be found in the Catalogue of the Fossil Fishes in 
the British Museum, pt. i (1889), pl. xv, figs. 2, 3, and 4-8. 
The teeth which have been named S. retcculatus are now definitely 
known to belong to Asteracanthus ornatissimus, Ag., and are very 
differently ornamented and keeled. 

S. magnus, Agassiz. Teeth. Aalenian, Bajocian, and Bathonian. 

Recorps: Clypeus-Grit or Doulting Beds. — *Harford Bridge (near 
Bourton-on-the- Water) ; *Birdlip Hill; *Slad Valley (near Stroud); *Rod- 
borough Hill; *Soundborough Farm (near Andoversford) ; Quarry seven-eighths 
of a mile east of Paulton Church (near Radstock, Somerset) ; and *Doulting. 

Upper Zrigonia-Grit.—*Holwell (near Frome: ‘‘ Acanthothyris-spinosa- ° 
Bed”’) ; and *Maes Knoll, Dundry (near Bristol: ‘‘ Conglomerate-Bed”’). 

Notgrove Freestone.—*Belas Knap, near Winchcombe. 

Buckmani-Grit.—*Tuffley’s Quarry, near the Air-Balloon Inn, between 
Cheltenham and Birdlip. 

Base of Pea-Grit or top of Lower Limestone.—* Huddingknoll Hill, near 
Painswick. 

S. tenuis, Agassiz. Teeth. Bajocian and Bathonian. 


Recorps: Clypeus-Grit or Doulting Beds. —*Doulting; *Foss-Way 
Quarry, near Radstock. 

Upper Trigonia-Grit.—* Wellow, near Radstock (‘‘ Conglomerate-Bed ’’). 

Gryphite-Grit.—*Kimsbury Castle (teste C. Upton). 


HoocePHatti. 


Myriacanthus sp. Fragments of palatine teeth. Identified by Dr. A. 
Smith Woodward. Inferior-Oolite. Cleeve Hill, near Cheltenham. 


Remains of this genus of Chimeroid fish have not been recorded before from 
the Middle Jurassic: ouly from the Lias and Kimmeridgian (vide Dr. A. 
Smith Woodward, Quart. Journ. Geol. Soc., vol. lxii, 1906, pp. 1-4, and pl. i; 
Brit. Mus. Cat. Fossil Fishes, pt. ii, 1891, p. 48). Unfortunately the 
fragments from Cleeve Hill were not found in sitz. 


DECADE V.—VOL. VII.—NO. VI. 18 


274 A. R. Horwood—Transition-bed and Crinoidal Limestone. 


? Fish-teeth._—Mr. Charles Upton found amongst the micro-organisms of the 
Upper Coral-Bed ( Zrwel/ei-hemera) a number of minute teeth not unlike those from 
the Rheetic which are generally called ‘‘Sawrichthys acuminatus’’, only much smaller. 
Also he obtained a minute round Lepidotus-like tooth. 

? Fish-remains in the Scissum-Beds.—Brodie, writing of the beds at Leckhampton 
Hill (Quart. Journ. Geol. Soc., vol. vii, 1851, pp. 208-12), which are now called the 
Scissum-Beds, observes: ‘‘ Bones, scales, Coprolites and teeth of Fish are dispersed 
throughout the mass, and may be most readily distinguished on the surface.” 
At Crickley Hill the Scissum-Beds reveal on their weathered surfaces, mixed up 
with the sand-grains and shell-debris, innumerable black particles, which prove to be 
minute phosphatic bodies. ‘hese may be the objects to which Brodie refers, but it 
is impossible to identify them. 


Tue Inrerior-OoLire VERIEBRATES OF NO VALUE FOR THE PURPOSES 
OF MINUTE ZONING. 


From the above list it will be observed that the fish-teeth called 
Strophodus are commonest in the Top-Beds (and especially in the 
Clypeus-Grit) ; the Reptilian remains in the ‘ Intervening-Beds” ; 
while the Freestone Series (except at Huddingknoll, near Painswick, 
where Strophodus teeth are very common) contains very few verte- 
brate-remains indeed. The Upper Coral-Bed has yielded a few, but 
unfortunately indeterminate, teeth, although probably piscine. 

Except, then, that the flat Strophodus teeth predominate in the 
Top-Beds, the little acuminate ? fish-teeth in the Upper Coral-Bed, 
and the reptilian remains in the Intervening-Beds, the Inferior-Oolite 
vertebrates afford little assistance in subdividing the series and are 
useless for minute zoning purposes. 


VII.—Nore oN A FURTHER EXTENSION OF THE ‘ TRANSITION-BED’ AND 
Crinormat Limestone Banp In THE Mippue Liss or LEercestERsHIReE. 


By A. R. Horwoop, Leicester Museum. s 


LLUSION has been made in a previous paper’ to the crinoidal 
limestone band and Transition-bed at Billesdon Coplow, and to 

the existence of the former at Tilton Hill near Lowesby Station. At 
the latter place, though the Transition-bed is not exposed in situ, the 
position of the crinoidal limestone bed (after making full allowance 
for Drift deposits), is low enough, with beds normally horizontal or 
with a slight easterly dip, to adduce without any doubt the extension 
of the Transition-bed above it at this point. Thus the crinoidal 
limestone band had been traced at three points —Tilton (vide 
Wilson, ibid.),? Billesdon Coplow, Tilton Hill—in the southern portion 
of the exposed area of the Rock-bed in Leicestershire, up to the time 
when the second paper, contributed by the author dealing with this 
bed in Leicestershire, was written. That is to say, it had only been 
found in the southern series of bold escarpments or spurs into which 
the district is divided. For the Twyford brook, running more or less 
west and east, divides the two series to which reference is directly 
made into a northern and a southern series, or if we include the 
Belvoir, Stathern, Eastwell, Holwell, and Waltham tract still more to 
the north, into three, with a central tract north of the Twyford brook. 


1 Geol. Mag., 1910, p. 177; 1907, p. 462. 
* Op. cit., 1886, p. 296 et seqq. 


A. R. Horwood—Transition-bed and Crinoidat Limestone. 275 


Thus the southern portion which is free from Drift forms a series of 
winding sinuous escarpments right away from the Coplow to the 
south at Neville Holt, Hallaton, Medbourne, broken here and there by 
valleys now partially filled with Drift, or eroded by streams. And 
it has, furthermore, been lifted up by the Tilton—Loddington fault, so 
that some portion is now considerably out of its original position to 
the west. 

North of the Twyford brook the Marlstone in this central tract 
commences to form a bold feature to the west at Burrough-on-the-Hill, 
and in a less degree at Thorpe Satchville—but it forms a more 
continuous range of hills to the north-east of Burrough, where it 
constitutes the backbone of the ridge and connecting spurs, all classic 
hunting-ground, which stretch from Somerby, Pickwell, Knossington 
to Ranksborough and Whissendine—whilst near Owston it bends 
round to join the Tilton mass to the south. But except at Burrough 
Hill and a few other points the Rock-bed is greatly obscured by 
Drift, so that sections are few and far between. This, then, may 
be termed the central tract. 

In turn the most northerly Leicestershire massif is separated from 
the central tract by a line somewhat to the north of, but more or less 
parallel with, the Saxby and Bourne line from west to east, and 
extending from Holwell, Eastwell, Waltham, right up to Belvoir. 
It is connected by the Harby Hills, striking northwards from Long 
Clawson to Stathern, in the far north of the county. 

It is at Burrough-on-the-Hill, a place noted for its fine Roman 
encampment, which was earlier too probably a Celtic stronghold (and 
where now the Spring Parliamentary Steeplechases are yearly held), 
that the new discovery of the crinoidal limestone band has been made 
by the writer since the first paper (Gzox. Mae., April, 1910, p. 177) 
was in hand. The discovery is the more important as it relates to the 
central portion of the Marlstone outcrop, separated from the southern 
by a considerable distance. 

Though I had searched carefully for indications of this very 
characteristic bed (band 4 at Wildbore’s Lodge, Robin-a-Tiptoes, 
near Tilton’) at Burrough-on-the-Hill, I had until recently failed to 
find any indication of it. Except for an old trial-hole and obscure 
exposures, or slips covered with talus, no good section really existed 
on this extensive and well-known hill.* But in looking over some 
débris fallen from the higher ground on the northern extremity of the 
ridge, I discovered a curiously attenuated and modified form of the 
bed. This consisted of a thin sandy ferruginous rock with rounded 
and occasionally angular pebbles or inclusions of green and brown 
rock (chiefly Marlstone) and a few joints of crinoids. Evidently this 
was a conglomerate or brecciated conglomerate which represented the 
crinoidal limestone band at its western margin, at a period when that 
very constant, continuous stratum was being gradually elevated from 
the pelagic depths in which the normal highly calcareous band was 
being laid down. The marginal portion of this band lying in 

1 Vide J. W. Judd, ‘‘Geology of Rutland, etc.’?: Mem. Geol. Surv., 1875, 


p- 68. This bed may possibly be band 2 at Billesdon Brickyard (ibid., p. 69). 
* Since previous visits a small quarry has been opened, but in lower beds. 


276 A. R. Horwood—Transition-bed and Crinoidal Limestone. 


a synclinal trough would naturally first be exposed to waves and littoral 
conditions generally, and whilst retaining something of its original 
character (as shown by the scattered crinoid fragments) would also 
include pieces of sediment derived from littoral sources, and receive 
later littoral detritus; and if above water or near sea-level, rolled 
fragments would be mixed up with the pelagic matter. 

The fossils, indeed, found in the sandy ferruginous mass were 
those of beds lower down, e.g. Pecten lunularis, Lima pectinoides, 
Belemnites, etc. Whilst admitting that this rock, not being found in 
situ, might possibly represent our bed C at Billesdon Coplow, we 
consider at present it represents a higher series; but however that 
may be, subsequent discovery, stimulated by this find, is amply 
sufficient to support the correlation advanced later in this paper. 

The discovery of this abnormal rock was, in fact, a clue in itself, 
and though not found in situ indicated the close proximity of 
a similar or more normal band. Nor was I disappointed in the quest, 
for slightly higher up, after finding a loose slab of crinoidal limestone, 
of a browner colour than usual, in a small covert, a shallow overgrown 
excavation flanking a hedge-row revealed actual traces of the real 
crinoidal limestone band in situ. Here again, however, the deposit 
was also abnormal, for instead of constituting a single thick well- 
marked stratum it was split up into two beds divided by 10 inches of 
sandy ferruginous rock, with a conjoint thickness of 3 to 4 inches. 

We have thus evidence of the further extension of the crinoidal 
limestone band from the southern area to the northern or the central 
portion, indicated by an exceptional but highly interesting and 
instructive rock. It may be that this band has assumed the character 
of the thinner band (bed C) in the Billesdon Coplow section,’ where 
it is broken up and irregular, in which case it would indicate a zone 
just below the bed B, or crinoidal limestone band horizon, if 
identical; but, apart from their different lithological composition, 
differing as they do in purity of contents, the Burrough crinoidal 
band is regular in extent, though attenuated. It dips at an angle of 
somewhat more than 10° to the south-east (just at this point), and 
may thus represent just the western margin of the Middle Liassic 
sea. The conglomeratic band, whether equivalent to bed B or C at 
the Coplow, is an example of shore conditions, and laid down to the 
west, being now displaced by earlier quarrying and weathering. 

In thus establishing the original continuity of the crinoidal lme- 
stone band between the central and southern Marlstone tracts in 
Leicestershire we may, furthermore, venture to predict the existence 
of the ‘ Transition-bed’ at the same locality, for the crinoidal band is 
sufficiently below the top of the hill to allow this, as at Tilton Hill, 
being quite 5 feet below the surface on the higher ground. So that 
though paleontological evidence, which alone is conclusive, is not 
here forthcoming, owing to the character of the section, yet strati- 
graphic evidence is undoubtedly in favour of its existence. 

The section, in so far as it is possible to indicate its thickness, is as 
follows :— 


1 Trans. Northants Nat. Hist. Soc., 1907, p. 108. 


A. R. Horwood—Transition-bed and Crinoidal Limestone. 277 


ft. in. 
A. Broken ferruginous marly rock, sandy and much weathered. Probably 
representing ‘ ‘Transition-bed’ (bed A at Billesdon Coplow) : Se mG 
B. Thickly bedded sandy ferruginous rock with a seam of crinoidal lime- 
stone parted by 10 inches of sandy rock (bed B at Billesdon Coplow) 2 0 
Blue, green, or brown marly ferruginous, laminated beds, with 
Belemnites, Pecten, Tercbratula, Rhynchonella, base not seen ony) een 
(2?) Bed C, Billesdon Coplow. eehEN) 
6 0 
In so far, then, as Leicestershire is concerned the existence of the 
Transition-bed may be postulated in both the southern and the central 
tracts, whilst up to the present, though I have made search for it, it 
has not been met with in the northern tract. But less hopeful of 
finding it at Burrough as I was when it turned up at Tilton Hill, 
after its discovery at Billesdon Coplow, its present further extension 
may be said to give additional reason for prophesying its discovery in 
the future in the more extensive but less easily accessible district 
between Belvoir and Melton, where there is a thick covering of Drift. 


Notr.—Since my previous paper on the occurrence of aragonite in the 
Middle Lias of Leicestershire was published I find that aragonite has 
been discovered in the Cheltenham district at Churchdown,! Gloucs. 
This in no way minimizes, I think, the interest attaching to my own 
observations, which devolved rather upon the mode of formation and 
composition of different parts of the Marlstone, and their physical 
history, rather than upon the bare record of the occurrence of this 
mineral itself, which is not uncommon as a shell-substance in all 
districts. And whilst the Leicestershire specimens are not the first 
recorded examples they add to the significance of the occurrence 
elsewhere by suggesting a definite horizon at which the general 
temperature of the waters of the sea in the Marlstone epoch were 
much warmer over a wide area, than either above or below, and not 
merely locally at one spot. The extension of range, moreover, of 
aragonite in the Middle Lias, as a mineral pure and simple, is in itself 
assuredly of some interest. 

I haye to make a correction in the same paper, having inadvertently 
written Barnstone for Wartnaby in reference to the occurrence of 
stria on the surface of the rock-bed. In the recently published 
Survey memoir on the Melton Mowbray district, a photograph and 
diagram of the quarry where these striae were noticed are given 
(plate iii and fig. 6). 

In the same memoir (p. 40) it is stated that no specimens of 
Amaltheus margaritatus have actually been found in the district 
surveyed (Sheet 142). It may be worth while mentioning here 
that this zone-fossil was found by me in 1908 in that area, not in 
situ but doubtless derived from a local source, on the mineral line 
which runs down from White Lodge to the Great Northern Railway 
south of Harby and Stathern Station. It occurred below the rock-bed 
outcrop and within the area of the margaritatus shales, so was doubt- 
less derived from them at this place. 


1 F. Smithe, Proc. Cotteswold Club, vol. vi, p. 349; Mitchell, Geology of Stroud, 
ps 17. 


278 A. L. Leach—Glacial Drift near Amroth. 


VITI.—On « Gractat Drirr ar Marros, nEaR AmnorH. 
By A. L. Lzacu. 
NE mile and a half east of Amroth a small valley which opens on 
the coast of Carmarthen Bay at Marros shows drift deposits of 
much interest. The valley itself is noteworthy. Like several others 
in the vicinity it is deeply cut in comparison with its width; the 
gradient of the valley sides is as high as 1 in 2, and the depth below 
the bordering hills is not less than 300 feet. The stream, which now 
drains the valley, rises on Marros Mountain, barely 2 miles from 
the shore, and flows down the main dip-slope of the Coal-measures, 
which here are greatly disturbed by folds and faults. 

The pre-Glacial origin of the valley is suggested by its depth, and 
fully confirmed by the nature of the drifts, which cover the floor and 
are well displayed on the shore, where the sea has cut into these 
deposits and formed a vertical section, 200 feet long, extending from 
side to side of the valley. Other sections are shown in the banks of 
the stream, which by excavating a new channel through the drifts 
has cut down to the pre-Glacial rock-floor. But although the stream 
has reached the rock it does not. flow along the lowest part of the 
pre-Glacial valley ; it has cut a new channel in the rock several feet 
above the base of the drifts and, as will be shown later, its post- 
Glacial erosion may be estimated. The chief interest of this small 
valley arises from the exceptional clearness of the relation between 
the drifts and the valley-floor. The larger valleys to the west of 
Marros are choked with recent alluvial deposits, and their mouths 
are blocked by sand-dunes and storm-beaches, which, except in one 
case, completely hide any glacial deposits that may be present. 

The Marros Valley is excavated in shales and grits of the Coal- 
measures. A small anticlinal fold rises under the glacial gravel in 
the mouth of the valley, and probably a fault is concealed by the thick 
drift deposit. 


oad 


1 
' 
5 
! 

<f 

2 
' 


~s 
ers 


eS 


Section of the Drifts at Marros, near Amroth: a, newer stony loam; 3, older stony 
loam; ¢, glacial gravel. Length of section 200 feet. The thickness of the 
drifts is exaggerated. 

The drift section shows at the bottom a stony loam composed of 
decayed local rocks, in which are embedded angular blocks and slabs 
derived from the slope of grits and shales against which it rests. 
Close to the west side of the valley this deposit is nearly 20 feet thick, 
but after it passes under the glacial gravel its base, being hidden by 
a storm-beach, cannot be seen, and the thickness shown in the cliff 
does not exceed 3 or 4 feet. The glacial gravel rests upon an wneven 
surface of this stony loam, except on the eastern side, where it rests 


A. L. Leach—Glacial Drift near Amroth. 279 


on the solid rock. It is a very coarse gravel, containing brown and red 
sandstones and red marls (Old Red Sandstone), brown grits and shales, 
yellow grits and quartzites (Coal-measures and Millstone Grit), with 
large well-worn boulders of quartz and pale quartzite. The stones 
are closely packed in a small gravel composed of similar materials. 
The thickness of the gravel is from 4 to 6 feet, its base resting on an 
uneven surface of the stony loam described above. The source of some 
of the rocks is indicated above. All the Old Red Sandstone debris is 
derived from rocks not only outside the basin of the Marros stream 
but separated from it by a deep valley in the Carboniferous Limestone: 
the quartz boulders are also erratics, and an igneous boulder which 
was found in situ in the gravel appears to be derived from some of 
the intrusive igneous rocks of Pembrokeshire, at least 12 or 15 
miles to the north. A considerable proportion of this gravel has 
therefore been derived from beyond the present basin of the stream, 
and some of it has apparently come from the north-western side of 
the broad valley of the Taf. The glacial origin of the gravel is thus 
proved, since no agent except moving ice seems adequate to transport 
material into the Marros Valley over one, if not over two watersheds. 
At its western edge the glacial gravel is overlain by stony loam similar 
to that which underlies the gravel. 

In their formation these drifts belong to two classes; the bottom 
stony loam appears to be a talus of purely local origin accumulated 
against the slopes of the valley during severe climatic conditions and 
subsequently spread out over the floor of the valley. The glacial 
gravel is probably not a true moraine, but water-deposited glacial 
debris formed as an ‘outwash gravel’, the material being derived 
from moraines higher up the valley or on the hills to the north. 
There is no lack of evidence of the glaciation of the district. Glacial 
drifts and numerous erratic boulders occur on these hills and extend 
many miles to the south-west in Pembrokeshire.! On “the ridge 
south-east of Marros” Dr. Strahan? noted a well-glaciated block of 
Millstone Grit. 

The formation of the Marros Valley gravel as an ‘ outwash’ 
deposited by glacial torrents will explain the non-occurrence of 
striated and scratched stones which were vainly sought for in the 
deposit. Any such striations would have been obliterated during the 
formation of the gravel by torrential streams. 

A passing reference was made to the present channel of the stream 
which has cut down through the drifts to the rock, but, in the mouth 
of the valley at least, has not reached the lowest part of the pre- 
glacial floor. Deflected to the east side by the drift, it has cut 
a shallow channel along the rock slope on that side, several feet 
probably above the old stream-course, and now falls to the beach in 
a small cascade. The depth of this new channel, about 3 feet, 
may be taken as an indication of the erosion accomplished by the 
stream mainly in the post-Glacial period. 


1 R. H. Chandler, ‘‘ On some Unrecorded Erratic Boulders in South Pembroke- 


shire’’: Grou. Mac., Dec. V, Vol. VI, No. 589, May, 1909. 
2 Sum. Prog. Geol. Survey, 1908. 


280 Notices of Memoirs—Glaciation in the United States. 


INO'TIGES OF) WE MeLrRSs 


pee 
Tae Sournernmosr GraciaTion In THE Unirep Srares. By D. W. 
JOHNSON." 


N a recent number of Sczence? H. W. Fairbanks and E. P. Carey 
| report evidences of ‘‘ Glaciation in the San Bernardino Range, 
California’, in latitude about 34° 7’ N. Concerning this interesting 
discovery the writer says: ‘‘It has hitherto been assumed that the 
southernmost point of glaciation in the United States was in the 
Sierra Nevadas, nearly 200 miles to the north” (north of latitude 
36° N.). If their observations are correct they have found the most 
southern instance of satisfactory evidence of glaciation in this country, 
so far as I recall; but there are several records of glaciation farther 
south than the point in the Sierra Nevada referred to by them. Brief 
references to these may be of interest. 

Science for November 22, 1901,? contained a ‘‘ Note on the Extinct 
Glaciers of New Mexico and Arizona”, by George H. Stone, in which 
he reported evidences of glaciation in one of the Rocky Mountain 
Ranges ‘‘as far south in New Mexico as a point not far north of 
Santa Fé” (latitude about 35° 41’). Ina later paragraph we read— 

‘The farthest south and west I have found traces of extinct glaciers 
is at Prescott, Arizona. Around Prescott are numerous moraines. 
The highest part of the névé of this glacier could not have been much 
above 9000 feet. The central part of the glacier is approximately in 
N. lat. 34° 30’. The occurrence of an ancient glacier so far south as 
this was probably due to a very great snowfall owing to the proximity 
of the ocean . . . Probably there were then small glaciers in some 
of the cirques of northern exposure among the mountains directly 
south-east of Prescott.” 

R. D. Salisbury published an article on ‘‘Glacial Work in the 
Western Mountains in 1901”, in vol. ix of the Journal of Geology, 
1901. Beginning with p. 728 is a brief description of glacial features 
in the mountains near Santa Fé, between 35° 45’ and 36° North 
latitude. Some fifty cirques were found, and about eighty ponds and 
lakelets. One of the glaciers had a length of 7 miles. Moraines, 
strie, and roches moutonnées were observed. In 1902 I had an 
opportunity to visit this same region, and I entertain no doubt as 
to the ample proof of local glaciation in those mountains. 

In the Journal of Geology for 1905+ is a paper by Wallace W. 
Atwood on the ‘‘ Glaciation of San Francisco Mountain, Arizona”’. 
This writer describes and figures terminal and lateral moraines, and 
an outwash plain, and reports the occurrence of striated boulders and 
polished and grooved bedrock. I have briefly mentioned evidences of 
glaciation on this same peak, attributing a somewhat greater amount 
of erosive work to the glacier than is recognized by Atwood, and 
mentioning what I then believed to be a terminal moraine located 
near the mouth of a cirque.’ The latitude of San Francisco Mountain 
is about 35° 21’ N. . 

1 Reprinted from Science, n.s., vol. xxxi, No. 789, pp. 218-20, February 11, 1910. 

2 January 7, 1910. 3 Vol. xiv, p. 798. 4 Vol. xiii, p. 276. 

® Technology Quarterly, 1906, vol. xix, p. 410. 


Notices of Memoirs—Glaciation in the United States. 281 


F. J. H. Merrill reports in Science for July, 1906,* ‘‘ Evidences of 
Glaciation in Southern Arizona and Northern Sonora.” In the vicinity 
of Nogales, and elsewhere, were found deposits which he believed to 
be of glacial origin, while the surface had “the rolling topography 
and pitted surface of a moraine’’. Nogales is in latitude 31° 20’ N. 

The above references may be but a partial list of the published 
reports of glaciation south of the point in the Sierra Nevada referred 
to by Fairbanks and Carey; I have made no effort to prepare 
a complete list. Of these reports, the one on glaciation near Nogales 
is the most striking, because of the low latitude and low altitude 
in which the deposits are found. The evidence as reported does not 
appear sufficiently convincing, in view of the strong probabilities 
against the occurrence of glacial deposits in the region in question. 
Merrill’s descriptions suggest a landslide origin for the deposits which 
he took to be glacial. With reference to the glaciation of San 
Francisco Mountain I wish to add the following paragraphs. 

On my visit to San Francisco Mountain I ascended the volcano by 
the north-west slope, and I descended into the north-western part of 
the ‘crater’. JI was impressed with the cirque-like form of the 
depression, and came to the conclusion that the original crater had 
been destroyed by stream and glacial erosion, and that the encircling 
cliffs were to be regarded as cirque-walls rather than as crater-walls. 
The great central depression of the volcano consisted of several more 
or less distinct cirques uniting down-stream. Near the mouth of one 
of these was what I interpreted as a crescentic terminal moraine, 
rising 150 feet or more above the valley floor. But there were 
certain associated features which puzzled me at the time. Up-stream 
from the supposed moraine the floor of the cirque appeared to be 
deeply buried by an accumulation of rock débris which was generally 
as high as, and near the head of the cirque distinctly higher than, 
the morainal ridge. This débris was in places, especially near the 
marginal walls arranged in parallel ridges trending with the axis of 
the valley; and in the depressions between the ridges were patches of 
snow and some small ponds. Thus the moraine had a steep frontal 
slope, but at the back merged with the ridged rock débris, which rose 
to still higher levels. There were some depressions in the rock débris, 
25 to 40 feet deep, which I took to be ice-block holes. No bedrock 
was seen in the cirque floor. 

During the recent meeting of the Geological Society of America, 
Professor H. B. Patton, of Boulder, Colorado, exhibited some photo- 
graphs of the rock streams of Veta Mountain, Colorado. One of these 
photographs showed the high and steep front terminus of a rock 
stream, and resembled very closely the front slope of the supposed 
moraine in the San Francisco cirque. Others of his pictures showed 
the longitudinal parallel ridges which characterize some rock streams, 
with bands of snow lying in the hollows between the ridges, just as 
was the case in the San Francisco cirque at the time of my visit. 
If the concentric wave-like ridges pictured by Howe? were present 
in the San Francisco deposits, I did not notice them. 

Pviol-sxiv, p. 116. 

* «* Landslides of the San Juan Mountains ’’: U.S.G.S. Professional Paper, No.67. 


282 Reviews—Crystalline Structure and Chemical Constitution. 


I am inclined to believe that the features which puzzled me at the 
time of my visit may have been due to landslides or rock streams. 
This does not mean that the depression in which the features occur is 
not a glacial cirque, nor that the moraines reported by Atwood are 
not true moraines. It simply means that I am not wholly satisfied 
with the evidence of glaciation as reported by myself. It would seem 
that the possibility of a landslide of rock-stream origin for features 
apparently due to glaciation must be carefully considered, especially 
when glaciation in doubtful localities is involved. 


RAV LEws- 
pve) 

I.—Crysrattinr Srrucrure and Cnemican Constirution. — By 
A. E..H. Turron, D.Se., M.A. (Oxon.), F.R.S., A.R-C.Se. (onda): 
pp- vili204, with 54 figures in the text. London: Macmillan 
and Co., 1910. Price 5s. net. 


R. TUTTON’S reputation for crystallographical research stands so 
high that the announcement of a book from his pen on a subject 
of such primary importance as crystalline structure and chemical 
constitution cannot fail to awaken general interest among those 
interested in crystallography, but we fear that on realizing the true 
scope of the book many readers will feel considerable disappointment. 
Far from discussing the wide subject comprehended by the title of 
the book, Dr. Tutton confines himself entirely to a comparatively small 
section of it, and, moreover, to his own contributions to that section. 
Everyone may not have seen the prospectus relative to the series of 
science monographs of which this is the first volume, and may not be 
aware of the intention of the publishers that ‘‘ each volume will be 
unique, inasmuch as the author will describe chiefly his own con- 
tributions to the specific subject of scientific research with which 
it deals”: to prevent misunderstanding it is desirable that this 
restriction should appear on the title-page. This volume, at least, 
cannot pretend to be at all an adequate discussion of the subject with 
which it is supposed to deal. 

On the other hand, the book provides an admirable summary of the 
fine series of investigations upon which Dr. Tutton has for the past 
twenty years been engaged, and the reader may obtain a clear idea of 
the nature and results of the research without the labour of hunting 
up the original papers in the various periodicals in which they 
appeared. The most casual reader cannot fail to be struck with the 
pains taken to ensure that the apparatus and the crystals used in the 
investigations were of the most perfect quality obtainable, and with 
the indefatigability that has characterized the observational work. 
In the introductory pages the author, doubtless carried away by his 
enthusiasm, has depicted in unduly dark colours the state of the 
knowledge of isomorphism obtaining at the time he commenced his 
researches. The book is well printed, and its value is enhanced by 
several excellent illustrations, in one of which the author is seen in 
the act of grinding a crystal-section. 


Reviews—Dr. G. F. Matthew—The Little River Group. 288 


II.—Geronocy or rap Lirrne River Grove. 

(1) Tue Grorocican AcE or THE Litrte River Grovr. (2) Revision or 
THE Frora oF THE Lirrte River Group, No. Il. (8) RemarKasiE 
Forms or tHE Lirrne River Grove. By G. F. Marruew, 
Dese.; LD: ; 

N account of the discovery in this group of important and varied 

kinds of vegetable remains, its geological age is of much 
importance. This article is a brief statement of the geological 
evidence bearing on the age of the group. These are chiefly the 
relations to neighbouring formations which underlie or overlie 
the group, the amount of metamorphism it has undergone, and 
the lithological resemblance of the succession of beds to that of the 

Silurian strata in neighbouring districts. The conclusion is arrived 

at that the group is of Silurian age. There is a map showing the 

relations of the Little River Group to the adjoining strata. 

(2) In this paper is given an account of the type of Sir J. W. 
Dawson’s Dadoxylon Ouangondianum, and of two new Pteridosperms, 
one, Johannophyton, including Dawson’s Alethopteris discrepans and his 
Sporangites acuminatus (the latter considered as fruit bracts of the 
former): reasons are given why these should be considered parts of 
- one and the same plant; the fruit is shown to be a small oval seed. 
The other Pteridosperm is a small creeping plant with the foliage 
of Aniemites, and the fruit a small berry; it is named Ginkgophytun 
Leavittt on account of the resemblance in the form and venation of 
the leaves to those of the Ginkgo-tree. 

This paper treats also of the Psilophyta of the formation, as well as 
of some new species of Sphenophyllum and Whittleseya: the Psilophyta 
are not thought to be typical of the genus. Six plates of fossils 
accompany this paper. 

(8) This article treats of some animal forms and of tracts of 
Batrachians and Articulates of this group. A Zeaia and a new genus 
of Merostome, Belinuropsis, are fully treated of, also the wings of two 
large insects are described. The footprints are partly of Batrachian 
and partly of ‘Crustacean’ type; three genera of the former are 
described, and three species of the latter; the Batrachian footprints 
are much like those of Batrachians of the Coal-measures, the others 
are attributed to insects or Arachnids, and are in consecutive series of 
tracks of various sizes. 

A series of plates represent these ancient and interesting footmarks 
left on the sands of this old Silurian series of strata. 


I1J.—Armenia. 

N 1906 we called attention in these columns to Dr. Felix Oswald’s 
book on the Geology of Armenia. This was followed the next 
year by his Explanatory Notes to accompany a Geological Map of 
Armenia, and we have now before us his final conclusions on the 
geological structure of this area, published in Petermann’s Geo- 
graphischen Mitteilungen, 1910, under the title of ‘‘ Zur tektonischen 
Entwicklungsgeschichte des armenischen Hochlandes”. The present 
paper is accompanied by a map showing the Tertiary fault-lines as 
a series distinct from those of older date; and seven panoramic views 


284 Reports and Proceedings—Geological Society of London. 


of the Musch Plain, the Malaskert Plain, Lake Van, and the Bingo] 
group. As indicated by its title, Dr. Oswald’s new work is a purely 
tectonic one, and rounds off the story of the geology of a district 
which he has so lucidly and fully described. 


IAQ R ans) VAINYD 22 @CG Sth iNet. 


I.—GuotoetcaL Sociery oF Lonpon. 
April 18, 1910.—Professor W. W. Watts, Se.D., M.Sec., F.R.S., 
President, in the Chair. 

The following communications were read :— 

1. ‘The Voleano of Matavanu in Sava.’ By Tempest Anderson, 
MDL, DiSeu, Gas. 

Savaii is one of the German Samoan Islands in the Central Pacific 
Ocean. It is entirely volcanic, is formed of different varieties of basic 
lavas, and is for the most part fringed with coral reefs. 

The volcano of Matavanu was formed in 1905. The eruption was 
at first explosive, but since the first few weeks has been mainly 
efflusive and accompanied by the discharge of an enormous volume of 
very fiuid basic lava, which has run by a devious course of about 
10 miles to the sea, formed extensive fields of both slaggy and cindery 
lava (pahoehoe and aa), filled up a valley to a depth in some places of 
probably 400 feet, and devastated some of the most fertile land in the 
island. ‘The crater contains a lake, or rather river, of incandescent 
lava, so fluid that it beats in waves on the walls, rises in fountains of 
liquid basalt, and flows with the velocity of a cataract into a gulf or 
tunnel at one end of the crater. It then runs underground along 
a channel or channels in the new lava-field until it reaches the sea, 
into which it flows, and causes explosions attended with the discharge 
of showers of sand and fragments of hot lava, and the emission of vast 
clouds of steam. 

The many resemblances to, and few differences from, the voleano of 
Kilauea are discussed. 

2. ‘Notes on the Geology of the District around Llansawel 
(Carmarthenshire).” By Miss Helen Drew, M.A., and Miss Ida 
L. Slater, BA. (Communicated by Dr. J. E. Marr, F.R.S., F.G.S.) 

In this paper the authors deal with the stratigraphy and geological 
structure of a small area some 9 miles to the west of Llandovery, and 
to the north of Llandeilo. In a brief introduction the reasons for the 
selection of this region are mentioned, and the work of previous 
observers is touched upon. 

The rocks consist of a varied series of sediments, including a coarse 
conglomerate, grits, shales, and tough blue mudstones; cleavage is 
almost everywhere intense. 

The beds fall naturally into three divisions, as follows :— 


( ( C 3. Pengelli Shales (Gala fauna). 
C. Luansawet Group { C 2. Zone of Monograptus communis. 
C 1. Clyn March or cyphus Grits and Shales. 
( B 2. Llathige Shales and Mudstones. Zone of Meso- 
5: graptus modestus. 
| B 1. Penn-y-ddinas Grits and Shon Nicholas Conglomerat:. 
A. Brrtt Tew Grove. Beili Tew Grits and Shales. 


B. Caro Group 


Reports and Proceedings—Geological Society of London. 285. 


The stratigraphical relationships are seen most clearly in the highest 
group (C), which is therefore dealt with first. The beds here follow 
each other in perfectly regular succession, with a uniform strike of 
K. 30° N. The basal beds, with a fauna belonging to the zone of 
Monoyraptus cyphus, form a well-marked ridge across country, and 
Upper Birkhill and Gala Beds follow to the north-west. 

The second group (B) occupies a wide tract to the east of the 
Llansawel Group. The coarse basal deposits, and the characteristic 
shales and mudstones, are described from many localities. 

The lowest group (A) has its greatest development on the south of 
Llansawel. 

The structure in the eastern part of the district shows many points 
of interest, and is very much more complicated than in the west. 
The repeated outcrops of the conglomerate in the hilly region around 
Shon Nicholas are described in detail, and these give the clue to the 
structure. 

The paper concludes with a general summary and a brief comparison 
of this district with those of Rhayader and Pont Erwyd. 


Il.—Aprii 27, 1910.—Professor W. W. Watts, Sc.D., M.Sc., F.RB.S., 
President, in the Chair. 

The following communications were read :— 

1. “On the Evolution of Zaphrentis delanouet in Lower Carboni- 
ferous Times.”” By Robert George Carruthers, F.G.S. 

The small simple corals that belong to the gens of Zaphrentis 
delanouet are of common occurrence in the Lower Carboniferous rocks 
of Scotland. Their distribution is remarkably sporadic, but it is 
possible to collect over wide areas of which the stratigraphy is 
definitely known. A large number of specimens have been got 
together (some twelve hundred in all) from horizons scattered 
throughout the sequence. The ontogeny of these specimens has been 
investigated by means of serial transverse sections. 

The evolutionary changes observed aré confined to the disposition 
of the septa, which has influenced the shape of the cardinal fossula 
in a very marked manner. The external characters, and the spacing 
and curvature of both septa and tabule, remain unchanged. 

Zaphrentis delanouei is, typically, a Tournaisian species, and it has 
a wide fossula, expanded inwardly. When the gens first appears in 
the Scottish rocks (in the Cementstone Group of Liddesdale) 
4. delanouet is the predominant form, but is associated with a mutation 
(in Waagen’s sense) in which the fossula is parallel-sided. 

In the higher limestones of Lawston Linn another mutation 
appears, which, for reasons detailed in the paper, is regarded as 
a sport, or offshoot from the direct line of evolution. 

In the succeeding Lower Limestone Group the gens undergoes 
further modification. Adults of the two Cementstone species are 
extremely rare, and the predominant form has a fossula which 
narrows rapidly to the inner end ; in subordinate association a further 
mutation is also developed, in which the septa are short ‘and 
amplexoid. 

In the still higher horizons of the Upper Limestone Group the 


286 Reports and Proceedings—Geological Society of London. 


last-mentioned mutation becomes predominant, and persists up to the 
Millstone Grit, where the septa become more amplexoid. 

All these mutations, in neanic life, have characters seen in adults 
of the preceding form; tachygenesis is so marked that earlier 
ancestral traits are rarely seen. 

Mutational percentages are given for many localities in the 
Carboniferous Limestone Series of the Central Valley, together 
with an analysis of the data so obtained. 

Brief diagnoses of the four new species are appended to the paper, 
Eee with full locality-lists. 

2. ‘The Carboniferous Limestone South of the Craven Fault 
(Grassington—Hellifield District).”” By Albert Wilmore, B.Sc., F.G.S. 

As to the lithology of the beds, some are massive, coarsely stratified 
limestones, made up largely of crinoids, or corals, or shells (or 
mixtures of these); others are well-bedded, almost flaggy, black | 
limestones made up of finely comminuted matter, with abundant 
Foraminifera. There is every gradation between these extreme types. 
Variation in lithological character is lateral as well as vertical. 

The strata are much disturbed everywhere. A series of folds 
strike roughly north-east and south-west, and are somewhat complex. 
There is considerable repetition of beds, and thickness is not so great 
as at first appears. This bears on the interesting question of the 
comparison of beds north and south of the Craven Fault. 

The well-known knolls (‘reef-knolls’) are discussed. Their beds 
and those in the immediate neighbourhood are much disturbed, 
Irregular coarse bedding, folding, and normal long - continued 
weathering will explain most of their structural and other peculiarities. 
A typical knoll is dissected (Swinden); and it is seen to consist of 
folded, faulted, grey, coarsely-bedded limestone, with numerous great 
joints ‘and much evidence of internal ‘ weathering’. Comparison of 
these knolls is drawn with the corresponding hills in the dark well- 
bedded limestones. 

It is not easy to work out the exact zonal sequence, because of the 
disturbed character of the strata and the prevalence of glacial and 
fluvio-glacial drifts. The strata are apparently all Viséan (and the 
author does not think that there is anything lower than Middle or 
Upper 8). 

In some beds, and under some circumstances, fossils are exceedingly 
plentiful and easily procured. 

Some corals receive more especial notice, such as Caninia gigantea, 
Mich., which is distinctive of certain beds. Other species of Caninia 
are found. New or not well-known species of Zaphrentis are described. 
The author briefly discusses the relationships of the genera Caninia, 
Campophyllum, Calophyllum, Zaphrentis, and Amplecus. New (?) 
species of Lophophyllum are also described, and the generic characters 
of Lophophyllum are discussed. There is a remarkably localized 
distribution of some corals, and Syringopora is very common in certain 
of the beds. 

Suggestions are made as to the advisability of the disuse of some of 
the specific names. It is suggested that not more than four species 
of Carboniferous Syringopora need be retained. 


Grou. Mac. 1910. PLATE XOX 


The Rev. Prebendary Wm. Henry Ecrrton, M.A., F.G:S. 
a veteran Geologist (1811-1910). 


) 


Reports and Proceedings—Zoological Society of London. 287 


IIl.—Zootoctcat Socrery or Lonpon. 
May 3,1910.—Dr. A. Smith Woodward, F.R.S., Vice- President, in 
the Chair. 

Dr. A. Smith Woodward, F.R.S., communicated a paper by 
Dr. R. Broom, D.Sec., C.M.Z.S8., ‘‘On Tritylodon, and on the 
Relationships of the Multituberculata.’”? The author had re-examined 
the type and only known specimen of Zritylodon, and in one or two 
points came to different conclusions from Owen and Seeley. The ~ 
large flat piece of bone which forms the upper part of the snout, 
regarded by both Owen and Seeley as the frontal, was believed to be 
the upper part of the nasal. The supposed parietal was held to be 
the frontal. No distinct prefrontal could be made out; but there was 
believed to be a large distinct septomaxillary. The dental formula 
was believed to be 23 m’, instead of, as supposed by Owen, 2? m°. 

Gidley’s recent paper on Ptilodus was criticized at some length, and 
an endeavour made to controvert his conclusion that Péclodus is allied 
to the Diprotodont Marsupials. 

It was held that while the Multituberculates are doubtless very 
unlike the living degenerate Monotremes, they are more primitive 
than the Marsupials and not at all closely allied to them, and that 
till the evidence of their affinities is much greater than at present 
they may well be left as an independent order. 


(QS Oy YN IS8 SZe 
THE REV. WILLIAM HENRY BG ERO Na aVisAy Ge GES. 
Born NovempBer 13, 1811. Dizp Marcu 17, 1910. 
(PLATE XXII.) 


In the death of the Rev. W. H. Egerton the Geological Society has 
lost its oldest Fellow—one who had. been elected on June 13, 1832, 
and had been a Fellow for nearly seventy-eight years, a record 
doubtless unique in the history of scientific societies. Probably the 
longest previous record of a Fellow of the Geological Society was 
that of Sir Richard John Griffith, elected a Member in 1808. He 
died in September, 1878, in his ninety-fifth year, after being connected 
with the Society for seventy years. 

The fourth son of the Rev. Sir Philip Grey Egerton, ninth 
Baronet and Rector of Tarporley and Malpas in Cheshire, the 
Rev. W. H. Egerton was brother of the distinguished geologist 
Sir Philip de Malpas Grey Egerton (1806-81). He was educated 
at Brasenose College, Oxford, where he graduated in 1835, and was 
afterwards elected a Fellow of his College. 

Inspired by the teachings of Buckland, he early gave attention to 
geological subjects, and in 1833 a short communication by him ‘‘ On 
the Delta of Kander’? was read before the Geological Society and 
published in the Proceedings (vol. ii, p. 76). The River Kander, 
after a course parallel to the Lake of Thun, had formerly flowed 
into the Aar, but owing to inundations its waters were diverted 
about the year 1731 into the lake. The author described the delta 


288 Obituary—Rev. W. H. Egerton. 


since formed as extending about a mile along the shore of the lake 
and a quarter of a mile distant from it. 

In 1835 Mr. Egerton entered the Church, and was Curate at Stoke- 
upon-Trent 1836-9, Rector of Malpas 1840-5, Vicar of Ellesmere 
1845-6, and finally Rector of Whitchurch in Shropshire for sixty- 
two years, having retired only two years ago. Until the end he 
held a Prebendal Stall in Lichfield Cathedral. 

Murchison, in his Szlurian System (1839, p. 23), acknowledges 
assistance from the Rev. W. H. Egerton in determining the boundary 
of the Lias on the borders of Cheshire and Shropshire. In 1844 
Professor Edward Forbes read before the Geological Society a ‘‘ Report 
on the Collection of Fossils from Southern India’’, presented by 
C. J. Kaye and the Rev. W. H. Egerton, who had personally obtained 
an extensive series of specimens from Pondicherry, Verdachellum, and 
Trichinopoli (Proc. Geol. Soc., iv, p. 325). 

While preserving a collection of fossils and retaining interest 
in local geology, the Rev. W. H. Egerton had devoted his energies 
to clerical and educational work. ‘‘ As Church dignitary, scholar, 
and educationist he was a Rector of whom to be proud, and Whit- 
church was fortunate indeed to have had the benefit of his spiritual 
guidance and goodly counsel for so many decades. Between him 
and his parishioners there always existed a mutual esteem, and the 
bond grew stronger with the passing years.” ' 


MISCHILUILANHOUS. 


—__—_@-—_—@_. 


Sepewick Prize Essay.—The subject for the essay for the year 
1918 is ‘“‘On the Unconformities in the Mesozoic Strata of the 
Neighbourhood of Cambridge and their Significance”’. The essays are 
to be sent in to the Registrary on or before October 1, 1912. The 
prize is open to all graduates of the University who shall have resided 
sixty days during the twelve months preceding the day on or before 
which the essays must be sent in.—Morning Post, April 1, 1910. 


Tur Mrneran Waters oF Essex.—A full and interesting ‘‘ History 
of the Mineral Waters and Medicinal Springs of Essex” has been 
contributed by Mr. Miller Christy and Miss May Thresh to the Essex 
Naturalist (vol. xv, pts. vii and viii, issued 1910). The subject is 
of more geological than medical importance, as the authors state, 
‘‘Speaking generally, we may say that, with few exceptions, the 
reputed Essex Mineral Waters which we have analysed for the 
purpose of this investigation cannot be regarded as Mineral Waters 
at all. The few which may be rightly so classed owe such small 
medicinal properties as they possess almost entirely to the presence 
in them of magnesium sulphate (Epsom salts).” 


1 From the Chester Cowrant, March 23, 1910. 


Decade V.—Vol. VII.—No. VII. Price 2s. net. 


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ClO ae! IN oe SS 


I. Ox1GINAL ARTICLES. Page II. Reviews. Page 


Erosion and Deposition by the Indus. 
By Axruur Hitt, O.1.E., and 
even hig Hata, MEAL ER GiSs <2 


Some Observations on the Brighton 
Cliff. By Epwarp A. Martin, 

_ New Fossils from the Dufton Shales. 
; (Part III.) By F. R. Cowrzr 
qi Reep, M.A.,_ F.G.S. (Plates 
XXIII and XXIV.) Ei ee ee 


Wind-worn Pebbles in High - level 
Gravels. By Lronarp J. WI1Ls, 
M.A.,F.G.S. (Plate XXV.) ... 299 


| Upper Keuper Sandstones, East 
tf Nottinghamshire. By Bzrrnarp 

} 

i 


290 


SmirH, M.A., F.G.S. (Plate 
XXYVI and three Text-figures.)... 


A Chelonian from the Purbeck, 
Swanage. By D. M. 8. Warson, 
B.Se. (With two Text-figures.) . 311 


British Earthquakes, 1908-9. By 
Cuartzs Davison, Se.D., F.G.S. 315 


302 


LONDON: DULAU’ & CO., 


289 | 


Professor J. W. Gregory on Fossil 
Bryozoa from the Chalk eyall 


Professor A. C. Seward on Fossil © 
Plants ch asap eee eee Ra Oa 
| Memoirs of the Geological Survey : 
The South Wales Coal-field . 326 


Transvaal Geological Survey: Gold 
Mii esi a8 et Ge eee ... 828 
M. MeNeill on Colonsay ... ... ... 328 
G.W.Lamplugh, Presidential Address 329 
Brief Notices: Fossil Insects—Geo- 
logical Photographs — Iowa Geo- 
logical Survey — Surface Waters, 
United States 2 ERAS OE 
III. Rerorts anv ProceeEprnes. 


Geological Society of London— 


May 25, 1910 331 
IV. CorrEsPoNDENCE. 
Arthur Wade 334 


Rey. RB. Ashington Bullen— ae: 
J. B. Scrivenor ... ensonian- ingziy 


V ‘ARY. 


Professor R. 3 east a 7 ee O 

L 29 1910U 

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Begs to call the attention of Directors of Museums 
and Professors of Biology and Geology in Universities 
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Rare and Interesting Fossils. 


This interesting and attractive series will form a most 
valuable addition to any Museum of Zoology or 
Comparative Anatomy, and cannot fail to prove of 
the greatest interest alike to men of Science and to all 
Students of Natural History as well as to the general 
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specimens, when properly mounted and displayed in glass cases, 
with instructive labels to each, would form a substantial basis for 
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GHOLOGICAL MAGAZINE. 
NEW RSERIES: “DECADE Vo" VOLE Ville 
No. VOB eye 1910. 


Oe EGSEIN EASE, PAGE En @ rene S5 


I.—Erosion and Deposrrion BY THE INDUS. 
By Artuur Hixtz, C.1.E., Assistant Secretary P.W.D. Bombay. 


[Communicated by the Rev. E. Hill, M.A., F.G.8., The Rectory, Cockfield, 
Bury St. Edmunds. | 


‘67/T\HE Indus has been eroding severely on the right bank, about 
30 miles higher up than the erosion which I told you threatened 
the railway at Rohri on the left bank. The chord of the curve of the 
bank attacked was over 2} miles long, and the erosion at the apex 
would be as much as 100 feet a day: it amounted to 3400 feet in 
forty days. It has given us a good deal of trouble, as with a big 
breach here the water would travel 120 miles before it would be 
forced back to the river by the hills on the edge of the deltaic deposits, 
and loop embankments of great length had hastily to be constructed 
behind the portions of the flood-embankments threatened with erosion. 
We succeeded with two loops, but with the third had a breach in the 
weak new loop; the men have been able to keep it from spreading 
more than 700 feet wide, and have since got it nearly under control. 

‘Tf the bones of the famous geological mule had been on the river 
bank, they might have been dropped down to the 60 or 100 feet 
depth to which the river erodes, and have had half a mile of deposits 
put down alongside them, and between them and the bank of the 
river; for these channels in bends eroded are filled up again equally 
rapidly when the river cuts across the chord. So your mule might 
have had 60 feet depth over him, and the half-mile of new silt along- 
side him, in three months. The construction of a square mile of new 
deposits, 60 feet deep, in about two months time, is of almost annual 
occurrence locally on the Indus. These are, of course, not [pure ? | 
silt deposits ; they are merely the land at the side of the river rolled 
over, as in ploughing. 

‘*« Pure silt deposits occur, where the river overtops its natural bank, 
and in side-channels of the river where the exits are getting smaller 
than the upstream ends. In the latter case considerable depths, 
15 feet or so, of pure silt are deposited in a month or two. 

‘Most silt probably goes on to the sea. The average discharge of 
the Indus during 1906, from June to September inclusive, was 


400,000 cubic feet per second. . . . The maximum quantity of silt 
observed in suspension was 2797 grains weight per cubic foot of 
water. . . . I have not worked out the quantity of silt for the year, 


but clay weighs about 120 lbs. a cubic foot. . . .” 


DECADE V.—VOL. VII.—WNO. VII. 19 


290 E. A. Martin—Brighton Chff Formation. 


The above is extracted from a private letter of my brother’s, written 
September 15, 1909, in answer to some questions I had asked relating 
to the behaviour of rivers. It seems to me likely to interest others 
besides myself, and he has given me leave to make any use of it. 
I have printed it as written. 

The figures work out as follows :— 

The maximum quantity of silt observed in suspension gives a trifle 
less than 1 cubic foot of clay from 300 cubic feet of water. 

The discharge of water in the four above-named months is 4,216,320 
millions of cubic feet. 

If this contained the observed maximum of silt it would be sufficient 
to deposit a layer of 1 foot of clay over 503 square miles. 


II.—Some OxssEervations on THE Bricguton Crirr Formarron.! 
By Epwarp A. Martin, F.G.S. 


URING the past eighteen years I have made certain observations 
on the cliff formation on the east of Brighton and on the sections 
successively brought into view by repeated falls of the cliff. The 
chief item to be noted from -them is, that as the cliff wears back, the 
base-platform of chalk grows in height, that is, the old surface of 
the chalk dips towards the south. Also, that the layer of sand which 
Prestwich found above the chalk grew thinner and thinner, until it 
has now completely disappeared. At the same time the raised beach 
has grown in thickness from 13 feet to 12 feet. 

In 1890 the raised beach still remained about a foot and a half 
thick, as noted by Prestwich, with about 6 feet of sand beneath it. 
An illustration of the cliffs at this date has appeared in a little work 
called Amzdst Nature's Realms, and can be referred to there. An old 
groyne remained, but it was in a very damaged condition, and it was 
noticeable that the usual accumulation of beach on the western side 
had not taken place there. The groyne was subsequently removed, 
and a low concrete wall was constructed almost as far eastward as 
where the wooden groyne formerly stood. When visiting the formation 
in 1892 I noted that there was still about 14 feet of the raised beach, 
but between 8 and 4 feet of sand beneath it, the thickness between 
these limits constantly varying along the face of the cliff, thus showing 
a considerable reduction in two years. 

During a visit to Brighton in September, 1895, the changes which 
had taken place were very noticeable, owing to the rapid undermining 
of the cliff formation, and the action of the weather on the porous 
materials of which it is composed. For many years the eastern limit 
of the beds had been obscured to a more or less extent, but owing to 
the great falls that had taken place it was possible to place a limit 
upon the eastern extension of the beds. This was at a point at about 
300 yards east of the Abergavenny Inn. At this point there was 
a distinct slope upwards of the lines of bedding, these being always 
more or less obscure, but here sufficiently clear to mark the shore of 


1 Paper read before the Geological Society, an abstract of which appeared in the 
Quart. Journ. Geol. Soc., May, 1909. 


HAL Martin— Brighton Chiff Formation. 291 


chalk which bounded the small bay in which the ‘ Elephant Bed’ of 
Mantell had been laiddown. ‘The raised beach here gradually ascended 
and formed a bank resting against the chalk, and the appearance 
it exhibited was so distinct that there could be no doubt that the 
utmost limit of the formation was shown. The lines of stratification 
dipping at various angles to the west were clearly apparent until 
reaching a point 100 yards westward, where another and larger bank 
of shingle had been formed, but at a lower level. West of this the 
strata were so indistinct as to render it almost impossible to say with 
exactness how the greater number of lines of stratification proceeded. 
Being subjected to many currents they would appear in all directions 
and at all dips, supposing that the weight of the overlying strata were 
sufficient to emphasize current-bedding. At the foot of the Rubble- 
drift, where the raised beach was exposed in a horizontal position, the 
thickness of the beach varied from 4 to 5 feet, which was a greater 
thickness than was to be seen when [I visited the cliff in October, 1892. 
As the cliff had worn backward the raised beach had increased in 
thickness. Enormous blocks of red sandstone had recently been 
dislodged from the Elephant Bed, and were lying at the foot of the 
cliffs, whilst others of smaller size were seen to be embedded in the 
old sea-beach itself. 

Further falls of the Rubble-cliff, and of its chalk foundation, had 
taken place when I paid a visit in September, 1897. Ten feet of 
chalk formed the lower portion of the cliff, and above this came the 
raised beach, as much as 8 feet thick in places, consisting of rounded 
stones, with very little sandy matrix. The layer of sand at the base 
of the beach, which in 1892 was from 3 to 4 feet thick, was now 
represented by a mere trace, and since that date the sand has not 
again appeared, as the cliff has worn back. ‘The large rounded stones 
of the ancient beach rested, in fact, almost on the chalk. The Rubble- 
drift formation above was seen to be distinctly stratified, and as the 
top of the cliff was reached the flints contained in the loam became 
more jagged and less rounded. On the existing beach there were 
strewn boulders of sandstone of all sizes. One large subangular, 
ruddy-brown sandstone boulder, which had an exposed surface of at 
least 2 feet long, was seen in situ half-way up the cliff, and at the 
foot was a mass measuring 5 feet in its largest dimensions, others of 
smaller size being plentiful. Their place of origin may have been 
beyond the escarpment of the South Downs. 

In April, 1899, the raised beach by further falls of cliff had reached 
a thickness of 10 feet, resting on 10 feet of chalk. The largest 
boulders of flint were, strangely enough, on the base of the raised 
beach, there was no sand, and the change downwards was an abrupt 
one into chalk in situ. There was no layer of green-coated flints at 
the junction. Passing towards the eastern boundary of the formation, 
the beach, instead of being continuous from top to bottom, was seen 
to be here split up into a top and bottom layer, each of about a foot 
thick: the space between them was filled with ‘reconstructed’ 
chalk, containing many boulders of chalk, these increasing in size 
easterly towards the limit of the formation, until the whole came to 
present an appearance as of chalk, almost as originally laid down. 


292 E. A. Martin—Brighton Cliff Formation. 


The lower part of the Rubble-drift, which rests upon the topmost 
gravel, was seen to become more chalky in an easterly direction, and 
was made up of small semi-rounded fragments of chalk, together with 
large boulders of the same. 

Owing to the manner in which the falls had taken place, the cliff 
had been cut back more in some parts than in others, with the result 
that the lines of stratification, which were everywhere most distinct, 
dipped at a high angle towards the sea on the south. Some of these 
lines may have been due to current-bedding: in which case it would 
seem to follow that much of the upper portions of the whole formation 
is missing, having been planed away with the upper part of the chalk 
at its rear. Great masses of red sandstone, grey sandstone, and here 
and there a mass of Tertiary iron-red breccia, strewed the foot of the 
cliffs. In the raised beach I extracted two rounded boulders of 
granite, and a few rounded lamine of green sandstone. 

In May, 1899, I noted the following observations. One large mass 
of red flint breccia, full of angular flints, with the interstices filled 
with iron sandstone, lay upon the beach at the foot of the cliff, having 
apparently fallen out of the Rubble-drift. It measured 7 feet long by 
4 feet broad, and was 3 feet thick. The flints were not at all worn. 
There also lay upon the beach a mass of grey sandstone, measuring 
4 <x 1 X 1 feet, and another of red sandstone, 4 x 2 X 1 feet. Other 
masses of red sandstone, which in addition to the large one mentioned 
lay upon the beach, were all fairly rectangular in shape, but the angles 
were not at all sharp. The blocks appear to have been derived chiefly 
from the Rubble-drift, Elephant Bed, or Coombe Rock, as it has been 
variously called, whence came also a large slab of chalk rubble, full 
of rounded chalk lumps and occasional flints, which measured 2 feet 
long by 1 foot wide, but only averaging 3 inches in thickness. 

On the raised flint beach (below the Rubble-drift) round boulders 
of chalk of large size occasionally occurred: in one place, in a very 
small area, there were thirty and more to be seen. In this there 
were also occasional masses, fairly rounded, of red sandstone, generally 
occurring near the base of the old beach. Similar blocks in the 
Rubble-drift are much more angular. Beneath the disused black- 
tarred coastguard houses, there remained now but a few feet of 
Rubble-drift. 

A little east of the Abergavenny Inn, the stratification of the 
Rubble-drift is rather remarkable. A mass of reconstructed chalk 
appears to have found its way to the bed of the estuary, soon after 
the raised beach ceased to be formed, and impeded the horizontal 
deposit of the drift above it. 

Seen again in June, 1903, the formation showed considerable changes 
in consequence of falls, and in the raised beach more particularly. 
Being the most loosely accumulated portion of the whole formation, 
the falls had occurred so as to leave cave-like gaps, with a platform of 
chalk 14 feet thick below, and a roof of comparatively loose gravel 
and clayey sand. The raised beach itself was 8 ft. 3 in. in thickness, 
and this was fairly constant throughout the whole distance of 200 yards 
in which the beach was visible. 

. In those parts where the base of the beach was clearly visible, 


E. A. Martin—Brighton Chiff Formation. 293 


there was a foot of larger flint stones than those contained in the main 
mass, and large blocks of red sandstone were visible, both at the top 
and at the base of the beach. About 100 yards east of the most 
westerly visible portion of the beach it began to enclose large sub- 
angular blocks of chalk, and became of a more and more chalky 
nature in an easterly direction. 

It was not always easy to say definitely where the series of deposits 
ended in an easterly direction, and where the chalk commenced to 
again appear in situ. At somewhat over 200 yards to the east of 
where the formation is first seen, in travelling from the direction of 
Brighton, the gravel suddenly drops to about 6 inches in thickness, 
whilst upon it is chalk which has apparently been moved and 
redeposited. We appear here to be at the bank of the estuary down 
which the material was being transported, and the disturbed chalk 
has been deposited in the shallow water near the banks. In the same 
way the gravel has here been deposited very sparingly, most of it 
having been rolled into the central parts of the stream. 

So far as the Rubble-drift is concerned the section as it now 
appeared was most clearly and distinctly stratified. Especially was 
this noticeable in that portion nearest to Brighton, where it is made 
up for the most part of alternate thin bands of pale reddish clay and 
thicker bands of chalky rubble. The pieces of chalk in the rubble 
are rounded in the form of pebbles, varying in size from a pea to 
a small plum. 

About midway along the section where, in the raised beach under- 
neath, the large blocks of chalk begin to appear, there is in the 
Rubble-drift, about two-thirds the way up the cliff, a remarkable 
band, 2 feet thick, of dark reddish clay, in which are contained large 
numbers of rounded chalk pebbles, the band standing out distinctly in 
the cliff by reason of the clay being of a darker red colour than the 
surrounding clay. 

Large blocks of red sandstone were visible in the Rubble-drift. On 
the present beach I counted in a space of 50 yards square no less than 
forty fallen blocks, each containing on an average 8 cubic feet 
capacity. There were many others lying at a greater distance, but 
among them all I saw only three which were conglomeratic. All the 
others were hard red sandstone. 

Standing on the rocks at low tide I could not help being struck by 
the appearance presented at the top of the chalk cliffs where the 
degradation of the chalk was going on. The line of demarcation 
between the chalk and the subsoil was arranged in the shape of 
festoons, each festoon being 2 to 3 feet across, and extending from 
3 to 5 feet from the surface. Sometimes in the flinty clay resulting 
from the degradation a festoon had been left of white chalk untouched, 
whilst beneath it decomposition had proceeded. I had on a previous 
occasion noticed this festoon degradation in the chalk in cuttings in 
the neighbourhood of Birchington. It is still to be observed. A few 
fragments of shells (I/ya) were found at the top of the raised beach. 

A visit to the cliff in December, 1906, showed that there had been 
a tremendous fall since my last visit at a site not far to the east of the 
Abergavenny Inn. This had exposed a great rounded chalk block 


294 F. R. Cowper Reed—Fossils from Dufton Shales. 


about 2 feet long, interstratified with the raised beach, whose thickness 
varied from 15 to 20 feet. The section nearest to the concrete wall on 
the west was as follows: chalk rising out of existing beach 10 to 
17 feet, containing thick bands of flint. Above this a thickness of 
about 6 feet of raised beach, with some small sandstone boulders 
exposed therein. As the cliff recedes by denudation it will be seen 
that the raised beach varies in thickness, so that apparently it was 
laid down upon a floor that was not at one level. 

On my visit in June, 1907, great masses of the cliffs appeared to be 
slipping away in all directions, ready to fall at subsequent recurrences 
of wet or frosty weather. 

In visiting the section again in September, 1908, I found that the 
chalk base had been cut into considerably by the sea, so that three or 
four little bays had been formed. That nearest to the concreted 
embankment was about 100 yards across. Here the section was as 
follows: the lowest 12 feet of chalk had been faced by concrete, above 
which 5 feet of chalk was exposed. Next above came 12 feet of 
pebbles, the largest stones being at the base, and the topmost being 
much mixed with sand. Then came 10 feet of stratified rubble, the 
remainder -to the top of the cliff being, as a rule, but obscurely 
stratified. Beyond the baylet in which this section occurred the 
formation was well exposed for about 100 yards beyond the abandoned 
inn at the top of the cliff, and close to the site of the great fall of two 
years before. Nearly all of the material which then fell had, however, 
disappeared ; there was a little of it remaining, reaching to about 
17 feet up the cliff. There was still exhibited about 250 yards of the 
formation as a whole, reckoning east and west along the face of 
the cliff. 

It will not fail to be observed that in spite of the large amount of 
rubble which is constantly falling but little accumulates as a talus at 
the foot of the cliffs. The floor will be seen to consist almost entirely 
of chalk. It will occur to students of coast-erosion that this material 
will have to be prevented from being carried away if the cliffs are to 
be preserved. Even the lowest tide shows no trace of the material, 
and there must therefore be undercurrents which carry away the 
debris into deep water. Only the sandstone and chalk boulders 
remain for any considerable length of time. 


II].—Sepewick Museum Norss. 
New Fossits From tHE Durron SHALES. 
By F. R. Cowrzr Resp, M.A., F.G.S. 
(PLATES XXIII AND XXIV.) 
(Concluded from the May Number, p. 220.) 


Part III. 
BRYOZOA. 
CRISINELLA Wimanl, sp. nov. Pl. XXIII, Figs. 1-3. 


Zoarium composed of a group of branches of equal size diverging in 
a fari-shaped manner in nearly the same plane from a single short 


F. R. Cowper Reed—Fossils from Dufton Shales. 295 


somewhat stouter stem; the branches originate and increase by 
repeated bifurcation, which takes place at uneven intervals proximally, 
and most frequently near the stem where the branches also are less 
regularly disposed and somewhat flexuous; but further from the 
base the bifurcation is rare and more regular, and the distal portions 
of the branches are nearly straight and sub-parallel or only very 
slightly divergent. Zocecial openings present only on one side; zocecia 
arranged in 3-4 longitudinal rows, the outer row on each side 
composed of regularly disposed equidistant zocecia of equal size and 
placed alternately; peristomes prominent, laterally projecting out- 
wards as short sharply triangular spines directed forwards and 
situated about one to one-and-a-half times the diameter of the 
branches apart; zocecia in the one or two inner longitudinal rows 
without prominent peristomes, opening obliquely on the face of the 
branches, smaller than the lateral rows, and somewhat irregularly 
arranged. Reverse face of branches non-celluliferous, minutely pitted. 


mm. 


Dimensions. Length of zoarium . about 20°00 
Width of zoarlum . about 25°00 
Width of branches. . about 0°75 


Remarks.—We may compare this species with Cr. wilensis, Wiman,* 
from the Borkholm Beds, but the zocecia of the lateral rows in the 
latter do not project so much, and the reverse face is stated to be 
smooth. 


BRACHIOPODA. 
ORTHIS DUFTONENSIS, sp. nov. Pl. XXIV, Figs. 5-11. 


Shell sub-quadrate to transversely semi-elliptical, usually rather 
wider than long and widest across middle; biconvex to flattened ; 
valves shallow. Hinge-line straight, shghtly less than maximum 
width of shell; cardinal angles sub-rectangular to obtuse. Pedicle- 
valve sub-conical, weakly convex; hinge-area large, triangular, 
not steeply inclined, but making an angle of 60°-75° with general 
surface of valve, striated parallel to hinge-line, and crossed by rather 
narrow triangular delthyrium ; beak not incurved. Brachial valve very 
slightly convex, not so deep or conical as pedicle-valve, more or less 
flattened; faint median longitudinal depression occasionally present ; 
hinge-area narrow, triangular, about one-third the width of that of 
opposite valve and steeply inclined to it, but only making an angle of 
about 20° with general surface of its own valve; delthyrium narrow 
triangular ; beak inconspicuous, small, not incurved. Surface of 
valves regularly ornamented with 40-45 simple straight narrow 
rounded equidistant prominent radiating ribs, continuous from beak 
to margin, of equal strength, separated by equal rounded concave 
interspaces one-and-a-half times to twice the width of the ribs ; inter- 
spaces marked by numerous regularly and closely set concentric lines 
or lamelle becoming weaker or obsolete in passing over ribs. <A few 
shorter ribs, not more than 6-8 on a valve, are generally inter- 
calated, arising at one-third to one-half the length of the shell, and 


1 ‘Wiman, Bull. Geol. Inst. Upsala, 1900, No. 10, vol. v, pt. i, p. 181, pl. vi, 
figs. 12-16. 


296 F. R. Cowper Reed—Fossils from Dufton Shales. 


rapidly attaining the size of the primary ribs; and being set at. the 
same distance apart they are indistinguishable at the margin from the 
primaries. 

Interior of pedicle-valve with short triangular hinge-teeth and 
small sub-ovate muscle-scar, about one-fourth the length of the valve, 
rather deeply sunk and circumscribed by a ridge, weakly bilobed in 
front and composed of two small diductors separated by very narrow 
linear adductors. Pair of median vascular sinuses, contiguous and 
parallel at first, run forwards from muscle-scar, ultimately diverging 
and curving outwards laterally. 

Interior of brachial valve with narrow straight linear cardinal 
process borne on rather massive thick hinge-plate, continued anteriorly 
as broad low rounded ridge between deeply sunk but indistinctly 
defined posterior adductors; anterior adductors not visible; dental 
sockets deep, with strong-walls and stout prominent triangular crura. 

Average Dimensions.—Length 30mm.; width 25mm. The smaller 
(younger) examples are usually somewhat broader. 

Remarks.—In shape this shell much resembles some examples of 
O. calligramma, Dalm., but the species O. plicata, Sow.,' which Davidson 
regarded as merely a variety of it, is closely similar, especially in 
internal characters, but the cardinal angles are not really pointed or 
mucronate in O. duftonensis (though internal casts often give an 
erroneous impression), nor are the ribs angular, nor the interspaces of 
less width than the ribs. The typical O. calligramma is more convex, 
the beak of the pedicle-valve more incurved, and the ribs fewer, but its 
general shape and internal characters are very similar, and it agrees 
also in the simplicity of the ribs and ornamentation. The form 
ascribed to this species by Wiman,*? from the Asaphus Limestone of 
the Baltic province, appears to bear a considerable resemblance to our 
species. 

So much confusion and indefiniteness has been caused by putting 
well-marked varieties (or species) occurring on different stratigraphical 
horizons into O. calligramma, that it seems desirable to separate 
specifically this very strongly characterized local form under the name 
duftonensis. : 


ORTHIS MELMERBIENSIS, sp. nov. Pl. XXIII, Figs. 4-8. 


Shell sub-quadrate, strongly folded along median line with dependent 
lateral lobes; anterior margin angulated strongly in middle; hinge- 
line straight, equal to or slightly greater than width of shell; not 
auriculate. Pedicle-valve swollen, convex, angulated longitudinally 
down middle, sub-carinate, with lateral portions hanging down and 
flattened; beak small, elevated, prominent, rising above hinge-line, 
slightly incurved; hinge-area triangular, rather large, vertical or 
steeply inclined. Brachial valve divided into two lobes by strong 
deep median sulcus, rapidly increasing in depth and width towards 
front margin, which is angulated; beak small, with narrow hinge- 
area. Exterior of shell ornamented with about 30 fine, closely set 
é 1 Davidson, Brit. Foss. Brach., vol. iii, p. 245, pl. xxxv, figs. 25, 26; pl. xxxvii, 
ae al 
m2 Wiman, Bull. Geol. Inst. Upsala, 1907, vol. viii, p. 103, pl. vii, figs. 28-30. 


Geol. Mag.1910. ai Decade V.Vol. VII. Pl. XXIII. 


A.H: Searle del.et lith. West, Newman imp. 


New Fossils from the Dufton Shales. 


F. R. Couper Reed—Fossils from Dufton Shales. 297 


subangular ribs, nearly straight, equidistant on margin and of equal 
size, mostly dividing at one-fourth to two-thirds their length and each 
bearing a single row of rather distant short tubular erect spines, 
specially developed on the lateral portions of the valves; a fine close 
concentric lineation is also present. Interior of pedicle-valve with short 
impressed sub-triangular muscular sear widening anteriorly and broadly 
excavated in front, about one-third the length and width of the valve 
and composed of a pair of divergent diductors enclosing elongated oval 
adductors; occasionally two straight narrow divergent vascular ridges 
are traceable running forwards from the anterior outer angles of the 
muscular scar to a concentric sub-marginal ridge (often present). 
Interior of brachial valve with small rounded knob-like cardinal 
process; no thickened hinge-plate; crura short, sub-triangular; low 
narrow median ridge running forwards for about one-half the length 
of valve from cardinal process; muscle-scars indistinct. 


mm, 
Dimensions. Length ‘ > 75 
Width : : 9-0 


Remarks.—This shell somewhat resembles O. vespertilio,! Sow.; but 
the ornamentation is different and the internal characters are’ not 
quite identical, the cardinal process is not raised on a hinge-plate nor 
the adductor muscles deeply sunk, while in the pedicle-valve the 
muscle-scar is not saucer-shaped, but triangular and sub-bilobate; the 
submarginal ridge and hollow spines also are special features. It 
might be thought that this shell is merely a variety of the protean 
O. testudinarva, Dalm., using this specific name in the loose and 
comprehensive manner customary. But it seems undesirable to stretch 
this species yet more; and indeed the internal characters and surface- 
spines are quite sufficient to separate the Dufton form. 


Orruis (ScrnipIum?) EQuivocaLis, sp. nov. Pl. XXIV, Figs. 1-4. 


Shell transversely sub-fusiform, widest along hinge-line, with 
acutely angular cardinal extremities. Pedicle-valve strongly convex, 
most so in middle pertion, cardinal angles somewhat flattened; beak 
high, incurved, with triangular, steeply inclined hinge-area ; muscular 
area about one-third length of valve, sub-quadrate, not deeply impressed, 
divided into two pairs of sub-parallel scars, the outer ones being the 
diductors; teeth short, strong; small apical foramen apparently 
present. Surface of pedicle-valve furnished with pair of equal 
median ribs, smaller than the rest, and rather more closely placed, 
with 7-8 stronger subangular ribs on each side, very slightly curved 
and somewhat decreasing in strength towards lateral angles. Brachial 
valve moderately convex, but much less so than opposite valve; 
bilobed, with shallow median sinus widening anteriorly to over one- 
third the width of the valve; small, inconspicuous beak, and narrow 
hinge-area; narrow linear septum present, about one-fourth the 
length of the valve, with sub-parallel crural plates of same length on 
each side ; muscular impressions indistinet. Surface of brachial valve 
with single straight median rib rather smaller than the rest, flanked 


1 Davidson, Brit. Foss. Brach., vol. iii, p. 236, pl. xxx, figs. 11-21. 


298 F. R. Cowper Reed—Fossils from Dufton Shales. 


by 8-9 simple subangular straight ribs on each side, decreasing in 
strength towards lateral angles, and equal to or rather narrower than 
the subangular interspaces, which occasionally show a fine central 
line down them. In a few cases a small secondary rib arises close 
to the margin on the flank of a primary rib on either valve, but it 
is always short and inconspicuous. Surface of valves covered with 
coarse puncte (showing as sharp pustules on an impression of the outer 
surface) arranged with some regularity in concentric and radial rows. 


mm. 
Dimensions. Length : 5 5:5 
Width : 5 8-0 


Remarks.—This little shell is much like some species of Scenidium, 
the character of the ribbing and punctation, as well as the shape of 
the shell, recalling members of this genus. We may especially compare 
Se. elandicum, Wiman,’ from the West Baltic Leptena Limestone. 
The non-formation of a spondylium in the brachial valve is, however, 
an important difference, but Hall & Clarke* have pointed out that 
there are transitional forms between Orthis and Scenidiwm, and probably 
this species is such. It cannot be regarded as the young or a variety 
of O. actoniea, Sow., the details of the ribbing and punctation, as well 
as the internal characters, being distinctive. 

Postscript. Since the May number of the Grotoercan Maeazine 
was issued Dr. Marr has pointed out to me that there is some doubt 
as to whether the beds from which the above-described fossils were 
obtained are strictly referable to the Dufton Shales in the recent 
and restricted use of the term. Lithologically the rock resembles 
the Corona Beds and contains Lingula tenuigranulata. However, 
Professors Harkness and Nicholson employed the name Dufton Shales 
in a wide sense, including in them the Corona and other beds, and it 
is with this earlier and broader application that the term must be here 
understood. It is unfortunate when the same term has thus been 
used with two different meanings, particularly as it results from an 
alteration of its original significance. 


EXPLANATION OF PLATES XXIII AND XXIV. 
Brame XOxUET: 


1. Crisinella Wimani, sp. nov. Zoarium. x 3. 

2. Ditto. Celluliferous side of branch. <x 10. 

3. Ditto. Reverse side of branch. x 10. 

4, Orthis melmerbiensis, sp. nov. Internal cast of pedicle-valve. x 5. 
4a. Ditto. Anterior marginal view of same specimen. x 5. 

4b. Ditto. Portion of surface of same valve. x 12. 

5. Ditto. Internal cast of pedicle-valve. x 4. 

6. Ditto. Ditto. x 5. 

7. Ditto. Wax squeeze of pedicle-valve, showing ribbing. x 6. 

8. Ditto. Internal cast of brachial valve. x 4. 


PLATE XXIV. 


1. Orthis (Scenidium ?) equivocalis, sp. noy. Impression of brachial valve. «x 5. 
2. Ditto. Internal cast of same brachial valve. x 5. 
3. Ditto. Impression of pedicle-valve. x 4. 

‘ Wiman, Arkiv f. Zool. (Stockholm), 1907, Bd. iii, No. 24, p. 7, t.i, figs. 5-11 


2 Hall & Clarke, Paleont. N.Y., vol. viii, Brach. i, p. 241. 


Decade V.Vol. VIL. Pl. XXIV. 


Geol. Mag.1910. 


és 
Jo. «22 West, Newman imp. 


New Fossils from the Dufton Shales. 


A.H.Searle del.et lith. 


L. J. Wills—Wind-worn Pebbles in Gravels. 299 


Fic, : 
3a. Orthis (Scenidium?) equivocalis, sp.nov. Portion of surface of same valve. x 10. 
4. Ditto. Internal cast of same pedicle-valve. x 4. 
5. Orthis duftonensis, sp. nov. Internal cast of brachial valve. Nat. size. 
6. Ditto. Internal cast of pedicle-valve. Nat. size. 
7. Ditto. Internal cast of brachial valve. Nat. size. 
8. Ditto. Internal cast of pedicle-valve. Nat. size. 
9, Ditto. Brachial valve of complete specimen. ~ 1}. 
9a. Ditto. Posterior view of same specimen. x 1. 
94. Ditto. Lateral view of ditto. x 14. 
9¢. Ditto. Portion of surface of ditto. x 23. 
10. Ditto. Brachial valve of another complete specimen. Nat. size. 
11. Ditto. Pedicle-valve of another complete specimen. x 13. 


ITV.—On tHE occuRRENCE oF WIND-worRN PEBBLES IN HIGH-LEVEL 
GRAVELS IN WORCESTERSHIRE. 


By Lronarp J. Wits, M.A., F.G.S., Fellow of King’s College, Cambridge. 
(PLATE XXY.) 


IND-WORN pebbles are somewhat rare in England, and 

accordingly it may be of interest to record the occurrence 

of a deposit of which they form a prominent feature. ‘This has been 

met with in several quarry-sections at Hill Top, near Bromsgrove in 

Worcestershire, at about 350 feet above sea-level. I am indebted to 

Mr. Willcox, the owner of one of the quarries, for pointing out these 
pebbles to me. 

The quarries are opened in the Lower Keuper Sandstone, and the 
deposit under consideration occurs on the ridge of the hill in channel- 
like depressions cut out of the underlying sandstone. To the north- 
west there are patches of gravel capping the hill, but so far I have not 
detected wind-polished pebbles in them, and I am rather inclined to 
regard the two deposits as distinct.! 

As exposed in the quarries, the deposit is a loose red-brown sand, 
with occasional streaks of tough clay, and may attain a thickness of 
about 10 feet. In places the sands are blackened by an infiltration 
of an oxide of manganese. In cases where pebbles le in clay, 
sand-grains may be cemented to them by this oxide. The sand is 
largely composed of fairly fine quartz-grains, usually angular, and 
rarely rounded, but there is also a great quantity of very much smaller 
and quite angular material, and a few large flakes of white mica. 

The wind-worn pebbles le in a somewhat discontinuous layer 
towards the base of the deposit and occasionally higher up in it. 
They are, as I hope to show, more or less highly polished, according 
to the nature of the material of which they are composed, but nearly 
all show a dimpling which has resulted from the selective action of 
the wind. These little depressions are polished like the rest of the 
stone. But possibly the most striking feature that nearly all of the 
pebbles show is the presence of sharp angular ridges, which give 


1 One large quartzite pebble, having a very typically wind-cut appearance, has 
been found about 14 miles to the north-east of Bromsgrove, while other pebbles 
with a considerable polish may be seen in the fields near Apesdale. So it is possible 
that similar deposits to those at Bromsgrove may eventually be discovered im that 
neighbourhood also. 


300 L. J. Wills—Wind-worn Pebbles in Gravels. 


them a more or less facetted appearance. I have not been able to 
convince myself that any large face has actually been produced by 
the wind, but natural fractures and pre-existing faces have been 
ground down, and the sharp intervening ridges have been preserved 
and accentuated. This could not possibly have come about under 
water. 

It may be of interest to examine the manner in which the same 
erosive action has affected different kinds of rocks. The pebbles 
found are capable of derivation either from the Bunter Pebble Beds 
or from glacial deposits. 


1. PEBBLES PROBABLY DERIVED FROM THE Bunter. 


(1) A mottled green and purple grit (Pl. XXV, Fig. 1).—On the side 
shown in the figure a typical dimpled surface with a greasy lustre is 
seen, while the other side preserves the water-worn contours that it 
possessed in Bunter times. The sharp edge seen round the outside 
is to be noticed, since it gives evidence of actual cutting power in the 
sand-blast. 

(2) A small pebble of black felstone with veins of quarts (Pl. XXV, 
Fig. 2).—This is polished all over. ‘The sharp line up the centre, 
shown in the photograph, possibly indicates an edge modified by 
wind-action, as a result of the grinding down and remodelling of 
a natural fracture. In this way a rude dreikanter form is obtained. 
It is possible, though I do not think it probable, that the shaping is 
entirely due to wind-action. The selective action of the sand-blast 
is seen in the way the quartz veins stand out. 

(3) Coarser grits —YThese are chiefly noticeable in regard to the 
projection of the quartz-grains and to polishing of the depressions 
between. 


2. PEBBLES PROBABLY DERIVED FROM GuLAcrIAL Deposits. 


(1) North Welsh Andesitic Ashes.—Boulders of this kind are 
common and may attain a large size (up to 13 or 14 inches through). 
They vary slightly in composition, but they nevertheless show much 
the same external phenomena. They are not so highly polished as 
are the quartzite and quartz pebbles derived from the Bunter, but are 
characterized by an irregular pitting and grooving. The latter is 
really more comparable te the elongation of the pits in a common 
direction than to actual grooving. In a very coarse ash with large 
quartz-grains these stand out and are well polished. 

(2) FKelspathic Grits (probably Carboniferous).—Two specimens of 
very similar grits have been found. One is about 9 inches long and 
shows the effect of the wind-erosion on the rock as a whole, whereas 
the other is quite small and, though equally angular, is instructive as 
illustrating the selective action of the wind on heterogeneous material. 
The sides of the larger stone have the softer parts worn away in more 
or less parallel strips. Its lower surface is irregularly flaked and 
barely polished at all. 

(3) Sclvecfied Crinoidal Limestone (P1. XXV, Fig. 3).—These pebbles 
take a very high polish and look as if they had been rubbed with oil. 
There are occasionally deep round pits in them which are not so well 


a 


L. J. Wills— Wind-worn Pebbles in Graveils. 301 


polished. ‘These represent the hollow casts of crinoid stems. It may 
be noted that these silicified limestones are always more or less angular, 
but this does not preclude the possibility that they have been derived 
from the Bunter. 

(4) Gannister (Pl. XXV, Fig. 5).—A very fine specimen of a 
gannister pebble is here figured. It was found by Mr. Willcox, who 
sent it to me. On the reverse side it is smooth but not intensely 
polished, whereas on the side figured a very high glaze is seen. More 
remarkable still is the sharp angular ridge which surrounds the top 
of the stone. The upper surface has an appearance as if the rock 
possessed a slight conchoidal fracture along which pieces had flaked 
off under the influence of frost. ‘The hollows left have been highly 
polished, and the ridges between are quite sharply defined and 
angular. At (a) we can see how the erosive agent has picked out 
a natural joint in the rock and enlarged it. 

This fine specimen gives strong evidence in favour of the conclusion 
that these cases of polishing are due to the action of wind-erosion, 
for it is evident that the wind is the only agent capable of polishing 
concave surfaces and, at the same time, of leaving the ridges between 
the depressions sharp. 

In most of the cases considered above where a dreikanter form has 
been observed, it is due to accidental fracture. But there are instances 
where one is tempted to say that the general shape is the direct result 
of cutting by a sand-blast, the pebble having a roughly tabular form 
with a flattish upper surface surrounded by a sharp ridge. Such 
shapes are common among desert pebbles from Wadi-Halfa in Egypt, 
and may there represent the first stage in the production of a 
dreikanter. A specimen of this type preserved in the Sedgwick 
Museum, Cambridge, is here illustrated on Pl. XXV, Fig. 4, and may 
be compared with Pl. XXV, Fig. 5. 

I¢ is striking that the sand in which the stones lie is composed of 
angular material. But itis at the same time to be remembered that 
wind-rounded sand-grains are almost always of larger size than those 
found here. 

The presence of Welsh erratics among these polished pebbles fixes 
the age of the deposit as either Glacial or post-Glacial. This is of 
interest since, throughout North Germany, wind-cut pebbles are found 
lying on the Boulder-clay at the base of the Loess. In England too 
one wind-cut pebble has already been recorded which was probably 
derived from glacial deposits.! 

The remaining records of wind-polished stones in England (other 
than recent) show that probably their production was a rather local 
phenomenon and not likely to be very widely observed. Further, they 
are not confined to beds of one age. Mr. Clement Reid, to whom my 
thanks are due for help in dealing with this question, mentions some 
from Dewlish, where they appear to be late Pliocene or of the age of 
the Cromer Forest Series.” 

Prestwich? found similar pebbles at Portland. They were there- 

1 F. A. Bather, Proc. Geol. Assoc., 1900, vol. xvi, p. 396. 


2 C. Reid, ‘‘ Pliocene Deposits of Britain”: Mem. Geol. Surv., 1890, p. 206. 
3 J. Prestwich, Quart. Journ. Geol. Soc., 1875, vol. xxxi, p. 29. 


302 Bernard Smith—Upper Keuper, East Nottinghamshire. 


associated with Llephas antiquus, EL. primigenius, and ELquus fossilis, 
etc. Their age is probably post-Glacial. 

A second record by Mr. Clement Reid is of especial interest to us. 
He found Paleolithic gravels with polished pebbles at Savernake 
Forest, and his comments on the climate of those times are pertinent. 
He argues that it must have been milder than on the Continent, where 
steppe conditions were prevailing, and yet that ‘‘ we have indications 
of drought in some of the mollusca and small mammals—perhaps also 
in the extreme poverty of the flora’’.t Yet the paleontological 
evidence in favour of steppe conditions is still meagre. Lagomys 
pusillus and Spermophilus are known from the Ightham Fissures, 
while the Saiga antelope is recorded from the Thames Valley. These, 
in that they are quite typical steppe animals, should form good 
evidence of the prevalent climate. 

I think, therefore, that we are justified in putting this occurrence 
of wind-worn pebbles on record, as another possible link in the chain 
of evidence in favour of dry conditions verging on those of the present- 
day steppes having occurred locally in Great Britain in post-Glacial 
times. ‘The abundance of fluviatile deposits belonging to this period 
precludes the possibility of true steppes having existed over wide areas 
in our country. But at the same time, though the melting and 
retreating ice-sheet provided great quantities of water, yet the climate 
may have been fairly dry, especially if, as Mr. Harmer has suggested, 
the prevalent winds blew at that time from the east. It must, 
however, be confessed that the general prevalence of steppe conditions 
in this country is still very far from proven. 


EXPLANATION OF. PLATE XXY. 


Wind-worn pebbles of fine-grained felspathic grit. 4. 
‘s i pebbles of black felstone. 4. 


Fig. 1. 
2. 

phe Bc 94 pebbles of silicified limestone. 2. 
4 pebble from Wadi-Halfa, Egypt. 3. 


eaiuh Os es pebble of Gannister. 4. 


Figs. 1-4 photographed by author ; Fig. 5 5 by W. Tams. 


oie) bed 


V.—Tne Urrre Kevrrer Sanpstones oF Kast NovrincHAMSHIRB.” 
By Breryarp Smirx, M.A., F.G.S. 
(PLATE XXYVI.) 


HE Keuper rocks of East Nottinghamshire occupy almost the 
whole of that part of the county, striking slightly E. of N. and 

W. of S., and dipping at a very low angle in an easterly direction. 
They have been described by many competent local observers such 
as the Rev. A. Irving, Messrs. J. Shipman, E. Wilson, J. F. Blake, 
W. J. Harrison, and A. T. Metcalfe; and also by W. H. Dalton and 
W. T. Aveline in several publications of the Geological Survey 
between 1879 and 1888. During the recent survey the succession 


1 C. Reid, Swmm. Prog. Geol. Surv. Gt. Brit. for 1902, p. 207. See also the 
same author in Wat. Sci., 1893, vol. ii, p. 367. 
2 With the permission ‘of the Director of the Geological Survey. 


Gnron. Mac. 1910. 


Pratt XXV. 


Wind-worn pebbl 


SS 


au peat | 


<a 
ven wee 
i 
s 
’ re 
a i 
rs 
SS en oe ah 
ae 


ou 
oe 
—— 


it 


s 1s eu 


Bernard Smith—Upper Keuper, Hast Nottinghamshire. 303 


has been mapped and described once more,’ but in no case has 
particular attention been paid to the composition and structure of 
the sandstones of the Keuper Marls, which are usually dismissed 
by writers in as few sentences as possible. The following notes 
collected between 1906 and 1910 may therefore serve a useful purpose 
in supplementing previous descriptions of the Marls, and may throw 
light upon the probable method of accumulation of this somewhat 
monotonous formation. 

Surface Features.—The sandstones of the Keuper Marl of Notting- 
hamshire are locally known as ‘skerries’, and the relief and 
characteristic appearance of the outcrop is directly due to these 
‘skerries’ with their associated beds—a combination which I shall 
refer to as ‘skerry-belts’. In the almost complete absence of drift 
the marls have weathered in such a way that practically every feature 
is the expression of some resistant bed which may be quite invisible 
at the surface. In rare cases this may be a hard blocky marl, but 
usually it is a skerry-belt. 

If the Keuper Marl plateau, where least dissected, is followed in 
the direction of the dip, the successive skerry-belts encountered— 
unless individual skerries are very thick and hard—do not make 
much show, but come on gradually, first the lower layers and then 
the higher ones. When, however, the plateau is well dissected, 
the beds forming the belt stand out boldly, especially where the 
strike-streams trench the upland close to the now well-developed 
escarpments. 

In the north-eastern part of the county the lower skerries form 
an upland gently sloping in an easterly or south-easterly direction 
drained by dip-streams flowing to the Trent. Standing upon one 
of the divides between the valleys and looking north or south, ridge 
after ridge, supporting village after village, may be seen at the same 
level. From this level the slopes drop in steps over successive skerry- 
belts to the valley bottoms, the edge of each remnant of the upland 
being the edge of the valley upon that side; hence the characteristic 
scenic effect is the straight sky-line, whether in long ridges or isolated 
hills. 

Skerry-belts—The skerry-belts—usually about 6 feet thick—are 
composed of alternations of micaceous sandstone, shale, and marl with 
occasional veins of fibrous gypsum, and are unexpectedly persistent, 
although individual beds of stone may occasionally thin out whilst 
others become thicker. 

The sandstones vary from an exceptional thickness of 3 feet to less 
than half an inch, the thicker beds being often split up by sandy 
shales. In the belts it is common to find (in upward succession) red 
marls and clays followed by a thin layer (1-2 inches) of green and 
blue clay, which is sueceeded abruptly but conformably by a sandstone. 
Above the latter there is a gradual passage through green to green- 
red and finally red clays and shales. Pseudomorphs after salt crystals, 
formed at the surface of the green-blue clay, are frequently found on 
the bottom surface of the sandstone. The sandstones are pale in 


1 “The Geology of the County between Newark and Nottingham’’: Mem. Geol. 
Sury., 1908, pp. 35-54, and in Swmmaries of Progress for 1907-8. 


3804 Bernard Smith—Upper Keuper, East Nottinghamshire. 


colour (white, cream, grey-green, or pale-blue), but if thin may be 
stained pink externally. The shales often have the ‘ watered’ 
appearance characteristic of the Waterstones,’ and were evidently 
formed under the same conditions. Chocolate or bright-red marl 
frequently passes abruptly into bright-green marl in both a vertical 
and horizontal direction. Small galls of red marl up to half an inch 
in length frequently occur in the green shales and green ones in 
the red shales, and it is noticeable that the green shales are often of 
a coarser texture than the red. 

The Skerries.—Mr. W. H. Dalton? describes the majority of the 
sandstones in the Keuper Marl as “very fine-grained, compact, grey 
or even pure white, and very hard; in the latter case containing 
a high percentage of carbonate of lime . . . It is too soft for traffic, 
but hardens considerably by exposure, which permits of the deposition 
of crystalline carbonate of lime previously in solution in the pores of 
the stone. The cementing material appears to be wholly carbonate of 
lime, the rock falling into sand by submersion in hydrochloric acid ”’. 
He further adds that there are ‘‘thin bands of sandstone, sometimes 
rather coarse, soft, and of the same deep colour as the marls”’. 
These last-mentioned sandstones are thin and so scarce that they 
are almost unnoticeable, and pink in colour rather than deep red, like 
the marls. On hammering they generally expose a pale core, which 
suggests that the reddish tint is due to weathering. 

The skerries fall into three types in ascending order— 


1. Pale sandstones with carbonates. 
2. Pale flaggy sandstones with more silica. 
3. Coarse sandstones with larger rounded grains, mostly siliceous. 


1. These form the main stone horizon near the base of the division, 
and give rise to the most characteristic plateau features. They 
frequently exhibit drift-bedding and ripple-marking, or show a peculiar 
contorted arrangement of the lamine (suggestive at first sight of 
concretionary action). Here and there lumps of softer laminated 
stone lie rolled up and embedded in non-laminated portions and tend 
to weather out, giving the stone a honeycombed appearance. 

Two slices were examined microscopically, and in both cases the 
rock contained quartz and carbonates in about equal proportions. 
The first was a compact typical building stone (Maplebeck, Notts), 
slightly banded. It consists of small angular quartz-grains of very 
similar size and derived rhombs of dolomite. The dolomite never 
occurs as plates enclosing the quartz-grains, but as rhombs of various 
sizes, with rounded angles and broken faces. A little calcite may be 
present, but is not very much in evidence. The quartz-grains— 
generally less than 335mm. in diameter—are derived from plutonic 
rocks and are full of fluid cavities. The banded appearance is due to 
the scarcity of quartz, which drops from 50 to 10 per cent. along 
certain lines, and must therefore be due to sedimentation. 

The second example was a softer-looking ripple-marked rock, 


1 The term originally used by Mr. G. W. Ormerod, because the surfaces of some of 
the ‘beds had a watery appearance, like watered silk. 


2 


2 « The Geology of the Country around Lincoln ’’?: Mem. Geol. Sury., 1888, p. 8. 


Bernard Smith—Upper Keuper, East Nottinghamshire. 305 


similar to the last, but in which the quartz-grains are of more uneven 
size. The lamine of the ripple-marks are in this case due to 
either dolomite or quartz rising to 90 per cent., as compared with 
10 per cent. of the other constituent. Part of the rock is patchy, 
i.e. contains nests of quartz or dolomite in the above proportions. 
The quartz shows strain shadows, and the larger grains (;+mm.) 
contain fluid cavities with gas bubbles. The dolomite granules, 
much smaller than the quartz-grains, are often stained with limonite. 
There are a few accessory minerals of no great importance, such as 
papretite, zircon, sphene, and a pale pleochroic greenish-brown mica. 

The second series commences at from 360 to 370 feet above the 
hee of the Keuper Marls, and consists of thinner and less persistent 
sandstones than those of the lower series. They have a siliceous, 
often banded, appearance, and weather out as rough, slaggy- looking 
pieces of stone, with a brown or blue-black stain due to iron or 
manganese compounds, strikingly different from the paler and cleaner 
fragments of the lower skerries. 

A slice of a wavy-banded specimen shows that the light bands 
(reflected light) consist of quartz with small brightly polarizing 
dolomite granules or rhombs, which make up perhaps 380 per cent. 
of the rock. The remaining 70 per cent. is mostly quartz with 
a little accessory twinned felspar (aoorodiae and anorthoclase). The 
angular quartz-grains (all about ;+; mm. in size) show strain shadows, 
and occasionally pack as a mosaic with little or no dolomite between 
them. Some appear to be cemented together or to be parts of 
a previous quartzite. A little detrital calcite mud may be present, 
and angular cavities in the slice may represent plates of that mineral. 

3. In hand-specimens the third type consists of flaggy and false- 
bedded sandstones, in colour white to bright-red, resembling millet- 
seed sandstones with rather loosely cemented grains. These rocks 
are found some 120 feet below the base of the Rhetic beds, or 
about 580 feet above the base of the Keuper Marls. 

Under the microscope the grains are seen to be of two sizes. The 
larger are often beautifully rounded, and average 4mm. in size; 
the smaller are of similar composition, but more angular, occupying 
the interstices between the first. The majority consist of quartz 
(percentage over 95), with strain shadows and fluid cavities with 
bubbles, and there has sometimes been a secondary growth of silica 
upon the surfaces of the grains. Felspar with fine lamellar twinning 
(? oligoclase), fine quartzites, and quartz-schists are also present. An 
interesting point is the appearance of several grains composed of 
dolomite and quartz, having the appearance of rolled fragments of 
a rock resembling that last described. 

Ripple-marks and Contorted Structures. — These structures are 
commonly found in the lower sandstones, but are not confined to 
them. ‘here seems to be no doubt that the drift-bedding and ripple- 
drift was the result of water-action, one set of ripples “being some- 
times partially destroyed and another laid down in a slightly different 
position (Fig. 1). Occasionally the same slab shows ripples crossing 
a second set at right angles. 

In the first two skerry types the quartz fragments and dolomite 

DECADE VY.—YOL. VII.—NO. VII. 20 


306 Bernard Smith—Upper Keuper, East Nottinghamshire. 


fragments are very even grained, their different percentages in the 
lamine being doubtless due to oscillations in the amount of supply 
during sedimentation. The smaller size of the dolomite grains, as 
compared with the quartz, may be explained by the higher specific 
gravity of the dolomite. 

The contorted structure shown in Pl. X XVI, Fig. 1 is not so easily 
explained. If the upper part of such aslab is stripped off—as it often is 
by weathering—an irregular lumpy surface, consisting of smooth curves 
and folds, would be exposed. This appearance, taken in conjunction 
with the occurrence of dolomite, is suggestive of concretionary action ; 
I would, however, attribute it mainly to disturbance of the ripples 
while the deposit was still in a soft and pasty condition. In a few 
cases, however, there is a suggestion that in addition to ripple-marks 
the layers of sediment were arranged in rounded curves (somewhat 
like those in some parts of the Cotham Marble), but afterwards disturbed 
by current-action. Freshets of water, producing swirling currents, 


Fic. 1. Stone in wall of Sutton Church, Notts, with contorted lamine. Nat size. 


would sweep along with them a heavy burden of sand, and tear up 
(Fig. 1) or contort underlying ripple-marked layers, embedding them 
in a structureless deposit. When the flood-waters began to come 
to rest a layer of ripple-marked sediment passing upwards into 
drift-bedding (Fig. 2) would be deposited upon the top of the broken ' 
and contorted layer. 

An actual case of the formation of such structures is quoted by 
Mr. A. W. Rogers, of the Cape Geological Survey, with whose per- 
mission the accompanying photograph (Pl. XX VI, Fig. 2) is reproduced. 
“At the mouth of the Prieska ravine a certain bed of alluvium on the 
left bank has its lamine contorted. They often stand vertically, and 
are even curved into the shape of an inverted bulb. Above and below 
this layer the lamine are false-bedded or lie flat.”* He attributes 

! Sorby (Quart. Journ. Geol. Soc., 1908, vol. Ixiv, p. 197, pl. xiv) has shown how 
the sandy ashes of the Langdale slates were deposited sometimes as ripple-drift, 
which became torn up and contorted as the velocity of the sediment-bearig current 
increased. Sorby’s experiments seem to show that a current of about 2 inches per 
second in shallow water would suflice to form ripples in sediment as fine as that of 
these skerries. A velocity of 6 inches per second would wash up and destroy them. 

? Cape of Good Hope, Thirteenth Annual Report of Geol. Commission for 1908, 
p. 107. 


Bernard Smith— Upper Keuper, East Nottinghamshire. 3807 


the contortions to swirling waters which he saw above the spot and 
whose action is clearly traced in the Koegas ravine, where for some 
800 yards above the mouth laminated strongly false-bedded alluvium 
is common, on the left bank dipping up the ravine, on the right bank 
down the ravine. 


err = 
Leazzzzzz Zz 
YZ LALLA LL 
CLE ZL LAAZEZLLLLLo EF 


Fie. 2. Stone in south wall of the tower, Fledborough Church, Notts, showing 
drift-bedding ripples. 


In the above example the contorted and brecciated appearance 
(Fig. 2) seen so frequently in the skerries is reproduced to perfection. 
It is also to be noted that the laminze of the dolomitic sandstones are 
overfolded and tucked away in synclinal form, but no one lamina ever 
forms a completely closed sphere or ellipsoid as we should expect if 
the structure was concretionary. In the channel of a stream issuing 
from a borehole I recently noticed ripple-marks being formed. The 
sediment was a silt composed of the debris of Coal-measure shales and 
sandstone and coaly fragments, which formed a deposit not at all 
pasty; yet pressure of the hand behind some of the ripples caused 
even this very liquid type of sediment to become contorted or slightly 
overfolded. 


Fie. 3. Stone in wall of Sutton Church, Notts, with broken lamine. Nat. size. 


The idea that the contortions may be due to contraction during 
dolomitization is dispelled when we remember that the disturbed 
layer is in many cases both underlain and overlain by a normally 
ripple-marked layer of identical minerals and percentage composition. 

Actual disturbance by water-action is also shown by the occurrence 
of the above-mentioned pieces of laminated and ripple-marked sand- 
stone in the more compact beds. ‘they have been torn away bodily 
and carried forward by the rush of muddy water and embedded in 
curved and twisted patches, which now weather out more easily 
than the non-laminated matrix. 


308 Bernard Smith—Upper Keuper, East Nottinghamshire. 


Depth and Extent of Waters.— Waterstones and Keuper Marls 
alike were deposited in what was presumably a shallow salt sea or lake 
of great extent, situated to the east of a southerly projecting spur 
(the Pennines) of an upland which was under continental climatic 
conditions; so that in the hot season a great amount of weathering 
took place in the dry way. In the wet season the debris was swept 
down into the inland sea, which temporarily increased in extent and 
depth owing to the influx of fresh water. 

All the time that the basin was filling up with sediment the bottom 
must have been slowly sinking—perhaps most rapidly towards the 
end of the period—so that the water-level and depth was more or 
less constant. 

The abundance of the skerries in the lower part of the marls and the 
large deposits of massive gypsum in the higher parts suggests that the 
waters were deepening and at the same time becoming more saline. 
But, on the other hand, the skerries never entirely ceased to be formed, 
and even the higher ones (which contain quartz-grains of two sizes and 
therefore may indicate deeper water'), a long way from the western 
shore, are ripple-marked and bear salt pseudomorphs; hence the 
increase in depth must have been trifling. In fact, isostatic conditions 
seem to have prevailed throughout the area. 

The abundance of rather coarse red sandstone, a basal conglomerate, 
and sandy shales, together with the frequency of salt pseudomorphs, 
ripple-marks, and sun-cracks,” suggests that the Waterstones near their 
outcrop were accumulated in very shallow water, or even that large 
tracts with isolated pools were laid bare from time to time. Again, 
the plant and fish remains found in the Waterstones, and in the 
Keuper Marls elsewhere, are usually fragmentary, and occur in 
sediment obviously deposited near a shore-line where the rivers 
would bring down drift vegetation and render the salt-waters com- 
paratively fresh and suitable for animal life. The fish found by the 
late E. Wilson at Colwick Wood were supposed by him to have been 
trapped in the shallows of a lagoon and destroyed either by the 
waters drying up*® or becoming increasingly saline. When traced 
eastward beneath the surface, however, the Waterstones become more 
like the Marls above them. In a boring at Rampton they were 
with difficulty separated off from the Marls, and at Lincoln‘ their 
distinguishing characters are almost wholly absent, only a very 
little sandstone indeed being present. 

Thus in the east we seem to have a more open water area which in 
the first case was probably quickly flooded, so that the typical shore- 
line phenomena of the Waterstones were not there developed and the 
conditions of sedimentation were similar for both Marls and Waterstones. 

The thickness of the Keuper between Tuxford and Lincoln is 


1 The coarser sediment of the higher skerries was probably wind-borne to the face 
of the waters. 
: ‘ I have only seen one slab with casts of sun-cracks from the Keuper Marls of this 
district. 

3 Dr. H. H. Swinnerton has recently discovered footprints and fish-remains in the 
Waterstones of Sherwood, Nottingham (Grou. Mac., May, 1910, p. 229). 

+ According to Mr. Henry Preston, Grantham. 


Bernard Smith— Upper Keuper, East Nottinghamshire. 309 


remarkably constant (nearly 900 feet), and contrasts strongly with 
the variable thicknesses encountered near the old shore-line near 
Nottingham, a fact which once more emphasizes the uniformity of 
subsidence and isostatic conditions in the centre of the depression. 

The presence of massive gypsum near the top! of the division at 
Newark seems to favour the idea that the water also became 
increasingly saline. The fibrous and platy gypsum in the lower 
skerry-belts was no doubt deposited as the marls dried and got rid of 
their included waters. 

Source of Sediment.—As to the source of the dolomite, its detrital 
nature and manner of deposition show that it was not formed where it 
is now found, but was probably deposited contemporaneously near the 
shore-line and then swept out by current-action. 

Dr. C. G. Cullis recently reported on the occurrence of small isolated 
rhombs of dolomite* in the Keuper Marls of Westbury-on-Severn and 
as far north as Worcester. The crystals are extraordinarily perfect 
and always very minute, and occur in both the red and green marl, 
sometimes in great profusion. A washed residue of the marl contained 
practically nothing but quartz-grains and these dolomite rhombs; 
that is to say, the constituent minerals of the skerries are also 
scattered throughout the shales and marls associated with them. 
Dr. Cullis is inclined to think that the dolomite rhombs were 
precipitated directly from solution. They may have been in the first 
case; in one band at least (from the Waterstones), which was 
examined microscopically, the dolomite seems to have been formed in 
situ. In most cases, however, the rhombs have suffered attrition by 
being drifted some distance together with the quartz and other detrital 
fragments. 

The occurrence of grains of dolomitic sandstone in the higher type 
of skerry is suggestive, as showing that some dolomitic rocks were 
also exposed to denudation at this time. Most of the quartz and 
felspar no doubt was derived from Carboniferous sandstones and grits, 
and to Carboniferous rocks also we must attribute the basis of the 
finer caleareous and dolomitic shales and marls. 

The Finer Deposits.—Just as there are differences in the lithological 
characters of the skerries, so also the marls themselves differ from 
point to point and occur in lithological belts of perhaps as great 
horizontal extent as the skerries. The differences are brought out by 
the character of the soils on the outcrop. It is well known that the 
marls contain a high percentage of silica and are practically fine silts : 
the coarser silts pass into sandy and dolomitic shales or marls, which 
break down into a sandy soil; the finer ones behave as tough homo- 
genecus clays. Above a skerry it is common to find sandy shales pass 
gradually upwards into sandy marl, showing ripple-marks, and then 
into fine homogeneous marl. 

Sorby has shown that such homogeneous clays may be deposited 
either by gentle and uniform currents drifting along fine sediment to 
spots where there is scarcely any current at all, or to quick deposit of 

‘ Massive gypsum is recorded from a lower horizon at Clarborough, north of 
Retford. 

* Rep. Brit. Assoc. for 1907, pp. 506, 507. 


3810 Bernard Smith—Upper Keuper, East Nottinghamshire. 


cohered mud from tranquil waters. The passage from sandy shales 
to fine marls mentioned above rather favours the first of these 
alternatives. In addition we must not forget that wind-borne dust 
and sand would also add largely to the fine sediment. The rate of 
deposit in muddy rocks may be as much as 9-18 inches per hour 
according to Sorby, the shaly character of the coarser parts being due 
to a gentle current of varying velocity carrying sediment of various 
degrees of fineness. 

We may, then, sum up the formation of skerry-belts as follows :— 

(a) Rather shallow waters slowly becoming desiccated during a dry 
period; deposition of fine sediment as marl, some possibly wind- 
borne and distributed by water, for under favourable conditions 
even the blocky marls show signs of bedding and current-action. 
Formation of salt crystals in the upper clayey layers. 

(6) Influx of fresh water bringing sediment. Casts taken of salt 
crystals, now dissolved out. Formation of skerry by successive 
freshets of water and current-action. 

(c) As supply of coarse sediment failed, laminated shales were 
deposited, finally passing into fine sediment as marl. Conditions 
repeated for every skerry. 

On this idea, other things being equal, every individual sherry 
represents a wet spell of greater or less duration or degree. A skerry- 
belt might therefore represent a sequence of wet seasons, and we 
have an explanation of the persistence of the skerry-belts and general 
types of sediment over large areas whilst the individual skerries are 
of less extent. 

Colour Changes.—A discussion of the variegated colours of the 
Keuper is beyond the limits of this paper; one or two remarks, 
however, may not be out of place. We cannot assume that all the 
red beds were once green, or that all the green beds were once red. 
There have been changes about tree-roots and along joints where 
red marl has become green, but the deciding factor for the big colour 
changes must have been one connected with the mineral solutions 
in the water and their concentration. In this connexion the above- 
mentioned gradual change in colour with each skerry when well 
developed is suggestive. With the influx of fresh waters the 
conditions which previously brought about a red colour were upset, 
and a green took its place, followed by alternating red and green 
conditions until the red finally prevailed as the waters became more 
concentrated. 

Goodchild? has pointed out that the presence of organic and 
humic acids prevents the deposition of iron as ferric oxide—and 
most of the fossiliferous beds in the Keuper are grey or green. It 
does not therefore seem too great an assumption to suggest that 
the first torrential? waters sweeping down from the land not only 
cooled and diluted the previous solutions, but also carried with them 
organic remains and humic and organic acids which would for a time 


1 <¢ Desert Conditions in Britain’’: Trans. Geol. Soc. Glasgow, 1898, vol. xi, pt. 1, - 
pp. 87, 89, 90. 

2 Especially if humid conditions prevailed in the upper parts of the inland basin 
as in the case of the Dead Sea and the Great Salt Lake. 


Gron. Mac. 1910. Pirate XXVI. 


ip eA et 


TRS 


A. W. Rogers. 


D. M. S. Watson—Chelonian from the Purbeck, Swanage. 311 


prevent the formation of red beds and perhaps also bleach the red 
marl immediately beneath the skerries. 

My thanks for criticism and suggestion are due to Mr. G. W. 
Lamplugh, and to Mr. EK, EK. L. Dixon whose knowledge of dolomitie 
rocks is both varied and extensive. 


EXPLANATION OF PLATE XXYVI. 
Fic. 1. Stone, 14 by 7 inches, in the east wall of south porch, Sutton-on- Trent 
Church, Notts. 
ee aroken and contorted alluvial silt in the left bank of the Prieska ravine 
where it opens on the Orange River. 


VI.— Giyerops rverimuerers (Lyp.), A CHELONIAN FROM THE Purbeck 
_ OF SwaNaGE. 

By D. M.S. Warson, B.Sc., the Victoria University of Manchester. 
‘{\HE Manchester Museum contains two ‘turtles’ from the Middle 

Purbeck Cap and Feather Bed of Swanage which are referable 
to Lydekker’s? Thalassemys ruetimeyert. The first of these, L. 7017, 
was purchased from Swanage in 1906, and consists of a carapace 
lacking all the marginals, but otherwise complete and undisturbed. 
The second, L. 9520, was obtained by the writer from a quarry some 
2 miles west of Swanage in March of this year. This specimen, 
although crushed, 1s important because it retains the whole shell, both 
carapace and plastron, with the exception of some of the peripherals. 


DEscRIPTION OF SPECIMENS. 


Carapace (Fig. 1).—The carapace is much depressed and is markedly 
cordiform. Its length from the anterior end of the nuchal to the 
posterior border of the last suprapygal is 28 cm., and the maximum 
width across the third costals is 26 em. The nuchal isa large hexagonal 
bone, the anterior edge of which is concave; its dimensions are— 
length 3 cm., breadth 6:8 cm. 

In. the two Manchester specimens two distinct bones lie between 
the inward ends of the first pair of costals; in Lydekker’s type- 
specimen, as is shown in his figure, and as Dr. Andrews has kindly 
checked for me, there is only one bone occupying the same space. 

The first of these bones is probably homologous with that which 
has been figured by Hay” and others in Chisternon, Boremys, 
Aspideretes, and Plastomenus as the preeneural; its condition in the 
present case is very similar to that which obtains in the last three 
genera. The neurals are generally hexagonal, with the face for the 
corresponding costal much larger than that for the preceding one. 
All eight are at present well developed. 

Two suprapygals are shown in L. 7017: the first isa hexagonal bone 
having a short border for the eighth neural and a long curved edge for 
the second suprapygal. The second suprapygal is quadrilateral and 
much wider in front. The costals gradually decrease in length from 
front to back; no pair meets in the middle line, and their form can be 
best understood from Text-fig. 1. 

1 R. Lydekker, Catalogue of the Fossil Reptilia in the British Musewm (Natural 
2): 1889, vol. il, p. 149. 


ORR: Hay, ‘The Fossil Turtles of North America” : Carnegie Institution, 
Publ. 75, 1908. 


012 D. UM. S. Watson—Chelonian from the Purbeck, Swanage. 


The marginals of the right side of L. 9520 are preserved, although 
they are somewhat damaged. The fourth, fifth, and sixth have a 
rounded border; from the seventh to the tenth the edge becomes more 
and more acute, a change which may be accentuated by the crushing 
the specimen has undergone. The evidence points strongly to their 
having been eleven marginals; this is, however, not quite certain 
owing to the damage L. 9520 sustained at the hands of the quarry- 
man who found it. 

The whole surface is enamel-like and polished, the ornament 
consisting of irregular depressions and ridges; the sutures between 
bones are crossed by fine striz at right angles to their direction. 


Fic. 1. Restored dorsal view of the carapace of Glyptops ruetimeyert (Lyd.). 
The bones represented by full lines are present in one or other of the Manchester 
specimens. ‘The whole carapace within the peripherals is an accurate drawing 
of L. 7017; the peripherals are added from L. 9520, which is of precisely the 
same size as L. 7017. The contour of the two anterior peripherals is taken 
from Lydekker’s figure of the type-specimen. I have inserted in the figure all 
the sulci separating epidermal shields which I have been able to make out on 
both the Manchester specimens. { nat. size. 


Plastron.—The plastron is preserved in its natural position in 
L. 9520; it is flat, and very strongly resembles that of Pleurosternum. 
The anterior end is imperfect, the bridge is long, and the free posterior 
end narrows until the posterior border ends in a distinct notch. 

There are large mesoplastra, which meet in the middle line without 
appreciably narrowing. The entoplastron was probably rather longer 
than wide; qnly a fragment of the left epiplastron remains. The 
plastron is connected with the carapace by suture of the hyo-, meso-, 


nT 


D. M. 8. Watson—Chelonian from, the Purbeck, Swanage. 313 


and hypo-plastra with the fourth to eighth marginals, and probably also 
by short and narrow buttresses; the evidence for these is that they 
have formed marked prominences on the carapace during the crushing 
which the specimen has undergone. The evidence suggests that the 
axillary buttress came down on to the first costal, and the inguinal 
buttress was fixed to the fifth and sixth costals at their junction, but 
chiefly to the sixth. 

The sulci marking the limits of the epidermal shields are ate 
obscure and only slightly impressed on the bones. So far as I have 
been able to determine them they are entered on Text-figs. 1 and 2. 
The nuchal shield is, however, quite distinct in both the Manchester 
specimens. The evidence appears to show that there were no supra- 
marginals and that the marginal shields lapped slightly on to the 
costals. On the plastron the sulci are easier to make out; there is 
a series of infra-marginal shields carried almost entirely on ‘the hyo-, 
meso-, and hypo-plastra. 


Fig. 2. Plastron of Glyptops ruetimeyeri (Lyd.). An unrestored -drawing of 
L. 9520. + nat. size. 


That the turtle I have described above is identical with Lydekker’s 
Thalassemys ruetimeyert there can be no reasonable doubt ; the contour 
of the carapace and the distribution of the epidermal shields, so far as 
they can be made out, the form and relations of the nuchal and first 
suprapygal are very similar, and with the exception of the occurrence 
of a preeneural in the Manchester specimens, such slight differences as 
there are can be easily accounted for by the fact that the type- 
specimen is rather smaller than the new specimens, and is therefore 
presumably rather younger. The plastron, containing as it does 
large and well-developed mesoplastra, at once removes the species from 


314 D. WS. Watson—Chelonian from the Purbeck, Swanage. 


Thalassemys and transfers it to the Amphichelydia or Pleurodira. The 
occurrence of infra-marginals at once puts the Pleurodira out of court. 

Hay, in his recent monograph of the fossil turtles of North 
America, published by the Carnegie Institution, retains two families 
in the Amphichelydia, the Pleurosternide and the Baénide. The 
only differences in the shells of the families are: (1) The Baénide 
have more strongly developed axillary and inguinal buttresses than 
the Pleurosternide; (2) in the Baénide the mesoplastra contract 
strongly as they approach the middle line, whereas in the Pleuro- 
sternide they retain their full width until they meet. In our species 
the mesoplastra agree with the condition characteristic of the 
Pleurosternide.. 

The buttresses cannot be well observed in the Manchester specimens, 
but judging from the inner aspect of the distal end of the left 
hyoplastron, which is visible in L. 9520, the axillary buttress must 
have been small and feeble. Therefore in this character also there 
is agreement with the Pleurosternide. The animal under discussion 
differs from Pleurosternum itself in the presence of a nuchal shield 
and in the emarginate anterior edge. 

The family only contains two other described genera, Helochelys 
aud Glyptops. Helochelys differs markedly from our form in the 
very loose connexion between the plastron and carapace, and there 
only remains for comparison Gilyptops. 

This genus was founded by Marsh for a medium-sized Chelonian 
from the Morrison, Como, or Aflantosaurus beds of the United States 
Upper Jurassic. The type species, G. ornatus, is held by Baur to 
be specifically identical with Compsemys plicatulus of Cope. Hay has 
shown that this species does not belong to the genus Compsemys, but 
represents a very distinct genus for which Marsh’s name Glyptops 
must be adopted. Judging from Hay’s beautiful figures and excellent 
description, G. plicatulus is extremely similar to our animal: with 
two exceptions the two agree exactly. The form of the carapace and 
plastron is similar, the position of the epidermal shields and the 
ornament are unusually alike; a nuchal shield is said to occur in 
G. plicatulus by Baur. The only differences in fact are these: (1) In 
our turtle there is sometimes a preneural bone. (2) There are 
two suprapygals in the English specimens; one of Hay’s specimens, 
the original of his plate vi, is stated to have only one, but his photo- 
graphic plate shows a crack or suture in a position very similar to 
that separating the first from the second suprapygal in my specimens. 
(3) In our turtle the xiphiplastra are rather more deeply notched 
than in G. plicatulus. 

The only one of these differences that is at all serious is the first, 
and as it appears that this difference is liable to occur between 
individuals of the same species, it can hardly be held to be of generic 
importance. It thus appears that 7’alassemys ruetimeyert, Lyd., 
should be referred to the genus Glypiops, and in future be known 
as Glyptops ruetimeyeri (Lyd.). It deserves to be noticed that Glyptops 
has a large range in time from the Como Beds of the Upper Jurassic 
to the Denver Beds at top of the Upper Cretaceous; its large range 
in space is thus rendered much less unhkely. 


en 


—— 


Dr. C. Davison—British Earthquakes. old 


f 


Vil.—Taur British KartaHauakeEs oF THE YEARS 1908 anv 1909. 
By Cuaries Davison, 8c.D., F.G.S. 


INCE the Swansea earthquake of June 27, 1906, no strong shock 
has visited these islands, and, with one exception, all those felt 
in the years 1908 and 1909 were comparatively shght tremors. The 
list includes 36 earthquakes, all of them originating in Scotland. 
The most important were the Dunoon earthquake of July 3, 1908, 
and the Ochil earthquake of October 20, 1908, the latter being 
the strongest shock felt in that district during the present century, 
The remaining tremors occurred in the Ochil district, and the 
great majority of them would have remained entirely unknown to 
seismologists had it not been for the interest taken in them by 
Mr. W. HB. Lindsay and Mr. T. J. H. Drysdale of . Menstrie, 
Mr. J. Dempster of Airthrey, and Dr. W. L. Cunningham of Alva. 
To the courtesy of these gentlemen I am indebted for the principal 
materials of this paper. 


1-7. Ochil Karthquakes : January 19 — June 21, 1908. 

1. January 19, 1908: 1.27 a.m.—A distinct shock, felt at Menstrie. 

On February 9, 1908, at 4.6 a.m., a shock, stronger than the 
preceding, was felt at Menstrie, but only, so far as known, by one 
observer. . 

2. May 1, 1908: 6.54 p.m.—A shock of intensity 4 felt at 
Airthrey, Alva, Dunblane, Menstrie, and Tillicoultry. The shock 
consisted of one maximum, lasted two seconds, and was accompanied 
by a loud noise like a muffled explosion. 

3. May 2, 1908: 7.5 a.m.—A shock of intensity 4, and lasting 
three seconds, felt at Airthrey, Alva, and Menstrie. At Airthrey 
the shock consisted of two concussions, connected by tremors, the 
latter concussion being the stronger. ‘The shock was preceded, 
accompanied, and followed by a rumbling noise. 

4. May 10, 1908: 12.48 a.m,—A shock of intensity 4, and lasting 
about four seconds, felt at Airthrey, Alva, Menstrie, Tillicoultry, and 
Tullibody. At Airthrey and Menstrie the shock consisted of two 
concussions, the first being much the stronger at Airthrey, and of 
about the same intensity as the other at Menstrie. Each concussion 
was accompanied by a loud noise like an underground explosion. 

5. May 10,1908: 12.58 a.m.—A slighter shock than the preceding, 
but of intensity 4, felt at Airthrey, Alva, and Menstrie. At Airthrey 
the shock appeared to be single; at Menstrie it consisted of two bumps, 
the first probably the stronger. The shock was accompanied by a 
muffled sound like that of an explosion. 

6. June 21, 1908: 38 am.—A distinct single shock felt at Alva 
and Menstrie, and at the former place accompanied by a loud noise. 

7. June 21, 1908: 4,20 am.—A slight but distinct single shock, 
felt at Menstrie. 


8. Dunoon Earthquake: July 3, 1908. 
Time of occurrence, 6.15 a.m.; intensity 4; centre of disturbed 
area in lat. 56° 6:7’ N., long. 4° 56:5’ W.; number of records 70, 
from 15 places, and a negative record from 1 place. 


316 Dr. C. Davison—British Earthquakes. 


The number of records of the time is 67. Of these 20 are regarded 
as accurate to the nearest minute, and 17 of them agree in indicating 
6.15 a.m. as the correct time. 

Notwithstanding the large number of records, for which I am chiefly 
indebted to the kindness of Mr. G. 8. Rae of Kilcreggan and 
Mr. John Robertson, F.R.G.S., of Strachur, the places at which the 
earthquake was observed are few in number. It is thus impossible 
to determine the boundary of the disturbed area with any approach 
to accuracy. Roughly it is an oval curve, 25 miles long, 21 miles 
wide, and containing about 400 square miles, with its centre 11 miles 
north of Dunoon and its longer axis directed about N. 41° E. 

At most places the shock consisted of a single series of tremors, 
its average duration being four seconds. At Strachur, however, two 
parts were felt by four out of eighteen observers, the average interval 
between them being three seconds, the first part in each case being 
regarded as the stronger. 

The sound was heard by all the observers. In 27 per cent. of the 
records it was compared to passing wagons, etc., in 29 per cent. to 
thunder, in 14 to wind, in 15 to loads of stones falling, in 4 to the 
fall of a heavy body, in 10 to explosions, and in 1 per cent. to 
miscellaneous sounds. The beginning of the sound preceded that 
of the shock in 24 per cent. of the records, coincided with it in 72, 
and followed it in 4 per cent.; the end of the sound preceded that of 
the shock in 23 per cent. of the records, coincided with it in 67, and 
followed it in 10 per cent.; the duration of the sound was greater 
than that of the shock in 18 per cent. of the records, equal to it in 
74, and less than it in 8 per cent. 

About four years before, on September 18, 1904, a somewhat 
stronger earthquake (of intensity 5) was felt in nearly the same 
district. This earthquake disturbed an area of about 564 square 
miles, the centre of the isoseismal 5 being 9 miles west of Dunoon 
and lying on the longer axis of the area disturbed by the earthquake 
of 1908, and at a distance of about 14 miles in a south-westerly 
direction from its centre.t It is thus very probable that the two 
earthquakes are connected with the same parent fault, and that the 
movement along this fault in 1904, while relieving the stress in 
the portion west of Dunoon, increased the stress in the neighbouring 
portion of the fault, and thus prepared the way for the movement 
four years later in the district to the north of Dunoon. 


9-14. Ochil Earthquakes: July 17 — October 20, 1908. 


9. July 17, 1908: 5.27 p.m.—A slight but distinct tremor, felt at 
Alva and Menstrie, and accompanied by noise. Another, but still 
slighter, shock is said to have been felt at Menstrie after 9 p.m. on 
the same day; but, as I have no direct evidence from that place, it 
should be regarded as of doubtful seismic origin. 

10. September 2, 1908: 8.16 a.m.—A single shock, of intensity 3, 
felt at Menstrie, and accompanied by a rumbling noise. 

11. September 2, 1908 : 8.51 a.m.—A single shock, of intensity 3, 
felt at Menstrie, and accompanied by a rumbling noise. 


1 Grou. Mac., 1908, Vol. V, pp. 297-8. 


Dr. C. Davison—British Earthquakes. d17 


12. October 16, 1908: 9.53 p.m.—A tremor, of intensity 4 and 
duration two seconds, felt at Airthrey, Alva, Blair Ochil (Dunblane), 
Menstrie, and Red Carr. At Airthrey the shock consisted of one part, 
at Menstrie of two prominent vibrations or bumps. The sound is 
compared to an underground explosion, a clap of thunder, or the thud 
of falling rock. 

13. October 19, 1908: 9.18 a.m.—A slight tremor, with sound, 
observed at Airthrey. The shock was also felt at Blair Ochil 
(Dunblane). 

14. October 19, 1908: 9.39 a.m. 
panying tremor, heard at Menstrie. 


A noise, without any accom- 


15. Ochil Harthquake: October 20, 1908 (Principal Earthquake). 


Time of occurrence, 4.8 p.m.; intensity 7; centre of isoseismal 6 
in lat. 56° 11-4’ N., long. 3° 47°3’ W.; number of records 59, from 
34 places, and 20 negative records from 18 places. 

This is probably the strongest of all recorded earthquakes in the 
Ochil district. The intensity was not less than 7 at Alva and 
Tillicoultry, while that of the earthquake of September 21, 1905, was 
at no place higher than 6. é 

Of thirty-six records of the time, eight are regarded as being 
accurate to the nearest minute. The average of these is 4.8 p.m., 
which agrees with the majority of estimates. 

The only isoseismal which it is possible to draw is that of intensity 6, 
and this agrees so closely with the corresponding isoseismal of the 
earthquake of September 21, 1905, that it is unnecessary to reproduce 
it. Towards the north, west, and south the two curves are almost 
coincident ; towards the east the isoseismal of the later earthquake 
falls short of the other by about half a mile. Its length is 15 miles, 
width 103 miles, and area 123 square miles. Its centre is 33} miles 
EK. 48° N. of Menstrie, and the direction of its longer axis E. 25° N. 
The magnitude of the disturbed area is unknown, but it is probably 
nearly the same as that of the earthquake of September 21, 1905, 
though slightly displaced to the south, for the shock was felt at 
several places, such as Falkirk, Polmont, and Bo’ness, which are 
from one to two miles south of the isoseismal 4 of the earthquake of 
1905, while it was not felt at Comrie, Monzie, and Crieff, close to 
the northern portion of the same curve. From the district lying to 
the south of the last-mentioned places observations are altogether 
wanting. 

At several places within the isoseismal 6 (such as Alloa, Cambus, 
Greenloaning, Menstrie, and Tillicoultry) the shock consisted of two 
distinct parts, separated by an interval of about three seconds, the 
first part being much the stronger. At other places farther from 
the epicentre one part only was observed, the effect resembling that 
caused by the fall of a heavy weight or by the passage of a traction 
engine. The average of fifteen estimates of the duration of the shock 
is 23 seconds. 

The sound accompanying the shock was heard by 92 per cent. of 


1 See Quart. Journ. Geol. Soc., 1907, vol. lxiii, pl. xxvi. 


318 Dr. C. Davison—British Earthquakes. 


the observers.. In 47 per cent. of the records it is compared to 
passing wagons, etc., in 27 per cent. to thunder, in 17 to the fall 
of a heavy body, and in 10 per cent. to explosions. The beginning 
of the sound preceded that of the shock in 33 per cent. of the records, 
coincided with it in 54, and followed it in 13 per cent.; the end of 
the sound preceded that of the shock in 19 per cent. of the records, 
coincided with it in 383, and followed it in 47 per cent.; the duration 
of the sound was greater than that of the shock.in 39 per cent., equal 
to it in 39, and less than it in 22 per cent. 


16. Ochil Harthquake: October 20, 1908, 4.13 p.m. 


Intensity 5; centre of disturbed area in lat. 56° 11:3’ N., long. 
3° 48:0’ W.; number of records 18, from 13 places. 

The boundary of the disturbed area coincides nearly with the 
isoseismal 6 of the preceding earthquake, except that it is displaced 
about half a mile to the west-south-west. The area is 15 miles long, 
101 miles wide, and contains about 128 square miles. Its centre is 
3 miles E. 50° N. of Menstrie and half a mile west-south-west of 
that of the isoseismal 6 of the preceding earthquake, and its longer 
axis is directed E. 25° N. The intensity of the shock was greatest 
(namely, 5) at Tillicoultry. The shock was merely a brief tremor, 
lasting about 14 seconds, without any prominent vibration or ‘thud’. 
The sound, which attracted but little attention, was compared to 
thunder or an explosion. 


17-386. Ochil Earthquakes: October 20, 1908 — October 22, 1909. 


17. October 20, 1908: 9.26 p.m.—A very slight shock felt at 
Airthrey and Menstrie. At Airthrey the sound and vibration began 
together, and terminated simultaneously in a thud. 

18. November 6, 1908: 4.45 p.m.—A noise heard at Menstrie. 

19. January 19, 1909: 5.28 a.m.—A shock, of intensity 4, felt at 
Airthrey, Alva, and Menstrie, accompanied by a loud sound. 

20. January 19, 1909: 5.29 a.m.—A shock, felt at Memstrie. At 
Alva two tremors were felt after the shock at 5.28 a.m., but the times 
are not known. 

21. January 28, 1909: 12.15 p.m.—A slight concussion, of 
intensity 3, felt at Airthrey and Menstrie, accompanied by a noise like 
that of an explosion underground. 

22. January 24, 1909: 12.15 p.m.—A shock, of intensity 3, felt at 
Menstrie. 

23. January 24, 1909: 2.28 p.m.—A tremor felt at Airthrey. 

24. January 24, 1909: 3.35 p.m.—A tremor, of about the same 
intensity as the preceding, felt at Airthrey. 

25. January 27, 1909: 1.40 p.m —A slight shock felt at Menstrie. 

26. February 22, 1909: 7.26 p.m.—A noise heard at Menstrie. 

27. March 19, 1909: 9.35 a.m.—A shock, accompanied by noise, 
felt at Menstrie. 

28. May 22, 1909: 3.23 p.m.—A shock, of intensity 5, felt at 
Airthrey and. Menstrie; accompanied by a sound like that of an 
explosion. 


. 
; 
{ 
{ 


Dr. C. Davison—British Earthquakes. 19 


29. May 22, 1909: 5.1 p.m.—A shock, of intensity 4, felt at 
Airthrey ; accompanied by a noise like that of a slight explosion. 

30. May 22, 1909: 5.24 p.m.—A slight shock felt at Menstrie. 

31. May 22, 1909: 8.238 p.m.—A shock, of intensity 5, felt at 
Airthrey ; accompanied by a sound lke that of an explosion, the 
sound being louder than at 5.1 p.m. 

32. October 21, 1909: 8.37 a.m.—A concussion, of intensity 4, 
felt at Airthrey, and followed by a sound like that of an explosion. 

38. October 21, 1909: 9.53 a.m.—A slight shock felt at Menstrie. 

34. October 22, 1909: 6.55 a.m.—A slight shock felt at Menstrie. 

35. October 22, 1909: 7.57 a.m.—A concussion, of intensity 4, 
felt at Airthrey, preceded and followed by a sound like that of a heavy 
body falling. 

36. October 22, 1909: 9.8 p.m.—At Airthrey, three concussions, 
separated by intervals of two and five seconds, preceded and followed 
by sounds lke those of sharp explosions. 


Origin of the Ochil Earthquakes. 


From the only isoseismal line that can be drawn of the earthquake 
of October 20, 1908, it may be inferred that the direction of the 
originating fault is about E. 25° N., which agrees closely with that 
of KE. 27° N. obtained from the earthquakes of July 23 and September 21, 
1905. The corresponding direction given by the first earthquakes of 
the present series, those of September 17 and 22, 1900, is EK. 11° N. 
They originated, however, in a more westerly region, so that it is. 
uncertain whether two faults have been in action or a single fault. 
with varying direction. 

The Ochil fault passes through or near the Hillsfoot villages, at 
which alone the slighter shocks were felt, and has a mean direction 
there of about HE. 13° N. Moreover, at several of these places 
(Menstrie, Alva, and Tuillicoultry especially) the shocks attained an 
intensity which is out of all proportion to the areas disturbed. For 
instance, the earthquake of October 20, 1908, disturbed an area of 
about 1000 square miles, while the average area disturbed by a British 
earthquake of the same intensity is about 27,000 square miles. This 
points to an extremely shallow origin for the Ochil earthquakes, and 
therefore favours their connexion with the great fault of the district. 

With regard to the hade of the fault, the seismic and geological 
evidence are at first sight apparently in conflict. In the neighbour- 
hood of Dollar, which is about four miles east of Tillicoultry, it is 
known to hade to the south. In the district in which the earth- 
quakes originate, that between Airthrey and Tillicoultry, both the 
course and hade of the fault are unknown. ‘That the originating fault 
here hades to the north is, however, clear from the relative positions 
of the isoseismal lines of the earthquake of September 21, 1905, and 
from the fact that by far the larger portion of the disturbed areas of 
several of the slighter shocks! lies on the north side of the fault. 
Either, therefore, the great fault changes hade between Dollar or 
Tillicoultry, or there is another fault in its immediate neighbourhood 


1 Such as those of September 17 and 22, 1900; July 23, October 8, December 28 
and 30, 1905; and October 20 (4.13 p.m.), 1908. 


320 Dr. C. Davison—British Earthquakes. 


which hades towards the north and which is responsible for the 
stronger earthquakes of the series. : 


Earth-shake at Stanhope (Weardale): December 2, 1909. 


An earth-shake was felt in the mining district of Upper Weardale 
shortly after 1l a.m. So far as can be judged from the small number 
of records, the disturbed area was about 7 miles in diameter and 
about 89 square miles in area. The centre is approximately in 
lat. 54° 45:1’ N., long. 2° 5:0’ W., or 3 miles west of Stanhope. The 
shock consisted of one series of vibrations, of intensity 4, and lasting 
about two seconds. The sound was compared to a heavy train passing, 
the fall of snow from the roof, or the firing of a heavy shot in a quarry. 
At Boltsburn a vibration, accompanied by a heavy rumble, was felt 
in two parts of the mine, and it was at first thought that a heavy fall 
had occurred.!. The small disturbed area, the nature and brevity of 
the shock and sound, and the disturbance in the mine at Boltsburn, 
all point to a superficial slip precipitated by the working in the mines 
as the cause of the earth-shake. 


Spurious Earthquakes. 


Tiverton district: May 25, 1909.—At about 12.55 p.m. shocks 
were felt at several places in East Devon between Honiton and 
Tiverton. Windows rattled violently, and indoors tremors were felt, 
which lasted, with short intermissions, for 15 minutes. At Uffculme 
a peculiar noise, unlike thunder, was heard for 7 minutes. At other 
places the sound was compared to the rumbling of heayy guns. That 
this was the origin of the disturbance is clear from the evident 
transmission of the waves through the air, the long duration of the 
disturbance, the nature of the sound, and from the fact that at the 
time mentioned heavy gun-firimg took place in the Channel off 
Weymouth. Honiton is 35 miles and Tiverton 50 miles west-north- 
west of Weymouth. 

Uyeasound (Shetland Islands): October 9, 1909.—A disturbance, 
supposed to be that of an earthquake, was felt at Uyeasound, in the 
island of Unst, at about 2.10 a.m. The shock, which was of intensity 5, 
consisted of two parts, separated by an interval of 9 seconds. The 
first and stronger part lasted 28 seconds, and the second 12 seconds. 
The accompanying sound resembled the noise of wheelbarrows, 
changing, about the time when the shock was strongest, to that of 
heavy wagons passing. 

So far as I can ascertain, the disturbance was noticed by only a few 
persons. The duration of the double disturbance is of course far too 
great for a British earthquake, but observers of a true earthquake 
occasionally err quite as widely in their estimates. It seems clear, 
however, that a shock so strong as that reported would have been felt 
by many persons over a wide area. It is possible that it was caused 
by thunder, which is said to have been heard the same morning. 


1 IT am indebted to the kindness of my former teacher, Professor G. A. Lebour, 
for the first records of this earth-shake. 


Reviews—Professor J. W. Gregory's Fossil Bryozoa. 321 


REVIEWS. 


I.—Cartatoctvre oF tHE Fosstr Bryozoa In THE DePARTMENT OF 
GxroLocy, British Museum (Narvurat Hisrory). THe Creraczous 
BoevozoA, Vol. Il. By J. W. Greeory, DSc, ERS, F-G-S. 
8vo; pp. xlviil, 346, 9 plates, and 75 figures in the text. London: 
printed by order of the Trustees of the Museum, 1909. 


fF\HIS volume is the third of a series by Dr. Gregory on the fossil 

Bryozoa in the National Museum at South Kensington: the first, 
comprising the forms from Jurassic strata, appeared in 1896; the second, 
published in 1899, and that now under notice contain descriptions of 
forms from Cretaceous rocks. The delay of ten years in the appearance 
of the second part of the Catalogue of Cretaceous Bryozoa has arisen 
from the retirement of Dr. Gregory from the British Museum and his 
absence from Europe for several years. In this interval the Museum 
collections have largely increased, but these later additions, with 
some special exceptions of species of systematic importance, have not 
been treated in detail in the present work, but remain over, together 
with the Cheilostomata, for description in the final volume of the 
Catalogue, which will be prepared by Mr. W. D. Lang, now in charge 
of the fossil Bryozoa in the Museum. 

At the beginning of the present volume the author contributes an 
elaborate ‘‘ Introduction to the Cretaceous Bryozoan Fauna”’, which, 
but for various obstacles, should have appeared in the previous volume. 
It is of a somewhat general character, and deals with many points of 
interest in connexion with the development of the group during this 
geological period, some of which may be mentioned. 

Yhe author is of opinion that the chief modern types of Bryozoa 
had their origin in the Cretaceous era, and that a separation line 
between the Palzobryozoa and Neobryozoa might be drawn most 
appropriately between the Jurassic and the Cretaceous. The following 
three orders of Bryozoa pass upwards from the Jurassic into the 
Cretaceous :— 

1. Trepostomata, which comprises forms with a massive zoarium 
of tubular zocecia. This order is very numerously represented in 
Paleozoic rocks, and Gregory has placed in it many Jurassic species 
and states that it is abundant in the Lower Cretaceous, but both rarer 
and smaller in the Upper, and it is continued into the Cainozoic. 
Ulrich, however, the founder of the order, holds that there is no 
evidence that the group survived later than the Paleozoic era,! and 
he relegates to the Cyclostomata many of the genera which Gregory 
has transferred to the Trepostomata. 

2. Cyclostomata. The Bryozoa of this order are very numerous, 
and they are predominant in the Cretaceous rocks; the author divides 
it into the three sub-orders of Tubulata, Dactylethrata, and Cancellata. 

3. Cheilostomata. This order makes its first appearance in the 
Jurassic, but only two species are known in this epoch; it first 


1 Zittel, Text-book of Paleontology, Kastman’s translation, p. 290. 
DECADE V.—VOL. VII.—wNO. VII. 21 


322 Reviews—Professor J. W. Gregory's Fossil Bryozoa. 


became important in the Upper Cretaceous, and it is the predominant 
group of Bryozoa in existing seas. 

Under ‘‘ Descriptive Nomenclature”’ the author defends his use of 
the term ‘gonocyst’ for a peculiar type of ovicell in some of the 
Cyclostomata on the ground that it differs from a ‘ goncecium’ in not 
being due to the modification of a single zocecium; but Dr. 8. F. 
Harmer, who has worked so extensively on the development of 
existing Cyclostomatous Bryozoa, raises the objection that in all 
Cyclostomata the ovicell is probably a modified zocecium, and therefore 
declines to accept the term proposed. Dr. Gregory further introduces 
the word ‘epizoarium’ instead of ‘epitheca’, borrowed from the 
nomenclature of corals, which is considered unsuitable as there is no 
theca in Bryozoa, and the layer is more important and varied in its 
functions in this latter group than in corals. ‘Cancelli’ is another 
term to which different meanings have been attached; by some it refers 
to aborted zocecia in dimorphic zoaria; these, however, are now named 
‘mesopores’ by Dr. Gregory, and cancelli are defined as “‘ spaces of 
interzocecial origin which remain either as simple or branched tubuli, 
or as macule, round spots or spaces, in the walls of the zoccia”’. 
But in certain cases, as in the Discoporellide (Lichenoporide) for 
example, there is great difficulty in determining whether the small 
pores are of the nature of ‘ cancelli’ or ‘mesopores’ : if the former, the 
family would be placed in the C. Cancellata; if the latter, in the 
Trepostomata ! 

Dr. Gregory then gives a general sketch of the various classifications 
proposed for the Cyclostomata by the principal authorities on this 
group from D’Orbigny onwards, and remarks that it shows an 
unusually complete divergence of opinion as to the number of’ sub- 
divisions required and as to their respective affinities. The summary 
of fifty years’ work indicates that a more complex classification is 
necessary for the fossil fauna than for the living members of the 
group. It would be possible to work out several different classifications 
of the Cyclostomata according to the values placed on the various 
characters. ‘‘Thus the nature of the zoarium, the general shape 
of the zocecium, the linear, radial, or irregular arrangement of the 
zocecia, and the solid or cancellous structure of the skeleton, might 
each be used as the primary systematic character.” Until more is 
known of the succession and geological distribution of the various 
forms, any classification of the Cyclostomata must be considered as 
experimental. That adopted by the author as the most suitable is 
based partly on zoarial and partly on zocecial characters, the former 
being used generally for the families and genera and the latter for 
the sub-orders. Three chief types of zocecia are recognized— 


(a) Simple, tubular, monomorphic zocecia with solid walls. 

(6) Zocecia monomorphic, having walls perforated by cavities—the 
cancelli. 

(ec) Zocecia dimorphic, one set being aborted to form supporting 
elements in the zoarium. 


The author is of opinion that the recent zonal collecting in the 
English Chalk by Dr. Rowe and others shows that the Bryozoa 


Reviews—Professor J. W. Gregory's Fossil Bryozoa. 323 


are often restricted in their range of distribution, and thus of value 
as zonal fossils. The view formerly held that their specific life was 
prolonged and that consequently they were of little or no use in 
marking zones was due to unreliable determinations of species. 

The Systematic Description in this volume includes first the 
Cretaceous Cyclostomata which were not treated in the first volume. 
Of these the families belonging to C. Tubulata are the Crisiide, 
Theonoide, Fascigeride, and Osculiporide, and to C. Cancellata the 
family of the Desmeporide. The families included in the order 
Trepostomata are the Cerioporide, Heteroporide, Zonatulidee, Radio- 
poride, and Cameroporide. In the sub-class Phylactolemata the 
family Plumatellide. There are also additions and corrections to 
the following families of the Cyclostomata which were described in 
the previous volume: Diastoporide, Idmonide, Entalophoride, Eleidee, 
Horneride, Petaloporide, and Clauside. 

In the descriptions of species the same lines are followed as in the 
earlier parts of the Catalogue; there is first a full Synonymy, then the 
Diagnosis, Dimensions, Distribution, Figures, and Affinities of the species. 
Then follows a List of the Museum Specimens of the particular species 
described, giving the registered number and details of form and size 
of one or more specimens included under this number; the formation, 
zone, and locality whence they come; and lastly, the name of 
the donor or of the collection to which they formerly belonged. 
Occasionally the specimens under one number are so many as to 
preclude any attempt to refer to them individually—for example, in 
“TD. 3367. More than 100 specimens ’”’. 

Dr. Gregory includes in the Catalogue descriptions or references to 
all known species of Cretaceous Bryozoa, whether represented or not 
in the Museum Collection, and altogether in this volume 308 species 
belonging to 67 genera are enumerated. But of this number the 
collection possesses specimens of only 103 species and 88 genera. 
Some of the unrepresented forms are known to be of a dubious 
character, and others may possibly be found in the recently acquired 
materials not yet fully examined; but allowing for these, it would 
seem that there are many significant gaps in the collection yet to 
be filled up. 

A very useful List of Chief Localities for Cretaceous Bryozoa 
(excluding England) and a comprehensive Bibliography are appended. 
The Subject Index and the carefully drawn up Index to systematic 
names of Bryozoa afford every facility for reference to the forms 
described. The figures in the nine plates are excellently drawn ; 
a greater number of plates to allow of further illustrating the interior 
structure of some of the forms, more particularly of the Trepostomata, 
would have been desirable. 

Students of fossil Bryozoa are greatly indebted to Dr. Gregory and 
to those who have helped him in the preparation of this and the 
previous volume on the Cretaceous forms, and they will hail with 
satisfaction the early completion of the final volume now in the 
capable hands of Mr. W. D. Lang. 


824  Reviews—Professor A. C. Seward’s Fossil Plants. 


IJ.—Fossiz Puanrs: A Text-book for Students of Botany and Geology. 
By A. C. Sewarp, M.A., F.R.S., Professor of Botany in the 
University, Fellow of St. John’s College, and Hon. Fellow of 
Emmanuel College, Cambridge. Vol. II.’ pp. xxii+-624, with 265 
illustrations. Cambridge: the University Press, 1910 (C. F. Clay, 
Manager, Fetter Lane, E.C.). Price 15s. 


W* gladly welcome the arrival of the second volume of this 

important work, and none the less so that we have waited long 
and patiently for its advent. In the first volume more than 100 pages 
are occupied in general matters introductory to a study of fossil plants 
both from a geological and a botanical aspect. These are followed by 
a chapter on the Thallophyta, embracing all the simplest forms of 
vegetative structures—Diatoms, Coccospheres, Rhabdospheres, and the 
like; Alge, Grvanella, Schizomycetes, Ovulites, Chara, and many 
others. Then come the Bryophyta, Liverworts, Mosses, etc., followed 
by the Pteridophyta, or Vascular Cryptogams, and the Equisetacex ; 
these are continued into and concluded in vol. 11. Here are also 
placed the doubtful fossil forms, the Psilotales. The Equisetites of the 
Secondary rocks and their predecessors, Phyllotheca, Schizoneura, etc., 
of Triassic and Permo-Carboniferous times, are here described and 
figured, and the [quisetales, represented by the numerous forms of 
Calamites of the Coal-measures with their wonderful stem-structures, 
leaves, and spore-bearing cones (strobilites), and Sphenophyllum, upon 
which genus the late Professor Williamson devoted so much patient 
investigation. They form the concluding chapter in vol.1i and the 
opening chapter in vol. 11. Here is also added an account of the spore- 
cone of Cheirostrobus, Scott. ‘These embrace a most interesting group 
of fossil plant-remains in which the structure has been preserved in 
a marvellously perfect manner. 

The two recent genera, Psilotum and Tmesipteris, are usually spoken 
of as members of the family Psilotaceze, which is included as one of 
the subdivisions of the Lycopodiales. It is probable, as Scott first 
suggested, that these two plants are more nearly allied than are 
any other existing types to the Paleozoic genus Sphenophyllum. 
Psilophyton, another rather obscure fossil plant from the Devonian 
and Silurian rocks of Canada, is placed near the foregoing, but its true 
botanical relations are a little uncertain. 

The Lycopodiales, like the Equisetales and Calamitez, present to. 
us plants having recent representatives and also a great and important 
series of fossil genera. ‘‘A general acquaintance with the extinct as. 
well as with the recent Lycopodiales will enable us to appreciate the 
contrast between the living and the fossil forms, and to realize the: 
prominent position occupied by this group in the Paleozoic period, 
a position in striking contrast to the part played by the diminutive. 
survivors in the vegetation of the present day” (p. 30). From the 
modern club-moss Lycopodium, the Selaginella, and the Jsoetes, all 
humble ground-plants, we pass to Arborescent Lycopodiales, Lepido- 
dendron and Sigillaria, often spoken of as ‘‘ Giant Club-mosses”’, and 


1 Vol. i appeared in 1898 (pp. vii, 452, with 111 illustrations, 12s.), and was. 
reviewed in the GrozoctcaL Magazine for May, 1898 (pp. 228-32) 


Reviews— Professor A. C. Seward’s Fossil Plants. 325 


forming by far the larger part of the forest-like vegetation of the 
Coal-measures all the world over. 

‘“The genus Lepidodendron included species comparable in size with 
existing forest trees. A tapered trunk rose vertically to a height of 
100 feet or upwards from a dichotomously branched subterranean axis, 
of which the spreading branches, clothed with numerous rootlets, grew 
in a horizontal direction probably in a swampy soil or possibly under 
water. A description by Mr. Rodway: of Lycopods on the border 
of a savannah in Guiana, forming a miniature forest of pine-like 
Lycopodiums, might, with the omission of the qualifying adjective, be 
appled with equal force to a grove of Lepidodendra. The equal 
dichotomy of many of the branches gave to the tree a habit in striking 
contrast to that of our modern forest trees, but, on the other hand, in 
close agreement with that of such recent species of Lycopodium as 
L. cernuum, L. obscurum, and other types. Linear or oval cones 
terminated some of the more slender branches, agreeing in size and 
form with the cones of the spruce fir and other Conifers or with the 
male flowers of species of Araucaria, e.g. A. imbricata. Needle-like 
leaves, varying considerably in length in different species, covered the 
surface of the young shoots in crowded spirals, and their decurrent 
bases or leaf-cushions formed an encasing cylinder continuous with 
the outer cortex. The fact that leaves are usually found attached 
only to branches of comparatively small diameter would seem to show 
that Lepidodendron, though an evergreen, did not retain its foliage 
even for so long a period as do some recent Conifers” (p. 93). 

“ By the activity of a zone of growing tissue encircling the cylinder 
of wood, the main trunk and branches grew in thickness year by 
year: the general uniformity in size of the secondary conducting 
elements affords no indication of changing seasons. As the branches 
grew stouter and shed their leaves the surface of the bark resembled 
in some degree that of a spruce fir and other species of Picea, in 
which the leaf-scars form the upper limit of prominent peg-like 
projections, which, at first contiguous and regular in contour, after- 
wards become less regular and separated by grooves, and at a later 
stage lose their outlines as the bark is stretched to the tearing-point. 
The leafless branches of Lepidodendron were covered with spirally 
disposed oval cushions, less peg-like and larger than the decurrent 
leaf-bases of Picea, which show in the upper third of their length 
a clean-cut triangular area, and swell out below into two prominent 
cheeks separated by a median groove, and tapering with decreasing 
thickness to a pointed base which in some forms (e.g. Lepidodendron 
Veltheimianum) is prolonged as a curved ridge to the summit of 
a lower leaf-cushion”’ (p. 94). 

**A fully grown Lepidodendron must have been an impressive tree, 
probably of sombre colour, relieved by the encircling felt of green 
needles on the young pendulous twigs. The leaves of some species 
were similar to those of a fir, while in others they resembled the 
filiform needles of the Himalayan Pine (Pinus longifolia)” (p. 95). 

An interesting explanation is offered of the circular linear scars 
(Ulodendron and Halonia) seen on the stem of certain Lepidodendra 
(e.g. L. Veltheimianum), and which Mr. Watson, of Manchester, has 


326 Reviews—The South Wales Coal-field. 


regarded as a branch-scar. This hypothesis is further supported by 
M. Renier, who describes a specimen of Bothrodendron from Liége 
giving indisputable evidence that the scar represents the base of the 
branch (p. 133). The structures of the spore-bearing cones and the 
scar and stem-structures of both Zepidodendron and Sigillaria are 
elaborately illustrated and clearly described by the author. 

As bearing upon the probable aquatic habit of the roots of 
Lepidodendron and Sigillaria, known by the name Stigmaria, met 
with so abundantly in the underclays of the Coal-measures, it may 
not be without interest to record that when the great water-lily lake 
in Mr. James Yates’ garden at Hampstead was drained many years ago, 
the floor was found to be carpeted with a vast interlaced mass of 
the roots of Vymphea alba and Nuphar lutea, which might have been 
easily imagined to be recent living examples of Strgmaria ficordes, their 
surfaces being covered with circular scars bounded by a raised rim 
and containing a small central pit. These scars are the bases of 
attachment of rootlets, and are often to be seen radiating through the 
shale or sandstone, once forming the muddy semi-aquatic soil on which 
these Carboniferous forest trees actually grew. 

From the forest trees of the Coal we pass to the Filicales, the 
fossil ferns whose beautiful forms are to be seen often in the roof- 
shales of our productive Coal-measures. But space does not permit 
us to dwell upon them here; they fill 300 pages, and deserve a very 
careful and full notice. Many forms met with in Oolitic shales and in 
the Wealden are recorded by Professor Seward, as well as the rich 
series from the Coal-measures. They have more than 100 excellent 
illustrations to their share. 

But we do not permanently part company with Professor Seward, for 
in his preface he announces his intention to give us a third volume to 
embrace the Ptercdosperms, other than those briefly described in the 
final chapter of the present volume, and also other classes of 
Gymnosperms. We are likewise promised some discussion on the 
fascinating subject of the geographical distribution of plants. 

The story of the past floras of the earth, interwoven as it is with 
that of its living plants, is like the Indian story-tellers’ recitals, which 
last for many days, but we promise Professor Seward—if he does 
not delay his third volume too long—we will give it as cordial 
a welcome as we have done vols. i and ii already before the public. 


II].—Memorrs oF tur GrotocicaL Survey or Encrtanp anpD WALES. 


Tur Gerotoey or THE Sourm Wares Coat-Frretp. Part X: THe 
Country azounD CarmarrHen. By A. Srrawan, Se.D., F.B.S., 
T. C. Cantritt, B.Sc., E. E. L. Drxon, B.Sc., and H. H. THomas, 
M.A.; with notes by B.S. N. Wirxrnson. 8vo; pp. vill, 177, 
with 18 text-illustrations. London, 1910. Price 2s. 


f{\HE area described in this memoir is wholly in the county of 
Carmarthen, and it is included on Sheet 229 of the colour- 
printed Geological Survey map. Two editions of this sheet accompany 


Reviews—The South Wales Coal-field. O27 


the memoir, the one with and the other without the Boulder-clay and 
associated glacial sand and gravel. ‘The drifts do not very seriously 
obscure the sequence and structure in the Paleozoic rocks which 
form the foundation of the entire area, and the Drift map will 
therefore be most useful to geologists. The price of each map is Ls. 6d. 

The geological formations include the Upper Tremadoc of the 
Cambrian, the Ordovician from the Arenig to the Upper Bala, the 
Lower Llandovery of the Silurian, the Old Red Sandstone, and 
the Carboniferous rocks up to the lower part of the Pennant Grit. 

The general structure of the area is shown on sections printed on 
the margin of the map, and here we note that there is some incon- 
sistency in the nomenclature adopted, most of the divisions being 
indicated by their stratigraphical names, such as Tremadoc Beds and 
Redhill Beds, others by zonal (graptolitic) names. We think the 
term Arenig shales would have been better than Tetragraptus Beds 
from a practical point of view. 

A most difficult country is that in the northern part of the area, 
where the Lower Paleozoic rocks are folded, inverted, and faulted, and 
shales of different ages and sometimes of similar character are brought 
into abrupt contact; but the authors have thoroughly elucidated the 
geological structure by their careful and detailed researches in the 
field, by the collection of fossils, and with the aid of Dr. Ivor Thomas 
in the Museum at Jermyn Street, of Mrs. Shakespear in the deter- 
mination of the Graptolites, of Mr. P. Lake with regard to Trilobites, 
and of Dr. C. A. Matley with Brachiopods. Most of the disturbances 
affecting the Lower Paleozoic rocks took place prior to the deposition 
of the Old Red Sandstone, and between these groups there is 
everywhere great unconformity. 

Remains of Cephalaspis and Pteraspis are recorded from the Lower 
Old Red Sandstone; and some plant-remains, Artisea and Stigmaria, 
identified by Dr. R. Kidston, have been found in the Penlan quartzite 
near Kidwelly, a rock assigned to the Upper Old Red Sandstone. 
The complex zonal divisions in the Carboniferous Limestone Series are 
described, and attention is then directed to the Millstone Grit and 
Coal-measures, which occupy the south-eastern portion of the area and 
form the western part of the main South Wales Coal-field. A small 
tract of the less productive coal-field which extends into Pembroke- 
shire is shown on the western margin of the map. The details in the 
Lower Coal Series form the most important practical part of this 
memoir. There are also notes on various economic products, including 
lead-ore, silica-stone (used for making fire-bricks), building-stones, etc. 

Among Drift deposits the occurrence is mentioned of two patches 
of sand at an altitude of more than 500 feet above sea-level east 
of Eglwys-Cymmyn. A shaft was sunk in 1906 to ascertain the 
nature of the strata, and 30 feet of sand, loam, and gravel were 
penetrated. It is noted that the sand contains an assemblage of 
minerals almost identical with that which was determined by 
Mr. H. H. Thomas in the Lower Pliocene Sands of St. Erth and 
St. Agnes in Cornwall. No fossils were obtained from the Welsh 
strata, which may have been deposited during the Glacial Period. 


328 Reviews—Transraal Gold Mining. 


LV.—TransvaaL Mrynres Deparrment, Grotogican Survey. 
: ? 


Tur Gerorosy or THE Pirertms Resr Gorp Mryine Disrricr. By 
A. L. Hatt, B.A., F.G.S. 8vo; pp. 158, with 20 text-illustrations, 
33 plates, and geological map. Pretoria, 1910. Price 7s. 6d. 


N addition to the admirable reports issued annually since 1903 by 
Mr. H. Kynaston, the Director of the Geological Survey, five 
separate memoirs on special areas, accompanied by colour-printed 
geological maps, have been issued. ‘The latest of these memoirs, 
No. 5, is the one now before us. The map represents portions of the 
Lydenburg, Zoutpansberg, and Barberton Districts, an area of about 
2600 square miles. The geological formations belong mostly to the 
Transvaal System: a great series of shales, sandstones, and quartzites, 
dolomitic limestone and chert, in ascending order, divided into the 
Black Reef Series, Dolomite Series, and Pretoria (or Lydenburg) 
Series. These rocks are generally grouped as pre-Devonian, or as 


pre-Cape rocks, their age being somewhere between Devonian and — 


Archean. Correlation is not attempted in the memoir. 

As a gold-producing district that of Pilgrims Rest ranks in the 
Transvaal next after the Rand, the output for the year 1909 
amounting to a little over £400,000 in value. Mr. Hall remarks 
that the reefs occur more especially in the Dolomite and Black Reef 
Series, and mostly as ‘‘interbedded ore sheets, and thus behave 
stratigraphically exactly like the sedimentary strata in which they 
lie”. Apart from these ‘‘ flat reefs”, there are less important ‘‘ cross 
reefs”? which strike across the formations. The author, however, 
points out that ‘‘ certain features are persistent and characterize both 
varieties of reefs. These are the essentially quartzose nature of the 
reef and the constant association with metallic sulphides, notably 
pyzites and occasionally copper ores. It is therefore probable that 
the principles controlling their formation are essentially the same”. 
He concludes that ‘‘the gold was introduced in soluble form by the 
circulation of underground waters carrying silica and iron in solution, 
the gold being precipitated mainly as the result of the reduction of 
the iron to the ferrous condition ”’. 

Full particulars are given of the strata, and of the intrusive and 
contemporaneous igneous rocks in the Transvaal System. The 
geological structure is shown in a number of sections, and the 
physical features and rock-structures are represented in a series of 
excellent photographic plates. Among these is a fine view of the 
Devil’s Window, north of Belvedere, in the escarpment of the 
Drakensberg, looking towards the low country. 


V.—Cotonsay, ONE OF tHE Hesripes: irs PLANTs, THEIR LOCAL NAMES 
AND usrEs; Lraenps, Ruins, anp Puiacze-NamES; GAELIC NAMES OF 
Birps, Fisues, rrc.; Crrmare, GrorocicaL Formation, erc. By 
Mourvocu McNertr. pp. vii, 216. Edinburgh: David Douglas, 
1910. Price 2s. 6d. net. | 
OLONSAY with its adjunct Oransay, for they are connected for 

several hours during low water, is about 12 miles in length and 

3 in breadth. As represented on Sir Archibald Geikie’s map of 


Reviews—Man as an Instrument of Research. 329 


Scotland, the joint island is formed mainly of Torridonian grits and 
flags, with Lewisian gneiss in the north, and elsewhere small areas of 
limestone, eruptive rocks, and raised beach. A more detailed geological 
sketch-map was published by Mr. W. B. Wright in 1908," based on 
field-work carried out in the course of the geological survey by 
Mr. E. B. Bailey and himself. It would have been well if this map 
had been reproduced in the volume before us, especially as the author 
acknowledges help from Mr. Bailey, who has “‘ corrected and amplified 
the chapter on Geology’’. As it is, there are no illustrations of any 
kind in the volume, although the object of the author in his chapter 
of fourteen pages on the ‘Geological Formation ’’ is to note the 
relations of the rocks to the landscape and the flora. 

The limestone, described under the name of Colonsay lmestone, 
appears to form part of the Torridonian Series, resting on flags and 
being overlain by phyllites, and in places by the granitic rock of 
Sealasaig. The author describes the various types of rock and their 
economic uses, and notes that the so-called ‘‘Scalasaig granite” is 
a diorite. 

The occurrence of boulder-clay in hollows in various localities is 
mentioned, and the effects of glaciation are noted in the rounded 
outlines and smoothed and striated surfaces of the rock-formations. 
In comparing the rocks and flora the author observes that there is 
more in common between the floras of Colonsay and those of the 
schistose and gneissose islands of the Outer Hebrides than there is 
between the Colonsay plants and those of the basaltic islands of the 
Inner Hebrides. Nevertheless, the soils on Colonsay are naturally 
influenced by the erratic materials of the Boulder-clay and by the 
Raised Beach deposits. 

The work cannot fail to be a useful guide to the visitor who is 
interested in Natural History, as may be judged from the title which 
we give in full. 


VI.—Maw as an Insrrumenr or Reszarcu. Presidential Address 
of G. W. Lampruen, F.R.S., to the Hertfordshire Natural History 
Society, April 12, 1910. 


NE would hardly accuse Mr. Lamplugh of being a wag; yet the 
instrument that comes to one’s mind more often than any other 
when dealing with scientific men is connected with boring. For 
most scientific men are so wrapped up in their little subject that 
the great world and its issues are lost sight of. We are grateful to 
Mr. Lamplugh for one sentence—‘‘ Everyone who has tried to translate 
his observations into accurate description must have felt the inadequacy 
of language.” It is a commonplace, but so true! He has, again, 
touched up those who, having large collections of material or fact, 
remain mute and neither use them nor allow others to use them to 
their full advantage. We disagree with him when he advises people 
to ‘‘record simple facts alone, without attempting to demonstrate 
their intricate relationships or to trouble himself with the technicalities 
by which these relationships are conventionally expressed”. There 


1 Quart. Journ. Geol. Soc., lxiy, p. 298. 


330 Brief Notices. 


is far too much slipshod stuff published now, and a word with a more 
experienced friend or with an intelligent editor would bring much of 
this sloppy, half-baked material into line with more mature writing, 
and render comparison and correlation much easier. The author 
does not deal with the somewhat threadbare subject of ‘‘ the pursuit 
of knowledge for its own sake”, which may be a purely selfish 
proceeding. At the present day it is more generally recognized that 
work of all kinds should be for the benefit of the community, and 
that the highest forms of research, like those of Pasteur and 
Koch, are such as are calculated to ameliorate the sufferings of 
humanity. 


VII.—Brier Noricrs, 


1. Fosstt Insecrs.—Dr. Anton Handlirsch, who has so elaborately 
worked out the history of fossil insects, is now actively at work 
describing the various new forms discovered in the rocks. We have 
before us a collection of his recent papers, and call attention to the 
following. ‘‘Ueber die fossilen Insekten aus dem mittleren Oberkarbon 
des Konigreiches Sachsen” (Mitth. Geol. Ges. Wien, 1909, ii). ‘These 
consist of Blattoid wings, and include a new genus, Apophthegma. 
Another Blattoid, Pedinodlatta, n.g., from the Franken Trias, appears 
in Abh. Nat. Ges. Niirnburg, 1910, xviii, the wing being carefully 
drawn and figured; while yet a third protorthopteron, Chalcorychus 
Walchie, is described in the author’s ‘‘ Kin neues fossiles Insekt aus 
den permischen Kupferschiefern der Kargala-Steppe (Orenburg)”’ 
(Mitth. Geol. Ges. Wien, 1909, 1). 

Dr. Handlirsch discusses the ‘‘frihjurassischer Copeognathen und 
Coniopterygiden’’ and ‘‘das Schicksal der Archipsylliden” in the 
Zoologischen Anzeiger, 1909, xxxv, and in the number of the same 
publication for May 10, 1910, gives a brief note—‘‘ Ueber die 
Phylogenie und Klassifikation der Mecopteren.” A full report of his 
lecture ‘‘ Ueber Relikten’’ will be found in the Verh. k.k. z00l.-botan. 
Ges. Wien, 1909, a lecture which dealt with many other forms 
besides insects; and a criticism of M. Fernand Meunier and his work 
on fossil insects, privately printed in 1906, may be lost sight of if not 
mentioned in these pages. 


2. CATALOGUE OF PuorocRraPHs oF GrotocicaL Supsecrs, prepared by 
the Geological Survey and Museum. 8vo; pp. 35. London, 1910. 
Price ,6d.—During the past six years the Geological Survey has 
taken photographs of objects of geological interest in the areas of 
England and Wales that were being re-surveyed on the 6 inch maps. 
In Scotland photographic work was commenced by the Geological 
Survey in 1890, and a catalogue of the photographs preserved in the 
Edinburgh Office is promised. In the present pamphlet 800 subjects 
are recorded, and they relate mostly to Cornwall, Devon, Pembroke, 
and Carmarthen. They include quarry sections, tors, raised beaches, 
stream-tin works, dykes, pillow- lavas, sand -dunes, crush - breccia, 
china-clay works, cleavage, contorted strata, etc. It is noted by the 
Director, Dr. Teall, that negatives, prints, lantern slides, or bromide 


Reports and Proceedings—Geological Society of London. 331 


enlargements can be obtained of any of the photographs on application 
being made at the Geological Survey Office in Jermyn Street, where 
prints may be seen. 


3. AnnuAL Report oF tHE Iowa Geonoeicat Survey, vol. xix, for 
1908, dated 1909.—This volume contains a full report on the coal 
deposits of the State by Mr. Henry Hinds, and a history of the coal- 
mining, which dates back to about 1840, by Mr. J. H. Lees. The 
peat deposits of Iowa are described by Mr. 8. W. Beyer. Analyses of 
both coals and peat, also bibliographies of these subjects, are given. 


4, Tue Quatiry or Surrace Waters in THE Unrrep Srares.—This 
important subject is dealt with by Mr. Dole (Water Supply Paper, 
No. 286, of the U.S. Geol. Survey, 1909) in a work of which part i 
contains the results of over 5000 mineral analyses of water from the 
principal rivers of the United States east of the Rocky Mountains. 
Daily samples of water from nearly 200 stations were collected for 
a year, united in sets of ten consecutive samples from the same stream 
and station, and the composite was then subjected to analysis. The 
analyses, giving as they do the average composition of the waters, 
the fluctuations of composition from day to day, and information 
regarding change of water-level wherever available, form the most 
complete collection of data regarding the quality of American rivers 
that has ever been published. They are on this account particularly 
valuable to railroad engineers and to managers of industrial plants 
and waterworks. 


Ra POREtS AND PROCHEH DINGS. 


GrotoeicaL Socrery oF Lonpon. 


May 25, 1910/— Professor W. W. Watts, Sc.D., M.Sc., F.R.S., 
President, in the Chair. 


The Address which it is proposed to submit to His Majesty the 
King, on behalf of the President, Council, and Fellows, was read as 
follows, and the terms thereof were-approved :— 


“To tHE KING’S MOST EXCELLENT MAJESTY. 
‘May ir preaseE Your Magszsty, 


‘* We, Your Majesty’s most dutiful and loyal subjects, the President, Council, 
and Fellows of the Geological Society of London, humbly beg leave to offer to 
Your Majesty our deepest and most heartfelt sympathy in the great and sudden 
sorrow which has fallen upon you, and most respectfully to express the grief that 
we, in common with all Your Majesty’s subjects, feel at the great loss which 
has afflicted the Nation and the Empire in the tragic death of our late beloved 
and revered Sovereign King Edward VII, in the full vigour of his services for the 
welfare of humanity and the peace of the world. 

‘« Tn the depth of our sorrow we find comfort in the assurance that the sceptre of 
our wise King passes into the hands of one who will keep ever before him the high 
destiny of the Nation, and we venture humbly to offer our fervent congratulations to 
Your Majesty on your accession to the Throne, which, under the sway of your 
ancestors, has become the greatest in the world. 

‘We trust that the knowledge of the mineral structure of the earth, for a century 


332 Reports and Proceedings—Geological Society of London. 


the special care of this Society, may continue to grow and flourish under the rule of 
Your Majesty as it has done under that of your illustrious predecessors. 

‘¢ That Your Majesty’s reign may be a long one and that it may overpass in lustre 
even those of the great Kings and Queens that have preceded you, is the earnest 
prayer of your devoted subjects.”’ 

The President then read the draft of a circular letter regarding the 
enhanced price of the Geological Survey Maps, which is to be sent 
to all institutions in the United Kingdom that are likely to be 
interested in the matter, bespeaking their support for a respectful 
representation to the Lords of H.M. Treasury. A draft of the terms 
in which this representation is to be made was also read. 


The following communications were read :— 

1. ‘* Dedolomitization in the Marble of Port Shepstone (Natal).’’ 
By F. H. Hatch, Ph.D., M.Inst.C.E., F.G.8., and R. H. Rastall, 
WiC eli Giese 

The Port Shepstone marble is shown by chemical analysis to be 
a dolomite (the molecular ratio of calcium carbonate to magnesium 
carbonate being as 3 : 2). It owes its marmorization to thermal 
metamorphism by an extensive intrusion of granite, which completely 
surrounds it and penetrates it in broad dykes. This instrusion took 
place at some time prior to the deposition of the Table Mountain or 
Waterberg Sandstone, and is therefore pre-Devonian. The dolomite 
is relegated to the Swaziland Period. 

The metamorphism of the dolomite under normal conditions is shown 
to have produced a saccharoidal marble of coarse texture, consisting 
almost entirely of carbonates; and the fact that neither periclase nor 
brucite has been produced in the normal marble is taken to indicate 
that the high-pressure conditions obtaining during the metamorphism 
precluded dedolomitization. In those places, however, where the 
dolomite contains blocks or boulders of earlier granitic rocks, inter- 
action took place between the magnesium and calcium carbonates of 
the dolomite and the silica and alumina provided by the inclusions, 
resulting in the production, in the zone of marble immediately 
surrounding the inclusions, of a number of interesting silicates of 
magnesium, calcium, and aluminium, such as olivine, forsterite, 
diopside, wollastonite, and phlogopite, as well as the oxides brucite 
and spinel. Magnesian compounds predominate, the excess of lime 
recrystallizing as calcite. A noteworthy feature is the absence 
of minerals such as garnet and cordierite, which are especially 
characteristic of low temperature metamorphism, thus indicating the 
prevalence of a high temperature during the metamorphism of the 
dolomite. 

The paper concludes with a reference to the occurrence of granite 
boulders as foreign inclusions in other limestones, and a discussion of 
the chemical reactions by which the formation of the above-mentioned 
minerals may be theoretically explained as a result of dedolomitization. 
Comparison is made with the dedolomitized Cambrian limestones of 
Assynt and Skye described by Dr. Teall and Mr. Harker, from which 
the Port Shepstone occurrence differs in the localization of the affected 
areas to reaction rims around foreign boulders, and in the part played 
by alumina in the formation of new minerals. 


Reports and Proceedings—Geological Society of London. 353 


2. ‘*Recumbent Folds in the Highland Schists.”' By Edward 
Battersby Bailey, B.A., F.G.S. 

A description is presented of the stratigraphy and structure of 
a considerable portion of the Inverness-shire and Argyllshire High- 
lands. The district considered les south-east of Loch Linnhe, and 
extends from the River Spean in the north to Loch Creran in the south. 

The following conclusions are arrived at :— 

(1) The schists of the district are disposed in a. succession of 
recumbent folds of enormous amplitude—proved in one case to be 
more than 12 miles in extent. 

(2) The limbs of these recumbent folds are frequently replaced by 
fold-faults, or ‘slips’, which have given freedom of development to 
the folds themselves. 

(3) The slipping referred to is not confined to the lower limbs of 
recumbent anticlines, and is therefore due to something more than 
mere overthrusting. It is a complex accommodation-phenomenon, of 
a type peculiar perhaps to the interior portions of folded mountain 
chains. In fact, the cores of some of the recumbent folds have been 
squeezed forward so that they have virtually reacted as intrusive 
masses. 

(4) In the growth of these structures many of the earlier formed 
cores and slips have suffered extensive secondary corrugation of 
isoclinal type. 

The Secretary read the following extracts from a letter received 
from Mr. C, T. Clough, who was unable to be present at the 
meeting :— 

‘‘T think that special attention may be called to the similarity of the effects 
produced on all the beds in the attenuated limbs of the slip-folds ; the hard massive 
quartzites, for instance, are not on the average any better preserved than the Leven 
Schists. This seems contrary to what we should expect @ priori, and it is contrary 
also to what we find in some areas affected by the post-Cambrian thrusts of the 
North-West Highlands. For instance, near Ord in the Isle of Skye, just under 
the western limb of the folded Sgiath-bheinn an Vird thrust the Fucoid Shales 
become thinner as the thrust is approached, and are ultimately almost entirely 
squeezed away from between the Pipe-Rock on the one side and the Serpulite Grit. 
on the other. 

‘* It is interesting to consider what may be the relations in age between the slips 
described by the author and the Moine thrust. The Moine Schists had certainly 
been folded intensely, and were much in the same condition as they are now, before 
the actual snap of the thrust took place. The slips of the Ballachulish district seem 
much more closely connected with the folding. This difference suggests the question 
whether, in the Moine Schists a little east of the Moine district, slips of the 
Ballachulish type may not also occur. It is certainly the case that the beds in the 
opposite’ limbs of some of the folds east of the Moine thrust show a marked want of 
correspondence. The differences have hitherto generally been explained by the 
supposition that the folds concerned were of unusually great depth, so that they 
brought into proximity beds which originally were widely separated and were formed 
under different conditions of sedimentation. It seems very possible, however, that 
the differences may in some cases be due to the presence of slips accompanying the 
folds. If such slips do occur not far east of the Moine thrust, as is thus suggested, 
we may be tolerably certain that they are somewhat older than it. 

‘* In conclusion, I should like to express my high appreciation of the perseverance 
and enthusiasm with which the author has carried out these investigations. I feel 
confident that his general conclusions may be accepted as correct, and that they mark 
a great advance in the study of the tectonics of the Scottish Highlands.” 


1 Communicated by permission of the Director of H.M. Geological Survey. 


O34 Correspondence—A. Wade. 


CORRESPONDENCE. 


THE IGNEOUS ROCKS OF THE NORTHERN END OF THE RED SEA. 


Sir,—During the year 1909 I paid two visits to the north end of 
the Red Sea. During these visits I made a careful examination 
of the igneous rock-masses forming a large portion of the Island of 
Shadwan and the hill ranges of Jebel Ksh, Jebel Um Dirra, and 
Jebel Zeit on the mainland. It is my intention to describe these 
rocks in a future paper, and to deal with their relations to one another. 
The rocks consist chiefly of soda-granites, quartz-felsites, diorites, and 
intrusive dolerites. The granites are occasionally gneissose, and in 
such case they are usually accompanied by schists, as on the Island 
of Shadwan. At other times they merge into the most perfect 
eranophyres of a very acid nature. The relations of these rocks to 
one another, and to the overlying sedimentary rocks, present problems 
of more than ordinary interest in the study of the geology of this part 
of Egypt. 

ArtuuR WADE. 


IMPERIAL COLLEGE OF SCIENCE AND ‘TECHNOLOGY, 
Rovat Cotuzce or Science, 8. Kenstncron, 8.W. 


June 8, 1910. 


THE PITFALLS FOR ELEPHANTS IN AFRICA: IN REFERENCE TO 
DEWLISH. 


Srr,—It will be remembered that the Rev. Osmond Fisher, F.G.S., 
at the Geological Society in 19047 read an interesting paper on the 
possibility of the remains of 2. meridionalis found at Dewlish having 
been snared in a pitfall. Apropos of the narrowness of the trench 
Mr. A. B. Lloyd has some remarks which may possibly be of interest 
in connexion with the subject.? ‘(On 15th (July, 1903] 1... 
camped at Kajura, and at this place had my first adventure . . . My 
nose in the air and my ears set to catch the slightest sound, while 
I strained every muscle to push myself forward through the thicket, 
when there was a sudden airy feeling underneath, and the next 
moment I found myself jammed hard and fast in a regular death-trap 
set for antelope. It was a pit about 2 feet wide at the top but 
narrowing at the bottom to a few inches, the total depth being over 
10 feet . . . These holes are dug by the natives in all the game 
country, and the mouth of the pit is usually very skilfully covered 
over with a layer of thin twigs and grass... I have seen them 
specially made for elephant.” 

R. Asptneton Burren. 


Hitpen Manor, TonsprivGe. 
June 17, 1910. 


1 Q.J.G.S., February, 1905, vol. Ixi, p. 38. 
2 A. B. Lloyd, Uganda to Khartown, pp. 96, 97, 98. 


Correspondence—J. B. Scrivenor. 300 


THE TERM ‘LATERITE’. 


Str,—The question as to the use of the term ‘laterite’ raised by 
me in the September number of last year’s Gxrotoarcat Macazine 
has figured in so many subsequent numbers that I feel some diffidence 
in asking you to publish any further remarks on the subject. I am 
indebted to Dr. Evans for an expression of his views, based as they 
are, I note, on an intimate acquaintance with the material to which 
the name was first given. ‘There is a tone of remonstrance in 
Dr. Evans’ letter that may appear justifiable under the circumstances, 
but I venture to think that this has led the writer a little astray 
from the path of argument and to lose sight of the main issue, which 
is the practicability at the present day of forcing a new definition 
of laterite on geologists and engineers, or, indeed, the right of anyone 
to do so. Dr. Eyans is more concerned on account of my opinion 
that the term is of little use as matters stand now, and falls into 
the error of crediting me with the statement that it ‘‘ must be 
abandoned”. For my part, if I treat some of the points raised 
very briefly, 1 trust it will be clear that I do so only in order to 
save your space. 

In Dr. Evans’ third and fourth paragraphs I cannot see that 
a strong case is developed against calling highly aluminous laterite 
‘bauxite’, and would refer to the quotations in my last letter, which 
appear to have been passed over. Dr. Evans is doubtless aware 
that mm DMineral Industry some Indian laterites have been referred 
to as bauxites. Perhaps ‘aluminous laterite’ as opposed to ‘ferru- 
ginous laterite’ would be more acceptable? My point is that the 
term ‘laterite’ alone should not be held to imply the presence of free 
aluminium hydroxides in quantity, because that was not the original 
significance of the term, and because that is not implied by the chief 
users of the term at the present day. 

In paragraph 5 Dr. Evans asks what could be more suitable for 
this well-characterized formation than the name Buchanan applied 
to it over a century ago. What indeed? But why attach to the 
name Buchanan gave a new definition that has no etymological 
connexion with it? 

With regard to Dr. Evans’ eighth and final paragraph, I cordially 
agree with him that the application of the rule of priority is needed 
here, but I cannot agree with him when he says that the term 
‘laterite’ has continued in use with the same significance ever since 
1807. It is surprising that the derivation of the word should be 
so completely ignored by those who make this statement. 

It will be remembered that this correspondence commenced because 
a reviewer stated that only products of weathering containing free 
aluminium hydroxides in hot, moist climates should be considered 
as laterite. The presence of these hydroxides in Indian laterites 
became generally known in 1908, but prior to that year the name 
had spread to other countries, where it was used, not always in strict 
accordance with Buchanan’s definition, for ferruginous weathering 
products that are useful in public works. No one denies the great 
interest of the discovery that Indian and other laterites contain free 
aluminium hydroxides, but it is questionable whether that gives 


306 Obituary—Robert Parr Whitfield. 


anyone the right to insist on their presence being considered the © 


leading characteristic of a product whose name indicates its resemblance 
to bricks. 

That the letters I have written may not be said to be wholly 
critical, may I add that I have lately examined a number of Malayan 
rocks with a view to determining the presence or otherwise of free 
aluminium hydroxides, and have not yet failed to obtain a positive 
result; but the work has been preliminary only, and I am not 
prepared to make definite statements as to the quantities present 
or the degree of hydration. A weathered granitic rock gaye over 
10 per cent. of alumina. A mass of kaolin afforded about 2 per cent. 
alumina. All the Malayan ‘laterites’ that I have examined yield 
a small quantity. The Malacca laterite, which is the only laterite 
in the Peninsula that I know of agreeing strictly with Buchanan’s 
definition, contains these hydroxides also. A grey clay-slate taken 
from the top of a pass far from granite outcrops and associated with 
quartzite yielded a precipitate of aluminium hydroxide equivalent 
to about ‘05 per cent. of alumina. 

I do not think for a moment that I am alone in supposing that 
the production of free aluminium hydroxides is widespread in the 
tropics, or that it is not confined to laterite in its widest sense; but 
what would be of great interest is a comparison along these lines 
of rocks in tropical and temperate regions, for it is hard to believe 
that the amount of hydroxides found in the tropics is other than 
a development of a process regulated by temperature, moisture, and 
perhaps vegetation, and that they are not being produced in smaller 
quantities in temperate climes also. 


J. B. Scrrvenor. 
Baru Gasan, 
FEDERATED ManaAy SrareEs. 
May 7, 1910. 


@ 13 eae ePAS re 


ROBERT PARR WHITFIELD. 
Born May 27, 1828. Diep Aprit 6, 1910. 

R. P. Waurrrretp, who was born in New Hartford, New York, had 
for fifty-four years been engaged in geological and paleontological 
work. He was one of James Hall’s assistants in the first State 
geological survey of Iowa, from 1856 to 1876; and he then became 
paleontologist to Professor T. C. Chamberlin’s State survey of 
Wisconsin. He laboured also for Clarence King in the Geological 
Survey of the Fortieth Parallel, contributing to the Paleontological 
Reports published in 1877. His researches were mainly on the fossils 
of the Paleozoic formations, and he dealt with all groups of Inverte- 
brata. From 1872 to 1878 he was Professor of Geology at the 
Rensselaer Polytechnic Institute, Troy, N.Y., and since 1877 he had 
been Curator of the Geological Department in the American Museum 
of Natural History.? 


1 For most-of the above particulars we are indebted to Mr. G. P. Merrill’s 
Contributions to the History of American Geology, 1906. 


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NEW SERIES. DECADE -V.. VOLES) Vil 


No. VIII.— AUGUST, 1910. 


ORIGINAL ARTICLHS. 


I.—Tue Averen Gyeiss and Morne Sepiments or Ross-SHIRE. 


By C. T. Crover, M.A., C. B. Crampton, M.B., C.M., and 
Je Ss Euerr, MeAc, D:Se: 


(WITH A TEXT-MAP.) 
Communicated by permission of the Director of the Geological Survey. 


N the centre of Ross-shire, to the west and north-west of Ben 
Wyvis, there are large intrusive masses of granite gneiss lying in 
the midst of the sedimentary Moine schists. They have a N.N.E. 
strike and extend over a tract of country about 20 miles in length, 
from Loch Luichart, near (tarve Station (Dingwall and Skye line), 
to Carn Bhren, within 3} miles of Ardgay Station (Inverness and 
Wick line). A coarse augen gneiss with large elliptical eyes of 
pink orthoclase or perthite, sometimes 2 inches long, is the principal 
rock, but a finer-grained granite gneiss also occupies considerable 
areas, especially in the region of Carn Chuinneag (see Map, Fig. 1). 
Boulders of the augen gneiss have been widely distributed by ice, and 
are common on the shores of the Moray Firth, etc. For that reason 
the ‘‘Inchbae augen gneiss”’ has long been familiar to geologists, 
though httle was known about the parent mass, except that gneisses 
of this type were exposed on the high road between Garve and 
Ullapool, particularly in the lower part of Strath Rannoch. 

Since 1900 the work of the Geological Survey has proved this 
augen gneiss to be one of a number of foliated intrusions, perhaps 
originally all parts or offshoots of a single laccolitic mass, surrounded 
by an aureole of hornfelses in which the Moine sediments are intensely 
contact-altered, and have in large measure escaped the subsequent 
dynamic metamorphism which has elsewhere over a vast area converted 
them into the great series of schists and gneisses that are generally 
known as the Moine Series. Elsewhere in all their extent from the 
north coast of Sutherland to the Ross of Mull these Moine rocks are 
paraschists and paragneisses, generally of highly metamorphic types, 
but in this aureole they retain their original bedding and clastic 
structures in singular perfection. It has been proved that when the 
Moine sediments were invaded by the granitic rocks of this region 
they were sandstones and shales of quite normal character; and much 
light has been thrown on the history of the district and the manner in 
which both igneous and sedimentary rocks acquired their metamorphic 
structures. The one-inch map of this country (sheet 93) is now in 

DECADE VY.—VOL. VII.—NO. VIII. 22 


338 Messrs. Clough, Crampton, and Flett— 


preparation, and is to be accompanied by a memoir in which the facts 
will be stated in some detail, but we propose to give a brief summar 
of the principal results with an outline of the evidence, believing that 
the conclusions are of general interest to geologists. 


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FAULTS OLD RED PELITIC SCHISTS PSAMMITIC 
SANDSTONE ETC. (SILICEGUS)SCHISTS ETC 


HITT 
HORNFELS | GRANITIC PLUTONIC BASIC PLUTONIC 
ROCKS ROCKS 


Fic. 1. Map of the Augen Gneiss District of Ross-shire. 


The relations of the chief masses of plutonic rock are indicated in 
the accompanying map (Fig. 1). It will be seen that the Inchbae 
outcrop of granite gneiss is about 53 miles long and 38 broad. 


Augen Gneiss and Moine Sediments of Ross-shire. 339 


Separated from the N.N.E. end of it by a space of 14 miles, most 
of which is occupied by Old Red Sandstone of later age than the 
granite, is the much more extensive plutonic mass of Carn Chuinneag, 
12 miles long and 4 or 5 miles broad, which includes a considerable 
variety of orthogneisses. On the south-west side of the Inchbae mass 
a group of smaller detached outcrops of augen gneiss extend several 
miles in a south-west direction as far as Loch Luichart, and are 
represented also on the west side of a big fault, striking N.N.E. on 
the west side of this loch. 

That the augen gneiss was once a porphyritie granite is proved in 
several ways. In some places the large phenocrysts of orthoclase 
preserve their original idiomorphic outlines and are surrounded by 
a granitic matrix, in which the original grains of quartz have not 
suffered granulitization. The surrounding hornfelses are invaded by 
tongues and veins of granite which have undergone very little 
deformation. At the junctions in some places, as at Kildermorie 
Lodge on the south-east side of Carn Chuinneag, the margin of the 
granite is filled with immense numbers of angular inclusions of baked 
sediment (garnetiferous biotite hornfels, ete.). Moreover, as already 
stated, there is an aureole in which certain sediments, elsewhere 
represented by the Moine schists, have the composition and structure 
of hornfelses derived from impure sandstones and  arenaceous 
shales. 

Within the intrusions various types of plutonic rock may be found. 
Towards the north-west margin of the Carn Chuinneag mass there are 
some outcrops of dark-green basic rocks, which have been proved to 
be gabbros (without olivine) and augite diorites. Others are quartz 
diorites, and there are also more acid types which correspond to 
tonalites and hornblende granites. 

In some places the basic rocks, like the porphyritic granite, are 
nearly free trom foliation, and show their original structures fairly 
well preserved; elsewhere all these rocks have been converted by 
movement after consolidation into amphibolites, hornblende schists 
and hornblende gneisses. The basic rocks occur in relatively small 
amount, and are entirely in the form of inclusions, large or small, 
surrounded and veined by the granite. The field evidence proves that 
they are earlier than the granite, and it is probable that they 
originated by the differentiation of an acid magma in much the same 
way as the basic rocks of Garabal Hill and of so many other intrusions 
of the Newer Granite Series in the Scottish Highlands and the 
Southern Uplands. 

Towards the centre of the Carn Chuinneag mass there are several 
areas of segirine riebeckite gneiss, a rock extremely rich in alkali 
felspars, with quartz and soda-pyroxenes and amphiboles. We may 
mention also the remarkable occurrence of masses of magnetite and 
cassiterite (containing sometimes nearly 16 per cent. of tinstone) on 
the north-west shoulder of Carn Chuinneag; these are accompanied by 
a peculiar dark biotite gneiss with large rounded garnets and much 
albite. ‘This mineral paragenesis is almost unique, and the origin of 
this ore-deposit is a problem very difficult of solution. The finer- 
grained granite gneiss of Carn Chuinneag, in which the egirine 


340° Messrs. Clough, Crampton, and Flett— 


riebeckite gneiss and the albite gneiss occur, is a biotite gneiss. Other 
fine-grained gneisses, which contain muscovite but little or no biotite, 
probably represent foliated aplites. 

The history of the foliation in the orthogneisses is intimately 
connected with the history of the foliation in the schists, but in the 
former there is very complete proof that this structure was developed 
after the igneous rocks were quite solid. Although sometimes nearly 
normal granites, gabbros, etc., they generally show some indication of 
deformation. In the porphyritic types the phenocrysts of quartz and 
felspar are usually less sheared than the matrix, which must con- 
sequently have been solid before the rock was crushed. The quartz 
breaks down more readily than the felspar, and every stage of 
granulitization can be made out. Where a plexus of acid veins 
permeates the basic rocks, the latter, though older, are never in 
a different state from the granites, that is to say, there is no evidence 
that the basic rocks were foliated before the granite invaded them (as 
is often seen in the Lizard district). Sometimes a complex of this sort 
has been pulled or rolled out into a banded gneiss, not unlike some 
types of the Lewisian, but both acid and basic rocks are in the same 
state, and the derivation of such a gneiss from an intrusion breccia can 
be followed step by step in the field. The crushing and consequent 
development of foliation vary considerably in intensity from point to 
point, and sometimes suddenly along certain lines of thrust or special 
shearing, which frequently strike N.N.W. But for the most part the 
foliation maintains the N.N.E. trend, which is characteristic of the 
Moine schists of this area also, and often strikes across the boundary 
with the schists. Another fact of especial significance is that the big 
masses of granite, and also the thin veins in the paraschists, are in 
a number of places foliated across their length, with the same foliation 
as marks the rocks around them.* 

The sedimentary schists that form the country rock are arranged in 
a fold with its major axis striking N.N.E., nearly parallel to the 
lengths of the granite masses, and away from the augen gneiss they 
differ in no respect from Moine schists and gneisses in other parts of 
Scotland. We may distinguish two main types—(1) the siliceous or 
psammitic schists and gneisses, with both muscovite and biotite, 
(2) coarse pelitic or semipelitic garnetiferous mica schists. Thin 
bands of zoisite-hornblende gneiss and of granulite with prisms of 
zoisite nearly an inch long are also found. The whole of these schists, 
as is well known, were originally sedimentary rocks (arkoses, shales, 
marls and sandstones), and with them occur dark hornblende chlorite 
schists which represent basic igneous masses in a state of complete 
metamorphism. In these rocks the traces of original clastic or igneous 
structures have often been effaced, though relics of pebbles of quartz 
and felspar in the psammitic gneisses locally betray their sedimentary 
origin ; the quartz pebbles are often dragged out into long ribbons. 
There are moreover in these Moine rocks no minerals of thermal origin 


1 This was first made out by Dr. B. N. Peach at the edges of the Loch Luichart 
outcrops, and was mentioned by him in the Summary of Progress of the Geological 
Survey for 1898, p. 9. 


a 


Augen Gneiss and Moine Sediments of Ross-shire. 341 


(such as andalusite) and no hornfels structures. Recrystallization and 
the development of foliation have converted them into schists and 
gneisses, typical products of regional metamorphism. 

But in certain areas around the edge of the granite, in a strip of 
country that varies in width up to about a mile, quite other types of 
rock are found. Many of them are fine-grained, flinty-looking, with 
a well-marked banding due to bedding. From the abundance of black 
mica in very small plates these rocks have a bluish leaden colour. 
They are hard and splintery, breaking in any direction, and sometimes 
contain rounded garnets as large as peas, or prisms of andalusite half 
an inch in length. When first they were encountered these rocks 
were recognized by Dr. Peach as hornfelses, typical thermo-metamorphic 
products of the action of the granite intrusion on sandy shales. 
Nothing like them had been previously seen in any part of the Moine 
country. 

In the rocks of the Southern Highlands, however, various instances 
are known where hornfelses retain in exceptional perfection the original 
characters of sedimentary rocks. On the north-west of the Ben 
Vuroch augen gneiss (a foliated granite by no means unlike that of 
Carn Chuinneag) Mr. Barrow had previously detected pyroxene 
hornfelses (cale-flintas), fine-grained, with bedding preserved. Near 
Loch Awe and in Knapdale and Islay thin bands of hornfels have 
been frequently observed at the margins of epidiorites that were once 
intrusive dolerites. 

The minetals of the banded hornfelses are quartz, felspar and brown 
mica. Very generally they contain garnet, and sillimanite also is 
common as small prisms densely clustered. Pseudomorphs of andalusite 
are found only along certain bands, sometimes in the form of typical 
chiastolite with the black cross-shaped markings, sometimes in large 
eumorphic prisms; but the mineral is always replaced by white mica 
and kyanite. Pseudomorphs after cordierite have been seen in one or 
two rocks, and there are also compact pyroxene hornfelses derived 
from the marl-bands (calcareous shales) that give rise to the zoisite 
hornblende granulites under other conditions. The fine biotite hornfels 
is often ‘spotted’ with small spots, exactly in the same manner as 
a spotted slate from the aureole of a Cornish granite. 

The banding of the hornfels is due to the alternation of lamine rich 
in quartz with others more rich in biotite. The quartzose bands often 
contain minute pebbles of rounded quartz; sometimes they have the 
structure of argillaceous sandstones, well preserved in every detail. 
On the surfaces of certain layers there are markings strongly suggestive 
of sun-cracks and ripple-marks, and others which may possibly represent 
worm-tubes. The banding is evidently due to bedding, and the rocks 
were originally fine laminated arenaceous shales. This has been con- 
firmed also by chemical analyses. Where the contact alteration is most 
intense or the rock has been very argillaceous the clastic structures, 
as might be expected, are less obvious, but they are never absent. 

It is to be noted that in the least sheared hornfels the bedding is 
generally lying at gentle angles, and over wide areas near Kildermorie 
and south of Loch Chaoruinn it is dipping at right angles to the 
general direction of the bedding and foliation in the neighbouring 


042 Messrs. Clough, Crampton, and Flett— a 


schists. In the Loch Chaoruinn district the rocks are further arranged 
in the form of a syncline, traceable by means of one of the andalusite | 
bands mentioned above. This syncline is truncated on the one hand | 
by the granite margin and on the other by the schistose rocks. The | 
pelitic mass in the areas just referred to isin the condition of hornfels, 
except along a narrow belt in contact with the granite, and at its 
outer margin next the psammitic schists, in both of which positions 
it has generally undergone considerable shearing. ‘The pelitic outcrop, 
which originally must have been a single mass of shale or sandy shale, 

is now at some points an unsheared hornfels, while at others it has 
been converted into a garnetiferous mica schist, with folds and 
foliation striking at right angles to the bedding in the hornfels. 

As we proceed outward from their centres the masses of hornfels 
in other areas also can usually be traced passing into mica schist, - 
whether we move towards the granite or away from it. There are 
many intermediate stages between typical hornfels and typical mica 
schist, one of the best marked being a fine greyish rock full of small 
micas, white and black. This may be called the stippled schist, and 
often forms a belt next to the granite. It has more mica than the 
hornfels, especially muscovite, which has developed at the expense 
of felspar. The garnets of the hornfels persist, but the sillimanite 
and andalusite disappear. The latter passes first into kyanite, and 
pseudomorphs of kyanite after chiastolite, retaining the original 
outlines and structure, though consisting only of aggregates of small 
divergent prisms, may often be seen. These we take to be illustrations 
of the efficiency of pressure in substituting that form of the silicate 
of alumina which has the highest specific gravity and least molecular 
volume. Later the andalusite crystals are greatly bent and puckered 
and converted into white mica, the large prisms being then drawn out 
into pale films that lie along the cleavage. 

The stippled schists are fissile, as their micas have a parallel 
orientation that is lacking in the hornfels. This is a new structure, 
namely, foliation. The direction of orientation often crosses the 
bedding, and as the foliation develops the sedimentary banding gets 
less evident, though still persisting. The rocks are being sheared 
and interstitial movement is taking place; the dragging out of the 
andalusite proves this and also the deformation of the quartz pebbles. 
In the other schists, which are more coarsely crystallized than the 
stippled schists, the mica plates get longer and larger; felspar 
vanishes almost completely, though sometimes a little albite makes 
its appearance. The ultimate product is a mica schist with each 
plate of mica a hundred to a thousand times larger than those of the 
hornfels. We note the operation of three processes closely connected— 
(1) interstitial movement, (2) recrystallization with orientation of the 
micas perpendicular to the directions of stress or along the planes of 
movement, (3) continued growth in size of the characteristic minerals 
of the schist. Here again chemical analyses have proved that the 
coarse mica schist was originally the same rock as the fine blue 
splintery hornfels. It is probable, however, that the extreme outer 
margin of the pelitic band near Kildermorie never was in the condition 
of hornfels, but was converted directly into mica schist. 


; 
i 


Augen Gneiss and Moine Sediments of Ross-shire. 348 


The unsheared hornfels is never found more than a mile from the 
eranite margin. Round the granite the ‘aureole’ is not continuous, 
but is broken at certain places by the intervention of shearing. It 
should also be stated that at the south-west margin of the Carn 
Chuinneag mass and around most of the Inchbae mass the granite is in 
contact with psammitic schists, in which little evidence of contact 
alteration has been detected. 

In the Moine rocks, at a distance of a mile or more from the granite, 
there is great uniformity in the character of the foliation. The 
explanation that suggests itself is that these sediments were soft and 
readily yielded to folding, while free internal movement gave full play 
to the forces of recrystallization by which schists are produced. Some 
parts of the granite mass and many parts of the hornfelsed rocks of 
the aureole were, on the other hand, more resistant to folding, and 
considerable blocks of them moved en masse and retained their original 
structures, while in adjacent portions there was much internal shearing, 
with consequent production of cataclastic structures and development 
of schistosity. 

The hornfels has been sheared decidedly less than the granite, and 
its original characters are in better preservation. The physical 
structure of these rocks seems to give them a remarkable cohesion and 
toughness under the conditions of pressure and folding that occasion 
metamorphism of the ‘regional’ type. This is no doubt due to their 
finely crystalline state, the perfect interlocking of their minerals, 
which, having grown in a solid mass, often enclose one another; and ° 
especially to the development of authigenic new felspar in the 
interstices between the sand-grains, cementing them together into 
a very rigid mass. It seems clear, from the facts known, both in 
Kaster Ross, Ben Vuroch, Knapdale, etc. (see p. 341), that fine hornfelses 
are rocks from which schists are not readily formed. 

Mr. Barrow has advanced the hypothesis’ that the Ben Vuroch 
hornfelses were preserved because they were sheltered behind a large 
resistant mass of granite. But at Carn Chuinneag the facts show 
clearly that the hornfels is a much more resistant rock than the 
granite; moreover, hornfelses occur on all sides of the granite, not 
only on the north-west, which was the lee side, but also on the south- 
east, from which the pressures came. 

It is obvious that the sediments and horntfelses were solid when 
they were sheared and converted into mica schists, and the phenomena 
observable at the junction of granite and hornfels render it equally 
clear that the igneous rocks also were thor oughly crystallized before 
the movements began. If the hornfels at the junction is quite free 
from foliation—a rare condition—the granite also shows its igneous 
structures well; but if the hornfels has passed into a mica schist the 
igneous rock is always gneissose. This is especially noticeable in the 
fine granite veins that penetrate the schists; they cut the bedding 
clearly in the banded hornfelses, and in the mica schists they have 
a foliation that corresponds with that of the schists and often crosses 
the veins from side to side. 


1 «The Geology of the Country round Blair Atholl, Pitlochry, and Aberfeldy” : 
Mem. Geol. Surv., 1905, p. 93. 


344 Messrs. Clough, Crampton, and Flett—Augen Gneiss. 


Still more convincing evidence, if that were possible, that the 
schists and gneisses of this country were developed from solid rocks 
by pressure and movement is furnished by a series of remarkable 
crush-zones that traverse both igneous and sedimentary rocks alike. 
Some of these were described by Mr. Clough in 1902,’ but the main 
facts may be recapitulated here. 

After the movements that produced the main foliation of the 
district had come to an end, and the rocks were for the most part in 
the same state as they are at present, a group of basic dykes (olivine 
dolerites) were injected along a system of fissures that have mainly 
a N.N.W. trend. Thereafter movements again set in (posthumous 
movements), but on a lesser scale and more local in their distribution. 
They folded the previous foliation in the gneisses and schists, and 
their action appears in a concentrated form along certain crush-zones 
or belts of secondary shearing, which are narrow strips running in 
various directions, but often nearly at right angles to the strike of the 
general folding in the Moine rocks. Where the hornfels is involved 
in one of these crush-zones it may be changed within a few feet into 
a lustrous mica schist. When a crush-zone passes from the schists 
into the granite gneiss, the latter also becomes highly schistose with 
a large development of new white mica. In the granite gneiss the 
vertical dolerite dykes were apparently weak rocks that easily yielded 
to pressure, for secondary shear zones rather commonly take the line 
of these dykes. In that case the basic rock assumes the form of 
a typical hornblende schist, rather fine-grained but perfectly foliated 
and completely metamorphic. The foliation in the crush-zones is 
parallel to the length of the zone, and consequently is often at right 
angles to the foliation of the Moine rocks and the granite gneiss. At 
the edges of the hornblende schist dykes a new foliation makes its 
appearance in the granite gneiss. Most perfect at the junction with 
the dyke, it fades away in a few inches. It is evidently a superinduced 
structure which masks the original foliation of the acid rock, yet it is 
often very highly developed, and thin slabs may be split off from the 
eneiss at the edge of the basic dykes with a structure which may be 
described as mylonitic at a considerable angle to the foliation in the 
same rock only a couple of feet away. 

The fine-grained structure of the dykes proves the granite to have 
been cold at the time when they were injected, and the development 
of a new foliation in the gneiss that forms the walls of the dykes proves 
equally clearly that the main foliation was already developed before 
these rocks were sheared. When the later movements supervened the 
granite compressed the dykes as a vice grips a piece of soft iron. The 
weaker metal gives way and is deformed, but before its rigidity is 
overcome the jaws of the vice also suffer. 

We believe that the granite gneiss and its aureole furnish us with 
an undoubted example of pure dynamic metamorphism. All the rocks 
involved—igneous, sedimentary, and the contact-altered hornfelses— 
were free from foliation when the movements began, and when the 
movements came to an end they were, in varying degrees of perfection, 


1 Summary of Progress of the Geological Survey for 1902, p. 150. 


a eee 


——— 


G. C. Crick—Two Chath Cephalopods. 0450 


schists and gneisses as we find them now. This implies a similar 
history for the whole Moine system of the North of Scotland. The 
age of these rocks and the period or periods of movement that 
produced the foliation are not satisfactorily established, but that the 
movements occasioned the metamorphism is sufficiently clear. There 
may be, and probably are, in the Scottish Highlands orthogneisses 
that have a different history from the Carn Chuinneag granite gneiss. 
Mr. Barrow has shown reason to believe that near Blair Atholl some 
orthogneisses have structures developed in them by pressures acting 
during consolidation.! Similar types of gneiss are believed by Dr. Flett 
to occur in the Lizard Peninsula. But in the granite gneisses of 
Ross-shire no structures have been met with that cannot be explained 
as occasioned by the action of orogenetic pressures on normal igneous 
rocks completely crystallized. 


: | 

II.—Nore on two CrpHatopops [| P4acHYDIScUS FARMERYI, N.SP., 
AND HETEROCERAS REUSSIANUM (D’ORBIGNY) | FROM THE CHALK 
oF LINCOLNSHIRE. 


By G. C. Crick, Assoc. R.S.M., F.G.S., British Museum (Natural History) .? 
(PLATE XXVII.) 


'I\HE British Museum collection has lately been enriched by two 
Cephalopods from the Chalk of Lincolnshire that seem to be 

worthy of notice; one being a new species of Pachydiscus 

(P. farmery?), the other being referable to the genus Heteroceras. 


1. PacHypiscus FARMERYI, n.sp. (P1. XXVII, Figs. 1, 2.) 

Diagnosis—Shell (internal cast) discoidal, umbilicated; greatest 
thickness at about two-fifths of the height of the whorl from the 
suture, about three-tenths of the diameter of the shell; height of 
the outer whorl about three-eighths of the diameter of the shell. 
Whorls few, exact number unknown, probably about five; inclusion 
about one-half; umbilicus not very deep, about two-fifths of the 
diameter of the shell in width, exposing the inner whorls. Whorl 
broadly oval in transverse section, a little higher than wide; indented 
to about a quarter of its height by the preceding whorl; periphery 
broadly rounded, ill-defined ; lateral area rather inflated, not sharply 
defined from the umbilical zone; umbilical zone convex, imperfectly 
defined from the lateral area. Body-chamber occupying fully one- 
half of the outer whorl; aperture not seen. Details of chambers and 
of suture line imperfectly known. ‘The surface of the outer whorl 
with about nine curved, raised, obtusely-rounded, forwardly-projected 
ribs, each being raised on the lateral area into a transversely-elongated 
node, which, in the course of the outer whorl, passes from the vicinity 
of the umbilical margin to about the middle of the lateral area, each 
of the last four or five ribs passing into a longitudinally-flattened 
tubercle at the margin of the peripheral area; the spaces between 
these principal ribs occupied, certainly on the peripheral area and 


1 «<The Geology of the Country round Blair Atholl, Pitlochry, and Aberfeldy”’ : 
Mem. Geol. Sury., 1905, pp. 98-100. 
® Published by permission of the Trustees of the British Museum. 


346 G. C. Crick—Two Chalk Cephalopods. 


‘possibly also on part ofthe lateral area, by five or six finer ribs, 
which cross the peripheral area in an orad-convex curve; near the 
anterior end of the outer whorl there is, behind each pair of flattened 
tubercles at the edge of the periphery, a similar but smaller pair at 
about two-fifths of the distance between one pair of large tubercles 
and the next succeeding pair; the inner whorl with large. widely- 
spaced obtusely-rounded nodes. 

The holotype (Figs. 1, 2) is a somewhat distorted natural internal 
cast of rather more than | one and a half whorls; the innermost whorls 
are wanting. The fine ribs are specially visible on the peripheral area 
of the first and last portions of the outer whorl, but the surface of the 
specimen is not. sufficiently well preserved to show if these were 
continued over the lateral area. The surface of the fossil generally is 
too imperfectly preserved to show the course of any of the septal 
sutures, although septa appear to have been present throughout fully 
two-thirds of the outer whorl. The specimen, which now forms part 
of the National Collection [B.M. No. C. 12,220], was collected by 
J. R. Farmery, Esq:, after whom the species is named. Its measure- 
ments are: greatest diameter, 91°5 mm. (100) ; width of umbilicus, 
37°5 mm. (41); thickness of outer whorl, 27°5 mm. (80); ‘height of 
outer whorl, 34°75 mm. (38) ; ditto above preceding whorl, 23 5mm, 
(25-6). 

Horizon and Locality.—Turonian, zone of Hotaxtor planus: Boswell, 
near Louth, Lincolnshire. 

A finities and Differences.—The specimen. tool resembles Schliiter’s 
Ammonites auritocostatus,! but that species, recorded by its author 
from the mucronata beds (Senonian) in Hanover, is more narrowly 
umbilicated than the English form; the specimen from near Darup, 
‘Westphalia, which Schliiter® figured and doubtfully referred to this 
species, but has been named “by A. de Grossouvre® Pachydiscus 
ambiguus, and recognized by him in the Middle Campanian at Tauillard 
(Charente), France, is not only more narrowly umbilicated but a 
more compressed shell, the lateral area lacking transyersely-elongated 
nodes, whilst between each pair of nodes ‘at. the margin of the 
periphery there are two or three fairly - prominent simple ribs 
extending uninterruptedly from the umbilical margin over the sides 
and the peripheral area. It is also more widely umbilicated than the 
example from the neighbourhood of Gan, near Pau (Basses-Pyrénées), 
that Seunes* referred to Schliiter’s species, but which Grossouvre? 


1 C. Schliter, pening. cur Kenntniss der jiingsten Ammoneen Norddeutschliands, 
1867, p. 20, pl. i, fig. 2 (Ammonites Proteus, a name preoccupied by d’Orbigny). 
C. Schliiter, “ Qephalopoden der oberen deutschen Kreide,”’ pt. ii: Pal@ontographica, 
Bad. xxi, Lief. ii, 1872, p. 70, pl. xxii, figs. 4, 5 (not 6, 7 = Pachydiscus ambiguus, 
A. de Grossouyre). 

? C. Schliiter, ‘* Cephalopoden der oberen deutschen een pt. ii: Paleonto- 
graphica, Bd. xxi, Lief. ii, 1872, p. 70, pl. xxii, figs. 6, 

3 A. de Grossouvre, Mém. Carte géol. détailide de la Fbhie : Recherches sur la 
craie supérieure. Lop ii: Les Ammonites de la craie supérieure, 1893, p. 198, 
pl. xxix, fig. 3. 

4 J. Seunes, Recherches géologiques sur les terrains secondaires et V éocéne infcrieur 
de la région sous-pyrénéenne du sud-ouest de la France (Basses-Alpes et Landes), 
1890, p. 239, pl. vil, fig. 4 

> A. de Grossouvre, op. cit., p. 197. 


G. C. Crick—Two Chalk Cephalopods. B47 


identifies with Pachydiscus Sturt (Redtenbacher)' from the so- 
called Gosau Beds at Muthmannsdorf, Austria, a species which 
he also records from Mas de Blas Giner, near Alcoy (province of 
Alicante), Spain; in all cases in the Upper Senonian. 

The Lincolnshire specimen, although belonging to this group of 
forms, is easily distinguished by its wide umbilicus. Occurring at 
a lower horizon than the other species mentioned, namely, in the zone 
of Holaster planus, one would naturally expect to find a more widely 
umbilicated form. 


2. Herrroceras REUssIANuM (d’Orbigny).? (PI. X XVII, Fig. 3.) 


The specimen which seems to be referable to d’Orbigny’s genus 
Heteroceras was obtained by the Rev. C. R. Bower from the Holaster 
planus-zone at North Ormsby, Lincolnshire. In this genus there is 
a turreted portion as in Zurrilites, but the terminal portion of the 
shell is bent into the form of a hook. The present specimen 
(Fig. 3) appears to be a portion of the terminal hook of an example 
lying upon, and with one end partially imbedded in, a small block of 
chalk, the portion on the right-hand side being the anterior or apertural 
end. Close to this end of the hook there is a portion of a whorl of 
a turreted Cephalopod (marked a) that possibly originally belonged 
to the same specimen as the larger fragment. The hook, which has 
a total length of about 110mm. as measured along the median line 
of its periphery, does not lie quite in one plane, but has a double 
curvature; this character is exhibited more especially by the posterior 
portion of the hook that is only partially exposed and is shown on the 
left-hand side in the accompanying figure, this limb being apparently 
the one by which the hook was attached to the turreted portion of the 
shell, and therefore the younger portion of the hook. ‘he transverse 
section of the last portion of the shell (the part on the right-hand side 
in the accompanying figure) is a compressed oval, the ventro-dorsal 
and transverse diameters being 25 and 17 mm. respectively ; the cross- 
section of the other limb cannot be ascertained as it is partially 
imbedded in matrix, but the greatest width exposed is about 25 mm. 
The younger portion of the hook, excepting the inner or antisiphonal 
area, is ornamented with simple, rather oblique, and somewhat 
irregularly- -placed ribs, which pass uninterruptedly over the periphery, 
where they are about 2mm. apart; at irregular distances some of 
these are thicker than the rest and roughened and may originally have 
been produced into several small spines, but they are now too much 
abraded to state this with certainty; the later portion of the shell 
seems to have been ornamented with similar fine ribs, but at irregular 
intervals some of the ribs are greatly thickened on the outer portion 
of the lateral area and on the periphery of the whorl. The septa 


1 A. Redtenbacher, ‘‘ Die Cephalopoden der Gosauschichten ’’: Abh. d. k. k. geol. 
Reichsanst., Wien, Bd. v, 1873, p. 129, pl. xxx, fig. 10 (Scaphites Sturt). 

2 Hamites reussianus a Orbigny, Prod. de Paléont., vol. ti, 1850, p. 216.: This 
species was placed by Pictet and Campiche in the genus Anisocer as; by Schliter in 
the genus Heteroceras; and by Geinitz, Roemer, and Fritsch in the venus FHelicoceras. 
For 3 synonymy and references, see H. Woods, Quart. Journ. Geol. Soc. ., vol. lii,; 1896, 


pp. 74, 7d. 


348 G. C. Crick—Two Chalk Cephalopods. 


cannot be seen; possibly the whole of this fragment was occupied by 
the body-chamber. 

The specimen greatly resembles the large example of Heteroceras 
reussianum (d’Orbigny) from. the ‘Scaphiten-Plainer’ near Oerling- 
hausen, in the Teutoburger Wald, N.W. Germany, figured by Schliiter,’ 
who states (op. cit., p. 109) that this fossil is one of the most 
characteristic fossils of the ‘Scaphiten-Pliiner’. Although there are 
only obscure indications of the periodical spiny ribs such as are 
represented in Schliiter’s figure, the fossil otherwise so closely 
resembles that figure, that it is here referred to the same species. 

From England? this species has been recorded from the Chalk Rock 
(zone of Holaster planus) of Bedfordshire (Luton Railway Cutting,* 
and near Dunstable *); Hertfordshire (Hitchin ;° Preston, near 
Hitchin ;* Boxmoor, near Hemel Hempstead ;7 and Clothall, south- 
east of Hitchin *); Berkshire ° (Cuckhamsley and Basildon 1) ; 
Oxfordshire (Aston Hill, near Aston Rowant;’* and doubtfully from 
Chinnor Hill’*); from the zone of Holaster planus in Buckingham- 
shire *; from the same zone at Dover’®; and from the same horizon i im 
Hampshire. mA 


EXPLANATION OF PLATE XXYVII. 
Pachydiscus farmeryi, G. C. Crick. 


Fic. 1. Lateral aspect of the type-specimen ; the finer peripheral ribs are shown on | 


the right-hand side of the figure. Turonian, zone of Holaster planus : 
Boswell, near Louth, Lincolnshire. Original in the British Museum 
(N atural History), register No. C.12,220. About four-fifths nat. size. 

,, 2. Peripheral aspect of the same, showing the pairs of elongated nodes at 
intervals on the peripheral area ; the finer transverse lines between 
succeeding pairs of nodes are visible in the upper part of the figure. 
About four-fifths nat. size. 

Heteroceras reussianum (d’ Orbigny). 

», 3. Small block exhibiting the terminal hook, and (at a) the impression of 
a small portion of the turreted part, of a specimen. ‘Turonian, zone of 
Holaster planus: North Ormsby, Lincolnshire. Original in the British 
Museum (Natural History), register No. C.12,118. About two-thirds 
nat. size. 


' C. Schhiter, Puleontographica, Bd. xxi, Lief. v, 1872, pl. xxxii, fig. 19. 
2 For a of foreign localities, see H. Woods, Quart. Journ. Geol. Soc. » vol. lit 
(1896), p- 
2 dale Wad Oe Ohy jo (Os Ne 5 . Jukes-Browne, Cretaceous Rocks of Britain 
(Mem. Geol. Surv.), vol. 1, Tie Upper Chalk of England, 1904, p. 228. 
4 H. Woods, op. cit., p. 75. A. J. Jukes-Browne, op. cit., p. 228. 
> H. Woods, op. cit., p. 75. 
6 A. J. Jukes- Browne, op. cit., p. 228. 
7 Jbid., p. 228. : Thia., p. 228. 9 Ibid, p. 470. 
ON ale Woods, op. cit., p. 75. 
1 ©. P. Chatwin & T. I vithers, Proc. Geol. Assoc., vol. xx, pt. v, March, 1908, 
407. 
Pie A. J. Jukes-Browne & H. J. Osborne White, Geology of the Country around 
Henley-on-Thames, etc., 1908 (Mem. Geol. Sury. England and Wales, expl. of 
sheet 254), p. 54. ‘ 
13 A. J. Jukes-Browne, op. cit., p. 213. 
14 Ibid., p. 470. 
15 A. W. Rowe, Proc. Geol. Assoc., vol. xvi, pt. vi, February, 1900, p. 366. 
16 A. J. Jukes-Browne, op. cit., p. 65. 


eS ee 


Grout. Mac. 1910. Puate XXVII. 


Chalk Ammonoids from Lincolnshire. 


——— 


H. L. Hawkins—Ambulacral Structures in the Holectypoida, 349 


I11.—Somr AmBpunacRAL STRUCTURES IN THE HOLECTYPOIDA. 


By Herzsert L. Hawxins, B.&c., F.G.S. 


FJ\HE phenomena of ‘plate-crushing’ in the course of the growth 


of the ambulacra of the regular Echinoids have for many years 
been utilized for purposes of classification of those forms, but the 
similar features which exist among some of the irregular types have 
not been studied in such detail as to render them systematically 
useful. It is with a view to showing that the structure of the 
ambulacra in one group of the Echinoidea Jrregularia can be relied 
upon as an index ofthe relationships of the various genera, that this 
note has been written. It makes no pretence at completeness, as the 
material and time available have not been sufficient to allow of an 
exhaustive study. But the results of those observations that have 
been made seem to indicate that among the Holectypoida it should 
be possible, with the aid of zonal collecting, to trace genetic series 
among the various species, and perhaps to bridge the gulfs existing 
between the genera, by a study of their ambulacral plating. 

That this method could be applied to the Holectypoida only 
seems certain. Among the Spatangoida the ambulacra are composed 
throughout of simple primary plates, varying greatly in shape and 
size, but not complicated by the development of demi-plates, except 
in the immediate vicinity of the peristome. The petaloid portions of 
the ambulacra in the Clypeastroida may exhibit the phenomena of 
‘ plate-crushing ’, but I have only observed demi-plates in one 
specimen of a Clypeaster from the Miocene of Southern Europe. In 
any case, when the ambulacrum is traced beyond the limit of the 
petal, it is found to be composed of polygonal primary plates 
throughout its length. 

In the Holectypoida, a group which is regarded as being the order 
of the Irregularia least removed from the regular type, the complexity 
of the ambulacral plating is often comparable with that in the simpler 
forms of the Diademoida. Among the latter group, in the more 
primitive sub-order of the Diademina, the ambulacrals are united in 
sets of three to form one compound plate, and a triple arrangement 
also obtains in the plates of the Holectypoida. But the arrangement 
of the component parts of a complete ambulacral in such a genus as 
Conulus, although in parts similar in appearance to that which is 
found in forms allied to Ardacia, is arrived at in a strikingly different 
manner. So regular is the order in which the plates become crushed 
into demi-plates that it is possible to regard the series of three which 
ultimately form a compound plate as being made up of three entirely 
different kinds of plate. 

Before the region of crushing is reached there is no visible difference 
between the members of the simple row of primaries (see Fig. 2, 
Pygaster), but when the modification sets in, these plates succumb 
with surprising regularity, always in a definite order. It will be 
convenient for the purpose of this note to designate the individuals 
of the series of three plates by the letters a, 4, ¢ (see Fig. 1). These 
individual plates bear the following relation to one another: plate a 
will remain a primary throughout the entire ambulacrum, and will, 


350 HH. L. Hawkins—Ambulacral Structures in.the Holectypoida. 


as it were, include the remnants of the others; plate d will retain 
its primary character later than plate e, and when both of these 
plates have become reduced, 6 will be constantly larger than ec. The 
compound plate resulting from the maximum of crushing is composed, 
counting from its adapical suture to its adoral margin, of these three 
plates in the order J, ¢, a; 6 and ¢ being let in to the adapical portion 
of a. This feature is explained by the diagram, Fig. 1. Irregularities 
occur at times in this sequence of events, more especially near the 
peristome, but in those cases of marked departure from the scheme 
that I have noticed there is always a tendency for the regular order 
to be resumed as soon as possible. The specimens that conform to 
this outline scheme are, however, very largely in excess of those 
which exhibit modifications, and I feel confident in regarding this as 
the typical ambulacral formation among the Holectypoida. 


Fie. 1. Generalized diagram illustrating method of plate-crushing in the 
Holectypoida. 


? 


The feature of this ‘ plate-crushing’ which seems to be most 
valuable for making a study of genetic affinities is that the point at 
which the demi-plates first appear varies in a constant series. In 
a suite of twenty specimens of Conulus albogalerus, the plate of set e, 
which first becomes modified, was always No. 9 (counting from the 
latest formed plate of set a), both in the five ambulacra of each 
individual and in the whole series of specimens. ‘This fact seems to 
show that the position of the first ‘ crushing-point’ may be relied upon 
as a specific criterion. An examination of several specimens of other 
species of Conulus confirms this belief. Further generalizations must, 
however, be postponed until a critical examination of certain forms has 
been undertaken, and the resulting diagram analysed. 

The four genera here discussed are Pygaster, Holectypus, Discovdea, 
and Conulus. Species of all of these genera may be found in great 
abundance at various horizons in British Jurassic and Cretaceous rocks, 


Kaeo sesn: + 


H. L. Hawkins—Amobulacral Structures in the Holectypoida. 351 


and so material for a genetic study of the forms merely awaits the 
accumulation of sufficient zonally-collected specimens. 

Pygaster, Agass., first appears in the Upper Lias, and is possibly 
represented in the Middle Cretaceous by P. truncatus, Agass. The 
genus is, however, practically confined to the Jurassic Period. 

Holectypus, Desor, originates in the Inferior Oolite, and continues 
into the lower part of the Upper Chalk (Z. serzalis). 

Discoidea, Gray, is an essentially Cretaceous genus, commencing in 
the Lower Gault and disappearing at about the same horizon as does 
Holectypus. 


PYGASTER HOLECTYPUS DISCOIDEA CONULUS 
SIACROCYPHUS SERIALLS FORGEMOLLI ALBO-GALERUS 


Fie. 2. Comparison of the plate-crushing in four Holectypoid genera. 


Cenulus, Leske, is another purely Cretaceous genus, first met with 
in the Upper Gault and persisting to the top of the Upper Chalk. 

Considered in this order (that of their appearance in time), these 
four genera exhibit a fairly uniform series. Pygaster, with its 
periproct but slightly removed from the apex, and its well-developed 
jaws and external branchie, shows marked affinities with the Regulares; 
and Conulus, with a marginal periproct.and probably no true jaws 
(when adult), is the most remote from the regular condition. 


: 


352 H. L. Hawkins—Ambulacral Structures in the Holectypoida. 


The four species I have chosen for the purpose of the diagram are, 
as far as I could obtain specimens, representative of the later specific 
developments in all four genera. The specimens utilized are all 
approximately adult. 

Pygaster macrocyphus, Wright (the only traceable co-type of which 
is in the South Kensington Museum), is from the Kimmeridge Clay 
near Boulogne. Although the adapical regions of the test are con- 
siderably broken, enough of the ambulacra can be examined to show 
that considerably more than sixty consecutive ambulacral plates, 
counting from the apex, in each ray are simple primaries. Apparently 
the development of demi-plates does not commence until a region 
about half-way between the ambitus and the peristome. Examples of 
P. semisuleatus and P. umbrella which I have examined show at least 
an equal postponement of the ‘crushing-point’, but it is not often 
that specimens suitably preserved to show the plate sutures are met 
with among the Jurassic forms. 

Holectypus serialis, Deshayes, from the Turonian of Algeria, is 
perhaps the latest member of the genus known. Two specimens in 
my collection show the plate sutures very clearly, although the 
diameter of the larger example is only 15mm. The first indication of 
‘plate-crushing’ occurs (of course, in set ¢) at plate 39, where this 
primary becomes wedge-shaped, reaching the median suture by a very 
narrow strip. Plate 42, the next of the ¢ set, is definitely a demi- 
plate, and plates 41 and 43 meet round it along the median line. 
Whenever the plates of the ¢ set are seen as the ambulacrum is traced 
towards the peristome, they are found to be demi-plates, whose 
extension towards the median suture becomes reduced the nearer they 
are to the mouth. Plate 47 is the first member of set 6 to show 
a cuneiform shape, and by the time plate 56 is reached this set also is 
represented by demi-plates, and the median ambulacral suture is entirely 
formed by the large primaries of set a. In H. depressus from the 
Lower Oolites, the crushing of the plates of set ¢ is postponed beyond 
plate 50, and that of the plates of set 4 yet further from the apical 
system. ‘hus in earlier Jurassic times this genus would appear to 
have been similar to Pygaster in the structure of its ambulacra, but to 
have developed in the course of time a far more complex condition 
than was ever reached by the latter genus. 

Discoidea Forgemolli, Coquand, from the ? Senonian of Algeria, 
exhibits the phenomena of ‘ plate-crushing’ in a degree advanced from 
that in Holectypus. Plates of set ¢ begin to appear compressed and 
wedge-shaped at number 33, and the reduction in size of the plates of 
set b is accelerated to such an extent that while plate 36 (set ¢) is but 
hardly separated from the median suture, plate 35 is already cuneiform. 
In a D. cylindrica from the Lower Chalk the first indication of crushing 
in set ¢ appears at plate 39, and in set 4 at plate 41. So that im this 
earlier form the proportionate rate of crushing of the two sets of plates 
is similar to that in D. Vorgemolli, but the point at which it commences 
is postponed by six plates. It will be noticed that in the case of 
D. cylindrica the ‘ crushing-point’ is identical with that in Holectypus 
serialis from a newer horizon. ‘There is thus some overlapping in this 
feature among the various genera, but in the fully specialized members 


Grou. Mac. 1910. Puate XXVIII. 


hi i} iif 

q cy . 

Pan jie th 
{Fe 


T. O. Boswortn photo, 
Wind-eroded Rocks on the Coast of Mull. 


T. O. Bosworth—Wind Erosion in Mull. 303 


of each genus the distinction holds good. The very fact of the over- 
lapping would tend to confirm the supposition that this ‘ plate-crushing’ 
is of genetic value, and that parallel development takes place among 
the several genera. 

In the case of Conulus albogalerus, Leske, from the Upper Senonian, 
the crushing is markedly earlier in its origin. So much so that, 
whereas in Holectypus and Discoidea the ambulacra on the adapical 
surface of the test seem almost entirely composed of primaries, in 
Conulus the great bulk of each ambulacrum is built of crushed plates. 
The first indication of crushing in set ¢ appears at plate 9, and in 
set 6 at plate 20. But while in set ¢ the plates become small demi- 
plates inserted in the outer angles of the others by the time plate 15 
is reached, in set 4 the primary character lingers on until plate 42. 
Thus the greater part of the median ambulacral suture is made up of 
the edges of plates belonging to sets a and b. This perpetuation of the 
primary plates in set 6 would appear to be a special feature developed 
in the course of evolution of the genus, for in C. subrotundus from the 
Cenomanian, while the plates of set ¢ begin to diminish in size at 
number 12, and those of set 6 at number 20, the latter set of plates 
becomes definitely separate from the median suture at number 43. 

There seems, therefore, to have been in the history of the development 
of the Holectypoida a tendency to introduce ‘plate-crushing’ in the 
ambulacra to an increasing extent. As this feature may very likely be 
connected with two other noticeable. characters of the progressive 
development (increase in the height of the adapical surface of the test 
and narrowing of the ambulacra), it should serve as a useful index to 
the genetic relationships of the various genera and species. As I have 
not sufficient material to investigate the ambulacral structures of the 
other genera of the order, nor the opportunity of collecting sufficient 
numbers of specimens for working out specific relations within the 
various genera, I have thought that the above indication of the 
possibility for important evidence on this branch of evolution might 
perhaps induce others, more favourably situated in these respects, to 
continue and amplify the study. 


TV.—Wuinp Erosion on tHe Coast oF Mutt. 
By T. 0. Bosworrn, B.A., B.Sc., F.G.S.1 
(PLATES XXVIII AND XXIX.) 


(J\HE Ross of Mull is a comparatively low-lying peninsula exposed 
to the storms and swept by gales from the Atlantic. On these 
rocky shores are occasional stretches of sand which frequently have 
been driven inland, forming dunes and patches of blown sand at 
intervals around the coast. Sometimes the sand is forced up the cliffs- 
and deposited more than 100 feet above the sea, and there are places 
in the centre of the peninsula where the blown shell-material is quite 
a noticeable constituent in the soil. 
In one instance, the peculiarities of which are here to be described, 


1 With permission of the Director of the Geological Survey. 
DECADE V.—VOL. VII.—NO. VIII. 23 


354 T. O. Bosworth— Wind Erosion in Mull. 


the dune formation is accompanied by considerable rock erosion. On 
the north coast 33 miles north-west of Bunessan, and half a mile west 
of the bay called Camas Tuath, is a smaller bay marked on the 6-inch 
map as Traigh na Margaidh. It is one-sixth of a mile wide at the 
mouth and reaches thence one-fifth of a mile inland. In this inlet, 
which is bounded by granite cliffs, there is a wide stretch of white 
sand, which, followed inland, becomes a mantle of blown sand spreading 
over and banked up against the granite rocks. This sand is decidedly 
more worn than that on the beach, and the sorting of the grains is 
more complete. Magnetite grains are abundant in it; and from one 
sample 5 per cent. by weight was easily extracted with a magnet. 

The granite is coarsely crystalline and of homogeneous texture, 
without any parallelism of minerals or any sign of shearing. The 
joint planes here are vertical with directions 45° W. of N. and 
30° E. of N. 

The wearing of the rocks on the sides of the bay and on the 
hummocky masses more or less buried in the sand indicate within 
the inlet a prevalent N.N.W. wind, straight up the bay and up 
the ‘slack’ which is its landward continuation. The crests of the 
elongated mounds of sand which have formed on the lee side of the 
hummocks also have this trend, and the crests of the ripples are at 
right angles to it. 

The hummocks are elongated in the direction about 15° W. of N. 
They are often undercut and worn to a somewhat conical shape with 
the point more or less sharpened and facing the wind. (See 
Pl. XXVIII, Fig. 1.) On these windward ends smooth hollows 
have been formed in the felspar, and deep narrow-mouthed pits 
where mica has been, while the quartz stands out as tiny smooth 
knobs sometimes mounted on diminutive undercut stalks of pink 
felspar, like a minute collar stud. (See Pl. XXVIII, Fig. 2.) 

The surfaces of the rocks and hummocks are highly polished and 
curiously corrugated, being worn into regular ridges and furrows. 
(See Pl. XXIX, Fig. 3.) From the windward ends of the hummocks 
these radiate as from a focus, but on the flat surfaces they are more 
strictly parallel, trending N.N.W. The ridges vary considerably in 
dimensions; commonly they are about a quarter of an inch apart, and 
the furrows say one-tenth of an inch deep, but in some cases the 
ridges are an inch apart and the furrows one-third of an inch deep, 
and in others there are as many as ten ridges to the inch. Some- 
times there are major and minor corrugations. The furrows are 
formed in felspar, but each ridge begins abruptly at its windward 
end with a quartz crystal worn into a smooth polished convex cap 
and often almost worn away. ‘The remainder of the ridge consists 
mainly of pink felspar sheltered from destruction by the quartz, and, 
unless some more quartz is encountered, the ridge dies out in the 
course of an inch or two. Both quartz and felspar are so highly 
polished that they have a sub-pearly lustre. 

Loose boulders of granite, that probably have not lain long in place, 
are corrugated like the rocks, and a loose block of basaltic rock from 
a neighbouring dyke was seen to be fluted in a somewhat similar 
way, a relatively large crystal of ferromagnesian mineral forming the 


Grou. Mac. 1910. PLATE X XIX. 


1. O. Bosworth photo. 


Wind-eroded Rocks on the Coast of Mull. 


T. O. Bosworth— Wind Erosion in Mull. 359 


windward end of each little ridge. A few wind-cut pebbles also lay 
upon the sand. . i 

_ Such surfaces as these, which thus at every point bear record of the 
exact direction of the eroding sand drift, can only be formed in places 
where the direction of the wind is constant. Probably this condition is 
here almost perfectly realized; the direction of the air currents being 
determined by the shape of the bay, so that changes in the wind 
outside affect only their intensity and not their direction. The 
bearings quoted here are from measurements on one particular 
hummock ; they vary somewhat from place to place in the bay, and 
in the arm, which branches off to the east, the dunes and corrugations 
are from west to east. 

Higher up among the rocks at the south end of the bay is a slightly 
inclined 9 foot sheet of mica trap which projects out from the rock 
side forming a bench whose foot is reached by the banked-up sand. 
The front of this sill is nearly vertical and is divided up by the joints 
into some four or five layers of rectangular blocks. The blown sand 
strikes obliquely against this wall of rock, and at one place every block 
has had its front top windward corner eroded away (Pl. XXIX, 
Fig. 4). In some cases several small facets have been cut, meeting in 
fairly sharp edges. A few of the facets are furrowed, each minute 
furrow beginning in a ferromagnesian mineral, but generally the corner 
surfaces are instead almost covered with small pittings, and are con- 
spicuous on account of their peculiar colour. Normal weathering gives 
the rock a red-brown rough surface, but these corner surfaces appear 
from a slight distance of a dark-purple plum colour, to which a little 
polish has added the appearance of bloom. The purple effect is due 
to the steel black colour in the pittings. It is removed to some 
extent by acid yielding a solution containing iron. Possibly it is due 
to a thin film of fine magnetite dust imparted by the magnetite grains 
in the blown sand. 


_ Thus wind-blown sand is here ever at work on the rocks in advance 
of the waves, lengthening the bay at its landward end, and so playing 
some small part in the coast erosion. 


EXPLANATION OF PLATES XXVIII AND XXIX. 


Prats XXVIII. 


Fie. 1. Two of the small hummocks, conical in front, with points towards left-hand 
lower corner of picture. Both are about 18 inches high. 

_,, 2. Front of a rock tacing the wind. Lower middle part of picture shows 
projecting knobs of quartz; middle of picture is a more horizontal 
surtace with corrugations ; upper middle portion is a vertical surface 
facing wind, and studded with knobs of quartz. Scale, 6 inches. 


Pratt XXIX. 


_,,.8. Two specimens of corrugated rock surface. Left-hand specimen was 

a a surtace which met wind obliquely ; right-hand specimen an horizontal 

surface. Scale, 4 centimetres. ; , 

~,, 4. The sill of mica trap which is met obliquely by the wind. Top front 
' - windward corner of each block worn away. Scale, 1 foot. 


306 T. Sheppard—A Buried Valley, Flamborough. 


V.—A Borrep Vartiey at Norra Sea Lanpine, Framporover. 
By T. Suepparp, F.G.S. 


URING the last few weeks East Yorkshire seems to have been 
severely dealt with by wind and hail and flood, and in common 
with the rest of the area the cliffs have suffered. Geologists, however, 
are able to profit where others lose, and as a result of disasters can 
obtain useful information in reference to the structure of a district. 
Perhaps one of the most interesting exposures that has recently been 
made occurs at the south extremity of North Sea Landing, Flam- 
borough, where a large amount of cliff has recently shd down on the 
beach. 

There have been two landslides at this particular point; the upper 
one, which occurs at the top of the cliff at a height of about 125 feet 
above the sea, has carried away the footpath along the cliff edge, and 
in other ways has made things disagreeable. Beyond exposing a clean 
face of purple Boulder-clay, however, it has revealed nothing of 
particular geological interest. 

The second landslide occurs almost immediately below, in the part 
of the cliff which rises to a height. of about 35 feet direct from the 
beach. There is still a tongue of soft Boulder-clay, which forms 
a talus, and covers up part of the section, as shown in the diagram. 
This second landslide has exposed a glacial valley which apparently 
at one time had an outlet to the sea at this pomt. As one faces the 
land, the section occurs immediately to the right of the concrete slope 
up which the fishing cobbles are drawn. 


Section of lower part of cliff at south extremity of North Sea Landing, Flamborough. 
1, Basement Boulder-clay, 15 feet; 2, angular chalk ‘grut’, 6 feet; 3, chalk 
rubble, 6 feet; 4, chalk with flints, 20 feet; 5, talus; 6, beach. 


The upper part consists of about 15 feet of dark lead-coloured 
Boulder-clay, very different in appearance from that on the higher 
slopes. This bed evidently represents the ‘basement’ clay; it 
certainly is precisely similar to the deposit which occurs immediately 
above the chalk ‘wash’ at Sewerby. This Boulder-clay entirely 
covers the solid chalk at North Sea Landing, as well as the deposits 
resting in the pre-Glacial hollow. The Chalk itself, which is to the 


right of the section, is about 20 feet in exposed thickness, and contains 


Dr. A. Wilmore—Uralite and other Amphiboles. 307 


thin beds of flint, and the echinoderm Molaster planus. Where the 
Chalk has been cut into by the valley the upper portion is considerably 
disintegrated and discoloured. This rubble is about 6 feet in thickness 
in the lower part, and thins out towards the right; and where the 
Boulder-clay rests directly upon the Chalk it is missing altogether, 
having probably been planed off by the moving ice. 

To the left of the section there is a wedge-shaped mass of fine, 
clean, angular chalk ‘ grut’, which is about 6 feet thick at the left of 
the section and gradually tapers off towards the right. This ‘ grut’ 
is evidently of very early date, as it contains a fairly large proportion 
of small well-rounded quartzite pebbles, such as occurred at the top of 
the Wolds in pre-Glacial times.’ The chalk ‘grut’ at North Sea 
Landing is precisely similar to the deposit at Sewerby described by 
Mr. G. W. Lamplugh*; in fact, in general appearance it is precisely 
similar to that on the buried cliff, though unfortunately there is no 
beach material exposed at North Sea Landing, nor is this to be 
expected. The section just exposed at North Sea Landing therefore 
seems to indicate the position of a pre-Glacial outlet on Flamborough 
Headland, which has not previously been described. This had been 
partly filled in by chalk ‘ wash’ in early Glacial times; the whole 
valley had subsequently been blocked by drift during the Great Ice 
Age, and had since remained hidden until exposed by the recent 
landslip. : 


V1.—Tuxr DEVELOPMENT OF URALITE AND OTHER SECONDARY AMPHIBOLES : 
A BRIEF History oF RESEARCH IN THAT SUBJECT. 


By AuBert WitmorE, D.Sc. (Lond.), F.G.S. 


N the year 1831 the famous mineralogist and chemist, Gustav Rose, 
I described a mineral which he had observed in his travels in the 
Urals the previous year.* He pointed out that he had found in the 
ereenstones of the Urals crystals with the cleavages and the prism 
angle of hornblende, but with the external form of augite. The 
porphyritic crystals of these greenstones are sometimes hornblende, 
sometimes augite. 

In a greenstone near Bogoslowsk, 437 versts north of Ekaterinberg, 
there are large dark crystals of hornblende with perfect cleavage. 
They have also the crystal form of hornblende, showing typical 
symmetrical six-sided sections with two angles of 1243° when the 
section is transverse to the ortho-axis, and angles of 1563° when the 
section is parallel to that axis. There is often a core of augite, and 
in the larger crystals this core is surrounded by a comparatively 
narrow zone of dark hornblende. In the smaller crystals the augite 
core is very small and sometimes it is quite wanting. To these 
erystals of hornblende, so clearly derived from augite by some 
alteration, he gave the name of Uralite. 


1 See Zhe Naturalist for 1904, pp. 54-6. 
2 Quart. Journ. Geol. Soc., August, 1891, pp. 384-431. 
3 Pog. Ann., 1831, Bd. xxii. 


358 Dr. A. Wilmore—Uratite and other Amphiboles. 


In giving reasons for the grouping of hornblendes and augites into 
one family, he called attention to the fact that when hornblende is 
fused in a platinum or graphite crucible, crystals result which have 
the form of augite. Augite crystals are found in slags, but never 
hornblende crystals. The melting-point of hornblende is lower than 
that of augite. In 1833 Rose gave further localities for uralite.1 

Meanwhile Professor Glocker had cast doubts on the secondary 
origin of this uralite; he had suggested that it might be due to 
hornblende enclosing, in crystallizing, a core of augite, or that an 
original crystal of augite had had a zonary growth of hornblende 
formed round it (Schwegger’s Jahrbuch, Bd. v, p. 873). Rose 

replied to these suggestions, and insisted on the unity of the augite 
- and hornblende families. He also gaye further localities for secondary 
hornblende.* Rose then discussed the question whether hornblende 
and augite should be considered as two dimorphous substances, and he 
showed that though their chemical composition is very similar it is 
not identical. Later on he suggested the possibility of the change 
from augite to hornblende being due to the higher oxidation of the 
ferrous oxide of the augite. 

These observations of G. Rose are the first systematic descriptions 
of a secondary mineral, and are the precursors of much important 
work in connexion with changes in the minerals of rocks which could 
only be carried out after the application of the microscope to petro- 
logical study. 

The subject does not seem to have attracted much attention until 
the era of microscopic petrology had dawned, but from 1876 onwards 
one finds a continuous series of important papers dealing more or less 
directly with uralite. 

In 1876 J. A. Phillips called attention to the ‘‘ pseudomorphic 
origin’? of many of the minerals of the greenstones of Western 
Cornwall.? Some of the rocks are gabbros or dolerites, in which the 
original constituent minerals are occasionally, to a great extent, 
unchanged, but are sometimes almost entirely represented by 
‘* pseudomorphic forms ’’. 

In the same year 8. Allport described the rocks surrounding the 
Lands End mass of granite. Allport made an interesting observation 
which shows that he regarded the process as almost entirely one of 
paramorphism. ‘‘ The alteration that has taken place appears to be 
the result of internal rather than of external action; in other words, 
it must have been caused by a more or less complete decomposition 
and re-arrangement of mineral substances in situ, and not to any 
great extent by the introduction of new material from without.” . 

This seems to have been one of the first suggestions, that the 
production of hornblende by change from augite is one of simple 
paramorphism, an idea which was afterwards developed more fully, 
especially by G. H. Williams. As will be seen later, it does not now 
seem feasible to regard the change as of so simple a nature, at any 


Pogg. Ann., Bd. xxvii, pp. 97-106. 

Tbid., 1834, Bd. xxxi, pp. 609-22. Dana gives the date as 1831. 
Quart. Journ. Geol. Soc., 1876, vol. xxxii, pp. 155-78. 

4 Ibid., pp. 407-27. 


ow re 


Dr. A. Wilmore—Uralite and other Amphiboles. 309 


rate in the majority of cases. Rose’s original suggestion, though 
enly touching one aspect of the possible chemical changes, was 
nearer the truth. ce 

In 1880 yon John described Flysch gabbros from Bosnia (‘‘ Uber 
Kryst. Gest. Bosniens”’?: Jahrb. der k.k., etc., Vienna, 1880), and he 
stated that the kind of secondary hornblende produced depends upon 
the composition of the original pyroxene. Brown hornblende results 
from the alteration of dark diallage, but green hornblende from the 
alteration of green diallage. The secondary brown hornblende is very 
strongly dichroic, but the hornblende derived from the light-green 
diallage is fibrous and almost colourless. The hornblende passes by 
further change into chlorites. 

Cohen (Sammlung von Mikrophot. von Mineralien u. Gest., Stuttgart, 
1884) illustrated the development of uralite in his pl. xlvi, figs. 1-4. 
Fig. 1 shows the beginning of uralitization in the periphery of a crystal, 
and is taken from a micro-section of the so-called uralite-porphyry 
from Predazzo in the Tyrol. Fig. 2 shows the beginning of uralitiza- 
tion in the central part of a crystal, and is from a ‘ proterobase’ 
from near Audlan in the Vosges. Fig. 3 shows complete uralitization ; 
section parallel to the vertical axis, and is again from the uralite- 
porphyry of the Tyrol. Fig. 4 shows complete uralitization ; section 
nearly at right angles to the vertical axis. It is from the so-called 
uralite-porphyry of Miask in the Urals. The form is augite, the 
cleavage that of hornblende. 

An important work is Lehmann’s study of the crystalline schists 
of Saxony, etc.1 In ch. xi, p. 191, which deals with gabbros 
and amphibole rocks (Amphibolgesteine), he mentioned a series of 
secondary minerals, among which are amphibole, saussurite, magnesia- 
mica, ete. He described the change from pyroxene to amphibole as 
one of paramorphism. Later, p. 197, he described amphiboles of 
secondary origin, which are sometimes like smaragdite, sometimes like 
actinolite. The amphiboles and other secondary minerals are due 
in part to pressure. An important observation is that the formation 
of magnetite often accompanies that of amphibole derived from 
hypersthenes rich in iron. 

We now come to the very important series of contributions made by 
Professor Judd during the years 1885-90. Though not the earliest of 
the series it may be well to take first the Presidential Address to the 
Geological Society of London in 1887.2, This address deals with the 
morphology, physiology, chorology, and etiology of minerals. In 
the section treating of the physiology of minerals Professor Judd 
pointed out the importance of recognizing the different structure- 
planes of crystals. The most obvious of these are the cleavage-planes. 
These, however, are not the only latent structure-planes in crystals. 
Brewster, Reusch, and Pfaff had shown long ago that when crystals 
are subjected to pressure in certain directions their molecules appear 
to glide over one another along certain definite planes within the 
crystal, and if we examine optically a crystal which has been treated 

1 Untersuchungen wiber die Entstehung der Althrystallinischen Schiefergesteine, 


Bonn, 1884. 
* Quart. Journ. Geol. Soc., vol. xliii, p. 68 et seq. 


360 Dr. A. Wilmore—Uralite and other Amphiboles. 


in this manner it is actually found to exhibit a series of twin-lamellee 
arranged parallel to the so-called gliding-planes. 

There is still a third and even more subtle set of structure-planes in 
crystals, those, namely, for which the name of solwtcon-planes has been 
proposed. 

In the section dealing with the ‘etiology’ of minerals (the causes 
by which the existing forms, capabilities, and position of minerals and 
rocks have been determined) Professor Judd compared the change from 
unstable monoclinic sulphur—by a pressure of 5000 atmospheres—to 
the stable rhombic form, and that of yellow mercuric iodide, by simply 
rubbing, into the stable red tetragonal form, with the ‘“‘ paramorphic 
change of pyroxene into hornblende, which is so frequently exemplified 
in the earth’s crust’’. 

In the next paper to be noticed he explained his now well-known 
theory of schillerization, and showed the connexion between this 
process and the planes of discontinuity in crystals.! This paper is of 
importance in connexion with uralitization, as it deals to some extent 
with augite, diallage, and the amphiboles, and the changes set up in 
the pyroxenes. 

The difference between minerals found at great depths and the 
same minerals found near the surface is sometimes original—due to 
pressure and slow growth—sometimes secondary, such as the bands 
of fluid enclosures, the avanturine structure, and the chatoyant 
phenomena. 

The same phenomena, but more closely connected with the subject 
of this paper, were further elucidated in a paper by Professor Judd in 
1890.2, In that paper he reviewed the work of Miigge on the 
diopsides of Ala, of Phillips and Teall on the Whin Sill augites, and 
showed that augites in the Tertiary basalts of Ardnamurchan present 
the same features, viz. lamellar twinning parallel to the basal plane 
(001) and not parallel to the orthopinacoid (100). According to the 
work of Miigge this may have been caused by pressure. The lamellar 
twinning or parting of diallage, parallel to the orthopinacoid (100), 
is due to solution acting along the solution-planes. 

There is one other paper by Professor Judd which should be included 
in this important series. This paper deals with a pyroxene-felspar 
rock at Oodegaarden, near Bamle, in Norway. This rock has been 
converted into hornblende-scapolite rock. MM. Fouqué and Michel- 
Lévy had shown that by fusion (with a trace of sodium fluoride) 
and slow cooling this hornblende-scapolite rock is, in turn, converted 
into a pyroxene-felspar rock. 

The change of felspar into scapolite may be followed step by step. 
The solvent which attacked the felspar crystals along their solution- 
planes, and which acted under statical pressure, contained sodium 


1 « On the relation between the Solution-planes of Crystals and those of Secondary 
Twinning, etc.: a contribution to the Theory of Schillerisation ’’; Min. Mag., 1887, 
vol. vii, pp. 81-93. 

2 «On the relation between the Gliding-planes and the Solution-planes of Augite”’: 
Min. Mag., 1890, vol. ix, pp. 192-6. 

3 «On the process by which a Plagioclase Felspar is converted into a Scapolite ”’: 
Min. Mag., 1889, vol. viii, pp. 186-98. 


Dr. A. Wilmore—Uralite and other Amphiboles. 361 


chloride. The felspars of this Oodegaarden rock evidently became 
saturated along their solution-planes with sodium chloride in solution, 
and the effect of the internal stresses in the rock masses was to “‘ bring 
about those chemical reactions by which the felspar-molecules were 
broken up and their materials united with the sodium chloride to form 
scapolite’’. 

The pyroxene has undergone a precisely parallel series of changes. 
The original pyroxene was very nearly colourless, probably an enstatite. 
It was converted into a schillerized ‘ bronzite’ by enclosures parallel 
to a pinacoid. This pale-coloured bronzite is, in places, found to be 
acquiring the characteristic colour, pleochroism, and absorption of 
brown hornblende. 

‘The last stage in the change of the Oodegaarden pyroxene is seen 
in certain crystals which; around their edges and in certain patches 
in the middle, exhibit the full pleochroism, the absorption, and the 
characteristic cleavage of hornblende. This is often accompanied by 
‘oeranulation’ of the broad plates of the original pyroxene. The 
original rock appears to have a perfectly granitic structure, but the 
derived hornblende-scapolite rock has a granulitic structure. 

The effects produced are the results— 

(1) of chemical action resulting from statical pressure (schillerization) ; 
(2) of changes induced by the internal stresses set up in a rock during its 
deformation in the act of flowing (dynamo-metamorphism). 

Professor Judd described the change from pyroxenes to hornblende 
as a ‘paramorphic’ one, but that from felspar to scapolite as a 
‘pseudomorphic’ one. 

Two important papers of a different type by Professor Judd may 
now be noticed. ‘The first of these is his well-known paper on the 
Peridotites of Scotland. In this paper he gave a classification of 
pyroxenes with ‘ Schiller’ varieties, which is here reproduced. 


Unaltered forms. ‘ Schiller’ varieties. More altered forms. 
‘ Enstatite proper Diaclastite ? 

Enstatites Proto-bronzite Bronzite Tale? 

(Rhombic) Proto-hypersthene Hypersthene } j 
Amblystegite Hypersthene Bastite 

Tere Diopsides Diallage and Green diallage 
ugites ase Baath quia 
(Monoclinic) ugite proper seudo- and 

Hedenbergite hypersthene Smaragdite 


An interesting alteration series is given on p. 3881 of this paper— 


Smaragdite 
Actinolite and 


Augite, diallage, green diallage 
similar hornblendes. 


On p. 386 he distinguished ‘weathering’ changes which produce 
kaolinization, uralitization, serpentinization from the changes which 
produce schillerization. The latter is deep-seated, the others are not 
deep-seated. 

The next paper of Professor Judd deals with the Tertiary Gabbros 
in Western Scotland and Ireland.? In it he emphasized most strongly 


1 © Qn the Tertiary and older Peridotites of Scotland’’: Quart. Journ. Geol. Soc., 
1885, vol. xli, pp. 354-418, pls. x—xiii. 
* Quart. Journ. Geol. Soc., vol. xlii, p. 49 et seq. 


362 Dr. A. Wilmore—Uralite and other Amphiboles. 


the unstable nature of the minerals of the basic rocks. The felspars 
are found changed into saussurite, the augites into hornblende, the 
olivine into serpentine and magnetite. Still further changes may 
have taken place by which the rock is converted into hornblende 
schist or gneiss. 

Almost contemporary with this important series of papers were 
several contributions by Dr. Teall. Of these the first was an oft- 
quoted paper on the Metamorphism of a Dolerite Dyke into a Horn- 
blende-schist.1 At Scourie in Sutherlandshire occurs a dyke of 
hornblende-schist, which is clearly the result of metamorphism of 
a dolerite. In this paper Dr. Teall made a number of very important 
observations relative to such questions as the various stages in the 
development of the secondary hornblende and the production of 
foliation. 

Of the two minerals, augite and hornblende, the former appears 
to be the stable form at high temperatures, the latter at low 
temperatures, ‘“‘so that any condition tending to facilitate molecular 
readjustment must necessarily tend to facilitate the change from 
augite to hornblende. The enormous pressures brought into operation 
in the process of mountain-making may not unreasonably be supposed 
to supply such conditions.” 

Analyses of the dolerite of the hornblende-schist are given, but 
apparently the only safe conclusions from percentages which are very 
similar in the two cases are— 


(1) That the change has almost been one of simple paramorphism. 
(2) That there may have been some conversion of ferrous into ferric oxide. 


= if HelO!> =. Anema (eS Hornblende- ( FeO . Pieri ((i 
Dolerite { ire, Oe a so dchish  \(Blas'O) nena 
In a paper dealing with some minerals from the Lizard,? Dr. Teall 
described a (probably) secondary hornblende, a very pale variety 
occurring in a gabbro-schist at Pen Voose. This was analysed by 
Mr. J. H. Player. 


Si Oz ; - 48°8 CaO : , 12:2 
Ale O3 a 10°6 MgO c 18°6 
Fez O03 ile7 Ignition loss 1°8 
FeO 4:7 


On this analysis Dr. Teall remarks: ‘‘If this hornblende be 
secondary, then its composition does not bear out the view that 
secondary hornblende is derived from pyroxene by a paramorphic 
change.”’ 

In 1885 Dr. Hatch? described gabbros passing into amphibolites, 
the alteration series being— 

Normal gabbro, hornblende gabbro, amphibolite, epidote rock. 
Another alteration series is suggested, as follows :— 
Normal gabbro, uralite gabbro, actinolite or nephrite-schist, serpentine. 


1 Quart. Journ. Geol. Soc., 1885, vol. xli, pp. 133-45. 
2 «« Notes on some Minerals from the Lizard ’’: Min. Mag., 1888, vol. viii, 
p. 116-20. 
3 « Uber den Gabbro aus der Wildschnonau in Tyrol,” etc.: T.M.P.M., 1885, 
Bd. vii, pp. 75-87. 


Dr, A. Wilmore—Uralite and other Amphiboles. . 363 


Pressure is clearly seen to have been effective in converting the 
diallage into hornblende. The crystals of the former were bent, 
stretched, and partly destroyed. Hornblende is developed along the 
eracks in patches and round the edges. A large quantity of magnetite 
has been developed as the result of the change from diallage to 
hornblende. The extent to which secondary hornblende has been 
produced is a measure of the schistose character developed in the rock, 
until, with complete change of the original diallage to hornblende, an 
amphibolite or nephrite-schist is produced. 

The next contribution to be noticed is that of Harker in his 
Sedgwick Prize Essay of 1888.1 In ch. vi, on Diabase Sills, ete., it 
is pointed out that the augite has fringing growths of hornblende, 
these also traversing it in strings and sometimes extending into the 
decomposed felspar. This secondary amphibole is always in crystalline 
relation with the augite from which or in which it grows. 

The pseudomorphic hornblende is for the most part truly secondary 
in the ordinary sense of the word. In one or two examples, on the 
other hand, there are appearances which suggest that the amphi- 
bolization may have begun before the final solidification of the rock, 
e.g. when a grain of augite is seen partly pseudomorphosed by 
hornblende which is in crystalline continuity with hornblende 
moulding the grain. 

We now come to some of the more important papers from the pens 
of the American petrographers. First among these may be taken 
a paper by G. H. Williams.” This a very suggestive paper. It 
is pointed out that pyroxene and hornblende are two different 
erystallographic forms of essentially the same molecule. Some 
experimental work is reviewed. In 1824 Mitscherlich and Berthies 
melted tremolite at the Sevres pottery works and found that augite 
resulted on slowly cooling. G. Rose in 1831 had performed a similar 
experiment with actinolite from the Zillerthal. Fouqué and Michel- 
Lévy have since corroborated. A second paper by Williams in 1890 
contains important suggestions upon the whole question of secondary 
amphiboles. This memoir is intended as a contribution to the study 
of dynamic or regional metamorphism. 

Of the various types of alteration discussed, uralitization occupies 
a prominent place. It is made to include the derivation of any 
hornblende, fibrous or compact, from pyroxene. In discussing this 
process it is pointed out that though it has often been referred to as 
one of paramorphism itis more than that in many cases. Forehhammer, 
Rose, and Svedmark have shown that when augite changes to fibrous 
hornblende, magnetite and often calcite are separated out between the 
needles. 

Williams pointed out that Harrington, of Montreal, had analysed 
three stages in the alteration from pyroxene to a secondary fibrous 
hornblende, and found that during the change there was a loss of lime 


1 Bala Volcanic Series of Caernarvonshire, Cambridge University Press, 1888. 
* «On the Paramorphosis of Pyroxene to Hornblende in Rocks’? : Amer. Journ. 
Sci., 1884, vol. xxviii, No. 16, pp. 259-68. 

5 “The Greenstone Schist Areas of the Menominee and Marquette Districts, 


Michigan ” : Bull. U.S.G.S., 1890, No. 62. 


364. Dr. A. Wilmore—Uralite and other Amphiboles. 


and a gain of magnesia. (This change is, however, far from constant. 
See, e.g., Teall on the Scourie Dyke.) 

It was further pointed out that the schistose structure of the rocks 
is largely due to the production of fibrous hornblende. This secondary 
fibrous hornblende does not remain in the area formerly occupied 
by the pyroxene; amphibole needles are even found along the 
cleavage cracks of the felspars. Some other points from this important 
memoir are— 

(1) Brown hornblende passes into green hornblende by the reduction of its 
iron from the ferric to the ferrous state ; afterwards loss of iron produces 
fibrous and less coloured hornblende. 

(2) Very often there is a double hornblende zone round a pyroxene core ; first 
Ces brown and more compact hornblende, then green and more fibrous 
hornblende. 

Another important United States monograph is that of F. D. Chester. 
He distinguished between tremolite and fibrous green hornblende in 
his remarks on rocks at Iron Hill. Tremolite is evidently regarded 
as colourless or nearly so. Fibrous green hornblende surrounds 
hypersthene cores, and tremolite fibres are developed irregularly 
within the core. Much magnetite is set free as the result of the 
change, which Chester described as a paramorphic one. 

It is pointed out that ‘ uralite’ is used in an ambiguous way— 

(1) To indicate a substance with the external form of augite, but the cleavage 
and optical properties of hornblende. 

(2) Fibrous hornblende is loosely described as uralite. 

The three papers by W. 8. Bayley on the Basic Massive Rocks of 
the Lake Superior Region necessarily contain several references to 
uralite and uralitization.* The first of these papers gives an interesting 
history of the classification of the gabbros from the time of Hauy. 
The third article contains an account of the different structure-planes 
noticeable in some of the augites. Diallage cleavages are accentuated 
by dark decomposition products, the most abundant of which are tiny 
irregular black and brown dots. These are scattered everywhere 
throughout the pyroxenes, but are accumulated most thickly in the 
neighbourhood of the cleavage lines. Peculiar platy inclusions 
characteristic of gabbro-diallage are seen in some of the pyroxenes. 
These are often arranged in straight lines crossing the parting-planes. 
They are frequently so crowded that the line of inclusions appears 
as a dark bar crossing the diallage at various inclinations to the 
cleavage. 

In 1888 A. C. Lawson, of the Canadian Survey, made some con- 
tributions to our knowledge of the subject. In a chapter on the 
Petrography of the Keewatin Series he pointed out that the pyroxene 
of rocks of the gabbro type is more resistant to ‘ paramorphie change’ 
than the augite of the diabases. Shreds of fibrous hornblende or 
actinolite derived from augite are observed to have been developed 
within the substance of the fresh plagioclase, and along its line of 
oe “‘ The Gabbros and Associated Rocks in Delaware’’: Bull. U.S.G.S., 1890, 

0. d9. 

* Amer. Journ. Sci., 1893, vol. i, pp. 433, 587, 688. 

3 Report on the Geology of the Rainy Lake Region: Geol. and Nat. Hist. Surv. 
of Canada, Montreal, 1888. 


re 


Dr. A. Wilmore—Uralite and other Amphiboles. 365 


contact with the augite. In another part he noticed that secondary 
hornblende, chlorite, and epidote have been developed very extensively 
along cleavages and cracks of the fresh plagioclase. 

The recent Survey memoir dealing with the north-west of Scotland? 
contains numerous references to the subject. It is shown that 
hornblende is sometimes compact and gives no evidence of secondary 
origin, but on the other hand much of the hornblende is evidently 
secondary after pyroxene. Some of the hornblende-felspar rocks of 
the Lewisian gneiss show hornblende with pyroxene cores (p. 62). 
The basic dykes and sills also show much secondary hornblende. The 
famous Scourie Dyke (wide ante) is quoted as an example. 

The presence of pyroxene cores in hornblende, the occurrence of 
needles of hornblende in the felspars (p. 93), the extension of the 
hornblende individuals parallel to the direction of shearing are 
observations similar to others already noted. Granulation of pyroxene 
is also noticed. 

The larger textbooks of mineralogy and petrology have, of course, 
devoted some space to a consideration of this subject. Zirkel, in his. 
Lehrbuch der Petrographie,* discusses ‘‘ Secundiire Amphibole”’ at some 
length. There is a good general summary of the chief observations 
followed by a discussion of the nature of the chemical changes. 
involved. One observation is worth reproduction. Schwerdt (Zeit. 
Geol. Ges., 1886, p. 225) records a case of Chiness diorite in which 
uralitization has commenced in the middle of the augite crystals so 
that green fibrous hornblende is seen to be surrounded by an envelope 
of compact augite. 

In the chemical discussion it is emphasized that the passage from 
pyroxene to amphibole is more than a mere paramorphism; it is 
a change of augite substance into hornblende substance. The analysis 
of the Ottawa uralite by Harrington is given (ede ante). This shows 
a loss of CaO of 9 per cent. and a gain of Mg O of 33 per cent. There 
is an increase of both ferrous and ferric oxides. There is also an 
analysis of a uralite derived from the pyroxene of a gabbro from 
Zwartekoppies (Dahms). This shows a gain of CaO of 6 per cent., 
a loss of Mg O of 6 per cent., and a gain of Fe O of 3 per cent. These 
results are obviously quite contradictory, but it is pointed out that the 
first case concerns a basic rock rich in lime (24°44 per cent.), while 
the second deals with a rock poor in lime and rich in magnesia and 
iron oxides. 

The deposit of needles and microliths of hornblende in the felspars. 
of many rocks—the so-called erratic (gewanderte) hornblende — 
receives fairly full treatment, and there is a series of references. 

Quite recently MM. L. Dupare & T. H. Hornung*® have made 
a most interesting contribution to the literature of this subject. Their 
paper is entitled ‘‘Sur une novelle théorie de Pcuralitisation”’. They 
describe the alteration noticed in a fine series of rocks collected in the 
Northern Urals. These rocks are very ‘fresh’ and are made up of 


1 « The Geological Structure of the North-West Highlands of Scotland ’’?: Mem. 
Geol. Sury. Great Britain, 1907. 

* 1893, vol. i, p. 316 et seq. 

3 C.R. Acad. Sci. Paris, vol. cxxxix. 


366 Dr. A. Wilmore—Uralite and other Amphiboles. 


basic labradorite, pyroxene, green hornblende, and magnetite. AIL 
the forms and stages of uralitization may be seen, and it is possible to 
separate completely specimens of the almost unaltered pyroxene and 
the almost fully uralitized mineral. The results of the mean of two 
concordant analyses of these extreme cases are given. 


Pyroxene, D. 3358. Amphibole, D. 3°213. 


SiO, TEE Aas oP oe ON ee 43°34 
Al, O5 CRUSOE OBA te. LO eae 
Fee O3 £ : : —- 5 4 P 10°44 
FeO 6 ‘ a 10:07 : i F 7°92 
MnO . : : Traces , : 5 Traces 
CaO : 5 : 23°33 : ‘ 5 13°06 
Me 0 SUSAR ST AMMAR oct! 
K,0 Ogee zee i eRe 0-02 
15 0 BS reat a we cle ae 1:90 

Loss on heating . 5 — 0 . : 0:22 
100°25 102°10 


The authors claim that these analyses dispose of the idea of 
a dimorphous molecule, and that the remarkable freshness of the 
rocks preclude any idea of hydrochemical processes. The examina- 
tion of a great number of sections shows that the manner of the 
uralitization depends upon the permeability of the pyroxene. If 
the latter are impermeable the change is only peripheral; if, however, 
there exists in the pyroxenes ‘‘ une ligne de pénétration ou un 
accident quelconque dans la structure” the uralitization is internal. 
This is interpreted as showing that the pyroxenes after crystallization’ 
have been acted upon by the still liquid magma. The primordial 
magma has first of all allowed the crystallization of pyroxene and 
basic felspars. Before the complete consolidation of the rock the 
bath has been modified in composition by the action of mineralizing 
agents. The bath, thus modified, has reacted upon the pyroxenes, 
enriching them in alumina and in iron and depriving them of 
some lime. 

It appears probable that the explanation of Dupare & Hornung 
applies only to certain cases, otherwise one would expect uralitized 
pyroxenes to be as common in recent rocks as in more ancient igneous 
rocks, whereas it has over and over again been pointed out that 
uralitization is rarely found in the more recent basic rocks. The 
suggestion at once occurs that uralitization is a general term which 
has been used to describe more than one type of mineral alteration. 
These types may be tentatively summarized as follows :— 


(1) The alteration of diallage to uralite by the action of hot liquids under 
pressure and at high temperature and containing various dissolved salts, these 
liquids having penetrated the various planes of discontinuity in the crystals. In 
this way brown or green more or less compact hornblende may be produced 


according to the nature of the original pyroxene and the composition of the. 


penetrating fluid. 

(2) The alteration of compact secondary hornblende to fibrous actinolite or 
tremolite, by the gradual leaching out under conditions of moderately high 
pressure and temperature of more or less of the iron. This process seems to 
take place in the upper part of the zone of katamorphism, while the former 
process seems to be characteristic of the lower part of that zone. 


Dr. A. Wilmore—Uralite and other Amphiboles. 367 


These two processes cannot, of course, be sharply separated. There 
is every possible gradation and combination of the two. The second 
process may have proceeded to some extent, and then the former may 
be superimposed, with the result that, in some cases, there has clearly 
been a passage from pyroxene through fibrous hornblende to compact 
brown or green hornblende. 

(3) There may be magmatic resorption and corrosion of pyroxenes with the 
result that amphiboles of various kinds, usually aluminous hornblendes, are 
formed on the periphery, and along and near the planes of penetration, and in 
the extreme case there may be complete magmatic reconstructicn of the pyroxene 
into hornblende. When this extreme result has been reached it, will be clearly 
impossible to determine the ‘secondary’ character of the hornblende unless 
there is a series of partially resorbed crystals to act asa guide. It is, of course, 
possible to describe such a hornblende as original. 

This will probably take place in the zone of anamorphism, and in 
the upper part of that zone; while the converse change may be 
looked for in the lower part of that zone, and amphiboles of specific ’ 
gravity 3 to 3:3 may be converted into pyroxenes of specific gravity 
3°2 to 35 approximately. 


Note I, on Melting-points of Pyroxenes and Amphibole—The following results 
have been published by the authors named :— 


Cusack. Doelter. Brun. 

Augite GIR fic 1085° 1230° 
1199° 1200° 

Hornblende 1187° 1065° 1060° 

1200° 1155° 1070° 


Cusack: vide Roy. Jr. Acad., vol. iv, pp. 399-413. 

Doelter : Tscherm. Min. Petr. Mitth., vols. xx-xxii ; Physikalisch-Chemische 
Mineralogie, pp. 99-100. 

Brun: Arch. Sci. phys. et nat., Geneva, vol. xii, pp. 352-75. 


Vogt, Day, and others have obtained much higher melting-points for the simple 
pyroxene diopside, up to 1375°. 

Allen, Wright, and Clement (Amer. Journ. Sci., vol. xxii, pp. 385-438) give 
1521° as the melting-point of the high temperature stable form of the Mg Si 03. 
Instead of simply regarding this simple metasilicate as dimorphous they regard it as 
tetramorphous, as follows :— 


Monoclinic pyroxene ; rhombic pyroxene (enstatite) ; 
Monoclinic amphibole ; and rhombic amphibole. 


The pyroxenes are stable at high temperatures, the monoclinic form being the 
most stable ; the amphiboles are low temperature minerals, and probably change into 
stable pyroxenes at high temperatures. Hence we can understand the formation of 
pyroxene from amphibole as recorded by Lacroix in the lavas of Auvergne. (See 
also Harker, Zhe Natural History of Igneous Rocks, Methuen, 1909, pp. 155-8.) 


Note II, the Angle Relations of Augite and Hornblende.—Take the average prism 
angle of augite as 874° and that of hornblende as 1243°. Now take half of each of 
these angles. The following important relation is now evident :— 

tan 624° is approximately 1:90, 

tan 43#° is approximately -95. 
That is, the tangent of half the prism angle of hornblende is twice the tangent of 
half the prism angle of augite. : 


368 Reviews—Water Supply, Hampshire and Oxfordshire. 


REVIBWS.- 


So MU Neate 
I.—GerotocicaL Survey Memorrs on Warer Svurppty. 


1. Toe Warer Suppry or HampsHire (i1NcLUDING THE IsLE OF 
Wicur), with Recorps oF Sinxines anp Bortnes. By Wititam 
Wuiraker, B.A., F.R.S., with contributions by H. R. Murn, 
LL.D., W. Marrnzws, M.Inst.C.E., and J. C. Turusa, M.D. 
8vo; pp. v, 252, with twomaps. Price ds. 


N our volume for 1909 (p. 180) we drew attention to Mr. Whitaker’s 
Water Supply of Kent, and now he has prepared an elaborate 
account of the springs and streams, the wells and borings of 
Hampshire. In both works are embodied the result of labours 
extending over many years, and including experience gained by field 
work during the geological survey of the respective counties. 

The deepest boring in Hampshire, made during the years 1838-51 
at Southampton, was carried to a depth of 1317 feet through Tertiary 
strata without reaching the base of the Chalk. This is not surprising, 
as the estimated thickness of that formation in the Isle of Wight is 
more than 1700 feet. The oldest formation known in the county 
is the Wealden, above which there occur a continuous series from 
the Lower Greensand to the Chalk, and the most complete series of 
Eocene and Oligocene strata known in any county, the Thanet Beds 
only being absent. The chief water-bearing strata are, in order of 
importance, the Chalk, Lower Greensand, Upper Greensand, and 
Bagshot Series. 

An interesting and instructive map of the valleys of the Terl and 
Itchen is contributed by Mr. Matthews, the object being to indicate 
the position of eighty-six wells, and the contour-lines in the surface 
of the underground water in the Chalk. The data on the map show 
(with two exceptions) the water-level in February, 1899. It is noted 
that the surface-contours of the land, although not coinciding with the 
water-contours, have in general a distinct relation to them; never- 
theless, the water-contours ‘‘ will obviously be moving with the 
seasonal and other variations in the water-levels, and those represented 
on the map can only be taken as showing average and approximate 
levels’’. Thus gaugings made between 1884 and 1899 prove that 
seasonal ‘‘ variations range from about 5 feet in wells in the low 
ground, to as much as 68 feet in the case of wells sunk at the higher 
elevations”’. 

Mr. Whitaker remarks that Hampshire is noted for the largest 
spring supply in the kingdom, that of the Portsmouth Water Company, 
which is derived from chalk water; the springs at Havant and 
Bedhampton yielding from 11 to 21 million gallons a day. 

Many intermittent streams or bournes, swallow-holes, and other 
phenomena are described ; and some particulars relating to the rivers 
are given. 

The records of strata passed through in wells and borings, and 
analyses of water (many of which have been contributed by Dr. Thresh) 


Reviews— Water Supply, Hampshire and Oxfordshire. 369 


occupy the main portion of the work. Sundry mineral waters are 
noted, mostly chalybeate, those of Shanklin and Chale being the best 
known. It is stated that Bembridge is supplied from a shallow well 
in the Bembridge Limestone, known as ‘‘Centurion’s or St. Arian’s 
Well’”’. The former name has been regarded by some as a misnomer, 
recorded by the Ordnance Survey instead of St. Urian’s (here given 
as St. Arian’s). A bibliography contains lists of publications of the 
Geological Survey, the Local Government Board, and of other works 
that bear on the water supply of Hampshire, Particulars relating to 
the rainfall, accompanied by a map, are contributed by Dr. Mill. 


2. Toe Water Suppry oF OXxFoRDSHIRE, WITH ReEcorDs oF SINKINGS 
anD Boritnes. By R. H. Tropeman, M.A., F'.G.8S., with con- 
tributions by H. R. Mitt, LL.D. 8vo; pp. iv, 108, with map. 
Price 2s, 3d. 


f{\HIS work has been appropriately prepared by Mr. Tiddeman, who 

studied geology under John Phillips at Oxford, and after many 
years service on the geological survey retired to the neighbourhood of 
his Alma Mater. 

The strata which come to the surface in the county include the 
entire Jurassic series, the Cretaceous from the Shotover Sands and 
Lower Greensand to the Upper Chalk, together with Reading Beds, 
London Clay, Pleistocene, and Recent deposits. The principal water- 
bearing strata are the Inferior and Great Oolite Series, Corallian, 
Lower and Upper Greensand, Chalk, and Valley Gravel. The deepest 
boring, that at Burford Signet, made during the years 1874-7, 
was carried to the base of the New Red Sandstone Series (depth 
1184 feet), and then into Coal-measures (226 feet), the total depth being 
1410 feet.’ The object was apparently to reach Coal-measures, but 
why no further proceedings were taken when those strata were reached 
has not been made known. As a rule the waters obtained in 
Oxfordshire beneath the Oxford Clay and Kellaways Beds have proved 
to be saline, notably at Oxford itself, at Upper Arncot, Bampton, and 
Kidlington. Where not covered by Oxford Clay good supples have, 
as a rule, been obtained from the Great Oolite beneath the Forest 
Marble and Cornbrash, and from the Inferior Oolite, as at Bicester. 
Saline waters have beer encountered also in the Lower Greensand 
beneath the Gault at Shillingford. Mr. W. W. Fisher, who has 
contributed records of many analyses, remarks that in the waters 
below the Oxford Clay the amount of alkaline salts is usually so great 
that the supplies are unfit for domestic or industrial purposes. He 
believes that the alkalies are normal constituents of the strata, and 
that they have become concentrated in situations where little or no 
circulation has been possible. Long-continued pumping ought in 
these circumstances to improve the supplies. 

Dr. Mill contributes a map and explanatory notes on the rainfall. 
There is also a bibliography, drawn up on similar lines to that noticed 
in the Hampshire Memoir. 


DECADE V.—VOL. VII.—NO, VIII, 24 


370 Reviews—Geology in the Field. - 


II.—Gronroey 1x tHe Fierp. The Jubilee Volume of the Geologists’ 
Association (1858-1908).* Edited by H. W. Moncrron and R. 8. 
Herries. Part III. pp. 433-660, with 6 plates. London: 
Edward Stanford, 1910. Price 5s. net. 

N the March Number of the Gerotogrcan Magazine we called 

attention to the issue of the second part of this Jubilee Volume. 

The third part has now been received, and it contains nine articles. 

‘The Weald” is dealt with by Mr. Herries, who first briefly 
discusses the great anticline, the successive stages of elevation, the 
river-systems, and the denudation. The main characters of the 
different formations from the Purbeck Beds to the Upper Greensand 
are then described, and some account is given of Pleistocene and 
Recent deposits. Finally the author sums up the knowledge acquired 
by the various deep borings. 

‘Northamptonshire (including contiguous parts of Rutland and 
Warwickshire)” is the title of the second essay, contributed by 
Mr. Beeby Thompson, who likewise refers to the local deep borings, 
and thus deals briefly with Archean and other formations not exposed 
at the surface. Those which are to be seen in the field include the 
members of the Jurassic Series from the Lower Lias to the Oxford 
Clay, together with sundry Pleistocene and Recent deposits. In the 
higher stages of the Lower Lias the author recognizes in upward 
succession the following Ammonite-zones: Jamesoni, Pettos (described 
by him in 1899), Lbex, Henleyi, and Capricornus. The Upper lias 
is divided into ‘‘ eight subsidiary zones, or sets of beds”, and is 
covered conformably by the representatives of the Inferior Oolite. 
A zealous collector of fossils, Mr. Thompson has added largely to our 
knowledge of the paleontology of the different strata which occur in 
Northamptonshire. 

_ ‘Tiincolnshire”’ is described by Mr. Jukes-Browne, who took a 
considerable share in the geological survey of the county. Strata of 
Triassic age are first described, and a record of the Boultham boring, 
for the water supply of Lincoln, is given on the authority of 
Mr. Henry Preston. A good supply of water is stated to have been 
obtained from the Keuper Sandstones at the depth of 1563 feet. This 
supply, though abundant, proved to be saline; but we are informed 
by Mr. Preston that a really good supply for Lincoln has since been 
obtained from the Bunter near Retford. The author gives particulars 
of the several divisions of the Lias, of the Inferior Oolite Series with 
its basal ironstone worked at Greetwell, of the higher Jurassic strata 
up to the Kimeridge Clay, and of the Cretaceous Series. After 
describing the Glacial Drifts he expresses his dissent from the view 
of Mr. Harmer that the Honington and Lincoln gaps were formed 
during the Glacial epoch by the overflow of a lake caused by the ~ 
advance of an ice-sheet. ; j 

‘Nottinghamshire ”’ is described by Professor J. W. Carr, who 
deals with strata from the Millstone Grit to the Lower Lias, a series 
marked by great unconformity at the base of the Permian. The 
author remarks that ‘‘ Where the junction of the Permian and Trias 
is seen there appears to be a perfectly conformable passage from the 
one to the other, but the Triassic strata rest in succession on all the 


ee a 


Reviews— Geology in the Field. 371 


divisions of the Permian, and to the west of Nottingham the Trias 
overlaps the Permian, and hes directly upon the Coal-measures”’. 
These conditions suggest that some movements were in progress 
during Triassic times leading to local erosion of the Permian. Some 
account is given of the superficial deposits and the bone-caves of 
Cresswell Crags. 

‘<The Lower Carboniferous Rocks of Derbyshire” are the subject 
of an essay by Mr. Arnold Bemrose, who briefly refers to previous 
excursions to the district. ‘he Carboniferous Limestone and its 
zones of fossils, first investigated in detail by Mr. C. B. Wedd, the 
toadstones, the dolomitized limestone, the caverns, and the lead-mines, 
all receive attention. The so-called Yoredale Rocks are described 
under the heading of ‘ Limestone Shales” (‘“ Upper Limestone 
Shales’’ would have been better); the Millstone Grit is described, 
and there is a brief account of the ‘‘ Sands and Fire Clays in the 
Mountain Limestone”, which are stated to be pre-Glacial. Glacial 
Drift, cavern deposits with Phocene and Pleistocene mammala, Tufa, 
and warm springs are also described. 

‘Staffordshire ” is treated by Dr. Wheelton Hind, who first deals 
with the intrusive rocks of Rowley Regis and other places, and with 
the Silurian. The Carboniferous Limestone Series is next described, 
and then the Pendleside Series, which after all is a portion of the 
Limestone Series. Special attention is given to the life-zones in these 
groups, as well as in the Millstone Grit Series and Coal-measures. 
The Triassic, Pleistocene, and Recent deposits are briefly described. 

‘Kast Yorkshire ”’ is the subject of an article by Mr. Herries, who 
has to deal with a long list of formations between the Lower Lias and 
Upper Chalk. With the aid of many illustrative sections and his 
personal knowledge of the strata and their fossils, an excellent 
summary is given of the main features of this attractive area, and 
particularly of the coast-sections between Redcar and Bridlington. 

“The Lake District and Neighbourhood—Lower Paleozoic Times ”’ 
and ‘‘ The Lake District and Neighbourhood—Upper Paleozoic and 
Neozoic Times”’ are the titles of two essays contributed by Dr. J. E. 
Marr. He deals with many formations from the Skiddaw Slates, 
which represent Arenig and possibly Tremadoc and earlier beds, and 
the Borrowdale Series grouped as Llandeilo, to the Lower Lias of the 
area west of Carlisle, and the Glacial and more recent deposits. The 
various igneous rocks are also described. It is not certain that 
Rheetic beds are absent, but their presence has not been proved 
owing to the covering of Glacial drifts. The leading fossils and zonal 
divisions in the Carboniferous and older Paleozoic rocks are duly 
pointed out. The author observes that a ‘“‘ great hiatus occurs above 
the Carboniferous rocks, for the highest Coal-measures, the whole of 
the Permo-Carboniferous rocks, and the lowest Permian strata as 
developed elsewhere, are absent”’. Here a good deal depends on what 
may be included in ‘‘ Permo-Carboniferous’”. The complex physical 
changes, the main faults and flexures that were produced after Lower 
Paleeozoic times, and again after Carboniferous times, and theirinfluence 
on the present physical features, are concisely described. 


(Part IV will be reviewed next month.) 


312 Reviews—Dr, Hatch—Mines of Natal. 


IIJ.—Report on tHE Mines and Miyerat Resources or Natar (OTHER 
THan Coat). By F. H. Harca, Ph.D., M.I.C.E. Published by 
order of the Natal Government. London: Richard Clay and 
Sons, 1910. 

CLEAR statement as to the actual mineral wealth of a country 

and the present stage of its development is seldom afforded us, 

for where so many interests are at stake an unbiassed account is 

generally withheld. When, therefore, we have the opinion of an 

expert of such wide experience as Dr. Hatch we ought to be truly 

erateful. It is not, however, our province to discuss the commercial 

attitude of this report, nor is it for us to say whether it is politic 

to make known the results achieved by individual and pioneer 
undertaking. 

Though not optimistic Dr. Hatch is certainly not wholly pessimistic 
as to the future mining industry of Natal. What the colony has done 
up till 1908 is forcibly shown by the statistical tables on p. 125, in 
which, by the way, the author luxuriates in a ton of 2440 Ib. 

Geologists will be chiefly interested in the author’s succinct outline 
of the general geology of Natal and Zululand, though some will not 
unhesitatingly accept his correlation of the Table Mountain Sandstone 
of Natal with the Waterberg Sandstone of the Transvaal. Useful, 
too, are the notices of the occurrence and distribution of the metalli- 
ferous deposits in the colony. With the exception of iron, nickel, 
and molybdenum the metals appear to be chiefly confined to the 
complex of rocks older than the Table Mountain Sandstone and 
included by Dr. Hatch in the Swaziland System. The Witwaters- 
rand formation is not recognized, and the auriferous conglomerates 
(‘bankets’) are considered to be contemporaneous with the Swaziland 
Beds, and therefore to be older than the Banket formation of the 
Rand. It is disappointing to learn that the iron-ores nowhere appear 
to be of any great thickness, and that limestones suitable for employ- 
ment as a flux are of rather rare occurrence in Natal. 

To further the mining industry of the colony Dr. Hatch considers 
a geological survey, such as was commenced in 1898 and precipitately 
abandoned in 1905, to be an important factor. 


IV.—Gerotoey. By Professor J. W. Gregory, F.R.S. 8vo; pp. 140, 
with 41 text-figures (including a map). London: J. M. Dent 
and Sons, Ltd. No date. Price 1s. net. 


/Y\HE little work before us is one of a series of Scientific Primers, 

which are intended to give a simple and general account of the 
present state of knowledge in various branches of science. At the 
outset we must find fault with the publishers for not inserting a date 
either on title-page or in preface—a very serious omission in a work 
of which the aim is to be ‘ up to date’. 

In an introductory textbook it is always difficult to know how far 
the knowledge of the reader can be taken for granted in dealing with 
the facts and phenomena. In this respect Professor Gregory has 
succeeded as well as possible, considering that he gives special 
attention to the materials of which the earth is made, and he rightly 


- 


| 
: 
| 


Reviews—F. P. Mennell’s Miner’s Guide. 3873 


refers to Sir W. Tilden’s primer of Chemistry for an explanation of 
chemical processes. Commencing with a short account of the early 
history of the earth, he passes on to the study of rocks, dividing them 
into Primary and Secondary, the former including all the Igneous 
rocks and the latter all the Aqueous or Stratified rocks. This is not 
in accordance with the general usage of the terms, and is to be 
deprecated ; but the descriptions of the rocks and of their method of 
formation are clear and instructive. More generally interesting is 
the section on Physical Geology, in which modern agents and the 
arrangement of rocks in the field are dealt with. Here we note that 
the author applies the term erosion to the widening of a valley, and 
corrosion to the cutting of a gorge. The term erosion is by most 
geologists employed for all kinds of denudation. Under Historical 
Geology the author gives a brief account of fossils and of the geological 
systems, and introduces a short notice of Gondwanaland, which is 
illustrated by a map of the world in the Upper Carboniferous era. 

The primer should prove useful to general readers as well as to 
students and science-teachers, and is well calculated to stimulate 
further inquiry. 


V.—Tue Miver’s Guipzr. By F. P. Mennett, F.G.S. London: 
Gerrards, 1909. 4s. net. 
RESENT-DAY civilization imposes a heavy toll on the mineral 
resources of the globe. There is no metal that is not turned to 
some use. There is no quarter of the globe, not excepting the Polar 
regions, to which the discovery of mineral wealth does not instantly 
attract public attention, and there is no nation in the possession of 
more real and prospective mineral wealth than that which hes within 
our own empire. Yet how few are able to distinguish one mineral 
from another, or have any idea as to the rocks in which mineral 
deposits are likely to occur! Elaborate treatises, and textbooks beyond 
count, are on the market ; but most of these are written for the initiated 
and are not serviceable to the untrained, by whom the want of a clearly 
written and practical guide has long been felt. 

In The Miner's Guide Mr. Mennell has, we think, successfully 
supplied this deficiency in our scientific literature. How rocks and 
minerals are formed, how they occur, by what means they can be 
distinguished, and how their value may be ascertained, are made clear 
to all who possess an elementary knowledge of chemistry. Quite 
fittingly, the author illustrates his text with examples taken from his 
wide knowledge of the mineral deposits of South Africa, Rhodesia in 
particular. Other countries are referred to, but all too briefly. Coal 
and oil are summarily dismissed, and we are erroneously informed that 
the ‘‘ well-known coalfields’’ of Ireland are of Silurian age. 

The practical nature of Mr. Mennell’s clever outline is its chief 
attraction, but we think that a book dealing with a subject of such 
general interest possesses an educational value, especially as in this 
instance the information is obtained at first hand, and the writer has 
the ability to present his subject in a clear and concise manner.. 


374 Reviews—Desor’s Index. 


VI.—Invex to Dxsor’s Synopsis pes Ecurnipres Fossites. By F, A. 
Batuer, M.A., D.Sc., F.R.S. Avec une note sur les dates de 
publication du Synopsis par Jules Lambert. Published by the 
Author, Fabo, Marryat Road, Wimbledon, England, May, 1910. 
Price to subscribers, 7s. 

HIS Index, to the preparation of which the Grorocicat Macazine 

drew attention some time ago, has now been published and 
should prove of great use to every worker on Echinoids, whether fossil 
or recent, and to those who, without claiming to be specialists, 
frequently have occasion to look up a name. Reference is made 
particularly easy by the fact that the Index is arranged in two parts, 
the first under the names of species in alphabetical order, the second 
under the names of the genera, the name of each genus being followed 
by a list of the specific names that are in any portion of the book 
associated withit. The value of such an Index will be more apparent 
when it is remembered that the Synopsis was issued in parts and that 
several of the pages were cancelled, additions being made later on. 

Also there were several series of Addenda, and various names occur 

either in the plates, or in the tables, or in foot-notes, to which reference 

is by no means easy; in fact, many of them almost entirely escape 
observation. 

Systematists have long been puzzled by the fact that this original 
Synopsis was issued in separate parts, and that owing to the destruction 
of the original wrappers they were quite unable to determine the 
dates of the various names that, occur in it. This task has now been 
accomplished for them by Mr. Jules Lambert, who, together with the 
late P. de Loriol, spent many years in trying to obtain the necessary 
details. The whole of the results are summarized in a collation of 
a supposed biblographically complete copy. 

Dr. Bather deserves the gratitude of his fellow-workers for under- 
taking this laborious task, and we may express a hope that their 
gratitude will be shown by a speedy sale of the work. 


VII.—Brier Notices. 


1. Haneine Vatieys.—In the Bulletin of the American Geographical 
Society (1909) Professor D. W. Johnson deals with two questions 
involved in the problem of glacial erosion: (1) Are hanging tributary 
valleys a reliable indication of glacial erosion of the main valley? 
(2) May not hanging tributary valleys result from glacial widening 
of the main valley, instead of from glacial deepening? In the paper 
the author discusses the origin of hanging valleys, and deals with 
a number of glaciated valleys in Europe. 

2. Tur Rexation of Grotocy to TopocrapHy.—Professors D. W. 
Johnson & F. E. Matthes contribute a chapter with this heading to 
Breed & Hosmer’s Principles and Practice of Surveying (New York). 
After pointing out the value of a knowledge of geology to the 
topographer, as giving him ‘“‘some understanding of the conditions 
under which the surface was formed”, the writers point out by a 
series of diagrams the differences between accurately and inaccurately 
mapped mountain areas. They show also how correct contouring of 


eS a 


Brief Notices. O70 


a district brings out the detail of glaciation, alluvial fans, volcanic 
features, dome mountains, and general physiography or topographical 
geology. 

3. Om SuHares or Canapa anp Scorranp.—Dr. R. W. Ells has just 
issued in the Department of Mines, Canada (Ottawa, 1910), a long 
report on the oil-shale industry of Scotland, New Brunswick, and 
Nova Scotia. This report treats of the geology, history, statistics, 
analyses, cost of plant, commercial value, and many other points 
ees to those interested. 

4, ‘ Krepwants’ ok BuFFaLoEs’ WaLLows”’ THE WorK or EarrH- 
worms.—The South African Journal of Science is the organ of the 
South African Association for the Advancement of Science, and is 
a monthly record of science and economics. In the part for Febr uary, 
1910, J. A. H. Armstrong writes on the geology and mineralogy of 
Natal, and he refers incidentally to those curious pits or hollows 
known as ‘‘elephants’ or buffaloes’ wallows’’. Setting aside the 
older theories as to their origin, (1) wallow holes, (2) native iron- 
ore digging, (3) ancient gold-diggings, (4) percolating waters, 
Mr. Armstrong thinks they are the work of earth-worms alone. 
He gives a number of strong arguments in favour of his views, and 
seems to have made a singular and thoughtful observation. 

5. Movunr Erya.—On March 23 this volcano burst forth into activity 
after a series of minor earthquakes, the outbreak being the most 
violent since the great eruption of 1892. Streams of lava issued from 
five craters, and united to form a great stream that moved at the rate 
of more than 60 feet an hour, and was estimated to be 12 feet high 
and more than 1500 feet in width. Quantities of scorize were also 
ejected mainly from the highest crater. The lava-stream subsequently 
divided, portions extending to the Galvagna district, south of Mont 
San Leo, approaching Borello and also Nicolosi. Ultimately more 
than fourteen craters were in eruption. On the evening of March 26 
the volcanic activity ceased, but a renewed eruption, of less intensity, 
was reported on March 28, and on April 9 it was announced that Etna 
ee again in violent eruption. 

THe New Zeatanp Georoeicat Survey in Bulletin No. 7 (New 
Series), 1909, has issued a report on ‘‘ The Geology of the Queenstown 
Subdivision, “Western Otago Division”, by Mr. James Park. This 
is evidently an attractive “district, as Queenstown “is picturesquely 
situated on the raised lake-beaches and great moraine overlooking 
Queenstown Bay and Frankton Arm. Its scenic marvels and sunny 
salubrious climate have made it the chief centre of the tourist traffic 
in the South Island”. The geological formations consist mostly of 
mica-schists grouped as Paleozoic, with strata grouped as Lower 
Miocene (Oamaru Series), Pleistocene, Boulder-clays, moraines, and 
terrace-gravels, and Recent alluvial deposits. Evidence is given of 
overthrusting in the older schists, whereby wedges of Miocene 
strata have been included along certain thrust-planes, a feature of 
remarkable interest. Proof is also presented to show ‘‘ that the Lake 
Wakatipu region was covered by a continuous ice-sheet of vast depth 
in the Pleistocene period—a continental ice-sheet that reached to the 
sea, and probably covered the greater part of the South Island”’. 


Pr) 


376 Brief Notices. 


Gold-bearing lodes occur in the schists, but alluvial mining has been 
by far the most productive source of the metal. Igneous rocks do 
not occur in situ, but many pebbles and boulders occur in the fluvio- 
glacial drifts, and these are described. The work is fully illustrated 
by maps, sections, and pictorial views. 

7. Boarp or AcricuLturE.—We are glad to note that Dr. J. J. H. 
Teall, F.R.S., Director of the Geological Survey and Museum, is 
a member of the Committee recently appointed by Earl Carrington to 
advise the Board on all scientific questions bearing directly on the 
improvement of agriculture. A carefully surveyed geological map on 
the scale of 6 inches to a mile is the best foundation for the more 
detailed study of soils, and indeed for appraising the value of an 
estate. As we noted in reference to Soil Surveys in the United States 
(Guot. Mac., 1908, p. 277), the so-called ‘ soil-maps’ are geological 
maps representing the subsoils or geological formations (whether Solid 
or Drift), there is no attempt to map the constantly varying soils, but 
information relating to their depth and character is given in many 
places on the maps from data obtained by means of spade or 
hand-borer. 

8. ‘‘Sxurcnks oF Gaspé” is the title of a little book by Mr. John 
M. Clarke (Albany, 1908), in which the author gives an interesting 
account of the scenery, geology, and of many other matters relating 
to ‘‘that vast peninsula of Hastern Quebec which lies between the 
mouth of the St. Lawrence River and the Bay of Chaleur, facing the 
waters of the Gulf of St. Lawrence”. 

9. GronoeicaL anp PrrrocRapHicaL ResearcHEes 1n THE Norra 
Urats.—‘‘ Recherches géologiques et petrographiques sur |’Oural du 
Nord, le bassin de la haute Wichéra,” by Professor Louis Dupare, 
aided by Professor F. Pearce and Miss Marguerite Tikanowitch (Mém. 
Soc. Phys. et Hist. Nat. de Genéve, xxxvi, 1909, pp. 33-210). In 
this work the authors describe the eruptive rocks (diabases) which are 
generally intrusive in the metamorphic or pre- Devonian rocks, and these 
‘crystalline schists’ are also described in detail. Middle and Lower 
Devonian, Carboniferous, and Quaternary deposits complete the lst 
of formations represented. Brief descriptions only are given of them, 
attention being devoted to the geological structure and physical 
features, and to the mode of occurrence and origin of the iron-ores. 
The memoir is fully illustrated by pictorial views, plans, geological 
sections, and microscopic rock-sections. 

10. Tue Warers or ro Great Lakes or Norru America are described 
by Mr. kK. B. Dole (Journ. New England Water Works Assoc., xxiii, 
1909). Samples were collected monthly for a year from each 
lake, and a tabular statement is now given of the mineral analyses. 
Around Lake Superior igneous and crystalline rocks predominate, 
and the water contains on the average sixty parts per million of solids ; 
whereas Lakes Erie and Ontario contain about two and a half times 
the amount of solid constituents, due mainly to material derived from 
calcareous sedimentary formations. The lakes are almost invariably 
softer than their affluents, as might be expected from the effects of 
direct rainfall. The suspended matter is practically all deposited by 
sedimentation. 


Brief Notices. Ov7 


11. Sawp-Baryres From Karnes, Eaypr (Proc. U.S. Nat. Museum, 
Xxxvill, 1910).—Mr. Joseph K. Pogue describes and illustrates sundry 
forms of Sand-Barytes. The figures recall to mind examples of selenite 
charged with sand-grains, the occurrence of which in the Oldhaven 
Beds has been noted by Mr. Whitaker. As the author remarks, calcite, 
gypsum, and barite are distinguished above all other minerals by the 
large quantities of sand which they can enclose upon crystallization. 
The specimens he describes were probably formed by the deposition 
from solution of barium sulphate in the interstices of loose sand during 
the consolidation of the Nubian Sandstone. 


12. Sxcrions From Deprrrorp snp Carrorp to PLoumsreap.— 
Mr. R. H. Chandler has contributed very useful detailed accounts 
of sections exposed by the two new sewers: Deptford to Plumstead 
and Catford to Plumstead (Trans. West Kent Nat. Hist. Soc. for 
1908-9, 1910). The particulars are systematically recorded and 
illustrated by map and sections. Strata from the Chalk to London 
Clay with superficial deposits were encountered; and in the low-level 
sewer from Deptford, during construction, more than 3,000,000 
gallons of water were pumped from the Chalk in the course. of 
twenty-four hours. Remains of Mammoth and Los primigenius were 
obtained from the Valley Drift at Greenwich. 


13. Fossins In THE ALGonxrAn or Scanpinavia.—In the Stockholm 
“¢Geologiska Forhandlingar”, vol. xxxi, 1909, p. 725, Dr. A. E. 
Tornebohm announces the discovery of fossils in a crystalline lime- 
stone at the northern end of the Great Arfven Lake, west of Lake 
Wener, Sweden, as well as in the Berikalk of Gudbrandsdal, Norway. 
The appearances in question have been known for some time, but have 
only recently been determined by Professor Rothpletz as calcareous 
alge. Beside these Dr. Tornebohm has found other structures which 


appear to be of organic origin. The whole microscopic look of the 


rocks is that of certain younger limestones known to be composed of 
fragments of organisms. 
14. WVicrortan Fosstns —Mr. Frederick Chapman continues his 


energetic attempt to describe the new or little known Victorian fossils 
in the National Museum, Melbourne, in the ‘‘ Proceedings of the Royal 
“Society of Victoria’. His tenth contribution contains worms and 


Crustacea, and includes Silurian Zrachyderma of two species, two 


interesting forms of Zurrzlepas from the same formation, a Ceratiocaris, 


and a Xiphidiocaris. Myr. Chapman invariably draws hjs own figures, 
and if his efforts in that direction are a little crude, we may rest 
assured that his detail is extremely accurate. 

15. Creraczous Prawrs.—Messrs. Stopes & Kershaw describe in the 
Annals of Botany, April, 1910, some pine leaves from the Cretaceous 
of Japan, and discuss their relationship with other Cretaceous species, 
and with the living forms of America. Incidentally the authors 
diagnose the genus Prepinus, Jeffrey, 1908, as that author apparently 
forgot to do so. In a second paper Dr. Stopes describes the internal 
anatomy of a leaf of Nilssonea orientalis, Heer, also from Japan. 
The result of the examination of this specimen seems to show it to be 
primitively Cycadean in character. 


378 Reports and Proceedings—Geological Society of London. 


REPORTS AND PROCHEDIN GS. 


I.—Gerotogicat Socrrery or Lonpon. 


June 15, 1910.—Professor W. W. Watts, Sc.D., M.Sc., F.R.S., 
President, in the Chair. 

The following communications were read :— 

1. ‘The Natural Classification of Igneous Rocks.” By Dr. Whitman 
Cross, F.G.S. 

The author reviews the various sytems of classification which have 
been proposed. He discusses the origin of the difference of composition 
of igneous rocks due to: (1) primeval difference, (2) magmatic 
differentiation, (3) assimilation; and points out that differentiation 
and assimilation are in a measure antithetical processes. 

If the deep-seated magmas of large volume have acquired their 
various chemical characters in different ways, it appears at once 
evident that this primary genetic factor cannot be used in classi- 
fication, unless the characters of different origin can be distinguished 
in the rocks. 

Classification by geographical distribution of chemically different 
rocks is considered, and the groupings proposed by various writers 
are discussed ; and it is shown that the rocks of the Pacific zone of 
North America indicate that they possess provincial peculiarities of 
interest, but that these are not by any means identical with the 
features emphasized by Becke and others as characterizing the Pacific 
kindred. 

The factors of magmatic differentiation are then reviewed. The 
aschistic and diaschistic magmas of Brogger and the ‘ dyke rocks’ of 
Rosenbusch are discussed; and it is contended that certain dyke 
rocks of Colorado show a notable exception to the rule postulated by 
Rosenbusch. The conclusion is reached that the sharp distinction 
between the two ‘dyke rock’ groups is a purely arbitrary one, resting 
on an unproved hypothesis. 

A discussion on the classification by eutectics follows, and the 
writings of G. F. Becker and J. H. L. Vogt on this subject are 
criticized. The view that graphic, spherulitic, and felsitic textures 
are characteristically eutectic is considered to be incorrect, and it is 
contended that magmatic classification by eutectics is fundamentally 
weak, because it rests on hypothesis, because it does not apply to all 
rocks, and because it does not allow for the entire magma of most 
rocks. A classification by eutectics may, in the future, be realized ; 
but it seems inevitable that it must be a classification for a special 
interest, not for the general science of petrography. 

The author considers that the distinction between felspathic and 
non-felspathic rocks which has been so prominent in current systems 
is not only unnatural, but is in the highest degree arbitrary. 

The use of texture is then discussed, and it is shown that classification 
by occurrence, as determining texture, or by texture, as expressing 
the broad phases of occurrence, is based on long disproved generalizations 
made from limited observation. The ‘‘ American Quantitative System 
of Classification” is then briefly dealt with, and the following general 
conclusions are formulated :— 


ee ee 


—— 


a 


i 
A 


Reports and Proceedings—Geological Society of London. 379 


‘« The scientific logical classification of igneous rocks must apparently be based on 
the quantitative development of fundamental characters, and the divisions of the 
scheme must have sharp artificial boundaries, since none exist in Nature. 

‘* Chemical composition is the fundamental character of igneous rocks, but it may 
be advantageously expressed for classificatory purposes in terms of simple compounds, 
which represent either rock-making minerals or molecules entering into isomorphous 
mixtures in known minerals. It is probable that the magmatic solution consists 
of such molecules, and that the norm of the ‘ Quantitative System’ is a fairly 
representative set of these compounds. 

‘¢ The actual mineral and textural characters of igneous rocks are variable qualifiers 
of each chemical unit, and should be applied as such to terms indicating magmatic 
character.”’ 


2. ‘*The Denudation of the Western End of the Weald.” By 
lenny bury, MA. F.1L.S., F.G.S. 

There are two main theories of Wealden denudation—(1) attributing 
the removal of most of the Chalk to marine planation ; and (2) denying 
planation and relying solely on subaérial denudation. Professor W. M. 
Dayis’s suggestion of a subaérial peneplain forms a sort of connecting 
link between the two. 

The evidence in favour of planation which Ramsay and Topley 
brought forward is inconclusive, and might plausibly, if it stood alone, 
be attributed to pre-Eocene causes. On the other hand, Prestwich’s 
arguments against planation are equally weak, while the Chalk plateau 
to which he draws attention strongly supports Ramsay’s views. The 
distribution of chert is fatal to Professor Davis’s hypothesis, and very 
difficult to account for, except on the marine theory. 

In the case of the River Blackwater it can be proved that, long 
after the Hythe Beds of Hindhead were uncovered, the river-system 
remained extremely immature, and this affords very strong grounds 
for the acceptance of the marine hypothesis: 

The evidence of the other western rivers is less conclusive, though 
the Wey and the Mole both provide minor arguments pointing in the 
same direction. ‘The anomalous position of the Arun, at the foot of 
the northern escarpment of the Lower Greensand on either side of the 
Wey, is almost certainly due to comparatively recent captures from 
the latter river, and affords no ground for assuming a river-system of 
great age matured on a Miocene peninsula. 

There is no proof that any of the existing connexions between rivers 
and longitudinal folds are of a primitive character, and, on the other 
hand, there are many alleged examples of transverse disturbances 


having served as guides to consequent rivers. This again, on the 


whole, supports the marine hypothesis, especially if, as there are 
reasons for believing, the longitudinal folds are older than the 
transverse. 


3. ‘An Earthquake Model.” By John William Evans, D.Sc., 
TiLB., F.G:S. | 
This model is designed to show the successive conditions that result 
in an earthquake shock— 
(1) Slow relative movement between two extensive portions of the earth’s 
crust lasting over a long period, and causing 
(2) a state of strain im the intervening tract, leading to 
(3) fracture which relieves the strain and allows 
(4) the adjoining portions of the rock on either side to fly back by virtue of 


380 Reports and Proceedings—Mineralogical Society. 


their elasticity, so as to resume as far as possible their original relation to the 
rock-masses with which they are still connected. This movement of release may 
give rise to two kinds of periodic disturbance : 

(5) short-period vibrations, due to a sudden arrest by an obstacle and 
constituting the earthquake properly so called, and 

(6) a slower backward and forward swing of the rock about the position of 
equilibrium. 

The more important permanent variations in the configuration of 
the earth’s crust in the neighbourhood of the San Andreas fault in the 
Californian earthquake of 1906 are well shown by the model. This 
earthquake is regarded as an incident in the slow northward creep of 
the North Pacific relatively to the adjoining continents, part of the 
process of adjustment of the earth’s crust to the interior—rendered 
necessary by the expansion of the crystalline rocks of the former on 
hydration, and the contraction of the latter as the result of cooling 
and loss of material by volcanic and kindred phenomena. 


The President read the following communication received from 

Mr. S. 8. Bucxman, F.G.S. :— 
May 29, 1910. 

‘Tn my paper on certain Jurassic Species of Ammonites (Quart. Journ. Geol. Soc., 
1910, vol. lxvi, p. 90). 1 proposed for a new genus the name Burtonia (p.97). With 
that kind helpfulness which is so distinctive of American scientific workers, Dr. W. H. 
Dall writes to say that this name is already in use—by Bonaparte for a bird and by 
Bouvignat for a naiad. I therefore desire to substitute the name Bredyia for 
Burtonia in my paper; Bredyia is from the River Bredy (pronounced ‘ Breedy’, 
‘ Briddy’), which flows through Burton Bradstock, and its name presumably furnishes 
the syllable ‘ Brad’. I wish to record my thanks to Dr. Dall for his kindness. 

‘« The opportunity may be taken to rectify a misprint: in p. 68, 1. 7 from the top, 
for ‘ striking ’ read ‘ sticking’.”’ 


II.—MrveratoaicaL Soctery. 
June 7, 1910.—Professor W. J. Lewis, F.R.S., President, in the Chair. 


_ Arthur Russell: On the occurrence of Phenakite in Cornwall. 
Phenakite was unknown in the British Isles until the discovery by 
the author in 1905 of a single specimen at the Cheesewring Quarry, 
Linkinhorne, Cornwall. In 1906 he collected further specimens, 
showing numerous small but well-formed crystals, from a tin lode 
at South Phoenix Mine, Linkinhorne. In an old Cornish collection 
acquired by him in 1909 he found a specimen with as many as forty 
fine crystals; it was labelled “Topaz on Quartz from St. Agnes”’. 
Phenakite was also recognized on a specimen found about the year 
1870 by Mr, J. H. Collins at South Crofty Mine, Illogan, Cornwall. 
Search at the Natural History Museum and the Museum of Practical 
Geology brought to light other specimens of phenakite placed under 
apatite.—Dr. G. F. H. Smith: (1) Phacolite from near Belfast. Two 
types were described. In the first the crystals were large (about 
10-14 mm. across) and much striated, and in the second they were 
small (about 1-2 mm. across) but with plane faces; in both instances 
the crystals were twinned about the trigonal axis, the individuals 
interpenetrating one another, and the forms present were r (1011), 
t (8142), e (0112), s (0221). The measurements accord closely with 
the data given for chabazite. (2) The Crystalline Form of Nitrogen 


Correspondence—D. MW. S. Watson. 381 


Sulphide. Crystals of this rare substance have recently been prepared 
by Mr. F. P. Burt, University College, London, by sublimation. The 
constants obtained were a:5:¢=0'8879 : 10-8480 : B=90° 23’, and 
the observed forms were (100), (010), (001), (110), (101), (011), 
(101), (210), (111), (121), the last four being new. The crystals 
were invariably oniees ae by polysynthetic twinning about 
(101). <A biaxial interference figure with strong positive double 
refraction was visible through (101). —Dr. G. T. Prior and Dr. G. F. H. 
Smith: On a new Arsenate-and Phosphate of Lime and Strontia from 
the Indian Manganese Deposits. Chemical analysis showed that the 
mineral approximates to the arsenic analogue of apatite. The crystals 
were not well formed, but the physical characters as far as they could 
be determined accord with those of apatite. The name fermorite, 
after Dr. L. L. Fermor, of the Geological Survey of India, who has 
made an exhaustive study of the manganese deposits, is proposed for 
this analogue. The presence of strontium, which has not yet been 
detected in apatite, is of interest.—L. J. Spencer: A (fifth) List of 
New Mineral Names. 


CORRESPONDENCE. 


A CHELONIAN FROM THE PURBECK OF SWANAGE, DORSET. 


Sir,—In my article on the above subject (see Guon. Mae. for July, 
pp. 311-14) the following note was sent in too late for insertion :— 
Hooley’s Plestochelys vectensis from the Wealden of the Isle of 
Wight (Guor. Mae., 1900, p. 263) shows a preeneural and seven 
neurals, instead of eight neurals as suggested in the original 
description. The specimen probably indicates a new genus. 
Seeley’s Pleurosternum typocardium, which was _ insufficiently 
characterized in his Index to Aves, etc., in the Cambridge Museum, 
is founded on a specimen of Glyptops ruetimeyert. It is much 
more oval in outline than my Fig. 1, a difference possibly partly 
due to sex, but otherwise shows no new features. The protuberances 
caused by the crushing through of the axillary and inguinal buttresses 
are quite evident. Seeley’s other species, Pleurosternum sedgwichit, 
vansittardi, and owent, appear to be typical examples of P. budlocki. 
D. M. 8. Watson. 


Victornta UNIvERsITY, MANCHESTER. 


THE TERM ‘LATERITE’. 

Srr,—I refuse to plead guilty to the charge advanced by Mr. Scrivenor- 
in your July issue of attempting to force a new definition of laterite 
on geologists and engineers. I only ask that the word shall be 
employed for rocks which are chemically and physically allied to 
that on which it was bestowed by Buchanan. 

‘In dealing with questions of priority of nomenclature we must 
inquire what was the thing (rock, mineral, or organism, as the case 
may be) to which the name was first applied, not why it was so 
applhed. Buchanan found a rock widely extended in India which was 
unlike anything with which he was familiar, and he thought that it 


382 Correspondence—J. W. Evans. 


required a name. As bricks were made of it (not because it resembled 
a brick) he called it laterite, certainly without intending to include 
under it all materials of which bricks could be made. I admit that 
he did not know its true chemical composition, but in spite of that it 
must be accepted as the type of what we ought to call laterite. 

As a matter of fact the majority of geologists and of scientific 
mining engineers are now using the word in this sense, the sense 
which I and others are defending, and that this is so a recent 
discussion in the pages of the Transactions of the Institution of 
Mining and Metallurgy, in connexion with a paper by Mr. G. 
Morrow Campbell on the ‘‘ Origin of Laterite ’’, is sufficient evidence. 
As to the word ‘bauxite’ I have no objection to its being applied to 
a laterite exceptionally poor in silica and iron, and therefore suitable 
for use as a source of aluminium and its compounds, as long as it is 
understood that it is so employed as a commercial mineral term and 
not asarock name. Scientifically, however, it should be restri¢ted to 
a mineral, if such exist, in which two molecules of water are combined 
with one of alumina. 

We shall all look with interest for the results of Mr. Scrivenor’s 
investigation of the chemical nature of the products of tropical 
denudation—under whatever name or names he may describe them. 


Joun W. Evans. 
IMPERIAL INSTITUTE. 
July 1, 1910. 


LATERITE AND BAUXITE. 

Srr,—I am glad to learn from Mr, Crook’s letter in the May 
number of the Grotocicat Macaztne that I am not alone in holding 
certain views regarding the term laterite and also the term bauxite, 
but it is a pity that either side should be led into criticisms that are 
stronger than the occasion warrants. 

I can understand Mr. Crook’s surprise that anyone should decline 
to accept, without question, the new definition of laterite, seeing by 
what authority it is supported, and I grant that the proposed definition 
is attractive. But what, in my opinion, has been lost sight of, is 
that laterite was defined more than a hundred years ago, and that the 
extension of the term in tropical countries has been based on the early 
descriptions, the keynotes of which are brick andiron. When an 
innovation is proposed—for I must with all deference ask still to be 
allowed to consider this ‘aluminous’ definition an imnovation—the 
first question is whether it is practicable, the next whether it is 
necessary. I do not think the change practicable, because the ideas 
of brick and iron have taken firm root and have led to the term being 


widely used for ferruginous rocks, useful in public works and in ~ 


building. As its practicability is denied there is no question of its 
necessity ; but were the change practicable, would the new be better — 
than the old definition? The brick and iron characteristics are easily 
recognized; the aluminous is not. The word ‘laterite’ has no etymo- 
logical connexion with aluminium ; it has with brick, and so, indirectly, 
with iron, since the setting of laterite is dependent, mainly at any 
rate, on the presence of ferric hydroxide. Both Dr. Evans and 


Correspondence—J. B. Scrivenor. 383 


Mr. Crook appear to think—I hope that I am not doing them an 
injustice—that because the two definitions apply to the same thing, 
therefore they are the same. ‘This is hardly logical. They emphasize 
distinct characteristics, scientific and commercial, and are therefore 
different. 

An example illustrating the difficulty, however, will be more to 
the point than a long argument. In the Federated Malay States 
the chief crystalline rock is granite, and the mode of weathering is 
excellently shown by many miles of road sections in hilly country, 
where the transition from fresh rock to soil can frequently be followed. 
The rock weathers in situ to a soft mass, red or yellow, sometimes 
white, in colour, in which one sees round boulders of fresh granite 
that has resisted decomposition and so formed ‘ core-boulders’. 
I have taken a specimen from about midway between the soil and 
the fresh rock, and after drying have treated it with sulphuric 
acid for about one hour over a water-bath. The iron and aluminium 
that went into solution were precipitated as hydroxides, and the 
aluminium hydroxide separated by K HO and re - precipitated by 
ammonium chloride. After ignition I obtained over 13 per cent. 
of alumina, and as I must assume that this alumina exists in the rock 
as a hydrate or hydrates, the rock falls under the proposed new 
definition of laterite. It is a weathering product of a crystalline 
rock containing aluminium hydroxides in a tropical country. But 
no one here calls it laterite or wishes to do so; it does not harden on 
exposure, and is therefore of no use as a substitute for brick. It is 
decomposed granite, and it would be an unnecessary complication to 
eall it anything else, in spite of the interesting fact that a considerable 
percentage of aluminium hydroxide has been formed during the process 
of decomposition. Indeed, it may prove that this feature of tropical 
weathering is so general that it cannot be regarded as characteristic of 
any one decomposition product, and that, if the presence of aluminium 
hydroxides is to be the test of laterite, then there will be a difficulty 
in excluding rocks that have no resemblance to Buchanan’s laterite, as, 
for instance, the china-clay and clay-slate mentioned in my last letter. 

We know that the composition of laterites varies with the character 
of the rock from which it is derived; and I have ventured to propose 
that, for the sake of simplicity, we should call bauxite certain laterites 
in India that have been stated to be bauxite. ‘‘ Laterite is bauxite 
in various degrees of purity.” ‘‘ These are bauxites in blocks and in 
powder.”’ Iam now told that I am guilty of endeavouring to degrade the 
term ‘bauxite’ completely, and that my suggestion is positively harmful; 
while I am furthermore invited to assert that a mineral of a definite 
chemical composition, which has not yet been proved to exist, does not 
exist, and to state what name I propose to give it if it should be 
proved to exist. The word ‘bauxite’, Mr. Crook says, must be reserved 
for a hypothetical mineral of the composition Al, 0, .2H,O, and it 
may not be used as a rock-name until that hypothetical mineral is 
proved to be amyth; but there is some plausibility in my suggestion 
because the term has been used carelessly. 

Bauxite was discovered in France, and France possesses a 
mineralogist who cannot be accused of using mineralogical terms 


O84 Obituary—W. P. Blake. 


carelessly. In his Mlinéralogie de la France et de ses Colonies, ii, 
p. 842, Mons. A. Lacroix says: ‘‘ Aussi me semble-t-il difficile de 
considérer la bauxite comme un minéral defini; il est bien plus probable 
que les produits désignés sous ce nom sont constitués suivant les cas 
par divers hydroxides d’alumine colloides mélangés a des hydroxides 
correspondants de fer et a diverses impurités, argile, sable quartzeux, 
etc. C'est en réalité une véritable roche.” The last sentence of the 
above quotation makes further defence unnecessary. 

This question of the use of the term ‘laterite’ is one in which there 
is abundant room for quiet discussion. My view may be extreme on 
the one side—indeed, is, I suppose, without question extreme in that 
I would like to see the term left to engineers to treat as they wish. 
Nevertheless, the adoption by the majority of geologists of the 
proposed ‘aluminous’ definition would not lead “to a crisis, and 
{ cannot believe that anyone or anything would suffer harm thereby. 
This seems to me to be an admirable opportunity for dropping the 
term altogether, and for substituting in its stead the term ‘bauxite’ 
when the composition justifies it; when this is not the case I would 
advocate the simple term ‘decomposed gneiss’, or whatever the rock 
may be, it being taken for granted that the production of aluminium 
hydroxides in quantity is a feature of tropical weathering. 

J. B. Scrrvenor. 
Batu Gasau, 


FEDERATED MaAtay S7tarzs. 
June 15, 1910. 


OBA 


WILLIAM PHIPPS BLAKE, D.Sc., F.G.S. 
Born June 1, 1826, Diep — 1910. 


W. P. Brake was born in New York, and educated at Yale Scientific 
School. In 1853 he was appointed geologist and mineralogist on the 
U.S. Pacific Railroad Expedition, later on he was geologist to the 
California State Board of Agriculture, in 1864 he became professor of 
mineralogy and geology in the College of California, and at the time 
of his death he was emeritus professor of metallurgy, geology, and 
mining, and director of the School of Mines in the University of 
Avizona. His more important papers relate to the geology and 
mineralogy of California and Arizona; but he had made observations 
on the glaciers of Alaska, on the geology of the Island of Yesso, 
Japan, and was the author of a volume on Zhe Production of the 
Precious Metals, 1869 (see Grot. Mac. for 1868, p. 284, 1869, 
p- 861, and 1874, p. 464). He was elected a Fellow of the Geological 
Society of London in 1876, 


MISCHILOUAN HOU S.- 


Mr. H. B. Mavre, B.A., F.G.8., of the Geological Survey of , 
Great Britain, has been appointed Director of the Geological Survey 
of Southern Rhodesia lately instituted by the Chartered Company. 


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ORIGINAL ARTICLIEHS. 


I.—Txe Orticin or tHE Nite VaLiey In Ecyrt. 


By W. F. Hume, D.Sc., F.R.S.E., A.R.S.M., F.G.S., Director of the Geological 
Survey of Egypt. 


f{\HE article which appeared by Dr. Ball in the Februarynumber of the 

GuorocicaL Macazine (pp. 71-6), strongly urging the origin of the 
Eeyptian Nile Valley as due to erosion rather than faulting, is the first 
public expression of a widespread feeling that the familiar rift theory 
is based on comparatively feeble foundations, and either requires 
strengthening or withdrawal. It must be remembered that when 
the Geological Survey of Egypt commenced its operations in 1896 the 
relation of deep African depressions to rifts was an accepted theory 
which had been found applicable in a number of striking instances. 
As one who has studied portions of the Nile Valley and the 
neighbouring deserts of Egypt for some years, I submit these few 
remarks, adopting a somewhat more personal point of view than is 
usual in papers of this nature, not from a desire for controversy, but 
because the subject is one worthy of discussion. 

During 1896 I was in frequent correspondence with Mr. Barron 
regarding Egyptian geology, and from his letters it was evident that 
two points had impressed him, viz. the absence of sand-deposits in 
the Eastern Desert and the abundant evidence of faulting. The 
widespread nature of these fractures seemed to me open to some 
doubt, but the first year’s work in the Eastern Desert (1897-8) led 
me in the main to adopt Mr. Barron’s views. The magnificent 
dislocations in the hills opposite Qena, and gigantic slip-faulting of 
Arras and Abu Had, north-east of that town, were too apparent to 
escape even superficial observation, and the discovery of the faulted 
areas described by Fraas, Barron, and myself near Qosseir, helped 
materially to strengthen the view that faults played an important 
part in the structure of the country. 

The investigations of 1898-9 in Sinai only tended to enhance their 
significance, and in a paper on the ‘‘ Rift Valleys of Eastern Sinai” 
I pointed out that a series of parallel valleys with the younger strata 
faulted between the older formations could only be explained as due 
to fractures arranged on some systematic basis. An attempt was also 
made to widen this conception so as to embrace the Gulf of Suez, 
Nile Valley, etc. 


DECADE V.—VOL. VII.—NO. IX. 25 


386 Dr. W. F. Hume—Origin of the Nile Valley. 


Thus far the evidence showed that disturbances of a tectonic nature 
were widespread in Egypt, that they had given rise to important 
surface features, but at the same time the rift or trough-fault view 
for the Nile Valley was not gaining the required basis of fact to make 
its position impregnable. The highly tilted gravel ridges south of 
Helwan, the long ridge of Gebelain in Southern Egypt, bringing up 
steeply dipping Cretaceous beds, the great slip-faults of the Qena— 
Luxor district could be invoked, but all these manifestations of earth- 
movement do not fit into a regular plan of trough-faulting, and for 
some years my colleagues and myself had, if I mistake not, abandoned 
(if we ever had them) any pronounced view as to the form of the Nile 
Valley near Cairo being directly influenced by faults. At the same 
time the great differences of structure between the two sides of the 
Nile both near Cairo and in the Qena—Luxor reach seemed to demand 
some explanation, which might be of wider character than mere 
erosion. 

Till 1900 I may frankly say that all my studies in the outer deserts 
of Egypt had biassed me in favour of a fault origin for the major 
portion of the Nile Valley; from that period onward the tide of 
thought took pause. Many visits to Nubia showed that faults were 
of minor importance there, while a study between Esna and Aswan, 
which was carried out on foot, every point of any interest within 
reasonable distance of the river being examined, further strengthened 
the view that in this reach of the river longitudinal faults were of 
no significance. On the contrary, transverse faults, such as the one 
at Kom Ombo, produce the most striking effects. The difference 
between the high Nubian Sandstone cliffs and hills on the right bank 
near Edfu, etc., and the comparatively low gravel ridges on the left 
or west bank, led to the view that the river was eroded along the 
original outcrop of the softer Cretaceous strata, to whose line of 
strike the present stream is roughly parallel. In 1906 satisfactory 
evidence was obtained of a transverse anticlinal roll in the hills 
south-east of Qena, a roll which in large measure explains the 
abrupt bend of the river at this point, along the outcrop of these 
Cretaceous beds. 

This does not, however, satisfy the problem to the full; we have 
still to explain the remarkable ravine of the Nile between Sohag 
and Assiut, and the north-westward bend near Cairo. For the latter 
feature it seems reasonable to suggest that the river has in the main 
taken advantage of the more easily denuded Upper Moqattam Beds, 
the geology of the two banks between Cairo and the Fayum differing 
geologically in marked respects. As regards the straight-lined ravine 
of the Nile, it is of interest to note that its long axis corresponds 
with a synclinal arrangement of the strata, which is also the cause 
of the marked differences between the two sides of the Nile south 
of Qena. AsI hope a general geological map of Egypt on a scale of © 
1: 1,000,000 will appear in the course of the late summer, there will 
be an opportunity for all interested in the subject to weigh the 
evidence and form their own opinions. 

The direction, therefore, in which my own views tend at the 
present time are put dogmatically. The southern portion of the 


Dr. W. F. Hume—Origin of the Nile Valley. 387 


Egyptian Nile from Aswan to beyond Qena owes its origin to denu- 
dation of the softer Cretaceous beds, as already suggested in the Cairo 
Scientific Journal. This view is, I believe, shared by Mr. Beaduell. 
Owing to the temporary dominance of a transverse roll near Qena 
the river has turned, following the direction of outcrop of these softer 
strata until its further course north-westward was determined by 
a well-marked syncline. North of Assiut a second fold may have 
determined the northward deflection of the Nile, the river breaking 
through where the Nubian Sandstone may have had an outcrop 
north of the Pyramids near Abu Roash. This conception is not so 
imaginative as might at first sight appear, there being an exposure 
of Nubian Sandstone in the Abu Roash Hills close to the river-valley.' 
The slipping of heavy masses of Eocene limestone on Cretaceous 
shales has exaggerated the fold effects in the region between Luxor, 
the slip-faults being often on a gigantic scale, but these presumably 
cannot be regarded as evidence in favour of true trough-faulting. 

So far as the Nile is concerned, therefore, I hold that folding plus 
erosion plus slip-faulting is sufficient to account for all the 
phenomena observed, a view still further emphasized by a recent visit 
to the desert plateau immediately north of the Qena depression. 
Here it is possible to study valleys in every stage of formation. The 
country is remarkably folded, though the individual dips seldom 
exceed 10°, and it is possible within a very short area to find evidence 
of the most varying causes of erosion. At the head of Wadi Gurdi 
the valley has obviously been formed along a cracked anticline; 
elsewhere synclinal folds have been responsible for the principal 
drainage-lines, whilst multiple small folds, like the waves of the sea, 
have determined many of the twists‘and turns. In addition to this 
complex folding, which was entirely unexpected, the rocks themselves 
are of a nature which specially lends itself to erosion by water. The 
lower part of the Eocene Series in this region is a white chalk, 
showing evidence of intense current-action. In these strata, caves, 
honeycombing of the limestone, natural bridges, and cylindrical 
channels, cut through the solid rock, testify to the intense activity 
of the erosive forces; while the deep ravines, which seam every part 
of this desert area, vie with the Nile Valley itself in the height of 
their bounding cliff-walls and the steepness of their sides. If it be 
remembered that the Nile Valley ravine is in its southern portion 
cut through these easily denuded materials, the conception of the 
erosion of the Nile Valley is not one which involves too great a tax 
on our imagination. 

When, however, we consider the origin of the Gulf of Suez, 
I must confess that I am not prepared to go so far as my friend and 
colleague Dr. Ball is prepared to do. Let us grant fully the broken 
anticline character of the Wadi Araba area; but what does that 
very admission involve? Why do the Miocene beds which are found 
north of the northern limb of this broken anticline (the North 
Galala Hills) pass across into Sinai, and only reappear again in the 
Eastern Desert of Egypt to the south of the southern limb of 


1 See Mr. Beadnell’s map of Abu Roash. 


388 Dr. W. F. Hume— Origin of the Vile Valley. 


the Araba anticline, while no Miocene strata have been found in the 
Araba depression itself? The evidence, as I read it, points to this 
region having been a domed area during Miocene times, and I can 
conceive of no erosive agent which would break across this great 
earth-feature without the intervention of fracture. Beit remembered, 
too, that the regularity of the parallel ranges (Gebels Esh, Zeit, etc.) 
further south is geologically more apparent than real. In the Esh 
range, as I pointed out in the Eastern Desert Memoir of 1897, on 
the westward flank of the hills, the strata follow one another in 
proper succession, dipping westward as the one-half of a regular 
anticline. To the east of its central cone of igneous rocks what 
appears? Except towards the northern end of the range none of 
these well-developed strata (from Nubian Sandstone to and including 
the Lower Eocene) are anywhere present, in their place being a high- 
tilted Miocene coral-reef. Surely such an inequality as this cannot 
be lightly passed over, and until good proofs to the contrary are 
submitted to me I consider that faulting and faulting alone can 
explain the phenomena. 

In Sinai the intensity of the faulting is so obvious that I await 
wider confirmation of its extent with equanimity, believing that the 
excellent effort made by Mr. Barron to unravel this most difficult 
problem will remain a permanent monument to his zeal and his 
industry. Very few would have done as much, or even a tithe as 
much, in the time at his disposal, and under the physical conditions 
which he was called upon to face. Only those who know something 
of the bitter cold of a Sinai winter, or the blinding sandstorms of the 
country between Suez and Tor, can appreciate his labours at their true 
value, and will be able to treat in a lenient spirit any errors of detail 
that may be revealed by subsequent close research in connexion with 
developing industries. As regards the eastern portion of Sinai, I have 
not one word to withdraw from the account of the rifts given in my 
memoir on that region, considering that the trough-fault view is the 
only explanation which satisfies all the conditions, geological and 
physical, presented by the parallel valleys of that complicated 
mountainous region. 

The conception which seems best to satisfy all the conditions of 
Egyptian geology appears to involve a major north and north- 
westward folding which in the oases, though marked, and in the 
first instance originating those depressions, has nevertheless only 
produced fracture effects to a minor extent. (This statement is 
necessarily relative, for those who have read Mr. Beadnell’s ‘“‘ An 
Egyptian Oasis’? will remember the important fracture-line determining 
the line of wells in Kharga Oasis.) 

In the Nile Valley erosion seems to have been the principal factor, 
the river either following the outcrops of the softer strata or the 
synclinal portions of the fold. The many fault-systems bordering it, 
especially on the east (Cairo—-Suez region, Helwan area, Qena—Luxor 
slip-fault district, Kom Ombo plain), are not in direct relationship to 
the present course of the river, or in the case of the great slip-faults 
only appear to be so, the limestones in the cliffs bordering the Nile 
slipping on and crushing the Cretaceous shales underlying them. 


Dr. W. F. Hume—Origin of the Nile Valley. 389 


For the Gulf of Suez, it seems difficult to explain the present 
conditions of its cutting through a gigantic dome, taken together 
with the inequilateral structure of the parallel ranges bordering the 
gulf, without invoking the aid of very serious fractures, whose 
activities are marked in most pronounced fashion on the peninsula 
of Sinai. ‘Thus we have an earth wave-system gathering strength as 
it passes from east. to west, the great trough being Egypt itself with 
its river in part marking the basin centre, while the wave-crest 
reveals itself in the serrated peaks and barren hills of the Eastern 
Desert and the wilderness of Sinai. Necessarily, as with the waves 
of the sea, this great system is broken into minor crests and hollows, 
domes rather than anticlines will be the rule, while curved fault- 
systems will surround them. All these features will no doubt become 
more and more marked as the detailed geological structure demands 
attention from economic or other reasons. In Sinai the north-west 
trend of the waves is replaced by a dominant north-eastward direction, 
but we know far too little of Northern Arabia to dogmatize as to its 
meaning and significance. A second, or transverse system of folds, 
is no doubt of great importance, and its true meaning will become 
more obyious as study proceeds, but as this involves work in regions 
difficult of access, or complicated in outline, progress will necessarily 
be slow, nor do these earth-movements bear prominently on the 
question. 

Briefly summarizing the point of view I at present hold— 

1. The main structure of Egypt is determined by two major fold- 
systems, one having dominant north or north-west trend, the other 
more or less transverse to this system. 

2. In the north-trending fold-system the wave-crests and troughs 
become more pronounced from west to east, finally resulting in 
fractures of the greatest geographical importance. 

3. In the depression containing the oases, comparatively gentle 
folding has resulted in the denudation of those portions where the 
anticlinal structure is most pronounced, fracture being unimportant 
as regards surface-features, though in Kharga of great moment for 
water-supply. 

4. The Nile Valley is regarded as due in the main to the com- 
bination of the north-trending fold, erosion of the softer Cretaceous 
strata in the southof Egypt, and the less resistant members of the 
Middle Eocene in Northern Egypt, the connecting Nile ravine 
following the axial line of the centre of the synclinal trough. 

5. The Gulf of Suez, though in direction determined by the 
dominant fold-trend, has required fracture for its full formation, 
there being possibly a minor fold region due to such fracturing 
between the Red Sea Hills and the main range of Sinai. 

6. In Sinai itself the fold-trend swings from north-west to north- 
eastward, and fracture-lines almost completely mask the original 
folds, which are only indicated by the trends of the gulfs and their 
parallel valleys. 


390 RL. M. Brydone—Chatk Polyzoa. 


II.—Norks oN NEW OR IMPERFECTLY KNOWN CHALK Potyzoa. 
By R. M. Bryponz, F.G.S. 
(PLATE XXX.) 
(Continued from the June Number, p. 260.) 


Ruacasostoma NovakiI, nom. noy. 


Syn. Wembranipora depressa, Novak, Denkschr. d. kais. Ak. d. Wiss. zu Wien, 
Math.-Naturw. Cl., Bd. xxxvii, p. 88, Taf. ii, figs. 9, 10. 

Novak considered this form within the range of variation of 
Cellepora depressa, Hag., but Canu’ recognizes it as a Rhagasostoma. 
It appears to be so closely related to a very distinct and persistent 
form which is very abundant and characteristic at Trimingham that 
I do not like to treat them as anything but two forms of a single 
hitherto unnamed species, and the form admirably figured by Novak 
must of course be the type of the species. 


Ruacasosroma Novak, mihi, var. Anetica, nov. Pl. XXX, Fig. 1. 


This is the above-mentioned form from Trimingham. It is dis- 
tinguished from Novak’s type by the squareness of the aperture, 
the much greater depth of the sinuses, and the general prevalence of 
a distinct inflexion of the sides of the aperture which makes the sinuses 
slightly bottle-shaped. The avicularia often show an interesting 
structure which would no doubt be found also in perfect specimens of 
Novak’s form; the sinus at the lower end of the aperture is closed by 
a narrow rectangular projection into the aperture just wide enough to 
seal up the sinus, and which is so deep-set as to appear to be not so 
much a process of the edge of the front wall as attached to its under 
surface. 

Very abundant at Trimingham; one specimen in zone of 
B. mucronata, Isle of Wight. 


CRIBRILINA CLAVICEPS, noy. Pl. XXX, Figs. 2-5. 


Zoarium always adherent. 

Zoecia very variable in size, length ‘68--9 mm., breadth 
*35—5 mm.; aperture variable in length and breadth, shaped like 
a keyhole, with a thickened margin round the upper part; what 
appear to be calcareous opercula may be sometimes seen inside the 
zocecia or even (Fig. 4) in situ; a pair of perforate tubercles often 
possessing a slight beak occur very regularly beside the aperture, and 
others occur somewhat irregularly on the edges of the front wall; — 
front wall slightly but decidedly keeled (Fig. 4), and showing ~ 
six or seven pairs of faint radiating imperforate furrows. 

Owcra not observed. 

Avicularia not observed except so far as the tubercles may be 
avicularian. 

Occurs regularly but sparingly in the Jf cor-anguinum zone at 
Gravesend and in Hants, and in the Marsupites zone in Hants. 


1 Bull. Soc. Géol. France, 1900, p. 428. 


R. M. Brydone—Chatk Polyzoa. ool 


CRIBRILINA FURCIFERA, noy. Pl. XXX, Figs. 6-8. 

Zoarium always adherent. 

Zoecia very variable in size, length ‘5-7 mm., breadth -4—"58 mm. ; 
aperture semicircular, with a stout perforated tubercle on either 
side, and generally two, sometimes three, and rarely four more 
slender perforated tubercles between them round the upper lip; 
the lower lip is much thickened, especially down the centre of the 
zoecium; its upper edge is primarily straight, but frequently 
develops a stout forked projection, the arms of which reach to 
a point where they partly overhang and appear to rest on, but do 
not in fact touch, the stout paired tubercles; at other times it 
develops a blunt denticle only; front wall generally highly arched, 
but varies down to almost flat as in Fig. 8, and covered with radiating 
ribs varying from very fine and numerous as in Fig. 6, to stout and 
few as in Fig. 8, the normal type with fairly fine and numerous ribs, 
only clearly distinguishable round the margins, being represented by 
Fig. 7; the furrows between the ribs are only perforated once, at 
their outer extremity. The side walls of those zocecia in which 
alone they are visible, i.e. those at the edge of the zoarium, are rather 
splayed and have large foramina in them, one of which, at the 
extreme upper end of the zocecium, is quite invariable in its 
occurrence. 

Owcia very large in proportion to the zocecium, of the globose type, 
but with a tendency to become slightly pointed, and with a strongly 
recurved free edge; they arise just above the pair of stout tubercles, 
but envelop the others. 

Avicularia. Small, depressed, slightly conical cells of irregular 
outline, with a sub-central rounded aperture and one or two large 
foramina in the front wall, such as may be seen in Fig. 8, occur 
sparingly but persistently, and may be in the nature of vicarious 
avicularia. 

This species is not uncommon in the IL. cor-anguinum and Marsupites 
zones of Kent and Hants, is common in the Act. quadratus zone of 
Hants and Sussex, and occurs also in the B. mucronata zone of Hants. 


Crrprinina Finiiozatr, nov. Pl. XXX, Figs. 9 and 10. 


Zoarvum always adherent, resembling that of C. furcifera. 

Zowcia small, length -58—-72 mm., breadth -4—"5 mm.; aperture 
circular, but with the lower one-fourth of its circumference cut very 
- sharply back so as to include an arc of a slightly larger circle; front 
wall gently arched, almost smooth, the radiating ribs and furrows 
which fix the generic position being almost obliterated; the outside 
zocecia show very regularly a large foramen almost at the head on the 
sloping surface above the aperture. 

Owcia very large, strongly resembling those of C. furcifera, but 
relatively rather longer and narrower, and with a stronger tendency 
to be pointed. 

Avicularia not observed. 

Occurs sparingly in the Act. guadratus zone in Hants. 

It will be observed that the last three species are none of them 
typical Cribritineg, and in two of them the furrows are wholly 


392 Professor E. H. L. Schwars—Fissure Volcanoes. 


imperforate. At the same time their. front walls are obviously of 
Cribrilinid type, i.e. built up from marginal spines more or less fused 
together, and it seems to me, as indicated at p. 292 of the volume of 
this Magazine for 1906, that in the Chalk it is not feasible to maintain 
one particular stage in the lateral fusion of spines as a separate genus 
Cribrilina, and that that genus must be enlarged to comprise all.stages 
of lateral fusion short of total obliteration of the spinous origin. The 
only alternative would be to create a new genus for all stages of 
lateral fusion except Cribrilina, as usually defined; such a genus would 
not admit of a positive definition, and is obviously undesirable. 


EXPLANATION OF PLATE XXX. 


'Fre. 1. Rhagasostoma Novaki, var. Anglica. Trimingham. x 12 diam. 
5, 2 ‘Oribrilina claviceps. Grayesend, Kent. x 12 diam. 
,, 8 Ditto, the same specimen. x 21 diam. 
,» 4 Ditto. Whitchurch, Hants. x 12 diam. 
»» . de, Ditto, Gravesend. x12diam.. . 
,, 6. Oribrilina furcifera. Andover, Hants. x 12 diam. 
», 7. Ditto. Bramford, Suffolk. x 12 diam. 
;, 8. Ditto.: Kingsgate, Kent.. x: 12 diam. 
5 9. Oribrilina Filliozati. Andover, Hants. x 12 diam. 
», 10. Ditto. West Tytherley, Hants. x 21 diam.. 


(To be continued.) 


' JIJ.—Tue Fissure Turory or VoLcanogs. 


By Professor E. H. L. Scuwanz, A.R.C.S., F.G.S., Rhodes University College, 
Grahamstown. 


R. HANS RECK has adduced an example of a voleano which, 
according to him, has been formed independently of a fissure. 
‘The volcano pierces the centre of a faulted block, the Herdubreid, 
Iceland, and on the vertical fault-faces there is no sign of any fissure.’ 
The example is probably unique in the world, and seems at first sight 
to negative the hypothesis that the escape of gases which tear through 
the earth’s crust and form the chimneys of volcanoes is in the first 
place initiated, by a fracture; on closer examination, however, the 
fact that the volcano stands in close relation to the faults which bound 
the horst, and the many cases which are known to occur where 
a fracture in the earth’s crust may be healed at the surface so that 
the rocks about the fracture are subsequently more resistant than 
before, seem to point to the Herdubreid volcano being a normal 
fissure-formed volcano, only that it stands in the same relation to the ~ 
fracture as a parasitic cone stands to the central crater. In other 
words, the chimney is an escape vent leading below the surface to one 
of the bounding faults of the horst. . 

The Herdubreid is a part of the north and south range of mountains 
made of palagonite tuff, which sinks towards the north below the 
level of the Odadahraun lava plateau, some 600 metres above sea- 
level, and on the south rises to 1077 metres. The Herdubreid ‘is 
1200 metres high, and is separated from the main range by a gorge 


1 Hans Reck, ‘‘ Ein Beitrag zur Spaltenfrage der Vulkane’’: Centralblatt fiir Min., 
Geol., u. Palaeont., 1910, No. 6, p. 166. 


Grou. Mae. 1910. PuaTE XXX. 


Bemrose, Collo. 


R. M. Brydone, Photo. 
Chalk Polyzoa. 


Professor E. H. L. Schwarz—Fissure Volcanoes. 393 


500 metres wide ; its walls are vertical, but the lower parts are hidden 
by debris. The square summit rises gradually to the crater, with its 
lavas of much more recent date than the palagonite tuff. The sub- 
structure of the volcano is shown in the four bounding fault-faces to 
a height of 700-800 metres above the accumulations of debris. On 
the north side there is a horizontal line where a darker and lighter 

material in the tuff meet; the whole length of the line is exposed, 
* and there is no trace of a dislocation. The material forming the 
basement of the horst is quite fresh on the exposed side, since the 
outer surface is rapidly weathering under the influence of frost, and 
the weathered material is removed by wind; this applies to all the 
four sides of the block, so that from all sides the evidence of the want 
of a fissure is perfectly clear. Dr. Reck concludes his article with the 
statement—It is therefore proved from observation that in one case 
at least a fissure does not extend under the basement of a volcano for 
a depth of from 300 to 400 metres. 

One of the best examples I know where a fracture in the earth’s 
crust has been healed is in the Berg River Hoek, near Paal in Cape 
Colony. I was called in to report on the nature of the valley with 
regard to its being suitable for a large reservoir. The site of the 
proposed retaining wall was traversed by a great fracture, on either 
side of which the rock, quartzite belonging to the Table Mountain 
Series, had been brecciated for 3 or 4 yards. I investigated the 
fracture very fully and found that the crush-breccia, through cementa- 
tion by secondary silica, had not only become very much more compact 
than the quartzite itself, but that the uncrushed rock beyond the 
crush-breccia had been also hardened by the deposition of secondary 
silica. The whole zone in the neighbourhood of the fracture was 
eminently suitable for the foundation of a retaining wall; not only so, 
but the cementing of the neighbouring rock showed that subsequent 
movement would not take place along the old fracture, but would 
have to find relief some distance away. 

Dr. Reck admits that all the volcanic fissures of the North of 
Iceland lie in a north and south direction, parallel to two of the 
bounding faults of the Herdubreid horst, so that it is at least admissible 
to those who believe in the fissure theory of the origin of volcanoes to 
consider the Herdubreid chimney to be an offshoot of a volcanic fissure, 
the surface end of which has been closed by cementation. 

Daubrée’s experiments on the exploding of dynamite in steel shells 
shows us how a fissure may allow the escape of gases, and that these 
in tearing their way to the surface may drill cylindrical holes; the 
minute fracture in the case of the shells need not have extended to the 
surface. I have in mind, however, what I have termed a fossil earth- 
quake, where a spherical mass of dolerite has been shot off from 
a horizontal sheet of that rock and has drilled a hole vertically 
through the overlying shale for a height of 15 feet. The example 
is at Cradock in Cape Colony. The cause for the ejection was 
probably that the molten rock encountered a reservoir of water, and 
in the explosion which followed a portion of the dolerite was projected 
upwards. The space where the projected mass of rock once was, and 
the path of the projectile, are filled with crushed-up shale. I call it 


394 ' A. Wade—Formation of ‘Dreikante’. 


a fossil earthquake because the jar the explosion must have given to 
the earth’s crust must have produced a quite appreciable earthquake 
at the time of its occurrence, but in the present instance it is 
interesting as an example where a perfectly circular vent may be 
drilled. through the rocks by means of the eruption of volcanic 
material without a fracture, but this only occurs where the molten 
rocks come sufficiently near the surface of the earth’s crust to allow 
the explosion of gases. The Cradock fossil earthquake is in direct 
connexion with a fissure filled with dolerite which was once molten, so it 
seems to me probable that the Herdubreid volcano likewise is con- 
nected with a volcanic fissure rather than that it should have pierced 
the whole thickness of the solid earth’s crust down to where some 
reservoir of molten material might have existed. 


I1V.—On tHe Formation oF DREIKANTE IN Desert REGIONS. 
By A. Wave, B.S&c., A.R.C.S., F.G.S. 


(PLATES XXXI AND XXXII.) 


HEN one considers the part Britons have played in exploring 
and investigating the various desert regions of the world, one 
is surprised at the relatively small amount of literature that there is 
in the English language dealing with the phenomena which are 
peculiar to desert conditions. Many hazy, and even erroneous, ideas 
are still held with regard to the processes at work and the effects 
produced by the various agents of denudation. 
The three-edged stones known as ‘dreikante’, which are so 
characteristic and abundant in most desert regions, have been 
subjected to little careful investigation whilst in actual process of 
formation, and many ideas which appear to be incorrect are current 
with regard to their mode of origin. 

Originally it was thought that they had been cut by river action, 
or by the movements of sand in the beds of rivers. Steenstrup 
proved that this was impossible,! and it is now known that they are 
essentially the products of wind-blown sand. In shape they usually 
resemble very closely a Brazil nut, and it is commonly thought that 
this characteristic form is produced as follows. 


Wine, il, 


The travelling sand-grains strike a stone or a pebble lying on the 
desert. They are in consequence divided into two streams which pass 
along the sides of the object, wearing away the sides and producing 
a pointed snout to the pebble and a sharp ridge along the crest. 
(See Text-fig. 1.) It is difficult to see, however, why the ridge 
should remain equally sharp from front to back, and why the end 


1 Geol. Foren. Stockholm, x, p. 485 ; xiv, p. 498. 


. Maa. 1910. 


Pebbles from the Eastern Desert of Egypt, showing the gradual evolution of the 


‘dreikante ’ by the abrz n of wind-bl ad from the earlier stages to 


the la 


A. Wade—Formation of ‘Dreikante’. 395 


opposite to the point from which the wind usually comes should be 
just as pointed as the other. It is inconceivable that the deflected 
currents of sand-grains would keep so closely to the pebble from 
end to end. One would expect a pointed front and a more or less 
unworn end. This, however, does not occur. It seems therefore 
that this explanation is not quite satisfactory in its nature. 

During 1909 I spent a good many months on the Eastern Desert of 
Egypt, and it occurred to me to make a careful examination of the 
dreikante, which are so abundant in the stony desert tract which 
stretches between the Red Sea Hills and the coast. 


a= 
ae 
aes 


Fic. 2. Types of ridge-curves in dreikante shown in plan. The type figured in 
No. 3 is often so modified at each extremity by branching that instead of having 
two upper faces the dreikante has four. 


The dreikante are usually formed from quartz pebbles derived from 
the Nubian Sandstone, but flints from the Eocene, granites and 
porphyries from the mountains, and some dolomitic limestone also 
furnish supplies. The most perfect examples are produced from the 
quartz pebbles and from a fine-grained red felsite. 

The locality is almost an ideal one for such an investigation, since 
the wind blows almost invariably from one quarter (north, or a little 
west of north). At the outset I was struck by the fact that the long 
axes of the dreikante were not usually set in the direction of the 
prevailing wind. This led me to work carefully and systematically 
over a limited area. I marked out a portion of fairly level desert, 


396 A. Wade—Formation of ‘Dreikante’. 


something under half a square mile in extent, and noted with regard 
to all the dreikante I could find exactly how they were situated with 
regard to the wind. I noted between 300 and 400 specimens, and 
found that.78 per cent. were set approximately at right angles to the 
direction of the prevailing wind, whilst only 22 per cent. were set 
approximately parallel: to that direction. Evidently the theory 
already stated will not account for these facts. Moreover, not all 
the wind-worn pebbles were three-edged, though there seems. to be 
a tendency towards the Brazil-nut shape in the late stage of erosion 
in all cases. ‘ . jd 

Stones were found in all stages, from the well-rounded, water-worn 
pebbles from the Nubian Sandstone (Pl. XXXI, Fig. 1), or angular 
flints and broken pieces of igneous rock, showing only incipient traces 
of the abrasive action of the wind-blown sand, to dreikante, worn 
down until almost level with the surface of the desert (Pl. XXXI, 
Figs. 7 and 8). The series shown in Pl. XXXI, Figs. 1-8, gives an 
almost complete ‘life’ history of the dreikante from the earlier stages 
to the last. 

The ridge along the crest is rarely a straight line, but is more 
usually a more or less delicate curve. In the Text-figure (Fig. 2) 
Nos. 1 and 2 are the more usual types of curve. The side of the 
stone facing the wind is always beautifully smoothed and polished, 
presenting a clean, fresh surface to the wind. Frequently this face 
is the only one showing signs of cutting by the sand, the remainder of 
the pebble showing the original water-rounding, and is also usually 
stained, probably with iron oxide. This shows that in such cases the 
pebble has not been moved by the wind since it was exposed to the 
action of blowing sand, for if such had been the case other faces would 
have been cut upon it. Such pebbles usually present a ridge-line 
like Text-fig. 2, Nos. 3 or 4. 

The face presented to the wind is not a plane surface, but is also 
gently curved. Measurements taken from over fifty specimens showed 
that this surface makes an angle with the vertical which varies 
between 40° and 50°. It most usually approximates to 45°. The 
curve is shown in Text-fig. 2, No. 4. 


va 


a 
[See 


aes / 


--~ 
/ 


TGs, a. 


We are now in a position to consider how the dreikante have been 
formed. Evidently in most cases the travelling sand-grains do not, on 
encountering a pebble, split into two currents which travel along the 
sides of the stone and so form aridge. Instead of this they tend to 
move upwards over the pebble with an eddying motion. The curve 
produced nearest the ground is always convex towards the wind. 


Grout. Mac. 1910. PLATE XXX 


i 
ve rn 
« 


pod 


‘omy 


° 


: oak 
2 ee # 
in eee mag 


A. Wade—Formation of ‘Dreikante’. 397 


(See Text-fig. 3.) This is probably explained by a zone of com- 
pression in the air at this point causing most of the grains to rise a little 
before they would otherwise do so. They apparently glide upwards 
over this zone ina path which is convex towards the wind. The action 
of the wind drives them forward against the face of the stone from 
which they rebound, describing what appear to be parabolic curves. 
The large dreikante shown in Plate XXXII is an excellent example, 
showing beautiful wind-cut curves. 

It seemed to me that from a measurement of these curves one might 
be able to deduce some law with regard to the action taking place. 
I attempted the task, but though I was able to prove that they were 
parabolic, I was unable to obtain any good result, probably. owing to 
the inaccuracy of my methods in transferring the curves on the faces 
of the stones to paper. This proved to be a task requiring very 
delicate instruments. There seemed, however, to be some similarity 
between the curves from the faces of different specimens, and it should 
be possible, I think, to obtain from them a measure of the velocity of 
the wind and the energy expended in erosion. The presence of stones 
and pebbles near to one another cause various modifications of the 
simple case. Side currents, eddies from other stones, all produce these 
effects, and these can be traced on the dreikante under consideration 
when examined in situ. 

But how are we to explain the Brazil-nut shape? The cutting 
away of one face only is not enough to do that. The cutting away, 
however, continues until the pebble stands on a very narrow base in 
almost unstable equilibrium. A little extra wind and it is blown 
over, and the cutting commences again on a fresh side. Evidences of 
this are quite common on the desert. Sometimes at night the ratthng 
of the pebbles moving under the action of a high wind is very con- 
siderable. ‘The five-faced pebble shown in plan in Text-fig. 4 could 
not be explained by the earlier theory. It was originally a partly 
developed dreikante which has been twisted at right angles to its 
original direction and the abrasive action continued. 


Fic. 4. 


Most of the well-developed dreikante show a kind of spiral twist 
in the direction of their long axis. This appears to show that the 
path of a particle in a wind eddy is not a very simple curve. There 
are a good many curiosities in the formation of dreikante which are 


398 Dr. H. Woodward—Supposed Pholas-borings, Fayim. 


certainly produced by the action of eddies. They would probably 
produce interesting results when studied by a well-trained physicist 
on the spot. The last stage in the formation of dreikante is reached 
when the pebble is reduced to an almost flattened little plate, which 
is sooner or later reduced in size to a mere sand-grain. Again, one 
can observe this reduction in all stages on the desert. Actual experi- 
ment with laboratory conditions proved that these three-edged stones 
could not remain with their pointed ends facing a strong air current, 
but that they invariably tended to set themselves broadside on towards 
it. This is consistent with the explanations given above, and to some 
extent confirms them. 
The following short bibliography will perhaps be useful to those 
who are interested in these-and other kindred phenomena :— 
1. J. Warrner. ‘ Uber Ergebnisse, einer Forschungsreise auf der Sinaihalbinsel 
und in der Arabischen Wiiste’’: Verhandl. den Ges. f. Erdkunde z. Berlin, 
1888, Bd. xv, No. 6. 


—— ‘‘Die Denudation der Wiiste’’: Abhandl. math.-phys. Classe d. Konigl. 
Sachs. Ges. der Wissensch., Leipzig, 1891, vol. xvi, pp. 847-569. 


bo 


3. —— ‘ Das Gesetz in Wustenbildung in Gegenwart und Vorzeit’’ ; Berlin, 1900. 
4. J. H. WoopwortH. Amer. Journ. Sci., 1894, xlvii. 
5. Verworn. ‘‘ Sandschliffe von Djebel Naktis, ein Beitrag zur Entwickelungs- 


geschichte der Kantengerolle ” : Neues Jahrb., 1896, i, p. 200. 

6. E. Harz. Compt. Rend. Géol. Soc. France, 1900, p. 30. 

7. O. Aner, Jahrb. k. k. Geol. Reichs., 1902, p. 24. 

8. Srrenstrup. Geol. Foren. Stockholm, x, p. 485; xiv, p. 498. 

9. M. Cuotsy. Docwments relatifs a la Mission dirigée au Sud de 1’ Algérie, 
1890, p. 327. 

10. T. Barron & W. F. Hume. Topography and Geology of the Eastern Desert 
of Egypt ; Cairo, 1902. 

See also F. A. Bather, ‘‘ A wind-worn Pebble in Boulder-clay,’’ Guon. Mae., 
1905, p. 858; and ‘Wind-worn Pebbles in the British Isles, etc.’’, Proc. Geol. 
‘Assoc., vol. xvi, pp. 896-420, pl. xi, 1900 (with references to eighty -seven papers on 
dreikante and other wind- -polished stones). 


V.—Own soME SUPPOSED PHOLAS-BORINGS FROM THE SHORES OF BIRKET 
EL Qurotn, THE ANCIENT Lake Moents, or THE Faytm, Eeyrr. 


By Henry Woopwarp, LL.D., F.R.S. 


N a review of Mr. H. J. L. Beadnell’s important Memoir on the 
Topography and Geology of the Faytm Province of Egypt, 
published by the Egyptian Geological Survey in 1905,! I briefly 
referred in passing to some “curious blocks of sandstone, pierced by 
numerous borings’’, described by the author, and I added, ‘“they 
appear to be the exact replica of specimens brought home from Lake 
Tanganyika by Mr. J. E. 8. Moore” (p. 519). 

Mr. Beadnell writes in his memoir at p. 71—‘‘ Borings on Rock- 
surfaces; of doubtful age. There are within the Faytim depression 
numerous rock-surfaces pierced by borings, apparently the work of 
marine boring mollusca but naturally offering no exact evidence as 
to their age and origin. These borings are found at two distinct 
levels, approximately from zero to 20 metres above sea-level and at 
112 metres above sea-level. 


1 See Guo. Mac., 1905, pp. 516-19. 


Dr. H. Woodward—Supposed Pholas-borings, Fayim. 399 


‘“‘(a) Low-level borings. Between Tamia and Dimé, near the eastern 
end of the Birket el Qurin, the lowest ground, consisting of poor sandy 
land with tamarisk scrub, bordering the lake and cultivation [ the lake | 
is bounded by a low escarpment of beds of the Birket el Qurun Series. 
Along certain horizons one or more beds of calcareous sandstone 
weather into large globular masses, which, as already pointed out, are 
in reality huge concretions,' but which may have been further rounded 
by water action. The chief point is, however, the fact that these 
blocks are honeycombed in the most remarkable way by beautiful 
examples of borings; their presence was first noticed by Schweinfurth. 
The globular masses of sandstone, often several feet in diameter, are 
worn on the surface into a number of parallel ledges, each of which is 
perforated by countless numbers of vertical holes, averaging 10 mm. in 
diameter (maximum 15mm.), placed at right angles to the ledges; 
these holes are not, as a rule, connected from one ledge to another. 
They occur in every stage of perfection, from hollows as small as the 
finger-tips and only a few millimetres deep to long complete chambers 
which generally show considerable tapering, and are often placed so 
close together that the dividing wall is pierced [see woodcut ]. 


“Block of sandstone pierced by numerous borings,’’ reproduced from Mr. H. J. L. 
Beadnell’s Topography and Geology of the Fayim Province of Egypt (Cairo, 
1905), p. 72, fig. 7. 


“‘ At El Kenisa, a promontory jutting out into the lake, sandstones 
showing shell-borings occur at a height of 14 metres above sea-level. 
Between Dimé and the lake a calcareous sandstone contains many 
borings, 66 metres above the lake-level or about 22 metres above 
sea-level. 

(6) High-level borings. Further west, but at a considerably 
higher level, borings are again met with. In this case a hard compact 
limestone, forming a dip-slope surface on the top of the lower cliff of 
the Qasr el Sagha Series, was found pierced with borings, similar in 
character to those of the lower level. The exact locality where these 
high-level borings were observed is 14 kilometres west of the western 
end of the lake and 16 kilometres north-east of the eastern extremity 


1 See infra, p. 401. 


400 Dr. H. Woodward—Supposed Pholas-borings, Fayiim. 


of Gar el Gehannem. The height was determined as 156 metres 
above the Birket el Qurin, or 112 metres above sea-level, and we have 
every reason to believe these figures to be approximately correct. 
Up to the present time borings at this altitude have not been met with 
in any other locality.” 

In Mr. J. E. 8. Moore’s book Zo the Mountains of the Moon, 
Tanganyika Expedition, 1899-1900 (published 1901), p. 160, the 
author writes—‘‘The water's edge [of Lake Kivu] is generally 
fringed with bushes and ¢all reeds, which grow thickly together, and 
the land rises so steeply into the grass slopes behind that it is 
exceedingly difficult to get on shore at all from a boat. In conse- 
quence of this peculiar character of the shores there are hardly any 
places where there are sand-beaches or rocks, and it was only after 
I had been paddling about for an hour, and scanning the innumerable 
islands with my glasses, that I saw a low rocky shore on the left, on 
which I landed. It was a most extraordinary place, backed up by 
a steep green hill. The rocks which I had seen consisted of strange 
rounded masses like the surface of a pudding, and, wherever they were 
wet by the ripples of the lake, were covered with green Cladophora and 
slime, and in places they rose up into weird stony trunks, like those 
on the old coral beaches one sees about Mozambique. These upstanding 
lumps were, moreover, pierced with holes, as if they had been prepared 
for blasting operations, and for the life of me I could not find out for 
a long time what they were or how they had been formed. When 
I broke off a portion, moreover, I found to my intense surprise that 
the stone was full of fossil shells; there was an unmistakable planorbis 
and some conical forms, probably melanias. But what animal had 
bored the long straight holes, about an inch in diameter, which ran 
parallely through the mass? I could not make this out, but after 
a time I found one mass with an old partially fossilized reed-stem 
filling up one of the holes, and then the mystery was suddenly solved. 
The holes were the casts, in a lake deposit of some kind, of reeds that 
had once grown there. That this was so soon became certain, for 
I found several clumps of old dead reed-stems already becoming 
covered up with a curious incrustation from the waters of the lake 
which forms about them, and other similar structures. In other 
places this substance, which turns out to have a high percentage of 
carbonate of magnesium, binds the loose pebbles of the shore into 
masses of conglomerate, which are as hard as if they had been made 
of Roman cement’’ (p. 160). 

Having been so fortunate as to haye seen and examined the 
specimen sent home by Mr. Beadnell and figured above, and also 
the hand-specimen from Lake Tanganyika obtained by Mr. Moore, 
I may venture to pronounce upon the identity in their character, and 
to express the opinion that the perforated blocks from the Faytm are 
not the work of boring mollusca in rock, but that the sandy calcareous 
material, which is similar to that from Lake Tanganyika, has been 
accumulated around the stems of reed-like water-plants as a more or less 
concretionary deposit precipitated from the waters of the present lake 
or from those of its more extensive predecessor, Lake Moeris, around 
the shores of which grew in abundance large clumps of these tall reeds 


|, 


Dr. H. Woodward—Supposed Pholas-borings, Fayim. 401 


with hard siliceous stems,' the final decay of whose upright stems have 
left the hollow cylindrical cavities which suggested to my friend, 
Mr. Beadnell, the resemblance to the crypts of boring Mollusca. 

Dr. C. W. Andrews, F.R.S., who has paid several visits to the 
Faytim in search of fossil mammalia, informs me that the tall Arundo- 
like reeds always grow in large clumps along the margin of the lake, 
and that the huge concretions, or globular masses of sandstone— 
honeycombed with vertical borings—represent in all probability the 
actual bases where these reeds formerly grew. 

He suggests that the accumulation which had been originally 
formed in the interstices between and around their thickly growing 
reed-like stems, was largely composed of the fine grains of sand-dust 
blown by the prevailing winds, and which had since become solidified 
into a concretionary sandstone by the addition of calcareous and saline 
matter contributed by the waters of the lake itself. 

On this point Mr. Beadnell observes (p. 13, op. cit.): ‘‘ Although 
under the present desert conditions practically no material from the 
surrounding desert is washed into the lake, doubtless a considerable 
amount of fine dust and sand is carried into it by the wind, especially 
during the violent sandstorms which occur frequently in the locality. 
The high cliffs which bound the northern shore of the lake, throughout 
a portion of its length, probably have the effect of checking the 
velocity of both north and south winds, thus causing a considerable 
amount of sand, which would otherwise be carried across, to be 
dropped on its surface” (p. 14). 

The occurrence of these globular masses of concretionary sandstone, 
perforated by countless numbers of vertical holes, at different levels, 
both at and above the present margin of the lake, is readily explained 
as being due to the gradual shrinkage of the level of the lake,? which . 
is constantly going on from evaporation and supposed underground 
outlets, and this, together with the quantity of water absorbed by 
the large area (1800 kilometres) under cultivation in the Faytm, is 
probably in excess of that received by the Bahr Yusef Canal, the 
natural inlet from the Nile. 

The vast proportion of perforations made by Saaicava and by 
LInthodomi generally, penetrate the rock in all directions, and offer 
no very close analogy to these usually straight, tubular, parallel, closely 
arranged hollows. 

But the crypts of Pholas erispata are at times more regular, often 
forming extensive colonies, and the animals, in burrowing, less seldom 
invade one another’s retreats. They commence as quite small crypts, 
but as the molluse increases in size and the perforation deepens, it 
expands its chamber /aterally, which, seen in vertical section, becomes 
somewhat flask-shaped with a slender neck. The lower end is 
rounded and has the largest diameter. Should the boring mollusc 
pass through the ledge and so expose the lower extremity of the 


1 See pl. xvi. View near the western end of the Birket el Qurin, also view of 
the north side looking west, pl. i, in Mr. Beadnell’s Memoir on the Topography and 
Geology of the Fayim Province of Egypt (Cairo, 1905). 

* Now occupying only 225 square kilometres, the whole area of the Fayim 
depression, much of which was once a lake, covering about 12,000 square kilometres. 


DECADE V.—VOL. VII.—NO. IX. 26 


402 Dr. A. Smith Woodward—Fossil Fishes from Egypt. 


animal, it pays the penalty with its life. Most of the perforated 
blocks from the Fayim show the burrows passing completely through 
the masses. 

Pholades generally occur between tides from high to low water. 
Their burrows always hold sea-water, which is renewed with each 
tide. The Pholas is assisted by the grains of sand brought by each 
tide to bore downwards into the rock with its foot and so deepen its 
burrow. It is most improbable that Pholades could exist in a lake, 
however salt, as they require tidal action to carry on their existence. 
Mr. Beadnell writes, op. cit., p. 14: ‘‘The phenomenon of the 
extraordinary freshness of the Birket el Qurin has been commented 
on by Schweinfurth, who shows that the degree of concentration of 
salt in a lake whose volume has been continually reduced, and to 
which salt has constantly been added, should be many times greater 
than the actual existing amount.’’ An analysis’ of the water at the 
west end of the lake (where the concentration is greatest, owing to 
the distance from the feeder canals) showed that the total salts 
amounted to only 1°34 per cent., of which 0°92 per cent. was sodium 
chloride. 


VI.—On a Fossiz Sore anp A Fosstn Ext From tHE Eocene 
or Eeyrr. 


By Artuur SmitH Woopwarp, LL.D., F.R.S., of the British Museum 
(Natural History). 


(PLATE XXXIII.) 


WO well-preserved Teleostean fishes from the Eocene Limestone of 
Tura, between Heluan and Cairo,’ have been submitted to me 

by Dr. W. F. Hume, Director of the Geological Survey of Egypt. 
They apparently represent new species, but, like most fishes of Eocene 
age, they are remarkably modern in type, and one seems to be referable 
to an existing genus. With them were found remains of two species 
of Percoid fishes, which are scarcely sufficient for exact determination. 


1. Sonea EocEenIca, sp.nov. Pl. XXXIII, Figs. 1, 1a, 6. 


A small fish measuring 5:7 cm. in total length is a true Pleuronectid, 
and may be compared with the diminutive species of Solea, already 
known from the Lower Miocene of Wiirtemberg.? As shown by 
Pl. XXXIII, Fig. 1, the upper part of the anterior half of the 
specimen is broken away, but otherwise it is completely exhibited in 
direct left side view. 

The head with opercular apparatus occupies somewhat less than 
one-quarter of the total length to the base of the caudal fin. The 
maximum depth of the trunk must have equalled slightly less than 
half of this total length. Some of the head-bones are distinct and 


1 A Preliminary Investigation of the Soil and Water of the Fayim Province, 
by A. Lucas, Survey Department, Cairo, 1902. 
2 W. F. Hume, ‘‘ The Building Stones of Cairo Neighbourhood and Upper 
Keypt”’: Geol. Surv. Egypt, 1910, p. 44. 
' 3 Solea kirchbergana, H. von Meyer: Paleontographica, 1851, vol. ii, p. 102, 
pl. xvii, figs. 2, 3; also loc. cit., 1856, vol. vi, p. 25, pl. 1, fig. 3. 


Dr. A. Smith Woodward—Fossil Fishes from Egypt. 403 


can be readily identified (Fig. 1a). Below the base of the skull (c.) 
the pterygo-quadrate arcade is seen, the ectopterygoid having a 
thickened and sharply bent oral margin, and the relatively large 
quadrate (quw.) inclined forwards. The long and gently arched 
maxilla (mx.) has a large articular head in front and is slightly 
expanded at its hinder end. The slender, parallel premaxilla (pmz.) 
completely excludes this bone from the margin of the mouth. The 
mandibular ramus is short and deep, triangular in shape, with the 
dentary (d.) and articulo-angular (ag.) taking about equal shares 
in its constitution. The only teeth clearly distinguishable are very 
minute points on the oral border of the dentary. The pre-operculum 
(pop.) is sharply bent, with the upper and lower limbs of equal size, 
each tapering to a point. Its hinder border is rounded at the angle, 
and its smooth outer face is marked with four large openings into the 
slime-canal. he small operculum and sub-operculum are somewhat 
displaced, and there are traces of about six branchiostegal rays below. 
Nine vertebre can be counted in the abdominal region, and two of 
the centra exhibit the lateral median longitudinal ridge. The minute 
ribs cannot be seen, but the large hypapophyses are conspicuous below 
the six posterior centra, slightly i increasing in size backwards. There 
are twenty-two caudal vertebre, and the neural and hemal arches are 
long and'slender. The hindmost caudal centrum bears the complex 
of hemal and neural arches for the support of the caudal fin shown in 
Fig. 16. The long and slender left clavicle is well seen (Fig. 1a, cl.), 
bent forwards at its upper end, slightly expanded below, and there 
are traces of the pair of small rod-shaped pelvic fin-supports (plv.) 
among the scales postero-inferiorly. The rays of the paired fins are 
not recognizable with certainty, but the anal and caudal are well 
displayed, and the hinder part of the dorsal is also seen. The rays 
of the anal and dorsal fins are remarkably slender, and those of the 
anal are thirty-six or thirty-seven in number. The foremost anal 
fin-support is a long curved bone forming the hinder border of the 
abdominal cavity. The caudal fin, which is rounded, comprises about 
eighteen rays, of which the first three at the origin above and below 
are short and comparatively stout, closely adpressed and gradually 
increasing in length. The principal caudal fin-rays are distantly 
articulated and bifurcate distally. The trunk is completely covered 
with a dense squamation, which seems to extend slightly over the 
base of the dorsal and anal fins. Though not easily observable, the 
scales are evidently antero-posteriorly elongated, and there are some- 
times traces of a fringe of slender denticulations at their hinder 
border. 

As already suggested, the fish now described is most closely similar 
to the small Solea kirchbergana trom the Lower Miocene of Wirtemberg, 
and, like that species, it appears to differ only from the typical 
existing Solea in the comparative shortness of ‘its caudal region. 
In the latter respect it corresponds with the allied existing genus 
Achirus, which has curiously modified pelvic fins.’ As, however, the 


’ D.S. Jordan & D. K. Goss, ‘A Review of the Flounders and Soles (Pleuro- 


nectidze) of America and Europe’’: Ann. Rep. U.S. Fish. Comm. for 1886 (1889), 
p. 308. 


404 Dr. A. Smith Woodward—Fossil Fishes from Egypt. 


jaws and the tail of the new fossil are proved to agree exactly with 
those of Solea itself, while the condition of the pelvic fins is uncertain, 
it may best be placed in this genus. It is distinguished from all the 
known species by its shape and by the number of its caudal vertebrae 
and anal fin-rays. It may therefore be named S. cocenica in allusion 
to the fact that it is the first example of its genus to be obtained from 
a formation so old as the Eocene. 


2. Mytomyrvs FRANGENS, gen. et sp. nov. Pl. XXXIII, 
Figs. 2, 2a-c. 

An eel measuring about 31cm. in total length is well displayed 
from the right side, and lacks only the anterior part of the snout 
(Fig. 2). The length of the head with opercular apparatus equals 
about twice the maximum depth of the trunk, and is contained six 
times in the total length of the fish. 

The crushed hinder half of the skull (Fig. 2a) shows that it is of 
the usual elongated, narrow, and depressed shape, with a prominent 
postfrontal bone (pif.); and in the middle of both upper and lower 
jaws there is a single regular series of very large grinding teeth, 
which are enamelled, smooth, rather deep, and flattened at the apex. 
A more slender blunt tooth is seen near the symphysis of the mandible. 
The thin smooth operculum (op.) exhibits a horizontal strengthening 
ridge on its inner face. Traces of very slender branchiostegal rays 
(dr.), not curving upwards round the operculum, are seen below. 
There are thirty-three vertebre in the abdominal region, with con- 
stricted centra which are strengthened by a few slight longitudinal 
ridges. In about the twelve foremost vertebrae the neural spines (7.) 
are much expanded, the two first also comparatively deep, but further 
back they soon become slender rods lke those of the caudal region. 
The broad triangular transverse processes are preserved both in some 
of the foremost and five of the hindmost abdominal vertebre, and 
there are also some traces of short delicate ribs. There are about 
sixty-seven caudal vertebrae, with similar but more elongated centra, 
and very delicate neural and hemal spines. The terminal vertebra 
bears a small fan-shaped expansion, suggestive of a hypural bone. 
In the pectoral arch the supraclavicle (sc/.) is a relatively long and 
slender bone, nearly reaching the occiput; and the almost equally 
slender clavicle (¢l.) bears in its upper half a delicate and much- 
expanded scapular arch, of which the coracoid (co.) forms the largest 
share. Of the pectoral fin only an obscure impression of the base 
is shown. The median fins are remarkably deep, continuous round 
the tail, with all the rays subdivided and distantly articulated in their 
distal half. The dorsal fin arises immediately above the scapular arch 
and comprises about ninety rays. The expansion at the end of the 
terminal caudal vertebra bears eight or nine comparatively crowded 
rays. The anal fin, which extends as far forward as the end of the 
abdominal region, consists of about sixty-five rays. The median fin 
must have been continuous round the end of the tail, but the space 
separating the terminal group of crowded rays from the last dorsaland . 
anal rays respectively is greater than that between any two other 
fin-rays (Fig. 26). There are no traces of scales in the lower part of 


ae dur WeUIM ah “ASO, 


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“YL ITEP P 


TIX XY Id “TA TA A 2pe99G ‘OL6E Sept 1995 


A. LT. Leach—Bagshot Beds, Shooters Hill, Kent. 405 


the abdominal region, but above the vertebral column there are remains 
of calcifications along the lateral lme; while both here and over the 
whole of the caudal region there is a curious mottling (Fig. 2c) 
suggestive of a fine and delicate squamation. 

Though in all respects a typical eel, the fossil now described 
evidently represents one of the more generalized and primitive forms 
of the group. Its relatively large supraclavicle, its conspicuous 
hypural bones, as well developed as those of a very young Anguilla,' 
and its extensive squamation, are all characters of low degree. The 
relatively great depth of its dorsal and anal fins is also noteworthy. 
Among known primitive eels it is distinguished by its large and 
powerful crushing teeth, and it may therefore be referred to a new 
genus under the name of Mylomyrus. The species, defined by its 
general proportions and by its vertebral and fin formula already 
detailed, may be known as I. frangens. 


EXPLANATION OF PLATE XXXIII. 


Fic. 1. Solea eocenica, sp. nov. ; fish nat. size, with head (1a) and caudal fin (16) 
enlarged three times. ocene: Tura, near Cairo. 

Fic. 2. Mylomyrus frangens, gen. et sp. nov.; fish one-half nat. size, with (2a) 
head, etc., nat. size, (20) caudal fin enlarged twice, and (2c) portion of 
trunk showing scales, enlarged twice. Ibid. 

ag. articulo-angular; 67. branchiostegal rays; cl. clavicle; co. 
coracoid; c. cranium; d. dentary; mz. maxilla; m. neural spine; 
op. operculum; plv. pelvic fin-supports; pmzx. premaxilla; pop. pre- 
operculum ; ptf. postfrontal ; gw. quadrate; sc/. supraclayicle. 


VII.—Norte on a SEcrron IN PROBABLE BacsHot Brps on SHOOTERS 
Hirt, Kent. 


By A. L. Lzacu. 


N 1905 trenches for electric mains were carried up the north- 
eastern slope of Shooters Hill, along Shrewsbury Lane to ‘‘The 
Bull”, and thence down the western hill-slope along the Dover Road. 
From about 350 O.D. in Plum Lane to 424 O.D. at ‘‘The Bull” the 
trench ran for nearly two-thirds of a mile along the junction of the 
London Clay with the overlying group of sands, pebbles, and clayey 
gravels which form the ‘ gravel cap’ of Shooters Hill. Neither the 
exact age of these superficial deposits nor their mode of formation— 
whether marine or fluviatile beds—is as yet known, but the general 
coarseness of the sands, the presence of pebbles of Lower Greensand 
chert, and the very stiff clayey matrix of the gravel distinguish them 
from typical Bagshot Beds, and moreover throughout the greater part 
of the section a sharp and irregular junction could be traced between 
them and the brown London Clay. At a few points, however, 
the top of the London Clay was seen to pass into pale-brown and 
yellowish sandy clays, sometimes of significant thickness. Thus in 
the Dover Road, about 100 yards above Christ Church, below the 
thick red clayey gravel of the ‘cap’, lay about 3 feet of yellow loam, 
the lower part of which became a pale-brown clay passing quite 


1 J. A. Ryder, ‘‘ On the Origin of Heterocercy’’: Ann. Rep. U.S. Fish. Comm., 
1884 (1886), p. 1051, pl. iv, fig. 4. 


406 A. L. Leach—Bagshot Beds, Shooters Hill, Kent. 


gradually into normal blue or brown London Clay with septarian 
nodules. In the same series of excavations (1905) a trench at the 
junction of Shrewsbury Lane with the Dover Road showed the 
Shooters Hill gravel resting irregularly on a bed of fine clean 
yellowish sand quite unlike anything previously noted in the 
numerous pits and trenches opened upon the Hill, but as unfortunately 
the trench was only a few feet deep the relation of this fine sand to 
the London Clay could not then be made out. 

From the evidence of these sections I was led to think that patches 
of Bagshot Beds still remained beneath the ‘ gravel cap’ on Shooters 
Hill, but until the present year no opportunity occurred of confirming 
this view. In July a sewer trench 12 feet deep was fortunately 
opened on the summit of the hill (424 O.D.) in the main road a few 
yards south-east of ‘‘The Bull”, and the section displayed in this 
trench afforded what seems to me quite satisfactory proof of the 
existence of Bagshot Beds in fair thickness at this point. 


Section of Bagshot Beds on Shooters Hill, Kent. a, road-metal; 4, Shooters Hill 
gravel in reddish clay ; ¢, very fine pale-buff sand; d, yellow and orange loamy 
sand; ¢, pale-brown loam and clay. Length of section, 20 feet. Vertical 
scale, +45 inch to 1 foot. 


The new section, which remained open only a few days, showed, 
beneath the road-metal, from 1 to 3 feet of red clayey gravel with 
a very irregular base, resting sharply upon a bed of very fine pale buff 
sand without a trace of pebbles. Under the centre of the road this sand 
was 5 feet thick; it passed downwards quite evenly into 3 feet of fine 
loamy sands, orange and yellow in colour, and quite without pebbles, 
and these in turn became more clayey and browner in colour and 
finally indistinguishable from ordinary brown London Clay. The 
total thickness of the leams and sands below the ‘gravel cap’ 
probably does not exceed 11 or 12 feet; the proofs of their Bagshot 
age depend on— 

1. The quite gradual passage’ from and conformable junction with 
the Lendon Clay. 

2. The fineness of material and even bedding of the loams and 
sands, which differ in these respects very markedly from the very 
coarse, pebbly, and confusedly bedded sands of the ‘ gravel cap’, and 
resemble the loams and sands of the probable Bagshots in Sheppey. 

3. The very sharp and irregularly eroded junction between these 
fine sands and the ‘gravel cap’, which rests sometimes on the London 


Dr. H. Woodward—Bronteus from Devonian, Eifel. 407 


Clay, sometimes on the Bagshots. The Bagshot Beds, equally with 
the London Clay, lie below the irregular plane of erosion which forms 
the base of the ‘ gravel cap’. 

In horizontal extent this thick patch of Bagshots may not cover 
more than a few square rods or acres at most. On the western slope 
of the hill it is certainly cut into deeply by the later gravel. In none 
of the writings of Trimmer, Goodchild, Prestwich, Spurrell, nor of 
Mr. Whitaker, who have all described the Shooters Hill sandy and 
clayey gravels from numerous old exposures, can I find any references 
to loams and sands like those described above, nor have I seen in 
many trenches and pits examined, during the last seven years, on the 
summit and slopes of the Hill any indications of other thick patches 
of similar beds. Although it therefore seems certain that the Bagshot 
Beds are confined to a small area on the very summit of the Hill, the 
interest of the patch is twofold. Firstly, it forms a link between 
the Bagshots of the main area and those at Hensbrook in Sheppey ; 
and secondly, the height of the top of the London Clay can be definitely 
stated as 412 O.D. The basement pebble-bed of the London Clay 
was exposed in 1905 at about 240 O.D. at the junction of Well Hall 
Road and the Dover Road, half a mile from the section showing the 
top, described above. It has hitherto been impossible to estimate the 
true thickness of the London Clay of Shooters Hill, since it was not 
known that the top of the deposit remained beneath the ‘ gravel cap’. 
When the easterly dip through the Shooters Hill has been found an 
accurate estimation of the true thickness will be obtainable. 


VIII.—Ow a Pyerprum or Bronrzvs FROM THE DEVONIAN OF GEROISTEIN, 
KIFEL, PRESERVED IN THE COLLECTION oF THE LATE Mr. TowNsHEND 
M. Hatt i true ArHENeUM, Barnstaple. 


By Henry Woopwarp, LL.D., F.R.S., V.P.Z.S., F.G.S. 


Mes years ago the late Mr. Townshend M. Hall, F.G.S., of Pilton, 
Barnstaple, specially devoted his energies to the geology and 
paleontology of the Devonian rocks of North Devon, and in addition 
to a set of fossils acquired from him, now in the British Museum 
(Natural History), he left a series of local fossils to the Museum in 
the Atheneum at Barnstaple. This collection has been kindly curated 
by Mr. J. G. Hamling, F.G.8., of The Close, Barnstaple, North Devon, 
who takes a deep interest in the geology of the district. Mr. Hamling 
has called my attention to an interesting specimen in this collection 
which proves to be a pygidium of Bronteus, collected by the late 
Mr. Townshend M. Hall in the Devonian rocks of Gerolstein in the 
Eifel, which country he had visited many years ago in company with 
the late Mr. John Edward Lee, F.G.S8., of Torquay. In remembrance 
of that excursion Mr. Hall had presented the counterpart of this fossil 
to Mr. J. E. Lee, and it was supposed to be in this gentleman’s 
collection, but it cannot now be found. There is, I believe, a good 
cast of the fossil in the Townshend Hall Collection in the Natural 
History Museum. 


408 Dr. H. Woodward—Bronteus from Devonian, Eifel. 


In his Devonian Fauna of the South of England the late Rev. G. F. 
Whidborne (Pal. Soc. Mon., pp. 32-42, pl. ili, 1892) describes and 
figures six English species of Bronteus, and remarks upon the difficulty 
of determining them by reason of the fact ‘‘ that with the one exception 
of B. flabellifer, Goldfuss (in Mr. Vicary’s collection), none of the 
heads and tails have occurred in contact’’. Besides this, the specimens 
are generally very imperfect, and ‘‘ except in the case of the Bohemian 
species many of the foreign ones have been described from the pygidia 
alone”’ (op. cit., pp. 32, 33). 

Although the pygidia of many species of Trilobites can hardly be 
relied upon for purposes of determination, those of the genus Bronteus, 
as pointed out by Barrande, are often extremely well marked and 
characteristic. This happens to be the case with regard to Mr. T. M. 
Hall’s specimen of a detached pygidium from Gerolstein, and I am 
encouraged, therefore, to offer a figure and description of it here. 


Fic. 1. Bronteus Halli, sp. nov. (pygidium). Lower Middle Devonian : Gerolstein, 
Eifel. The original specimen is preserved in the Townshend Hall 
Collection in the Atheneum, Barnstaple. Enlarged twice nat. size. 

Description of Mr. Townshend Hall’s specimen. (Fig. 1.) In out- 
line the broadly expanded tail-shield or pygidium is nearly 
circular, though somewhat truncated for 20mm. along its anterior 
border, where it articulated with the thorax, its extreme breadth 
being 80mm. and its length 28mm., presenting with its coalesced 
radiating ribs the appearance of an elegant fan. The surface is but 
slightly convex, with the exception of the small triangular, much 
elevated, central area on its anterior flattened border, which is, in fact, 
the distal extremity of the median axis of the trilobite, being also the 
point of articulation between the pygidium and the last free and 
movable segment of the thorax. From this triangular raised axis, 
which is 8mm. in breadth and 5mm. in length, radiate fourteen 
rounded ribs, seven on either side of the median raised ridge, this 
latter being much wider and not bifurcated; it is, indeed, a pro- 
longation of the distal end of the triangular axis. The first rib, 
which forms the latero-anterior margin of the pygidium, is strongly 
curved downwards and is broader near its centre than the six which 
follow; the others are about of equal thickness; they are all more 
slender at first, but become gradually stouter as they approach the 


Dr. H. Woodward—Bronteus from Devonian, Eifel. 409 


margin, where they terminate in short flattened strong marginal spines. 
The interspaces between the ribs form smooth sulci, narrow at the 
anterior end, where they diverge from the axis, and broader near the 
flattened margin, where they gradually die out. 

The shelly cuticle or crust of the pygidium has been lost along 
about three-fourths of its expanded margin, exposing the cast of the 
under surface of the caudal shield, which was covered by a series of 
fine, wavy, more or less parallel lines, as may also be seen upon the 
decorticated surface of the pygidium in Jd/enus, Ogygia, Asaphus, and 
some other genera. 

In the genus Bronteus the coalesced segments forming the pygidium 
are usually seven in number, but two species are recorded by Barrande 
with only six, viz. B. laticauda, Wahl., and B. hibernica, Portl., while 
one species, 6. radiatus, Munst., is said to have eight ribs in the 
tail-shield. The prolongation of the axis forming the median ridge 
to the pygidium is most commonly bifurcated! at or near the distal end. 
With very few exceptions the margin of the pygidium in the several 
species of Bronteus is smooth and destitute of spines or spinous 
prolongations along its border. 

Mr. Townshend Hall’s specimen (Fig. 1) has fifteen spines around 
the tail-shield, marking the terminations of the pleurs of the seven 
coalesced segments which compose it, the fifteenth median spine being 
a prolongation of the distal end of the axis. 


4 


Fic. 2. Bronteus thysanopeltis, Barr. Upper Silurian: Bohemia. The median 
ridge of the tail does not appear to be bifurcated ; it has forty-five 
marginal spines on the pygidium. 

, 8. Id. A detached pygidium, having thirty-three spines along its, border. 
This figure has the median ridge of the tail-shield bifurcated. 

» 4. B. speciosus, Corda. Lower Middle Devonian. With forty marginal spines 
to its pygidium. ‘This species has the median ridge bifurcated. 


1 Thirty-one species being bifurcate, and nineteen non-bifurcate. 


£10 Dr, C. Davison—British Earthquakes. . 


One Upper Silurian species (Fig. 2), B. thysanopeltis, Barr.,' has as 

many as forty-five marginal spines on its caudal shield, while another 
detached pygidium shows thirty-three spines upon its border? (Fig. 3). 
B. (Thysanopeltis) speciosus, Corda, from the Lower Middle Devonian, 
has forty marginal spines around its caudal shield* (Fig. 4), while 
another Devonian form referred to by Barrande* has about twenty-two 
spines.° 
ie may, I think, safely conclude that Mr. Townshend Hall’s 
Gerolstein specimen is quite distinct from any other Devonian form. 
It may be characterized as having seven coalesced segments in its 
caudal shield, indicated by seven marginal spines, marking the lateral 
termination of the pleure, and by a single non-bifurcate stout median 
lobe, being a prolongation of the axis of the caudal shield, and 
terminated by a similar median spine upon its margin. The 
decorticated portion of the margin of the shield shows that the 
underside was etched by numerous fine parallel wavy lines, extending 
over even the lower surface of the marginal spines. 

I propose to designate this Gerolstein form as B. Halli, after my 
late friend Townshend M. Hall, who did so much good work in the 
Devonian rocks of North Devon. 


IX.—Tase CuHaracteristics oF British EartHquakes: A SuMMARY OF 
Twenty-one Years’ Work. 


By Cuarzes Davison, S8c.D., F.G.S. 


OR a detailed study of the earthquakes of any district, an interval 
of twenty-one years is too brief. Long-period variations of 
frequency cannot be established. We can form no satisfactory 
conception of the distribution of seismic energy in space, for some 
foci may le inactive for a much longer time, while others may 
continue in operation without apparent change. But, to ascertain 
the characteristic features of the earthquakes, to investigate their 
relations with those which precede and follow them, or to trace 
their connexion with the structure of the central districts, such an 
interval is possibly of sufficient length. In any case, the defects 
resulting from its brevity may be partly compensated by uniformity 
in treatment and in the methods of investigation. 


1 J. Barrande, Systéme Silurien du Centre de la Bohéme, pt. i, vol. i, 1852, 
Texte Crustacés: Trilobites, p. 843, pl. xlvij, fig. 6. 

2 Op. cit., pl. xlvii, figs. 11, 12. 

3 Kayser’s Zext-book of Comparative Geology (translated and edited by Philip 
Lake), p. 121, fig. 5, 1893; and Girich, Leitfossilien, Taf. xlvii, fig. 1. 

* See explanation to pl. xlvii, under fig. 12. 

> Barrande writes—‘‘ Bronteus acanthopeltis (Schnur) was recently discovered in 
the Eifel by Professor Schnur, of ‘'réves. It presents the nearest analogy with 
B. thysanopeltis. It is distinguished, however, by possessing less than half the 
number of spines around the pygidium. It only came to our knowledge by the 
kindness of Professor Schnur, who was so good as to send it to us at the moment 
when our text was going to press.’? [I cannot, I regret to say, find any figure of 
this species. | 


Dr. C. Davison—British Earthquakes. 411 


The earthquakes of the last twenty-one years have been in no 
respect unusual. None has exhibited in its central area so destructive 
an intensity as the Colchester earthquake of 1884. Nor has any 
borne a train of after-shocks so numerous as that of the Comrie 
earthquake of 1839. Three earthquakes (those of Hereford in 1896, 
Inverness in 1901, and Swansea in 1906) were, however, strong 
enough to cause considerable damage to buildings; and, in the low- 
lying country on the south side of the Ochil Hills, there have been 
many slight shocks which in their nature and frequency approximate 
towards those which have made the name of Comrie famous. 

Several of the more important seismic centres in this country have 
lain dormant or nearly so during these years. Rumbling noises, 
apparently underground, are said to have been heard in West Mersea 
Island, off the coast of Essex, and, if seismic, may possibly be 
connected with the centre which gave rise to the Colchester earth- 
quake twenty-six years ago. The Comrie focus is represented by 
three slight shocks, and seems to have relapsed into that state of 
quiescence which may precede another outburst of energy. On the 
other hand, the important focus in the neighbourhood of Inverness has 
been unusually active, and other well-known foci have exhibited those 
signs of flickering vitality which from time to time interrupt the 
monotony of our geological existence. 

Hardly any part of Great Britain has been entirely free from the 
transitory effects of earthquake shocks, the only districts left 
undisturbed being the greater part of Durham and Northumberland 
and some of the southern counties of Scotland. 


FREQUENCY. 


Taking into account only those earthquakes recorded by more than 
one observer, the total number which have occurred in Great Britain 
during the interval considered is 250, the greatest numbers in any 
single year being 25 in 1890, 23 in 1901 and 1906, and 20 in 1892, 
and the least numbers being 1 in 1897 and 1899, and 2 in 1895 and 
1902. Of the total number, 50 (including two with submarine 
origins off the coasts of Cornwall) originated in England, 27 in 
Wales, and 173 in Scotland. Thus, on an average, one earthquake 
occurs in Great Britain every month. Also, out of every 20 earth- 
quakes, 4 occur in England, 2 in Wales, and 14 in Scotland; or, 
taking area into account, 2 occur in England, 7 in Wales, and 11 in 
Scotland. 


IntTEeNsITY AND DisturBED AREA. 


Of the 250 earthquakes, 3 were of intensity 8 of the Rossi- 
Forel scale, 9 of intensity 7, 7 of intensity 6, 29 of intensity 5, 64 
of intensity 4, 127 of intensity 3 or about 3, while 11 were merely 
earth-sounds unaccompanied by any perceptible tremor. In Japan, 
220 of the shocks would be described as weak, 16 as strong, and 3 as 
violent; in Italy, 127 would be considered slight, 64 moderate, 36 
strong, and 12 very strong. 


412 Dr. C. Davison—British Earthquakes. 


The connexion between the intensity of the shocks and the areas 
disturbed by them is shown in the following table :— 


Tape I. 
Disturbed Area in Square Miles. 
Intensity. 
Maximum. | Minimum. Average. 

8 98000 33000 65900 
7 63600 1000 24500 
6 3100 74 1200) wl 
5 3000 90 $50 
4 1130 28 260 
3 219 183 126 


The intensity at the epicentre is not, however, proportional to the 
energy expended in producing an earthquake, for it depends to ~ 
a great extent on the depth of the focus and the nature of the surface 
rocks. A more satisfactory though still a rough test is the area 
included within a given isoseismal, say that of intensity 4.1 If an 
earthquake be regarded as strong when this area exceeds 5000 square 
miles, as moderate when it lies between 1000 and 5000 square miles, 
and as slight when it is less than 1000 square miles, then Great 
Britain has been visited during the last twenty-one years by 9 strong, 
7 moderate, and 228 slight earthquakes, and 11 earth-sounds.? 


PERIODICITY. 


The monthly distribution of earthquakes is given in the next 
Table (II), the upper figure denoting the number of earthquakes 
during the first 14 days in February and the first 15 days in each 
of the other months, the lower figure the number ose ed during the 
remainder of each month. 


Tasie II. 


Jan. | Feb. | Mar. | Apr. | May | June | July 


Aug. Sept Oct. | Nov.| Dee. 


Applying the method of overlapping means’ to determine the annual 
and semi-annual periods, it appears that there is a well-marked 
annual period with its maximum in October, the amplitude being 


‘ The disturbed area is an unsatisfactory test, for the Pembroke earthquake of 
1893 was felt over a larger area than the stronger shock of 1892, and the Derby 
Sculie cele of 1904 than the stronger earthquake ‘of 1903. 

The strong earthquakes are those of Pembroke in 1892 and 1893, Hereford in — 
1896, Inverness in 1901, Derby in 1903 and 1904, Carnarvon in 1903, Doncaster in — 
1905, and'Swansea in 1906. ‘The moderate earthquakes are those of Bolton in 1889, 
Inverness in 1890, Leicester in 1893, Carlisle in 1901, Strontian in 1902, Derby in 
1906, and Oban in 1907. 

3 Phil. Trans., 1893 A, pp. 1108-15; Boll. della Soc. Sismol. Ital., vol. iv 
1898, pp. 89-100. 


Dr. C. Davison—British Earthquakes. 413 


‘37 of the average monthly number. The semi-annual period is less 
pronounced, and its reality is doubtful owing to the smallness of the 
amplitude, which is only ‘14. ‘he analysis gives the maximum 
epochs in the middle of May and November. 

The next Table (III) illustrates the hourly distribution of the 
earthquakes, those which are reported as occurring at the exact hours 
being divided equally between the hours before and after. 


TasuE IIT, 


As the shocks were not recorded instrumentally, it is useless 
applying the method of overlapping means to these figures. The 
variations in frequency are no doubt chiefly due to more favourable 
conditions existing at certain times of the day, as, for example, the 
early hours of the night (9 to 11) and the hour 1 to 2 a.m., when 
many persons lie awake after their first sleep. The increase of 
apparent frequency in these hours is manifest in every earthquake 
catalogue, but a feature which seems to be peculiar to British earth- 
quakes is the large number felt from 4 to 5 p.m. Of the sixteen 
earthquakes recorded during this hour, seven occurred on Sunday, 
while two others were strong shocks that could not have passed 
unnoticed at any time of the day. It is, therefore, probable that the 
number of slight shocks recorded in Great Britain would be almost 
doubled if all the hours of the day were as restful as those devoted 
to the modern institutions of the Sunday afternoon siesta and the 
5 o'clock tea. 


NATURE OF THE SHOCK. 


As a general rule, in British earthquakes the shock consists of 
a single series of vibrations, which increase rapidly in strength, until 
one or several of greater prominence are felt, after which they fade 
as rapidly away. The average duration of the shock in such cases 
is about four seconds, though, as in the Carnarvon earthquake of 1908, 
it may be as much as 6°7 seconds. In very slight earthquakes there 
are no prominent vibrations, and only a weak tremor is perceived; in 
slight earthquakes the shock often begins with a single prominent 
vibration, like the thud of a falling body, followed by a brief tremor 
as such a fall would produce in a building. In these earthquakes 
the average duration of the shock seldom exceeds two seconds and is 
often less. 

In a few earthquakes the shock consists of two parts, in each 
of which the vibrations increase to a maximum and then die away. 
The two series generally differ in intensity and duration, and 
occasionally in the period of their vibrations. As a rule, the interval 
between the two parts is one of absolute rest and quiet, but 
occasionally it is occupied by a weak tremor and sound which are 


414 Dr. CO. Davison—British Earthquakes. 


observed only near the epicentre, so that, at a distance from that 
region, the shock consists of two entirely detached parts. The 
average duration of the interval of rest is 2°7 seconds, and that of 
the whole shock about six or eight seconds, rising, as in the Hereford 
earthquake of 1896, to 9°3 seconds. It is now known‘ that, in these 
cases, the double shock is caused by impulses in two distinct foci, the 
impulses being either simultaneous or separated by an interval which 
is often less than the time taken by the earth-waves to travel from 
one focus to the other. Of the 250 earthquakes, at least eleven (or 
about 4 per cent.) belong to this class of twin earthquakes. 


SounpD-PHENOMENA. 


The sound which accompanies an earthquake is a deep rumbling 
sound, so low that it is inaudible to some persons, while to others 
in the same place it appears louder than any thunder. That the 
inaudibility is not due to inattention is clear from the fact that, in 
the Inverness earthquake of 1901 (which occurred at 1.24 a.m.), 
86 per cent. of the obseryers who were awake, and 84 per cent. of 
those who were asleep, heard the sound which preceded the shock. 
For the Doncaster earthquake of 1905 (which occurred at 1.37 a.m.) 
the corresponding figures are 93 and 91 per cent. 

Of the 250 earthquakes, 197 (or 79 per cent.) were certainly 
accompanied by sound. In 4 cases, the observers state that they 
heard no sound; in 49 cases, no reference is made to the sound- 
phenomena. Of these 53 earthquakes, 28 occurred in the Ochil 
district, 10 in Glen Garry, 11 were after-shocks of strong earthquakes, 
and 4 were slight earthquakes in various places. But all, without 
exception, were feeble tremors, the number of observers was small, 
and there can be little doubt that, with a larger number, there would 
have been some who would have heard and recorded the sound. It 
is probable, therefore, that all British earthquakes are attended by 
audible vibrations. 

In strong earthquakes the sound was heard on an average by 
83 per cent. of the observers, in moderate earthquakes by 98 per 
cent., and in slight earthquakes by 97 per cent. This difference is 
partly due to the fact that, in slight earthquakes, the sound is 
generally a much more prominent feature than the shock, and partly 
to the variable size of the sound-area. In slight earthquakes, the 
sound-area either coincides with or overlaps the disturbed area; in 
moderate earthquakes, the two areas are approximately coincident; 
in strong earthquakes, the sound-area falls short of the boundary of 
the disturbed area, the sound-area varying from 43 per cent. of the 
disturbed area in the Derby earthquake of 1904 to 82 per cent. in 
the Inverness earthquake of 1901. On an average, the sound-area 
is 64 per cent., or roughly two-thirds, of the disturbed area. 

In moderate and slight earthquakes, the percentage of audibility 
is practically uniform throughout the area affected. In strong earth- 
quakes, with a large disturbed area, the decline in audibility as the 


1 Quart, Journ. Geol. Soc., vol. lxi, 1905, pp. 18-83. 


—— ay a 


Dr. C. Davison—British Earthquakes. 415 


sound-waves recede from the centre is distinctly marked. Within 
the central isoseismal, 97 per cent. of the observers on an average 
hear the sound, and in the successive zones bounded by the isoseismals, 
the average percentages of audibility are 94, 88, 69, and 60 respectively. 
Close to the boundary of the sound-area, there is a rapid decline 
to zero. 

The sound may be classified under one of the following types: 
(1) Wagons, trains, traction-engines, etc., passing, (2) thunder, 
(3) wind or a chimney on fire, (4) loads of stones falling, (5) the fall 
of a heavy body, (6) explosions, and (7) miscellaneous sounds, such 
as the trampling of many animals, the roar of a waterfall, etc. The 
following Table (IV) shows the average frequency of reference (in 
percentages of the total number) to these different types for the three 
classes of British earthquakes. In the last two lines of the table are 
given separate figures for two divisions of slight earthquakes, the 
first division haying a long focus and the second division a short 
focus. 


Taste LY. 
Type. 
Harthquakes. 

1 2 3 t 5) 6 7 

Strong . : ; . | 46 24 10 5 3 7 5 
Moderate . : F a, 29 26 4 5 5 8 3 
Slight : c c 5 393 29 5) 7 9 14 3 
,, (long focus) . - | 40 37 + 1 4 10 4 

,, (short focus) . 5 || 29 26 6 9 11 16 3 


Omitting the seventh type, the first three may be regarded as of 
long and the next three as of short duration. The percentage of 
reference to types of short duration is 16 for strong earthquakes, 
19 for moderate earthquakes, 31 for slight earthquakes, or 16 for 
slight earthquakes with a long focus and 37 for those with a short 
focus. It will be noticed that the sounds attending strong and 
moderate earthquakes, and also slight earthquakes with a long focus, 
are approximately of the same character. 

In the neighbourhood of the epicentre, the sound varies greatly in 
character and intensity. When the shock begins, the sound becomes 
deeper and more rumbling, and with the strongest vibrations deep 
booming explosive crashes are heard by those observers who possess 
a low limit of audibility. In the zone outside the central isoseismal 
the crashes are less frequently heard, but still the sound changes 
perceptibly while the shock is felt, becoming rough and grating; 
while, near the boundary of the sound-area, it is a low monotonous 
moan like the boom of very distant thunder. Table V shows the 
variation in type in strong earthquakes, beginning with the central 
zone A, and continuing with the zones B, C, D, E, bounded by 
successive pairs of isoseismals. 


416 Dr. C. Davison—British Earthquakes. 


TABLE V. 


Thus, as the distance from the origin increases, there is a steady 
diminution in the references to types 2, 4, and 6, an increase in 
those to type 8, and on the whole an increase in those to type 1.' 
Omitting type 7, the percentage of references to the types of long 
duration (1 to 8) for successive zones are 76, 81, 86, 88, and 94, 
implying, not that the duration of the sound increases, but that 
the sound becomes smoother and more monotonous in the outer 
zones. 

Occasionally, the sound is heard before the shock and becomes 
inaudible as soon as the first vibrations are felt. With a very few 
exceptions, however, the sound, when heard at all, accompanies the 
shock, though it is heard by many observers both before and after 
the shock. The time-relations of the principal epochs of the sound 
and shock are given in Table VI, in which the figures in the columns 
headed p, e, and f denote the number of records per cent. in which 
each epoch of the sound preceded, coincided with, or followed the 
corresponding epoch of the shock; those in the columns headed g, 
e, and Z denote the number of records per cent. in which the duration 
of the sound was greater than, equal to, or less than that of the 
shock. 


Taste VI. 

eto Epoch of Relative 
Earthquakes. pee. one: Max. Int. Duration. 

aes he | 
ag Choa leeefiam||, 622 Ngee ye | c | SF ianeg, e 1 
Strong . | 66 | 25 | 9 | 15 | 40 | 45 | 22 | 68 | 10 | 68 | 27 | 5 
Moderate . . | 66 | 29) 5 | 12 | 48) 45 | 24 | 738 | 3B) 75 | 28 | 2 
Slight. - . | 59 | 84 | 7 | 14] 47 | 40 | 83 | 67 |... | 68 | 41) 2 


This table shows that there is a close resemblance, as regards 
time-relations, between all three classes of earthquakes. Roughly 
speaking, two out of every three observers who hear the sound at all 
hear the fore-sound, two out of every five hear the after-sound, while 
to two out of every three the sound is loudest at the instant when the 
shock is strongest. 


1 The slight decrease in the two outer zones is probably due to the comparative 
uniformity in the intensity of the sound at great distances. 


Dr. C. Davison—British Earthquakes. 417 


The next Table (VII) shows how slightly the time-relations of the 
sound and shock yary throughout the sound-areas of strong earth- 
quakes. 


Tasie VII. 


wee Relative 
ee Beginning. End. Dec 


OVE Oo SiS SOUR NE ON 


67 | 30 3 | 19 | 42 | 38 | 70 | 28 
69 | 24 7 | 15 | 42.) 44 | 69 | 24 
70 | 20 | 10 | 15 | 44 | 41 | 66 | 27 
63 | 25 | 12 | 21 | 44 | 36 | 54 | 38 


Dame 
wm~ Tt 


The precedence of the shock by the sound is generally attributed 
to a greater velocity of the sound. If this were the case, however, 
the sound, with increasing distance, would be more generally heard 
before the shock and less frequently after it. There is no evidence 
whatever of such a displacement of the sound in the above Table. 
The only tendency distinctly noticeable is towards equality in the 
relative duration, and this might be expected from the gradual 
quenching of the weaker vibrations which constitute the fore-sound 
and after-sound. 


Minor SHocks. 


The series of slight shocks which oecur in Great Britain belong to 
two classes, one including those which have been confined to Glen 
Garry and the Ochil district, the other those which precede and follow 
the stronger earthquakes. 

The Glen Garry series lasted for about ten years, from 1889 to 
1899. In this interval 41 slight shocks were recorded, the majority 
occurring during the three years 1890-2, when the numbers felt 
were 11, 18, and 6 respectively. The Ochil series began in the year 
1900, and is still (1910) continuing with unabated frequency. Up to 
the end of 1909, the total number recorded is 83, 4 having occurred in 
1900, 1 in 1908, 10 in 1905, 19 in 1906, 13 in 1907, 17 in 1908, and 
18 in 1909. They vary considerably in intensity. Two, namely, those 
of September 21, 1905, and October 20, 1908, were strong within the 
epicentral district, and each disturbed an area of about a thousand 
square miles. But they should be regarded as stronger shocks than 
usual, rather than as the parents of trains of after-shocks, for the 
slight shocks which followed were not more frequent immediately 
after them than at other times. 

True accessory shocks are almost confined to the strong earthquakes 
which disturb areas of more than 5000 square miles. The total 
number of such shocks is 71, all but five of which attended the strong 
earthquakes and the Inverness earthquake of 1890, and of the majority 
15 were fore-shocks and 51 after-shocks. It is worthy of notice that, 
as regards after-shocks, there is a marked difference between simple 
and twin earthquakes. The three simple earthquakes of Inverness in 

DECADE V.—VOL. VII.—NO. IX. 27 


418 Dr. C. Davison— British Earthquakes. 


1890 and 1901 and Carnarvon in 1903 were followed by 38 after- 
shocks, and the seven strong twin earthquakes by 18 after-shocks. 


DisTRIBUTION IN SPACE. 


The total number of earthquakes which it is possible to associate 
with known lines of fault or folding is 199.1. Of the 199 earthquakes, 
153 were probably connected with faults of the Caledonian system, 
23 with Charnian, 10 with Malvernian, and 13 with Armorican faults. 
In Scotland, with the exception of the Loch Broom earthquake of 
1892, which was connected with a Charnian fault, the remaining 
129 shocks were due to movements along Caledonian faults. In 
England 15 earthquakes were connected with Caledonian faults, 22 
with Charnian, 6 with Malvernian, and 5 with Armorican faults. In 
north-west and central Wales, the earthquakes were connected with 
Caledonian faults, in the south of Wales with Armorican faults. Of 
the nine strong earthquakes, the Inverness earthquake of 1901, the 
Derby earthquakes of 1903 and 1904, the Carnarvon earthquake of 
1903, and the Doncaster earthquake of 1905 were connected with 
Caledonian faults, the Hereford earthquake of 1896 with a Charnian 
fault, and the Pembroke earthquakes of 1892 and 1898 and the 
Swansea earthquake of 1906 with Armorican faults. The last four 
earthquakes were the strongest felt in this country throughout the 
twenty-one years. Twin earthquakes are entirely confined to England 
and the south of Wales. 


OrtciIn oF British EaARTHQUAKES. 


The study of British earthquakes has led to the association of 
a large number of them with known faults, especially in those in 
which there is reason to think that the foci were situated at a small 
depth. In other cases, the investigation of the earthquakes has 
thrown light on the structure of the epicentral districts at depths far 
beyond the reach of methods at the disposal of the field-geologist. 
For instance, the complicated structure of the English Lake District 
is superposed on one of a more simple character, the Carlisle earth- 
quakes of 1901 having originated in a fault not less than 23 miles 


in length, and directed approximately N. 5° E. Similarly, in south” 


Glamorgan, as shown by the Swansea earthquake of 1906, a fault at 
least 223 miles long runs in a direction about E. 5° N. from west of 
Swansea to the neighbourhood of Llwynpia. 

A rough approximation to the length of the seismic focus is given 
by the difference in length between the longer and shorter axes of 
the innermost isoseismal.? In estimating the average length of the 
focus for the different classes of British earthquakes, after-shocks are 
omitted, as in them the length of the focus is governed to some extent 
by that of the principal earthquake. The results are as follows :— 


1 The earthquakes omitted are the 41 shocks felt in Glen Garry from 1889 to 1899, 
2 shocks near Tadcaster in 1890, 5 in Pembrokeshire in 1893, 3 m Annandale in 
1894 and 1896, and 1 near Beddgelert in 1904. 

2 Gerland’s Beitrage zur Geophysik, vol. ix, 1908, p. 224. 


Notices of Memoirs—Dr. M. Manson on Gilaciations. 419 


Taste VIII. 
Barchoualees Mean length of focus 
ee gee 4 in miles. 
Strong ‘ : 124 
Moderate. a5 13 
Slight,a@ . A 12 
ee : | 4} 


Slight earthquakes are obviously divisible into two sub-classes, the 
first in which the focus is 9 miles or more in length, the second 
in which the focus is 6 miles or less in length.! The above Table 
gives the reason why the sound should be of nearly the same 
character in strong, moderate, and the first division of slight earth- 
quakes. Thus, the intensity of all but the slightest earthquakes 
depends, not on the magnitude of the focus, so much as on the amount 
of relative displacement along the surface of the fault. 

British earthquakes, according to the nature of the shock, are 
divisible into two classes, simple and twin, and this classification 
corresponds to a difference in origin. Simple earthquakes are due to 
continuous slips, as a rule along strike faults; twin earthquakes are 
caused by rotation of the median limb of a crust-fold along a transverse 
fault, the two foci coinciding with the crest and trough of the fold, 
the interfocal region with the practically undisplaced portion of the 
median limb about which the rotation takes place. In this connexion, 
it is worthy of notice that the average distance between the epicentres 
of British twin earthquakes is 10 or 11 miles, which agrees closely 
with the average distance of 9 to 12 miles between the crests of the 
great crust-folds in France. 

The average length of the focus in twin earthquakes is about 12 miles. 
Thus, the average length of focus in twin earthquakes and in other 
earthquakes, whether strong or moderate or, in certain cases, slight, 
is nearly the same, and is probably equal to, or it may be slightly 
more than, the average distance between the crests of the crust-folds. 
In other words, the magnitude of the crust-folds seems to determine 
the length of fault-slips along strike faults as well as along transverse 
faults. 


NOTICES OF MEMOTRS. 


—————— 


1.—Tue Srenrricance or Harty AND OF PLEISTOCENE GULACIATIONS.? 
By Marsprn Manson, Ph.D. 


fY\HE objects of this paper are to point out the significant differences 
between the preceding, accompanying, and succeeding phenomena 
of early glaciations and the corresponding phenomena of Pleistocene 


1 In determining the average for the second sub-class, a large number of very 
slight shocks were unayoidably omitted ; their inélusion would, of course, lower the 
average considerably. 

* Being an abstract of a paper read before the Eleventh Session of the Int. Geol. 
Congress, Stockholm, August, 1910. 


420 Notices of Memoirs—Dr. M. Manson on Gilaciations. 


and present glaciation. One of the broadest and most recent sum- 
maries on the subject is that of Professor T. W. Edgeworth David, 
F.R.S.1 He finds that in the following horizons the presence of 
evidences of extensive ice-action is quite firmly established :—Lower 
Cambrian, Devonian, Permo-Carboniferous, Pleistocene. 

Professor A. P. Coleman also reviews the whole subject very clearly, 
and finds four periods of extensive glaciations—(1) Lower Huronian, 
left its effects over hundreds of thousands of square miles ;* (2) Early 
Cambrian, in widely separated regions; (3) Permo-Carboniferous, for 
large parts of the world; (4) Pleistocene, very general. We there- 
fore accept, for the purposes of this discussion, that ice-action of great 
extent occurred in these periods. 

Cambrian Glacial Action—KEvidences of the action of ice in 
Cambrian time have been observed from Arctic, through north 
temperate and tropical, and in south tropical latitudes. Evidences 
of Cambrian life have been found which are of wide distribution as 
to latitudes and indicative of warm seas. ‘‘The testimony of the 
fossils, wherever gathered, implies nearly uniform climatic conditions, 
not only over our own continent, but throughout all the earth where 
records of the Cambrian Period are found.’’? The extremely wide 
range of life in Cambrian time justified Dana in saying, ‘‘ There was 
no frigid zone, and there may have been no excessively torrid zone.”’ + 

Ewidences of Glacial Action in the Devonian Era.—When the 
evidences of glacial action in the Devonian era are compared it 
is found that they embrace nearly as wide a distribution in latitude 
as do the evidences of the life of that era, and that, lke the 
distribution of temperature and of life in the preceding Silurian 
and succeeding Carboniferous era, both life and glacial action were 
distinctly non-zonal in distribution, and the former indicated warm 
temperate or tropical conditions. 

Permo- Carboniferous Ice-sheets—During Permo-Carboniferous time 
extensive sheets of ice were laid down in the tropical latitudes of 
both hemispheres. During this period the life was indicative of 
temperate conditions rather than Arctic, and its distribution was 
worldwide. ‘‘The Permian Period lies in the midst of geological 
history, with periods of great uniformity and remarkable Polar 
geniality both before and after it.” ° 

It must be recognized at once that zones of temperature did not 
prevail immediately before, during, nor immediately after the Permo- 
Carboniferous glaciation ; that whatever part solar radiation played in 
the climatic distribution of that age it was not the controlling part, as 
at present, and that to attempt to fit such a distribution of temperature 
to solar radiation involves suppositions and hypotheses which have not 
been made to harmonize with present conceptions of solar-controlled 
climates. The volcanic heat liberated at the close of this era, and that 


1 See Trans. Tenth Int. Geol. Cong., Mexico, vol. i, pp. 437-82, 1906. 

2 Bull. Geol. Soc. Am., vol. xix, pp. 847-69, November, 1908. See also Davis, 
ibid., vol. xvii, p. 414, August, 1906. 

8 Chamberlin & Salisbury, Geology, ii, p. 273. 

4 Manual, 4th ed., p. 484. 

5 Chamberlin & Salisbury, ii, p. 656. 


ee 


Notices of Memoirs—Dr. M. Manson on Glaciations. 421 


slowly brought into effect from cooling lava and radio-active substances 
by subsequent denudation, would tend to raise the temperature of the 
air, from which it could escape only by slow processes’ under the 
powerful conservative influences of solar radiation. The widespread 
geniality of the succeeding period may be, in part at least, attributed 
to this accession of heat—the geniality compared with that of the 
preceding period, when tropical life flourished at all latitudes. Taking 
the three epochs in succession, Carboniferous, Permian, and Triassic, 
it appears that the Permian was a period of marked temperature 
depression in a series of non-zonal climates.’ 

Pleistocene Glaciation and Conditions.—Pleistocene glaciation followed 
a period during which cold temperate forms of life were for the first 
time distinctly developed over wide ranges of latitude, which, during 
the immediately preceding period, were occupied by temperate forms. 
For the first time also marine life of Arctic habit took possession of 
oceans previously supporting more temperate forms only. The cold 
became so general as to be ‘ worldwide’ in its effects. 

A Review and Comparison of these Glaciations and of Life-—When 
the distribution in latitude of the evidences of early glaciations and of 
life are compared with Pleistocene glaciations and the distributions of 
modern life, it is observed— 

1. That both early and late glaciations and all life prior to the 
modern era were distributed over extreme ranges of latitude and 
apparently without regard to exposure to solar radiation. 

Pleistocene glaciation may have reached its maxima progressively at 
different latitudes, that is, whatever may have been the maximum 
extension of glaciation in the latitude of the tropics, this maximum 
was apparently reached prior to the maximum in, say, latitudes 45 to 
55 degrees; similarly, glacial maxima in these latitudes may have 
preceded maximum glaciations in Polar latitudes. But taken as 
a whole, Pleistocene glaciations were not laid down in accordance with 
present zonally distributed climates. 

2. That early glaciations were preceded, accompanied, and followed 
by a widespread distribution of tropical and temperate forms of life 
and by warm oceans, while Pleistocene glaciation was ‘ phenomenal’, 
was preceded by a period of widespread cold temperate life, and 
accompanied by colder oceans than had previously prevailed. 

3. That the earlier glaciations were followed by periods of wide- 
spread tropical or temperate life, while Pleistocene glaciation was 
followed by a period in which life and temperatures were restricted 
to zones distinctly dependent upon solar radiation for their establish- 
ment and maintenance. 

A deduction which seems fully justified is that up to the culmination 
of Pleistocene glaciation zones of temperature were scarcely perceptible, 
if at all, which deduction is confirmed by both the wide distributions 
of life and the evidences of glacial action in low latitudes in the pre- 
Pleistocene eras. 

The absence of distinct zones of climate is highly significant, and 

' Chamberlin & Salisbury, ii, p. 672. 

2 Neumayr held that there were climatic zones in Jurassic and Cretaceous times ; 
see W. T. Blanford, Address to Geol. Soc., 1890, p. 55.—Ep. Grou. Mac. 


422 Notices of Memoirs—Dr. MW. Manson on Gilaciations. 


clearly established the fact that a solar control of climates similar 
to that at present existing did not prevail prior to the modern era,! 
or that some factor was active which did not admit of the zonally 
distributed climates of solar control. 

The distribution of ice and of fossil life during Huronian, Cambrian, 
and Permo-Carboniferous time, and during preceding and succeeding 
eras to the close of Pleistocene time, are so widely at variance with 
a solar-controlled distribution of temperatures like the present that it 
seems impossible to assign these phenomena merely to variations in 
solar radiation. Under solar control, for instance, what would become 
of Polar and mid-latitude life while tropical latitudes were glaciated 
nearly or quite to sea-level ? 

The phenomena of geological and present climates may be interpreted 
under the hypothesis that prior to the Recent or Human Epoch the 
earth was more continuously clouded, and thereby deprived of the 
zonal temperature control of solar radiation.’ 

When these evidences of ice-action and the phenomena of life are 
broadly compared, under this hypothesis, it appears to the writer— 
(1) That accordingly ice-fields were laid down generally without 
regard to latitude, although Pleistocene glaciation reached its maximum 
along the broadest land areas under the north temperate rain-belt, 
and this maximum may have been reached after the inauguration 
of solar control in tropical latitudes. (2) That the earlier glaciations 
were contemporaneous with tropical and temperate land and marine 
forms, and that the greater exposure of the continents to loss of heat, 
and their low specific heat and conductivity, caused them to cool more 
readily, thus frequently forcing land animals to seek warmer conditions 
in the oceans, and from these permanently marine forms of life haye 
descended. (8) That Pleistocene glaciation followed an extremely 
gradual although fluctuating refrigeration of the earth as a whole 
when its crustal condition became more stable than ever before and its 
oceans for the first time fully and completely chilled, and that the 
stress of cold was so general that the oceans did not then offer more 
congenial conditions to even the cold temperate land life of the 
immediately preceding period; that this stress was first relieved in 
regions of least cloudiness by the penetration of solar radiation to the 
surface, and that more moderate conditions spread thence into the 
solar-controlled, zonally distributed temperatures of to-day; that the 
accession of heat through continuous exposure and the trapping of 
solar radiation, converted into long wave-length rays, is a cumulative 
process which has recorded and is yet recording its gradual but 
irregular progressiveness by the removal of Pleistocene glacial 
conditions and the corresponding advance of life. (4) That only 
after the culmination of this marked and phenomenal glaciation did 
temperatures and life pass from a non-zonal to a zonal distribution, 
which manifests itself in zones of life and of climates, and marks 


1 There is an apparently zonal distribution of the very much mixed groups of 
Pliocene life which may have resulted from a similar distribution of temperatures, 
but exceptional conditions warn us against too implicit an acceptance of this conclusion. 

2 See Trans. Tenth Int. Geol. Cong., Mexico, vol. i, pp. 849-405, 1906. 


i. i sl 


Notices of Memoirs—Dr, M. Manson on Glaciations. 423 


Pleistocene time as the most significant transition epoch of the climatic 
history of the earth. 

There seems to be a tendency in recent years to fall back upon the 
hypothesis of variations in the emissive power of the sun to account 
for the variations of surface temperatures indicated by ice formations.* 

It is certainly quite possible and even probable that the sun’s 
emission has altered within geological time, but neither the distribu- 
tion of fossil life nor the evidences of ice formations occur with that 
zonal arrangement in harmony with solar-controlled climates, so that 
to the writer it seems necessary to attribute geological climates to 
a uniformly distributed source of heat, and to eliminate solar control 
by the reasonable assumption of persistent cloudiness. It is not 
implied that the clouds were so thick as to prevent the transmission 
of light such as is now received on overcast days, but a far less thick 
layer than that would suffice to screen off most of the solar-heating 
effects. Moreover, under the hypothesis that solar radiation was 
interrupted by a thin but continuous stratum of cloud, there is no 
reason why glaciers should not flow into the sea at any latitude. 

When cloud densities decreased to approximately present conditions 
the tropical zones of downcast currents and minimum cloudiness were 
the regions first affected, and in these solar radiation first reached the 
surface. ‘hus solar radiation which, with a continuonsly cloudy sky, 
fixed the tropical zones as regions most exposed to cold downcast 
currents and to glaciation, also fixes them, with present cloudiness of 
52 per cent. of the earth’s surface, as regions of maximum exposure 
to solar radiation. The great continental glaciers of the northern 
hemisphere were grouped about the North Polar region for the reason 
that continents are so grouped, and for the additional reason that 
atmospheric circulation fixes latitude 50° N. as one of the belts of 
maximum storm circulation and precipitation. 

Solar climatic control distinctly manifests itself by a zonal arrange- 
ment of temperatures and of life; under this control the disappearance 
of Pleistocene ice-sheets is taking place. ‘The earth is therefore not 
in an era of senility or decrepitude, but in the springtime of a new 
life in which nobler, higher types of life are being developed. 

The difficulties attendant upon the previous explanation of climatic 
phenomena appear to the author to be due to false premises, namely, 
(1) that solar radiation controlled the climates of Pleistocene and 
previous eras; and (2) that effective earth heat, under the extremely 
slow processes of loss and bringing into effectiveness and the powerful 
processes of conservation, was entirely lost prior to the era of zonally 
disposed climates. Upon a rejection of these assumed premises we 
may freely admit that ice has been a geologic agent from the earliest 
ages, particularly upon land masses of low specific heat and extremely 
low conductivity, and that the regions of cold downcast currents were, 
prior to the Pleistocene, most exposed to cold downcast currents and 
to consequent local glaciation; and that as the supply of earth heat 
fluctuated, ice formed under favourable conditions over large geographic 
areas in any latitude and during many eras, to disappear from an 


1 Professor David, Trans, Tenth Int. Geol. Cong., Mexico, vol. i, pp. 481-2, 1906. 


424 Notices of Memoirs—C. & HE. Reid—Bovey Tracey Lignites. 


increase of available earth heat or a lowering of elevation. These 
earlier ice formations were, however, not accompanied by cold seas, nor 
upon their disappearance were zonally distributed climates established. 

The approaching, culminating, and succeeding phenomena of the 
Ice Age were therefore far more remarkable and significant than the 
corresponding phenomena accompanying the occurrences of ice as 
a geologic agent in the earlier ages. The worldwide distribution of 
cold temperate life just preceding the equally worldwide phenomena 
of Pleistocene glaciation, and the succeeding era of zonally distributed 
temperatures and life distinctly dominated by solar control, mark 
a profound change in the climatic history of the earth, and make it 
manifest that but once have the oceans chilled to that degree of cold 
which warrants the use of the term Ice Age. 

Summary.—The phenomena of the earlier glaciations and the pre- 
ceding, accompanying, and succeeding distributions of temperatures and 
of life appear to warrant the conclusions—(1) That these phenomena 
did not occur during eras of solar climatic control; (2) that there were 
apparently marked fluctuations in the amounts of available earth heat; 
(3) that during periods of deficiency and upon elevated areas, and 
particularly in zones of downcast atmospheric currents, local glaciers 
of great extent formed; (4) that these glaciations disappeared or 
varied from one of several causes, (@) accessions of heat from the 
crust, (2) variations in the elevation of the crust, (¢) possible inter- 
mittent thinnings of the denser cloud formation of earlier eras in the 
regions of minimum cloud formation, permitting solar radiation to 
reach the earth’s surface in these latitudes; (5) that these glaciations 
were not of the same order of magnitude nor did they mark the 
climacteric era of the evolution of climates as did the Ice Age. 


II.—Royat Soctery.—Tue Lienrre or Bovey Tracey. By Crement 
Rew, F.R.S., and Exzanor M. Rerp, B.Sc. Read June 16, 1910. 


N 1863 Heer and Pengelly published in the Phil. Trans. an account 
of these lignite beds and their flora. Heer classed the lignite as 
Lower Miocene, considering it equivalent to the Aquitanian of France 
and to the Hamstead Beds of the Isle of Wight. These latter are now 
referred to the Middle Oligocene. 

A statement by Starkie Gardner, that Heer’s Bovey plants are the 
same as those found in the Bournemouth Beds (Middle Eocene), has 
caused the Bovey Beds to be classed as Eocene in recent textbooks 
and on recent maps of the Geological Survey, leaving a great gap in 
the geological record in Britain. Our researches have not supported 
this view, but tend to show that Heer was right, the Bovey lignite 
being highest Oligocene, or perhaps lowest Miocene. We could find 
in the Bournemouth collection nothing to support Gardner’s view, and 
he does not appear to have collected at Bovey, his comments referring 
to the collection now in the Museum of Practical Geology. 

We therefore made a collection in the Bovey deposits, as far as the 
state of the lignite pit would allow, in order to settle if possible the 
true age. The results were unexpected, for by using new methods 
we obtained a considerable number of species, mainly identical with 


Notices of Memoirs—Dr. O. Gordou—On the Dolomites. 425 


well-known plants of the lignite of the Wetterau, which is generally 
classed as Upper Oligocene. In certain cases better specimens showed 
also that Heer’s supposed peculiar species of Bovey belong to well- 
known forms of the Rhine lignite—his Vitis britannica, for instance, 
being only a crushed seed of Vitis teutonica. Several curious new 
species were discovered, including the earliest known fudbus, a 
peculiar Potamogeton, and a new genus of Boraginee. 

A study of the cone and leaf of Sequoia couttsie proves that it is 
a true Sequoia, and not a species of Arthrotaxis. 


Il].—EpinsureH Gerotocicat Society. 


A GEOLOGICAL work by Dr. Ogilvie Gordon, entitled Zhe 

Thrust-masses in the Western District of the Dolomites in South 
Tyrol, has just been published by the Edinburgh Geological Society in 
a Special Part of their Zransactions, vol. 1x; price 7s. The text 
extends to 91 pages, and is illustrated by 2 geological maps, 
18 coloured geological sections, and a number of original photographs 
and sketches. Mrs. Gordon describes a series of gigantic thrust-masses 
composed, in that district, of Permian, Triassic, Jurassic, and Cretaceous 
rocks that have travelled from east to west above the older crystalline 
rocks of the Central Alps, and have subsequently been downthrown 
along with the older rocks and suffered further deformation in the 
region of the Dolomites. The base of the series is composed of 
brecciated rock-material belonging to the floor over which the 
subjacent mass has passed and to the lower layers of the subjacent 
mass. The lower layers of each mass differ from place to place, 
as they were masses that had been already plicated in east and west 
direction, and in the course of the overthrust movements new 
plicational forms were superinduced both in north and south and 
in east and west directions. Similarly the cross-faults intersect, or 
coalesce with, the E._W., E.N.E.-W.S.W., and W.N.W.-E.S.E. 
faults, and form fault-networks which completely isolate the adjacent 
areas in the crust. The chief Dolomite mountains, such as the 
Langkofi and Plattkofl Massive and Sella Massive, are areas of inthrow 
surrounded by faults, within which the higher thrust-slices have been 
preserved. 

One of the geological maps shows four successive thrust-masses— 
(1) a basal thrust-mass mainly composed of the Permian Quartz 
Porphyry and Gréden Sandstones, the Lower Trias, and the Caleareous 
facies of Muschelkalk and Marmolata Limestone; (2) a thrust-mass 
comprising fragments of the older strata and widely extended exposures 
of the porphyritic lavas and tufaceous and dolomite facies of Middle 
Trias; (8) a thrust-mass belonging to the same facies as (2), but 
mainly composed of Schlern Dolomite, with varying thicknesses of the 
lavas and tuffs below it and of Upper Trias and younger horizons 
above it; (4) a thrust-mass mainly composed of Upper Triassic 
Dolomite associated with infolds of younger Mesozoic strata. The 
other geological map shows the detailed stratigraphy of the Langkofl 
and Plattkofl Massive. This mountain has been regarded as a ‘ Coral- 
Reef’ of Middle Triassic age, but the supposed ‘reef’ peculiarities are 


426 Reviews—Sub- Antarctic Islands. 


interpreted by Mrs. Gordon upon the basis of the overthrust structures 
typical of the whole area. The outstanding deformational feature of 
all the thrust-slices is the rapid variation in the thickness of the 
various horizons of strata. Other features are the brecciated or 
nodular structure of the rock-material in the crush-zones, passing into 
gneissose and schistose structure, and the close cleavage penetrating 
the rocks in intersecting directions. The outward dip of the strata 
noticeable in the chief mountain-massiyes is a dip participated in 
by the subjacent thrust-masses and associated with steep flexures 
towards leading faults of the later period of downthrowing and 
horizontal displacements. Mrs. Gordon interprets the leading strike 
in the district as a curve round the north, west, and south, and the 
transversal directions as N.N.W.-S.8.E., N.-S., and N.N.E.-8.8.W.., 
the system being essentially an interference system produced in virtue 
of the coalescence of plicational effects during the interaction of north- 
south and east-west pressures. 


REVIEWS. 


——— 


I.—Tue Svus-Antarcric Istanps or New Zearanp. 
REpPoRTs ON THE GEOPHYsSIcs, GEOLOGY, ZooLtocy, AND Borany or THE ISLANDS 
LYING TO THE souTH or New Zeatanp. Edited by Professor CHARLES 
Cuitton, M.A., D.Sc., F.L.S. Published by the Philosophical Institute of 
Canterbury. 2 vols. 4to; pp. xxxv, 848. Wellington, N.Z. London: 
Dulau & Co., 1909. 
fJ\HE observations recorded in these two volumes are the results of 
an expedition made in November, 1907, with the co-operation of 
the New Zealand Government, to the more important islands that lie 
to the south of New Zealand. 

The geology of Campbell Island and the Snares is described by 
Professor P. Marshall and Mr. R. Browne, and that of the Auckland, 
Bounty, and Antipodes Islands by Mr. Robert Speight and Mr, A. M. 
Finlayson. 

In Campbell Island the oldest rock formation is a mass of gabbro, 
Somewhat larger areas are occupied by oceanic limestone, with fora- 
minifera, occasional grains of glauconite, some flints, but no detritus : 
it is regarded as probably of Miocene age. The main mass of the 
island is formed of volcanic breccias and lavas (trachyte, phonolite, 
and basalt), the terraced features being due to the outcrop of nearly 
horizontal flows of lava, separated by less resistant scoria beds. 
Abundant evidence of glaciation was observed, but the formation of 
glaciers on the island is regarded as the result of a general cause of 
refrigeration and not as specially due to elevation. The absence 
of raised beaches and rock-shelves indicates that there has been no 
recent elevation, but it seems probable that a movement of depression 
is In progress. 

The Auckland Islands exhibit evidence of ‘‘a moderately severe 
glaciation’, and there are indications that it was probably more 
intense at an earlier date. Considerable elevation of the land must 
have occurred during those times, but the upheaval is not regarded as 


Reviews— Geological Survey of Great Britain. 427 


haying been a predominating factor in the glacial conditions. Never- 
theless it is regarded as ‘‘ reasonable that the Auckland Islands were 
at least 7000 feet high”. The land now attains an elevation in places 
of more than 2000 feet, so that the uprise would have been 5000 feet 
or more, and would ‘“‘ go far to explain the connexion of New Zealand 
with a former antarctic continent”’. The main island of Auckland 
is mostly formed of basalt of middle or late Tertiary age. An older 
basic series, also conglomerate, which may represent an ancient river- 
bed, and trachytes, occupy smaller areas. Over more limited tracts 
there are exposures of granite and gabbro, the actual and relative ages 
of which are undetermined. 

The rocky islands and islets of Snares and Bounty are formed of 
granite. Of the Bounty Islands it is remarked that ‘‘The rocks near 
sea-level are worn smooth not only by the action of the breakers, but 
also by the polishing action of the feet of the seals and millions of 
penguins and other sea birds, which make the island their breeding- 
place. The general rock-surface is as slippery as glass, and exceedingly 
difficult for man to travel over. Immense quantities of guano are 
deposited on the islands during the breeding season, but during winter 
storms it is swept off, with the exception of that which accumulates 
between the boulders ’’. 

Campbell Island and the Snares are much covered with peat, and 
there is a separate article on the soils and soil-formers, by Mr. B. C. 
Aston. 

The main features of the islands are represented in a number of 
photographic illustrations and maps, and the rocks are illustrated by 
micro-sections. The entire work may be regarded as a substantial 
contribution to our knowledge of the natural history of these sub- 
Antarctic islands, with full references to the work of previous 
observers. 


IJ.—Scummary or Procress oF THE GroLogicat SurvEY oF GReEAT 
Briratn anp THE Mosrum oF Pracrican GxoLtoey For 1909. 
pp. iv, 92, with 5 text-illustrations. London: printed for H.M. 
Stationery Office, 1910. Price ls. London, W.C.: I’. Fisher Unwin. 

fY\HE important announcement is made by the Director, Dr. J. J. H. 

Teall, that the Survey of the South Wales Coal-field and that of 

the Derbyshire and Nottinghamshire Coal-field, on the 6-inch scale, 
have been completed, the work in the latter case having been con- 
nected with that carried out many years ago in the Yorkshire Coal-field 
by A. H. Green and colleagues. We learn also that the 6-inch field- 
work in Cornwall and Devon has been completed so far as at present 
contemplated. It is to be noted with regret that the name of the 
Director does not appear in the Summary; it was omitted also in the 
Summary for 1908. Such an omission is opposed to the prevalent 
notion that a man is responsible for the work he undertakes, and it is 
likely to give considerable trouble in the future to biographers and 
bibliographers. The policy of the Board of Education in omitting the 
names of the chief officers who contribute reports of the work of their 
departments to the General Report of the Board, is again a very 
inconvenient and unjustifiable piece of ‘‘ red tape’’. 


428 Reviews—Greology in the Field. 


In Scotland the mapping of Ben Nevis has led to the conclusion 
that the volcanic rocks which form the higher part of the mountain 
are of Lower Old Red Sandstone age, and that they rest on Highland 
schists which are almost entirely concealed by bordering granites. 
The structure of this region forms the subject of a separate article by 
Mr. H. B. Maufe. 

A short but important article is contributed by Mr. C. T. Clough on 
the stratigraphical relations between the Red Barren Measures and the 
Productive Coal-measures of Scotland. He states that there is no 
evidence of any break of importance between these divisions, and that 
consequently wherever the Upper Red Carboniferous strata occur, the 
Productive Measures may be expected beneath them. Mr. C. B. 
Crampton describes a Manganese deposit near Freswick, Caithness ; 
Dr. W. Gibson gives an account of three borings in the Ingleton 
Coal-field ; and Mr. John Pringle gives further particulars of a boring 
at Stowell, Somerset, that was carried through the Fullers Earth into 
the Sands beneath the Inferior Oolite. It is a remarkable fact that 
25,000 gallons of water a day were obtained from the Fullers Earth 
Rock, and that the lower strata yielded no supply. Lists of fossils 
are given from the Inferior Oolite Series. 

In the accounts of the progress of the field-work in the different 
districts of England, Wales, and Scotland there are records of many 
interesting observations on most of the geological formations from the 
Ordovician to the Lias, on Tertiary including the Bovey Beds, on 
Pleistocene and Recent deposits, as well as on the Highland schists, 
on certain supposed pre-Cambrian rocks (the Johnston Series) in 
Pembrokeshire, and on various igneous rocks. Analyses are given of 
clays from the Bovey Basin and from the Marland Clay Works, 
Torrington. 


III.—Grotocy in THE Fretp. The Jubilee Volume of the Geologists’ 
Association (1858-1908). Edited by H. W. Moncxton and R. 8. 
Herrizs. Part IV. pp. 661-898, with 14 plates. London: 
Edward Stanford, 1910. Price ds. net. 


\ ITH the exception of a general and copious index which ‘ will 
be ready shortly’, the elaborate Jubilee Volume is now 
complete. 

The present number opens with an article on ‘‘ Northumberland 
and Durham”, by Professor E. J. Garwood. After remarking on the 
scenery and tectonic features, the author gives a brief account of the 
Silurian, which is not known to include strata higher than the Wenlock 
Series. The unconformable Lower Old Red Sandstone with its andesitie 
lavas is next described, together with the intrusive rocks (granite and 
porphyrite) which indicate later phases of igneous activity. Upper 
Old Red Sandstone is doubtfully recognized in certain conglomerates 
at Windy Gyle, as the strata have been regarded by some geologists 
as basement Carboniferous. The various divisions of the Carboniferous 
and the paleontological horizons are duly described; and the author 
draws attention to the occurrence, apparently near the base of the 


a 


Reviews—Geology in the Field. 429 


Yoredale Series, of Postdonomya Becher’, which is characteristic else- 
where of the Pendleside Group. The Permian beds are then dealt 
with, and it is noted that the Magnesian Limestone is succeeded 
conformably by ‘Triassic red sandstones and marls—beds which, 
curiously enough, have been regarded as Keuper by some authorities. 
The important sills and dykes of post-Carboniferous date and the 
Glacial and newer deposits finally receive attention. 

The second article is on ‘‘ The Malvern and Abberley Hills, and the 
Ledbury District’, by Professor T. T. Groom, who gives a summary 
of his detailed researches on the tectonic structure of the region, 
together with concise accounts of the Archean and the fossiliferous 
Cambrian, Ordovician, and Silurian rocks. Special attention is given 
to the subdivisions of the Silurian, and a valuable list of fossils, showing 
the range of the species from the May Hill Sandstone to the Upper 
Ludlow, is appended. 

‘‘ Shropshire” forms the subject of the third article, and is happily 
dealt with by Professor Lapworth. Brief accounts are given of the 
several types of pre-Cambrian rocks, the Rushton schists, the 
granitic and gneissose rocks, the Uriconian, and Longmyndian. It is 
remarked that the term Uriconian has been applied to certain dis- 
connected groups of ashes and lavas, and in a table showing the 
apparent descending sequence of the lithological groups in Uriconian 
and Longmyndian the author has been led to place at the top the 
Linley volcanic series, equivalent to the Western Uriconian of 
Callaway, and at the base the Cardington volcanic series or Eastern 
Uriconian of Callaway. The intermediate groups of Western and 
Eastern Longmyndian are ranged under eight subdivisions. This 
classification, based on Professor Lapworth’s detailed field-researches, 
will be of immense service to future workers. The Cambrian rocks 
are briefly described, and the various local divisions established by 
the author in the Ordovician system again give information of special 
importance. Then follow accounts of the Silurian divisions, and 
brief descriptions of Carboniferous and newer formations, of tectonic 
geology and physiography. 

The fourth article, on ‘‘ Charnwood Forest”’, is naturally written by 
Professor W. W. Watts, whose elucidation of the complex structure 
and of the nature of the buried mountain mass has been a great 
achievement. Preserved beneath a cover of Keuper Marl, the erosion 
of this newer deposit has revealed portions of what the author terms 
“the fossil Triassic landscape of Charnwood’’. 

In the fifth article Mr. W. G. Fearnsides gives an account of the 
main features in the geology of ‘‘ North and Central Wales”. Rocks 
from pre-Cambrian to the Old Red Sandstone, sedimentary, volcanic, 
and intrusive, are duly described, attention being given to the 
prominent and characteristic fossils and to the method of formation 
of the strata. It is noted that the Old Red Sandstone is locally 
continuous in all respects with the Downtonian. The author then 
discusses the general structure of the area and the various great earth- 
movements that have taken place, and in a series of diagrammatic 
sections he illustrates his views on the more important stages in the 
building of Wales from the Uriconian era to the present day. 


430 Reviews— Yorkshire Type Ammonites. 


In the sixth article, by Dr. A. Strahan, ‘‘South Wales” is dealt 
with, mainly so far as the region has been visited by the Geologists’ 
Association. Thus the oldest rocks described are the Silurian near 
Cardiff and in Gower. Attention is directed mainly to the Old Red 
Sandstone and Carboniferous rocks, the Trias and Lias, the Raised 
Beach and Caves of Gower, and the Glacial and post-Glacial deposits, 
concerning all of which is given a summary of the latest information, 
much of it acquired by the author during the progress of the 
geological survey. The intimate connexion between the Rheetic 
beds and underlying Keuper Marls, manifest from the stratigraphic 
and paleontological evidence noted by the author, is not, however, 
recognized by him, and his views differ from those of other writers in 
the Jubilee Volume (pp. 332, 491, and 863). In a final section on 
Physiography the author discusses the relations of the river-systems 
to the geological structure. 

The seventh and final article, on ‘“‘Cornwall, Devon, and West 
Somerset’’, is by Mr. W. A. E. Ussher, who has given accounts of 
a great series of formations from the most ancient rocks of the Lizard 
to the Pleistocene and Recent deposits. His table of strata and of 
igneous rocks, indeed, extends over more than two pages, and his task 
of summarizing the information on this varied series must have been 
an exceedingly difficult labour of love. 

The igneous rocks and the China clay are first dealt with; then 
follows an account of the Lizard from the pen of Dr. J. 8. Flett, who 
gives some of the results of his recent investigations on this complex 
group of mica-schists, quartzites, granulites, hornblende-schists, 
serpentine, gabbro, dolerite, and granite. The various schists of 
Start, Bolt, and Prawle are next described, and the author takes 
a ‘“non-committal attitude” regarding their age. The results of 
recent work on the small areas of Ordovician and Silurian and on the 
Devonian and Carboniferous rocks form the most important portion 
of the author's article. As he intimates, a good deal remains to be 
done before the grouping and relationship of all the divisions of 
Devonian and Carboniferous are determined. While he hesitates to 
accept Hicks’s view of the age of the Morte Slates, as the field-evidence 
does not favour the intercalation of Lower Devonian in the area where 
the Morte fossils were found, yet, as he remarks, ‘‘ detailed mapping 
on the six-inch scale may vindicate Hicks’s view.” 

The New Red Rocks and later deposits are described, some very 
briefly, but with special reference to recent researches. 


IV.—Yorxsuire Type Ammonites. Edited by S. 8. Bucxmay, F.G.S. 
Parts I and II, pp. i-xvi, with 24 plates and descriptions. London: William 
Wesley and Son, 1909 and 1910. Price per part 3s. 3d. net. 
f|\HE object of the present work is to give descriptions and illustra- 

tions of the Jurassic Ammonites that were named by Young & 
Bird and by Martin Simpson. It is remarked that the type-specimens 
of which sketches without descriptions were published by John Phillips 
are lost; but the majority of the specimens described and illustrated 
by Young & Bird, and those described (but not figured) by Simpson, 


Brief Notices. | 431 


are preserved in the Museum at Whitby. The Editor expects to 
deal with 150 or more species, and to complete his work in about 
sixteen parts, each containing from twelve to sixteen plates. The 
original descriptions of the fossils are reprinted, together with figures 
of the types admirably reproduced from’ photographs, mainly by 
Mr. J. W. Tutcher. 

Of special importance is the illustration of the Simpson Collection. 
The specimens, as the editor remarks, had received ‘‘ careful and 
discriminative studies”’, but without figures ‘‘it is almost impossible 
to obtain due knowledge of Lias Ammonites, and certainly dangerous 
to describe or name species as new”’. In identifying and figuring 
Simpson’s species he has rendered a distinct service to paleontology. 
Simpson, although ready to add, where necessary, to the number of 
species, was averse to the multiplication of genera, and in this he will 
have the cordial sympathy of most geologists. 

The editor gives definitions of biological, biogenetic, and other 
technical terms, also some notes on Ammonite development and on 
generic names. It is a defect that all the new names have not the 
suffix ceras, surely a convenience even for the paleo-biologist, who, 
as a rule, can alone find use for them; but the editor is by no means 
entirely responsible for this. He gives the latest of the generic 
Ammonite names, and a list of comparable species with references. 
This list is admittedly incomplete, but it might well have included 
all the names adopted by J. F. Blake. 

Among the forms figured are Ammonites mulgravius, A. exaratus, 
A. levisom, A. lythensis, and A. lenticularis; also one Nautilus, 
NV. subcarinatus. ‘To the ordinary geologist a Nautilus, however, 
is not an Ammonite. We trust that the editor will be well supported 
in his undertaking. 


V.—Brirr Notices. 


1. Yorxsuire Fossirs.—Messrs. H.C. Drake & Thos. Sheppard have 
published in the Proceedings of the Yorkshire Geological Society, 
vol. xvii (1), 1909, a ‘‘ Classified List of Organic Remains from the 
Rocks of the Kast Riding of Yorkshire”, post-Glacial to Lias. This 
laborious piece of work aims at ‘‘ placing in a convenient and compact 
form all the various and scattered records that have been published ”’. 
No attempt has been made to revise the nomenclature, as it was felt 
that the older names would be more familiar to searchers. It is now 
easy to ascertain whether a given species has been previously recorded, 
and the reference to the authority and the place of publication have 
been indicated. 


2. Department oF Minzs, Canapa.—The Summary Report of the 
Geological Survey Branch of the Department of Mines, Canada, for 
1909, issued 1910, contains .much useful information on various 
subjects and localities. In his Report the Director, Mr. R. W. Brock, 
remarks that although the work undertaken by the Survey has been 
along strictly economic lines, the geologists are not engaged in 
prospecting. Thus ‘‘The Government geologist may recognize and 
direct attention to mineralized districts that afford promising ground - 


432 Correspondence—Ur. G. E. Dibley. 


for prospecting, and furnish information regarding the geological 
conditions and mode of occurrence of minerals, that will form 
serviceable guides to the prospector; but only rarely can a geologist, 
engaged in his legitimate work, actually discover important bodies of 
economic minerals”. He rightly observes that ‘‘ Negative results 
are, in their way, quite as valuable as positive”, inasmuch as they 
discourage fruitless enterprise. Some important discoveries, however, 
have been made of coal-bearing strata in the Whitehorse district and 
in Alberta. Reports on the Yukon Territory are included, and it is 
remarked that the conditions in the Stewart River district appear 
to be favourable for placer mining. The results of borings on Prince 
Edward Island prove that Carboniferous rocks do not occur within 
2000 feet of the surface. 

Since the death of Dr. J. F. Whiteaves, the Paleontological work 
has been carried on by Mr. Lawrence M. Lambe, aided by Mr. W. J. 
Wilson. 

A separate Annual Report of the Division of Mineral Resources and 
Statistics on the Mineral Production of Canada is published by the 
Department of Mines; that for the two years 1907 and 1908, by 
Mr. John McLeish (issued 1910), includes particulars relating to 
metallic ores and non-metallic products. Among the latter are 
abrasive materials, asbestos, coal, peat, gypsum, mineral water, 
natural gas, petroleum, and salt. 

We have received copies of two separate Geological Survey memoirs— 
A Reconnaissance across the Mackenzie Mountains, by Mr. Joseph Keele, 
1910; and Geology of St. Bruno Mountain, Province of Quebec, by 
Mr. John A. Dresser, 1910. 


CORRESPONDENCE. 


MARSUPITE CHALK IN SURREY. 


Srr,—About two years ago I recorded the discovery of the 
Uintacrinus Chalk at Orpington, Kent. During the summers of the 
following years I traced this zone through Holwood Park to West 
Wickham, and also succeeded in finding the Marsupite zone in these 
last-named localities. Throughout the same period I also worked the 
roadside chalk at Farnborough Hill without any definite result. In 
June of this year I turned my attention to the chalk in the lane 
leading from Farnborough to High Elms, having a strong suspicion 
that this band of chalk would prove to be connected with Orpington 
and Holwood Park. My efforts were quickly rewarded, and in three 
visits I secured a characteristic fauna and numerous plates and arm- 
ossicles of DMarsupites from the upper end of the lane. I hope 
subsequently to publish the results of these and other workings — 
during the past few years. 

G. E. Drier. 


46 Bur@uitt Roan, 
Lower SypenHam, 8.E. 


GEOLOGICAL MAGAZINE 


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| MmremmyaeR Gr... 5s. . 438 By Miss G. R. Watney and Miss 
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ORIGINAL ARTICLHS. 
pL Se Se 
I.—Tue Srructure oF GLACIERS. 
By R. M, Dezztzy, F.G.S. 


li August, 1841, Professor J. D. Forbes, in company with Professor 

Agassiz and Mr. Heath, spent some time upon the Lower Glacier 
of the Aar, and Forbes states that it was then for the first time that 
he noticed the veined or ribboned structure of glaciers. Although the 
description given in the communication he made to the Royal Society 
of Edinburgh in December of the same year is most interesting, he 
does not state clearly how the structure is related to the glacier grains 
of which the ice streams are built up. 

During the several visits I have paid to Switzerland for the purpose 
of studying the structure of glacier ice the relationship between the 
form and size of the ice grains and the superficial effects produced by 
their weathering have been carefully noted. 

Except at high altitudes the granular structure of the ice can only 
be properly studied in the ice caves which have been excavated for 
the attraction of tourists. At low levels the glacier surface is much 
disintegrated by the warm air and sun, and its appearance will be 
found to depend upon the size and shape of the glacier grains or the 
inclusion of air bubbles. Although Forbes frequently speaks of the 
veined or ribboned structure as though they were one and the same 
thing, the ribboning is rather a feature of the glacier surface when 
the veining is well developed. 

Stratification.—In cases where the vertical unweathered faces of 
glaciers are exposed, such as those which are formed by the breaking 
away of the ice of hanging glaciers, the ice is seen to be horizontally 
stratified, the white layers being those portions of the ice which 
contain an excess of air bubbles imprisoned in the mass. 

If the surface of the névé were always in a powdery loose condition 
at the surface it is likely that, as the mass became consolidated, the 
air would be almost wholly expressed and very blue clear ice would 
be formed. Glaciers, where clean vertical surfaces are exposed, vary 
much as regards blueness, the air bubbles where they are numerous 
making the ice appear more or less white in appearance. 

The transformation of the snow into ice is the result of the slow 
growth of some crystals and the disappearance of others, and to the 
viscosity of the crystals in a direction at right angles to their optic 

DECADE Y.—VOL,. VII.—NO. X. 28 


434 R. WM. Deeley—The Structure of Glaciers. 


axes. The consolidation must also be facilitated by the slow melting 
of the points of contact of granule with granule, due to the lower 
melting-point of the more stressed portions. Time is therefore an 
important consideration, as also is temperature, in the process of the 
consolidation of snow consisting of a great number of ice spicules, etc., 
into glacier ice consisting of a much smaller number of large 
crystalline grains. 

The Antarctic Great Barrier, Professor T. W. E. David says, is 
composed of highly compacted snow rather than glacier ice. From 
measurements of the snowfall on it and the rate of flow he concludes 
that the ice at the depth of 900 feet at the Barrier face is only 
900 years old. As the visible face is only about 120 feet high the 
oldest ice seen is therefore 120 years. To what extent the snow has 
really been converted into glacier grains we are as yet unable to say. 
It, however, clearly contains a very large number of air bubbles 
which give it the appearance of compacted snow and much reduce its 
density. 

In most instances the névé surface is melted by the sun or warm 
air. In this way more or less impervious layers of ice are formed, 
which prevent the escape of the imprisoned air. 

One of the first impressions produced on the mind on entering an 
ice cave is the solidity and blueness of the ice. One, however, soon 
notices white discontinuous layers, generally roughly parallel with 
the glacier bed, but much twisted and broken. These are the 
stratifications produced in the névé by the imprisoning of air bubbles. 

Although the mass of the ice consists of glacier grains of all sizes 
and shapes the bubbles bear no relationship to either the size or the 
arrangement of the grains. The great majority of the bubbles are 
enclosed in the ice granules. Only occasionally are they seen at the 
interfaces. It would seem that as the crystals grow or decrease in 
size and the positions of the interfaces alter the bubbles are not 
displaced. 

It is only at great elevations, where ice falls from hanging glaciers 
and thus exposes fresh clean surfaces, or in ice caves that 1 have seen 
the regular stratification due to imprisoned air. In the mévé it is 
very clearly marked, but lower down in the glacier the differential 
motion, the opening and closing of crevasses, ete., give rise to great 
distortion of the white layers. 

Veining.—A careful examination of the walls of an ice cave will 
reveal the fact that the glacier consists of an agglomeration of ice 
granules, the outlines of the granules being clearly defined by the 
delicate lines on their surfaces or the melting along the lines of 
contact. If a thin piece of notepaper be placed against the ice and 
the surface of the paper be rubbed with a pencil a rough copy of the 
surface markings is obtained. The granules vary in size very much, 
the glacier being composed of beds of granules of varying coarseness. 

In a paper communicated to the Guonocicat Macazrye by Mz. G. 
Fletcher and the author we say ‘‘the veining resulted partly from 
the arrangement of the crystal grains and partly from a variation in 
the shape of the grains and partly from variations in their 
dimensions ”’ 


oe 


R. MW. Deeley—The Structure of Glaciers. 435 


Except in ice caves, the very deep portions of crevasses, or beneath 
the moraines or large stones on the surfaces of the lower glaciers the 
ice is seldom seen in its blue compact condition. The effect of the 
sun upon the surface of a glacier is to break up the compact ice into 
loose crystalline granules. The principal effect of the sun is therefore 
to separate the granules by melting them at their interfaces. It is 
not necessary to postulate the presence of sodium salts in the ice to 
account for the rapid melting at the interfaces. At the interfaces the 
molecules are in an abnormal condition of strain, and are more easily 
set free (melted) than are those in the interior of the granules. Many 
of the interfaces are the result of slow shear without fracture bringing 
part of one grain against another, and in such cases there is surely no 
likelihood of the presence of foreign salts. 

When not subjected to severe strains the larger ice granules grow 
in size at the expense of the small granules, which disappear. Where 
the strains are great, however, the large granules are broken up into 
smaller ones again. This breaking up of the granules occurs in layers 
of more or less considerable thickness in directions parallel with the 
motion of the glacier, which thus becomes composed of layers -of 
granules of varying coarseness. ‘The heat of the sun shining on the 
glacier disintegrates the grains, and the smaller these are the whiter 
the glacier surface appears, and the larger they are the bluer the 
surface appears. A large transparent bluish crystal, for instance, if 
broken up will form a white powder. The blue and white veins 
seen on the surface of a glacier and passing near the sides of the 
glacier stream almost vertically down the walls of the crevasses, are 
due to the disintegration of layers of granular ice of varying coarse- 
ness. That this is the case I have proved by cutting away the 
disintegrated white surface until firm blue ice was reached, and by 
examining the granules below blue and white veins. 

Ribboned. structure.—TYhe veined and the ribboned structures are 
generally so closely associated that they were dealt with by Forbes as 
one structure. We will leave Forbes to describe this feature in his 
own words. ‘‘I noticed in some parts of the ice an appearance which 
I cannot more accurately describe than by calling it ribboned 
structure, formed by them and delicate blue and bluish-white bands 
or strata, which appeared to traverse the ice in a vertical direction, or 
rather which by their opposition formed the entire mass of the ice. 
The direction of these bands was parallel to the length of the glacier, 
and of course being vertical they cropped out at the surface .. . 
Not only did we trace them down the walls of the crevasses by which 
the glacier is intersected, as far as we could distinctly see, but, 
coming to a great excavation in the ice, at least 20 feet deep, formed 
by running water, we found the vertical strata or bands perfectly 
well defined throughout the whole mass of ice to that depth.” It is 
these vertical strata or bands which run mainly in or near the white 
veins which I regard as the ribboned structure. Neither these 
ribbons nor the white and blue veins should be confounded with the 
stratification of the névé due to air bubbles. The ribboned structure, 
and also the veining when seen near the sides of the glacier, is 
generally more or less vertical, but in the Mer de Glace, etc., the 


436 H. Keeping—Bembridge Fossils on Creechbarrow Hill. 


structure may be seen to curve round and cross the centre of the 
glacier, forming great loops directed down-stream. The veining and 
ribboned structure are nearly parallel with the sides and bottom of 
the glacier, and where the surface is being rapidly melted the lower 
horizontal veins near the middle come to the surface and form these 
loops. Forbes appears to be quite correct when he says ‘‘ the vertical 
structure is too close to the original strata of the névé to allow of the 
supposition that these have all of a sudden turned up vertically in 
some parts of the glacier, and disappeared in the remainder”. 

In the cave which was made in the lower portion (which has now 
melted away) of the Upper Grindelwald glacier I have seen the ice 
built up of more or less regular layers of flat ice granules, the whole 
appearing like a mass of masonry or ribbons of grains. The shear- 
planes cutting the granules and giving rise to this ribboning are 
produced by slow shear without fracture parallel to the direction of 
flow. This regular structure produced by shear is not commonly seen 
in ice caves, for they are generally excavated at the ends of glaciers 
where the rate of distortion 1s small. Where this masonry-like 
structure crops out on the glacier it discloses itself as ribboned 
structure. As before remarked it is generally parallel with the 
veined structure, and seems to make it more striking. On the Rhone 
glacier the ribboned structure is shown up by the dirt which settles 
in the parallel fissures produced by the melting of the ice along the 
shear-planes. Where streams cut into the ice it is frequently well 
shown. 

Both the veined and ribboned structure will be found most perfectly 
developed when the glacier is moving rapidly and the internal strains, 
i.e. rate of distortion, is greatest. When a glacier widens, becomes 
thin, or for any reason moves slowly, the slow alterations which are 
constantly taking place in the shape of the grains gradually obliterates 
the structure. Owing to the motion the structure is also carried to 
portions lower down the glacier than those where it is being 
produced, and in crevassed areas the veins and ribboned structure 
are twisted about in a very striking manner. The time required for 
the grains to appreciably alter their form and size must be measured 
in years. 


IJ].—On THE piscoveRY oF BrmpripceE Limesrone Fossmzs on . 


CreecHBArrow Hitz, Iste or PurBecx. 


By Henry Kenrine, Sedgwick Museum, Cambridge. 
(PLATE XXXIV.) 

HEN last year I had an opportunity of examining a few rocks 

and fossils from the limestone of Creechbarrow Hill, which the 

late Mr. W. H. Hudleston considered of Bagshot age, I at once 
suspected that they belonged to the Bembridge Limestone. Upon 
my pointing this out to Professor Hughes he requested me to go down 
to examine the ground, which I did in November of last year, but 
I found only the same fossils which Mr. Hudleston had recorded, namely, 
Melanopsis and Paludina. On my return to Cambridge I expressed the 
opinion that better evidence would probably be obtained if a few 
openings were made here and there, and the Professor arranged that 


| 


H. Keeping—Bembridge Fossils on Creechbarrow Hill. 437 


I should carry out a further examination of the area at a more 
convenient season. This I have done, and I now offer the results of 
my further researches. 

After getting permission from the owner of the land, G. W. 
Bond, Esq., and his tenant, Mr. Trent, I commenced by making an 
opening on the south side, and also spent some time in the pit which 
Mr. Hudleston had made, but I found only the same fossils as on my 
last visit. Feeling sure that the limestone must be found at a lower 
level I opened another pit, about 12 feet long, at the base of the 
limestone. At one end of this pit I found a reddish marl called by 
the workmen Cherry Marl, which I refer to the Osborne formation. 
Few or no fossils are ever found in this marl. At the end nearest the 
top of the hill we came on the base of the limestone resting on the 
marls. I recognized the section as exactly similar to that in which 
the vertebrate remains were found in the Isle of Wight, and examined 
it carefully. In about ten or twelve minutes I found part of the tooth 
of a Paleotherium. Unfortunately I had only about a yard of this 
bed exposed, but I feel sure from the character of the deposit that 
more mammalian remains might be obtained here. I then opened 


Nabi ake 
/ 


Diagram Section showing the relation of the Creechbarrow Limestone to the under- 
lying series : a, Bembridge Limestone; 4, Osborne Series; ce, Upper Headon 
Series ; d, Middle ditto ; e, Lower ditto ; f, Sands; g, Barton Beds; #, Brackles- 
ham Beds with lignite; ¢, Bagshot Beds with pipeclay; j, London Clay ; 
k, Woolwich and Reading Beds ; 7, Chalk. 


another pit on the north side of the limestone, and after reaching 
a depth of about 7 feet I found what I had been looking for, namely, 
beds of limestone which I would refer to a lower horizon in the 
Bembridge Series. These yielded good results, as I obtained from 
them Bulimus (two species), Cyclotus (two species), Helix (two species), 
Clausilia (two species), Achatina costellata, and the so-called eggs of 
Bulimus: altogether about twenty species, some of which have not 
yet been determined. The marls in the old excavations, still to be 
seen some way down the hill-side, which were explained by 
Mr. Hudleston as due to the crumbling away or waste of the lime- 
stone from the top of the hill, I believe are part of the Lower Headon 
Series, from which marl was formerly dug for manuring the land. 
A good dressing of this was supposed to last from seven to ten years. 
The marl of Creechbarrow is, however, much more sandy than any 
I have seen in the corresponding beds elsewhere. When I was a boy 
of seven or eight years of age I should say there could not have been 
less than fifty men employed at this work. I have many times 
watched them digging, and they occasionally turned up portions of 
the freshwater and mud tortoises Zrionyx and Emys. 

This marl has an extensive range and may some time be of use 


438 H. Keeping—Bembridge Fossils on Creechbarrow Hill. 


again; it extends from Whitecliff Bay to Headon Hill, by Hordle, 
Lymington, Brockenhurst, and Lyndhurst, and various other places 
in the New Forest; it is then lost until we reach Creechbarrow Hill, 
where we find it again in the disused marl-pits referred to above. 
At Cut-walk Hill, where it was once extensively worked, a part of 
the Middle Headon Series is passed through before reaching the marl. 
At the base we frequently find specimens of the beautiful little Voluta 
geminata and other marine shells. Sir Charles Lyell when a young 
man of about 17, crossing a field with some sportsmen, picked 
up several of those fossils, and about twenty years afterwards sent 
specimens to F. E. Edwards, who was then preparing his Monograph 
on the Eocene and Oligocene Mollusca. I was at that time living at 
Milford, and Mr. Edwards wrote asking if I would try to find the 
locality. This I did, and made a good collection of fossils from Cut- 
walk Hill, one mile and a half north of Lyndhurst. The Rey. O. Fisher 
and the Rey. John Compton, Rector of Lyndhurst, visited the localities 
with me and collected a considerable number of fossils. Sir Charles 
Lyell, Professor Prestwich, and Sir W. H. Flower also visited the 
place for the purpose of studying the formations. ‘The Rey. O. Fisher 
will, I am sure, corroborate my statements respecting the digging of 
the marl and the finding of the fossils at Brockenhurst, Lyndhurst, 
and elsewhere in that district. 

This, I believe, is the first time that the Oligocene formation has 
been shown to occur in the Isle of Purbeck, and it will now be seen 
that it had a much more extensive range than had previously been 
supposed. Beginning at Whitecliff Bay it runs across the larger part 
of the parish of Bembridge, over the Solent to Hordle, Lymington, 
Beaulieu, Brockenhurst, and Lyndhurst, and extends thence to 
Creechbarrow Hill, about 7 miles west of Studland Bay. When 
engaged in making a collection for the Marchioness of Hastings, 
I found at Efford Hill a disused marl-pit quite rich in vertebrate 
remains, and I there collected portions of a crocodile’s jaw with teeth, 
various mammalian remains, with Hmys and Zrionyx. These specimens 
are now preserved in the British Museum (Natural History), South 
Kensington. The marls which are found between the 400 and 500 foot 
contour-lines I regard as Lower Headon, and are the same as those 
which were formerly so extensively worked for manuring the land. 
It can now be seen that if we allow this to be Lower Headon we have 
space enough between it and the top of the hill for the Middle and 
Upper Headon, the Osborne, and the Bembridge Series. By taking the 
average level of the Pipeclay Series, say at the 337 foot contour, we 
shall leave 300 feet to the top of the hill, and allowing 50 feet as the 
thickness from the Pipeclay to the top of the Lower Bagshot Series, 
we shall have 250 feet for the Bracklesham, Barton, and the whole of 
the Oligocene; from which it will be seen that the hill may contain 
all the formations which occur in the corresponding position in the 
Isle of Wight.1. The sand and flints described by Mr. Hudleston, and 


1 The only formations which have not been satisfactorily proved to occur are the 
Bracklesham, the Barton, and the Middle and Upper Headon. I have no doubt 
that those could be found in the hill by the sinking of pits and perhaps of a few 
boreholes. 


Grou. Mac. 1910. Pratt XXXIV. 


1. A. Brock cel. 
Fossils from the Bembridge Limestone, Creechbarrow Hill. 


Professor J. B. Harrison—‘ Laterite’ in British Guiana. 489 


considered by him to be of Lower Bagshot age, I regard as Pleistocene 
drift, such as may be met with in many places, not only in the Isle of 
Purbeck, but in the New Forest and the Isle of Wight. At the Rabbit 
Warren at Headon Hill there is nearly or quite 100 feet of sand and 
flint gravel, the flints being in every respect exactly similar to those 
from Creechbarrow. One of the workmen picked up, at a depth of 
about 13 feet, in one of the pits a piece of Bembridge Limestone 
associated with the flints in the gravel, which is quite conclusive 
evidence that the gravel cannot be of Bagshot age. 

In conclusion, T should like to thank Mr, A. H. Bloomfield for 
valuable assistance, and to assure any persons visiting the Isle of 
Purbeck for the purpose of studying its stratigraphy or collecting 
fossils that they would do well to secure his services. 


HXPLANATION OF PLATE XXXIV. 


Fossils from the Bembridge Limestone of Creechbarrow Hill, Purbeck, in the 

Sedgwick ah Cambridge, collected by H. Keeping. 

Fics. 1, se omus [ Bulimus] ellipticus (Sowb.). 1, with shell preserved ; 
2, internal cast. 

Egg of Amphidromus (?). 

Cyclotus cinctus, Edwards; x 13. 

Felix ocelusa, Edwards. 

Glandina |_Achatina| costellata (SowD.). 

Clausilia striatula, Edwards. 7, natural external cast, x 14. 8, wax 
impression of external cast, x 13. 


CO > Orie O° 


Iil.—Tue Resrpvat Earrus or BrivisH GuiaNaA COMMONLY TERMED 
‘ LATERITE ’. 
By Professor J. B. Harrison, C.M.G., M. As F.G.S., F.1.C., assisted by 
K. D. Rep, Assistant Analy st British Guiana. 

N pages 20-2 and 99-105 of the Geology of the Gold Ields of 
British Guiana I gave a condensed account of the residual earths 
derived from the gradual decomposition of igneous rocks in situ which 
characterize wide areas in British Guiana as well as in the neigh- 
bouring countries of Venezuela, Dutch Guiana, French Guiana, and 
Brazilian Guiana. This deposit forms in many places a widespread 
very thick blanket-like coating to the igneous rocks from which it is 
derived, and owing in many “places to its striking resemblance in 
general properties to the typical Indian formation described by 
Buchanan in 1807 it has been alluded to by many authors and by 
numerous mining engineers as ‘laterite’. I gave on p. 101 two 
analyses of lateritie deposits which I selected from many I had made 
as showing the general composition of the earths. Unfortunately 
I omitted to show in them separately, as I had done in the original 
analyses, the proportions of silica present as quartz and of that present 
in a combined state. If I had done this it would have been seen that 
the earths contained but little combined silica and a relatively high 
proportion of alumina presumably present in the state of hydrate. 
For instance, in the Tumatumari sample which I collected myself from 
a deep cutting in the laterite lying on the diabase of the Tumatumari 
cataracts a few feet only above the surface of the unaltered rock, out 
of 51°76 per cent. of silica 49°35 is in the form of quartz, leaving 
2°41 per cent. in the combined state in the presence of 24°55 per cent. 


440 Professor J. B. Harrison—‘ Laterite’ in British Guiana. 


of alumina. I drew attention to this in a report on the soils of the 
interior of British Guiana published in 1902 in the following words: 
‘A very large proportion of the alumina present is in the form of the 
hydrate, bauxite.” As in the work on the Geology of the Gold 
Fields I was not dealing with the question of the presence of free 
alumina in the decomposition products of igneous rocks, but with the 
movements, the segregation, and the concentration into grains of the 
gold originally disseminated in certain of them, I contented myself by 
giving a reference to the full account and discussion of the Guiana 
laterites in Dr. G. C. Du Bois’ monograph ‘ Beitrag zur Kenntnis der 
Surinamischen Laterit”’, which was published in 1903 in Zschermak’s 
Mineralogische und Petrographische Mitteilungen. A reference to this 
work would have shown that aluminous masses occur in the laterites 
of the Guianas and in Surinam, more especially in the re-arranged 
detrital deposits classed by Du Bois as ‘alluviale laterite”’. 
Unfortunately a reviewer of the work in the Imperial Institute 
Bulletin, vol. vu, No. 1, 1909, did not realize my object in thus referring 
to Du Bois’ monograph, and therefore made unfavourable comments 
on my use of the term ‘laterite’, which term he stated ‘‘should be 
restricted to that product of weathering in hot moist climates which 
contains free aluminium hydroxide ”’. 

His comments have given rise to the recent correspondence between 
Mr. J. B. Secrivenor and Mr. T. Crook, in which the latter writes 
somewhat scathingly of ‘‘some people”, amongst whom I am not 
ashamed to be included, who use the term laterite in the wide sense 
it is at present very largely employed by technical geologists, mining 
engineers, and tropical agriculturists. But in my opinion Mr. Crook 
is too severe in his strictures, strictures which appear to be based on 
a somewhat restricted view of the nature of the deposits in question, 
on the assumption that they mainly consist of masses of hydrated 
alumina—bauxite, gibbsite, or diaspore, or mixtures of them—which 
actually occur only in places in laterite; and I am quite unable to 
agree with him that the application of the term to such clays, iron- 
ores, etc., as I used it for is ‘‘ wholly unwarranted ”’, and that my use 
of the term is “‘ unscientific’? and one that ‘‘ cannot properly be 
adopted by geologists”. The British Guiana deposits are ‘‘ a complex 
product .. . characterized by the presence of hydrated alumina, but 
usually containing also notable amounts of titanium and iron oxides, 
whilst free silica is generally present and hydrate of silicate of alumina 
is not necessarily absent”, and the following account of these deposits 
formed by the decomposition of igneous rocks in situ and in some of 
which in parts hydrated alumina occurs may be of interest. 

As far as my experience goes, the presence of free alumina in 
quantity in the residual earths resulting from the decomposition of 
igneous rocks in British Guiana characterizes rocks the felspars of 
which are mainly of the albite-anorthite series, whilst the residual 
deposits from rocks in which alkali-felspars such as orthoclase, 
anorthoclase, microcline, and albite are predominant, consist largely of 
kaolinite or of sericitic micas with kaolinite. 

The general compositions of the soils found in aluminous lateritic 
areas are shown in the following analyses :— 


— ~~. 


‘ Laterite’ in British Guiana. 441 


1son— 


fessor J. B. Harr 


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442 Professor J. B. Harrison—‘ Laterite’ in British Guiana. 


The analyses of the soils were made in the manner usual in 
analysing them. The soils were digested in hydrochloric acid 
containing 20 per cent. of real acid at the temperature of boiling 
water for five working days, and the determinations of the constituents 
dissolved were made by well-known processes of analysis, a description 
of which it is not necessary to give here. 

Although the analyses are of value as indicating the general 
characters of the soils on the residual earths in the lateritic areas and 
as showing in some cases the presence of alumina in a state or states 
in which it is readily dissolved by hot diluted hydrochloric acid in 
higher proportions than are usually dissolved from either temperate 
or tropical soils, it is evident that they do not indicate whether the 
alumina which is soluble in hydrochloric acid is present in the form of 
hydrate or as fairly easily decomposable silicates. 

As I pointed out in a paper on the Oceanic Rocks of Barbados 
(Q.J.G.S., vol. xlvii, May, 1892, pp. 190, 191), the action of hydro- 
chloric acid in the silicates present in earths and clays is dependent 
for its extent on variations in the strength and the temperature of the 
acid and in the duration of its action. This is true also of other 
acids. It is not feasible as far as my experience goes to regulate 
these factors so that only the uncombined or hydrated alumina 
present in an earth is dissolved without any of the aluminous silicates 
being attacked and supplying some of their alumina for solution in 
the acid. Hence it is necessary in the study of the earthy decom- 
position products of rocks with the view of ascertaining the nature 
and proportions of their proximate components to analyse them by 
methods which ensure their complete decomposition, and guided by 
the indications of microscopical examination of the earths to calculate 
the proportions of their proximate constituents by means of the figures 
obtained by the analyses. 

Aided to a very great extent by Mr. K. D. Reid, an Assistant 
Analyst in the Department of Science and Agriculture of British 
Guiana, I have made in addition to earlier ones a series of more 
complete analyses by following with some additions and modifications 
the methods I described in papers dealing with the compositions of 
the oceanic rocks of Barbados and of certain oceanic oozes (Q.J.G.S., 
vol. xlviii, pp. 182-8, May, 1892; vol. li, p. 314 et seq., August, 
1895). | 

In the discussions which follow in this paper the probable proximate 
composition of the samples which have been examined have been 
calculated on the assumption that the minerals present are in the 
condition of maximum hydration corresponding to the proportions of 
water found in the samples, that the potassium, sodium, and calcium 
oxides! found therein are in the form of felspars or of sericite, 
according to the indications of microscopical and physical examinations ; 
the magnesium oxide has been calculated to tale, its most stable form 
of hydrated silicate under weathering; the portion of the combined 
silica not required in these combinations has been calculated to 


* Calcium oxide is usually found in very small proportions, and in the residual 
earths is generally present as a constituent of epidote. 


Professor J. B. Harrison—‘ Laterite’ in British Guiana. 443 


Kaolinite,’ whilst the residuary alumina unallotted to them has been 
assumed to be present as aluminium hydrate, the composition of the 
hydrate being dependent on the relative available proportions of 
alumina and of water; and the hydrate so calculated for convenience 
has been termed bauxite—a possible terminological inexactitude which 
I trust will be condoned by Mr. Crook. 

In samples which showed the presence of an excess of water, after 
allowing for the various hydrated aluminous and magnesian minerals 
assumed to be present, the excess of water has been calculated as 
combined with iron peroxide to form limonite. I have not attempted 
in cases where the excess of water is insufficient to combine with all 
the iron oxide, other than that present as ilmenite, to form limonite, 
to show the iron oxide as one of the ill-defined reputed hydrates of 
iron, but have regarded it as being in the form of mixtures in various 
proportions of hematite and limonite. The titanium oxide has been 
shown as present in the form of ilmenite, a mineral very resistant to 
decomposition under the conditions existent in the Guianas, and 
constantly found in the residual earths and the ferruginous and 
aluminous concretionary masses. 


Tue Restpuat Propucts or THE WEATHERING OF ROCKS OF THE 
DraBasE-GABBRO TYPE, 


To ascertain the nature of the residua resulting from the decom- 
position in situ under tropical conditions of basic igneous rocks, 
a study has been made of the various components of such decom- 
position-products at the Agricultural Experiment Station of this 
Department at Issorora Hill, part of the Aruka range, which is 
situated about 17 miles from the seashore, in the north-western 
district of British Guiana, about 180 miles to the north-west of 
Georgetown, and about 10 miles from the Venezuelan boundary, the 
Amacura River. This isolated range of low hills, which extends for 
about 20 miles in a south-westerly direction, consists of epidiorite and 
of hornblende-schist, the metamorphosed products of a diabase or 
gabbro, which are covered by a blanket-like coating of red earth with, 
in its upper layers, numerous blocks of concretionary ironstone, and 
this covering supplies an excellent example of the material not 
unfrequently described as laterite by agriculturists, engineers, and 
mining experts. 

Examination in the field shows that the covering consists of 
a gravelly bright-red earth, similar to that which is termed in Brazil 
terra roxa and in Venezuela cascajo, in which is embedded masses of 
concretionary ironstone, varying greatly in size, in colour, and in 
texture, but usually being ruddy, scoriaceous, cindery, or slaggy- 
looking masses, with innumerable small cavities; large angular masses 
of white quartz, and numerous small pisolitic granules of ironstone. 
Concretionary ironstone of the kind above described is known in 


1 The statement that kaolinite is never a product of weathering but is always due 
to deep-seated changes cannot be accepted for the Guianas, where granitic and similar 
rocks are found converted by surface changes (weathering) into quartziferous kaolins, 
and the various stages of such conversion can be readily followed in the field in many 
places. 


444 Professor J. B. Harrison—‘ Laterite’ in British Guiana. 


Surinam as (akerlogston, in French Guiana as Roche d Ravet, and is 
termed in Brazil Pedra de ferro and in Venezuela Moco de hierro. 
Samples of the various types of ironstone, of the quartz and of the 
earth with its ferruginous pisolites, which are present in it to the 
extent of 45°8 per cent. of its weight, were collected at my direction 
by the officer in charge of the station, and have been examined by 
Mr. Reid and myself in the Government Laboratory of British Guiana. 

The ultimate composition of the epidiorite at Issorora, of the red 
earth, of the pisolitic ironstone granules, and of the various types of 
the concretionary ironstone found there was determined with the 
results shown in Table III (p. 445). 

Aided by microscopical examinations of the material the mineralogical 
components of the rock and of its decomposition-products have been 
calculated as shown in the following table :— 


Taste II. 
Red Concretionary Ironstones. 
Lateritic| Iron- 
Epidiorite. | Earth. | stone 
Nos. 1 | Pisolites.| Nos. 1 | Nos. 3 | Nos. d 
and 2. and 2. | and 4. | and 6. 
Quartz . me a eres Log} 2°3 14 Oil oi “il! 
Colloid Silicw. F 
Orthoclase 5 8 119s} 
Plagioclase , 55:1 2°9 “4 1198} 6 8 
Hornblende and Pyroxene 38:0 nil 
Magnetite Se Ants 2°8 
Hematite. ee he as P}07/ 65°4 18°2 29:0 19°0 
Limonite . ahne 15°9 74:1 54:0 12°5 
Mlmvenihete ink See wee NZ 4°3 36 6 6 6 
Kaolinite Sots Say and 39°4 37 2-4 77 24°5 
gna] Crain ae lee, Ae A ya) ea 2°3 Hh 1-4 or 8 
*Bauxite . . Aen 94°2 7c 1:6 6°6 41°7 
*Minor constituents Saat ok 6 3) 3 
100-0 1001 | 100°0 | 100-0 | 100-3 | 100-0 
IDI 6 oo 6 6 | 12:0 6°6 
Gubbsitemenmne | 12°2 WL 1:6 6°6 35°1 
*Total Alumina present in 18°9 THiS? 1:0 3° 28°6 
Bauxite 


The foregoing representatives of the class of more or less ferruginous 
and aluminous deposits which in the Guianas for many years commonly 
have been termed ‘laterite’ do not possess, except in the case of the 
concretionary ITOHSLONES, the property laid down by Buchanan as — 
being characteristic of ‘laterite’—that of ‘setting’ or hardening on 
exposure to the atmosphere. Parts of them agree to some extent 
with what has been laid down as the modern scientific qualification 


445 


Professor J. B. Harrison—‘ Laterite’ in British Guiana. 


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446 Professor J. B. Harrison— Laterite’ in British Guiana. 


for a rock to be termed ‘ laterite ’—the fact that they are ‘‘ essentially 
characterized by the presence of free hydrate of alumina”; but the 
question remains: If it is allowable to term ‘laterite’ the earth and 
its pisolites which contain, in round figures, 24 per cent. of ‘ bauxite’, 
and the concretionary masses which contain 42 per cent. of it, what 
are their accompanying masses which contain only from 2 to 7 per 
cent. of bauxite to be called? Are we to find another name for these 
masses whilst they are in situ, or may we not reasonably include 
them with the other components of the residuary products of the rocks 
as a whole under a wide-meaning term ‘ laterite’ ? 

Another type of the deposits formed by the decomposition of 
diabase and of hornblende-schist in situ is illustrated by samples from 
Tumatumari, Potaro River; the Penal Settlement at Mazaruni, 
Mazaruni River; and the Omai Falls at the Omai Gold Mine, 
Essequibo River. Their compositions and those of the rocks from 
which they are derived are as follows :— 


TABLE LY. 


| Tumatumari. Omai Falls. Mazaruni. 

| Diabase. | Laterite.| Diabase. | Laterite. Hong Laterite. 

| | chist. 

| 
Quartz . « | 3320 47°36 6°50 38°66 7°60 32°51 
Colloid Silica | 06 19 “0: 
Combined Silica 47°99 3°30 46°75 | 7:90 44°10 14°93 
Aluminium Oxide 15°80 26°38 i7°16 | 18°41 15°94 84°14 
Iron Peroxide 3°08 10°67 4°27 22°35 3°84 
Iron Protoxide . . 11:20 8:26 8:26 T1056 
Magnesium Oxide . 5°63 All 6:10 |} 12 5°54 
Calcium Oxide . 9°58 93 7:46 | 11 9-60 
Sodium Oxide 2:09 14 2°50 | “5, 1°87 
Potassium Oxide . . . 0°60 “21 0°69 | 47 “08 
AWiaber ciated teaser o's sre |e, LO8S0 11°28 0-32 | 10-97 “30 
Mitannum Oxide. 5. . 0:40 67 0°32 +50 *30 
Phosphoric Anhydride . 0°008 | trace trace | trace ‘O1 
Manganese Oxide . . . | trace nil 0-12. | — nil trace 
| 
| | 
| 99-878 | 108-71 | 10045 | 99°81 99°74 100-32 
| 


The mineralogical components of the rocks and of their resultant 
laterites have been calculated as shown in Table V (p. 447). 

These residual earths are as characteristic of many of the residuary 
products of basic rocks as those at Issorora are of others. But in 
them, in place of the silica segregating out into masses of quartz, and 
only occurring to a very limited extent as fine gravel or sand, the 
quartz occurs in quantity as very fine angular gravel and sharply 
angular sand of very varying degrees of division, but mostly of 
exceeding fineness, dispersed through the mass, by far the greater part 
of the quartz being of secondary origin. In them, as a rule, the 


Professor J. B. Harrison—‘ Laterite’ in British Guiana. 447 


concretionary ironstones are less in evidence than they are at Issorora, 
but in time the weathered surfaces of the earths become covered by 
quartz-sand and gravel, with in places pisolitic granules of con- 
eretionary ironstone, whilst they contain here and there in their upper 
parts masses of concretionary ironstone, some of which attain weights 
of over a ton, and which masses, as are some of those at Issorora, 
are in parts more or less bauxitic. 


TaBLe V. 
Tumatumari. Omai Falls. Mazaruni. 
Diabase. | Laterite.| Diabase. | Laterite. pee ien de Laterite. 
chist. 
@uantzgaes Be 372 47°3 Cron I 887, 16 32°5 
Colloud)Silica 2. OC. ail 2) 
Onihoelase: 3 3s 5 rai % 373 13} 3°9 2°8 25) 2°8 
BineIOease 49:8 2°3 40°6 1:8 30°9 4:5 
Hornblende and Pyroxene 38-0 42°2 53°9 
INGAAS Sop SROs 4-4 6°3 5°6 
iieematite: 0 6) Sk 10:0 12 6°7 
amioniere Git aoa. 7D 
Mente Melee ae el ow iis 0:8 ios} 0-6 9) 0°6 127/ 
Gaolimiters, a vce a es i3} 10°1 20-1 
Salle 51 Ne a ai “4. a3 
1 BTUORIINS). eet th lk 36:0 20°5 31°5 
*Minor constituents. . . 0°5 oy 0:9 
. 100:0 100°3 100°1 100:0 100°0 100°1 
*Diaspore . Ome 24-0 
Gibbsite MAN 30°8 20-5 °5 
*Total Alumina present in 25-0 13°4 25°3 
Bauxite 


As a rule they do not show the hardening properties of Buchanan’s 
laterite, but if we are to take the presence of free alumina in the form 
of hydrate as the definitive test of whether a mass has a right to be 
termed ‘lateritic’, they are clearly lateritic earths. 

The Residual Earths from Serveite and Chlorite Schists— As examples 
of a type of residuary earths which exhibit to a considerable extent 
the setting properties from which Buchanan derived the term laterite, 
may be adduced certain ferruginous earths which contain sericitic 
micas in such quantities that the principal aluminous components 
are sericite, kaolinite, and bauxite, instead of being kaolinite and 
bauxite, with a little residuary felspar, as are those of the types 
already considered. The best examples of these I have seen 
occur at the Omai Gold Mines, Essequibo River, where a ditch 
between two and three miles in length and several tunnels were 


448 Professor J. B. Harrison—‘ Laterite’ in British Guiana. 


cut through them for the purpose of conveying water for the hydraulic 
workings. Their mass was quite soft when first dug into, but 
gradually became indurated on exposure to the atmosphere to the 
consistency of soft rock, so that the sides of the ditch and the sides 
and roofs of the tunnels became firm enough to allow of the rapid 
passage of water along and through them without any artificial 
supports being required either for the sides of the trench or the roofs 
of the tunnels. 

The hardening was accompanied by a gradual darkening in the 
colour of the rock, this indicating changes in the states of hydration of 
the oxides of iron present in them. 

At Omai these earths are largely the residua from the decomposition 
of sericitic and of chloritic schists, which latter frequently contain 
sericite in considerable proportions. 

At Omai the rocks are completely decomposed to depths of 100 to 
150 feet, and owing to this and to the intricate nature of the complex 
of sericitic, hornblendic, and chloritic schists, epidiorites and porphy- 
roids, traversed by veins of sericitized aplite and felspar-porphyrite 
and by sills of diabase, it is not possible to ascertain which rock or 
rocks by decomposition gave rise to the sericitic earths. Hence 
I have not analysed the specimens of sericitic and other schists of 
which the cores of the diamond-drill borings obtained at Omai largely 
consist, and therefore it is not feasible to contrast the compositions of 
the residual earths with those of the rocks from which they have 
been derived. 

The ultimate compositions of representative samples of the sericitic 
earths are as follows :— 


Taste VI. 
3 
Brownish Yellowish Yellowish . 
red. brown. brown. Purplish red. 
Oyen J oc. 6 6 ai 31°44 37°28 7°05 
Colloid Silica 30 “14 “23 “08 
Combined Silica . . 24°04 19°58 16°54 14°53 
Aluminium Oxide. . 23°94 27:21 24-98 21°34 
Iron Peroxide . . . 24°65 8:78 7:57 39°03 
Magnesium Oxide. . “30 23 nme “21 08 
Calcium Oxide. . . 10 06 06 05 
Sodium Oxide... . 10 trace | trace “25 
Potassium Oxide . . ODT 1-56 | 1°85 2°58 
Wiater’ ot Sees 11°70 7g) WORT 13°22 
Litanium Oxide . . 2°31 6d | ‘70 DOYS) 
Phosphoric Anhydride trace trace | nil nil 
Manganese Oxide. . nil nil nil trace 
| 
| 99°88 99°43 100-69 100°56 


The average proximate mineralogical composition of the earths when 
calculated out in the manner already described is as follows :— 


Professor J. B. Harrison—‘ Laterite’ in British Guiana. 449 


Taste VII. 

Quartz . ; Oiler 
Colloid Silica . =) 
Sericite ; 16°9 
Hematite 2°6 
Limonite 18:6 
Ilmenite . 2:9 
Kaolinite. 23°0 
Tale 7 
*+Bauxite . 13°5 
100°1 
*Gibbsite . : : ; : : 13°5 

+Total Alumina present in the form of 
Bauxite : : ; 3 8:9 


The surfaces of the residual earths are covered with ironstone, 
eravel, and conglomerates, whilst at depths of some feet from the 
surface layers of angular quartz gravel occur. In many places the 
earths are seen to be traversed by numerous thin veins of quartz, 
some of which are normal to the original schists, whilst others are 
clearly of secondary origin, their silica having been derived from the 
decomposition of the felspar and ferruginous minerals of the rocks. 

Layers of ironstone conglomerates and masses of concretionary 
ironstone similar to those at Issorora everywhere cover to a depth of 
about 25 feet the surface of the hills at Omai. Like those at Issorora 
the concretionary ironstones are in places more or less aluminous. 

Laterite from Felsite or Porphyrite, Demerara River.—At Christian- 
burg, on the Demerara River, about 58 miles south of Georgetown, 
where the Government has a Para rubber experiment station, the 
surface of the low hills is a sandy soil which rests on beds of cream-' 
coloured, reddish-grey, or red highly aluminous laterite or ‘ bauxite’. 
The bauxite is also exposed in shallows in the bed of the river between 
Christianburg and Wismar, and it gives rise to a low hill at Akyma, 
some 11 miles south of Christianburg. Microscopic examinations of 
the bauxite show that it has been derived from a felsite, a porphyrite, 
or possibly a tuff. Felsite and porphyrite are exposed in the Kumaru 
Creek close to Akyma Hill, where they are intrusive in gneiss. At 
Christianburg the bauxite apparently is underlain by a pale buff- 
coloured arenaceous clay. 

In this district generally as well as at the Christianburg and the 
Akyma Hills the surface soil over the lateritic decomposition-products 
is a sand varying from white, glistening, almost pure quartz sand, 
containing over 96 per cent. of quartz, to a brownish highly arenaceous 
soil, with from 40 to 50 per.cent. of quartz, the former variety 
containing less than 34 per cent., the latter from 2 to 6 per cent. of 
free alumina, whilst below it the subsoil contains less quartz—from 
20 to 45 per cent.—and somewhat higher proportions of free alumina, 
these ranging from 5 to about 7 per cent. 

The soil is underlain by a somewhat thick deposit, the depth of 
which has not been determined, of massés of cream-coloured bauxite, 
which in parts are more or less stained with iron, or where reddish 
grey to red in colour are more or less ochreous or limonitic. Some 

DECADE V.—VOL. VII.—NO. X. 29 


450 Professor J. B Harrison—‘ Laterite’ in British Guiana. 


masses resemble in colour and general characters the concretionary 
ironstones described under numbers 5 and 6 of the Issorora District. 
Specimens of this kind were obtained from a shoal in the Demerara 
River near Wismar, about half a mile south of Christianburg. 

The compositions of the samples of the sands, of the bauxites, of 
the underlying clay, and of the hornblende-felspar-porphyrite from 
which they were presumably derived are as follows :— ; 


Tassie VIII. 


3 Bauxite or 
Christianburg. ; 
Hornblende| TLatenite 
Felspar 
Porphyrite. Bauxite 
Sand. or Clay. | Akyma. | Wismar. 
Laterite. 
Quartz. Bi at Reis) es 34:10 96°80 "42 38°79 67 4-74 
Colloid Silica Agente as 14 53 12 62 
Combined Silica . . . 36°86 Hols} 2°29 25°50 1:92 3°58 
Aluminium Oxide... 16°64 “97 67°28 21°16 64°86 45°14 
ImonwReroxidey seen wane 0°22 64 1°53 3-74 85 23°03 
Ino Iara 4, 5 4c 1°48 
Magnesium Oxide. . . ilo) “02 07 “49 “31 31 
Calcimm Oxides = 5 = = 3°46 “08 02 “08 03 trace 
NodrmyOxides 2s... 4°39 “08 nil -48 nil nil 
Potassium Oxide . . . 0°24 “01 “08 2-00 “5 “15 
a WVialbens |p tk. site 0°68 25 27°46 6°67 30°47 21°68 
| Carbonic Anhydride ace 0°42 trace trace nil 
Litanium Oxide .. . 0°38 trace 1:07 67 “TO. |e eluale 
Phosphoric Anhydride. . 0006 "006 | trace trace trace trace 
Manganese Oxide . . . 0:10 trace nil nil nil 
100°266 99:986 | 100°36 | 100:11 | 100°138 | 100°387 


The proximate mineralogical compositions of the porphyrite, the 
bauxitic masses, and of the clay underlying the latter are as shown in 
Table IX (p. 451). 

The bauxitic masses fully correspond to the typical laterites in the 
restricted sense laid down for the late Dr. Buchanan by Mr. Crook. 
They are when first dug fairly soft, and easily trimmed into shape for 
building purposes by a trowel or heavy knife. They have been used 
for building purposes in the foundations and retaining walls of the 
Government Saw Mill at Christianburg, and also in walls at Akyma. 
After exposure to the atmosphere the masses have quickly set and 
attained a hardness corresponding in the lghter-coloured or more 
purely bauxitic parts to somewhat less than three in Mohs’ scale of 
hardness, and in the ferruginous parts to somewhat over that degree. 
The marked hardening is to a considerable extent confined to the 
exposed surfaces. 

I have examined microscopically thin sections of the bauxite masses 
from Christianburg. Their general structure is that of a metamorphosed 


Professor J. B. Harrison—‘ Laterite’ in British Guiana. 451 


felspar - porphyrite or tuff in which the original minerals with the 
exception of the ilmenite have been impregnated with or replaced by 
hydrates of alumina in an amorphous concretionary form. The 
amorphous matter is mingled here and there with very minute 
particles of quartz, and it is traversed by very thin veins of chalcedonic 
silica, some of which appears to be tridymite. The ilmenite is present 
in the form of widely, though sparsely, scattered exceedingly minute 


Tapre IX. 
Ae Bauxite or 
Christianburg. ; 
Hornblende | HiyeSitse 
Felspar | 
Porphyrite. | Bauxite 
Sand. or Clay. | Akyma. | Wismar. 
Laterite. 
Quartz . bit eee ee 34-1 . 96°8 4 38°8 37 4°7 
Colloid Silica : “TL 5 Tl 6 
Orthoclase 1:4 trace! oo) 11:8 “9 9 
Plagioclase unas 51:0 od sal 4-4 
Hornblende and Pyroxene 12:0 
Magnetite a tees 
Heematite 5 oa hee tac gee 6 b) onl oj 21°9 
WMGeMGe! Sieyy ek eo “§ PPM 1:3 1-4 2°1 
IRCAOMIMILCR Nene ee, ied 3°3 29°8 5 4°3 
Tale aes ene of) 1:6 10, 1:0 
Calettcvmmere sf. “9 trace trace 
I AUNIteN so. age “4 92°6 8-9 94°4 64°6 
*Minor constituents . an ye op) 
100-2 | 100-0 | 100-0 | 100-2 | 1¢0-1 | 100-1 
“IDMER ORE 6 Te) 1G Sesy toes 26°71 
Gibbsite: 6051. “4 66°5 2-0 Weil 6°6 
*Total Alumina present in a 65°7 69 82°3 58:0 
Bauxite ae 64:1 43°0 


1 Muscovite. 


grains, none of it, however, being in the siliceous veins. The thin 
sections examined were cut from some of the more siliceous parts of 
the bauxite. The microscopical structure of the bauxite closely 
resembles that of the ‘‘ Oolithartige Bauxit’’ of Surinam, described 
by Du Bois as follows on pp. 35-9 of his monograph “‘ Beitrag zur 
Kenntnis der Surinamischen Laterit’’ (Zschermak’s Mineralogische und 
Petrographische Mitteilungen, Band xxii, Heft 1, 1908) :— 

‘“‘Only in a very thin section of the fresh, oolite-like substance 
could the separation of secondary silica be demonstrated with certainty. 
The ground-mass of the nodules and the cement is composed of feebly 
translucent yellow substance apparently amorphous. Some of the 
concentric parts—generally the outermost—are strongly impregnated 
with microscopic granules of chalcedony. The intermediate mass or 


452 Rh. G, A. Bullerwell— Superficial Deposits 


the cementing substance of the nodules is remarkably rich in secondary 
silicic secretions. Septarian-like veins which traverse obliquely the 
nodules also show the partial silicification.”’ 

The earth underlying the bauxite at Christianburg was micro- 
scopically examined, and was found to contain a considerable proportion 
of orthoclase felspar in a very finely divided angular condition. Some 
minute angular grains showing the strie of plagioclase were also 
detected. It seems probable from this and from its chemical com- 
position that the arenaceous clay was derived from a different rock to 
that which gave rise to the bauxite, possibly from the granitite-gneiss 
which is the principal component of the fundamental complex of the 
Demerara—Essequibo district. 

(Lo be continued.) 


TV.—On rue Superriciat Depostrs ar tHe Foor or tHE CHEVIOT 
Hitts BETWEEN WooLer AND GLANTON. 
By R. G. A. Bunterwett, M.Sc. 
(PLATE XXXV.) 

Inrropuction.—Lying at the foot of the Cheviot Hills are deposits 
of sand and gravel, which, between Wooler on the north and Glanton 
on the south, cover a considerable area, occupying the greater part of 
the lower valleys of the Breamish and other tributary streams of the 
Till. They form mounds and ridges running in different directions, 
often dividing and reuniting in a very irregular manner. They are 
indicated, along with deposits at greater altitudes, on the Drift Edition 
of the Map of the Geological Survey of England (Sheets 109 N.W. 
and 110 8.W.) as “sands and gravels of Glacial age”. It is for 
the purpose of describing these accumulations and in some measure 
elucidating their source and mode of deposition that this paper is 
written. 

Lrrrrature.—Concerning these sands and gravels very little has 
previously been published. Professor G. A. Lebour, M.A., M.Sce., 
F.G.S.,! doubtfully places them along with other deposits in 
Northumberland and Durham, evidently more recent than the Boulder- 
clay, under the head of ‘‘ Upper Drift Sands and Gravels”’. 

Writing in 1872 on ‘‘Langleyford Vale and the Cheviots”’, 
Dr. J. Hardy? noted the water- worn character of the gravels. 
‘The Wooler Water,’ he says, ‘‘ works its uncertain way among 
congeries of ancient gravels and rolled masses, often disturbing and 
ploughing them up, but adding nothing to the spoils brought thither 
by earlier and more intensified agencies that scooped the channel for 
the present diminished stream.” 

Earlier still, in 1865, Mr. Tate, F.G.S.,3 in his paper ‘‘ Records 
of Glaciated Rocks in the Eastern Borders’’, pointed out the well- 
rounded gravels which had previously been referred to as Glacial 
Moraines by Dr. Buckland. 


1 Handbook of the Geology of Northumberland and Durham. 
2 Proceedings of Berwickshire Naturalists’ Club, 1872. 
3 Tbid., 1865. 


at the Foot of the Cheviot Hills. 453 


Valuable information as to the condition of the Cheviots during the 
Glacial Period is to be obtained from Mr. C. T. Clough’s memoir! 
“On the Geology of the Cheviot Hills”’, and from the paper by 
Professor P. F. Kendall, F.G.S., and Mr. H. B. Maufe, B.A., F.G.S.,? 
“On the Evidence of Glacier-dammed Lakes in the Cheviot Hills.” 

The Glacial deposits of the adjacent.country between Wooler and 
Coldstream are described in the memoir by Mr. W. Gunn, F.G.S., and 
Mr Cyl. Clough, M.A., F.G.8.° 

PuystcaL Srrucrure oF tHE Disrricr.—The range of the Cheviots 
culminates in the north-east in the granite hills of Cheviot, Hedge- 
hope, etc. ‘This granite area is surrounded by tuffs and porphyrites 
contemporaneous with the Old Red Sandstone. Between Wooler and 
the Breamish the porphyrites present a steep but curved slope facing 
E.N.E. and east, and enclose between South Middleton and Roddam 
red marls, sands, and thick beds of conglomerate.* The range is 
intersected by several valleys, the present pigmy streams in many 

cases being grotesquely out of proportion to the amount of denudation, 
and presenting a striking contrast to the more powerful subaerial 
agents of denudation originally employed in their excavation. 

Resting unconformably upon these rocks are those of the Carboni- 
ferous Senias) consisting chiefly of sandstones, grits, and impure 
limestones. They extend outward from the Cheviot area, with 
a generally gentle slope towards the east. The Fell Sandstones of 
this series form ridges and crags at considerable elevation on the 
eastern side of the ill, their rugged and steep escarpments boldly 
contrasting with the rounded form of the porphyrites rising above the 
valley on the opposite side. All the streams included in the area are 
tributary to the Till, itself tributary to the Tweed, and which in 
its upper course is known as the Breamish, taking its rise in Cheviot, 
flowing first south-east, then east, and near Hedgeley sweeping round 
in a northerly direction. 

GLACIATION oF THE CuHEvIots:—While the higher summits appear 
never to have been overridden by foreign ice, but to have acted as 
independent centres of glaciation, two foreign streams advanced upon 
the Cheviots, one from the south-west and the other from the north, 
but whether they were contemporaneous or successive is not readily 
determined. Both the eastern and southern margins have evidently 
been overridden by foreign ice up to a height of 1000 feet, as 
indicated by strize and the presence of transported boulders. 

Mr. Clough has described the foreign rocks occurring in the drift 
near Skirlnaked and pointed out a track of foreign boulders crossing 
the porphyrite hills from the north to this locality. On the other 
hand, however, the striz and boulders occurring on the south-east 
margin of the Cheviots indicate transport from the south-west. 

On Carboniferous rocks west of Black Hill, Ford Moss, Messrs. Gunn 
and Clough found striz indicating a direction from east to west. 


1 Memoirs of the Geological Surveyof England and Wales. 

* Transactions of Edinburgh Geological Society, vol. viii, 1902. 
3 Memoirs of the Geological Survey of the United Kingdom. 

+ [Basement Beds of the Carboniferous. —Ep. | 


454 Rh. G. A. Bullerwell—Superficial Deposits 


The northerly flow along the Cheviots was evidently produced by 
a deflection of this easterly or north-easterly flow from the Tweed 
Valley. On the sandstone of Bewick Hill are striations pointing 
direct north and south. 

Description oF Sanps and Gravets.—Sands and gravels cover the 
tract between the high land ahove Wooler and Glanton Pike, and are 
bounded on the west by the Old Red Sandstone conglomerates or 
~Basement Beds of the Carboniferous Series. The eastern limit is 
more difficult to define, but gravel and sand deposits abut against the 
Carboniferous rocks of Bewick Hill, and may extend into the 
Eglingham Valley. They form hummocks and meandering ridges 
continually dividing and reuniting in a most confusing and irregular 
manner, but with the long axes of the ridges most frequently running 
north and south. In the lower valley of the Breamish the sands 
and gravels are more diffused, but this may be due to subsequent 
re-arrangement by later agencies. The mounds and ridges may be well 
seen between Wooperton Station and New Bewick where the road 
crosses them, also between East Lilburn and the same station where 
the view looking towards Bewick Hill embraces a large tract covered 
with kame-formed ridges of gravel. The undulating formation is most 
pronounced in the areas adjacent to the river valleys where the deposits 
are thickest. In several cases the sands are cut through by streams 
and present steep sloping faces fronting the valleys. Such banks may 
be seen in Coldgate Water, Roddam Dean, near Kast Lilburn, and below 
Hedgeley Low Farm (Fig. 1, Pl. XX XV). The sand is composed of 
coarse irregular grains, and contains occasional well-rounded pebbles. 
The deposits generally follow the 300 feet contour-line. 


The section below Hedgeley is almost entirely of sand, but contains ~ 


limestone and porphyritic pebbles. It rises about 40 feet above the 
level of the alluvial plain. The banks may be followed for about 
a quarter of a mile and end in a spit which slopes gently eastward. 
The surface is a plateau, broken here and there into hummocks and 
hollows. 

Many of the hummocks might be described as kame-formed and reach 
the contours of 300 and 400 and in a few cases to the 500 feet line. 
This is the greatest elevation to which it is necessary to refer for the 
purposes of the present paper. Whenever the 300 feet contour is the 
limit and any opportunity whatever given for examining the contained 
pebbles these are seen to be well rounded. 

Generally speaking; coarse gravels are to be seen on the western 
boundary where the deposits abut against the Cheviots, passing into 
finer gravel, followed by sand, with sparsely occurring pebbles as they 
are traced eastward. The gravel is usually composed of material 
derived from rocks in the immediate neighbourhood (porphyrite, etc.), 
but a considerable quantity of it is evidently derived from foreign 
sources. 

Much of the district covered with gravel is tilled, only a small area, 
apart from the low marshy soil of Hedgeley, ete., being devoted to 
pasturage. Where cultivated the soil is invariably heavily charged 
with pebbles of varying texture, and in early spring after heavy rains 
the hummocks resemble nothing so much as mere mounds of loose 


: 
’ 
| 
| 


at the Foot of the Cheviot Hills. 455 


well-rounded stones. Notwithstanding the thin gravelly soil, however, 
the farmers informed me that good crops are the rule. 

Secrrons.—On the left bank of Wooler Water and following the 
300 feet contour-line, sands and gravels are exposed and may be 
examined between Karle Mill and Coldgate Mill. A few yards south 
of the former the section consists of gravel, sand, and clay, irregularly 
bedded. ‘The gravelis water-worn and rounded. False bedding which 
probably represents a rapid deposition of sand is shown by a banded 
appearance due to alternate layers of material of darker and lighter 
colour. Gravel and sand alternate irregularly with each other, and may 
be seen when the bedding is not obliterated by the falling down of the 
sand and clay from the upper portion of the section. South of this the 
entire section is sand with few pebbles. The bedding is very distinct. 

At a point almost opposite Haugh Head and a few yards below the 
bridge a section showing coarse and fine gravel with sand is exposed. 
The bedding is clear, but layers of the same texture rarely extend 
for any great distance or continue across the entire length of the 
section, which is about 80 feet. The included rocks, which are 
without exception well rounded and water-worn, are of yellow sand- 
stone, Carboniferous Limestone, and porphyrite, the largest being’ of 
arenaceous rock and measuring up to 15 feet in girth, together with 
smaller fragments of quartz, jasper, lydian stone, slate, and Silurian 
greywacke. Some of the gravel is cemented together, the cementing 
material being calcium carbonate. The coarse gravel frequently 
contains washings of fine gravel and sand. The section, which rises 
to about 30 feet above the river-level (see Fig. 2, Pl. XXXY), 
consists of the following :— 

(a) 2% feet, sand. 

(0) 23 feet, fine gravel and sand. 

(c) 6 feet, coarse > gravel. 

) 25 feet, fine gr ravel with a few large boulders. 

(e) 5 ‘feet, coarse gravel, continuous with (g)- 

a2 feet, fine gravel, bedded. 

) About 10 feet, coarse gravel, with bed of fine gravel and sand about 2 feet 
from base. There is much limestone and yellow sandstone and several 
bands of sand and dirty gravel cemented together. Some of the cementing 
matter is oxide of iron, which gives a rusty appearance to the lower portion. 

From this point up to Coldgate Mill are banks of coarse gravel and 

sand usually grass-grown and offering little opportunity for examina- 

tion. Near Coldgate Mill the deposits abut against porphyrites, just 

below the 400 feet contour-line. 

These sands and gravels form a plateau rising here and there into 
hummocks and ridges, ascending gradually to the 400 feet contour- 
line, where they abut against the porphyritic masses of Earle Hill, 
Whinnie Hill, etc. These hills are all divided by valleys, sometimes 
dry, below the 500 feet contour-line. 

Sours Mippieton to Litpurn. — Just below South Middleton is 
a dry valley through porphyrite, and like the maj jority of these valleys 
running north and south. Below this is moraine matter, which 
spreads out eastward, gradually assuming the characteristics of the 
water-worn gravels. Towards Lilburn is a long stretch of rolling 
country, over the surface of which rounded pebbles lie scattered. 


456 h. G. A. Bullerwell—Superficial Deposits 


The railway cuts one of the hummocks above the 800 feet contour- 
line. The section about 25 feet above the railway level is obscured by 
the falling gravel and sand, but the pebbles are all well rounded and 
consist of quartz, porphyrite, sandstone, limestone, etc. A few of the 
fragments retain evidence of glacial striation. 

From Kingston Dean to Roddam Dean and between the 400 and 
the 500 feet contour-lines gravels abut against a cliff of Old Red 
Sandstone conglomerate. At the entrance to Roddam Dean the 
following section is exposed for a length of about 85 feet:— 

(a) 2 feet, fine gravel. 

(6) 22 feet, sand. . 

(c) 8 feet, coarse gravel, with occasional washings of reddish-brown sand. The 


gravel is composed chiefly of arenaceous rock, carbonaceous matter, quartz, 
ironstone, porphyrite, and Carboniferous Limestone. 


The largest boulder in this section measured 2 feet in girth. Some 
of the gravel is cemented together, the cementing medium being iron 
oxide. Fossils of Carboniferous Limestone and glacially striated 
boulders occur. 

South of Roddam Dean, and between the Roddam Dean con- 
glomerates on the north and porphyrites on the south, is a large tract 
covered with sand and gravel, forming hummocks and ridges, with 
kettle-holes. The highest reach to the 400 feet contour-line. One of 
them, just below Wooperton Dean, evidently another ancient valley, is 
a kame-like ridge, about 800 feet in length, formed of coarse gravel 
and sand, the former varying from small pebbles no bigger than a pea 
to masses 27 inches in girth. 

The ridge rises some 45 feet above its base. The materials are of 
sandstone, porphyrite, granite (Cheviot), tuff, and conglomerate from 
the north of Cheviot, and are rounded or subangular. The mass 
resembles that occurring below South Middleton. A pit a few yards 
away contains sand with very few pebbles. 

Between Wooperton Dean and Brandon Dean is another ridge 
resembling the one just described. The two tiny streams occupy 
a valley once continuous, uniting the Breamish and Roddam Burn 
Valleys. Here, too, the debris passes downwards, and the sands and 
gravels are spread out over the 300 feet contour, where, however, they 
are all undoubtedly water-worn. 

Recent Depostrs.—A large area is covered with the alluvium of the 
Till and its tributary streams. This consists of loam, sand, and 
gravel. Most of the streams are still liable to flood, but evidently at 
some period, probably before the ice had finally disappeared from the 
greatest elevations, the dimensions of the swollen streams must have 
been prodigious, consequently much more of the valleys were sub- 
merged than now. The expansion of the alluvial deposits between 
Hedgeley and Wooperton may be the site of an old lake. The Randy 
Burn has an erratic course through a yellow and sometimes whitish 
clay, resembling that seen below the peat in other. lake-basins, and 
covered with gravel and peaty soil. Another large alluvial plain 
exists south of the Lilburn near Ilderton Station. Old alluvial 
terraces may be seen at Brandon and Branton. 

Occasionally amongst the sands and gravels are depressions, the 


at the Foot of the Cheviot Hills. 457 


sites of former small lakes, now containing peat lying upon a yellow 
or whitish clay. In each case streams run through the hollows, and 
by diverting the courses of these much former bog land has been 
reclaimed and is now under cultivation. 

Near Wooperton the Roddam Burn cuts through a section in which 
a bed of peat about 2 feet thick rests upon a yellowish-white clay, and 
is covered by a thick deposit of fine sand. The same section is 
continued on the other side of the railway, and from the form of the 
depression the lake must have been at least three-quarters of a mile 
in length. ‘he depression is entirely surrounded by kame-like ridges 
of sand and gravel rising to the 300 feet contour-line. 

At Lilburn is a large depression, surrounded by sands and gravels, 
containing peat in its lowest part, and surrounded by a tract of peaty 
soil. It is drained by a small stream running right through the peat 
and across the flat lake-like basin, where its channel has been diverted. 
A smaller lake, probably connected with this one, lies to the east, 
near Lilburn Grange. 

North of Glanton Pike is a cup-shaped hollow representing another 
ancient lake-basin. It is surrounded by sands and gravels at the foot 
of Glanton Pike and a porphyritic offshoot of the Cheviots. Within 
this is a considerable thickness of peat surrounded by a tract of peaty 
soil. This basin is drained by the Powburn. 

South of the Lilburn and just below Lilburn South Steads is another 
of these peat-covered tracts. This partakes more of the nature of 
a bog than a lake, and may have been flooded by overflow water from 
the Lilburn through a narrow channel which connects it with that 
stream. 

At the head of Kingston Dean below the village of Ilderton two 
small streams unite and enclose near their junction a triangular-shaped 
area of peat. The valley, a deep trench through Old Red Sandstone 
conglomerate, is narrow, and the lake thus formed must have been of 
very limited dimensions. 

Another lake-basin is above North Middleton, and a smaller deposit 
of peat, Cresswell Bog, opposite Haugh Head, Wooler, ‘in which 
skeletons of the red deer were found in 1830, represents an overflow 
basin of the Wooler Water. 

Conctustons.—The sections show that the sands and gravels were 
deposited under water, and the false and irregular bedding seems to 
indicate rapid deposition. The material, though to a large extent 
derived from the immediate neighbourhood, includes many rocks that 
are foreign. The source of supply of this material is readily found 
when we recognize the source of the drift on the flanks of the Cheviots 
and the moraine matter in the dry valleys with which these lower 
sands and gravels are connected. The debris is derived partly from local 
rocks and partly from foreign erratics left by ice-streams which overran 
the Cheviots from the north and south-west. The rivers together with 
water flowing through the present dry valleys fed from the glaciers 
and glacial lakes at higher altitudes, carried with them the moraine 
matter, rolling and rounding the rock fragments in their torrents, 
vet not quite obliterating all evidences of their glacial origin. ‘These 
streams flowing into the same valley at the foot of the hills must have 


458 EH. E.. L. Dixon—Titterstone Clee Hills. 


contained a tremendous volume of water, which being confined by the 


Carboniferous ranges in the east and probably dammed by ice on the 
north would fill the channel to a considerable depth. The 500 feet 
contour-line was well above the line of principal lake-deposition, and 
probably the 400 feet line or a line between this and 300 feet limited 
the margin of the lake or series of lakes. The deposits at the higher 
elevations, while continuous with those confined to the 300 feet 
contour limit, are undoubtedly composed of material less water-worn. 
The coarse gravels in the sections near Wooler and Roddam were the 
littoral deposits, while the finer material and sands of Hedgeley were 
carried into the quiet and deeper portion of the lake. 

The alluvial tracts of the Breamish and other streams, the peat and 
marl-like deposits of the recent lake-basins were formed after the 
supply of water to the mountain torrents had diminished but was still 
very much in excess of their present supply. 


EXPLANATION OF PLATE XXXY. 


Fic. 1. The Breamish Valley below Low Hedgeley. In the foreground, rising above 
the alluvial plain, are deposits of sand. The Carboniferous ridges are seen in 
the distance. 

Fic. 2. Section of sand and gravel exposed by Wooler Water near Haugh Head, 
Wooler. 


V.—Tue Gronocy or tae Tirrersrone Crier Hits.) 
By E. EH. L. Drxon, B.Se., A.R.C.S., F.G.S. 


\HE following is a preliminary account of the rocks overlying the 
Lower Old Red Sandstone of the Titterstone Clee Hills, Shrops. 
Sedimentary Series . . 4. Coal-Measures. 

3. Millstone Grit (so-called). 
2. Carboniferous Limestone Series. 
1. Upper Old Red Sandstone. 
: Intrusive rocks . é ¢ Dolerite. 

1. The Upper Old Red Sandstone, consisting largely of sandy and 
pebbly beds, is fixed in age by its fish- fauna, which has long been 
known. Its junction with the underlying Lower Old Red matls is 
perfectly sharp, and probably marks an unconformity. Upwards, 
however, the group passes into— 

2. The Carboniferous Limestone Series. The correlation of the local 
development with the Avonian of other districts has been sketched by 
Dr. Vaughan,” whose chief conclusion, that the highest recognizable 
horizon is little, if at all, higher than the upper part of the Zaphrentis 
Zone, holds good throughout the outcrops. That part of the series 
which overlies this horizon is so thin that it is difficult to believe that 
the top is much younger, even after making allowance for the fact 
that it consists of such shallow-water deposits that its rate of deposition 
must. have been conditioned by the rate of subsidence of the sea- 
bottom. This conclusion as to age is supported by the age and 
relations to the local ‘Millstone Grit’ of the top of the Carboniferous 
Limestone Series in the Forest of Dean and the Bristol area (op. cit.). 


1 Abstract of paper read at the British Association, Sheffield, September, 1910. 
2 Quart. Journ. Geol. Soc., vol. Ixi, pp. 252-4, 1905. 


~~ a e 


Grou. Mac. 1910. PLATE XXXY. 


Fic. 1. The Breamish Valley below Low Hedgeley. 
» 2. Section exposed by Wooler Water near Haugh Head, Wooler. 


a 


ve) 
7 —— ~j a a \ 
{ 
: \ 
1 
EO 


E. FE. L. Dixon—Titterstone Clee Hills. 459 


8. The ‘Millstone Grit’, which consists largely of sandstones and 
conglomerates, is undoubtedly conformable with the Carboniferous 
Limestone Series, and, as regards its base, is probably, from what has 
just been said, of Syringothyris age, and therefore much older than 
the Millstone Grit proper. Unfortunately its marine fossils, found at_ 
but one horizon, are of no zonal value, but its plants, from various 
levels, connect it, according to Dr. Kidston, with Lower Carboniferous 
rocks, not with the Millstone Grit proper. The conclusion as to the 
age of the lower part may therefore extend to the whole, and it is 
suggested that a non-committal place-name be applied to this formation 
instead of ‘ Millstone Grit’. 

4. The Coal-measures include ‘ sweet’, i.e. non-sulphurous, coals at 
several'horizons from the base upward, and have yielded, besides a fairly 
rich flora, a small marine fauna at one or two horizons. ‘The most 
important point, however, is the fact that they are not conformable 
with the ‘Millstone Grit’. Their relationship has been revealed in 
a quarry, where their basal bed, a pebbly sandstone, rests at a low 
inclination and with marked discordance on evenly-dipping beds of 
Grit ; and it affords the only satisfactory explanation of a transgression 
of the Measures across the outcrops of the Grits, which is brought 
out by 6 inch mapping. 

As the ‘ Millstone Grit’ is in part much older than the rocks of that 
name which underlie Coal-measures elsewhere, it becomes of interest 
to inquire whether the break between it and the Coal-measures on Clee 
Hill corresponds merely to the period of the Millstone Grit proper, 
or whether it includes some part of Coal-measure time also. That is, 
what is the age of the base of the Coal-measures on Clee Hill? 

A feature of these measures is the presence in them of red clays and 
green sandstones of ‘espley’ type at intervals from a few feet above 
the base upward. According to Dr. Walcot Gibson rocks of these 
characters are not known in Coal-measures of other parts of England 
and Wales from any horizon lower than the Etruria Marls or a short 
distance below. Stratigraphical evidence also suggests that the Coal- 
measures of Clee Hill commence at this level. For there is no doubt, 
as has been pointed out by Mr. Daniel Jones, but that the Clee Hill 
measures are of the same horizon as the ‘sweet coal series’ of the 
adjacent Forest of Wyre Coal-field. There, in the Kinlet district, the 
junction of this series with the overlying sandstones which yield 
the ‘sulphur coals’ was found, in the course of an extension of the 
work to that neighbourhood, to be 2 conformable one ; and therefore, 
as the sandstones have been recognized by Dr. Gibson and Mr. T. C. 
Cantrill as representing the Newcastle-under-Lyme Series, we may 
couclude that the ‘sweet coal series’ which, like the Clee Hill 
measures, include some red clays and ‘espley’-like sandstones, 
corresponds to part of the Etruria Marls. It may be added that the 
most recent Coal-measures on Clee Hill are sandstones resembling the 
Neweastle Series of the Forest of Wyre, but too thin (they form an 
outlier of a few acres extent) and poorly exposed to yield further 
evidence of their age and relationships. 

Against the conclusion that the Clee Hill measures commence with 
a representative of the Etruria Marls it may be urged that the latter 


460 A. R. Horwood—Origin of the British Trias. 


in their typical development’ yield neither coal-seams nor the flora 
and fauna which have been obtained on Clee Hill. Similar coals, 
however, occur elsewhere in England and Wales at intervals up to 
much higher horizons, though not in association with the typical 
Etruria Marl rock-facies. The objection based cn the flora is of 
greater weight, for Dr. Kidston finds that the plants are Middle 
Coal-measure forms, and therefore suggestive of a horizon lower than 
the Etruria Marls. But it may be remarked that the flora of the 
Blackband Group immediately below the Etruria Marls—the latter 
yield but rare plants—include no forms which do not occur in the 
Middle Coal-measures below.* The fauna of the marine bands is 
unfortunately of no horizonal value, though it includes a Productus 
which Dr. Vaughan finds closely resembles a form (P. aff. scabriculus, 
Mart.) abundant in the Avon section and elsewhere at the top of the 
Dibunophyllum Zone. 

Finally, a consideration of the thicknesses and characters of the 
sedimentary series and of the outcrops of dolerite shows that earth- 
movements along a N.E.-S.W. line have made themselves felt 
during— 

1. Upper Old Red Sandstone and Lower Carboniferous times. 

2. Some period between Lower Carboniferous and Coal-measure 
times. (The latter movement has resulted in the unconformity 
between the ‘Millstone Grit’ and the Coal-measures.) 

And further that the dolerite came up through several passages, 
some of which form a linear series having approximately this trend also. 


V1I.—Tase Oriein oF tHE Bririse Trias.® 


By A. R. Horwoop, 
Leicester Museum. 


S a result of an investigation covering the Midland area, and 
especially from a study of the Upper Keuper of Leicestershire, 
the author, who has been aided in this research by a grant from the 
Government Grant Committee of the Royal Society, has arrived at 
the conclusion that, in so far as Great Britain is concerned, the Trias 
was laid down under delta conditions, during which, as in the Nile 
area to-day, seolian action took place, but was not responsible for 
deposition except locally on a small scale, and following the prevalent 
wind course. 

The premises upon which this view is based are as follows :— 

1. There is a continuity of area of deposition during the Upper 
Carboniferous, Permian, and Triassic periods, and a relative homology 
between the different parts of each, i.e. the base of each is similarly 
coarser than the top, and each has a red phase ultimately. 

2. There is a gradual gradation from coarse sediments to finer from 
below upwards, as in modern (and other fossil) deltas. For instance, 
pebbles predominate in the lower phase, coarse sandstones (with 


See Dr. W. Gibson, Quart. Journ. Geol. Soc., vol. lvii, pp. 251 et sqq., 1901. 
Dr. R. Kidston, Quart. Journ. Geol. Soc., vol. lxi, p. 318, 1905. 
Abstract of paper read at the British Association, Sheffield, September, 1910. 


1 
2 
3 


A. R. Horwood—Origin of the British Trias. 461 


occasional pebbles) in the centre, and finer and finer marls succeed in 
the last phase, which becomes increasingly ferruginous, as it merges 
into the lake-phase of the delta period. 

3. The oldest member of the series, the Bunter, is acknowledged to 
be a delta formation—as Professor Bonney showed many years ago— 
and there is no evidence for the discontinuity of the agency producing 
that mode of deposition. 

4, The continuity of the Bunter and Keuper is an argument for 
the extension of delta conditions to the Keuper, some ‘basement beds’ 
being indistinguishable from the Bunter. 

5. The general evidence of an oscillation of level in early Triassic 
times and of overlapping is a proof of aqueous agency. Coupled 
together these vertical and horizontal movements are more distinctive 
of fluviatile than lacustrine or marine conditions. 

6. There is a close analogy between the contour or geographical 
configuration of the Trias (whether we consider concealed or exposed 
areas) and modern deltas, e.g. the Mississippi, with its dactyloid 
extensions beyond the head. 

7. There is a distinct analogy between the regular alternations of 
pebbles or sand and marl and seasons of torrential rains and floods or 
drought; that is to say, one sort of sediment is brought down at one 
period of the year, another at another. This may be witnessed in 
modern accumulations such as those of the Nile or Mississippi, where 
floods occur. These alternations are due to overflow of banks where 
‘skerries’ le on the hilly grounds now, just as they did when they 
were deposited. The grey marl is heavier than the red, and deposits 
are arranged as in a diffusion column. 

8. The coloration of the Trias is original; that is to say, the red 
colour, imparted by peroxide of iron, was deposited on sediments 
under water-level. But it is not continuous everywhere with the 
bedding. ‘Catenary’ bedding is thus illusory. In only one case has 
an anticlinal fold of red-coloured marl been noticed underlying a grey 
band, but, on the other hand, synclinal folds are not uncommon, as in 
catenary bedding, the grey (heavier) marl lying in the hollows. 

9. The great thickness of the Bunter pebble beds is a proof of 
a subsiding area at the opening of the Trias and of conditions suitable 
to a gradually widening and deeper delta area. 

Normally delta deposits lie at an angle of about 45 degrees with 
the river bed, but as they are deposited in a subsiding area these beds 
describe an angle of 45 degrees and become horizontal. Thus the 
absence of delta bedding (not everywhere, for it occurs in Bunter, 
Lower and Upper Keuper here and there) in the Trias is proof that it 
was deposited in a subsiding area. 

The ‘radial dip’ around submerged areas is due to the ‘angle of 
rest’ which normally produces inclined beds. The winding of the 
course of a river like the Mississippi, producing wide alluvial plains, 
would account for the Red Marl being deposited much as in a 
lacustrine area. 

10. There is evidence from analogy of the ferruginous nature of 
the Upper Coal-measures, Permian, and Trias of the delta origin of 
the red marls. 


462 A. Rh. Horwood—Origin of the British Trias. 


11. The present horizontality, the littoral or marginal dip around 
the hills (e.g. Charnwood Forest), with the south-easterly dip (as in 
the Coal-measures and Permian formation), is original. 

Trias reaches a height of 880 feet on Bardon Hill and is apparently 
in situ. Hence the elevated tracts must have originally been under 
water. 

Moreover, the following facts may be noted in connexion with 
submerged hills under the Triassic covering :— 

(1) The Trias is horizontal away from the older hills, as at Hathern, 
Sileby, ete. 

(2) It is horizontal within old gullies and fiords within the islandic 
area, as well as over ‘saddlebacks’ (anticlinal folds in older rocks, as 
at Longcliffe, Enderby), as at Groby, Swithland, Mount Sorrel. 

(3) There is an absence of faults of any magnitude. A very slight 
one affects the Rheetics at Glen Parva. ‘The older one at Bardon has 
no relation to the Trias. 

(4) It occurs filling fissures at great heights, as at Siberia Quarry, 
Bardon Hill. 

12. Only the sandstones or ‘skerries’ are rippled, not the marls, 
with ripples S.W. to N.E. in direction; that is, the ridges run N.W. 
by 8.E. generally, the force moving the wind and wave thus coming 
from the south-west. This is to be noted all round Charnwood Forest. 

13. The screes are very largely to the south-west of the sub- 
merged older rocks which they cover, and from which (as on sea-coasts 
dunes are formed with screes forming at the foot of cliffs) they are 
derived. 

14. The sandstones thin out and disappear eastward (as in the 
Lower Keuper), the marls westward, and the sandstones or skerries 
are chiefly on present hilly ground (as in the past). 

15. The surface features of the old elevated rocks are largely 
original, where not covered by the Trias. The crags of High Sharpley, 
Broombriggs, etc., are quite untouched. The structure of the older 
formation can be distinctly made out as at Hanging Rocks. Black- 
brook is only an emptied Triassic fiord. 

16. Desert conditions are confined to the marginal contact of the 
Red Marl with certain older rocks (chiefly syenites as at Croft and 
Mount Sorrel), and this occurs at the same level, indicating its merely 
local phase. Wind-polished rocks occur to the west and north of 
Castle Hill, Mount Sorrel. 

17. There is an absence of desert conditions in the surrounding 
area, 1.e. away from the old rocks. Only in one instance has an 
anticlinal fold of Red Marl, simulating a dune, been discovered, as at 
Sileby. 

18. The beds of gypsum and rock-salt are continuous in a linear 
direction, and are horizontal, which must be due to aqueous depositions 
and brought about during the greater lagoon phase at the close of the 
epoch, or the contemporary marginal lagoon phase during the early 
period, of the delta formation. ; 

19. There is a gradual gradation of the Keuper into the Rheetics 
and so into the Lias, marine conditions commencing with the Rheties. 

20. The source of the sediments is in a large measure correlated 


oe 


Professor T. G. Bonney—Glacial History of W. Europe. 463 


with that of the Bunter, which was formed by a river coming from 
North-West Scotland. 

21. There is a correspondence between the characteristics of the 
micropetrography of the Bunter, Keuper, and modern delta formations. 
The Leicestershire Trias shows signs of chemical action, the Nile delta 
of mechanical. The chemical composition of volcanic and metamorphic 
rocks locally argues a local as well as a distant source for the heavier 
minerals of the Keuper. 

22. The evidence of the flora and fauna shows that there were 
provinces, and these were so arranged as to allow for the prevalence 
of delta conditions. The climate was moist and equable. 

Finally, we conclude that there is nothing to prove that desert con- 
ditions did anything more than locally act upon the rocks mechanically, 
and to some extent chemically. They had no part whatever in the 
work of deposition; that is to say, they disintegrated the previous 
rocks (pre-Trtassic). There is positive, direct, and accumulative 
evidence to prove that the Trias as a whole (and not the Bunter only) 
was the work of rivers which had continued to bring sediment in one 
form or another from the north-west of Britain or the north more or 
less continuously, under one condition or another, from the close of 
the marine phase of Lower Carboniferous (Mountain Limestone) times. 


NOTICEHS OF MEMOTRS. 


Sse 


I.—British ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 
SHEFFIELD, 1910. Appress by the Rev. Professor T. G. Bonney, 
se.D., LL.D., F.R.S., President.? 


DO not propose, as you might naturally expect, to discuss some 
branch of petrology; though for this no place could be more 
appropriate than Sheffield, since it was the birthplace and the life- 
long home of Henry Clifton Sorby, who may truly be called the 
father of that science. This title he won when, a little more than 
sixty years ago, he began to study the structure and mineral 
composition of rocks by examining thin sections of them under the 
microscope. A rare combination of a singularly versatile and active 
intellect with accurate thought and sound judgment, shrewd in 
nature, as became a Yorkshireman, yet gentle, kindly, and unselfish, 
he was one whom his friends loved and of whom this city may well 
be proud. Sorby’s name will be kept alive among you by the 
Professorship of Geology which he has endowed in your University ; 
but, as the funds will not be available for some time, and as that 
science is so intimately connected with metallurgy, coal-mining, and 
engineering, I venture to express a hope that some of your wealthier 
citizens will provide for the temporary deficiency, and thus worthily 
commemorate one so distinguished. 
' We regret that our limited space prevents the insertion of the full text of 
Professor Bonney’s Address, Thus the statement of facts relating to the Drifts of 


Britain have been omitted, but the main arguments relating to the interpretation 
of the phenomena have been retained. 


464 Professor T. G. Bonney—Presidential Address— 


But to return. I have not selected petrology as my subject, partly 
because I think that the great attention which its more minute details 
have of late received has tended to limit rather than to broaden our 
views, while for a survey of our present position it is enough to refer 
to the suggestive and comprehensive volume published last year by 
Mr. A. Harker ;! partly, also, because the discussion of any branch of 
petrology would involve so many technicalities that I fear it would be 
found tedious by a large majority of my audience. . . . I purpose, 
then, to ask your attention this evening to some aspects of the glacial 
history of Western Europe. 

Much light will be thrown on this complex problem by 
endeavouring to ascertain what snow and ice have done in some 
region which, during the Glacial Epoch, was never submerged, and 
none better can be found for this purpose than the European Alps. 


In certain mountain regions, especially those where strong lime- 
stones, granites, and other massive rocks are dominant, the yalleys 
are often trench-like, with precipitous sides, having cirques or corries 
at their heads, and with rather wide and gently sloping floors, which 
occasionally descend in steps, the distance between these increasing 
with that from the watershed. Glaciers have unquestionably occupied 
many of these valleys, but of late years they have been supposed to 
have taken a large share in excavating them. In order to appreciate 
their action we must imagine the glens to be filled up and the district 
restored to. its former eared valor a a more or less undulating upland. 
As the mean temperature? declined snow would begin to accumulate 
in inequalities on the upper slopes. This, by melting and freezing 
would soften and corrode the underlying material, which would then 
be removed by rain and wind, gravitation, and avalanche. In course 
of time the hollow thus formed would assume more and more the 
outlines of a corrie or a cirque by eating into the hillside. With an 
increasing diameter it would be occupied, as the temperature fell, first 
by a permanent snow-field, then by the névé of a glacier. Another 
process now becomes important, that called ‘sapping’. While 
ordinary glacier-scour tends, as we are told, to produce ‘‘ sweeping 
curves and eventually a graded slope’’, ‘ sapping’ produces ‘‘ benches 
and cliffs, its action being horizontal and backwards”’, and often 
dominant over scour. The author of this hypothesis* convinced him- 
self of its truth in the Sierra Nevada. . . . Beneath the névé the 
temperature would be uniform, so its action would be protective, 
except where it set up another kind of erosion, presently to be noticed; 
but in the chasm, we are informed, there would be, at any rate for 
a considerable part of the year, a daily alternation of freezing and 
thawing. Thus the cliff would be rapidly undermined and be carried 
back into the mountain slope, so that before long the glacier would 
nestle in a shelter of its own making. Farther down the valley the 


1 The Natural History of Igneous Rocks, 1909. 

* In the remainder of this Address ‘ temperature’ is to be understood as mean 
temperature. The Fahrenheit scale is used. 

3 W. D. Johnson, Science, n.s., vol. ix, pp. 106, 112, 1899. 


Glacial History of Western Europe. 465 


moving ice would become more effective than sub-glacial streams in 
deepening its bed; but since the névé-flow is almost imperceptible 
near the head, another agency must be invoked, that of ‘ plucking’. 
The ice grips, like a forceps, any loose or projecting fragment in its 
rocky bed, wrenches that from its place, and carries it away. The 
extraction of one tooth weakens the hold of its neighbours, and thus 
the glen is deepened by ‘plucking’, while it is carried back by 
‘sapping’. Streams from melting snows on the slopes above the 
amphitheatre might have been expected to co-operate vigorously in 
making it, but of them little account seems to be taken, and we are 
even told that in some cases the winds probably prevented snow from 
resting on the rounded surface between two cirque-heads.’ As these 
receded, only a narrow neck would be left between them, which 
would be ultimately cut down into a gap or ‘col’. Thus a region of 
deep valleys with precipitous sides and heads, of sharp ridges, and of 
more or less isolated peaks is substituted for a rather monotonous, if 
lofty, highland. 

The hypothesis is ingenious, but some students of Alpine scenery 
think more proof desirable before they can accept it as an axiom. 


But even if ‘sapping and plucking’ were assigned a comparatively 
unimportant position in the cutting out of cirques and corries, it might 
still be maintained that the glaciers of the Ice Age had greatly deepened 
the valleys of mountain regions. That view is adopted by Professors 
Penck and Briickner in their work on the glaciation of the Alps,’ the 
value of which even those who cannot accept some of their conclusions 
will thankfuily admit. On one point all parties agree—that a valley 
cut by a fairly rapid stream in a durable rock is V-like in section. 

It is also agreed that a valley excavated or greatly enlarged 
by a glacier should be U-like in section. But an Alpine valley, 
especially as we approach its head, very commonly takes the following 
form. For some hundreds of feet up from the torrent it is a distinct 
V; above this the slopes become less rapid, changing, say, from 45° 
to not more than 80°, and that rather suddenly. Still higher comes 
a region of stone-strewn upland valleys and rugged crags, terminating 
in ridges and peaks of splintered rock, projecting from a mantle of ice 
and snow. The V-like part is often from 800 to 1000 feet in depth, 
and the above-named authors maintain that this, with perhaps as 
much of the more open trough above, was excavated during the 
Glacial Epoch. Thus the floor of any one of these valleys prior to 
the Ice Age must often have been at least 1800 feet above its present 
level. As a rough estimate we may fix the deepening of one of the 
larger Pennine valleys, tributary to the Rhone, to have been, during 
the Ice Age, at least 1600 feet in their lower parts. Most of them 
are now hanging valleys; the stream issuing, on the level of the main 
river, from a deep gorge. Their tributaries are rather variable in 
form ; the larger as a rule being more or less V-shaped ; the shorter, 
and especially the smaller, corresponding more with the upper part 


1 This does not appear to have occurred in the Alps. 
2 Die Alpen in Hiszeitalter, 1909. 
DECADE Y.—YOL. VII.—NO. X. 30 


466 Professor T. G. Bonney—Presidential Address— 


of the larger valleys ; but their lips generally are less deeply notched. 
Whatever may have been the cause, this rapid change in slope must 
indicate a corresponding change of action in the erosive agent. Here 
and there the apex of the V may be slightly flattened, but any 
approach to a real U is extremely rare. The retention of the more 
open form in many small, elevated recesses, from which at the present 
day but little water descends, suggests that where one of them soon 
became buried under snow, but was insignificant as a feeder of a glacier, 
erosion has been for ages almost at a standstill. 

The V-like lower portion in the section of one of the principal 
valleys, which is all that some other observers have claimed for the 
work of a glacier, cannot be ascribed to subsequent modification by 
water, because ice-worn rock can be seen in many places, not only 
high up its sides, but also down to within a yard or two of the present 
torrent. 

Thus valley after valley in the Alps seems to leave no escape from 
the following dilemma: Either a valley cut by a glacier does not 
differ in form from one made by running water, or one which has been 
excavated by the latter, if subsequently occupied, is but superficially 
modified by ice. 


Many lake-basins have been ascribed to the erosive action of glaciers. 

Since the late Sir A. Ramsay advanced this hypothesis numbers of 
lakes in various countries have been carefully investigated and the 
results published, the most recent of which is the splendid work on 
the Scottish lochs by Sir J. Murray and Mr. L. Pullar.* 
Even these latest researches have not driven me from the position 
which J have maintained from the first—namely, that while many 
tarns in corries and lakelets in other favourable situations are 
probably due to excavation by ice, as in the mountainous districts of 
Britain, in Scandinavia, or in the higher parts of the Alps, the 
difficulty of invoking this agency increases with the size of the basin— 
as, for example, in the case of Loch Maree or the Lake of Annecy—till 
it becomes insuperable. Even if Glas Llyn and Llyn Llydaw were 
the work of a glacier, the rock-basins of Gennesaret and the Dead Sea, 
still more those of the great lakes in North America and in Central 
Africa, must be assigned to other causes. 

I pass on, therefore, to mention another difficulty in this hypothesis 
—that the Alpine valleys were greatly deepened during the Glacial 
Epoch—which has not yet, I think, received sufficient attention. 
From three to four hundred thousand years have elapsed, according to 
Penck and Briickner, since the first great advance of the Alpine ice. 
One of the latest estimates of the thickness of the several geological 
formations assigns 4000 feet? to the Pleistocene and Recent, 135,000 
to the Pliocene, and 14,000 to the Miocene. If we assume the times 
of deposit to be proportional to the thicknesses, and adopt the larger 
figure for the first-named period, the duration of the Pliocene would 


1 Bathymetrical Survey of the Scottish Freshwater Lochs, by Sir J. Murray and 
Mr. L. Pullar, 1910. 
2 T have doubts whether this is not too great. 


Glacial History of Western Europe. 467 


be 1,200,000 years, and of the Miocene 1,400,000 years. To 
estimate the total vertical thickness of rock which has been removed 
from the Alps by denudation is far from easy, but I think 14,000 feet 
would be a liberal allowance, of which about one-seventh is assigned 
to the Ice Age. But during that age, according to a curve given by 
Penck and Briickner, the temperature was below its present amount 
for rather less than half (47) the time. Hence it follows that, since 
the sculpture of the Alps must have begun at least as far back as the 
Miocene period, one-seventh of the work has been done by ice in not 
quite one-fifteenth of the time, or its action must be very potent. 
Such data as are at our command make it probable that a Norway 
glacier at the present day lowers its basin by only about 
80 millimetres in 1000 years, a Greenland glacier may remove some 
421 millimetres in the same time, while the Vatnajokul in Iceland 
attains to 647 millimetres. If Alpine glaciers had been as effective 
as the last-named, they would not have removed, during their 
188,000 years of occupation of the Alpine valleys, more than 
121°6 metres, or just over 3897 feet; and as this is not half the 
amount demanded by the more moderate advocates of erosion, we 
must either ascribe an abnormal activity to the vanished Alpine 
glaciers, or admit that water was much more effective as an excavator. 

We must not forget that glaciers cannot have been important agents 
in the sculpture of the Alps during more than part of Pleistocene 
times. That sculpture probably began in the Oligocene period ; for 
rather early in the next one the great masses of conglomerate, called 
Nagelfluh, show that powerful rivers had already carved for themselves 
valleys corresponding generally with and nearly as deep as those still 
in existence. Temperature during much of the Miocene period was 
not less than 12° F. above its present average. This would place 
the snow-line at about 12,000 feet.! In that case, if we assume the 
altitudes unchanged, not a snow-field would be left between the 
Simplon and the Maloja, the glaciers of the Pennines would shrivel 
into insignificance, Monte Rosa would exchange its drapery of ice for 
little more than a tippet of frozen snow. As the temperature fell 
the white robes would steal down the mountain-sides, the glaciers 
grow, the torrents be swollen during all the warmer months, and the 
work of sculpture increase in activity. Yet with a temperature even 
6° higher than it now is, as it might well be at the beginning of the 
Pliocene period, the snow-line would be at 10,000 feet ; numbers of 
glaciers would have disappeared, and those around the J ungfrau and 
the Finster Aarhorn would be hardly more important than™ they now 
are in the Western Oberland. 

But denudation would begin so soon as the ground rose above the 
sea. Water, which cannot run off the sand exposed by the retreating 
tide without carving a miniature system of valleys, would never leave 
the nascent range intact. The Miocene Alps, even before a patch of 


1 T take the fall of temperature for a rise in altitude as 1° F. for 300 feet, or, 
when the differences in the latter are large, 3° per 1000 feet. These estimates will, 
I think, be sufficiently accurate. The ficures given by Hann (see for a discussion of 
the question, Report of Brit. Assoc., 1909, p- 93) work out to 1° F’. for each 318 feet 
of ascent (up to about 10,000 feet). 


468 Prof. T. G. Bonney—Glacial History of Western Europe. 


snow could remain through the summer months, would be carved into 
glens and valleys. Towards the end of that period the Alps were 
affected by a new set of movements, which produced their most 
marked effects in the northern zone from the Inn to the Durance. 
The Oberland rose to greater importance; Mont Blanc attained its 
primacy ; the massif of Dauphiné was probably developed. That, and 
still more the falling temperature, would increase the snow-fields, 
glaciers, and torrents. The first would be, in the main, protective ; 
the second, locally abrasive; the third, for the greater part of their 
course, erosive. No sooner had the drainage system been developed 
on both sides of the Alps than the valleys on the Italian side (unless 
we assume a very different distribution of rainfall) would work back- 
wards more rapidly than those on the northern. Cases of trespass, 
such as that recorded by the long level trough on the north side of 
the Maloja Kulm and the precipitous descent on the southern, would 
become frequent. In the Interglacial episodes—three in number, 
according to Penck and Briickner, and occupying rather more than 
half the epoch—the snow and ice would dwindle to something like 
its present amount, so that the water would resume its work. Thus 
I think it far more probable that the V-lke portions of the Alpine 
valleys were in the main excavated during Pliocene ages, their upper 
and more open parts being largely the results of Miocene and yet 
earlier sculpture. 

During the great advances of the ice, four in number, according to 
Penck and Briickner,! when the Rhone glacier covered the lowlands 
of Vaud and Geneva, welling on one occasion over the gaps in the 
Jura, and leaving its erratics in the neighbourhood of Lyons, it ought 
to have given signs of its erosive no less than of its transporting 
power. But what are the facts? In these lowlands we can see 
where the ice has passed over the Molasse (a Miocene sandstone) ; but 
here, instead of having crushed, torn, and uprooted the comparatively 
soft rock, it has produced hardly any effect. The huge glacier from 
the Linth Valley crept for not a few miles over a floor of stratified 
gravels, on which, some 8 miles below Zurich, one of its moraines, 
formed during the last retreat, can be seen resting, without having 
produced more than a slight superficial disturbance. We are asked to 
credit glaciers with the erosion of deep valleys and the excavation of 
great lakes, and yet, wherever we pass from hypotheses to facts, we 
find them to have been singularly inefficient workmen! 

I have dwelt at considerable, some may think undue, length on the 
Alps, because we are sure that this region from before the close of 
the Miocene period has been above the sea-level. It accordingly 
demonstrates what effects ice can produce when working on land. 

In America alsoto which I must now make only a passing reference, 
great ice-sheets formerly existed: one occupying the district west of 
the Rocky Mountains, another spreading from that on the north-west 
of Hudson’s Bay, and a third from the Laurentian . hill-country. 
These two became confluent, and their united ice-flow covered the 
region of the Great Lakes, halting near the eastern coast a little south 


1 On the exact number I have not had the opportunity of forming an opinion. 


= 


Notices of Memoirs—Papers at British Association. 469 


of New York, but in Ohio, Indiana, and Illinois occasionally leaving 
moraines only a little north of the 39th parallel of latitude. Of these 
relics my first-hand knowledge is very small, but the admirably 
illustrated reports and other writings of American geologists indicate 
that, if we make due allowance for the differences in environment, the 
tills and associated deposits on their continent are similar in character 
to those of the Alps. 

In our own country and in corresponding parts of Northern Europe 
we must take into account the possible co-operation of the sea. In 
these, however, geologists agree that, for at least a portion of the Ice 
Age, glaciers occupied the mountain districts. Here ice-worn rocks, 
moraines and perched blocks, tarns in corries, and perhaps lakelets in 
valleys, demonstrate the former presence of a mantle of snow and ice. 
Glaciers radiated outwards from more than one focus in Ireland, Scot- 
land, the English Lake District, and Wales, and trespassed, at the 
time of their greatest development, upon the adjacent lowlands. 
They are generally believed to have advanced and retreated more than 
once, and their movements have been correlated by Professor J. Geikie 
with those already mentioned in the Alps. Into that very difficult 
question I must not enter ; for my present purpose it is enough to say 
that in early Pleistocene times glaciers undoubtedly existed in the 
mountain districts of Britain and even formed piedmont ice-sheets on 
the lowlands. On the west side of England, smoothed and striated 
rocks have been observed near Liverpool, which can hardly be due to 
the movements of shore-ice. . . . On the eastern side of England 
similar markings have been found down to the coast of Durham, but 
a more southern extension of land ice cannot be taken for granted. 
In this direction, however, so far as the tidal valley of the Thames, 
and in corresponding parts of the central and western lowlands, 
certain deposits occur which, though to a great extent of glacial 
origin, are in many respects different from those left by land ice in the 
Alpine regions and in Northern America. 

They present us with problems the nature of which may be inferred 
from a brief statement of the facts.! 


(To be concluded in our next Number.) 


II.—Bririsa AssocratTion FoR THE ADVANCEMENT OF ScrtencE, E1gHTIETH 
AnnuaL MEETING, HELD AT SHEFFIELD, SEPTEMBER 1-7, 1910. 
List oF Tirtes oF Papers READ IN SeEction C (GEOLOGY) AND IN 
OTHER SECTIONS BEARING UPON GEOLOGY. 


Presidential Address by Dr. A. P. Coleman, F.R.S. 

Cosmo Johns.—The Yoredale Series and its equivalents elsewhere. 

Dr. J. &. Marr, .RS., & W. G, Fearnsides, U.A.—The Paleozoic 
Rocks of Cautley (Sedbergh). 

Miss G. R. Watney & Miss EL. G. Welch.—The Graptolitic Zones of 
the Salopian Rocks of the Cautley Area (Sedbergh). 

Professor J. Joly, D.Sc., F.R.S.—Pleochroic Halos. 


1 See footnote on p. 463, at the commencement of the President’s Address, 


470 Notices of Memoirs—Papers at British Association. 


Dr. J. D. Faleoner.—Outlines of the Geology of Northern Nigeria. 

Dr. F. H. Hatch.—-Yhe Geology of Natal. 

Cosmo Johns.—The Geology of the Sheffield District. 

Professor A. McWilliam.—The Metallurgical Industries in relation to 
the Rocks of the District. 

T. Sheppard.—The Humber during the Human Period. 

Dr. Tempest Anderson.—Matavanu, a new Volcano in Savaii (German 
Samoa). 

Rev. EL. C. Spicer, M.A.—On present Trias Conditions in Australia. 

Dr. Wm. H. Hobbs.—Some considerations concerning the Alimentation 
and the Losses of existing Continental Glaciers. 

Dr. J. Milne, F.R.S.—Seismological Report. 

Mrs. M. U. Ogilvie Gordon, D.Sc.—Thrust Masses in the Western 
District of the Dolomites. 

Professor J. W. Gregory, D.Sc., F.A.S.—On the Geology of Cyrenaica. 

Marmaduke Odling.—An Undescribed Fossil from the Chipping Norton 
Limestone. 

Professor Edward Hull, LL.D., F.R.S.—The Glacial Rocks of 
Ambleside. 

Dr. C. H. Lees, F.R.S.—Mountain Temperatures and Radium. 

John Parkinson.—Notes on the Geology of the Gold Coast. 

A. D. Hall, F.RS., & Dr. #. J. Russell_—The Objects and Scope of 
Soil Surveys. 

L. F. Newman.—Drift Soils of Norfolk. 

C. ZT. Cimingham.—TVhe Teart Land of Somerset. 

Sir T. H. Holland, F.R.S.—TYhe Cause of Gravity Variations in 
Northern India. 

Discussion on the concealed Coal-field of Notts, Derbyshire, and York- 
shire. Opened by Professor P. F. Kendall, U.Sc., & Dr. Walcot 
Gibson. 

H. Culpin.—The Marine Bands in the Coal- measures of South 
Yorkshire. 

W. H. Dyson.—The Maltby Deep Boring. 

Miss Ml. C. Stopes, D.Sc., Ph. D.—Structural Petrifactions from the 
Mesozoic, and their bearing on Fossil Plant Impressions. 

Dr. L. Moysey.—On some Rare Fossils from the Derbyshire and Notts 
Coal-field. 

A, k. Horwood.—The Origin of the British Trias. 

Rev. A. Irving, D.Sc., B.A.—On a Buried Tertiary Valley through 
the Mercian Chalk Range, and its later ‘‘ Rubble Drift’, etc. 

Cosmo Johns. — The Geological Significance of the Nickel - Iron 
Meteorites. 

Ernest Dixon, B.Se.—The Geology of the Titterstone Clee Hills. 

Reports on— 

Erratic Blocks. 

Crystalline Rocks of Anglesey. 

Faunal Succession in the Carboniferous Limestone. 
Critical Sections in the Paleeozoic Rocks. 
Charnwood Rocks. 

Rocks of Glensaul. 

Correlation and Age of South African Strata. 


Notices of Memoirs— Concealed Coal-measures. 471 


Geological Photographs. 

Fossil Flora and Fauna of the Midland Coal-fields. 

Topographical and Geological Terms used locally in South Africa. 
Dr. A. Irving, D.Sc., B.A.—The pre-Oceanic Stage of Planetary 

Development. 


List of Titles of papers read in other Sections bearing upon Geology :— 
Section A.—Puysicat Scrence. 
Sir Norman Lockyer, K.C.B.—Chemistry of the Stars. 


Section E.— GroeraPuHy. 


0. G. 8S. Crawford.—A Regional Survey of the Andoyer District. 
J. Cossar.—A Regional Survey of Midlothian. 

H. Brodrick.—The Underground Waters of the Castleton District. 
Dr. 0. A. Hill.—Further Exploration in the Mitchelstown Cave. 


Section .H.— AnTHROPOLOGY. 


Presidential Address by W. Crooke, B.A. 

A, WM. Woodward § H. A. Ormerod.—A Primitive Site in South-West 
Asia Minor, 

A.J. B. Wace & M. S. Thompson.—Excavations in Thessaly. 

Professor R. C. Bosanquet.—Vhe work of the Liverpool Committee for 
Excavation and Research in Wales and the Marches. 

Professor W. M. Flinders Petrie—The Excavations at Memphis. 

Dr. G. G. Seligmann.—On a Neolithic Site in the Southern Sudan. 

Dr. 7, Ashby.—Excavations at Hagiar Kim and Mnaidra, Malta. 

H, D, Acland.—Prehistoric Monuments in the Scilly Isles. 

Alexander Sutherland.—On the Excavation of the Broch of Cogle, 
Watten, Caithness. 

G. Clinch.—Unexplored Fields in British Archeology. 

Report of a Committee to investigate the Lake Villages in the neigh- 
bourhood of Glastonbury. 

Report of a Committee to ascertain the Age of Stone Circles. 

Rev. Dr. Irving.—On a Prehistoric Horse found at Bishop’s Stortford. 


* Section K.—Borany. 

Professor F. O. Bower. —Semi-popular lecture on Sand-dunes and 
‘Golf-links. 

Professor F. O. Bower.—On two Synthetic Genera of Filicales. 

Professor D. T. Gwynne-Vaughan.—On the Fossil genus Tempskya. 

Dr. M. C. Stopes.—Further Observations on the Fossil Flower. 


AgsTRacTs oF Papers READ IN Section C (Gxoroey) at THE Mererine 
oF THE British AssociaTION FOR THE ADVANCEMENT OF SCIENCE, 
SHEFFIELD, SEPTEMBER 1, 1910. 


I1J.—Tue Coat-MEASURES OF THE ConcEALED YoRKSHIRE, NorrincHAM- 
SHIRE, AND DerpysHrre CoaL-Fietp. By Watcor Grsson, D.Sc. 
()* the map accompanying Mr. Currer Brigg’s Report on District D 

in the Final Report of the Royal Commission on Coal Supplies 
for 1905 a triangular area having its apex at the Haxey (South Carr) 


472 Notices of Memoirs—Concealed Coal-measures. 


boring is marked off as the proved extent of the concealed coal-field. 
The area thus defined amounts to about 460 square miles. To this, 
as the result of information obtained from several borings for coal 
completed since 1905, there can be added about 200 square miles 
situated north-east of Haxey and about 200 square miles lying south- 
east of Haxey. Much information has also been collected in the 
proved coal-field. The new material, so far as it relates to the Coal- 
measures, may be considered under (1) shape of the Paleozoic floor, 
(2) character of the measures, (3) the workable seams that are likely 
to occur within 4000 feet depth, and (4) their probable extension 
beyond the limits considered as proved in the Report of 1905. 

1. Paleozoic Floor.—Between the outcrop of the Magnesian Lime- 
stone and the River Trent, north of Nottingham, the Permian rests on 
a uniform plain with a slope not exceeding two degrees and having 
a general direction to the east or a little north of east. Over the 
faulted area, south of Nottingham, the uniformity of slope has been 
broken; but outside the faulted belt the same even surface is 
maintained between Ruddington, Edwalton, and Owthorpe. 

2. Character of the Measures.—The Barlow (Selby) boring in the 
north, the Thorne boring in the east, and that of Owthorpe in the 
south show that the Coal-measures immediately beneath the newer 
formations belong to an horizon several hundred feet above the Top 
Hard or Barnsley Coal, which is a high and most valuable seam in the 
coal-field. In these measures a marine band (20 to 50 feet thick) lies 
between 520 feet (Oxton boring) and 629 feet (Mansfield Colliery) 
above the Top Hard Coal in Nottinghamshire, and, as ascertained by 
Mr. Culpin at Brodsworth and Bentley and by Mr. Dyson at Maltby, 
between 670 and,705 feet above the Barnsley Coal in Yorkshire. 
The fauna, exclusively marine, is represented by fifty species 
distributed among thirty-seven genera. Many of the forms occur in 
the shales below the Millstone Grits, and a few represent survivors 
from the Carboniferous Limestone. The persistence, thickness, and 
fauna of the bed indicate a general and a fairly prolonged incursion 
of the open sea during late Middle Coal-measures. Minor incursions 
are represented by a few thin beds occurring above and below this 
horizon in Nottinghamshire and Yorkshire. The thickness of the 
measures as a whole increases to the north and diminishes to the east. 

3. The Workable Seams.—All the borings and sinkings strike Coal- 
measures above the chief marine bed; but, except at Oxton and 
Maltby, both situated in the proved coal-field, the Upper Coal-measures 
have been completely removed by pre-Permian denudation. The 
seams above the Top Hard Coal and Barnsley Coal are irregular in 
their occurrence and of uncertain quality. In the Doncaster and 
Thorne area the Dunsil Coal 50 feet below the Barnsley bed appears 
to be a valuable seam, but it deteriorates south of Doncaster. Most 
of the lower coals over the recently proved extension of the coal-field 
lie beyond the limit of profitable working. The future resources of 
the coal-field therefore mainly depend upon the thickness, quality, and 
depth of the Top Hard or Barnsley Coal. 

4. Hxtension.—As a result of the explorations made since the Report 
of 1905 the proved limit of the concealed coal-field may with some 


Notices of Memoirs—Graptolite Zones. 473 


confidence be extended to a line joining Selby, Thorne, Haxey, and 
Owthorpe, but the quality and thickness of the coal cannot be foretold. 
There is no conclusive evidence to show whether, north of Thorne, 
the Barnsley Coal will take on the inferior character which it assumes 
north-east and east of Wakefield under the name of the Warren House 
Coal, and whether the thinning out of the Top Hard Coal observable 
in some of the collieries south of Mansfield will continue to the east. 

A further extension north of the Ouse, east of the Trent, and south- 
east of Owthorpe is probable, but it is important to bear in mind how 
much there must be of conjecture in any conclusions arrived at from 
the slender evidence at present available. 


TV.—Tue Grarroniric Zones oF ton Satopran Rocks oF THE CAUTLEY 
AREA NEAR SepBeRGH, YorKsHrrE. By Miss G. R. Warnzy and 
Miss EK. G. Wetcu. 


EK haye obtained the following zones in the Ludlow Rocks in 
descending order :— 


1. Monograptus leintwardinensis (Hopk.) : . Lower Bannisdale Slates. 
2. Monograptus Nilssoni (Barr.) . : . 5 ' aes pone Ae 
3. Monograptus vulgaris (Wood) . : : - M. Coldwell Beds. 


In the Wenlock the following zones have been found in descending 
order :— 
( L. Coldwell Beds. 


1. Cyrtograptus Lundgrent (Tullb.) | Brathay Flags 


Cyrtograptus Linnarssoni (Lapw.) \ ‘ ; 
= { Cyrtograptus symmetricus (Elles) : ~ Brathay Flags. 
3. Monograptus riccartonensis (Lapw.) . : . Brathay Flags. 
4. Cyrtograptus Murchisoni (Carr) . 5 . Brathay Flags. 


These zones are comparable with those discovered by Miss Elles! 
and Mrs. Shakespear’ in Wales and the Welsh Borderland!; though 
we have not yet succeeded in finding all the zones which they record 
we hope shortly to establish them in this area. 


V.—SrrvcruraL PerriractIons FrRoM THE MesozoIc, AND THEIR 
BEARING ON Fossiz Prant Impresstons. By Miss M. C. Sropxs, 
DScee bh... Fels. 


/Y\HE paper dealt with the importance of the structural petrifactions 

in the Carboniferous, e.g. exposure of the true nature of so 
many supposed ‘ferns’; with the need of similar petrifactions from 
beds of Mesozoic age; and the danger of inferences drawn from plant 
impressions, e.g. untrustworthiness of many of Heer’s and Ettings- 
hausen’s systematic determinations. 

The discovery of true petrifactions in the Cretaceous, the nature of 
the flora contained in the nodules, and unusual points in its composition 
were considered. Special illustrations of its interest are: Yezonia, a 
new type of which the external appearance gives no clue to its nature ; 
the discovery of the first-known flower with its anatomy petrified; 
and of the internal anatomy of the leaves of Wilssonia, long well known 
as impressions. 

1 Q.J.G.S., 1900. 


474 Notices of Memoirs—Lower Paleozoic Rocks. 


VI.—Nores on tHe Lower Patmozorc Rocks or rae Cavriey Disrricr, 
SeppercH, Yorks. By J. E. Marr, Sc.D., F.R.S., and W. G. 
Frarnsipes, M.A., F.G.S. 


HE general succession is well known. The following additions 
to our knowledge of the various divisions have been recently 
obtained by us :-— 

Salopian.—Divisible into Lower Ludlow Rocks (Bannisdale Slates, 
Coniston Grits, and Coldwell Beds) above, and Wenlock Rocks 
(Brathay Flags) below. The calcareous gritty flags with Phacops 
obtusicaudatus are found here at the base of the Coldwell Beds, and 
form a ready line of separation between the Ludlow and Wenlock 
graptolitiferous strata. The Salopian graptolitic zones are being 
worked out by Miss G. R. Watney and Miss E. G. Welch. 

Valentian.—The succession as described by one of us with the late 
Professor Nicholson was incomplete. We have now found a section 
in Watley Gill which nearly completes the sequence. In that beck 
the Ionograptus argenteus, I. fimbriatus, and Dimorphograptus zones 
of the Skelgill Beds are found with their intercalated Trilobite beds, 
the higher graptolitic zones being absent owing to a fault which 
repeats the Dimorphograptus beds. The argenteus zone contains the 
type fossil and its usual associates, and exhibits the ‘ green streak’ 
seen in the Lake District and in North Wales. 

A shgillian.—The Ashgill Shales have long been known here. The 
basal Staurocephalus Limestone appears to be represented by a greyish 
argillaceous limestone in Taith’s Gill, which succeeds the Caradocian 
rocks with perfect conformity, and yields abundance of Remoplewmdes 
radians and other fossils; also by a similar limestone in the same 
position in Backside Beck, with badly preserved Trilobites, ete. 

Caradocian.—Black caleareous shales with their argillaceous lime- 
stones containing a very rich Caradocian fauna, recalling that of the 
Trinucleus Shales of Sweden. The fauna is being worked at and 
separated from that of the Ashgillian, Beds. 


VII.—Own some Rare Fosstts From THE DERBYSHIRE AND NoTTinG 
HAMSHIRE Coat-FIELD. By L. Moyssy, B.A., M.B., B.C., F.G.S. 


N the temporary museum in connexion with this section there will 
be found a collection of fossils illustrating some of the rarer forms 

of the Coal-measure fauna obtained during the last eight years from 
this district. From these it has been thought desirable to select some, 
mainly fragmentary specimens, for more detailed description, in the 
hope that they may be of assistance in the identification of other 
more perfect specimens, should such be obtained, and that a discussion 
on their many perplexing features may lead to a more definite idea as 
to their affinities. : 
Specimen 1, from Shipley, near Ilkeston, Derbyshire. These 
minute bodies, about 3mm. long, are evidently the valves of the 
carapace of a Phyllopod. A similar fossil was described by Lea! from 
Pennsylvania under the name of Cypricardia leidyi. Professor T. 


1 Proc. Acad. Nat. Sc. Philadelphia, vol. vii, pt. iv, p. 341, 1855. 


a 


Reviews—British Museum Book Catalogue. 475 


Rupert Jones! gave it the name of Leava leidy?, and described two 
varieties, one Z. letdyi var. Williamsoniana, from Ardwick, near 
Manchester, and the other Z. leidyi var. Salteriana, from Cottage 
Row, Crail, Fifeshire. The present example agrees fairly closely 
with the Fifeshire specimen; but, on the whole, it seems best to 
create a new species for it, Zeava trigonoides, sp. noy., rather than 
risk confusion by adding a varietal appellation. 

Specimen 2, from Shipley, is of interest, owing to the great difficulty 
of its interpretation. Possibly the best explanation is that it is the 
glabellar region of a Prestwichia. The presence o: two minute 
erescentic dots, one on each side of the median line, is in favour of 
this theory, on the assumption that they are the larval eyes of the 
animal. Dr. Henry Woodward, however, who has examined this 
specimen, is very doubtful as to its limuloid origin. 

Specimen 8, from the Kilburn Coal, Trowell Colliery, Notts. The 
curious feature in this specimen is the presence of crescentic openings 
on each segment similar to the ‘stigmata’ found in scorpions and 
other Arachnids, suggesting that it may be a fragment of an air- 
breathing animal. 

Specimen 4, from Shipley, is probably one of the first abdominal 
segments of Hoscorpius sp., two specimens of which genus have been 
found in this district—one from near Chesterfield, and another, at 
present undescribed, found by the author in the Digby Claypit, 
Kimberley, Notts. 

Specimen 5, from Brindsley, Notts, is a single segment of «an 
Arthropod, and possibly referable to Hurypterus. 

Specimen 6, from Shipley, is the wing of an insect probably belonging 
to the order Paleeodictyoptera of Scudder. 

Specimens 7 and 8, also from Shipley, are a fragment of a much 
smaller insect’s wing, which, in its incomplete state, would be 
impossible to assign to any definite order. 

Insects’ wings are very uncommon in the Coal-measures of this 
district, only one having been found near Chesterfield, and described 
by 8S. H. Scudder? under the name Archeoptilus ingens. 


RAV LEws- 


T.—A Great Catatocur or Booxs on tHE Natural SCIENCES. 


Brittse Museum (Narurat Hisrory).—Caratoguge oF THE Books, 
Manuscriets, Mars, anp Drawines IN THE British Museum 
(Naturat History). Vol. III. L-O. By Brernarp Barwa 
Woopwarp. 4to. London, 1910. pp. 10389-1494. Price £1 
per volume. 

N September, 1903, we had the pleasure to announce the publication 
of the first volume of this work from A—D. Volume II (E-K) 
followed in 1904, and progress since then has been seriously hampered 


1 Mon. Pal. Soc., 1862, Appendix, p. 115, pl. i, fig. 21, ete. 
2 §. H. Scudder, ‘‘ Haxapod Insects of Great Britain’?: Mem. Boston Nat. Hist. 
Soe., vol. ii, pp. 217-18, 1873-94. 


. 


476 Reviews—Earthquake in California. 


by the great increase in current library work common to all libraries. 
We are, however, thankful to receive Volume III, for now we are 
well past the middle of the work, and the whole cannot be much 
longer delayed. ‘The present volume is even better than its pre- 
decessors, and in many points is better than anything of the kind that 
has been done before. The same wealth of bibliographic detail is 
observed whenever necessary, as may be seen under C. F. P. Martius, 
Francois Levaillant, and Martin Lister for example; the same 
intelugent and uniform rendering of Russian names is employed ; 
and careful attention is called to many bibliographic subtilties, 
so puzzling to the lay mind. Full details of books of travel 
are given, as for instance under Middendorff, where the separate 
papers are properly listed out and the dates given, and exact dates 
are furnished (we believe for the first time) of such troublesome 
books as the Naturalist’s Library, which was reprinted again and 
again as the supply ran short. That part of the Catalogue dealing 
with Linneus is one of which any librarian might be proud. It is 
a tour de force, and was, we believe, issued specially as a separate for 
the celebration in honour of the great naturalist in Stockholm three 
ears ago. 

‘ A brief Preface by Mr. Fletcher reminds us that Mr. Woodward 
has continued to profit by the assistance of his colleagues on the staff, 
his valued attendant Mr. Hadrill, his clerical assistant Mrs. Wilson, 
and other friends, but the inception and carrying through of this 
invaluable book is due to himself, and those who use it and recognize 
its utility can hardly find words to properly express their thanks to 
him. What the value of a Catalogue like this must be to those 
smaller libraries who can never hope to amass such a collection or to 
get access to such reference books whereby such a collection can be 
properly catalogued we do not know; all we hope is that the Trustees 
of the British Museum haying issued such a book, librarians will avail 
themselves of the privilege and secure it. 


I].—Tue Harraqevake or 1872 In tHE Owens Vatiry, CALIFORNIA. 
By Professor W. H. Hosss. Beitrage zur Geophysik, vol. x, 
pp- 852-85, 1910. 

f{\HE Owens Valley earthquake of March 26, 1872, is one of the 

greatest and most interesting of Californian earthquakes, and, in 
writing its history, Professor Hobbs has supplied a long-felt want, 
and suppled it well. ‘The principal sources of his information are 

Whitney’s almost inaccessible report published in 1872, from which 

he makes several interesting extracts, and the valuable maps and 

photographs of the fault-scarps obtained by Mr. Willard D. Johnson 
during his survey of the district in 1907. Though the natural 
tendency of fault-scarps formed during earthquakes is to lose their 
sharpness and eventually to become effaced, many of them are still 
recognizable. Those along which movements took place in 1872 run 
along the west side of the Owens Valley at the foot of the Alabama 

Hills for a total distance of about forty miles. For considerable 

distances, generally one or two miles, the individual scarps maintain 


Brief Notices. 477 


a nearly constant direction, but at intervals they are subject to abrupt 
changes of direction so as to form a series of zigzags with sharp 
elbows. In places the faults run in parallel lines, the ends over- 
lapping for short distances. All scarps, which are not much worn 
away, are steeply inclined and appear to be the continuations of nearly 
vertical faults. The highest measured vertical displacement along any 
scarp is 23 feet. Abrupt variations, and even reversal in throw are, 
however, occasionally seen. Horizontal displacements were also 
observed, though the evidence of such displacements is now almost 
obliterated. One of 15 feet towards the north was measured by 
Gilbert eleven years after the earthquake, and another of 9 feet was 
photographed by Mr. Johnson. 
CD: 


Il1.—Brier Notices. 


1. ‘Tar Sanp-Dunzs or tHE Lisyan Desrrtr’’ are described and 
illustrated by Mr. H. J. Llewellyn Beadnell (Geograph. Journ., Apvril, 
1910). In his opinion the material has been derived from the 
arenaceous formations of post-Middle Eocene age that lie to the north. 
The dunes consist mainly of silica, but in places they contain rather 
more than 7 per cent. of limestone granules. As the author remarks, 
**In some localities extensive and prosperous settlements have been 
overwhelmed and blotted out of existence, while in others the sand 
and dust-laden winds have been of positive benefit to the inhabitants. 
In the south part of the oasis of Kharga, for instance, broad terraces 
of cultivable loam have been gradually built up in the neighbourhood 
of the wells, the deposition of the wind-borne material being encouraged 
on account of its valuable fertilizing properties.’’ The subject is 
therefore of considerable economic importance as well as scientific 
interest. The author’s observations show that the dunes progress 
steadily southwards at an average rate of 15 or 16 metres a year. 

2. LANDSLIDES In THE San Juan Mountains, Cotorapo, form the 
subject of a memoir by Mr. Ernest Howe (Professional Paper 67, 
U.S. Geol. Survey, Washington, 1907). It is well illustrated, and 
contains much information of general interest and importance. 

The topography of the San Juan Mountains is described as ‘‘ that of 
a dissected and glaciated plateau of more or less horizontally bedded 
voleanic rocks resting upon a foundation of sedimentary rocks”’. The 
oldest rocks, which are pre-Cambrian, are covered unconformably by 
various Paleozoic and Mesozoic formations, and by the Telluride 
conglomerate that is perhaps of Eocene age. The Tertiary volcanic 
rocks, with an aggregate thickness of ‘‘ many thousands of feet’’ in 
the central part of the mountains, rest on the Telluride conglomerate 
or on a floor of older rocks, the dip of which is southerly, westerly, or 
northerly. Various forms of rock-falls, landslips, and soil-slips are 
described, all the rocks being lable to be affected. The superficial 
movements of the ground comprise earth-slides or soil-slips, mud-flows, 
and talus slumps. Other movements,’ though less common, are due 
to movement along bedding-planes in the direction of the dip. The 
primary jointing and secondary shattering of the rocks has led to 


478 Brief Notices. 


rock-falls. Further, the oversteepness of the valley-walls that existed 
in a great many places after the final retreat of the ice of the Glacial 
epoch has had a potent influence on landslides. Earthquakes in some 
instances have been the immediate cause of the breaking away of 
rock-masses. 

The author draws particular attention to ‘rock streams’, which 
have certain features in common, both with landslides and ordinary 
talus. In general appearance these accumulations resemble long 
tongues or lobes of talus stretching far out from the base of the cliffs 
from which they were derived, over the nearly level or gently sloping 
floors of the glacial cirques. The deposits are usually bounded by 
a sharply defined steep front; their surfaces are marked by irregular 
hummocks or wave-like ridges; and the material consists of angular 
blocks of rock, averaging about one foot in diameter, with finer and 
coarser material. They characterize tracts where the rocks are much 
shattered. Ice and snow may have influenced the formation of these 
rock-streams, but the author ‘‘ believes that they are strictly land- 
slides and owe their present form entirely to the nature of their fall 
and to the character or physical condition of the rocks involved in the 
fall”. They appear in the main to be due to the rapid slipping of 
surface material. 

3. Tue JournaL oF Grotogy (Chicago) maintains its reputation for 
original essays on subjects of wide interest and importance. In the 
number for May—June, 1910, Mr. E. 8S. Bastin writes on the ‘‘ Origin 
of the Pegmatites of Maine”’, and concludes that the broader field- 
relations suggest that the large areas characterized by pegmatite 
intrusions constitute in reality the roofs overlaying granite batholiths. 
Mr. 8. R. Capps, jun., deals with the ‘‘ Rock Glaciers in Alaska”. 
These are formed of angular talus and occupy cirques, or the bottoms 
of cirque-like valleys, that were excavated at the time of the maximum 
glaciation of the region. Small glaciers still exist at the heads of 
some of the valleys, but in most cases conditions for ordinary glacial 
activity have ceased, the winter’s snows having all melted away 
during the summer. The base of the talus, however, has been filled 
with interstitial ice, and the movement of the mass in a glacier-like 
way has continued. In some respects these ‘rock glaciers’ are allied 
to the ‘rock streams’ described by Mr. Ernest Howe as essentially 
due to surface landslides. In the number for July—August, Mr. H. M. 
Eakin contributes an article on ‘‘ The Influence of the Earth’s Rotation 
upon the Lateral Erosion of Streams’; and Mr. R. E. Hore writes 
‘©On the Glacial Origin of Huronian Rocks of Nipissing, Ontario ’’. 

4, American PurnosopHtcaL Socrrty.—In the Proceedings for January 
to April, 1910 (vol. xlix, pp. 57-129) there is an important memoir 
by Mr. W. H. Hobbs on ‘‘ Characteristics of the Inland Ice of the 
Arctic Regions”. The author contrasts the physical conditions of the 
North and South Polar areas, and the differences between mountain 
and continental glaciers. The ice-cap glacier, while of smaller 
dimensions than the true inland ice or the continental glacier, is 
regarded as distinctly allied with this type, having few affinities with 
mountain glaciers. Descriptions are given of the ice-cap glaciers of 
Norway and Iceland, of the ice-covered archipelago of Franz Josef 


Correspondence—A. C. G. Cameron. 479 


Land, of the inland ice of Spitzbergen, and of the continental glacier 
of Greenland. The englacial and subglacial drainage, the marginal 
lakes, the fresh water or ‘submarine wells’ in fiord heads, and the 
discharge of bergs, are likewise described; and the subject is well 
illustrated by diagrams and pictorial views. : 

In the number for July, 1910, Mr. W. J. Sinclair records the 
discovery of bones of Paramylodon in the Pleistocene asphalt deposits 
near Los Angeles. Mr. T. J. J. See gives the ‘‘ Results of Recent 
Researches in Cesmical Evolution”, believing that the planets were 
developed in the solar nebula, and that our moon was originally 
a planet which became a satellite, but was never part of the terrestrial 
globe. 


5. WE have received a copy of the sixth edition of the useful Zubles 
Jor the Determination of Minerals by Physical Properties, by Dr. Persifor 
Frazer and Professor A. P. Brown. (London and Philadelphia, J. B. 
Lippincott Co., 1919.) 


CORRESPONDENCE. 


YORKSHIRE GEOLOGISTS AND EDITORS. 
Srr,— Would the Hull Geological Society kindly inform us of what 


possible use it is to publish generic names under the combinations of 
letters quoted below ?- 


Psil. Cor. Ast. Kchi. 
Cal. Agas. Nicro. Der. 
Schlot. Arn. Ambly. Polym. 
Ver. Arie. Oxyn. Upt. 


We doubt whether one person in a hundred has the remotest idea 
what they mean. It is impossible for the Recorder to waste his time 
looking them up, and work presented in such a way can only be 
disregarded. 

While in the critical mood we should also like to ask whether the 
table on the distribution of Belemnites in the Lias is the result of 
personal collecting or of collation of printed data? If the latter, it is 
of little value. If the former, it would be interesting to know who is 
the authority for the determination of Simpson’s species. What really 
valuable work Yorkshire geologists might do if some competent man 
would go and draw and describe Simpson’s types in the same way as 
Mr. Buckman is doing for the Ammonites ! 

LECORDER. 


LYME REGIS CHURCH. 


Sir,—The ancient and historic church of St. Michael, Lyme Regis, 
which is a good example of fifteenth century Perpendicular Gothic, is 
in danger owing to the encroachment of the sea. The cliffs of the 
district are of Blue Lias and crumble readily. Many can remember 
when two fields stretched between the churchyard and the edge of the 


480 Miscellaneous. 


cliff; but to-day not only have these disappeared, but a portion of the 
churchyard has gone also, and the church itself is now only 80 feet 
from the cliff-edge. 

Mr. Francis Fox, of Sir Douglas Fox & Partners, 56 Moorgate 
Street, has made a gratuitous report out of goodwill towards a parish 
which is by no means wealthy. He explains that the trouble is due 
to loss of material through infiltration of the water, as the graveyard 
for a depth of 10 to 15 feet is composed. of light porous material. 
He proposes a system of rubble drains, and at the foot of the cliff 
a reinforced concrete wall to prevent further erosion of the lime- 
stone beds. 

The work will cost £2000, and a local committee has been formed. 
Already about £1200 has been received. Donations may be sent to 
the Vicar, the Rev. W. Jacob, or to Mr. J. E. Hill, Wilts and Dorset 
Bank, Lyme Regis. 

A. C. G. Cameron. 


Lyme Rezcis. 


MISCHILUANHOUS. 


Tue Prenistoric Lake-DWELLiInes, GLAstonBury.—A full description 
of the recent excavations at the Glastonbury prehistoric lake-village 
is to be published by the Glastonbury Antiquarian Society. It is 
being prepared by Mr. Arthur Bulleid, the discoverer of the site, and 
Mr. Harold St. George Gray. Dr. Robert Munro is contributing an 
introductory chapter, and amongst other contributors will be Dr. Boyd 
Dawkins, Dr. C. W. Andrews, and Mr. Clement Reid. 

A CrytenartAn Gerozocist.— Mr. John Randall, of Madeley, 
Shropshire, has this year celebrated his 100th birthday, haying been 
born at Ladywood, Broseley, on September 1, 1810. Mr. Randall 
(with George E. Roberts) read before the Geological Society in 
January, 1868, a paper ‘‘On the Upper Silurian Passage-beds at 
Linley, Salop’’; and in the following month he was elected a Fellow 
of the Society, but resigned in 1877. Several geological communica- 
tions from Mr. Randall have appeared in the Gronogicat Macazinn. 
We learn from the Shrewsbury Chronicle that he received a bronze 
medal for his collection of minerals and fossils at the Great Exhibition 
of 1851. He was connected with the Coalport pottery works from 
18338 to 1891, and was famous as a painter of birds on china. He has 
published several independent volumes on the history of Shropshire, 
and on Clay Industries. We offer him our sincere congratulations on 
attaining so great an age, after a long and conspicuously useful career. 

GrotoeicaAL Survey oF Inpra.— We have just received information 
that three posts of ‘ Assistant Superintendent’ (rank) in the Geological 
Survey of India are open to candidates. ‘They must have a first-class, 
all-round knowledge of geology, and a good general education; age 
not to exceed 25 years. The officers selected will be required to leave 
for India at about the end of the present year. Further particulars 
may be obtained from the Secretary, Revenue Department, India 
Office, London, 8. W. 


Ee 


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Dr. GEORGE J. HINDE, F.R.S., F.G.S. 
: Sir THOMAS H. HOLLAND, K.C.I.E, A.R.C.S., D.Sc., F.R.S., F.G.S. 
jj. Prorrsson W. W. WATTS, Sc.D., M.Sc., F.R.S., V.P.G.S. 
| Dr. ARTHUR SMITH WOODWARD, F.R.S., F.L.S., Src.Gnou.Soc., AND 
|| : HORACE B. WOODWARD, F.R.S., F.G.S. 


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| pee ee eee ce eas 
| NOVEMBER, 1910. 


@ GaN, Se eae ae = 


I. OxrteinaL ARTICLES. Bagel Notices oF Mrmorrs (continued). Page 
|| New Chalk Polyzoa. By R. Geology of Northern Nigeria. By 
| Bryponz, F.G.S. ‘Plate XXXVE} 481 Dr. J. D. Falconer, M.A. ... 519 
|| A Fossil in a Chalk Flint Pebble, Marine Bands at Maltby. a Wie Hi 
Sherringham, Norfolk. By Henry Dyson... . . 520 
Woopwarp, LL.D., F.R.S. Tele Sane 
(With five Text- figures. ) qoc . 483 Monograph of the Okapi—Atlas. By 
f The Residual Earths ef British Guiana Sir E. Ray Lankester ... ... ... 522 
i termed ‘Laterite’. By ane AMolian Deposits. By A. Iychenko 522 
| J. B. Harrison, C.M.G., Brief Notices: Caves, etc., of Belgium 
F.G.S., F.1.C., assisted by i D —Mammal Horizons, N. America 
Rew. ”( Continued.) oe . 488 —New Carnivores, W. Nebraska 
|| Pollicipes levis, a Gietioeous Game —Geologische Charakterbilder— 
pede. By T. H. Wiruers. Geology and Civil’ Engineering — 
(With five Text-figures.) ... ... 495 Liverpool Geological Society — 
The Plasticity of Rocks. By R. M. Cotteswold Naturalists’ Field Club: 
Drrtey, M.Inst.C.E., F.G.8. ... 501 ORE aaa oT ee 
; P eological Survey, Transvaal— 
ee oe onites. By G. C. 503 Wealden Retiee — Geological ©... 
‘ re k : iy 
Some Carboniferous Arachnida, By pane) Bene es 288 
R. I. Pocock, F.L.S., F.Z.8. ... 505 Iv. ConnasroxEnce. 
Hosea Manimals in Cuba. By Dr. Wi Bs Wine bier encore teal Deer OO 
J. W. Spencer, M.A. eae ra teary Woodward 720-2. f..0>.. oom 
V. Oxpituary 
II. Notices or Memorrs. : 
British Association.—Address by the Mag AEN cop SSS oe ean Eh 
President, Professor T. G. Bonney, VI. MiscELLANEOUS. 
Se.D., LL.D., F.R.S.(Conelusion.) 513 | Norwich Castle Museum... ... ... 527 
Index Generum et Specierum Ani- Royal Society, Edinburgh — ieee 


malium. By C.D. Sherborn ... 519 | Twelve Swiney Lectures on Geology 528 
LONDON: DULAU & CO., Lrp., 37 SOHO SQUARE, W. 


eS The Volume for 1909 of the GEOLOGICAL MAGAZINE is ready, 
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ROBERT F. DAMON, 
WEYMOUTH, ENGLAND, 


Begs to call the attention of Directors of Museums 
and Professors of Biology and Geology in Universities 
to his fine series of 


Coloured Casts and Models 


Rare and Interesting Fossils. 


This interesting and attractive series will form a most 
valuable addition to any Museum of Zoology or 
Comparative Anatomy, and cannot fail to prove of 
the greatest interest alike to men of Science and to all — 
Students of Natural History as well as to the general 

body of educated visitors to a public collection. 


A town about to establish a Museum would find that these 
specimens, when properly mounted and displayed in glass cases, 
with instructive labels to each, would form a substantial basis for 
a Public Museum at a very small cost. 

Directors or Curators and Professors of Colleges can obtain by 
return of post a full detailed list, and also, if desired, a list of the 
Museums in Great Britain,. Australia, Africa, America, Austria, 
Belgium, Brazil, Canada, Denmark, France, Germany, Greece, 
Holland, India, Italy, Japan, New Zealand, Norway, Portugal, 
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THE 


GEOLOGICAL MAGAZINE, 


NEV SERIES: “DECADE Vi (VOLES VITT™ 


No. XI.— NOVEMBER, 1910. 


ORIGINAL ARTICLIEHMS- 


i 


I.—Norrs oN NEW OR IMPERFECTLY KNOWN CHALK Potyzoa. 
By R. M. Brypons, F.G.S. 
(PLATE XXXVI.) 
(Continued from the September Number, p. 392.) 


STEGINOPORA DENTIcULATA, noy. Pl. XXXVI, Figs. 1-3. 


Zoarium always unilaminate, nearly always adherent. 

Zoeecia broad, length -65-"8 mm., breadth -45--55 mm., aperture 
primarily semicircular but tending to quadrangular by thickening of 
the upper lip, and with a semicircular collar, the two ends of which 
are expanded into large perforated spine bases: the arched front wall 
springs from the inside of the side walls and is pierced along its edge 
by a row of large pores, and at a short distance inside this row by 
a row of smaller pores in fairiy close correspondence with the outer 
row; the centre of the front wall is pierced by a very variable 
number of fine pores, which sometimes give clear indications of 
a third row corresponding to the two outer ones; the zocecia always 
have common side walls of considerable width; in immature stages 
(Fig. 1) the front walls rise high above the side walls, and small beak- 
shaped avicularia are scattered irregularly between them; in a further 
stage of development (Fig. 2) the side walls are greatly thickened 
and raised above the front walls, absorbing the avicularia, and the 
perforated spine bases at the corners of the aperture grow inwards 
until they meet, and are fused into a stout bar across the aperture, so 
qualifying the species for admission to the Steginoporide; in the 
stage of maximum development (Fig. 3) the bar develops a stout 
denticle in the middle of the lower edge. 

Oecia not observed. 

Rare in the zone of I. cor-anguinum at Gravesend, Broadstairs, 
Kingsgate Bay, and Leaves Green, near Bromley. 


Srecinopora GRAvENsSIs, nov. Pl. XXXVI, Figs. 4-5. 


Zoartum unilaminate, adherent. 

Zoecia long and narrow, average length ‘65 mm., breadth ‘35--4 mm.; 
with very broad common side walls, between which is deeply sunk 
the flat front wall pierced by numerous transverse paired slits, which 

DECADE V.—VOL. VII.—NO. XI. 31 


482 R. M. Brydone—Chalk Polyzoa. 


only begin to radiate quite close to the foot of the zoarium, and are so 
fine as to be rarely well visible; aperture semi-oval, with a tiny 
denticle in the middle of the lower lip and a thick raised upper lip 
often bearing three or four perforated tubercles; the corners of the 
aperture are overhung by two stout perforated spine bases projecting 
from the upper hp, which often fill up and unite to form an arch 
across the lower part of the aperture; small perforated tubercles 
are scattered irregularly and sparingly on the side walls; these features 
are often very feebly marked. 

Oacia not observed. 

Avicularia may be represented by the perforated tubercles. 

Very rare in the zone of IZ. cor-anguinum at Gravesend. 

It will be observed that the two foregoing species represent a very 
early stage in the evolution of the Steginoporide ; it is curious that 
no species of this family is yet known to occur at any later horizon 
in the English Chalk. : 


MeEMBRANIPORELLA FALLAX, nov. Pl. XXXVI, Figs. 6-8. 


Zoarium unilaminate, adherent. 

Zoecia oval, average length -7--8 mm., breadth *35—-4mm.; the 
arched front wall rests on the side walls, and is pierced by seven or 
eight paired diverging slits extending from the edge’ about half-way 
toward the middle line: aperture semicircular, showing in ordinary 
specimens (Fig. 6) two imperforate tubercles on either side when 
there is no ocecium, the upper pair of which are picked up by and 
form the starting-point of the ocecium when one is formed, as is 
usually the case; the lower lip of the aperture often bears a median 
denticle of very variable size. Such specimens give a delusive 
appearance of organization similar to that of Cribrilina furcifera, but 
in the upper right-hand corner of Fig. 7 there may be observed 
a zocecium which shows that what appear to be a pair (the lower pair) 
of tubercles and a median denticle are in fact the scanty remains of 
the true lower lip of the aperture, which has almost invariably been 
broken away: in another zocecium in the same figure it is preserved 
on one side only. i 

Owcia long and narrow, very generally present; they often appear 
to throw out a sort of causeway leading on to the front wall of the 
zocecium (if any) immediately succeeding the same line. 

Avicularia beak-shaped, small, but very deep, with a slender bar, 
which is rarely preserved, across the aperture; generally lying more 
or less on their sides and with a strong tendency to occur singly or in 
pairs with their beaks directed downwards or inwards at the head 
of the zocecium. Fig. 8 shows a specimen of exceptional regularity 
in this respect. 

The species is not uncommon in the zone of Jf. cor-anguinum at 
Gravesend, and a dwarfed form has been found at the top of the 
zone of Marsupites at two places in Hants. It comes nearest to the 
form figured by Novak! as Lepralia pediculus, Rss., but is easily 


' Novak, Denkschr. d. k.k. Ak. d. Wiss. zu Wien, Math.-Naturw. Cl., 
Bd. xxxvii, p. 98, pl. i, fig. 12. 


Ay 


GeEo'. Maa. 1910. 


PLATE XXXVI. 


R. M1. Brydone, Photo. 


Bemzrose, Collo. 


CHALK POLYZOA. 


Dr. H. Woodward—A. Fossil in a Chalk Flint. 483 


distinguished from it and still more easily distinguished from Reuss’ 
original figure.! 


MeEMBRANIPORELLA PUSTULOSA, Nov. Pl. XXXVI, Fig. 9 


Zoarvum unilaminate, adherent. 

Zoecia long and slender, average length ‘7-8 mm. mes ‘3-4 mm. 
the aperture is enclosed by a raised ring which is either truly cir aa 
or slightly broader than long, and merges in the upper part with the 
oceclum, much as in MZ. castrum; the side walls are thin, exsert, and 
quite separate from those of the adjoining zocecia; the front walls are 
formed by a broad backbone united to the side walls by about seven 
ribs springing from the inside of the side walls and with well-marked 
and sometimes considerable spaces between them. 

Oecia globose, without external aperture, and cutting into the front 
wall of the succeeding zocecium ; they are almost invariably present. 

Avicularia mandibular, thin-walled, small but wide; in normal 
zocecia there is always one on either side of the aperture with the 
beak pointing downwards, and others occur irregularly along the 
side walls. 

Occurs in all zones from that of JL. cor-anguinum to that of 
B. mucronata. 

This species is closely related to Cellepora galeata, Hag.,* in which 
species, however, the apertural ring is distinctly longer than broad, 
the spaces between the ribs are very short and do not reach the side 
walls, there is only a very slight swelling to suggest an ocecium, and 
the side walls are broad and common. 


EXPLANATION OF PLATE XXXVI. 
(All figures x 12 diams.) 


Steginopora denticulata. Gravesend. 

Ditto. Broadstairs. 

Ditto. Gravesend (another specimen). 
Steginopora Gravensis. Gravesend. 

Ditto. Gravesend (another specimen). 
Membraniporella fallax. Gravesend. 

Ditto. Gravesend (another specimen). 

Ditto. West Tisted, Hants. A dwarfed form. 
Membraniporella pustulosa. Gravesend. 


CONIA Ar WOW 


’ T].—A Fragment or a Fosstt 1x a Cuatx Frint PEBBLE FROM THE 
SuerrineHamM Bracu, Norrork. 


By Hunry Woopwarp, LL.D., F.R.S. 


fW\HE difficulties which the paleontologist encounters in attempting 

the interpretation of fossil organic remains are numerous, 
especially when compared with the task of the zoologist in the 
study of recent forms. Im a fossil, for instance, the soft parts of the 
animal are wanting, while the anil or exoskeleton is often remarkably 


1 Das Elbthalgebirge in Sachsen, pt. ii, p. 129, pl. xxiv, fig. 16. 
2 In Geinitz, Grundriss d. Versteinerungshunde, p- 613, pl. xxild, fig. 34. 


484 Dr. H. Woodward—A Fossil in a Chalk Flint. 


dissimilar from that of its nearest living allies. Furthermore, the 
object he has to deal with has undergone mineralization, more or less 
completely, so that its appearance is greatly altered. But most 
frequently the object placed before him is only a fragment of the hard 
part of some animal which he is nevertheless called upon to identify 
at once. 

Here is a case in point: my friend Mr. W. H. Paterson requested 
me to name a fragmentary fossil embedded in a waterworn flint from 
the Chalk, picked up by Mrs. Paterson some years since on the beach 
at Sherringham, Norfolk. The structure (whatever it might be) 
occupied only a part of the pebble (Fig. 1), and was also partially 
exposed on the reverse side (Fig. 2). It was certainly not related to 
the ordinary forms of inorganic markings known as ‘ banded flints’, 
which frequently occur as flint pebbles on our shores, and were at 
one time believed by Dr. Bowerbank and others to be the remains of 
fossil sponges. My brother, the late Dr. 8. P. Woodward, described 
a number of these in a paper in the Grotogica, Macazine (1864, 
Vol. I, pp. 145-9, Plates VII and VIII). ‘The banded structure in 


IZ = = 
ZEA 
ZZ = 
i -: 
———— 


Inte, Il. Fic. 2. 


Fie. 1, obverse; Fie. 2, reverse side of waterworn flint pebble from the beach at 
Sherringham, Norfolk. In the collection of W. H. Paterson, Esq. 


these flints is certainly due in many cases to deposition (op. cit., 
Pl. VI, Fig. 4), but in other instances the banding, if not caused 
by, 1s accentuated by the introduction within the flints of mineral 
colouring matter, carried in solution by water permeating the flint 
along lines of least resistance; for even flint contains much water 
interstitially within its pores, which escapes by evaporation when 
flints lie exposed upon the surface. Instead of the transverse lines 
seen in ordinary banded flints, the surface of the Sherringham pebble 
displays about fifteen imbricated, scale-like markings upon its front or 
obverse (Fig. 1) side, and two or three additional ones (evidently part 


Dr. H. Woodward—A. Fossil in a Chalk Flint. 485 


of the same structure exposed on the reverse side) near the top end of 
the flint (Fig. 2). I assume, for description, that the convex edge 
of the scale-like markings is the upper margin as shown in the 
drawing. 


Measurement of scales from exposed base to summit. 
From base, scale No. 1is 8mm. broad by 5 mm. high. 
9 |< 


= 15 te) re) 2) ye) 
3 12 9 ”? 5 yh) 
ee esse » GP os 
5 13 Ue) 27 13 7 
6 16 Uk) ” 7 ” 
7 23 9 De) 9 bib) 
8 17 29 29 8 tT) 
9 15 7 ie) 5) ”? 
10 15 Ie WL Osey me 
La Ca Nyt GoM 
12 We 29 ? 4 2 
13 20 9 We) 5 oe) 
fic wae al 


bi) 


To summit ey NS ae si 4 ed 

Scales on reverse side exposed near the summit of the flint. 

Nos. 12 and 14 both wrap around the edge of the flint, and appear on the reverse 
side also, intercalated with Nos. 16 and 17. 

No. 16 is 20 mm. broad by 10 mm. high. 
iN 10 9 99 5 9? 

The upper portion is obscured, being, like the rest of the pebble, 
much worn down by rolling and attrition. The lower part of the 
pebble is composed of a dark amorphous flint which merges into 
a lighter shade near the scale-like markings. 

If we compare the specimen before us with the rare remains of 
Coniferous cones met with in a fossil state, I cannot remember to 
have seen a silicified Cretaceous example, nor one in which the 
carbonaceous matter was not preserved and showed the separate 
bracts visibly overlapping one another from the apex to the base. 
This is not the case in the fossil in flint we are considering. 


I suggested to Dr. Arthur Smith Woodward that possibly the specimen 
might represent a fragment of a fossil fish, but he pointed out to me 
that the scale-like markings are not uniform, nor are they arranged 
symmetrically, also that they have been worn away to one level, and 
have no structure visible. 

I compared the pebble with a fish-coprolite from the Chalk, but 
although these bodies have an arrangement in layers the phosphatic 
material composing them is always preserved, and they have never 
in my experience been met with silicified or enclosed in a chalk flint. 

I submitted the rolled flint to Dr. F. A. Bather, but after a careful 
examination he wrote on the label the following note: ‘‘No one 
in the Geological Department considers the markings organic. The 
bands have no appreciable thickness. (F. A. B.)” 

I wrote to my friend Dr. Hinde to ask whether the specimen might 
possibly be attributable to a fossil sponge, chalk sponges being most 
abundantly met with in that formation enclosed in flints. He replied 
that the markings did not resemble those of any sponge with which 
he was acquainted. 


486 Dr. H. Woodward—A Fossil in a Chalk Flint. 


I then placed the specimen before me and meditated upon it from 
time to time, a process which I have frequently found tended to 
illumination. I recalled the well-known fact that there are quite 
a number of corals and mollusca which build up body-chambers 
needlessly large for their personal accommodation, and then proceed 
to reduce them again by shutting off a portion from time to time 
by secreting a shelly partition or septum across the lower part of 
the living-chamber.' Such energy in shell-growth has been attributed 
to various causes:—(1) There may be a necessity for the animal 
to grow upwards to prevent its being immersed in sand or other 
sediment which threatened to overwhelm the sedentary mollusc or 
coral. (2) Professor H. G. Seeley suggested that more rapid shell- 
growth in Cephalopod shells was due to a periodic necessity to 
provide a larger body-chamber to accommodate the gravid oyisacs 
of the female prior to the extrusion of the ova. (3) Professor Owen 
suggested that the mantle of the mollusc, which secretes the shell, 
deposited new matter to its outer border more rapidly than it does 
to the umbonal or hinge-area. 


eS 


<< 


= 


Fic. 3. Section of a portion of the shell of a long-beaked oyster, Ostrea cornucopia, 
showing interior (umbonal) portion of valve filled up by a series of 
extremely thin lamellee (c), quite distinct from the compact shell-wall 
(s, s) ; @, part of the body-chamber occupied by the animal. (From 
Dr. 8. P. Woodward’s Manual of the Mollusca, 1851-6, Isted., p. 281, 
fig. 192.) 

This addition to the margin of the shell compels the animal to 
advance its body and the attachment of its shell-muscles also, in order 
to follow this forward or upward growth of the shell. To obviate 
the excess of space thus acquired the lining-mantle of the animal 
partitions off the lower portion of its body-chamber by secreting 
a series of shelly layers, very regular in Cephalopod shells, such as 
the Nautilus and Ammonite, but more or less irregular in the other 
Mollusca, such as the Water Spondylus, the Exogyra, and some 
Hippurites and Oysters. (Fig. 3.) 

1 See a series of illustrated articles ‘‘ On the Form, Growth, and Construction of 
Shells’? by the late Dr. S. P. Woodward, edited by H. Woodward, in the 
Intellectual Observer, vol.x, pp. 241-53, November, 1866 ; vol. xi, pp. 18-30, 161-72, 
1867. See also Henry Woodward, ‘‘ The Pearly Nautilus, Cuttle-fish, and their 
Allies’: Student and Inteliectual Observer, vol. iv, pp. 1-14; pt. ii, pp. 241--9, 1870. 
‘* On the Structure of the Shell of the Pearly Nautilus,’’ 1870, Brit. Assoc. Sect., 


Liverpool Meeting, p. 128. ‘*On the Structure of Camerated Shells’’?: Popular 
Science Review, vol. xi, pp. 113-20, pl. lxxxii, 1872. 


Dr. H. Woodward—A Fossil in a Chalk Flint. 487 


In some corals the lower portion of the corallite chamber may be 
shut off by nearly regular simple horizontal septa, as in Favosites, 
or the interior may be filled by irregularly formed meniscus-like 
cells filling up the central cavity below each polype, as seen in the 
Zoantharia Rugosa. In Ostrea cornucopia (Fig. 3), and in a species 
of oyster from the Tertiary of Cerigo, Jonian Isles, in Mr. W. J. 
Hamilton’s Collection (Brit. Mus. 34033), a large portion of the interior 
of the shell is shut off by numerous irregular septa forming, as in 
Spondylus, water-cavities within the shell. These inner septal shell- 
layers are quite distinct from the outer shell-wall, they are much less 
compact, the lamelle are extremely thin, and they are often dissolved 
out entirely in the fossil forms. 

In those singular molluscs the Rudistes we have forms like 
Hippurites organisans, Montf., in which a portion of the lower 
deep valve is partitioned off, like an Orthoceras, by a succession 
of almost regular septa, the intervening spaces forming water- 
chambers (Zittel, Paleont., p. 282, fig. 632, 1895). 


Gan oe 


Fic. 4. Part of the internal mouw/d taken from the interior of a shell of Radiolites 
Mortoni, Mantell (reduced), representing some of the water-chambers 
of the original shell, perforated by cliona. +, 7, joints produced by the 
decomposition of the septa; a, furrows produced by adductor ridges ; 
t, furrows produced by the dental ridges. From 8. P. Woodward’s 
article in Q.J.G.S., vol. xi, pl. v, fig. 2, 1855. 

Fic. 5. Diagrammatic vertical section through shell of Radiolites, showing s, s, the 
outer shell-wall composed of prismatic cellular structure, the prisms being 
vertical to the shell-laminze and minutely subdivided. ¢, section of the 
inner layer composed of transverse lamelle, which are extremely thin, 
and are separated by intervals, like the water-chambers of Spondylus, and 
the similar spaces in the umbonal cavity of the long-beaked oysters. 
(See Fig. 3 supra; compare also with Fig. 1.) 


In the British Cretaceous species Spherulites (Radiolites) Mortons 
the outer shell-wall is very thick and consists of dense prismatic 
cellular structure, like the recent Pinna. The lower central part 
of the valve has been shut off from time to time by a series of 
somewhat irregular meniscus-like septa, deposited by the mantle and 
built wp in succession one upon another. In a specimen described by 


488 Professor J. B. Harrison—‘ Laterite’ in British Guiana. 


Dr. 8. P. Woodward in his classical paper ‘‘On the Structure and 
Affinities of the Hippuritide” (Quart. Journ. Geol. Soc., vol. xi, 
pp. 40-61, pl. v, figs. 1, 2, 1855), and preserved in the British 
Museum (Nat. Hist., No. 38219), obtained from the Iieraster 
cor -anguinum zone of the Chalk at Rosherville, Gravesend, the internal 
chambers have been filled up solid and the extremely thin, shelly 
septa afterwards dissolved away, leaving only an internal mould 
composed of very hard chalk representing some of the chambers of the 
original shell (see Fig. 4). The shelly septa, always very thin and 
fragile, are commonly entirely dissolved out, or, as in this instance, 
replaced by a mould of chalk or flint, the shells of many Radiolites 
being more or less converted into or embedded in flint, as is also the 
case with the shells of Znoceramus from the Chalk. 

Here, then, I think we have succeeded in finding a solution for the 
exceedingly puzzling rolled fossil in flint from the Sherringham Beach, 
and I feel justified in considering it to be the waterworn fragment of 
the chambered portion of the shell of a Radiolite, and most probably 
of FR. Mortoni, replaced by silica. ‘he outer prismatic cellular shell- 
wall in which this chambered portion was originally enclosed (see 
Fig. 5) has entirely disappeared, and the only evidence left is a relic 
of the mould in flint, of the chambers of which we see only the thin 
edges as they pass inwards to form in succession the series of transverse 
floors of what had been at one time a part of the body-chamber of the 
animal. 


III.—Tue Resmpvat Earras or British GursNA COMMONLY TERMED 
‘ LATERITE’. 


By Professor J. B. Harrison, C.M.G., M.A., F.G.S., F.1.C., assisted by 
K. D. Rerp, Assistant Analyst British Guiana. 


(Continued from the October Number, p. 452.) 


({\HE Christianburg and Akyma deposits afford excellent examples 

of the highly aluminous or bauxitic type of laterite formation. 
They here occur as parts of a residuary deposit derived from the 
decomposition in situ of an igneous rock, probably a porphyrite or 
a tuff, an almost pure quartz-sand, and masses of bauxite containing 
in the more aluminous varieties from 92°6 to 94:4 per cent. of the 
hydrates of alumina and in the ferruginous ones 64°6 per cent. of 
the hydrates of alumina with about 24 per cent. of the oxides and 
hydrates of iron. 

The Christianburg and Akyma deposits illustrate excellently the 
extreme of the formation of laterite, where the igneous rock, in place 
of weathering to a mixture of quartz, of kaolinite, of bauxite, and of 
the oxides and hydrates of iron, changes almost completely to quartz 
and to hydrates of alumina and the oxides and hydrates of iron. No 
explanation of the extreme intensity of the lateritic action in the 
Christianburg—Akyma district is at present obtainable. But as it is 
proposed to work the deposits I may be able to obtain further 
information when clean sections of them are available. 


Professor J. B. Harrison—‘ Laterite’ in British Guiana. 489 


The foregoing examples represent the types of the residual deposits 
in situ in British Guiana, which I have regarded as and termed 
laterite. The concretionary masses in various parts of them range 
from ironstones with in round figures 93 per cent. of iron-ores and 
with less than 2 per cent. of aluminium hydrate to bauxites with less 
than 2 per cent. of iron-ores and with over 94 per cent. of aluminium 
hydrate. But the main bulk of the residual deposits in situ correspond 
to those which G. C. Du Bois in his monograph termed “ Eluviale 
Laterite (primaire Laterite)’’, or ‘‘ Kieselsdurereiche Laterite ” 

They are essentially buff, ochreous, red-brown or chocolate-coloured, 
ferruginous, more or less siliceous, clays and earths; and consist of 
mixtures in various proportion of angular quartz-sand and siliceous 
grit derived in part from quartz originally present in the rock of 
which they are products and in part secondarily from the decom- 
position of the felspars; of kaolinite, of bauxite, and of limonite, 
or other more or less hydrated oxides of iron, derived from the 
decomposition, hydration, and oxidation of the constituents of the 
felspars and of the ferro-magnesian minerals. 

The mean proximate composition of the British Guiana lateritic 
earths which I have examined is in round figures :— 


TABLE X. 
Quartz . 5 3 : 3 5 94 
Tron-ores (including pisolites) : ; 32 
Kaolin, Sericite, and other felspathie debris, ete. : 24 
Bauxite . : c : : 2 ¢ : 20 


100 

The earths I quoted as examples of the lateritic earths in my work 
on the Geology of the Gold-fields of British Guiana by weathering, 
detrition, washing, and re-arrangement of their proximate constituents 
could give rise to deposits consisting mainly of quartz-sand and ot 
more or less bauxitic masses. For instance, the Tumatumari earths, 
if separated by natural elutriation, would give rise to a quartz-sand, 
say with 90 per cent. of quartz, and to bauxite with 63 per cent. of 
aluminium hydrate and 20 per cent. of iron-ores. 

Whilst in the examples discussed there is no difficulty in tracing 
the silica set free during the decomposition of the rock into the form 
of masses of quartz as at Issorora, or into that of quartz-sand as in 
the earths from Tumatumari, Omai, Mazaruni, and Christianburg— 
Akyma, there are other cases in which little of the silica remains 
through the mass of the laterite. In some of these the ferruginous 
or aluminous lateritic earths are traversed by numerous thin veins of 
secondary quartz which intersect one another in all directions. These 
quartz-veins, which towards the surface of the laterite are not 
infrequently auriferous to paying extents or to even well-marked 
degrees, lessen in their contents of gold and tend to become barren 
when followed to a depth where they gradually thin completely out 
before reaching the less altered layers which are just above the 
undecomposed rock. In other places, as I have described elsewhere, 
the silica has segregated out in the form of lenticular masses not 
uncommonly described as ‘ quartz-reefs ’. 


490 Professor J. B. Harrison—‘ Laterite’ in British Guiana. 


Among places where the origin of the auriferous veins and masses 
of secondary quartz which occur in the laterite of the Guianas has been 
discussed, I may mention p. 41 of Guide Pratique pour la recherche et 
Vexploitation de Vor en Guyane Frangaise by M. EK. D. Levat (1898), 
pp- 21 and 22 of G. C. Du Bois’ above quoted work on the Surmam 
laterite (1903), pp. 11 and 12 of the Geology of the North-Western 
District of British Guiana by H. I. Perkins and myself (1897), 
pp. 208 and 209 of the Geology of the Gold-fields of British Guiana 
(1908), and pp. 28 and 29 of Goudindustrie in Suriname by 
E. Middelberg (1908). 

The attention of the technical geologists and the mining experts who 
have personally studied on the spot the residuary lateritic formations 
of the Guianas has necessarily been more attracted to the occurrence 
and nature of the secondary veins of auriferous quartz and to the gold 
disseminated in them than to the, from their poimt of view, very 
subordinate question of the presence or not of free aluminium 
hydroxide in the earths. 

Decomposed Granites, Kaolins, or Pipe-clays.—The following are 
analyses of a granite and of a hornblende granitite, and of the 
products of their decomposition by weathering in situ, and of similar 
products of a granite, and of an aplite of which the compositions are 
not known :— 


TABLE XI. 


San San 


Mazaruni. Mahdia. Kopai. 


Orealla. 


Upper | Couran- 
Mazaruni River. | Potaro River. | |Mazarunij _lyne 
River. | River. 


| Pipe-clay| Pipe-clay 
Granite. |Pipe-clay Homnblenee Pipe-clay es i dota ‘ 
5; Granitite.| Aplite. 
Quartzeee ey a he ee 36°60 38°70 29°50 88°15 
@ollordiSulicae “Spe 1:60 “43 
Combined Silica. . Blea 27°68 38°70 25°24 
Aluminium Oxide . 13°98 19°82 15:83 | 24°60 
Tron Peroxide 0:93 2°05 2°86 2°67 
Tron Protoxide . . 0°46 0°51 
Magnesium Oxide . 0:72 itil 2°14 “39 
Calcium Oxide . 0°88 nil 3°49 “10 
Sodium Oxide 2:80 39 3°07 nil 
Potassium Oxide 4°81 50 2°88 “41 
Water 2 0°74 8°52 0°50 6°92 
Titanium Oxide. . . 0°62 | *85 0°46 1°01 
Phosphoric Anhydride . 0°06 “01 0:01 nil 
Manganese Oxide 0:24 | trace 0°08 nil 
100 | 100°28 100:03 | 99:93 


Their mineralogical compositions are shown as follows :— 


Professor J. B. Harrison—‘ Laterite’ in British Guiana. 491 


TaBLE XII. 


| Mazaruni. Mahdia. Ropai | Ozealla. 
Upper | Couran- 
Mazaruni River. Potaro River. Mazaruni| lyne 
River. | River. 
: Pipe-clay| Pipe-clay 
Granite. |Pipe-clay Brom eae Pipe-clav| from u from 
; anite. A) eee : 
ranite. | Aplite. 
(Qyierti; aig | Gaede ae 36°6 38°7 29°5 38°1 48°3 6°7 
Colloid Silica 1°6 “4 14 3°8 
Orthoclase pecan MS 20°6 2-9 15°5 2-4 1:9 iL 
ae TOCaSe Ma yl a. Zo 374 37° 5 34 4:6 ~ 
INI CARMAN yet) os eats 13°3 3°3 
Hlornblende . . . . . 1207 
Nineties 5. Be ae Tea 
Iimoniteew we. °8 1°8 8 1°6 
Mitmentes =... 3 1°6 1:9 1:9 “02 
pSphenewes . sia) 4 SP 162 1-2 ; 
Meaolimitery Ys. 6 4s 50°2 48°6 42 80:4 
Tale Ab ears 3 Loy sil 2 
fmiauKigemeees Lh nil 4-9 nil 2 
Minor constituents. . . 7) 3 of) 
100°2 100 100 100 100°4 100°32 
ED IASMOLC Mee ses 14 
Gib bsiteyn fakes 3°5 2, 
{Total Alumina present in nil 4°6 nil oil 
Bauxite 


These products of granites decomposed in situ may be termed either 
decomposed granites, kaolins, or pipe-clays. They are white or 
creamy-white, soft, earthy rocks which do not harden on exposure to 
the atmosphere, but gradually crumble down when wetted by rain. 
They are mixtures of varying proportions of sharply angular quartz- 
sand and of clay-substance (kaolinite with a little finely divided 
felspathic rock powder, or flour), with usually small proportions of 
colloid silica, either without or with aluminium hydrate in more or less 
negligible proportions, with a little ilmenite. and with very small 
proportions of limonite. 

Another type of the residual products of the alteration, probably 
largely by deep-seated hydro-metamorphism of pegmatites and aplitic 
granites, is the sericitic one. This type is at times erroneously 
regarded as produced by ordinary processes of weathering. The 
rocks are glistening white, exceedingly soft, silky-feeling masses, 
which do not harden on exposure to the air, but quickly disintegrate 
to a sandy powder when moistened by rain or when placed in water. 
Their chemical compositions, their physical properties, and the 


492 Professor J. B. Harrison—‘ Laterite’ in British Guiana. 


microscopical examinations of them show that sericite is present in 
them to a considerable extent. The chemical compositions of two 
typical specimens are as follows :— 


TasLe XIII. 


Minnehaha, Mindrinetti, 
Potaro District. Surinam. 

Quartz ; é : ‘ , Boo 20°30 
Colloid Silica : : : ; “40 38 
Combined Silica . ; : : 32 26°28 
Aluminium Oxide . : ; : 31°49 34°10 
Tron Peroxide ; : 5 : “68 6°56 
Magnesium Oxide . ; . , “21 Oi 
Calcium Oxide . , ‘ : 10 “02 
Sodium Oxide ; ; , : oD) 39 
Potassium Oxide . : ; , Woe Oe 
Water : : : A - 9°67 8:43 
Titanium Oxide . : ; . 67 1 
Phosphoric Anhydride . ( : nil nil 
Manganese Oxide . : 6 ; nil nil 

99°95 99°70 


Their proximate mineralogical compositions appear to be— 
Taste XIV. 


Minnehaha, Mindrinetti, 
Potaro District. Surinam. 
Quartz : 4 ; ; : Deiow7 20°3 
Colloid Silica , j +4. 4 
Sericite 14°3 21:6 
Kaolinite 53:9 34:0 
Tale Or 9 
*7 Bauxite 6:0 15:0 
Ilmenite ios} 2-0 
Hematite 5:5 
Minor constituents » °3 
100 100 

*Diaspore 371 12°8 
Gibbsite : ‘ : : 2°9 DoH) 
{Total Alumina present in Bauxite . 4°6 12:3 


These earths are mixtures of fine, sharply angular quartz-sand, 
kaolinite, and sericite, with lesser proportions of bauxite, the latter 
being present to the extent of 6 per cent. in the Minnehaha sample 
and to 15 per cent. in the one from Surinam. The principal 
differences between the Muindrinetti sample and the Omai sericitic 
laterites already described are in the higher proportion of limonite 
present in the latter and in the higher state of hydration of its 
bauxite. The more highly hydrated rock shows the setting power 
of true laterite; the rock of lower hydration does not in any way 
exhibit it. 

Both these sericitic earths are more or less auriferous, and have 
been worked for gold. 

Neither the pipe-clays, the products of the decomposition of 
granites, pegmatites, more or less aplitic granitite, and aplite in situ, 
nor the sericitic earths, their alteration products, have any claim to be 


Professor J. B. Harrison—‘ Laterite’ in British Guiana. 493 


termed laterite, as they neither indurate on exposure to the atmosphere 
nor do they consist mainly or even to any extent of the hydrates of 
alumina. 

Rocks other than highly aluminous ones showing to marked degrees the 
characteristic property of Buchanan's Laterite.—The gradual setting 
or hardening on exposure to the atmosphere of residual masses is 
not a characteristic only of ‘either purely ferruginous, partly 
ferruginous and partly aluminous, or purely aluminous deposits. 
It may characterize to even a more marked degree other residuary 
deposits from igneous rocks. As an instance I may mention a mottled, 
ereamy-white, and dark-red deposit which occurs in a low cliff at 
Kongkamo near the Ireng River in the territory recently assigned 
to Brazil. This is a clay-like mass which when first dug is quite 
soft and can be cut lke cheese by an iron knife.! Upon exposure 
to the air the mass indurates gradually until the creamy-white parts 
attain a hardness of from 3:5 to nearly 4 of Mohs’ scale, the dark- 
red parts becoming still harder. The composition of this material is 
shown by the following analysis :— 


TABLE XY. 

Quartz . : F P : “94 
Colloid Silica . F p : 5 -58 
Combined Silica. : ; J 43°82 
Aluminium Oxide . : ; i 30°49 
Tron Peroxide j : , : 4-40 
Magnesium Oxide . : ‘ : “41 
Calcium Oxide j : : : oy) 
Sodium Oxide ; 5 4 ; 63 
Potassium Oxide . : ; ; 7°53 
Water . : 3 d , ; 5:23 
Titanium Oxide . : : : 60 
Phosphoric Anhydride. : 3 trace 
Manganese Oxide . : : 6 nil 


This corresponds to the following mineralogical composition :— 
Taste XVI. 


Quartz . 1 
Colloid Silica 6 
Orthoclase 44-4. 
Plagioclase 59 
Kaolinite Dial 
Tale 1°3 
*+ Bauxite 19°5 
Ilmenite i199) 
Hematite : 3°8 
Minor constituents . a) 


100 
*Diaspore : - : : ‘ 14:2 
Gibbsite 5 : 5:3 
Total Alumina present in Bauxite 17-4 


Microscopic examinations show that it is a like the ferruginous © 
and aluminous masses of the lateritic earths, an alate or 


1 Tt is thus used by the aboriginal Indians in making images and other carved 
ornaments. 


494 Professor J. B. Harrison—‘ Laterite’ in British Guiana. 


a concretionary mass, but that it is made up of exceedingly fine 
felspathic rock powder, a few particles of which show the 
characteristics of plagioclase, with varying proportions of kaolinite, 
bauxite, and oxide of iron. Although it cannot be described as 
‘laterite’ when judged on the lines laid down by Mr. Crook, its 
properties closely resemble the characteristic ones ascribed to that 
substance by Buchanan, and on account of which he proposed for it 
the name ‘laterite’. 

Oolitic ‘ Laterite’.—Du Bois, in his monograph on the laterites 
of Surinam, showed as figs. 2, 3, and 6 of pl. i two varieties of 
the components of Surinam laterite which he termed respectively 
‘« pisolithischen Kisenerzkonkretionem”’ and ‘‘ oolithartigen Beauxit”’. 
I have obtained specimens closely resembling in general appearance 
these types—a red ferruginous one from near Arawak Matope on the 
Cuyuni River and a white one from the Berbice River. The specimen 
from the Cuyuni River consists of spheroids filled with dark-red ochre 
surrounded and cemented together by a white cementing material 
having a concretionary structure. It is an aggregate of ironstone 
pisolites cemented into a mass. That from the Berbice River consists 
of white and yellowish-white and of a few reddish spheroids cemented 
together by a white material in a similar manner to the Cuyuni 
specimen. When first obtained the specimens were quite soft, and 
could be very easily cut with a knife, the spheroids being the harder 
parts of them. The cementing material has gradually hardened, and 
now the rocks are somewhat harder than are any of the specimens of 
purely ferruginous or aluminous concretionary laterite I have described 
in this paper. The cementing material is now the hardest part of the 
specimens, the innermost part of the spheroids the softest. From 
their very marked properties of induration on exposure to the atmo- 
sphere these rocks appear to have a well-founded claim to the term 
‘laterite’ as used by Buchanan. But they are not laterite in the 
sense of being mainly aluminous in composition, the restriction which 
has recently been superimposed on Buchanan’s original description 
of laterite. This is clearly shown by the chemical and proximate 
mineralogical compositions detailed in the following analyses :— 


Taste XVII. 
Matope, Cuyuni Berbice 


(red). (white). 
Quartz s : : : : “06 6°79 
Colloid Silica : : : : *40 33 
Combined Silica . : : ; 24°07 36°92 
Aluminium Oxide . P ; : 21-42 34°82 
Tron Peroxide 5 : : ; 40-80 3°85 
Magnesium Oxide . ; : : “85 16 
Calcium Oxide : : : ; SIL 7/ ‘07 
Sodium Oxide E : : : nil nil 
Potassium Oxide . ; : m 20 32 
Water . 5 d : F : Tbe 12°74 
Titanium Oxide . ' } : *95- 3°85 
Phosphoric Anhydride . : : trace trace 
Manganese Oxide . c ‘ : nil nil 


100°33 99°85 


T. H. Withers—Pollicipes levis, Shy. 495 


Taste XVII (continued). 


Matope, Cuyuni Berbice 

(red). (white). 
Quartz é =a 6:8 
Colloid Silica “4 “3 
Orthoclase 1:2 1:9 
Plagioclase . 8 3 
Kaolinite 45°5 76°3 
Tale DOF “4. 
*+Bauxite 4+4 6°5 
Ilmenite 1:9 7:4 

Hematite 19 
Limonite ; 2 ; P 24-2 traces 
Minor constituents : : : oil 
100°2 100 

*Gibbsite F 4 : F : 4-4, 6°5 
ft Total Alumina present in Bauxite . 2-9 4:2 


The cementing material of these rocks is kaolinite with varying 
proportions of felspathic rock powder and perhaps some bauxite. 
The contents of the spheroids in the red’ one from the Cuyuni is 
presumably a mixture of oxide and hydrate of iron, of which con- 
stituents the rock contains over 40 per cent. In the white one 
from the Berbice River both spheroids and cementing material appear 
to consist mainly of kaolinite with some bauxite. In their com- 
positions the rocks offer little resemblance to those of the two 
varieties of purely ferruginous and purely aluminous laterite described 
by Du Bois which they so very closely resemble in other respects. 


(Lo.be concluded in the December Number.) 


TV.—Tue Cretaceous CrreiPeDE PoLLicrPes L&VIS, J. DE C. Sowersy. 
By Tuomas H. Wiruers. 


DE C. SOWERBY (1886, p. 335) founded two new species of 

» Pollicipes from the Gault of Folkestone. To the one, based 
on a carina and tergum, he gave the name P. levis (p. 335, pl. x1, 
fig. 5); to the other, based on a rostrum and one of the latera of the 
lower whorl, the name P. wngwis (p. 335, pl. x1, fig. 5*). He also 
referred a carina and tergum from the Upper Greensand of Blackdown 
to P. levis (p. 340, pl. xvi, fig. 1), but published no description 
of them. 

J. Steenstrup (1837, p. 363) founded the species P. elongatus on 
a scutum and tergum from the Danian of Denmark, but later (1839, 
p- 409, pl. v, figs. 7-11, 7*) referred the type-specimens, with other 
valves, to Sowerby’s P. levis. 

Subsequently, C. Darwin (1851, p. 55) maintained the species 
P. elongatus, at least for the scutum, and (p. 65) recognizing 
that the valves from the Gault of Folkestone described by Sowerby 
under the names P. levis and P. unguis represented a single species, 
thought it advisable to adopt for it Sowerby’s name of P. unguis, 
especially as Steenstrup (1839) had described valves belonging to 
different species under Sowerby’s name P. levis. 

The valves from the Upper Greensand of Blackdown remain to be 
considered. 


496 T. H. Withers—Pollicipes levis, Shy. 


Since it cannot be ascertained that the specimens figured by Sowerby 
are still preserved, it is proposed to describe and fioure some similar 
valves from the same horizon and locality, formerly in the collection 
of the late W. Vicary, F.G.S. They were recorded by the Rev. W. 
Downes, F.G.S8., in List of Fossils from Blackdown (Q.J.G.S., 1882 
vol. xxxviii, p. 86), and are now preserved in the British Museum 
(Natural History). 

C. Darwin (1851, p. 80) says of the valves figured by Sowerby 
‘«... the P. Jevis from Blackdown . .. seems to be certainly 
a distinct species, and possibly a Scalpellum: no details are given” 
Darwin apparently did not see the actual specimens, or he would at once 
have recognized that they did not belong to Scalpellum but to Pollicipes. 
The parietes of the carina are not separated by any defined ridge or 
angle from the tectum as in Scalpellum, neither is the tergo-lateral 
margin of the scutum divided into two distinct lines, as is the case in 
Scalpellum, owing to the abrupt ending of the upturned lines of growth. 

Since there is a general similarity in the characters of these valves, 
and since no other Cirripede remains have as yet been found associated 
with them in the Blackdown Beds, it seems safe to regard them as 
belonging to a single species, namely— 

PoLLICIPES IMBRICATUS, sp. nov. Figs. 1-3. 
1836. Pollicipes levis, J. de C. Sowerby, Trans. Geol. Soc., ser. 11, vol. iv, p. 340, 
pl. xvi, fig. 1 (non pl. xi, fig. 5). 

Diagnosis. — Valves thin, composed of a number of consecutive 
and slightly imbricate segments, the lines of junction being marked 
on their external and inner surfaces by shallow obtusely V-shaped 
grooves. Scutum trapezoidal in outline; apex blunt; occludent 
portion twice as wide as the tergo-lateral portion; basal margin 
nearly at right angles to the occludent margin, and to the lower 
part of the tergo-lateral margin; there is no deep pit on the inner 
surface for the adductor scutorum muscle. Carina triangular in 
transverse section, with basal margin angular (about 92°). 

Material.—A nearly perfect carina on a hard shelly matrix (B.M., 
I. 5392). A portion of a. carina (B.M., I. 13518), portions of two 
scuta (B.M., I. 13519, I. 18520), and portions of two terga (B.M., 
so 2T 0. 18522) ; ; all these are free from matrix. The whole of 
the material is silicified. 

Holotype.—The right scutum (Figs. 1a, 6). 

Horizon and Locality. — Albian, Upper Greensand : Blackdown, 
Devonshire. 

Description of Specimens.— Right scutum (Figs. 1a, 6; B.M., 1.13519) 
convex, valve thin, divided unequally by a ridge extending from the 
apex to the basi-lateral angle; occludent margin slightly convex ; 
basal margin nearly straight; basi-lateral angle blunt; tergo-lateral 
margin convex, and protuberant near the middle. The unequally- 
spaced surface-grooves, which represent the growth periods, are 
very slightly sinuous on the occludent portion; on the tergo- 
lateral portion they are sharply upturned, and on nearing the margin 
curve inwards towards the apex. Occludent margin (from apex to 
rostral angle) 7°5 mm., tergo-lateral margin (from apex to basi-lateral 
augle) 8mm., basal margin 5mm. 


a 


IPS EELE Withers—Pollicipes levis, Sby. el 


Left tergum (Fig. 2; B.M., I. 13521) sub-rhomboidal, slightly 
convex; a rounded ridge, steep on the carinal side, divides the valve 
into two unequal portions ; the carinal portion is somewhat depressed 
and in its widest portion is about two-thirds the width of the occludent 
portion; the occludent portion is again divided almost equally by an 
obscure ridge from the apex to the scutal margin, which is immediately 
followed by a wide groove, almost parallel to the occludent margin. 
The well-marked grooves, of which there are seven on the portion 
preserved, are straight on the carinal portion, and on the occludent 
portion are straight until they reach the inner edge of the wide groove, 
and thence are recurved until they reach the occludent margin, where 
they are more sharply curved towards the apex. 


Fie. Pa) 

la. Pollicipes imbricatus, Withers, sp. nov. External view of right scutum. 
Albian, Upper Greensand: Blackdown, Devonshire. B.M., I. 13519. 

1. Id. Inner surface of same. 

2. Id. External view of left tergum. B.M., I. 13621. 

3a, Id. External view of carina. B.M., I. 5392. 

36. Id. Side view of same. 

3c, Id. Transverse section of same at one-third from base. ll figures x 4 diam. 


Length 9 mm., greatest breadth 6 mm., length of occludent margin 
5°5mm., length of scutal margin 6°5 mm. 

Carina (Figs. 3a—c; B.M., I. 5392) almost straight, with thin walls, 
widening gradually from the apex, subcarinated, triangular in 
transverse section, about twice as wide as high; apex probably 
pointed; basal margin angular (about 92°). The only ornamentation 

DECADE VY.—VOL. VII.—NO. XI. 32 


498 Sie s&s Withers—Pollicipes levis, Sby. 


is the well-marked grooves, of which there are eleven on the portion 
preserved. 

Length 10:5 mm., greatest breadth 3°5 mm. 

Measurements.—As all the valves are slightly broken, it is impossible * 
to give accurate measurements, but those given probably err very 
little. The broken parts are indicated in the figures. 

Comparison with other Species.—The scutum of Pollicipes imbricatus 
agrees with that of P. elongatus, J. Steenstrup (1837), from the Upper 
Chalk (Danian) of Denmark, in its general outline, and in having the 
wide, regularly spaced, well-marked grooves about the same distance 
apart as the growth-lines of P. elongatus. It is distinguished from 
P. elongatus, among other characters, in the occludent portion of 
the valve being twice the width of the tergo-lateral portion. 
In P. elongatus the occludent and the tergo-lateral portions are the 
same width. The tergum of P. imbricatus is altogether different 
from that valve referred to P. elongatus, and therefore need not be 
discussed. The carina and tergum of P. imbricatus were considered 
by J. de C. Sowerby (1836, p. 340) to belong to his P. levis = 
P.ungus. The carina disagrees with that of P. unguis in being much 
narrower, straighter, more angular in transverse section, and in the 
presence of the well-marked grooves, which make a much more 
acute angle than do the growth-lines in P. wnguis. The tergum of 
P. imbricatus differs from that of P. wnguis mainly in having a much 
wider groove running parallel to the ocecludent margin, and about half 
the width of the occludent portion of the valve. The scutum of 
P. unguis differs in the general outline of the valve, which approaches 
an equilateral triangle, and consequently the apex is much more acute 
than in P. ¢mbricatus. The scutum of P. unguis is also much thicker, 
and has a deep pit for the adductor scutorum. 

There is little doubt that P. zmbricatus is closely allied to P. unguis, 
J. de C. Sowerby, and P. glaber, F. A. Roemer (1841, p. 104, pl. xvi, 
fig. 11). 

“The scutum of P. imbricatus is distinguished from all other scuta 
that I have seen, either of Pollicipes or Scalpellum, by the entire 
absence of any pit or depression for the adductor scutorum. 


Porticirres uneurs, J. de C. Sowerby. Figs. 4, 5. 


1836. Pollicipes unguwis, J. de C. Sowerby, Trans. Geol. Soc., ser. 11, vol. iv, p. 335, 
No Ser, 1a, B* 

1836, P. levis, J. de C. Sowerby, pag. cit., pl. xi, fig. 5. 

1845(?). P. ungwis, A. Reuss, Bohmischen Kreideformation, p. 17, pl. v, fig. 44. 

1850. P. wagwis, H. B. Geinitz, Das Quadersandsteingebirge, p. 100. 

1850. P. levis, H. B. Geinitz, ibid. 

TSI, 72h unguis, C. Darwin, Pal. Soc. Monogr. Foss. Lepadide, p. 64, pl. iv, fig. 1. 

1853. BP. unguis, C. Darwin, Ray Soc. Monogr. Sub-class Cirripedia, Synopsis et 
Index Systematicus, p. 637. 

1865. P. Megs. Salter & Woodward, Cat. and Chart. Foss. Crustacea, p. 27, pl. i 
fig. 


Uo 22 aan H. Woodward, B.M. Cat. Brit. Foss. Crustacea, p. 141. 
1886. P. unguis, J. Kafka, Sitz. Ber. k. Bohm. Gesell. Wiss. Sn Prag, 1885, p. 573. 
1887. P. wnguis, Fritsch & Kafka, Crust. Bohmischen Kreidef., p. 12. 

This common Gault species was founded by J. de C. Sowerby on 
a rostrum and one of the latera of the lower whorl. Darwin (1851, 


T. H. Withers—Pollicipes levis, Sby. 499 


p- 64, pl. iv, fig. 1) figured a number of valves belonging to a single 
individual, namely, a carina, a pair of terga, a rostrum, a sub-rostrum, 
a pair of upper latera, a pair of latera of the lower whorl from the 
carinal end of the capitulum, and two other latera of this same whorl 
from one side of the rostral end of the capitulum. These are preserved 
in the Museum of Practical Geology, Jermyn Street. Darwin says of 
the scutum: ‘‘ Although the scutum is, unfortunately, at present 
unknown, there can be scarcely any doubt that it would closely 
resemble that of P. glaber, and therefore I have not hesitated, in 
this instance, to break through my rule of exclusively taking the 
scutum as typical in Pollicipes: should, hereafter, a scutum be found 
in the Gault like that of P. glaber, it may, with considerable confidence, 
be named as belonging to this species.’’ 


Fic. 

4. Pollicipes unguis, J. de C. Sowerby. External view of the right side of part of 
a capitulum of a young individual. x 6diam. Albian, Gault: Folkestone, 
Kent. B.M., 1.13523. c. carina; s. scutum; ¢. tergum; /. upper latus ; 
¢./. carinal latus. 

5a. Id. External view of right scutum of a much older individual. x 2 diam. 

5b. Id. ue surface of same, showing the deep pit for the adductor scutorum 
muscle. 


In the British Museum (Natural History), registered I. 13523, 
there is a young example of P. wnguis, with several of the valves of 
the capitulum in position (Fig. 4). Theright side of the capitulum is 
uppermost, and shows the carina, scutum, tergum, upper latus, and 
cearinal latus. Its importance lies in the fact that the valves are almost 
in their original positions, and that it includes the scutum, which 
has not been described previously. The portion of the capitulum 
preserved is twice as long as wide. Its greatest length is 9mm. and 
its greatest breadth 4.5mm. With the exception of the scutum the 
various valves of P. wnguis have been fully described by Darwin, 
and in these circumstances it is proposed here to describe the 
scutum alone. 

The description of the external characters of the scutum is based 


500 T. H. Withers—Pollicipes levis, Sby. 


mainly on that valve seen in the young individual (Fig. 4) and on 
a much larger scutum of another individual (Figs. 5a, 6). The 
description and figure of the inner surface of the scutum is taken 
from the larger valve, now in my possession. 

Descr iption of Scutum.—General outline approaching an equate 
triangle, convex, moderately thick, divided into two unequal portions 
by a ridge extending from the apex to the basi-lateral angle, the 
occludent portion being about twice as wide as the tergo-lateral 
portion. A further ridge extends from the apex to about the middle 
of the basal margin, slightly nearer the rostral angle; basal margin 
almost straight, making with the occludent margin an angle of 
about 71°, and with the tergo-lateral margin an angle of about 
63°; occludent margin slightly convex; tergo-lateral margin pro- 
tuberant near the base, and incurved towards the apex; rostral angle 
sharp ; basi-lateral angle blunt. Surface of valve almost smooth, 
with fine longitudinal strize, which are more strongly marked in some 
specimens. The deep pit for the adductor scutorum takes up the 
whole of the lower two-thirds of the valve. From the top of this pit 
a depression runs to the apex. This depression, which is marked with 
fine oblique lines, extends on one side to the tergo-lateral margin, and 
on the other is bounded by the inner occludent margin, which is the 
same width the whole length of the valve. Length of occludent 
margin (from apex to rostral angle) 14mm., length of basal margin 
11:5 mm., length of tergo-lateral margin (from apex to basi-lateral 
angle) 15°5 mm. 

Horizon and Locality.—Albian, Gault: Folkestone, Kent. 

Comparison with other Species. — Darwin (1851, p. 67) says of 
P. unguis: ‘‘ As before remarked, this species is very closely related 
to the cretaceous P. glaber, of which it is evidently the representative 
in the Gault; the chief difference consisting in the more elongated 
form and greater size of its upper latera, which, in P. unguis, exceed 
half the length of the tergum, whereas in P. glaber they are only 
one-third of its length. The carina, in the present species, has its 
basal margin, perhaps, less pointed, and has a narrow linear channel 
along its edges; but I am not at all sure that this latter character does 
not vary. Lastly, the anterior lower latera in P. uwnguwis are thinner, 
and rather more convex, with the basal margin more arched and 
protuberant, with the external oblique ridge very much more central.” 
The scutum of P. wnguis, as expected by Darwin, is extremely like 
that of some forms of P. glaber, and apparently differs only in being 
much thicker. Some of the differences between the various valves of 
P. unguis and P. glaber given by Darwin are not apparent in some 
specimens. There is much variation in the valves of both species, and 
it is highly probable that some of the differences will eventually be 
correlated with the differences of horizon. Consequently, until a 
larger number of specimens of both species from definite horizons have 
been examined, it is not advisable to attempt to point out probable 
differences. P. wnguis is confined to the Gault, and P. glaber ranges 
right up into the Upper Senonian. 

My thanks are due to Dr. F. A. Bather, Mr. G. C. Crick, and 
Mr. C. P. Chatwin for help in connexion with this paper. 


i 


R. M. Deeley—Plasticity of Rocks. 501 


LIST OF WORKS REFERRED TO. 


Darwin, C. 1851. A Monograph on the Fossil Lepadide or Pedunculated 
Cirripedes of Great Britain: Paleontographical Society, London, pp. vi, 88, 
with 5 pls. 

Darwin, C. 1854. A Monograph on the Sub-class Cirripedia, the Balanide, 
Synopsis et Index Systematicus: Ray Soc., London, pp. 684, with 30 pls. 
Downes, W. 1880. ‘‘ Blackdown’: Rep. and Trans. Devon. Assoc., Xii, 

pp- 420-46. 

Downes, W. 1882. ‘The Zones of the Blackdown Beds and their Correlation 
with those at Haldon, with a List of the Fossils’’: Quart. Journ. Geol. Soc. 
London, xxxvilil, pp. 75-92. 

Fritscu, A.J. & Karka, J. 1887. Die Orustaceen der Bohmischen Kreideformation. 
Prag. 4to; pp. 53, 10 pls. col., text-illust. 

Gemnitz, H. B. 1849-50. Das Quadersandsteingebirge, oder Kreidegebirge im 
Deutschland. Freiburg. 8vo; pp. 1-96, pls. i-vi, 1849; pp. 97-292, 
pls. vii-xii, 1850. 

Karka, J. 1886. ‘ Péispévek ku poznani cirripedt éeského Otvaru kridového”’ : 
Sitz. Ber. k. Bohm. Ges. Wiss., Prag, 1885, pp. 554-81, pls. i-il. 

Reuss, A. 1845-6. Die Versteinerungen der Bohmischen Kreideformation. 
Stuttgart. 4to; Abth. i, pp. 1-58, pls. i-xiii, 1845; Abth. ii, pp. 1-140, 
pls. xiv-l, 1846. 

Rormer, F. A. 1840-1. Die Versteinerungen des Norddeutschen Kreidegebirges. 
Hannover. 4to; 1 Lief., pp. 48, pls. i-vii, 1840 ; 2 Lief., pp. 97, pls. vili-xvi, 
1841. : 

Satter, J. W. & Woopwarp, H. 1865. A Descriptive Catalogue of all the 
Genera and Species contained in the accompanying Chart of Fossil Crustacea, 
showing the range in time of the several Orders, with some recent types. 
London. 4to; pp. ii, 28, with pl. 

Sowerpy, J. de C. 1836. ‘‘Descriptive Notes respecting the Shells figured in 
Plates XI-XXIII”’ (pp. 835-48). Appendix Ato W. H. Fitton, ‘‘ Observations 
on some of the Strata between the Chalk and the Oxford Oolite in the South-East 
of England’’: Trans. Geol. Soc. London, ser. 11, iv, pp. 103-389, pls. xi—xxiil. 

Srrenstrup, J. 1837. ‘‘Om Forwerdenens Dyrarter af de tvende Familier 
Anatiferide (Gray) og Pollicipedide (Gray) ’’: Kroyer, Naturhistorisk Tidsskrift, 
i, pp. 858-66. 

Srzenstrup, J. 1839. ‘‘ Bidrag til Cirripedernes Historie i Fortid og Nutid.’’ 
Ferste Bidrag. Anatiferide og Pollicipedide fra Kridtperioden: Kroyer, 
Naturhistorisk Tidsskrift, ii, pp. 396-415, pl. v. 

Woopwarp, H. 1877. British Museum Catalogue of British Fossil Crustacea, 
with their Synonyms and the Range in Time of each Genus and Order. London. 
8yo; pp. x1, 155. 


V.—Tue Prasticiry ofr Rocks any Mountain Bouinpine. 
By R. M. Dzstry, M.Inst.C.E., F.G.S. 


RITISH geologists must have read Professor Coleman’s Address 
to the Geological Section of the British Association with great 
pleasure and interest. As Professor Coleman remarks, geology finds 
some of its most seductive problems in the neglected extremes of the 
earth’s history. Out of the apparent tangle of the ‘drifts’ and 
Archean Gneisses Canadian geologists are now evolving an orderly 
sequence which must exercise considerable influence upon the progress 
of geology in other lands. The seemingly unnatural conjunction of 
Pleistocene and Archzean, Professor Coleman states, has furnished the 
clue to certain puzzling problems of the Archean. 
During a trip from Regina to Winnipeg this summer I had the 
pleasure of riding at the end of a Canadian Northern train with 
a young railway engineer, and discussing with him the problems that 


502 R. M. Deeley—Plasticity of Rocks. 


have to be faced to keep the line in good condition during the winter. 
In many places the line passes over areas of waterlogged ground. 
During the winter the cold penetrates the earth and freezes this 
water to depths of 10 feet or more. The ice thus formed expands, 
raises the earth into domes and makes the road bed very irregular. 
It is the business of the engineer to see that these irregularities are 
made good by packing up the line, a troublesome task with the 
temperature many degrees below zero F. 

The ‘Canadian shield’ consists of a base of granite or gneiss rising 
into numerous domes which are somewhat irregularly scattered over 
the area. Upon them rest the Keewatin and newer rocks. After the 
deposition of the Keewatin Series the land rose and formed a great 
mountain system, which was afterwards almost completely destroyed 
by denudation. 

The rising of this mountain system seems to have been due to the 
heating up of portions of what are now known as the Laurentian 
granites, rather than to crushing or folding. We must regard the 
mountain ranges as floating upon the earth’s crust, their lightness 
being due either to their high temperature bases or small relative 
density. Crushing and folding, apart from the heating that may 
result from it, do not seem competent to alone form high mountain 
systems; for the folds would not cause a great rise of the surface— 
the mass would sink as do the sediments deposited upon a sea-bottom. 
It seems most reasonable to regard mountain ranges as being due to 
the high temperature of the deep-seated rocks causing an uplift by 
expansion, just as the railway track is lifted by the freezing of the 
water beneath. If this view be the correct one, then it follows that 
the disappearance of the mountain range must have been due to the 
cooling down of the Laurentian rocks beneath; for otherwise the 
mountain peaks would have risen as fast as they were denuded. 

Professor Coleman gives a very interesting explanation of the 
reason for the formation of the dome-shaped masses of granite and 
gneiss upon which the Keewatin rocks rest. He suggests that the 
lower rocks became plastic, that the Keewatin above was unequally 
heavy, and that the granite rose in domes where the lightest loads 
were situated. 

It must be admitted that the formation of great depressed areas, 
such as that of Lake Superior, is a difficulty. Here it is considered 
that the granite below became so fluid that it was ejected at the 
edges and allowed the area from beneath which it came to sink bodily. 
But if such be the case, how is it that this portion of the earth’s crust 
did not rise again? It may be that to some extent the explanation is 
that the deeper portions of the earth’s crust are plastic, not viscous. 
Plastic materials do not flow unless the stress exceeds some particular 
limit. A mountain range may therefore be stable although its height 
may be hundreds of feet greater or less than is warranted by the 
density of the crust at the spot. 

Professor Coleman recognizes that the weight of the ice which once 
rested on the ‘Canadian shield’ depressed it, and that since the ice 
melted away there has been arise of the area. He says these sinkings 
and risings must be accomplished by plastic flow outwards from 


G. C. Crick—Two Type-specimens of Ammonites. 503 


beneath the loaded area, and inwards towards the area relieved of its 
load. He rightly uses the word plastic here. And here is another 
contrast between the properties of the ice-sheets which played an 
important part in the formation of some Canadian deposits and the 
rocks themselves. The ice moved much as a truly viscous liquid 
would have done whilst the deep-seated rocks underwent plastic 
deformation. The ice formed and maintained an almost level upper 
surface like that of the Antarctic Plateau, whilst the plastic rocks 
allowed themselves to be cut into hill and dale until the stresses 
produced were sufficiently great to allow of plastic flow. Plastic 
solids never reach a condition in which the stresses are equal in all 
directions ; they cease to flow when the stress falls below some particular 
value. Although it is true that the solid, liquid, and gaseous states 
are continuous, the liquid differs from the plastic solid inasmuch as it 
yields to any stress however small, whereas the solid does not begin to 
deform continuously until the unbalanced stress reaches some particular 
value depending upon the nature of the material and the temperature. 
With rise of temperature this limiting stress becomes smaller and 
smaller, and when it falls to zero the solid becomes a liquid. For 
all practical purposes, however, substances which flow (shear) under 
very small stresses may be regarded as viscous (liquids). Professor 
Coleman shows that although the ‘ Canadian shield’ was depressed by 
the weight of the Pleistocene ice resting upon it, it has not risen as 
much as might have been expected considering the weight of ice 
melted away; probably this is also owing to the plastic nature of the 
earth’s crust. 

There is another interesting property of plastic substances which 
might be referred to. When a test bar of iron or steel is drawn out 
to some extent in a testing machine and its length then measured, it 
will be found that, after giving it a light blow, it will have shortened 
again somewhat. If the bar has suffered compression it will have 
lengthened again. In many cases it has been found that an earth- 
quake has resulted in a rise or fall of the land locally. May it be 
that the jar of the strained plastic crust has released strains in 
a similar manner and given rise to sudden change of form ? 


VI.—Nore on tHE TYPE-SPECIMENS OF AWMONITES CORDATUS AND 
AMMONITES EXCAVATUS, J. SOWERBY. 


By G. C. Crick, F.G.S., British Museum (Natural History).! 


SOWERBY’S type-specimens of Ammonites cordatus and 
» Ammonites excavatus have been dealt with comparatively 
recently by Miss M. Healey in the Palcontologia universalis (sér. 11, 
fasc. 1, August, 1905, Nos. 94, 94a, and 92, 92a, 926 respectively), 
but her statements require a little modification in some details. Both 
specimens are in the British Museum collection, and were described 
and figured in the Iineral Conchology. 
1. Ammonites cordatus.—Miss Healey gives the date of publication 
of this species as 1812, and observes that ‘‘ The date 1813 is given on 
the plate, but on the title page the date is 1812”. From this remark 


1 Published by permission of the Trustees of the British Museum. 


504 G. CO. Crick—Two Type-specimens of Ammonites. 


it is obvious that the date of publication of the species was taken from 
the title-page of vol. i, this bearing the date 1812. But, as is well 
known, the ILneral Conchology was issued in 113 numbers or parts, the 
first sixty-five parts being by James Sowerby, and the rest by his son, 
James de Carle Sowerby. Vol. i included Nos. i—xviii, which appeared 
between 1812' and August, 1815. The figures and description of 
Ammonites cordatus (pp. 51-2, pl. xvii, figs. 2 and 4) were published in 
No. iv, which is dated April 1, 1813, the same date appearing on the 
plate. It is obvious, therefore, that the date of publication of the 
species is not 1812, but 1813. 

Sowerby figured two specimens (figs. 2 and 4), but regarded the 
original of his fig. 2 as the type of his species; for, referring to 
the fossil represented in his fig. 4, he says: ‘‘I am much inclined to 
consider it as a distinct species.” The original of fig. 2 is therefore 
the holotype, and that of fig. 4 a paratype. Respecting the para- 
type Miss Healey states: ‘‘ The difference between the photograph of 
the paratype and the original figure [fig. 4] is striking, but there can 
be no doubt about its identity, as it bears a label on which is written 
in Sowerby’s handwriting (Ammonites cordatus, M.C. 17, fig. 2, 4) 
and the green wafer with which he marked figured specimens.” As 
will be seen from a comparison of Sowerby’s figure of the holotype 
with the photograph of the same given in the Palgontologia universalis, 
Sowerby’s figure is reversed; but it would seem from the figures of 
the paratype given on the same plate of the Palgontologia universalis 
that in this case Sowerby’s figure was not reversed. However, 
a careful examination of the paratype, especially of the septal surface 
at the anterior end of the specimen, shows that Sowerby’s figure, so 
far as the outer whorl is concerned, is reversed; and that the inner 
whorls have been drawn from the opposite side of the specimen. So 
far, then, as the outer whorl is concerned, the photograph reproduced 
in the Palontologia universalis represents the opposite side of the 
specimen to that figured in the Mineral Conchology, and, in a great 
measure, accounts for the striking differences between the figure in 
the Palgontologia universalis and Sowerby’s figure. Even if the 
specimen had not been labelled in Sowerby’s handwriting, there could 
be no doubt whatever about its identity, since the details of the septal 
surface at its anterior end have been carefully copied in Sowerby’s 
figure. 

2. Ammonites excavatus.—-Miss Healey gives the date of publication 
of this species as 1818. It is true that this is the date on the title- 
page of the volume (vol. ii) in which that species was described and 
figured (p. 5, pl. cv), but, as has been mentioned above, the Jhneral 
Conchology was published in numbers or parts; and vol. ii included 
Nos. xix—xxxv, which were issued between October 1, 1815, and 
June 1, 1818, both dates inclusive. The figure and description of 
Ammonites excavatus appeared in No. xix, which is dated October 1, 
1815. The date of publication of the species should therefore be 1815, 
and not 1818. 


1 The dedication of the work, and each plate in No. i, which included pls. i-iii 
with explanatory text, is dated May 25, 1812. 


| 
| 


fh. I. Pocock—Carboniferous Arachnida. 505 


There are considerable differences between Sowerby’s figure and 
the photograph of the type-specimen reproduced in the Palaontologia 
aniversalis (sér. 11, fasc. 1, No. 92a), but it should be mentioned that 
Sowerby’s figure, besides being reversed (as usual) and somewhat 
restored, represents the fossil without the natural internal cast of the 
body-chamber (which, as Sowerby himself observed, is separated from 
the rest of the shell), whilst in the photograph this portion of the 
fossil has been placed in its natural position. 


VII.—Nores on tort Morrnotocy anp Grnertc NomMENCLATURE OF 
SoME CARBONIFEROUS ARACHNIDA. 


By R. I. Pocock, F.L.8., F.Z.S. 
1. On ANTHRAQOMARTUS AND PROMYGALE. 


N his monograph of Paleozoic Arachnida published in 1904, 
Dr. Fritsch divides the order Araneze into two suborders—the 
Arthrarachne, Haase, containing the Arthrolycoside, and the 
Pleuraranes, Fritsch, containing the Hemiphrynide (Hemiphrynus) 
and the Promygalide (Promygale). 

Haase, Beecher, and others, whom Fritsch follows, were no doubt 
right in referring Arthrolycosa and allied genera to the order Aranee, 
but the Pleuraraneze are in my opinion nothing but Anthracomarti, 
the genus Promygale itself being synonymous with Anthracomartus. 
The form of the carapace and structure of the appendages are the same 
in the two. The constriction between the prosoma and opisthosoma 
occurs in both. The segmentation of the opisthosoma is similar in the 
two, even in the presence of a longitudinal sulcus dividing the pleural 
laminze into an external and an internal moiety, and in the angulation 
of the posterior border of the posterior sternal plates. 

Certain discrepancies in the figures published by Fritsch inevitably 
rouse a feeling of scepticism on the score of the accuracy of the 
restorations they represent. In Promygale bohemica (fig. 20) there are 
eight dorsal plates; each of the anterior seven is furnished with 
a divided pleural lamina, the posterior border of the eighth being 
produced in the middle line to form an unpaired plate. But in 
fig. 21, showing the ventral side, the last-mentioned plate is paired 
by a longitudinal sulcus. In P. elegans (fig. 26a, dorsal view), on the 
other hand, there are only seven dorsal plates. On the seventh the 
inner moieties of the pleural lamin are not shown, but on each side of 
the opisthosoma ten sclerites represent the outer moieties of these 
lamine. It is impossible to refer these with any certainty to their 
appropriate somites, and impossible to say which of the original seven 
pleural lamine have been subdivided to add to the number. A similar 
augmentation is shown in fig. 23, representing P. rotundata. This 
feature, if existent, should constitute a generic difference between 
P. bohemica on the one hand and P. elegans and P. rotundata on the 
other; but the drawings of the actual specimens of P. elegans (pl. xv, 
fig. 2) and of P. rotundata (text-fig. 24, p. 20) afford, so far as I can 
see, no support to the view that the pleural lamine are numerically 
in excess of the somites. On the contrary, there appears to be 
complete agreement between them in this particular. 


506 R. I. Pocock—Carboniferous Arachnida. 


Again, in the dorsal view of P. bohemica (text-fig. 20, p. 19), the 
outer moieties of the posterior four pairs of pleural lamine are 
marked with an additional concentric sulcus, which is continued 
across the unpaired lamina of the last tergal plate. This is no doubt 
the sulcus defining on the ventral side the outer plate of the lamin, 
which is present in all the well-preserved specimens of Anthracomartus 
that I have seen. 

One other difference, already referred to, between Promygale 
bohemica and the species of Anthracomartus is the presence in the 
former, to judge from the drawings, of an additional tergal plate, 
cut off by a sulcus from the posterior half of the seventh tergum, 
making eight of these plates visible on the dorsal side. Apart from 
the fact that this plate is not so divided, either in Hophrynus, 
Anthracosiro, or Anthracomartus, a fact sufficient in itself to cast 
doubts upon the reality of its segmentation in Promygale bohemica, it 
is noticeable that Fritsch himself omits the sulcus in question from 
his drawing of P. elegans (fig. 26, p. 21), and thus does not ascribe 
even a generic value to its presence in P. bohemica. Without further 
evidence I find it hard to believe in its existence. 

With regard to the restoration of the ventral side of the same 
species (text-fig. 21), since the posterior margins of the sterna are 
represented by dotted lines, it may be assumed that these plates were 
cracked and obliterated beyond the possibility of accurate decipherment. 
All the more remarkable, therefore, must be regarded the circumstance 
that the so-called comb-like organs are so well preserved as to admit of 
detailed restoration. I suggest that these alleged organs are really 
the two deep impressions which lie, one on each side, of the anterior 
sternal plates in Anthracomartus. The settlement of this question, 
however, must be left until an opportunity of examining the fossil has 
been afforded to some competent Arachnologist. 

Respecting the shape of the sternal plates as indicated on this 
drawing, it is noticeable that Fritsch has represented them by dotted 
lines running parallel with each other and at right angles to the 
longitudinal axis of the body, whereas the drawing of the original 
specimen of P. elegans (pl. xv, fig. 4) shows quite clearly that the 
sterna, at least in the posterior part of the body, are angularly 
curved in the middle line, exactly as in the examples of Anthracomartus 
that I have seen, thus establishing another point of similarity between 
this genus and Promygale. 

In referring the genus Promygale to the Aranez and Anthracomartus 
to the Opiliones, in spite of the striking similarity between them, 
Fritsch relies upon his alleged discovery of jointed appendages, 
representing the spinning mamille of the Aranez, upon the lower side 
of the opisthosoma in Promygale and their absence in Anthracomartus. 
In the restoration of P. elegans (text-fig. 26, B, p. 31) these 
appendages are shown as two pairs of slender three- or four-jointed 
limbs attached to the second and third sternal plates, each limb of 
a pair being widely separated from its fellow of the opposite side. 
I cannot think the drawings of the original specimens justify this 
conclusion. In fig. 3, pl. xv, showing the ventral side of P. elegans, the 
author has portrayed pieces of what he regards as small limbs scattered 


R. I. Pocock—Carboniferous Arachnida, 507 


without order, amongst other foreign bodies, over the exposed surface 
of the ventral side of the opisthosoma. Lach piece consists of three 
or four segments, but they differ from each other so greatly in length 
and thickness that no successful attempt can be made to pair or 
homologize them. Moreover, no clue is afforded as to their original 
situation, and it is permissible to suggest that perhaps after all they 
are not appendicular in nature but fragments of the sternal skeleton ; 
or indeed they may not belong to the organism at all like the so-called 
parasitic Spiroglyphs with which the fossil is strewn. And if appeal 
be made to fig. 4 on the same plate, representing the ventral side 
of another specimen, referred to the same species, and showing what 
might be interpreted as a pair of stout two-jointed limbs diverging 
from each other and from the middle line a little in front of the centre 
of the lower surface of the opisthosoma, it may be replied that, apart 
altogether from being in contact in the middle line, these segments 
bear no sort of resemblance to the restored opisthosomatic limbs 
depicted by Fritsch. I venture to suggest that, if appendicular in 
nature, the segments in question belong to one of the prosomatic 
appendages misplaced. But the angle they form coincides suspiciously 
with the angular curvature of the sterna of the mid region of. the 
opisthosoma in Anthracomartus. In the specimens of the latter genus 
that I have seen, as well as in Ammon’s drawing of A. palatinus, the 
borders of the sterna show up as angular ridges, the anterior and 
usually the strongest lying near the middle of the opisthosoma. 

With respect to the eyes, two pairs are represented in the restoration 
of Promygale bohemica; but the drawing of the original specimen 
shows only a single pair placed differently from either of the pairs 
outlined in the restoration. 

Since, then, critical examination of Fritsch’s drawings of Promygale 
fails to produce any trustworthy evidence that this genus can be 
separated from Anthracomartus, there is no choice but to regard the 
two as identical. 

As regards the Hemiphrynide, I have no doubt that these Arachnida 
must also be assigned to the Anthracomarti, since, so far as can be 
judged, they have the characters of that order. Most emphatically 
they do not belong to the order Aranee. The genus Hemiphrynus 
was based upon two species—JZ. longipes and H. hofmanni; but since 
these cannot be congeneric, if the restorations approach reality, 
I propose to select H. hofmanni as the type. 

The following features in Fritsch’s restoration of Anthracomartus 
call for comment (text-fig. 41, a dorsal, B ventral side). In the 
figure representing the dorsal side, the palpi (appendages of the 
second pair) show six segments with a terminal knob, projecting 
beneath the fore border of the carapace. The subequality in the 
length of the segments is quite unusual in the Arachnida, and if 
the terminal knob be a segment there is one segment in excess 
of the normal found in the class. The following four pairs of 
appendages consist of eight segments, including the coxe. This 
number also exceeds by one the normal found in Arachnida, the 
additional segment arising from the division of the femur. But 
in the first two pairs of these appendages the proximal segment 

& 


508 R. I. Pocock—Carboniferous Arachnida. 


of the femur is twice the length of the distal, whereas in the last 
two it is only one-third of the length. Since the femora are some- 
times segmented in the Chelonethi (Pseudoscorpiones), it would he 
rash to reject unhesitatingly on «@ priort grounds Fritsch’s restoration 
of the legs in Anthracomartus ; but since the legs of the specimens 
of the genus that I have seen, as well as of the allied genera 
Eophrynus and Anthracosiro, have normal and unsegmented femora 
like a great majority of the Arachnida, there can be very little 
doubt, I imagine, that Fritsch has mistaken fortuitous cracks for 
intersegmental joints. And this is by no means a solitary case 
where a knowledge of the constancy of certain morphological features 
in the Arachnida enforces the imposition of such an interpretation 
upon his restorations. 


2. On THE STRUCTURE AND CLASSIFICATION OF THE PHALANGIOTARBI. 


The name Phalangiotarbi was proposed by Haase in 1890 for 
a group accorded subordinal rank under the Opiliones. It contained 
the genus Phalangiotarbus created for the species described by 
Dr. Henry Woodward as Architarbus subovalis. I agree with Haase 
in thinking the type-species of Architarbus and Phalangiotarbus 
generically distinct, and with Fritsch in regarding them as belonging 
to the same order of Arachnida. But whereas Fritsch referred them to 
a family of Opiliones, the Architarbide, it appears to me necessary 
to give them higher systematic rank. I therefore retain the term 
Phalangiotarbi, leaving open for the moment the question of their 
right to inclusion in the Opiliones. In addition to the genera just 
mentioned I assign to this group Geratarbus, Geraphrynus, and the 
new genus Opiliotarbus described below. 

The morphology of this series of genera has hitherto baffled 
research ; and I am indebted to well-preserved material kindly lent 
to me by Dr. Wheelton Hind, Mr. 8. Priest, the late Mr. W. Madeley, 
Mr. H. Johnson, F.G.S., and Mr. Walter Egginton for the new inter- 
_ pretation of the facts set forth in the following pages. 

Since more than one species has in some cases been referred to the 
genera, I take this opportunity of stating that the type-species of 
each is as follows: Architarbus, Scudder, 1868; type, A. rotundatus, 
Seudder. Geraphrynus, Scudder, 1884; type, G. carbonarius, Scudder. 
Geratarbus, Scudder, 1890; type, now selected, G. dacoez, Scudder. 
Phalangiotarbus, Haase, 1890; type, Architarbus subovalis, H. Woodw. 
Opiliotarbus, nov.; type, Architarbus elongatus, Scudder. 

In the diagnosis of Geraphrynus published by Scudder in 1890, the 
genus is said to possess a ‘‘ posterior shield of the cephalothorax, the 
anterior triangular fragment of which slopes upwards to the ridge 
[of the cephalothorax ], while the hinder portions with their transverse 
scorings and ridgings lie on a plane below .. . this post-thoracic 
plate crowds down the middle of the six following segments”’. 

Comparing the dorsal and ventral views of my specimens of 
Geraphrynus with Scudder’s figure of G. carbonarius, I am forced to 
conclude that the so-called post-thoracic plate has no existence as 
such, but is composed of the anterior two or three sternal plates of 
the opisthosoma and the posterior projection of the carapace. It is 


Lt. I. Pocock—Carboniferous Arachnida. 509 


the latter area which ‘‘crowds down the middle of the six following 
segments’; the sternal plates are the anterior ‘‘ triangular fragment ”’ 
sloping upwards to the ridge as well as the ‘‘ hinder portions with 
transverse scorings and ridgings”’ that ‘‘lie on a plane below”’; and 
the median ridge is the sternal area of the prosoma. In a crushed 
specimen confusion might easily arise between these dorsal and 
ventral elements of the skeleton. 

This interpretation, if correct, disposes of Haase’s view of the 
morphology of Architarbus. This author modified Scudder’s drawing 
to suit his idea that Architarbus belongs to the Amblypygous Pedipalpi. 
The anterior part of Scudder’s post-thoracic plate he regarded as the 
posterior sternal plate of the prosoma and its posterior part as the 
genital plate of the opisthosoma. Scudder’s drawing, however, does 
not justify Haase’s rendering of it, full of ingenuity though his 
interpretation was. 

Commenting on Haase’s opinion, Hansen states that of the three 
specimens figured by Scudder as G. carbonarius ‘‘only one, the one 
figured on pl. xl, fig. 12, can with any certainty be classed amongst 
the Amblypygi’’; and in an explanatory foot-note he adds that the 
figure shows eleven distinct sternites of exactly the same shape as 
those of Phrynus. This statement, however, is not true. No Phrynus 
has four narrow sterna following and curving round the genital plate 
nor the posterior sterna so well defined and large as shown in Scudder’s 
figure. Hansen, moreover, ignores the existence of the plates in front 
of the backwardly bulging plate which, by implication, he takes for 
the genital operculum; and he is compelled to assume that the first 
pair of appendages exhibited by the fossil has been quite wrongly 
drawn. He seems, in fact, to trust to the accuracy of the drawing 
where it compares favourably, as he thinks, with a Phrynus, and 
assumes inaccuracy where the discrepancies are irreconcilable. The 
figure admittedly resembles a Phrynus superficially. So much so, 
indeed, that I feel sure the artist, Mr. H. Emerton, made use of 
a Phrynus to help his delineation ; and this supposition is borne out 
by certain discrepancies between Scudder’s description of the fossil 
and KEmerton’s figure of it. 

The difficulties, then, that have hindered the understanding of the 
skeletal morphology of these fossil Arachnida are due to confusion 
between the dorsal and ventral elements. It appears to me that in 
nearly all cases the dorsal surface is exposed; but that owing to the 
removal or crushing of the carapace the underlying coxe and sternal 
area of the prosoma and the anterior sternal plates of the opisthosoma 
are also shown. ‘The figures of the following species bear out this 
view: Architarbus rotundatus,' Geraphrynus carbonarius,? Geraturbus 
lacoet,® Phalangiotarbus subovalis.* 

Judging from the figures published by Fritsch and Scudder of the 
species they name Geraphrynus (or Architarbus) elongatus, and from 
the material I have examined, I am convinced that in this group the 


1 Geol. Survey, Illinois, 1868, p. 568. 

2 Mem. Bost. Soc. Nat. Hist., vol. iv, pl. xl, figs. 1, 10, 12. 

Spline, tig. Lie 

4 Gzou. Maa., Vol. IX, p. 885, 1872 (Ph. ‘ Architarbus’ subovalis, H. Woodw.). 


510 R. I. Pocock— Carboniferous Arachnida. 


carapace is large, unsegmented, and has either a straight or convex or 
considerably produced posterior border; at least, the coxe of the four 
posterior pairs of appendages are large and radiate from a central 
broader or narrower sternal area. The dorsal surface of the 
opisthosoma consists of five or six straight or curved but always 
short or very short anterior terga, and of three or four much longer 
posterior terga; and the ventral surface of seven, possibly eight, sternal 
plates, of which the posterior are long and the anterior short, the 
first being triangular and wedged between the coxe of the last 
pair of legs. ; 

The following notes on the genera above mentioned will explain my 
reasons for admitting them :— 

1. In Phalangiotarbus subovalis the anterior five terga of the 
opisthosoma are short and straight, and the posterior three large, there 
being eight in all. The posterior border of the carapace is straight, 
the anterior border widely rounded. The chief peculiarities of the 
genus, however, lie in the facts that the sternal area of the prosoma is 
large and oval and that the coxee of the legs of the first pair do not meet 
in the middle line beneath those of the palpi. Only one specimen of 
this genus has been discovered, and I judge of its character from the 
figure published by Dr. Woodward. 

2. Architarbus, represented by the single species rotundatus, has 
the carapace rounded in front and strongly produced in the middle 
line behind, with the anterior terga of the opisthosoma curved round 
its bulging area. There are nine terga in the opisthosoma, and they 
appear to increase progressively in length from before backwards, the 
anterior five or six being short. ‘The sternal area of the prosoma is 
small and subcircular, and round it radiate four pairs of coxee of the 
ambulatory limbs, those of the first pair meeting in the middle line 
and concealing the basal segments of the palpi. This species is only 
known to me from Scudder’s figure and description. 

3. Geraphrynus has the carapace angular in front and convex or 
produced behind. The opisthosoma has nine terga, the posterior three 
being much longer than the anterior six, two or more of which follow 
the curvature of the carapace. The sternal area of the prosoma is 
long and narrow, and the coxee of the legs of the first pair meet in 
the middle line and underlie those of the palpi, as in Architarbus. 
From the latter Geraphrynus seems to be separable by the anterior 
angulation of the carapace, the long and narrow sternal area of the 
opisthosoma, and the marked enlargement of the posterior three terga 
of the opisthosoma. When characterized in 1884' this genus was 
based upon a single species represented by a specimen from Mazon 
Creek, Illinois. In 1890 the species was redescribed by Scudder,’ 
several additional specimens being used for the purpose, but it is quite 
clear from the context that the example illustrated by fig. 10, pl. xl of 
the later work is the type. It is from the figure and description of 
this specimen and from examples of other species in my hands that the 
characters of the genus have been taken. Beyond recording my belief 


1 Proc. Amer. Acad. Arts & Sci., vol. xx, pp. 17-18. 
* Mem. Bost. Soc. Nat. Hist., vol. iv, pp. 446-7. 


: 
: 
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: 


R. I. Pocock—Carboniferous Arachnida. 511 


that the other specimens described by Scudder as G. carbonarius were 
correctly referred to the genus Geraphrynus, despite the opinion of 
Hansen, | have nothing further to say about them. I cannot find any 
characters to justify the separation of Madrachne, Melander,’ from 
Geraphrynus. 

4. Geratarbus was based upon two species, G. scaber and G'. lacoet, 
which apparently belong to different orders of Arachnida, G. scaber 
being probably one of the Ricinulei. I select G. lacoe, therefore, as the 
type. Judging from the figure and description of G. lacoei, it seems 
that the posterior border of the carapace in Geratarbus is straight; the 
opisthosoma has nine terga, of which the anterior five are short and 
straight from side to side and the posterior four much longer, gradually 
increasing in length from the sixth to the ninth, the ninth equalling 
the sum of the seventh and eighth. The sternal area of the prosoma 
is narrow and elongate, and the coxe of the first pair of legs meet 
only at their proximal ends and diverge at an acute angle. Geratarbus 
differs from Geraphrynus and Architarbus in the straightness of the 
posterior border of the carapace and of the anterior terga of the 
opisthosoma, in the difference in relative size of the posterior terga, 
and in the divergence of the anterior coxe. 

5. Opilotarbus, nov. Carapace evenly rounded in front, its postero- 
lateral angles squared, and its posterior border straight. Opisthosoma 
nearly parallel-sided, somewhat widely rounded at its anal extremity, 
with apparently the normal number of sterna but only eight terga, of 
which the anterior five are short and straight and the posterior three 
verylarge. Sternal area of prosoma small, oval, longer than wide. Coxe 
of legs of first pairin contact throughout. Type, Architarbus elongatus, 
Scudd.,? 1890, from Mazon Creek, Braidwood, [llinois. 

Fritsch * published figures and descriptions of what he believed to 
be the dorsal and ventral views of Scudder’s type of this species. 
So far as the dorsal surface is concerned this view is probably correct ; 
but it is perfectly clear that the figure of the ventral side, if 
approximately accurately drawn, was taken from another specimen. 
I have no doubt that it represents a species of Geraphrynus. Neither 
in its proportions nor in the position of its limbs ‘can it be made to 
agree with Emerton’s figure of the ventral view of the type or with 
Fritsch’s own figure of the dorsal view of the latter. 

Opiliotarbus has the posterior border of the carapace and the anterior 
terga of the opisthosoma straight as in Geratarbus, but it differs from 
that genus in having only eight terga on the opisthosoma, of which 
five are short and three very long. 

When the characters of the genera above described are analysed, 
it seems that Phalangiotarbus stands quite apart from the others in the 
large size of the sternal plate of the prosoma and the wide separation 
of the coxee of the legs of the first pair. For this reason I propose to 
-follow Haase and refer it to a distinct family, Phalangiotarbide. To 
comprise the rest the family name Architarbide is available. 

In the following key to the genera I have juxtaposed them 

1 Journ. Geol. Chicago, vol. xi, p. 179, pl. v, fig. 1, and pl. vil, fig. 1, 1903. 
2 Mem. Bost. Soc. Nat. Hist., vol. iv, p. 449, pl. xl, fig. 1 (ventral view). 
3 Pal. Arachn., pp. 33, 34, fig. 374 (dorsal view), not fig. 37B. 


512 Dr. J. W. Spencer—Discovery of Fossil Mammals in Cuba. 


according to my conception of their affinities based upon the figures 
and descriptions. If the latter are erroneous with respect to the 
distinctive particulars relied upon, Opiliotarbus and Geraphrynus will 
probably fall as synonyms of Geratarbus and Architarbus respectively. 


a. Sternal area of prosoma elliptical and wide ; cox: of legs of first pair not meeting 
in the middle line beneath those of the palpi; opisthosoma with eight terga, 
the anterior five short and straight, the posterior three long. 

Fam. PHALANGIoTARBID (Phalangiotarbus). 

a. Sternal area of prosoma quite narrow, generally linear; cox of legs of first pair 
meeting in the middle line beneath those of the palpi . Fam. ARcHITARBIDA. 

b. Posterior border of the carapace straight ; the anterior terga of the opisthosoma 
also straight. 
ec. Opisthosoma with only eight tergal plates, the sixth three times as long as 


the fifth and three times as wide as it islong . : . Opiliotarbus. 
c', Opisthosoma with nine tergal plates, the sixth twice as long as the fifth and 
five or six times as wide as it is long . .  Geratarbus. 


b'. Posterior border of the carapace evenly convex or considerably produced in the 
middle line; opisthosoma with nine tergal plates, of which at least the first 
and second are curved round the posterior border of tke carapace. 

d. Sternal area of the prosoma short and subcircular; terga ot the opisthosoma 
progressively increasing in length from before backwards . Architarbus. 
d'. Sternal area of the prosoma long and narrow; last three terga of the 
opisthosoma markedly longer than the others . . Geraphrynus. 


VIII.—Nore on rue Discovery By Proressor C. pE ta ToRRE oF 
Fossizr Mammats 1n Cusa. 


By Dr. J. W. Spencer, M.A., B.A.C., ete. 


T the recent meeting of the International Geological Congress 
in Stockholm, Professor C. de la Torre, of the University of 
Havana, made the announcement of a discovery of fossil mammals 
of Pleistocene age, in cavern deposits of Central Cuba. Hitherto the 
known fossil Vertebrates were few. Mr. T. W. Vaughan, in America, 
had published a long paper discrediting those previously reported, but 
before that time the late Professor E. D. Cope (America’s great 
Vertebrate Paleeontologist) had passed over the doubtful forms, and 
accepted especially one species of Edentate, supposing that other 
forms were buried and submerged during the subsequent depressions 
of the land. 

Professor de la Torre’s investigations have now established Cope’s 
hypothesis that many other fossil mammals occur in Cuba. Some 
of the specimens, representing half a dozen species of Rodents, 
Edentates, and other forms, were shown at Stockholm, while others 
are at the Central Port Museum, New York, under Professor Osborn. 

It may be added that the writer has also found the remains of 
Amblyrhiza (a Rodent as large as a deer) in a cavern on St. Martin, 
one of the north-eastern of the West Indian Islands—a notice of 
its occurrence in that island not having been published until the 
present time. 

Apart from the paleontological interest, the value of this great 
discovery of fossils lies in its confirmation of the recent connexion 
of the islands with the continent, and the late high continental 
elevation as shown in the ‘‘ Reconstruction of the Antillian Continent” 


Prof. T. G. Bonney—Glacial History of Western Europe. 518 


in 1895, previously reviewed in this Magazine. Similar evidence of 
great continental changes of level in Europe have been brought 
forward by Professor Edward Hull of this country, by Dr. Fridjof 
Nansen of Norway, and by others. 

Professor de la Torre’s investigations have also great interest in 
another field, for he has obtained a Jurassic fauna, which had been 
previously discovered, but later pronounced wanting in Cuba, by 
Mr. C. W. Hayes. Professor de la Torre is to be congratulated on his 
successful researches in geological problems of such great importance 
and of international interest which have a bearing on the question of 
cause of the Glacial period. 


NOTICES OF MEMOTRS. 
BE 
I.— British AssocIATION FOR THE ADVANCEMENT OF SCIENCE. 
SHEFFIELD, 1910. Appress by the Rev. Professor T. G. Bonney, 
Se.D., LL.D., F.R.S., President. 


(Concluded from the October Number, p. 469.) 


UCH, then, are the facts, which call for an interpretation. More 
than one has been proposed; but it will be well, before discussing ~ 
them, to arrive at some idea of the climate of these Islands during the 
colder part of the Glacial Epoch. Unless that were associated with 
very great changes in the distribution of sea and land in Northern and 
North-Western Europe, we may assume that neither the relative 
position of the isotherms nor the distribution of precipitation would 
be very materially altered. A general fall of temperature in the 
northern hemisphere might so weaken the warmer ocean current from 
the south-west that our coasts might be approached by a cold one 
from the opposite direction.t . . . I am doubtful whether we can 
attribute to changed currents a reduction in British temperatures of so 
much as 11°; but, if we did, this would amount to 28° from all 
causes, and give a temperature of 20° to 22° at sea-level in England 
during the coldest part of the Glacial Epoch. That is now found, 
roughly speaking, in Spitzbergen, which, since its mountains rise to 
much the same height, should give us a general idea of the condition 
of Britain in the olden time. 

What would then be the state of Scandinavia? Its present 
temperature ranges on the west coast from about 45° in the south to 
35° in the north. But this region must now be very much, possibly 
1800 feet, lower than it was in pre-Glacial, perhaps also in part of 
Glacial, times. If we added 5° for this to the original 15°, and 
allowed so much as 18° for the diversion of the warm current, the 
temperature of Scandinavia would range from 7° to —-3°, approximately 
that of Greenland northwards from Upernivik. But since the difference 
at the present day between Cape Farewell and Christiania (the one in 
an abnormally cold region, the other one correspondingly warm) is 

1 Facts relating to this subject will be found in Climate and Time, by J. Croll, 


1875, chs. ii and iii. Of course the air currents would also be affected, and perhaps 
diminish precipitation as the latitude increased. 


DECADE V.—VOL. VII.—NO. XI. 33 


514 . Professor T. G. Bonney— Presidential Address— 


only 7°, that allowance seems much too large, while without it 
Scandinavia would correspond in temperature with some part of that 
country from south of Upernivik to north of Frederikshaab. But if 
Christiania were not colder than Jakobshavn is now, or Britain than 
Spitzbergen, we are precluded from comparisons with the coasts of 
Baffin Bay or Victoria Land. 

Thus the ice-sheet from Scandinavia would probably be much 
greater than those generated in Britain. It would, however, find an 
obstacle to progress westwards, which cannot be ignored. If the bed 
of the North Sea became dry land, owing to a general rise of 600 feet, 
that would still be separated from Norway by a deep channel, 
extending from the Christiania Fjord round the coast northward. 
Even then this would be everywhere more than another 600 feet deep, 
and almost as wide as the Strait of Dover. The ice must cross this 
and afterwards be forced for more than 300 miles up a slope which, 
though gentle, would be in vertical height at least 600 feet. The 
task, if accomplished by thrust from behind, would be a heavy one, 
and, so far as | know, without a parallel at the present day; if the 
viscosity of the ice enabled it to flow, as has lately been urged,* we 
must be cautious in appealing to the great Antarctic barrier, because 
we now learn that more than half of it is only consolidated snow.’ 
Moreover, if the ice floated across that channel, the thickness of the 
boulder-bearing layers would be diminished by melting (as in Ross’s 
Barrier), and the more viscous the material the greater the tendency 
for these to be left behind by the overflow of the cleaner upper layers. 
If, however, the whole region became dry land, the Scandinavian 
glaciers would descend into a broad valley, considerably more than 
1200 feet deep, which would afford them an easy path to the Arctic 
Ocean, so that only a lateral overflow, inconsiderable in volume, could 
spread itself over the western plateau. An attempt to escape this 
difficulty has been made by assuming the existence of an independent 
centre of distribution for ice and boulders near the middle of the 
North Sea bed‘ (which would demand rather exceptional conditions 
of temperature and precipitation); but in such case either the 
Scandinavian ice would be fended off from England, or the boulders, 
prior to its advance, must have been dropped by floating ice on the 
neighbouring sea-floor. 

Tf, then, our own country were but little better than Spitzbergen 
as a producer of ice, and Scandinavia only surpassed Southern Green- 
land in having a rather heavier snowfall, what interpretation may we 
give to the glacial phenomena of Britain? Three have been proposed. 
One asserts that throughout the Glacial Epoch the British Isles 
generally stood at a higher level, so that the ice which almost buried 


1 R. M. Deeley, Grou. Mac., 1909, p. 239. 

2 BH. Shackleton, The Heart of the Antarctic, ii, 277. 

3 Tt has indeed been affirmed (Brogger, Om de sengiaciale og postglaciale nivaforand- 
ringer i Kristianiafelted, p. 682) that at the time of the great ice-sheet of Europe 


the sea-bottom must have been uplifted at least 8500 feet higher than at present. — 


This may be a ready explanation of the occurrence of certain dead shells in deep 
water, but, unless extremely local, it would revolutionize the drainage system of 
Central Europe. 

Grou. Mac., 1901, pp. 142, 187, 284, 332. 


: 
: 
{ 


Glacial History of Western Europe. 515 


them flowed out on to the beds of the North and Irish Seas. The 
boulder-clays represent its moraines. The stratified sands and gravels 
were deposited in lakes formed by the rivers which were dammed up 
by ice-sheets.1 A second interpretation recognizes the presence of 
glaciers in the mountain regions, but maintains that the land, at the 
outset rather above its present level, gradually sank beneath the sea, 
till the depth of water over the eastern coast of England was fully 
500 feet, and over the western nearly 1400 feet, from which depression 
it slowly recovered. By any such submergence Great Britain and 
Ireland would be broken up into a cluster of hilly isiands, between 
which the tide from an extended Atlantic would sweep eastwards 
twice a day, its currents running strong through the narrower sounds, 
while movements in the reverse direction at the ebb would be much 
less vigorous. The third interpretation, in some respects intermediate, 
was first advanced by the late Professor Carvill Lewis, who held that 
the peculiar boulder-clays and associated sands (such as those of East 
Anglia), which, as was then thought, were not found more than about 
450 feet above the present sea-level, had been deposited in a great 
freshwater lake, held up by the ice-sheets already mentioned and by 
an isthmus, which at that time occupied the place of the Strait of 
Dover. Thus, these deposits, though directly due to land-ice, were 
actually fluviatile or lacustrine. But this interpretation need not 
detain us. 


Each of the other two hypotheses involves grave difficulties. That 
of great confluent ice-sheets creeping over the British lowlands 
demands, as has been intimated, climatal conditions which are scarcely 
possible, and makes it hard to explain the sands and gravels, sometimes 
with regular alternate bedding, but more generally indicative of strong 
current action, which occur at various elevations to over 1300 feet 
above sea-level, and seem too widespread to have been formed either 
beneath an ice-sheet or in lakes held up by one; for the latter, if of 
any size, would speedily check the velocity of influent streams. 


Some authorities, however, attribute such magnitude to the ice- 
sheets radiating from Scandinavia that they depict them, at the time 
of maximum extension, as not only traversing the North Sea bed and 
trespassing upon the coast of England, but also radiating southward 
to overwhelm Denmark and Holland, to invade Northern Germany 
and Poland, to obliterate Hanover, Berlin, and Warsaw, and to stop 
but little short of Dresden and Cracow, while burying Russia on the 
east to within no great distance of the Volga and on the south to the 
neighbourhood of Kief. Their presence, however, so far as I can 
ascertain, is inferred from evidence* very similar to that which we 


1 See Warren Upham, Monogr. U.S. Geol. Survey, xxv, 1896. This explanation 
commends itself to the majority of British geologists as an explanation of the noted 
parallel roads of Glenroy, but it is premature to speak of it as ‘‘ conclusively shown” 
(Quart. Journ. Geol. Soc., vol. lviii, p. 473, 1902) until a fundamental difficulty which 
it presents has been discussed and removed. 

2 A valuable summary of it is given in The Great Ice Age, J. Geikie, chs. xxix, 
xxx, 1894. 


516 Professor T. G. Bonney—Presidential Address— 


have discussed in the British lowlands. That Scandinavia was at one 
time almost wholly buried beneath snow and ice is indubitable; it is 
equally so that at the outset the land stood above its present level, 
and that during the later stages of the Glacial Epoch parts, at any 
rate of Southern Norway, had sunk down to a maximum depth of 
800 feet. In Germany, however, erratics are scattered over its plain 
and stranded on the slopes of the Harz and Riesengebirge up to about 
1400 feet above sea-level. The glacial drifts of the lowlands some- 
times contain dislodged masses of neighbouring rocks like those at 
Cromer, and we read of other indications of ice action. I must, 
however, observe that since the glacial deposits of Moen, Warnemiinde, 
and Riigen often present not only close resemblances to those of our 
eastern counties but also very similar difficulties, it is not permissible 
to quote the one in support of the other, seeing that the origin of each 
is equally dubious. Given a sufficient ‘head’ of ice in northern 
regions, it might be possible to transfer the remains of organisms from 
the bed of the Irish Sea to Moel Tryfaen, Macclesfield, and Gloppa; 
but at the last-named, if not at the others, we must assume the 
existence of steadily alternating currents in the lakes in order to 
explain the corresponding bedding of the deposit. This, however, is 
not the only difficulty. The‘ Irish Sea glacier’ is supposed to have 
been composed of streams from Ireland, South-West Scotland, and the 
Lake District, of which the second furnished the dominant contingent ; 
the first-named not producing any direct effect on the western coast of 
Great Britain, and the third being made to feel its inferiority and 
‘* shouldered in upon the mainland”’. But evenif this ever happened, 
ought not the Welsh ice to have joined issue with the invaders a good 
many miles to the north of its own coast? Welsh boulders at any 
rate are common near the summit of Moel Tryfaen, and I have no 
hesitation in saying that the pebbles of riebeckite-rock, far from rare 
in its drifts, come from Mynydd Mawy, hardly half a league to the 
E.S.E., and not from Ailsa Crag. 


During the last few years, however, the lake-hypothesis of Carvill 
Lewis has been revived under a rather different form by some English 
advocates of land-ice. For instance, the former presence of ice- 
dammed lakes is supposed to be indicated in the upper parts of the 
Cleveland Hills by certain overflow channels. I may be allowed to 
observe that, though this view is the outcome of much acute observation 
and reasoning,’ it is wholly dependent upon the ice-barriers already 
mentioned, and that if they dissolve before the dry light of sceptical 
criticism the lakes will ‘‘leave not a rack behind”’. I must also 
confess that to my eyes the so-called ‘overflow channels’ much 
more closely resemble the remnants of ancient valley-systems, formed 
by only moderately rapid rivers, which have been isolated by the 
trespass of younger and more energetic streams, and they suggest that 
the main features of this picturesque upland were developed before 
rather than after the beginning of the Glacial Epoch. I think that 
even ‘Lake Pickering’, though it has become an accepted fact with 


1 Pp. F. Kendall, Quart. Journ. Geol. Soc., vol. lviii, p. 471, 1902. 


Glacial History of Western Europe. 617 


several geologists of high repute, can be more simply explained as 
a two-branched ‘valley of strike’, formed on the Kimeridge Clay, the 
eastern arm of which was beheaded, even in pre-Glacial times, by the 
sea. As to Lake Oxford,! I must confess myself still more sceptical. 


The submergence hypothesis assumes that, at the beginning of the 
Glacial Epoch, our Islands stood rather above their present level, and 
during it gradually subsided, on the west to a greater extent than on 
the east, till at last the movement was reversed, and they returned 
nearly to their former position. During most of this time glaciers 
came down to the sea from the more mountainous islands, and in 
winter an ice-foot formed upon the shore. This, on becoming 
detached, carried away boulders, beach pebbles, and finer detritus. 
Great quantities of the last also were swept by swollen streams 
into the estuaries and spread over the sea-bed by coast currents, 
settling down especially in the quiet depths of submerged valleys. 
Shore-ice in Arctic regions, as Colonel H. W. Feilden? has described, 
can striate stones and even the rock beneath it, and is able, on a sub- 
siding area, gradually to push boulders up to a higher level. In fact, 
the state of the British region in those ages would not have been 
unlike that still existing near the coasts of the Barents and Kara 
Seas. Over the submerged region southward, and in some cases more 
or less eastward, currents would be prevalent; though changes of 
wind would often affect the drift of the floating ice-rafts. But 
though the submergence hypothesis is obviously free from the serious 
difficulties which have been indicated in discussing the other one, 
gives a simple explanation of the presence of marine organisms, and 
accords with what can be proved to have occurred in Norway, 
Waigatz Island, Novaia Zemlya, on the Lower St. Lawrence, in 
Grinnell Land, and elsewhere, it undoubtedly involves others. One 
of them—the absence of shore terraces, caves, or other sea marks—is 
perhaps hardly so grave as is often thought to be. 


But other difficulties are far more grave. The thickness of the 
Chalky Boulder-clay alone, as has been stated, not unfrequently exceeds 
100 feet, and, though often much less, may have been reduced by 
denudation. This is an enormous amount to have been transported 
and distributed by floating ice. The materials also are not much 
more easily accounted for by this than by the other hypothesis. 
A continuous supply of well-worn chalk pebbles might indeed be kept 
up from a gradually rising or sinking beach, but it is difficult to see 
how, until the land had subsided for at least 200 feet, the Chalky 
Boulder-clay could be deposited in some of the East Anglian valleys 
or on the Leicestershire hills. That depression, however, would 
seriously diminish the area of exposed chalk in Lincolnshire and 
Yorkshire, and the double of it would almost drown that rock. Again, 
the East Anglian Boulder-clay, as we have said, frequently abounds in 
fragments and finer detritus from the Kimeridge and Oxford Clays. 


1 F. W. Harmer, Q.J.G.S., vol. Ixii, p. 470, 1907. 
2 Q.J.G.8., vol. xxxiy, p. 556, 1878. 


518 Prof. T. G. Bonney—Glacial History of Western Europe. 


But a large part of their cutcrop would disappear before the former 
submergence was completed. . . . The instances, also, of the 
transportation of boulders and smaller stones to higher levels, some- 
times large in amount, as in the transference of ‘brockram’ from 
outcrops near the bed of the Eden Valley to the level of Stainmoor 
Gap, seem to be too numerous to be readily explained by the uplifting 
action of shore-ice in a subsiding area. Such a process is possible, but 
we should anticipate it would be rather exceptional. 

Submergence also readily accounts for the above-named sands and 
gravels, but not quite so easily for their occurrence at such very 
different levels. . . . In other words, the sands and gravels, © 
presumably (often certainly) mid-Glacial, mantle, like the Upper 
Boulder-clay, over great irregularities of the surface, and are some- 
times found, as already stated, up to more than 1200 feet. Hither 
of these deposits may have followed the sea-line upwards or down- 
wards, but that explanation would almost compel us to suppose that 
the sand was deposited during the submergence and the upper clay 
during the emergence; so that, with the former material, the higher 
in position is the newer in time, and with the latter the reverse. 


The passing of the great Ice Age was not sudden, and glaciers may 
have lingered in our mountain regions when Paleolithic man hunted 
the mammoth in the valley of the Thames, or frequented the caves of 
Devon and Mendip. But of these times of transition before written 
history became possible, and of sundry interesting topics connected 
with the Ice Age itself—of its cause, date, and duration, whether it 
was persistent or interrupted by warmer episodes, and, if so, by what 
number, of how often it had already recurred in the history of the 
earth—I must, for obvious reasons, refrain from speaking, and content 
myself with having endeavoured to place before you the facts of 
which, in my opinion, we must take account in reconstructing the 
physical geography of Western Europe, and especially of our own 
country, during the Age of Ice. 

Not unnaturally you will expect a decision in favour of one or the 
other litigant after this long summing up. But I can only say that, 
in regard to the British Isles, the difficulties in either hypothesis 
appear so great that, while I consider those in the ‘land-ice’ hypothesis 
to be the more serious, I cannot, as yet, declare the other one to be 
satisfactorily established, and I think we shall be wiser in working 
on in the hope of clearing up some of the perplexities. I may add 
that, for these purposes, regions like the northern coasts of Russia and 
Siberia appear to me more promising than those in closer proximity to 
the North or South Magnetic Poles. This may seem a ‘“‘lame and 
impotent conclusion” to so long a disquisition, but there are stages in 
the development of a scientific idea when the best service we can do it 
is by attempting to separate facts from fancies, by demanding that 
difficulties should be frankly faced instead of bemg severely ignored, 
by insisting that the giving of a name cannot convert the imaginary 
into the real, and by remembering that if hypotheses yet on their trial 
are treated as axioms, the result will often bring disaster, like building 


Notices of Memoirs—Sherborn’s Index Animalium. 519 


a tower ona foundation of sand. To scrutinize, rather than to advocate 
any hypothesis, has been my aim throughout this address, and, if my 
efforts have been to some extent successful, I trust to be forgiven, 
though I may have trespassed on your patience and disappointed 
a legitimate expectation. 


IJ.—Inpex Grevervm Et Speciervm Animatium. Report of a Committee 

consisting of Dr. Henry Woopwarp (Chairman), Dr. F. A. Barner 

(Secretary), Dr. P. L. Sctatzr, Rev. T. R. R. Sressrne, Dr. W. E. 
Horie, Hon. Watrer Roruscuitp, and Lord Watsinenam.! 


ONTINUOUS and steady progress has been made by Mr. Davies 

Sherborn in the preparation of Volume II of this Index. Since 

the report for last year was sent in, Mr. Sherborn has dealt with the 

remainder of the separate works of authors whose names begin with C, 

and of these the various editions of Cuvier proved exceptionally long 

and tedious to analyse. Other works have also been dealt with as 
opportunity offered. 

Valuable assistance has been rendered by Mr. Hartley Durrant, who 
lent from Lord Walsingham’s library (presented to the Trustees of the 
British Museum) a fine copy of the extremely rare work by Billberg, 
Enumeratio Insectorum, 1820, which has been indexed and made 
available for reference. 

The slips, which are preserved in the British Museum (Natural 
History) by the kindness of the Trustees, are quite in order for those 
who wish to consult them, and are of exceptional value to anyone 
monographing a particular genus. 

Mr. Sherborn and Mr. H. O. N. Shaw have written a paper clearing 
up the difficulties surrounding Sowerby’s Conchological Illustrations 
and Gray’s Descriptive Catalogue of Shells,? and Mr. Sherborn 
himself has written on the dates of the parts of Burmeister’s Genera 
Insectorum, 1838—46.5 

Systematic and regular work on this Index is greatly encouraged 
by the friendly attitude of the Association, and the Committee, in 
recommending its own reappointment, earnestly ask the Association to 
continue this valuable help by a further grant of £100. 


III.—Ovrtines oF tHe Grotocy or Nortuern Nicerta. By Dr. J. D. 
Fatconer, M.A., F.G.S.* 


HE Protectorate of Northern Nigeria lies for the most part between 
Lake Chad and the confluence of the Rivers Niger and Benue, 

and comprises an area of about 255,700 square miles. Crystalline 
rocks are exposed over about half of this area, and among them two 
series have been recognized: (1) a series of hard, banded, and much 
granitized gneisses of an Archean type; (2) a series of quartzites, 


1 Read before the British Association Meeting, Sheffield, 1910 (Section D). 
2 Proc. Malac. Soc., September, 1909, pp. 331-40. 

3 Ann. Mag. Nat. Hist., January, 1910. 

* Read before the British Association Meeting, Sheffield, 1910 (Section C). 


520 Notices of Memoirs—Dr. J. D. Falconer on N. Nigeria. 


phyllites, schists, and gneisses of sedimentary origin with associated 
amphibolites, hornblende schists, and other more or less metamorphosed 
igneous rocks. The two series, which were probably originally 
unconformable, have been folded together along axes which are 
predominantly meridional in direction. They have also been pierced 
by numerous igneous intrusions, which are readily subdivided into an 
older and a younger group. The older group consists principally of 
granites, wholly or partially foliated, which have been affected to 
a varying extent by the forces which produced the metamorphism of 
the gneisses and schists. The members of the younger group are 
non-foliated, and include such types as tourmaline granite, riebeckite 
granite, augite syenite, augite diorite, and numerous associated 
dyke rocks. 

Rocks of Cretaceous age are found in the valleys of the Benue and 
the Gongola and in the angle between the two rivers. They are 
invariably gently folded and sometimes broken and faulted, and consist 
of a lower series of sandstones and grits, in part salt-bearing, and an 
upper series of limestones and shales, with numerous fossils of 
Turonian age. The post-Cretaceous rocks, which rest unconformably 
upon the Cretaceous Limestone, and are probably all of Eocene age, 
occur over three detached areas: (1) in Sokoto Province and the 
Niger Valley, (2) in Bauchi and Bornu, and (3) in Yola. The Sokoto 
Series, which contains marine intercalations yielding abundant Eocene 
fossils, is continuous southward with the sandstones, grits, and 
ironstones of the Niger Valley. The correlation of the sandstones, 
grits, and clays of Bauchi, Bornu, and Yola with the Eocene rocks of 
Sokoto and the Niger Valley is based partly upon lithological 
similarities and partly upon the absence of evidence of any extensive 
post-Eocene submergence of the Protectorate. 

Extensive fields of basaltic lava occur in Southern Bornu and on 
the borders of Bauchi and Nassarawa ; and numerous puys of trachyte, 
phonolite, olivine basalt, and nepheline basalt are distributed through- 
out Southern Bauchi, Muri, and Yola. The puys and lava-fields alike 
are the product of Tertiary volcanic activity. 

During the latter part of the Tertiary period there appear to have 
been repeated minor oscillations of the crust, which culminated in the 
elevation of the Bauchi plateau and the Nassarawa tableland, the 
depression of the Chad area, and the establishment of the present 
river system. 


IV.—Tse Occurrence or Marine Banps at Matrsy. By Ww. H. 
Dyson.! 


Wyre the sinking operations at Maltby the writer has located 
the stratigraphical position of the fossils found and has 
inspected the excavated debris day by day. Although all fossils 
have been collected, reference is only here made to the marine bands. 

Taking the top of the Barnsley Coal (2452ft. 2in. deep or 


1 Read before the British Association Meeting, Sheftield, 1910 (Section C). 


Ee 


Notices of Memoirs—W. H. Dyson—Maltby Coal-beds. 521 


2193 ft. 5in. below Ordnance datum) as a base-line, the lowest 
marine band, 8ft. 7in. thick, occurred 340ft. lin. above the 
Barnsley Coal, the section being 1 ft. 11in. of bastard cannel overlain 
by 6ft. 8in. of blackish bind with balls of pyrites, and contained the 
following fossils, mostly preserved in pyrites: Zingula miytiloides, 
? Posidoniella, Pterinopecten carbonarius, P. papyraceus, Scaldia 
carbonaria, Euphemus wurei, Macrocheilina sp., Glyphioceras sp., 
Celacanthus, ? Cheirodus, Megalichthys, Rhadinichthys  monensis, 
Fhizodopsis sauroides. Among these aecrochetlina was fairly 
abundant. 

The next bed occurred 564ft. lin. above the Barnsley Coal. 
The material was dark-blue bind with ironstone and small cank-balls, 
and the following forms were present : Lingula mytiloides, Orbiculotdea 
nitida, Myalina compressa, Straparollus sp., Huphemus urei, Naticopsis 
sp., Pleuronautilus costatus, Solenocheilus cyclostoma, Acanthodes, 
Cladodus, Cclacanthus, Megalichthys, Platysomus, Elonichthys or 
Acrolepis, Rhizodopsis. Among these Straparollus is new to the 
Middle Coal-measures. 

The next marine band, 20 ft. 0} in. thick, lies 708 ft. 102 in. above 
the Barnsley Coal, the section being 19 ft. 03 in. of dark greyish-blue 
shale with hard cank-balls, resting on 12 inches of argillaceous 
limestone. It contains an abundant fauna, including twenty-six 
genera and thirty-five species of invertebrates, all marine forms. 
Chonetes laguessiana, Lingula mytiloides, Orbiculoidea nitida, Productus 
anthrax, Ctenodonta levirostris, Myalina compressa, Nucula equalis, 
NV. gibbosa, N. luciniformis, Nuculana acuta, Posidoniella levis, 
P. sulcata, Pseudamusium anisotum, P. fibrillosum, Pterinopecten 
papyraceus, Scaldia carbonaria, Schizodus antiquus, Syncyclonema 
carboniferum, Euphemus dorbignyi, E. wurei, Loxonema acutum, 
L. ashtonense, L. sp., Rhaphistoma radians, Bellerophon sp., ? Dimorpho- 
ceras gilbertsoni, Ephippioceras clittellarium, Gastrioceras carbonarium, 
? Glyphioceras paucilobum, G. phillipsi, G. reticulatum, G. sp., 
Orthoceras asciculare, O. sulcatum = koninckianum, O. sp., Pleuro- 
nautilus costatus, Acanthodes, Celacanthus, Elonichthys, Listracanthus, 
Megalichthys, Platysomus, Rhizodopsis saurotdes. Among these 
Pseudamusium anisotum has not hitherto been found above the 
Carboniferous Limestone. Among the fish-remains Listracanthus 
should be noted. 

The highest bed occurs 1000 feet below the summit of the Middle 
Coal-measures and 1244+ feet above the Barnsley Coal. It is 
10 ft. 11 in. thick, consisting of grey bind with ironstone bands, of 
greasy appearance. The fauna is poor, but Goniatites are not 
uncommon. Lingula mytiloides, Orbiculoidea nitida, Myalina com- 
pressa, Nuculana acuta, ? Bellerophon sp., Glyphioceras phillipsi, G. sp., 
Orthoceras sp., Listracanthus, Megalichthys, Rhadinichthys monensis. 
Among the fish-remains Listracanthus is to be recorded. 

The writer is indebted to Dr. Wheelton Hind, F.G.S., and 
Dr. A. Smith Woodward, F.R.S., for examining and naming the 
fossils. 


522 Reviews—Sir EH. Ray Lankester on the Okapi. 


REVIEWS. 


I.—MonoarapH oF THE Oxapr—Arras. By Sir E. Ray Lanxester, 
K.C.B., M.A., D.Sc., F.R.S. Compiled with the assistance of 
W. G. Rivewoop, D.Sc. 48 plates. 4to. Printed by order of 
the Trustees. Price 25s. 


a CE its discovery some ten years ago, the Okapi has perhaps 
been the subject of more papers and memoirs than have ever 
been devoted to any Ungulate mammal not of actual econdmic 
importance. The circumstances of its discovery, its isolation from 
other living forms, and its near relationship to Pal@otragus and 
Samotherium of the Lower Pliocene of Greece have all excited 
general interest in it. An important addition to the publications 
referring to this animal has just been issued by the Trustees of 
the British Museum under the title A Monograph of the Okapi— 
Atlas. This volume consists of a series of forty-eight plates pre- 
pared under the direction of Sir E. Ray Lankester, in illustration 
of a complete account intended to be prepared by him. These 
illustrations are of especial value because they bring together figures 
of the skulls and skins of a considerable number of individuals, 
including not only those in the British Museum, but also several 
from foreign museums and private collections. One set of plates 
consists of a beautiful series of drawings of the skulls of a number 
of individuals, illustrating the great variability of this part of the 
skeleton and of the degree of ossification of the curious separate 
horn-cores or ossicones, which in one set of individuals are entirely 
absent. A number of other plates show some of the remarkable 
peculiarities in the structure of the vertebre, particularly in the 
cervical region, and finally some ten plates are devoted to demonstrating 
the extreme variability of the striping on the fore and hind legs, 
and incidentally prove the futility of naming new species on the 
evidence of such unstable characters. It is much to be regretted 
that, according to the preface, the volume of text relating to these 
plates will probably not be published: at the same time the recent 
publication of several important memoirs on the subject renders this 
omission less serious, and the detailed and careful descriptions of the 
plates prepared by Dr. W. G. Ridewood add greatly to the value of 
the volume and go far to reconcile us to the absence of the text. 
The plates are for the most part drawn by Miss G. M. Woodward and 
Mr. Gronvald. 


IJ.—orran Deposits. 


[ Alexandra Ivchenko’s papers (in Russian, with abstract in French) 
will be found, illustrated, in Khrishtafovich’s Hzheiodnika no Gheol. 
¢ Min. Rossii (Ann. géol. et min. Russie), xii, pp. 146-70, 1909. ] 


A GOOD deal has been written lately on Deserts in one form or 

another, and we think it may be interesting to give a résumé of 
the views of Alexandra Ivchenko (or as he transliterates his name 
into French, Iwtschenko) of Kiev. Mr. Ivchenko finds that the types 


a 


Reviews—A lex. Ivchenko on Afolian Deposits. 523 


of stratification in eolian deposits can be divided into ‘ barkhans’,' 
ripple-mark, diagonal with opposed dips, discordant parallelism with 
great differences in the dips, horizontal and vertical. These types 
occur both in sandy and dusty accumulations. One can observe in 
purely zolian deposits, strata due to insulation (limy, saline, or irony), 
to vegetation (earthy, clayey), or to wind; and these can be further 
subdivided. One can trace certain characteristics as one passes from 
the desert type of deposits to that of the edge of the desert and from 
that to the steppe. The loess of Turkestan is purely eolian, while 
that of Kiev is aquatic. Similarly, one can judge how different beds 
of other geological ages were formed; thus the red grits of Tartarian 
age were xolian, while the sands bordering the Dnieper were aquatic. 
It is necessary to distinguish the dusts of deserts formed from the 
denudation of local rocks from that formed from the denudation of 
the soils in depressions. In addition to ordinary winds the -action 
of whirlwinds can often be distinguished by the spiral or circular 
arrangement of the dust particles. Whirlwinds, too, have a certain 
influence in the formation of desert depressions. Gentle breezes 
blowing towards ridges do not seem to have much influence in elevating 
dust unless the escarpment is below 30. Erosion and denudation of 
accumulations of dust upon low slopes seem to be localized and do not 
have a general influence. ‘he dimensions of particles of desert dust 
transported by the wind diminish from the centre towards the margins 
of the desert: the dimensions of the dust of the soil, which are less 
mobile and less carried, diminish from the margins to the centre. The 
erains of sand have special characters in eolian and in aquatic deposits ; 
in the former they are characteristically triangular. The vertical 
separation of accumulations of dust or sand can, up to a certain point, 
be attributed to the existence of vertical stratification. Similar beds 
due to the resistance of wind pressure may be in part the result of 
pressure of the upper beds on the lower beds of such deposits. The 
first (due to resistance to the pressure of the wind) form the surface 
of the accumulation, and the second (due to compression) form the 
interior. 


T11.—Brier Notices. 


1. ‘‘ Les Cavernes ET LES RIVI=RES SOUTERRAINES DE LA BELGIQuE”’ 
is the title of a sumptuously illustrated work by E. van den Broeck, 
E. A. Martel, and K. Rahir, which has been published at Brussels in 
two volumes, 1910, illustrated by 26 plates and 435 text-figures. 
There is a total of 1857 pages, arranged in an extraordinary manner, 
as there are sundry interpolations independently paged in successive 
places in each volume, so that precise reference is rendered difficult. 

The subject is dealt with in special relation to the hydrology of the 
Devonian and Carboniferous Limestones, and the question of potable 
waters. 

The great purity of the Givetian Limestone in, the Devonian and of 
the Upper Visean Limestone in the Carboniferous has facilitated the 
corrosive action of water and led to the production of some of the more 


1 Semicircular continental dunes. 


524 Brief Notices. 


important caverns and subterranean watercourses. These features 
are to some extent naturally dependent on tectonic structure, but 
all points are duly discussed—the folds and fractures, the mineral 
composition of the limestones and dolomites, the organic remains, 
notably of coral and crinoid, and the various kinds of weathering. 
The different forms of caverns and grottoes, the stalactites and 
stalagmites, tufa, swallow-holes, and underground channels are fully 
described ; and the whole subject is illustrated by pictorial views and 
many charming vignettes, by diagrams, plans, geological maps, and 
geological sections, The living fauna and flora as well as Pleistocene 
and later organic remains receive attention, and there are abundant 
references to the literature. 


2. Tue ‘‘CEnozorc Mammat Horizons or Western Norte America” 
are dealt with by Professor H. F. Osborn (Bulletin 361, U.S. Geol. 
Survey), and Mr. W. D. Matthew contributes an appendix comprising 
faunal lists of the Tertiary mammalia of the West. Various 
mammalian zones are recognized, from the Polymastodon zone of 
the basal Eocene to the Zguus zone of the Pleistocene; and Professor 
Osborn concludes ‘‘ that North America promises to give us a nearly 
complete and unbroken history of the Tertiary in certain ancient 
regions, which are, after all, comparatively restricted’’. 


3. A ‘‘Descrrption oF New Carnivores FRoM THE MIocENE OF 
Western Nesraska’’ has been contributed by Mr. O. A. Peters to 
the Memoirs of the Carnegie Museum, Pittsburg, vol. iv, No. 5 
(undated). The forms include species of Daphenodon, Borocyon, 
Cynodesmus, and Tephrocyon, belonging to the Canide; and Paroligo- 
bunis, belonging to the Mustelide. 


4. Wr have received the first part of a work entitled ‘‘ GzrotociscHE 
CHARAKTERBILDER”’, edited by Dr. H. Stille, and comprising six 
beautiful illustrations, with descriptions, by E. Philippi, of ‘‘ Eisberge 
und Inlandeis in der Antarcktis”’ (Berlin, 1910). 


5. ‘*GEOLoGY IN RELATION To Crvitn Eneinrerine,”’ by Mr. Robert 
Boyle, Assoc.M.Inst.C.E., President of the Glasgow University 
Geological Society, has been published by John Smith ‘& Co., Glasgow, 
price is. It is a small work of 19 quarto pages, and contains brief 
practical suggestions on the relation between geology and constructive 
works such as roads, railways, bridges, docks, etc., as well as on water- 
supply. As the author remarks, ‘‘ Success or failure in an engineering 
scheme depends largely on geological conditions.’”” General remarks 
are also given on geology, field-work, and the use of maps and 
sections ; but it may be observed that it is not often that the geologist 
has to work out the true dip of strata by trigonometrical methods. 
The author devotes more space than appears necessary to igneous 
rocks and petrology, illustrating the subjects of road-metal, building- 
stone, etc., by microscopic sections. ‘These are matters that few 
engineers can deal with personally, and the advice of a specialist should 
be sought when necessary. 


6. Liverpoot Grotocicat Socrety.—In commemoration of the Jubilee 
of this Society, a small but interesting volume, A Retrospect of 


Brief Notices. 525 


Fifty Years’ Existence and Work, has been prepared by a former 
President, Mr. W. Hewitt, B.Sc. (Liverpool, C. Tinling & Co., 1910, 
pp. 117). The Society was founded on December 18, 1859, at 
a meeting held at the residence of G. H. Morton. An excellent 
portrait of him is given, and there are portraits also of C. Ricketts, 
T. Mellard Reade, and Joseph Lomas, as well as illustrations of the 
footprints of Cheirotherium and of the gypsum boulder of Great 
Crosby. An account of the work accomplished by the Society, a list 
of papers published in the Proceedings, and biographical notices of 
some past members are included in the volume. 


7. Correswotp Natvxratists’ Fretp Crvs.—The first part of vol. xvii 
of the Proceedings of this Club is sumptuously illustrated with 
twenty-one plates and a number of text-figures. Geological articles 
dominate. Among these is a sketch of ‘‘Some Glacial Features in 
Wales and probably in the Cotteswold Hills”, by Mr. L. Richardson, 
who gives an account of the prominent glacial phenomena in the 
region of Snowdon, and draws attention to glacial features in the 
Brecon Beacons and in the amphitheatral hollows of the Cotteswolds. 
The Rey. H. H. Winwood records a section of the White Lias (Upper 
Rhetic) at Saltford, near Bath. Mr. Richardson further contributes 
a detailed account of ‘‘ The Inferior Oolite and Contiguous Deposits of 
the South Cotteswolds”’. 


8. ‘‘Tuxr Votcanic Rocks or Vicrorta”’ formed the subject of the 
presidential address delivered by Professor E. W. Skeats in 1909 to 
Section C (Geology and Mineralogy) of the Australian Association for 
the Advancement of Science. 


9. GrotogicaL Survey or THE Transvaat.—‘‘ The Geology of the 
Country round Zeerust and Mafeking,” by Mr. A. L. Hall and 
Dr. W. A. Humphrey, 1910, is the title of an explanation of Sheets 
5 and 6 of the Survey Map of the Transvaal. The geological 
formations belong to the Dolomite and Pretoria Series, with intrusive 
and contemporaneous igneous rocks. The structure of the region, the 
drainage and water-supply, the Malmani goldfield, and the lead and 
zine deposits of the Marico are described. 


10. A WeatpeEn ANnoponrs.—In 1856 Beckles referred to 
‘“‘Anodon(?)” in his paper ‘‘On the Lowest Strata of the Cliffs at 
Hastings” (Q.J.G.S., vol. xii, 1856, pp. 291, 292), a mixture of shells 
some of which are obviously Unios. Mr. R. B. Newton (Proc. Malac. 
Soc., vol. ix, June, 1910, pt. ii, p. 114) has now gone carefully into 
the subject and finds that an undoubted Anodonta does occur in 
the Wealden beds along with the various Unios so often met with. 
He figures and describes a beautiful specimen of the fossil, which 
he calls 4. Becklest, from the Fairlight Clays of Hastings. This forms 
part of the Rufford Collection now in the British Museum, and seems 
to be the oldest known true Anodonta yet described. 


11. Groroercan Survey or Eeypr.—A Report on ‘“‘ The Building 
Stones of Cairo Neighbourhood and Upper Egypt”’, by Dr. W. F. Hume, 
Director, is issued as Survey Department Paper, No. 16, 1910. It 
comprises full particulars of the white and yellow nummulitic 


526 Correspondence—W. B. Wright. 


limestones that are quarried at Gebel Moqattam to the south-east of 
Cairo and elsewhere ; some detailed quarry records are given on the 
authority of the late T. Barron, and a report on the chalky nummulitiec 
limestones used as building stone in Upper Egypt is contributed 
by Mr. H. J. L. Beadnell. There are also notes on sand-lime bricks, 
portland cement, etc. 


CORRESPONDENCE. 


ORIGIN OF THE BRITISH TRIAS. 


Srr,—In the October number of this Magazine Mr. A. R. Horwood 
has given us a summary of the conclusions he has come to as a result 
of his researches into the origin of the British Trias. The paper as 
printed, being only an abstract of a longer paper read at the British 
Association, has no doubt suffered much in clearness as a result of 
condensation. In its present form, however, it is unsatisfactory, being 
composed in part of facts long known and now put forward none too 
clearly and by no means for the first time, and in part of more or less 
new statements requiring substantiation. I feel, and I daresay I voice 
the feelings of other readers too, that I should now like to hear the 
evidence on which some of these last-mentioned statements are based. 
I do not wish for the present to be understood as criticizing the 
conclusions, but merely as asking for a more explicit statement of the 
facts. I will take the points under Mr. Horwood’s own numbers. 

(3) If there is a general absence of delta bedding in the Bunter 
[see (9)], what then is the evidence that it is a delta? Is it its 
dactyloid form (6), and, if so, is this capable of being demonstrated on 
a map ? 

(9) Apart from the fact that beds which should theoretically have 
lain at 40° now lie horizontal, is there any other evidence of tilting 
through an angle of 45° in any part of the Trias? 

(16) I am not very clear as to the author’s meaning here, but 
I presume it is that the signs of wind erosion are confined to one level 
on the syenites and other older rocks. I would now ask how many 
cases of this wind erosion are known and to what extent they can be 
demonstrated to occur only at one horizon in the marls; also whether 
the opportunities for their observation are not very exceptional ? 

(20) What is the evidence that the supposed Bunter river came 
from North-West Scotland? Jam aware that I may be displaying 
great ignorance of the literature of the subject in asking this question, 
but in that case a reference will set me right. 

(21) What are the points of petrographical correspondence between 
the Bunter, Keuper, and modern delta formations? What bearing on 
this question has the immediately following statement that ‘the 
Leicestershire Trias shows signs of chemical action, the Nile delta of 
mechanical ’”’ ? 

W. B. Wricur. 


DvuBLIN. 


Correspondence—H. Woodward. 527 


POLLICIPES FROM THE TRIMMINGHAM CHALK: A CORRECTION. 

In the Gzxotocican Macazinr for August, 1906, I described 
a number of species of Cirripedes mostly from the Norfolk coast. 
Amongst these I recorded and figured two valves from Mr. Brydone’s 
Collection (op. cit., p. 348) under the name of Pollicipes concinna. 
The specific name P. concinnus was used by Darwin more than fifty 
years previously in his Monograph on the fossil Lepadide (Pal. Soc., 
1851, p. 50, pl. i, fig. 1) for an Oxford Clay species. I regret 
my carelessness, and apologize for having neglected to correct it 
earlier. . 

I now propose to designate these specimens from the Trimmingham 
Chalk Bluff as Pollicipes corrugatus. 

Henry Woopwarp. 


O33 OPA Eup 


JOHN WILLIS CLARK, M.A., F.S.A. 
Born June 24, 1833. Dizrp OctroBer 10, 1910. 


Ws regret to record the death of Mr. J. W. Clark, Registrar of the 
University of Cambridge, and formerly Superintendent of the University 
Museum of Zoology and Comparative Anatomy. A versatile man 
who rendered distinguished service to Art, Literature, and Science, 
Mr. Clark was endowed with a personality that brought him many 
friends. To geologists he was known as chief author (with Professor 
T. McKenny Hughes) of the fascinating Life and Letters of the 
Reverend Adam Sedgwick (2 vols., 1890); and as he remarked in the 
preface, ‘‘ No task could have been more congenial to me.” 


MISCHLUANHOUS. 


_Norwicn Castru Museum: New Curaror apporntep.—In March 
last (Got. Mac., pp. 141-3) we noticed this excellent Museum and 
made special reference to its Curator, Mr. James Reeve, F.G.S., who 
had held office for more than fifty years, and sought retirement. 
Mr. Reeve was appointed ‘‘ Consulting Curator of the Museum’’, and 
the salary of Mr. Frank Leney, the Assistant Curator, was raised, but the 
post of Curator was not filled up at that time. On September 21 
the Council met under the presidency of the Lord Mayor, who moved 
that, as recommended by the Castle Museum Committee, Mr. Frank 
Leney, the present Assistant Curator, be appointed Curator, at an 
annual salary of £250. The Lord Mayor, who was seconded by 
Mr. Wild, said the Committee were unanimous in this recommenda- 
tion. Mr. Leney had held the post of Assistant Curator for ten years, 
and they were all agreed that it was for the benefit of the city and of 
the museum that the appointment should be made. The motion was 
then carried nem. con. 


528 Miscellaneous. 


AWARD OF THE Keith Gotp Merpat or tHE Royat Socrery or 
Epinzurex To Dr. Wueetton Hinp, F.R.C.S., F.G.S.—At a meeting 
of the Royal Society of Edinburgh on July 18 last, under the 
presidency of Dr. R. H. Traquair, the Keith Gold Medal was presented 
to Dr. Wheelton Hind for a paper on ‘‘The Lamellibranch and 
Gasteropod Fauna of the Millstone Grit of Scotland”. The fossils, - 
said Dr. Traquair, forming the subject of this research were placed in 
the hands of Dr. Hind for determination by the Geological Survey. 
They were found by Mr. Tait in certain marine bands in the basal 
portion of the Millstone Grit, charged with Lamellibranchs, 
Brachiopods, and Gasteropods, and associated with Lower Carboniferous 
species of plants. They have been collected from the counties of 
Midlothian, West Lothian, Lanark, and Stirling, their horizon being 
not far below the line which has been drawn between the Upper and 
Lower Carboniferous floras in accordance with the determinations 
of Dr. Kidston. The remarkable feature of this research is the 
recognition in the Scottish collection of a Lamellibranch fauna, of 
which quite 50 per cent. of the species are new to Europe, and which 
closely resembles the Lamellibranch fauna of the Coal-measures of 
Nebraska and Illinois in North America. The most striking member 
of the fauna is the shell Prothyris elegans, Meek, this being the first 
occurrence of the genus in the Carboniferous rocks of Great Britain. 
Dr. Hind’s researches show that it is impossible to distinguish any 
characters sufficient to separate the Scottish and American species 
from each other. He has demonstrated that the Gasteropods in 
this collection bear a strong relation to those of North America, 
several species being regarded as identical. He has also noted 
that the Brachiopods belong to a late period of Carboniferous time. 
In addition to his valuable researches in the Molluscan fauna of the 
Carboniferous Series in Great Britain, Dr. Wheelton Hind, who has 
been a Volunteer officer for many years, was two years since asked to 
raise a Battery of heavy artillery for the Territorials. This he 
succeeded in doing, and under command of Major Wheelton Hind on 
Dartmoor his company this year carried off the King’s prize for heavy 
batteries, both for firing and drill. 


Swiney Lecrurrs on Grotogy.—A course of twelve lectures will 
be delivered by T. J. Jehu, M.A., M.D., F.R.S.E., on the Coasts of 
Great Britain and Ireland, in the Lecture Theatre of the Victoria 
and Albert Museum, South Kensington, on Mondays and Tuesdays 
at 5 p.m. and Saturdays at 3 p.m., beginning on Saturday, 
November 5, at 3 o’clock. The lectures will be illustrated by 
lantern slides, and admission to the course will be free. Lecture I. 
Introductory. II. Recent Changes in the Relative Levels of Land 
and Sea. III. Movements of the Sea—The Foreshore. IV. The 
Coastline. V. Erosion and Accretion. VI. Sands and Sand-dunes. 
VII. The Fauna and Flora of the Coastline. VIII. The Coast 
of Scotland. IX. The East Coast of England (Tweed to Thames). 
X. The South Coast of England (Thames to Cornwall). XI. The 
Coast of the West of England and Wales. XII. The Coast of 
Ireland. 


‘No. 558, Ss a ‘Decade V.—Vol. VII.—No. XII. Price 2s. net. 


THE 


GEOLOGICAL MAGAZINE 


OR 


Slonthly Journal of Geologn. 


WITH WHICH IS INCORPORATED 


THEH GHOLOGIST. 


EDITED BY 


HENRY WOODWARD, LL.D., F.R.S., F.G.S., &c. 


ASSISTED BY 


Prorressor J. W. GREGORY, D.Sc., F.R.S., F.G.S. 
Dr. GEORGE J. HINDE, F.R.S., F.G.S, 
Sir THOMAS H. HOLLAND, K.C.I.E, A.R.C.s., D.Sc., F.R.S., F.GS. - 
Proressorn W. W. WATTS, Sc.D., M.Sc., F.B.S., V.P.G.S. 

“Dr. ARTHUR SMITH WOODWARD, F.R.S., F.L.S., 
HORACE B, WOODWARD, F.R.S., 


Src. Grou.Soc., AND 


ERGES: 


wy 


DECEMBER, 1910. 


© OWN awe sS: 


I. OxternaL ARTICLES. Page II. Reviews. Page 
The Foliated and non-Foliated Rocks British Museum Catalogue: Marine 
of Southern Nigeria. By Joun Reptiles of Oxford Clay. By 
Parkinson, M. ey IDCs in oae ode OLY) C. W. Andrews, D.Sc., F.R.S. ... 564 
Drift at Bostall Common, Plumstead. Memoirs of Geological Survey: Geology 
By R. H. CHANDLER. (With a of the London District. a Heeacs 
Section in text.) .. . 5384 B. Woodward, F.R.S. . . 567 
The Great Oolite Section at Groves? Introduction to Petrology. “By F.P. 
Quarry, Milton, Oxfordshire. By Mennell, F.G.S. ... 570 
L. RIcHARDSON, F.R.S.E.,F.G.8. 537 | Some New "Geological Maps : (1 ) Map 
|  Post-Pleistocene Flora and Fauna of of Egypt, by ‘Dr. W. F. Hume; 
Central England. By A. R. (2) Oxford Wall Maps... ... ... 571 
| Horwoop, Leicester Museum ... 542 rc 
The Residual Earths of British Guiana Gq oe Reroute yee PuoceEpixos. 
termed ‘Laterite’. By Professor eological Society of London— 
Tponibe Harrison, C.M.G., M.A., November io). LOL ODay Ge sccuaecee Gee OWe 
¥.G.S., F.1.C., assisted by K. D. IV. CorrEsponDENCE. 
Rew. (Coneluded.) ... doen IAs RitlOryoode sta true skis aoe ae 
Classification of the Lower Carboni- 
ferous Rocks. By Cosmo Jouns, Ve Oniruana, ) See ees 
MEM... F.G.S... ... ...° -.. 562 | John Roche Dakyns, et ae 575 


With this Number is presented an Extra Sheet, containing dex’ raid Title for 
Decade V, Vol. VII, 1910. EO 


LONDON: DULAU & CO., Lr., 37 SOHO auxin, W: 


em The Volume for 1910 of the GEOLOGICAL MAGAZIN oS 
price 26s. net. Cloth Cases for Binding may be had, price 1s. 6d. net. 


ROBERT F. DAMON, — 
WEYMOUTH, ENGLAND, a 


_ Begs to call the attention of Directors of Museums 
and Professors of Biology and Geology in Universities | — 
to his fine series of | 


Coloured Casts and Models 


Rare and Interesting Fossils. 


This interesting and attractive series will form a most 
valuable addition to any Museum of Zoology or 
Comparative Anatomy, and cannot fail to prove of 
the greatest interest alike to men of Science and to all 
Students of Natural History as well as to the general 
body of educated visitors to a public collection. 


A town about to establish a Museum would find that these 
specimens, when properly mounted and displayed in glass cases, 
with instructive labels to each, would form a substantial basis for 
a Public Museum at a very small cost. 

Directors or Curators and Professors of Colleges can obtain by 
return of post a full detailed list, and also, if desired, a list of the i 
Museums in Great Britain, Australia, Africa, America, Austria, | 
Belgium, Brazil, Canada, Denmark, France, Germany, Greece, ; 
Holland, India, Italy, Japan, New Zealand, Norway, Portugal, : 
Russia, and Switzerland, where these Casts may be seen which j 
have been supplied by him. 


To prevent delay and disappointment R. F. D. would be greatly 
obliged if intending purchasers would give him ample time to 
execute orders. 


THE 


GEOLOGICAL MAGAZINE. 


MEW SERIES) DECADENV.” VOle Vil 


No. XII.— DECEMBER, 1910. 


ORIG EIN AL ARErteEhmS- 


I.—Tue ReLaTion BETWEEN THE FOLIATED AND NON-FOoLIATED Rocks 
oF SourHERN Nierrta, West Coast, AFrica. 


By Joun Parkinson, M.A., F.G.S. 


CONTRIBUTION by Messrs. Horwood & Wade’ to the 

GeotocicaL Macazinr for November, 1909, calls attention 

(p. 505) to certain papers by me on the relation between the gneisses 
and schists and the later granites of Southern Nigeria. 

Since these papers were published in 1907 I have had the 
opportunity of visiting the western parts of Liberia, a considerable 
proportion of the littoral of the Gold Coast Colony, and on two 
occasions have spent some time in Southern Nigeria. These 
expeditions have served to impress upon me the close resemblance 
existing between the crystalline rocks of these widely scattered 
regions, a resemblance so marked as to suggest a common origin. 
The following notes on the petrology of the Oban Hills in Southern 
Nigeria may throw some light on the relation between the schists, 
the gneisses, and the granites of this part of West Africa. 

A study of the crystalline axis of the Oban Hills shows that, while 
the rocks may be conveniently grouped under certain heads, yet this 
arrangement must remain largely an artificial one. Acid ortho- 
gneisses occupy by far the greater portion of the central part of the 
area, and are, as it were, represented or replaced by a number of 
granite bosses westward in the neighbourhood of the Iyangita, an 
important tributary of the Calabar River. A short investigation 
shows that the gneisses include a variety of types, the mutual 
relations of which prove that they differ in age the one from the 
other to at least some extent. I have grouped these together into 
a single series: firstly, on account of their general petrographical 
similarity; secondly; on account of similarity in habit, e.g. the 
frequent occurrence of a streaky or of a banded structure; and, 
thirdly, on account of the occurrence of special but widely distributed 
petrological types, e.g. a garnet-granulite. 

In addition, comparison of a suite of specimens in the field shows 
that rocks petrographically granites pass by insensible gradations into 
these gneisses. Whatever the agent which produced the foliation 
in the one, it was clearly non-operative during the solidification of 


1 “The Old Granites of Africa.’’ 
DECADE V.—VOL. VII.—NO. XII. 34 


930 J. Parkinson—Foliated and non-Foliated Rocks, 


that part of the series represented by the other. In some localities 
no hard and fast line can be drawn between a series of specimens 
which, taken individually, exhibit many differences, and which have 
been collected over a distance to be measured only by a few yards. 
Distinctly later, though the difference in age need not, geologically, 
be very great, are the granites of the Iyangita, of Itara, and numerous 
other localities, where now and again we may see these rocks clearly 
intrusive into the Gneissose Series. To work back a stage in the 
geological sequence we must appeal to the schists of the Calabar 
River at the Ekankpa Ford, south-east of Isbofia, of the Kwa River 
at Abuton, and of the Akpa Iyefe.’ In each locality (and the three 
given could be supplemented by others from the eastern and north- 
eastern parts of the hills) is a well-marked group of mica- and 
hornblende-schists, associated with granulites, and riddled by acid 
intrusions. In the first and second a banded gneiss is produced by 
a kind of lt-par-lt injection; in the last the dissemination of the 
acid magma was irregular. In regard to the nature of the intrusions, 
the first is now a granitic gneiss; the second a granitic gneiss associated 
with a coarser rock of pegmatoidal habit; in the third, the rock is 
practically a pegmatite. To these petrographical types the remainder 
of the district affords many resemblances, amounting often to identities. . 
Pegmatites crushed and uncrushed are distributed sporadically, but 
far from uncommonly, over the entire area, carrying tourmaline, 
garnet, and muscovite as accessory minerals; here and there, e.g. near 
Netim, Awi, Aking, Awdfong, and Mkpot, mica- and hornblende- 
schists appear, petrographically to be correlated with those of Abuton 
and the Akpa Iyefe. 

The typical mzca-schists of the Akpa Iyefe on the Kamerun frontier 
are rather massive rocks, not conspicuously laminated, and with 
a tendency to become gneissose. On applying a low-power hand- 
lens quartz and felspar become apparent, although crystals of either 
mineral are here and there discernible to the naked eye. In some 
specimens an indication of banding is noticeable. The attempt at 
a gneissose structure in the schists is obvious in many places, and is 
of interest in relation to the very close association they have to the 
intrusive granite. Possibly the structure is due to material which 
permeated from the acid magma, as I have suggested elsewhere * in 
referring to the work of Lacroix and others. 

In two instances clear evidence is obtained of partial liquefaction 
and incorporation of a micaceous schist by a rock of granitic com- 
position. The first of these is from a creek above the Falls of the 
Akpa Iyefe; the second a gneissic band in the very similar mica- 
schists of the river bed above Mkpot. In slides prepared from these 
rocks can be studied the partial solution of felspar, muscovite, and 
biotite by an agent which generally is felspar, but occasionally quartz. 

In the Mkpot example blunt tongues of felspar (apparently albite) 
frequently containing quarts vermiculé have forced their way through 
the edges of the original porphyritic orthoclases of the younger rock. 


1 See outline map of the Oban Hills, Q.J.G.S., vol. Ixiii, p. 314, 1907. 
2 Q.J.G.8., vol. lvi, p. 316, 1900. 


Southern Nigeria, West Coast, Africa. D381 


This is a fine-grained porphyritie biotite-gneiss. The microscopical 
character of the mica-schists of the lower reaches of the Akpa lyefe 
need be but briefly described. One of the most typical examples 
taken from about half a mile below the Falls is distinguished by the 
abundance of a reddish-brown and reddish-yellow mica. The mineral 
forms exceedingly irregular and tattered flakes, which are always 
small. Less common than this biotite, and associated with it, are 
erystals of muscovite. Quartz and an acid plagioclase build up the 
greater part of the rock. 

Other specimens contain nearly equal quantities of biotite and 
hornblende. Quartz is locally very abundant; the plagioclase may be 
of rather a basic variety; sphene and apatite are accessory minerals. 

The pegmatoid granites associated with the mica-schists of the Akpa 
Iyefe are a well-marked group. The clearly intrusive nature of these 
rocks and the closeness of their relations to the schists, the one 
succeeding to the other without sign of chilled edges and with the 
utmost irregularity, make them of some interest. Their texture 
varies considerably ; some coarse varieties, forming ill-defined veins, 
are remarkable for their large pink orthoclases and lump-like masses 
of quartz having a pegmatoid habit. Doubtless they differ slightly in 
date of intrusion. Small brownish-red garnets, plates of muscovite 
occasionally about an inch across, and, not least important, small 
nests and crystals of black tourmaline are usual accessories. Biotite 
is found occasionally, but rarely in quantity. Except some aplite 
dykes, these coarse varieties appear to be the youngest members of 
the series, and form irregular veins in a finer-grained rock of 
essentially the same composition and appearance. 

‘The mica-schists of the Kwa River in the neighbourhood of the 
Falls below Abuton are usually reddish-brown close-textured rocks, 
remarkably well foliated. The mica is by far the most conspicuous 
mineral. In other specimens the rocks are very massive, brownish- 
black in colour, and speckled with crystals of felspar. Now and 
again hornblende-schists occur sparingly. Characteristic of the 
neighbourhood is the occurrence of a tourmaline-bearing garnetiferous 
gneiss, which is associated with the schists so closely as to produce 
a beautifully banded rock by a process apparently of lt-par-lit 
injection. This banding is sometimes on a broad scale and not very 
clear, and at others finer and exceedingly regular. Now and then 
the two rocks interlock in wedge-like forms, while the intrusive 
nature of the more acid is shown by the presence of fragments of the 
schists, more or less disintegrated, contained by it. 

The Gnewsses.—Descriptions of a few sections at and between the 
villages of Netim and Ibum on the western side of the Oban Hills 
will serve to show the nature of the gneiss of the country. 

At the first stream north of Netim on the Netim-Ibum path the 
oldest rock is a biotite-hornblende-schist rich in the ferromagnesian 
minerals, and containing some quantity of a yellowish-green con- 
stituent, probably epidote. This passes into a biotite-gneiss, or, 

1 Compare G. A. J. Cole on the production of banded gneisses by the incorporation 
of sedimentary and igneous material by an invading granitic magma (‘‘ Marginal 
Phenomena of Granite Domes’’: Rep. Brit. Assoc., 1905). 


532 J. Parkinson—Foliated and non-Loliated Rocks, 


I believe, more accurately, the latter is intrusive. In places this is 
almost a granite, and is characterized by porphyritic crystals of 
orthoclase, half an inch or so in length, often retaining their 
rectangular outlines. Now and again these rocks are cut by a second 
gneiss, also containing biotite, though not in great quantity, and 
distinguished from the first by containing no phenocrysts and by 
being on the whole of finer texture. Distinct in certain localities, no 
hard and fast line probably exists in reality between the two. 
A differentiation obvious in one place had not apparently taken place 
in another. 

Associated with these rocks, and clearly later in date than they, are 
masses and veins of a coarse pegmatite (the crystals of pink orthoclase 
may be a couple of inches in length), and here and there aplite veins 
still later in date cut through the whole. 

_ To avoid misconception it should be stated that, in this locality, 
the biotite-hornblende-schist above mentioned exists only as fragments, 

and not in well-defined exposures free from acid intrusions. The 

evidence rests on lenticular bands and inclusions with torn and frayed- 
' out edges passing more or less rapidly into the surrounding gneiss. 

In such a series it is useless to expect constant lithological types, 
and the country between Netim and Ibum,,a distance of 24 miles, 
provides examples to show that every gradation exists between the 
rocks above mentioned. The principal points are born out by the 
excellent exposures of rock on the Calabar River and on an important 
tributary joining the main stream where it is crossed by the Ibum 
Path, a few miles south of that village. Near the path a biotite- 
granite is the predominant rock, but higher up the main stream 
irregular fragments of a fine micaceous gneiss or schist are contained 
in a gneiss of more acid composition. The biotite in the former rock 
forms minute flakes, and the quartz and felspar cannot be differentiated 
by the naked eye. Later than either is a coarse quartz-orthoclase- 
plagioclase rock, some of the quartz grains being nearly a quarter of 
an inch in length. This is a pegmatite. 

Examination of thin sections shows that in the micaceous gneiss or 
schist reddish-brown flakes of biotite are the only coloured constituent, 
with the exception of a few grains of an iron oxide and some small 
garnets. The felspars are represented by microcline, orthoclase, and 
an acid plagioclase, quartz is rather less abundant than the felspars, 
and exhibits crush shadows. The structure of the rock is granulitie, 
and quarts de corrosion occurs here and there. The more acid gneiss 
consists almost entirely of quartz and of felspars of the same varieties 
as in the first instance. Lobed growths of quarts vermiculé in felspar 
are common. ‘The rock differs but little from a granite. 

Passing to the tributary stream above mentioned we find the 


irregular relation of basic to acid components giving place to a regular - 


banded structure, occasionally well developed over a comparatively 
large surface of rock. Relation to the more irregular type is shown 
by the ends of a band tailing out into elongated wisps or streaks. 

The rapid loss of foliation, by which the gneisses pass into granites, 
may be studied between the Calabar River and Ibum. The former 
rock contains angular inclusions, i.e. more basic patches, obliquely 


— Southern Nigeria, West Coast, Africa. 00 


truncated by one more acid; these occur also as streaks and irregular 
bands. Comparison of a series of specimens taken from a distance of 
about four yards demonstrates a passage between granite and gneiss, 
the only differences being distinctness in foliation and banding of 
the mica; texture and bulk composition remaining the same. 

The Granites.—Under this heading are placed all the later intrusive 
masses of acid composition, distinct from those grading into gneisses. 
They vary greatly in composition; doubtless they vary greatly in age. 

One of the best-marked masses in the Oban Hills ‘s the strikingly 
porphyritic rock of Itara. It is found near the word ‘ Huts’ (in the 
map of 1903), to the north of the village of Ikuri, and extends south- 
wards along the drainage basin of the Ukpong River, almost as far as 
Ibum. The rock is a biotite-granite, rich in quartz, and containing 
a multitude of crystals of pink orthoclase, occasionally a couple of 
inches in length. In a thin section the characteristic mica is of 
a yellowish-green colour; sphene and an epidote are common, and 
small crystals of apatite are not rare. The order of consolidation was 
apatite, sphene, epidote, biotite. Locally the rock is cut by aplite 
dykes. The typical granite of Ibum, near the headwaters of the 
Ukpong River, is a fine-grained, non-porphyritic rock containing 
sufficient biotite to give it a well-marked speckled appearance. Quartz 
is plentiful, and in places a suggestion of foliation may be noticed. 

About 15 miles north of the small river called ’Ndi ’Ncha, between 
{Ibum and Netim, I found a small boss of a rather peculiar granite. 
The rock is of a medium degree of ‘coarseness, characterized by blade- 
shaped and apparently homogeneous crystals of hornblende, scattered 
without orientation through the rock. Thin sections show these to 
consist of grains of green hornblende mingled with flakes of biotite. 
In some respects this rock, which has undergone a considerable amount 
of crush, is not quite a normal granite. Thus both ferromagnesian 
minerals enclose numerous grains of quartz or are greatly indented by 
them in a semi-poecilitic manner, the crystallization dates of the two 
minerals not being very different. Lobed outgrowths of felspar 
containing quartz vermiculé are also common. Microcline is absent, 
orthoclase predominates, although albite or oligoclase is abundant. 
Apatite is exceptionally plentiful, and one slide contains some 
interesting crystals and grains of white sphene. 

The granite forming the left bank of the Calabar River, one quarter 
of a mile above Uwet (now being quarried by the Public Works 
Department), is of a grey-coloured uniform rock of medium texture, 
practically devoid of hornblende or mica. The rock is composed of 
almost equal proportions of quartz and felspar; the latter includes 
orthoclase, microcline, and an acid plagioclase. Numerous small 
flakes of muscovite and occasionally granules of impure calcite are 
developed in the felspar, the former not seldom in considerable 
quantity. 

At ’Nsibimba, on the eastern side of the hills, is a very hard and 
massive biotite-granite containing rare garnets and muscovite; quartz 
and orthoclase are both abundant, and together build up practically 
the whole of the rock, for a triclinic felspar is exceedingly scarce. 
The rock has been only slightly modified by pressure. 


584 R. H. Chandler—Drift at Bostall Common. 


The granite of Uwet differs considerably from the granites found 
between the Calabar River and the Lyangita in the neighbourhood of 
Uyanga and Ojo ’Nkorimba. The latter recalls the porphyritic 
granite of Itara in containing sphene as an important accessory 
constituent, and, in the presence of a mineral resembling epidote, 
certainly of primary origin, the identification being at present doubtful. 

The rock from the lyangita towards Iwudu contains some quantity 
of a strongly pleochroic green hornblende, and traces of the same 
mineral appear in the granite north of Ojo ’Nkorimba. Well-built 
crystals of brown biotite are conspicuous in all slides examined from 
this part of the district. Orthoclase is the predominant felspar; but 
the rock a short distance south of Uyanga contains large crystals of 
microcline, as does also a specimen collected between the Lyangita and 
Calabar Rivers. The plagioclases, commonly zoned, appear to be 
albite or oligoclase, or both. Large grains of quartz are plentiful, 
and quarts vermiculé is common and characteristic. In some specimens 
tourmaline occurs, but it is very rare. One or two of the rocks haye 
been very slightly crushed. 

The red aplites, which are apparently the latest igneous rocks of 
the lower Akpa Iyefe (for basalt dykes are not seen), consist of an 
ageregate of felspar and quartz, the former mineral slightly pre- 
ponderating over the latter. Micropegmatite, the possible presence of 
which is suggested by the hand-specimen, is found to be but feebly 
represented; a thin, not very well defined rim of intergrowth is, 
however, usual where quartz and felspar meet. A point of some 
interest lies in the composite nature of the felspars; due, either to 
an almost complete resorption of an early generation of the mineral, 
or to a later influx of felspathic material which has partially dissolved 
the pre-existing mineral and embedded the fragments within its own 
substance. 

Aplites also cut the porphyritic granite of Itara (along the valley 
of the Ukpong River). The same rocks, intrusive in hornblende- 
schists, are conspicuous in a creek running into the Agboyip River, 
itself a tributary of the Ukpong; and to the north of the village of 
Awi (south of Nsan), ete. 

In distinguishing between the granitic gneisses and the later 
granites mention may be made of the fact that, as a systematic 
investigation of the alluvial deposits proves, monazite is characteristic 
of the former. 


II.—On a Drirr at Bostatt Common, NEAR PLUMSTEAD. 
By R. H. Cuanptzr. 


APPING a small patch of London Clay on the highest part of 
Bostall Common (284 O.D.'), there is a ‘drift’ that presents 
peculiarities identical with part of the gravel on Shooters Hill 
(2 miles distant) at 424 O.D.* 
The gravel at Shooters Hill has been frequently described, so 


1 Both these heights are the highest points of the drift. 


R. H. Chandler—Drift at Bostall Common. 5980 


need not be detailed here. It consists of a coarse, clayey gravel of 
rounded flint pebbles and beds of sand. Some of the pebbles are 
very much corroded outside, split into several pieces, and present 
curious coloured zonings.! Lower Greensand chert and quartz 
pebbles are rare, and quartzite pebbles very rare. A very characteristic 
feature is the presence of the above-mentioned corroded, split, and 
zoned pebbles. The rough cortex of the pebbles show knobs and 
pits as though partly decomposed by an acid, and for which no 
other word than ‘corroded’ seems applicable. The splitting may 
be along any axis, but is frequently parallel to the long one, and is 
not the usual frost shattering or pitting; a pebble may be found 
in three or four pieces and the pieces close together, as though 
the fracture were of recent origin. The zoning is also curious, and 
some pebbles show (on the split surfaces) several differently coloured 
concentric bands, evidently due to weathering and staining. An 
interesting point about these corroded and zoned pebbles is that 
the inner zone is frequently of an opaque cream colour, and is 
surrounded by brown, black, red, or other coloured translucent flint, 
and then comes the cream opaque cortex; whereas in ordinary 
weathered flint pebbles the translucent part is in the centre. These 
three points (i.e. corroding, splitting, and peculiar zoning) at once 
claim attention, and serve to give a characteristic feature to the 
eravel, and to distinguish it from the other ‘Hill’, or ‘ Terrace’ 
gravels of the surrounding district. 


Shoolers Hull 


Bostall 


¥ Cravel, 


Section from Shooters Hill to Bostall Common showing the relation of the 
‘drifts’ and the erosion by the East Wickham stream. Horizontal scale 1inch = 
1 mile, vertical } inch = 100 feet. 


The Shooters Hill gravel rests on about 180 feet of London Clay 
and, as a recent section showed, Bagshot Sand in places.” The 
drift at Bostall Common caps the highest part of the Common, which 
consists of a circular patch of London Clay, about 100 yards in 
diameter and about 10 feet thick, and is separated from Shooters 
Hill by 13 miles of Blackheath, and Woolwich and Reading Beds 
(see Section). The gravel occurs as a thin sprinkling on the surface 


1 Mentioned by Dr. A. E. Salter from notes by Mr. A. L. Leach, Woolwich 
Surveys, 8vo, p. 19, Woolwich, 1909. 
2 A. L. Leach, Gout. Mac., Dec. V, Vol. VII, pp. 405-7. 


536 Rk. H. Chandler—Drift at Bostall Common. 


of this small patch of London Clay, and agrees very closely in com- 
position with the Shooters Hill gravel at a level of about 200 feet 
higher. 

The extent of the spread of drift was revealed during the last 
two winters, when the top of the hill on Bostall Common was 
removed by the London County Council unemployed, and all the 
moderately large stones hand-picked and placed on one side. By 
looking over these heaps it was possible to form an accurate opinion 
of the composition of the drift, and it was then that the similarity 
to Shooters Hill gravel became so apparent. I have had the corroded, 
split, and zoned pebbles here in abundance, also two quartzite pebbles 
(this quartzite is curiously marked — precisely like one obtained 
from Shooters Hill), and a piece of the Lower Greensand Chert. 
Quartz pebbles I have not found, but as they would probably be 
small (as at Shooters Hill) they would not stand such a chance 
of being picked as the larger pebbles; this may account for their 
apparent absence. 

The height of 234 O.D. is above any of the terraces associated 
with the Thames in this neighbourhood; moreover, the gravel is 
different from the Terrace gravels in that it contains no (or very 
few) subangular flints, no Bunter quartzite, Rhanella chert, or 
igneous rocks, all of which are plentiful in the terraces. 

Mr. F. C. J. Spurrell has suggested! that this drift might be 
the remains of a Boulder Clay, or of its subjacent gravel, but con- 
sidering its curious composition I suggest that it is more likely to 
have been derived as a ‘trail’ from the gravel on Shooters Hill, at 
a time when that mass of London Clay and its capping of gravel 
was much more extensive than at present. A reference to the sketch 
will show that this source of supply has been cut off for a long 
time ; for the East Wickham stream, which rises on the slopes of 
Shooters Hill (as soakage from the gravel), and finds its way to 
the Thames at Plumstead, has now separated the patch of London 
Clay at Bostall Common from the mass of Shooters Hill by a valley 
150 feet deep (in the line of section), and there has been uncovered 
an outcrop of the Lower London Tertiaries 13 miles wide. 

An alternative hypothesis is that the Bostall Common drift was 
once continuous with Shooters Hill gravel and at about the same 
level, and that it has been separated from Shooters Hill by the 
cutting back of the East Wickham stream, whilst denudation has 
lowered Bostall Common vertically from about 404 feet O.D. (the 
height of Shooters Hill less the gravel cap) to 284 feet O.D., by 
reducing the London Clay from 180 feet to 10 feet; possibly because 
its original capping of gravel was not so thick, and hence unable 
to act so protectively.’ 

The suggested hypothesis seems more workable (i.e. a trail from 
Shooters Hill down the slope of London Clay), and this feature 


1 “A Sketch of the History of the Rivers and Denudation of West Kent, etc.”’ : 
ene W. Kent Nat. Hist. Soc., 1886, p. 19. ‘This appears to be the first and only 
reference. 


* There is a remarkable agreement between these figures. 


L. Richardson—Great Oolite, Oxfordshire. 587 


may be seen at the present day at Swanscombe, in the tramway 
cuttings of the Associated Portland Cement Company, where foundered 
London Clay and its capping of gravel (different from that on 
Shooters Hill) trail down from Swanscombe Hill (300 feet O.D.) 
to about the 100 feet contour-line; the chief difference between the 
case of Bostall Common and that of Swanscombe being that at the 
latter locality the source of supply has not been cut off by a later 
stream, and that at the former the London Clay appears to be in 
situ and the drift only to have trailed. 


I1t.—Tue Grear Ooritre Secrron at Groves’ Quarry, MILTon-UNDER- 
Wycuwoop, OxForRDSHIRE. 


By L. Ricwarpson, F.R.S.E., F.G.S. 


N the occasion of a recent visit to the quarry in the Great Oolite 

at Milton-under-Wychwood, which has become known amongst 

geologists as ‘‘Groves’ Quarry, Milton”, Mr. EK. T. Paris, F.C.S., 

and I were disappointed to find that no quarrying operations were in 
progress and that apparently they had ceased for good. 

Messrs. Groves Brothers worked the quarry from 1846 onwards for 
about fifty years; but then it was acquired by a firm who afterwards 
traded as ‘‘The Taynton and Guiting Quarries, Limited”. The 
Great Oolite limestone that was worked here obtained considerable 
repute in building circles and was of two kinds. One was derived 
from the whitish beds that weather into great block-lke masses; and 
the other, from the yellower beds at the base. In the trade, both 
kinds were known as ‘ Taynton Stone’; but the first was described as 
‘No. 1’, and said to be ‘‘a fine-grained, cream-coloured oolite”’; 
while the second was denominated ‘No. 2’ and was stated to be 
a “similar stone, but a shade warmer’’. 

As the faces of the workings are in danger of becoming partially 
hidden, and the lower beds certainly will become more and more 
obscured as additional talus accumulates, and as the last working to 
be abandoned affords the most continuous view of the component beds 
of the Great Oolite that there is for many miles round, it appeared 
desirable to record and publish a detailed account. In obtaining 
these details I have had the valued assistance of Mr. E. T. Paris, who 
has named the echinoids mentioned in the section below. 

The precise position of the quarry, for which it will be probably 
best to retain the name of ‘‘ Groves’ Quarry’’, is two miles south-west 
of Shipton-under- Wychwood Church. There is a station at Shipton 
on the Great Western Railway line between Kingham and Oxford. 

Although, following precedent, I have therefore called the quarry 
‘Groves’ Quarry’’, there are actually four workings at the four 
corners of a somewhat quadrate area, the central portion of which is 
oceupied with vast spoil-heaps. 

The south-western working was the last to be abandoned, and it 
was in this that the details noted below were mostly obtained. 


FOG L. Richardson—Great Oolite, Oxfordshire. 


Upper Srace. 


crinoid-ossicles. 


GREAT-OoLITE SEQUENCE AT Groves’ Quarry, Mitton, OxForRDSHIRE. 


Thickness in 


Limestone and some marl, white, rubbly. This rubble (and 
that of the bed below when it comes near the surface) assumes 
a yellow colour, and one or the other or both (i.e. 1 and 2) 
constitute the cap to the section : about : 
Limestone, white and pale-brown, finely oolitic ; Anabacia 
complanata (Defr.), not uncommon; Montlivaltia caryo- 
phyllata, Lamx., Montlivaitia sp., Thamnastrea lyelli, 
E. & H., Ch ypeus milleri, Wright, Echinobrissus woodwardi, 
Wright, Volsella imbricata (Sow. ) ‘and Ti igonia costata, Sow. 
3 Marl, pale- brown, rather sandy, with brown and black pieces of 
lignite and occasional limestone pebbles 
a. Marl, greyish-white (clayey and darker at the top); indurated 
in places; Lucina bellona, d’Orb., and Unicardium varicosum 
(Sow.) : 
d. eae white, rubbly, non- -oolitic and impersistent : in 
places yellow-stained. When weathered forms a conspicuous 
yellow wavy band at the base of Bed 4a; Strophodus magnus, 
Agassiz, Lhamnastr ea lyelli, KH. & Tei ?Isastrea limitata 
(Lamx.), 2 Trochotoma, Natica, Ter ebratula maxillata auctt., 
Camptrnectae rigidus (Sow.), Grammatodon hirsonensis 
(VArch.), Ostrea sowerbyi, M. & L., Lima cardiiformis 
(Sow.) y olsella imbricata (Sow.): 4 to 8 inches . 
Man of Z greenish tinge weathering white ; apparently unfossili- 

if ferous. The white colour of this bed, the yellow band (48), 

it and the top darker marls (4a) are very conspicuous in 

a weathered face: about 
( TEREBRATULA - BeDs. — a. Limestone, white, sparsely- oolitic, 
crowded with Zerebratula maxillata auctt., in places; Clypeus 
mulleri, Wright, Hemicidaris bravenderi, Wright (and large 
| detached radioles probably belonging to this species), Acro- 
salenia spinosa, Agassiz, Echinobrissus woodwardi, Wright, 

Eryma elegans, Oppel, Natica, Nerinea, Rhynchonella sp., 

Serpula tricarinata, Sow., Camptonectes lens (Sow.), C. annu- 

latus (Sow.), Ceromya concentrica (Sow.), @. Symondsi, 

M. & L., C. undulata, M. & 1u., Gervillia cf. waltoni, Lycett, 

Grammatodon hirsonensis (d’Arch.), Lueina bellona, @Orb., 

64 Ostrea costata, Sow., Lima cardiiformis (Sow.), Protocardia 

subtrigona (M.& L.), Zhracia curtansata, M. & L., and 
' Volsella imbricata (Sow.)  . : : 

b. Marl, greenish, with a yellow layer at the base. In places 
the bed above is joined on to the bed below, and when such is 
the case the top portion of that bed (6c) becomes very fossili- 
ferous, containing many of the fossils of the bed above (6a) ; 
otherwise it is rather barren: 1 to 3 inches . 

. Frrst Brock Brep.—Limestone, white, sparsely but coarsely- 
oolitic, massive, weathering into blocks ; Clypeus mulleri, 
Wright (common), Rhynchonella sp. (same form as in 6a) 

( Marl, ereenish - -grey in the upper two-thirds, becoming browner 

i 


5 


a 


is) 


in the lower third, with a general tendency to weather white ; 
apparently rather barren of fossils 


fis ete 
Be yh 
3° 10 
ORS 
2 To 
(ie 
LO 
Leer! 
Ope, 
TG 


1 From beds 4, 5, or 6 come some peculiar little objects that somewhat resemble 


Mr. W. D. Lang informs me, however, that they are concretions, 


‘¢and similar ones are common in the chalk. Stripes on the sides are said to be 
slickenside structure, and the whole comparable with cone in cone structure.”’ 
In this paper, when a query precedes the generic name, it indicates doubt about 
the genus haying been accurately diagnosed. 


Urrrr Sricn. 


L. Richardson—Great Oolite, Oxfordshire. 


539 


Thickness in 


a. Limestone, white, sparsely-oolitic, comparatively barren, and 
forming a cap to the limestone below (8c); Nerinea sp., 
Terebratula maxillata auctt. : about , ; ; 

§ < 6. Marl, greenish, often wanting: 0 to 4 inches 

ce. Szeconp Brock Bep. —Limestone, massive, weathering into 
blocks, whitish, crystalline-hearted, not usually very fossili- 
ferous ; Gervillia cf. waltoni, Lycett, Terebratu/a sp. 

Marl, brown, clayey, with a ereenish- grey zone at the centre and 

9 - rubbly limestone in the lower portion ; radioles of Hemieidaris 

bravenderi, Wright (common), Ostrea sowerbyi, M. & L., and 

Serpula : about : ¢ 


nea. 


Tuirp Brock Ben. — Limestone, not so prominent, dirty 
pan -grey and brown, with white shell- fragments 
. Marl, brown, with comminuted shells passing down into brown 
ana grey- blotched, sandy, clayey marl, with occasional thin 
eae layers towards the base 
a band, dark, the black colour being due to plant- -remains 
- Marl, ereenish- -grey, sandy, with plant-remains common. 
ais the south-eastern working this is the olay that anne 
oe ) Passes down into 
. Limestone, greenish-grey, sandy, with an even upper surface ; ; 
a iyexticall plant-remains, the cavities where they have been 
weathering so as to resemble borings 
6. FourtH Brock Bro. —Limestone, ‘hard, masslv ive, ereenish- orey, 
weathering white and into large blocks, but inter nally extremely 
hard and somewhat resembling Carboniferous Limestone 

Clay, pale greenish-grey, sandy, marly : : . 5 

- Limestone, yellowish-brown and greenish, sandy, with well- 
spaced yellow oolite-granules. Sometimes a regular bed, but 
difficult to measure, a disappearing in the south- 
eastern working . 


} 
\ 
i Marl, brownish- ereen, often indurated to form an impure 


10 


iil 


13 


J 14 


rubbly oolitice limestone, with eee white oolite- 
granules, passing down into 
A conspicuous blue shaly clay! ; Placunopsis. socialis, M. & ee 
Ostrea sowerbyi, M. & Li., Rhynchonella sp.: 4 to 10 inches . 
. Clay, browvish-green, marly, with Geeaticual irregular seams 
of brown oolitie marl or limestone, with the same species of 
poe as in 158; and this mto ‘ 
. Upper Osrrea - Bep. — Marl, brown, clayey, indurated, 
Cee. crowded with Ostrea sowerbyi, M.&L. . 

The last layer (15d) is intimately associated with the top 
eee of the bed below, which is :-— 
. Limestone, rubbly, oolitic, passing down into more compact, 
fitiacéy, coarsely- oolitic limestone, the weathered surfaces of the 
slabs of which exhibit innumerable small Gastropods, etc. 
eat YGurus sp. 
_ Thin courses of oolitie limestone and shaly marl, ‘softer than 
as overlying limestone, with a hard band of very "oolitie lime- 
stone at the base. This bottom band has large white oolite- 
granules, and is very shelly; Jsocrinws-ossicles, echinoid- 
_adioles, Pseudomonotis echinata (Sow.) : ‘ 
. Pale-yellow oolitic marl and rubble: 1 ft. 6 in. to 
. Lower Osrrea-Brep.—Deposit of pale-yellow and yellowish 
"marl, enclosing an extraordinary number of oysters and Riyn- 
chonelle. Most of the oysters have Serpule, polyzoans, and 
occasional specimens of Webbina on them, and are frequently 
pierced by the boring sponge Zadpina, thus showing that the 
deposit in which they oceur was of slow formation . 


Ss 


age 


Se. 


bo 


or 


la So) 


ine} 


bo 


2 


wm, 


i) (=) 


oom 


8 


1 Absent as such from the south-eastern working, where bed lée is thicker, 


tolerably conspicuous, and more of a limestone. 


540 L. Richardson— Great Oolite, Oxfordshire. 


Thickness in 
in. 


a. Limestone, well-oolitic, with coarser oolite-granules and shell- 

a debris ; often obliquely stratified. Splits up at the top, and 
g 18 greenish shaly marl is intercalated; Ostrea sowerbyi,M.&L. 2 6 
D 6. Green and brown shale in alternating layers ; lignite OnE 
2 a. Limestone, in three beds, oolitic and shelly in places; Ostrea 2 0 
les b. Rubble and marl with Ostrea (common); radioles: lto4in. 0 2 

© \ 94 ¢. Limestone, massive, shelly, oolitic. Top somewhat waterworn 

4 and in uppermost 2 inches Chlamys vagans (Sow.) is not 
uncommon: seen : ° ‘ - : ; : >») OameO 
50/730 


South-Western Working.—This working, as already mentioned, was 
where the stone was last worked, and where the succession of beds 
from sixteen upwards was noted. The blocks that are lying about, 
and are so full of specimens of Zerebratule, will be readily-recognized 
as having come from bed 6. 

It will be unnecessary to say anything more about this working, as 
the record given above is so full. 

South-Eastern Working.—In the eastern face of this working, which 
is the more weathered of the two, and therefore that in which the 
hard bands stand out in greatest relief, the principal beds that can be 
readily found are the disturbed top-limestones (beds 1 and 2); the 
rather greenish’ marl (4a) with a yellow band (44) at the base; the 
white marl (5); and then the four great block beds (6c, 8c, 10, 126), 
of which the upper two are the most massive. The third and fourth 
block-beds down, when traced along the southern face of the working, 
become relatively inconspicuous. In the eastern face, below the fourth 
block-bed, come marls (18 and 15a) with a median, rather impersistent 
limestone (14), and then rubbly limestone (15c) at the very base. 
This rubbly limestone, when followed along the southern face, is seen 
immediately above the Upper Ostrea-Bed, which—with the Lower 
Ostrea-Bed—will form a quick means of locating the minor divisions 
that have been made in the lower portion of the section. It should 
be particularly noticed that the blue marl (154) is absent as such from 
this working. 

It is in this working that the Lower Ostrea-Bed is best developed 
and most conveniently investigated. 

North-Eastern Working.—In this working—now long abandoned— 
the highest beds seen are those in the eastern face. The two lime- 
stones are the two top block-beds, and the second one is the top-limestone 
of the western face. Here, the third block-bed is poorly-developed ; 
but the fourth is more conspicuous and has underneath it greenish 
marl—bed 13. The Upper Ustrea-Bed can be located above bed 16a, 
which is the limestone protruding at the bottom of the working. 

Western Working.—Vhis working runs below and parallel to the 
road. The top conspicuous limestone is the lowest block-bed (126), 
and the green marl immediately below it is as conspicuous as ever. 
The Upper Ostrea-Bed is the next easily-found horizon. Below it is 
the limestone (16a) and the softer marls, which form the lower portion 


1 Looks greenish, but upon closer inspection is better described as ‘ greyish- 
white ’. 


L. Richardson—Great- Oolite, Oxfordshire. 541 


(2) of bed 16; but both divisions (that is, ¢ and 4) are much thinner 
here. Below, again, is the greenish marl that occurs on top of the 
Lower Ostrea-Bed ; while at the base of all is seen the top portion of 
the yellower freestone-beds, which are seen to a greater depth in 
a small opening to the north, nearer the cottages. 

Previous Literature.—Professor E. Hull was the first to publish any 
remarks upon the Milton section. He wrote—! 

‘On Milton field, in a large quarry, a section similar to that at Windrush is 
exhibited. There we find about 17 feet of interstratified marls, shales, and thin- 
bedded limestones, highly fossiliferous, resting on thick- bedded oolite more than 
12 feet thick, and yielding large blocks, the one belonging to the upper zone, the 
other to the lower.” 

The ‘‘ thick-bedded oolite”’ is numbered 18 and 19 in my section. 

The late R. F. Tomes visited Milton with a view to seeing if there 
were any corals there.» He found one bed (number 4 of his record) 
sufficiently rich in them to cause him to name it the ‘ Coral-Bed’ ; 
but apparently he obtained nothing worth keeping or identifiable 
therefrom, because all the corals he lists came from a bed lower down 
—his bed 6. Mr. Paris and I found corals in beds 2, 46, and 6 of the 
record given above. Tomes also gives a record of the beds exposed 
at the time of this visit to show the positions of the coralliferous 
limestones; but whilst it is obvious that his beds 17 and 19, or at 
least the portions of them that contain oysters in abundance, correspond 
to my beds 15 and 17 respectively, it is not so easy to say more than 
that his bed 6, that is, ‘‘stone in large blocks,” appears to be my 
bed 6c. 

Mr. H. B. Woodward, the next author to notice this section, also 
appears to have encountered some difficulty in making out Tomes’s 
section, for he came to the conclusion that the topmost five beds of 
Tomes’s record ‘‘ were not clearly exhibited at the time he visited the 
quarry”. He therefore repeated Tomes’s observations so far as those 
beds were concerned. After that he found it necessary to make his 
own section, which differs materially from Tomes’s. 

When Mr. Paris and I visited Milton there were no quarrymen 
about so we were unable to check our identification of the ‘small 
land-stones’ with bed 6a of the present record; of the ‘Blue Rag’ 
with bed 124; and of the ‘ Bastard White Rags’ with bed 14. But 
I think the identifications are correct, and this being so there is 
a noticeable correspondence between my record and Mr. Woodward’s 
down to bed 15d, which is his ‘‘ brown clay with Ostrea sowerbyi and 
Rhynchonella concinna (abundant)’’. But then there is a difference. 
Bed 15d is my Upper Ostrea-Bed, and it occurs at 7 ft. 4 in. above 
the Lower Ostrea-Bed. Above the Upper Ostrea-Bed is a conspicuous 
blue shaly clay (15d). Mr. Woodward notes above his ‘‘ brown 
clay with Ostrea sowerbyi, etc.”, ‘blue clay.’ So I think that 
Mr. Woodward’s Oyster-Bed is really the Upper Ostrea-Bed, and that 
in going from one working to the other to complete the downward 
succession he may have overlooked the fact—as could easily be done— 


1 Mem. Geol. Sury.: ‘‘ The Geology of the Country around Cheltenham,” 1857, 
p. 58. 
2 Quart. Journ. Geol. Soc., vol. xli, p. 171, 1885. 


542 A. R. Horwood—Post- Pleistocene of Central England. 


that there were two such beds, and therefore identified the Upper 
Ostrea-Bed of one working with the Lower of the other. 

As regards the Freestone-Beds, there is general agreement between 
the present record and that given by Mr. Woodward. 

In 1906 the Cotteswold Naturalists’ Field Club saw Groves’ Quarry, 
and it was remarked that the beds were less massive than those of 
the Great Oolite that were quarried in the neighbourhood of Bath.? 

It is not purposed attempting any detailed correlations of the beds 
in this section with those elsewhere. The time is not ripe; but it 
may be as well to draw particular attention to the following points :— 

(1) The somewhat abundant occurrence of specimens of Anabacia 
complanata (Defrance) in bed 2, and the presence of the echinoids, 
Echinobrissus woodwardi, Wr., and Clypeus milleri, Wr. 

(2) The very fossiliferous nature of bed 6, all the fossils being 
noteworthy for correlation-purposes. 

(3) The relative barrenness of the marl-beds associated with the 
fossiliferous top-limestones. 

(4) The distinctive lithic structure of bed 14 and its richness in 
specimens of Cypricardia spp. and Volsella imbricata (Sow.), and to 
a less extent in certain other Lamellibranchs. 

(5) The not infrequent occurrence of Placunopsis socialis, M. & L., 
in bed 15d. 

(6) The occurrence of two conspicuous Ostrea-Beds (15d and 17), 
7ft. 4in. apart. The oysters in the lower bed are usually encrusted 
with Serpula tricarinata, Sow., Berenicea spp., occasionally with 
Webbina, and are frequently pierced by the boring sponge Zadpina. 


IV.—Tue Postr-Puietsrocenr Frora anp Fauna or CenrraL ENGLAND. 


By A. R. Horwoop, 
Leicester Museum. 


ee central position of Leicestershire gives it not only a peculiar 

relationship in regard to river-drainage, streams radiating from 
its plateau-frontier on the one hand to the north, flowing into the 
Humber, and on the other to the south into the Bristol Channel, 
separated alone by a now comparatively insignificant divide in the 
neighbourhood of Lutterworth. Also the very fact that this divide 
is given, by the otherwise lowland character of the tract to the 
north and south, a barrier-like aspect, renders it highly probable that 
the flora and fauna in this basin-like area is more or less homogeneous. 
That it has been uniform in character, no doubt from pre-Glacial 
times, when doubtless the existing drainage systems (though probably 
still more ancient fundamentally) received their most recent stamp, 
having been little modified (except in depth or width) during Glacial 
or later times. For this purpose we must needs summarize all that 
is known as to the occurrence of plants or land and freshwater Mollusca 
in post-Pleistocene alluvial deposits. 

\ The Jurassie Rocks of Britain—The Lower Oolitic Rocks of England (Yorkshire 
excepted), vol. iv (1894), p. 307. 

* Proc. Cotteswold Nat. F.C., vol. xvi, pt.i, p. 32, 1907; see also Geology in the 
Field (Jubilee vol. of the Geol. Assoc.), pt. 2, p. 356, January, 1910. 


A. R. Horwood— Post-Pleistocene of Central England. 548 


Soar VALLEY. 


In the county of Leicester itself no adequate account of any 
post-Pleistocene remains other than mammalia’ has been published. 
The first notice is the result of a natural history competition which 
was carried on for some years before the present Museum had assumed 
any important position. Mr. F. IT’. Mott? reported the discovery of 
shells of the genera Limnea, Succinea, etc., in gravel at Belgrave,’ 
stained with iron-oxide. This gravel is doubtless part of the alluvial 
sand and gravel which covers the lower part of the Soar Valley. 
This locality is north of the town. Somewhat to the south another 
locality, Aylestone (excavations for gasworks),* has afforded more 
abundant evidence of a flora and fauna similar to the existing one. 
Here in the Soar Valley the following section was exposed :— 


ft. ine 
1. Materials of a cart road ‘ : : 2 0 6 
2. Rough gravel (perhaps foundation of a road) LO 
3. Fine grey clay : : . z . ma) 
4, Black peat : : 1 6 
5. Soft white calcareous marl 2 0 
6. Red marl in situ. 

HOMO 


The lowest bed (5) was said to consist largely of Chara, and 
amongst the calcareous remains of the plant and seeds were numbers 
of fresh-water shells, Zimnea, Planorbis, Pisidium, Cypris, and other 
animal remains. 

The following is a list of the specimens found which passed into the 
hands of the late Mr. J. Plant, who gave them to the Museum :— 


PLANT”. Succmea putris. 
Chara vulgaris. Ancylus fluviatilis. 
cf. Potamogeton zosterefolius. Limnea peregra. 

L. peregra, var. ovata. 
= H . 

ANNELIDA. I. auricularia. 
Tubes. L. truncatula. 

(Sree Bythinia leachit. 

ey ; ¢ Planorbis nautileus. 
ef. Candona candida. P. fontanus. 

GASTEROPODA. a spirorbis. 

Ses j . parvus. 

Hyalinia cellaria. Ee 
a ira P. umbilicatus. 

Ene: Valvata piscinalis 
Felix pulchella. ; 
H. hispida. LAMELLIBRANCHIATA. 
Cochlicopa lubrica. Spherium corneum. 
Pupa muscorum. Pisidium amniewn. 


A single worn fragment of Ostrea edulis was amongst these 
otherwise lacustrine forms. The section was first noticed by the late 
Mr. W. J. Harrison, F.G.S., a former Curator. The deposits are 


1 A list of these up to 1889 was given in The Vertebrate Animals of Leicestershire 
and Rutland. It was summarized recently in the ‘‘ Victoria County History” by 
Mr. R. Lydekker. Many additions must, however, be made to both. 

2 Report Leic. Lit. and Phil. Soc., 1875, p. 42. 

3 Mr. J. Plant found Rhinoceros teeth with Succinea, Limnea, etc., in the 
Abbey Park Road, a little north of the south end. 

4 Tbid., 1878, pp. 26-8. 


544 A. R. Horwood—Post- Pleistocene of Central England. 


distinctly alluvial. The site was about 100 feet at most from the 
River Soar. At a depth of 11 feet and below Boulder-clay resting on 
Red Marl an antler of Rangifer tarandus was found close to the 
same spot. In the river gravels and alluvium at various points in the 
Soar Valley the following mammalia have been found, at the Abbey 
Meadow, Belgrave, Humberstone, Thurmaston, Aylestone, Barrow-on- 
Soar, Loughborough, Kegworth, Syston, Thurnby, Melton Mowbray, 
and elsewhere :— 


Bison bonasus, var. priscus. Elephas primigenius. 
Bos taurus, var. primigenius. Rangifer tarandus. 
Cervus elaphus. Rhinoceros leptorhinus. 
Hlephas antiquus. 


Whilst the foregoing may be Glacial, the following are of more 
recent date :— 


Bos taurus, var. longifrons. Cervus elaphus. 
Capra or Ovis sp. Equus caballus. 
Capreolus caprea. Sus scrofa. 


Cervus dama. 


As to molluscan remains in Glacial beds themselves Messrs. 
G. W. Lamplugh and C. Fox-Strangways are said to have found 
Tellina bulthica at Beasley’s Sandpit, Aylestone, in the Quartzose 
Sand, but M. Browne’ threw discredit on the discovery. We must 
say that there is no reason to doubt their occurrence, and we have 
found shell fragments there and elsewhere, though too fragmentary— 
as most Glacial contemporaneous fossils are—to determine. 


Lower Trent VALLEY. 


Passing to the north-west corner of Leicestershire and the Trent 
Valley, we find evidence of a similar flora and fauna in the Burton-on- 
Trent district. Here at Stapenhill alluvial deposits occur 17 feet 
above the Trent, and Mr. W. Molyneux, F.G.8.,*? gave the following 
section :— 


ft. in 
1. Red clay . : 4 0 
2. Stiff yellow clay . 0 6 
3. Black and yellow clay, gradually passing into ; 
a strong unctuous clay . pre) 
4, Peat containing shells and thickly charged with 
small erystals of sulphate of lime . 5 Wasi 
5. Strong yellowish-brown clay, the BDRe? pant 
thickly charged with shells : 4 0 
6. Band of coarse gravel : 0 3 
7. Hard consolidated, stratified ‘sand, with few 
pebbles 2 0 


8. Loose current-bedded white and yellow” sand, 
intersected by thin bands of peat, clay, and 
pebbles, and frequently containing lumps of 
coal and black shale . 10 0 
9. Coarse white and yellow clayey g gravel containing 
bones of animals . . : : 


1 Trans. Leic. Lit. and Phil. Soc., 1901, p. 30. 
2 Burton-on-Trent, its History, its Waters, and its Breweries, 1869, p. 182. 


A. R. Horwood—Post-Pleistocene of Central England. 545 


R. Garner, author of the Natural History of Staffordshire, identified 
in bed 5 the following shells :— 


Helix pulchella. Vertigo sp. 

HH. rotundata. Succinea oblonga. 
HH. fuiva. Planorbis sp. 
Buliminus obscurus. Limnea peregra. 
B. sp. L. truncatula. 


Vertigo substriata. 


In addition to these a diatom, Mragillaria, was detected, and the 
wing of an insect, the elytron of a beetle, etc., but not in the peat 
with the shells. In a field south of this section another was seen— 


1. Brown clay. 5 : : : 6 inches to 2 feet. 
2. Dark earthy sand : : : : 1 foot. 
3. Coarse ochreous gravel 6 1 to 2 feet. 


4. Current-bedded sand with veins of clay . 4 to 6 feet. 


6ft. 6in. to 11 feet. 


In bed 4 roots of aquatic plants, probably Jris, were found, passing 
up through the gravel above, becoming ochreous in colour. The claw 
of acray-fish, Astacus fluviatilis, was found in the gravel. At Stretton, 
on the opposite or north side of the river, the section is— 


ft. in, 
1. Strong red clay and gravel : : 5 : 10 0 
2. Yellow gravel and sandy clay . 5 ; : 4) © 
3. Yellow sand and gravel. il © 
4. Blue clay and gravel passing into strong clay, 


the upper surface containing a band of from 


2 to 3 inches of black peaty matter 2 0 

5. Coarse yellow gravel @ 9 
6. White and yellow sand and clayey gravel, with 

subangular flints 3 0 

7. Strong red marly clay and ‘gravel 2 0 

8. Tenacious dark-blue clay . Zine 

9. Deep yellow ochreous sand 0 3 

10. Strong white clayey gravel, bottom not seen 4 0 

11. Blue and brown clays => = 

30 3 


In No. 4 fragments of wood and plants have been found and 
aquatic plants in No. 8. In No. 4 very large blue and yellow flints 
derived from the Drift occur. 

In the river-gravels at Andersley, at 3-5 feet deep, roots and 
branches of trees occur, and at a lower level also, in addition, hazel- 
nuts, aquatic shells, and bones of mammalia. Professor Boyd 
Dawkins identified the latter as bones, jaws, and teeth of Sus scrofa, 
Bos longifrons, and domestic varieties, Hguus, and bones of wolf or 
dog, while similar remains have been found at Burton itself, near 
Whitehead’s Brewery, Mosley Street old river-course, sewer excavations 
at Anderstaff Lane, and at Stretton. At the Hay, below 3 ft. 6 in. of 
sand and gravel, in stiff blue and yellow clay, roots and branches of 
trees and other plants were found, and below the latter peat 
(lft. 9in.). At Mosley Street, below 5 feet of clay, 8 feet of 
peat was met with. 

DECADE V.—VOL. VII.—NO. XII. 35 


546 A. R. Horwood— Post- Pleistocene of Central England. 


Below this last horizon, in black consolidated gravel (8 feet thick), 
Edwin Brown found— 


CRUSTACEA. Planorbis contortus. 

Daphnia. Physa fontinalis. 
Limnea peregra. 

GASTEROPODA. L. palustris. 
Vertigo. L. stagnalis. 
Cochhcopa lubrica. Bythinia tentaculata. 
Suceinea putris. 
AP arate We. LAMELLIBRANCHIATA. 
P. spirorbis. Spherium corneum. 


Most of these too were found at Hay, Mosley Street, and in 
excavations for sewage tanks at Stretton. Compared with those 
found in the peats and clays at Stapenhill on the other side there is 
a difference in species. At Barton Station, south of Burton, roots of 
plants and branches of trees were met with, and containing an 
admixture occasionally of peat, 2 feet in thickness, below 6 ft. 2 in. 
of clay, sand, and gravel.1 The latter were impregnated with 
carbonate of iron and manganese, containing much vegetable matter. 
In forming No. 3 tank at Stretton the following section was 
uncovered :— 


1. Yellow clay ‘ : : : 1 foot. 
2. Blue clay, containing plants : : 6 inches. 
3. Peat . ¢ : : . ' ¢ 3 feet. 
4, Shell marl, with bones, jaw, teeth (Bos 

longifrons) . : : 6 : 1 to 8 feet. 
5. Gravel with flints, bottom not seen : 3 feet. 


Sift. 6in. to 15ft. 6in. 


The deposits were very variable, the shell marl full of shells, 
irregular, sometimes lying on gravel, sometimes on peat, or dark clay 
with aquatic shells. Plant roots penetrate from the peat through the 
shell marl into the gravel. In the blue clay matted masses of aquatic 
plants occur coated with phosphate of iron. Dr. H. T. Brown, F.R.S.,” 
gives the following section at the Sewage Works near Stretton 
(140 O.D.) :— 


Soil, subsoil, and sand 

Sandy clay 

Red sand ; 

Thin bed of peat : : 

Sand stained with peat . : 

Dark peaty clay, more peaty below 

Peat, with sedges and hazel-nuts F : 

. Irregular bed of sand, coloured by peat, with a 
thin, irregular bed of gravel (1 to 2 inches), 
in other places a highly calcareous shell marl . if 0) 

9. Very thin beds of interstratified clay and sand. 3 0 
10. Gravel . : s : c : 3 : 5 0 
Mar! below. — 


EPNHOHOWwse 
=o 
BRON RAOB 


i 


1 About 30 feet below the surface in the gravels a deer’s horn was found. 
2 Vide The Geology of the Country between Derby, Burton-on-Trent, and Lough- 
borough, 1905, p. 64. 


A. R. Horwood—Post-Pleistocene of Central England, 547 


About 80 yards west the gravel is 3 feet nearer the surface. The 
fauna was as follows :— 


CRUSTACEA. Amphipeplea glutinosa.” 
Cypris. Limnea auricularia. 
L. stagnalis. 
GASTEROPODA. L. peregra. 
Segmentina nitida.' Velletia lacustris. 
Planorbis parvus. Bythinia tentaculata, 
P. contortus. Valvata piscinalis. 
Physa fontinalis. 


In a trench cut at Hay, peat, 6 to 9 inches thick, was found with 
hazel-nuts at the bottom, at a depth of 6ft. 7in.; and at Annesley 
Meadow at a depth of 2ft. 7in. in stiff clay, with a layer of 
vegetable mould 7 inches above; and in another section south-east of 
a large well belonging to Messrs. Bass, 45 yards from the River Trent, 
there was a layer of vegetable mould 6 inches thick succeeded by clay, 
with gome peaty matter (4 feet) changing into gravel coloured by peat, 
the peaty clay thickening towards the river. 


Derwent VALLEY. 


The lacustrine clay of Sinfin Moor is shown in the following 
section :— 


ft. in. 
1. Black peat : 9 iL 2 
2. Disintegrated shells - : : . F 0 3 
3. Stiff yellow clay . . : : : : 2 0 
4, Shells : : 5 é é ; : ya) 
5. Quicksand 3 @ 

8 5 


In the Erewash Valley the following plants, Crustacea, shells, etc., 
have been found and identified by Mr. Clement Reid, to whom the 
writer is indebted for assistance in the readiness with which he has 
been supplied with literature on this subject :— 


PLANTA. GASTEROPODA. 
Lycopod Spores: Limnea peregra. 
Scirpus lacustris. Bythinia tentaculata. 

CRUSTACEA. Valvata piscinalis. 
Daphnia Viviparus sp. 

INSECTA. LAMELLIBRANCHIATA. 
Chrysalis cases. Spherium corneum. 


At Allenton, near Derby, also in the Derwent Valley, Mr. Arnold 
Bemrose* found the following plants, with Hippopotamus, Elephas, 
Ehinoceros :— 


Ranunculus aquatilis. R. sardous. 

Lf. sceleratus. Viola palustris. 
R. flammula. Montia fontana. 
R. repens. Rubus ideus. 
R. ? bulbosus. Potentilla sp. 


1 Found in K. and W. Norfolk, Cambridge, Worcester, Montgomery, N. Lincs, 
S. and W. Lanes. 

2 The nearest counties where this is now found are: Kent, Berks, Bucks, 
K. Suffolk, KE. Norfolk, Huntingdon, N.E. and 8.E. York, N. Lincoln, Huntingdon. 

3 Quart. Journ. Geol. Soc., vol. lii, pp. 497-500, 1896. 


548 A. R. Horwood—Post- Pleistocene of Central England. 


Hydrocotyle vulgaris. 
Valeriana officinalis. 
Eupatorium cannabinum. 
Leontodon autumnalis. 
Taraxacum officinale. 
Ajuga reptans. 


Atriplex, 

Eleocharis palustris. 
Scirpus paucifiorus. 
Carex. 

Isoetes lacustris. 


According to Mr. Reid this flora is Interglacial, and it is 
undoubtedly Pleistocene, judging from the associated mammals, but 
we include it for comparison with the later floras. 


Hieuer Trent VALLEY. 


In the higher reaches of the River Trent, in alluvium of the 
tributary Cocker Beck, the following mammalia were recognized by 


E. T. Newton ! :— 


Human femur. 
Horse. 
Ox (? Bos longifrons). 


Sheep or goat. 


ig. P 
Dog or wolf. 


Mr. Clement Reid recognized in the silt the following plants :— 


Ranunculus aquatilis. 
R. flammula. 

R. acris. 

Fumaria officinalis. 
Arenaria trinervia. 
Spergula arvensis. 
Montia fontana. 
Prunus spinosa. 

P. padus. 

Rubus. 

Potentilla tormentilla. 
Apium graveolens. 
A. nodiflorum. 


Cornus sanguinea. 
Sambucus nigra. 
Carduus palustris. 
Solanum duleamara. 
Mentha aquatica. 
Galeopsis tetrahit. 
Stachys sylvatica. 
Chenopodium rubrum. 
Ttumex conglomeratus. 
Urtica dioica. 
Corylus avellana. 
Scirpus lacustris. 
Carex spp. 


The following shells were also found :— 


Pisidiwm pusillun. 
Spharium sp. 
Acanthinula lamellata. 
Carychium minimum. 
Clausilia cf. rugosa. 
CO. sp. 

Cochlicopa lubrica. 
Helix hortensis. 

HT. lapicida. 

HH. nemoralis. 

HI. pulchella. 
Limnea et. peregra. 
L. truncatula. 


Physa hypnorum. 
Planorbis nitidus. 
P. spirorbis. 
Pupa angliea. 

P. cylindracea. 
Pyranidula rotundata. 
Suceinea elegans. 
S. putris. 

Vertigo alpestris. 
V. antivertigo. 

V. pusilla. 
Vitrea cellaria, 


Peat and vegetable matter were noticed in sewer cuttings at old 
Basford in the Leen Valley ; and in peat at Old Radford, Quercus robur 
and Pinus sylvestris were observed by Mr. Shipman. At Clifton two 
teeth of Llephas primigenius were discovered 6 feet deep in brick-earth, 
and at Sneinton, close to Nottingham, a band of peat (12 to 18 inches) 
was found by Mr. Shipman, containing hazel-nuts and Bos longifrons. 


1 The Geology of the Country between Newark and Nottingham (Mem. Geol. Sury.), 
1908, p. 86. 


A. R. Horwood—Post- Pleistocene of Central England. 549 
South of the Trent the Thirlbeck River alluvium has yielded— 


Bythinia leachii. Planorbis marginatus. 
B. tentaculata. Spherium corneum. 
Hygromia hispida. S. rivicola. 

Linnea peregra. Unio sp. 


Planorbis complanatus. 


The Car Dyke alluvium also afforded— 


Bythinia tentaculata. Planorbis marginatus. 
Helix nemoralis, P. spirorbis. 
Hygromia hispida. Spherium cornewn. 


Limnea peregra. 


At Edwalton the following were found :— 


Bythinia tentaculata. Planorbis marginatus. 
Clausilia cf. rugosa. Pyramidula rotundata. 
Limnea palustris. Vitrea cellaria. 

L. pervegra. 


VaLe or Betvorr. 
The alluvium of the River Devon contains the following aoe — 


Bythinia tentaculata. Neritina sp. 
Hygromia hispida. Valvata piscinalis. 
Limnea palustris. Unio cf. pictorum. 
LL. peregra. 


In the late glacial deposits at Kirby Park the tooth of a mammoth 
was found, which is now in the Woodwardian Museum, and was 
figured by Leith Adams (‘‘The Brit. Foss. Elephants”: Pal. Soc., 
1879, pl. xiii). 

At Hose’ in brown loam freshwater shells are found in the Smite 
Valley. 

In Barnes’ brickyard north of Melton in the Eye Valley, at a depth 
of 9 feet in sand, boles and roots of trees, with bark and hazel-nuts, 
occur. Mammalian bones occur in gravel below this, including a human 
cranium, and bones and antlers of the red deer. 


Vater oF River WELLAND. 


The deposits differentiated in the area covered by old Sheet 64 were 
grouped by Professor J. W. Judd? as follows :— 


(1. Marine alluvium, warp of Fens. 


_ | 2. Alluvium of present rivers. 
s | 3. Alluvium of old fen lakes. 
‘'S | 4. Peat interstratified with marine silt. 
ws 4 &. Marine gravels of Fenland. 
4 | 6. Estuarine gravels. 
3 | 7. Low-level valley gravels. 
Fuels: High-level valley gravels. 


9. Cave deposits. 


He defined the glacial beds as— 


1. Glacial or Boulder-clay. 
2. Gravels. 
3. Sands. 


1 The Geology of the Melton Mowbray District and South-East Nottinghamshire 
(Mem. Geol. Sury.), 1909, p. 89. 
2 Geology of Rutland, 1875, p. 56. 


550 A. R. Horwood—Post-Pleistocene of Central England. 


But he admitted this was only a provisional arrangement, and much 
subsequent subdivision has been made.’ 
He classed as pre-Glacial the following :— 
1. Pebbly gravels and sands. 
2. Brick-earths. 


3. River gravels. 
4. Lacustrine deposits. 


In referring to the deposits mentioned below as pre-Glacial at 
Casewick, Mr. Clement Reid indeed regards them as Neolithic, but 
they may be, he says, ‘‘of older date.” He records Vuphar luteum, 
Galium aparine, Atriplex patula, Rumeax crispus, in addition to those 
given below. But we only here need consider those deposits in which 
land or freshwater mollusca occur, so that these modifications do not 
affect the case, for it is rarely that any molluscan remains are found in 
the Boulder-clay itself in the Midland area,” whilst the few instances 
of marine shells in the pre-Interglacial or post-Glacial beds are 
mentioned only to indicate where lacustrine and marine conditions 
alternated. 

It is in the lacustrine deposits alone that plants and shells have 
been found in the above area. Thus Professor Morris* discovered 
a freshwater deposit at Casewick in a hollow of the Kellaways rock 
covered in turn by glacial beds. The section was— 


ft. in, 

1. Gravel and sand in wavy seams. 2 ; eS 

2. Sand and gravel, with Belemnites, Gryphea, etc. 3 0 

3. Freshwater deposit, grey, sandy clay . : , 2 0 
4. Freshwater deposit, brown, sandy clay and veins of 

gravel . : - : ¢ . : : 6 

5. Freshwater deposit, peaty clay with plants and shells 176 


6. Freshwater deposit, dark sandy clay with plants and 
shells, with pebbles of chalk and flint and fragments 
of northern clay drift, the base being extremely 
irregular . : : 3 ; . . : 30 


18-19 0 


The plants, Crustacea, etc., were as follows :— 


PLANTA. Planorbis carinatus. 
Ceratophyllum demersum. Lf 2 umbilicatus. 
Equisetum. Limnea peregra. 

C Ancylus fluviatilis. 

BUSAN ACE Nc ‘ Velletia lacustris. 
Candona ? lucens (juv.). Bythinia tentaculata, 
C. reptans. ; Valvata piscinalis. 
Cypris (small species). V. cristata. 

GASTEROPODA. LAMELLIBRANCHIATA. 


Helix aculeata. 

HI. pulchella. 

H. hispida. 

Succinea putris. 
Carychium minimum. 


Spherium corneum. 
Pisidium amnicun. 

P. amnicum, var. puichella. 
P. pusillum. 

P. pusillum, var. obtusalis. 


1 R. M. Deeley, Quart. Journ. Geol. Soc., vol. xlii, p. 487, 1886. 

2 At Beasley’s Pit, Aylestone, Mr. G. W. Lamplugh and the late C. Fox 
Strangways found Zellina balthica. ay 

3 Quart. Journ. Geol. Soc., vol. ix, p. 321, fig. 2, 1853. 


A, R. Horwood—Post- Pleistocene of Central England. 551 


In addition to these contemporary species were derived fossils from 

the Oxford Clay— 
Cerithiun. Echinus. 
Area. Other marine remains. 
Belemniies. 

A comparison between the proportional number and the species 
represented in these pre-Glacial deposits and those found. in the 
post-Glacial beds shows how very similar in species and general 
character the periods preceding and following the Glacial Period were. 
If we regard these pre-Glacial beds as really mid-Glacial or Inter- 
glacial the comparison is equally interesting. 

Another bed 3 miles to the west:in the River Gwash Valley 
contains land shells and bones, being possibly slightly later. In 
the deposits actually assigned to the Glacial epoch no contemporary 
molluscan remains were noticed by Professor Judd. 

Passing to the post-Glacial deposits, with which we are more 
directly concerned, the only cave deposits are those at Tinkler’s 
Quarry, Stamford. Professor Rolleston identified the following :— 

Hyena (teeth). Cervus megaceros (tooth). — 
Elephas (tooth). Cervide, various. 

This cave was said to have been 15 to 20 feet square, and was 
doubtless a hyzena cave to which prey had been conveyed. The long 
bones were broken and some had been gnawed. 

In the overlying valley gravels, locally in thin sandy loam, molluscan 

remains occur, but are not common, whereas mammalian remains are, 
including living and extinct types intermingled, as Llephas, rhinoceros, 
hippopotamus, hyena, horse, red deer, and urus. No flint implements 
had been found at the time in these gravels. Above these a loam, 
like the loess, containing remains of living terrestrial shells, occurs 
near Peterborough. Mammalian remains occur in gravel at Helpston, 
including the Mammoth. 
_ In the estuarine gravels both freshwater and marine shells occur 
at Peterborough, and at Overton Waterville the following: Ostrea 
edulis, Cardium edule, and the land and freshwater species Planorbis 
carinatus, Limnea glutinosa, Ancylus fluviatilis, Bythinia tentaculata, 
Pisidiumamnicum. The following mammalian remains were associated 
with them: Llephas primigenius, Rhinoceros tichorhinus, Equus caballus, 
Canis lupus, Hyena spelea, Cervus elaphus, Bos primigenius. 

Limnea (Amphipeplea) glutinosa, an extremely local species, is still 
found in South Lincolnshire and in Northampton, Kast Norfolk, 
Bucks, Berks, and East Kent, but is otherwise rare. 

In the marine gravels of the Fenland the fauna includes mollusca 
and mammalia, viz.: Zittorina littorea, Turritella communis, Buccinum 
undatum, Tellina solidula, Ostrea edulis, Mytilus edulis, Cardium edule, 
Cyprina islandica. This last, though now rare, is still found in the 
North Sea. The peat, and marine silt which is interstratified with it, 
contains a diversified flora and fauna. In the peat, made up largely 
of Sphagnum and other bog-mosses, stools of trees are found, e.g. oak, 
birch, etc. These are often found washed out and waterlogged along 
the Lincolnshire coast. Of mammals the following occur: Bos primi- 
genius, var. longifrons, Irish elk, wild boar, red deer, bear, otter, 


552 <A. R. Horwood—Post- Pleistocene of Central England. 


beaver, wolf, fox. In the buttery clay marine shells occur, viz. : 
Ostrea edulis, Cardium edule, Scrobicularia piperata. Foraminifera 
have also been found, and remains of marine mammals, whale, and seal 
are not uncommon. 

In the alluvium of the Old Fen lakes or meres of Whittlesea, 
Ramsey, Ugg, etc., the alluvium or silt is crowded with Unio, 
Anodon, Paludina, Planorbis, Limnea, forming a shell marl. The 
alluvium of the present rivers contains also a considerable flora 
and fauna, and consists of black loam or silt, reformed by modern 
rivers, and continually being augmented year by year. In the Nene 
and Welland valleys these are very extensive. In the Fens the 
marine alluvium or warp is found near Crowland, and resembles the 
silt found associated with peat at a lower horizon. 


VALLEY oF River Nene. 


an a fissure of the Lincolnshire Oolite at Brigstock, Mr. A. Wallis 
found recent land and freshwater shells, and Mr. Beeby Thompson! 
explained their occurrence as due to ‘disturbance of Lincolnshire 
Oolite and redeposition with introduction of the shells at the time of 
the latter. He suggests their pre-Glacial age, and preservation in 
Interglacial clay. This would lend support to the earlier age of the 
shells at Casewick, also in a fissure. In a later paper Mr. Beeby 
Thompson? includes these shell deposits in the late mid-Glacial 
gravels, which underlie the Upper or Chalky Boulder-clay. 

The shells that were found were— 


Succinea putris. Helix nemoralis or arbustorwn, 
Cochlicopa lubrica. Pupa marginata. 
Helix pulchella. Pisidium pusiliun. 


- In valley gravels lephas antiquus, E. primigenius, Rhinoceros 
tichorhinus, R. leptorhinus, Hippopotamus major, Equus caballus, Bison 
priscus, Bos primigenius are found, tusks and teeth in the upper 
part of the Nene Valley, lower down near Peterborough marine shells, 
Cardium and freshwater species of Physa, Limnea, Planorbis. At 
Elton and Northampton Mammoth occurs. 

In river alluvium at Martin’s brickyard Mr. H. N. Dixon * found— 


Nuphar luteum. Polygonum. 

Stellaria media. Mercurialis perennis. 
Prunus spinosa. Alnus. 

P. padus. Corylus avellana. 
Sambucus nigra. Quercus robur. 


Mammalia, Bos longif/rons and B. primigenius, horse, sheep, wild 
hog, red deer, freshwater mollusca, and human remains, often coated 
with vivianite, also occur. 

For comparison with localities farther removed from the central 
tract of Leicestershire, we add a list of plants, etc., found outside the 
midland or central tract. At Dursley, Gloucestershire, to the south- 
west, a calcareous tufa in process of formation is full of leaves. 
Miss M. A. and Mr. Clement Reid‘* found leaves of hazel, elm, and 
hart’s tongue in it. 


' Grou. Maa., 1895, pp. 1-3, reprint. 2 Proc. Geol. Assoc., 1910, p. 485. 
5 The Origin of the British Flor a, Clement Reid, F.R.S., 1899, p. 138. 
* Thid., p. 66. 


Eo 


Professor J. B. Harrison—‘ Laterite’ in British Guiana. 5538 


At Wolvercote, near Oxford, to the south, in an alluvial deposit 
lying over Paleolithic implements and bones of Bison, the following 
were found :—' 


Ranunculus aquatilis. Heracleum sphondylium. 
LK. sceleratus. Potamogeton. 

R. repens. Eleocharis palustris, 
Potentilla tormentilla. Scirpus lacustris. 

Viola. Carex rostrata. 


Hippuris vulgaris. 


Compared with results obtained in Scotlund and East Anglia, the 
record of life in the post-Pleistocene deposits of Central England is 
meagre, and shows what needs yet to be done. The survey of the 
localities where material has been found, in this summary, may have 
the desired effect of stimulating further investigation. 

As regards glacial deposits, it is probable that careful examination 
of accumulations such as the quartzose sand with interstratified 
carbonaceous layers may have good results. 

The occurrence of several species of living land and freshwater 
shells in the mid-Glacial gravels, at Brigstock and at Casewick (not 
certainly of this age at the last locality, but probably), lends support 
to the pre-Glacial origin of the prototypes of our land and fresh- 
water mollusca. The known existence of many of the plants found 
with the mollusca in pre-Glacial times, e.g. Ranunculus aquatihe, 
R. sceleratus, R. repens, Nuphar luteum, Stellaria media, Prunus spinosa, 
Heracleum sphondylium, Atriplex patula, Betula alba, Alnus glutinosa, 
Corylus avellana, Quercus robur, Ceratophyllum demersum, Pinus 
sylvestris, Alisma plantago, Eleocharis palustris, Scirpus lacustris, 
Isoetes lacustris, etc., lends support to this notion. Moreover, the 
universal distribution of certain species of mollusca throughout this 
central region is also evidence of their greater antiquity, viz. :— 


Hyalinia cellaria. Limnea peregra. 
Helix pulchella. LL. auricularia. 

H. hispida. L. stagnalis. 
Cochlicopa lubrica. Ancylus frwiatilis. 
Suceinea putris. Bythinia tentaculata. 
Planorbis spiror bis. Valvata piscinalis. 
P. umbilicatus. Spherium corneum. 
Physa fontinalis. 


To this may be added the homogeneity, in general, of the 
mammalian fauna found in association with both the plants and 
other animals of the post-Pleistocene deposits. 


V.—Txue Resipvat Eartus or British GUIANA COMMONLY TERMED 
‘LATERITE ’. 


By Professor J. B. Harrison, C.M.G., M.A., F.G.8., F.I.C., assisted by 
K. D. Rerp, Assistant Analyst British Guiana. 


(Concluded from the November Number, p. 495.) 


WE losses of their constituents during the decompositions of the rocks.— 
As shown in this paper the analyses of the rocks and of their decom- 
position-products do not indicate the extent of the degradation which 


1 The Origin of the British Flora, Clement Reid, F.R.S., 1899, p. 61. 


904 Professor J. B. Harrison—‘ Laterite’ in British Guiana. 


has taken place. To ascertain this it is necessary to re-calculate the 
analytical figures so that their proportions are comparable to those of 
one of the constituents which is assumed to have remained unchanged. 
The structures of the Surinam and the British Guiana bauxitic laterite 
show clearly that, contrary to what is not unfrequently assumed, 
alumina cannot be regarded as a static component in rocks and their 
decomposition-products. It is evidently under condition of lateritiza- 
tion capable of entering into solution, transference from place to place, 
and redeposition in the form of alumina hydrate where conditions are 
favourable. The constituent which appears to be the most stable 
under conditions of weathering is titanium oxide, especially that 
present as ilmenite. But unfortunately as a rule it is present in such 
low proportions in rocks and in their residuary products that, when 
taken as the static constituent, errors in analysis of low value are 
productive of variations of wide extent in the results calculated 
on them. | 

When calculations of this sort are made on the epidiorite of Issorora 
and on the lateritic earth with its enclosed pisolites the difficulty 
arises that the iron in the earth and in its enclosed pisolites has not 
been derived only from the portion of the rock which has given rise 
to the earth, but is largely an infiltration product from other lateritic 
earth which has been removed by denudation. 

The results calculated on titanium oxide as the static constituent 
are as follows :— 


Taste XVIII. 


Original Karth with 
Epidiorite. Pisolites. 

Silica . r . : ; : 49°06 (Pill 
Aluminium Oxide . : F ; 18°87 10°69 
Iron Protoxide . é 5 ; 6°38 
Tron Peroxide ; : : ; 21-26 
Magnesium Oxide . : 0 : 10°95 21 
Calcium Oxide . 3 A é 11:70 oil i 
Sodium Oxide ‘ ; i ‘ ‘97 “02 
Potassium Oxide . : ; ‘ “06 “09 
Water . ; 3 : : : 43 3°66 
Titanium Oxide . : : ; “88 “88 
Manganese Oxide . ; ; < 34 01 

99-64. 44-44 


The excess of iron, the increased amount of water, and the gain 
in weight of the oxidation of the protoxide of iron in the original 
rock being eliminated, it is seen that of 100 parts of the constituents 
of the epidiorite only 26:4 remain in the laterite and that therefore 
a loss of 73°6 per cent. of the epidiorite has taken place. This loss 
falls on its constituents in the following proportion shown as losses 
per 100 parts of each :-— 


TABLE XIX. 
Silica . : : ‘ : : 84°7 
Aluminium . 2 - ‘ é 43°4 
Magnesium Oxide . 5 : : 98-1 
Calcium Oxide , : f 5 99-1 
Sodium Oxide : : E Z 97:9 


Manganese . 3 ; : 97 


os 


Professor J. B. Hurrison—‘ Laterite’ in British Guiana. 


dD9 


Similar calculations based also on the assumption that the titanium 
oxide is the static constituent have been made with regard to: the 
Tumatumari, Omai Falls, and Mazaruni laterites. 


given in Table XX— 


Their results are 


TasBLe XX. 
Tumatumari. Omai Falls. Mazaruni. 
Diabase. | Laterite. | Diabase. | Laterite. Hornblende Laterite. 
Schist. 
Silica . Ba, si19 | 3043 | 53-25 | 29-90 | aio | 15°84 
Aluminium Oxide . 15°80 15°80 17°16 11°78 15°94 11°38 
Tron Protoxide . 14°28 12°53 14°40. 
Tron Peroxide ; 6°40 14°30 2°55 
Magnesium Oxide . 5°63 13 6°10 08 5°54 704 
Calcium Oxide . 9°58 14 7:46 07 9-60 “003 | 
Sodium Oxide 2°09 “08 2°50 -10 1°87 °18 
Potassium Oxide 60 <x, 69 0 | 08 16 
Water ; 30 | 6°77 30) |MieiODM AIMCO 3 
Titanium Oxide . “40 | “40 39) +39 | -30 30 | 
| | at 
99°87 | 60:27 | 100°33 63°87 99°73 33°453 


Allowing for the gain in water in each of them, for the oxidation 
of the protoxide of iron, and for a small excess of iron peroxide due 
to infiltration in the Omai Falls sample, we have losses of 47°4, 44°6, 
and 70°5 per cent. respectively of the original rocks during their 
degradation to laterite. The loss per 100 parts of each constituent of 
them is as follows :— 


TABLE XXI. 

Tumatumari. Omai Falls. Mazaruni. 
Silica . z 5 : 40°5 43°6 69°3 
Aluminium . ? : nil 31°3 28-6 
Tron Peroxide ‘ : 58°7 nil 83°6 
Magnesium Oxide oiler 9827 ~99-2 
Calcium Oxide . : 98°5 99°1 99°9 
Sodium Oxide F é 9671 96 90°4 
Potassium Oxide . , 80 47°8 nil 


The range of variation in the losses of alumina and oxide of iron is 
wide, being for alumina from m2 to 31-3 per cent. and for oxide of iron 
from nz to 83°6 per cent. 

The most interesting points in the above results are the great loss 
of combined silica and the change of some of the silica set free into 
quartz. Thus, in the Tumatumari sample 46-01 of the combined 
silica present in the rock is not found in that form in the derived 
laterite, but 25-2 of the silica set free has been changed into quartz ; 


in the Omai Falls sample 41-7 of the combined silica has disappeared, 


leaving in its place 18°2 of quartz; and in the Mazaruni sample 39-1 
of the combined silica has been apparently lost from that condition, 
whilst only 3°2 of it remains as quartz. 


556 Professor J. B. Harrison—‘ Laterite’ in British Guiana. 


The following changes are indicated as having occurred during the 
degradation of the granite and the hornblende-granites at Mazaruni 
and Mahdia :— 


Taste XXII. 
! 
| Mazaruni. Mahdia. 
: ; Hornblende : 
| Granite. | Pipe-clay. Granite: Pipe-clay. 
| | 
Silicamne haste ae 73°81 49°61 68°20 29°04 
Aluminium Oxide. . | UC | || 14°47 15°83 11°30 
Iron Peroxide . . . | PATS) WSS K oket9 3°43 1-21 
Magnesium Oxide. . | 72 07 2°14 18 
Calcium Oxide. . . *88 | nil 3°49 04 
Sodium Oxide. . . | 2°80 -28 3:07 nil 
Potassium Oxide . . | 4:81 | “36 2°88 18 
IWiateia: viieray tts talons “74. | 6°22 “50 3°15 
Titanium Oxide . . 62 ! "62 46 *46 
| 
| 
G07 2 yl aeengecke 100 45°56 


Allowing for the added water in each and for slight apparent 
increases in the alumina and iron oxide of the Mazaruni specimen, 
there is a loss of 33 per cent. of the constituents in the case of the 
granite and of 54°5 per cent. in the case of the hornblende granitite. 
The losses in each 100 parts of the various constituents work out 
as follows :— 

Taste XXIII. 


Mazaruni. Mahdia. 

Silica 3 ‘ : : 32°8 57°4 
Alumina .. : A ; nil 28-4 
Tron Oxide. ; : nil 64:7 
Magnesium Oxide ; : 90°3 91°6 
Calcium Oxide . e : 100 98°8 
Sodium Oxide . i A 90 100 

Potassium Oxide . ‘ 92°5 97°2 


In the cases of the conversion of the rock into pipe-clay there are 
apparent losses of silica present as quartz as compared with the 
amount calculated to be present in the granite and the hornblende- 
granitite. ‘This is due to re-arrangement of the material by washing, 
which has separated the finer particles from the coarser ones, which, 
as a rule, form coarse sands to fine angular gravel on the surface 
of the pipe-clay. 

In the foregoing description of the British Guiana lateritic earths 
and their components, I have confined myself to the laterites which 
are in situ, and have not described the so-called low-level laterite or 
the ‘‘Alluviale Laterit or Sekundare Laterit’’ of G. C. Du Bois, 
which he defines as ‘‘ Aluminous Laterit” or as the ‘“‘ Alluvium yon 
Lateritdetritus ’’. Where I have seen alluvial deposits of this nature 
in British Guiana they have been mixed to such an extent with the 
detritus from granitic rocks or even from clastic rocks that they have 


Professor J. B. Harrison—‘ Laterite’ in British Guiana. 557 


not, in my opinion, a right to the term laterite. But I have shown 
in connexion with certain of the laterites I. have described how 
readily aluminous deposits can be formed from normal lateritic earths 
by ordinary processes of elutriation and redisposition. The accurate 
and complete account of the ‘‘ Alluviale Laterit” of Surinam by 
Du Bois is fully applicable to those of British Guiana. But personally 
Ido not apply the term laterite to these detrital deposits, which are 
equally well described as valley or river alluvia. 

I have also not described the deepest layers of the residual deposits 
which are met with in the shafts of mines below the water-table and 
closely overlying the unaltered rock. They do not, as far as my 
limited experience goes, show the characteristics to any marked 
extent of laterite either according to Buchanan’s description or to. 
more recent views. They are best described as decomposed diabase, 
gabbro, or schists as the case may be, as they largely consist of 
partially decomposed fragments of these rocks with varying amounts 
of secondary quartz, hydrates of alumina and iron, and kaolinite 
derived in part from the decomposing rocks or washed in from 
overlying lateritic earths. . 

Where the original rocks are massive and compact, are only covered 
with comparatively thin layers of lateritic products, and are practically 
above the water-table, the transition from unaltered rock to lateritic 
earth is abrupt, and few, if any, particles of the original rock, except 
grains of ilmenite and of similar highly resistant mineral, can be 
found in the residual earths lying directly in the rock. 

The Laterite of Surinam and of French Guiana.—The ferruginous 
residual earths in South America appear to have attracted the notice 
of geologists and mining experts in these countries from quite early 
periods; for example, amongst other early authors they are mentioned 
by J. B. Le Bland, Deseription de la Guyane Francaise, 1814; 
y. Eschwege, Bettrdge zur Gebirgskunde Brasiliens, 1832; Schomburgk, 
Reisen in Guyana und am Orinoko, 1841 ; Heuser, Beitrag sur Kenntnis 
des brasilianischen Kiistengebirges, 1858; Le Neve Foster, ‘‘ Caratal 
Gold-field” (Q.J.G.8., No. 99, vol. xxv, pp. 840-2); and Tate, ‘‘ Geology 
of Guyana Venezuela” (Q.J.G.S., No. 99, vol. xxv, pp. 349 and 350). 

Among more recent works in which more or less detailed accounts 
of the laterites of Surinam and French Guiana are given are: Martin, 
Reise nach Niederlindisch -Westindien, 1888; levat, Recherche et 
Pexploitation de Vor en Guyane Francaise, 1898; Du Bois, Geologisch- 
bergminnische Skizzen aus Surinam, 1901; van Cappelle, La constitution 
géeologique de la Guyane hollandaise, 1907; whilst the most complete 
account of the Surinam laterites is Du Bois’ monograph Bettrag zur 
Kenntnis der Surinamischen Laterit, 1908, to which I have several 
times referred. 

Unfortunately for the purposes of this paper the analyses given by 
the above authorities are more or less incomplete owing to the silica 
present in the form of quartz not having been determined separately 
from that present in the combined state. The analyses of ‘‘ Roche 
a& Rayvet”’ given by Levat on p. 42 of his work show that, even if 
all the silica was present in the combined state, the samples from 
Maripa would have contained 7°6 per cent. and those from Awa 


558 Professor J. B. Harrison—‘ Laterite’ in British Guiana. 


7'7 per cent. of alumina in the state of hydrate. In the majority 
of the analyses of concretionary ironstones given by Du Bois it is 
not possible to demonstrate the presence of free aluminium hydroxide, 
but his analyses of an alluvial one show that at least 5:2 per cent. of 
alumina is present in the form of hydrate. 

The fact that bauxite or gibbsite is found in the laterites of Brazil 
and of the Guiana has been known for many years. R. Hermann, in 
1869 (Journal f. prakt. Chemie, vol. i, p. 72), described hydrargillite 
which occurred in the laterite of Villa Ricca in Brazil, whilst its 
occurrence in French Guiana was recorded in 1878 by Jannetaz in the 
Bulletin de la Société Minéralogique de France, vol. i, p. 70. The first 
full description of typical bauxitic laterite from Surinam is that given 
by Du Bois, pp. 84-7 of his monograph on the laterite of that colony. 
He there gives the following ‘ technical’ analyses :— 


Taste XXIY. 


x XI XII 
Alumina . 63:3 48°5 §2°5 
Tron Peroxide 10°5 21°6 14°4 
Silica : i 14°45 ee Sil 
Calcium Oxide . 2 ; 1 1 1°5 
W ater ; : : ‘i 17°6 14 27°6 

99-4 99-6 99-1 


Du Bois specifically states that the silica is present in them in the 
form of secondary chalcedony. If all of it is so present the bauxite 
contains from 48.5 to 63°3 per cent. of free alumina or from 62°5 
to 80°9 per cent. of aluminium hydrate, whilst the lowest pro- 
portion of alumina that can be present in the uncombined state on the 
assumption that all the silica is combined with alumina will vary from 
40 to 57 per cent. 

The studies which have been made in the Guianas by Du Bois, 
Levat, Lungwitz, van Cappelle, myself, and others, both in the field 
and in the laboratory, show that certain residual deposits derived 
mainly from rocks of the diabase-gabbro, diorite, and porphyrite types 
which contain predominantly felspars of the albite-anorthite series 
have full right to be termed laterite both in the restricted sense of the 
term advocated in this journal by Dr. Evans and Mr. Crook and in 
the wider meaning originally ascribed to it by Buchanan; that masses 
of bauxite occur in residual earths of complex composition which 
cannot be described as characteristically aluminous, as they are usually 
to more marked extents siliceous or ferruginous, although they in- 
variably contain more or less hydroxide; and that the concretions in 
the residual earths vary from concretionary ironstones to impure 
ferruginous bauxite.’ 

I have only seen the laterite in one district of Surinam where it 
formed a covering to a greatly metamorphosed sericitic schist. Here 
there is a gradual change of the decomposing schist into its laterite, 
the change extending to considerable depths in the schist. The 
lateritic earth, covered in places by concretionary masses of ironstone, 

1 In the Guianas the formation of masses of bauxite appears to be due to later 


segregation changes in the metasomatic residual earth rather than to the completeness - 
of the original decompositions. 


Professor J. B. Harrison—‘ Laterite’ in British Guiana, 559 


reminded me of Logan’s account of the ferruginous and silico-ferru- 
ginous rocks and laterite of Singapore (Q.J.G.S., vol. yi, p. 331, 1851), 
and of Mr. Scrivenor’s description of the laterite of the Malay 
Peninsula (Grotocicat Macazinr, September, 1909, No. 543, p. 431). 

The view that I have formed after many years’ fairly intimate 
acquaintance with the Guiana residual deposits in the field and in the 
laboratory is that the terms laterite or lateritic earths are both useful 
and convenient ones to denote the whole mass of the residual deposits 
which are characterized by the occurrence in them of concretionary 
masses varying from highly ferruginous to highly aluminous, as well 
as, in places, by the presence of secondary silica in quantity. In 
my opinion laterite of the above nature can be accurately defined, 
following Du Bois (p. 3 of his monograph), as the weathering 
product of igneous or metamorphosed rocks in which by chemical 
decomposition the silicates contained in them have been changed to 
secondary siliceous compounds, secondary silica and alumina, and to 
oxides of iron in more or less hydrated forms. Following Mr. Scrivenor 
the laterite can be conveniently classed into siliceous, ferruginous, or 
aluminous laterite as its composition indicates, whilst the highly 
aluminous masses present in them can, in my opinion, be best and 
most accurately described as bauxite. The above definition would 
cover not only the aluminous masses to which it has recently been 
proposed to restrict the term laterite, but also the great majority of 
these which possess, in parts at any rate, that property of setting 
from which the name was originally derived. It would also cover the 
residual lateritic deposits of varying compositions, due to climatic and 
other conditions, found in different parts of the Indies. 

It is not possible in the Guianas to ascribe the production of 
lateritic deposits to regular alternation of dry and wet seasons. 
Du Bois gives a table in his work from which I have calculated 
in inches the average monthly rainfall in Paramaribo, Surinam, for 
the years 1896 to 1901. This and the average monthly rainfalls 
during sixteen years at stations in British Guiana situated on laterite 
are shown in the following :— 


TABLE XXV. 
Surinam. British Guiana. 
Paramaribo. Mean of 10 inland 
1896-1901. stations on I.aterite. 
1891-1906. 
Inches of rain. Inches of rain. 
January. : : : 5°24 7°06 
February. : : : 5°61 4-29 
March P F : ; 8:65 7°22 
April . 5 : : : 8 39 8 
Nia? See eco ae aie ea 12-25 11:89 
June . ; : 4 - 11°65 12°45 
July . : > : é 6°37 10°69 
August . : ‘ - 5°49 7°96 
September . ‘ ; . 2°66 5°22 
October i 4 : : 3°45 4:93 
November . : : : 7 6°57 
December . 3 : 5°49 10 


82°25 95°58 


560 Professor J. B. Harrison—‘ Laterite’ in British Guiana. 


In the dense forests of the Guianas there may be said to be 
a perpetual wet season, as under the shade of the trees even during 
periods of comparative drought the land is invariably wet and more or 
less soaked with water containing organic acids in solution. 

The only factor indicated in the Guianas as governing the production 
of lateritic deposits as opposed to that of pipe-clays is the original 
composition of the rocks. Rock in which plagioclase felspars with 
their usual concomitants of ferro-magnesian minerals are abundant, 
give rise by their decomposition in situ to laterite; those in which 
alkali felspars are predominant as a rule decompose to pipe-clays or 
kaolins. 

The protective influence on the soils of the very heavy tropical 
forests which in the Guianas specially characterize the areas of 
lateritic residual deposits is very great. When the land is cleared 
of forest denudation rapidly removes the fine constituents of the 
earths, leaving on the surface the masses of ironstone, bauxite, and 
quartz. The Christianburg-Akyma deposits show that under conditions 
of which we have no indication a lateritic decomposition-product may 
differentiate into angular secondary quartz-sand and into concretions 
and impregnations of secondary hydrates of aluminium and iron. 

It has been repeatedly stated that the production of laterite is 
confined to countries having hot, moist climates. Positive evidence 
as to this appears to me to be wanting. That the preservation of 
lateritic deposits is largely confined to more or less tropical countries 
I willingly admit, as it is the absence of frost that allows of the 
accumulation of deep deposits of laterite. The property of hardening 
or setting when exposed to the atmosphere which these deposits 
exhibit in parts, although sufficient for their protection under tropical 
conditions, would be of little effect were the deposits exposed to 
frost. Under temperate conditions the accumulation of laterite in 
situ to great depths would be more or less impossible ; the residuary 
matters would be subject to rapid detrition and denudation, their 
hardening properties would not be developed or only to a slight 
extent, and what under tropical conditions would form laterite would 
be redeposited as alluvial detritus, in which the presence of free 
hydrate of alumina would not be easily recognized. 

The majority of the analyses which have been made of such 
alkaline deposits have been for agricultural purposes, and in such 
analyses, unless the attack of the dilute acid used is continued for 
a great length of time, a considerable proportion of the alumina, 
which is in the form of hydrate, which is resistant to a marked degree 
to the action of weak acids, will not enter into solution and will be 
included amongst the sand and insoluble silicates. It is therefore 
possible that the proportions of alumina present as hydrate have been 
underrated in many analyses of the clays and earths of temperate 
countries, and that if analyses were carried out on lines adapted for 
the determination of the proportion of silica present as quartz, or 
colloid silica, and in the combined state and of the total amounts 
of alumina and other bases present, earths with noticeable proportions 
of other hydrates of alumina would be found not to be of rare 
occurrence. In connexion with the possible presence of alumina 


Professor J. B. Harrison—‘ Laterite’ in British Guiana. 561 
a 


in the form of hydrate in the earths of temperate countries the 
investigations by Liebrich of the occurrences of bauxitic material 
in the Vogelberg and Westenwald (Zeitschrift fir Krystallographie 
und Mineralogie, xxiii, p. 296, 1894, and Chemisches Centralblatt, 
1892, p. 94), where the bauxite was proved to be a decomposition- 
product of a basaltic rock, and the recent paper on the same subject 
by J. R. Kilroe (Gon. Mag., No. 534, p. 534, December, 1908), may 
be of interest. 

My long experience in the Tropics with igneous rocks and their 
decomposition-products has satisfied me that all questions relating 
to the degradation of the rocks and the re-arrangement of their 
decomposition-products may be accounted for by the normally 
occurring, practically unlimited factors of water, carbonic acid, 
decomposition-products, including organic acids of vegetable debris, 
and, above all, duration of time. Geologists and possibly chemists 
are apt to underrate the decomposing, ionizing, or mass action 
exerted by even pure water on rocks during very prolonged periods 
of time—periods which on the geologically very ancient land of the 
Guianas may have extended over geological ages.? 

There is no necessity for calling in the aid of the very small 
quantity of nitric acid supplied by the rainfall, which in British 
Guiana has amounted to only 9 pounds of nitric acid (H NO.) per 
acre per annum according to our monthly analyses of the rainfall 
carried on continuously for over twenty years. Nor are the small 
quantities of sulphuric and sulphurous acids derived from the 
oxidation of pyrites of importance, as in British Guiana pyrites is only 
present in appreciable quantity in metamorphosed rock, whilst in 
masses, dykes, and sills of diabase on which wide areas of laterite 
occur, its presence is practically confined to narrow selvages of the 
contact rock in even minute quantities. 

As far as the studies made in the Guianas go it appears that the 
cause of the hardening or setting of certain laterites will not be found 
by chemical analysis. My personal opinion is that it is due in part 
to changes in the degree of hydration of the hydrated oxides of iron 


' Some ten or eleven years ago, whilst lecturing on agricultural science, I used the 
following experiment to illustrate the action of pure water on rock. Rock powder 
was prepared from various types of rock by grinding on a bucking plate. About 
twenty grams of the rock powder was placed in a beaker, and from 100 to 150 ce. 
of cold, recently distilled water poured on it. To the water thus freed from carbonic 
acid a few drops of a solution of phenol-phthalin was added. In the course of 
a few minutes the water commenced to change to purple, and after ten minutes or 
so had elapsed the depth of colour produced served as a measure of the rates of 
decomposition of the various rocks by the water. I found that the most readily 
decomposable rocks were felspar-porphyry and porphyrite, the next being granitite- 
gneiss, followed by granite and granitite. The basic rocks were more slowly attacked 
by the water. After standing for some time when the colour of the water had 
ceased to deepen it was then poured or filtered off completely, the rock powder again 
treated with fresh quantities of the boiled water or in phenol-phthalin, when the 
gradual colourization again ensued. This, if desired, could be repeated many times, 
using the same rock powder. The experiments well illustrated the action of water 
free from carbonic acid on the rocks, and its ‘repetition with successive quantities of 
water show it to be a mass action. The rates of decomposition of the various rocks 
thus indicated were found to correspond with the extent of their denudation and 
degradation on the lower-lying lands of the colony. 


DECADE Y.—VOL. VII.—NO. XII. 36 


562 C0. Johns—Classification of the Lower Carboniferous Rocks. : 


and aluminium present and to the gradual conversion of soluble 
colloidal forms of alumina, of iron peroxide, of silicate, and possibly 
of certain silicates with insoluble modifications during the exposure 
of the rocks to the atmosphere. The deposition of the hydrated 
oxides of iron from the dissociation of naturally produced solutions of 
carbonate of iron is doubtless in many places also a factor in the 
induration of the laterite in situ. 


WEATHERING AND Decomposition oF Rock anp Soits In THE TROPICS. 


In his investigations on weathering of rocks in the Tropics, Mr. E. C. J. Mohr 
(Bul. Dept. Agr. Indes Neerland, No. 32, pp. 26, figs. 2, 1909) records the effect of 
rain-water on freshly ground Tertiary basalt under moist warm climatic conditions 
as follows :— 

The rock was used in three sizes, + to 4, 1 to 14, and 3 to 4mm. particles. It 
was subjected to the action of rain-water from July, 1906, to December, 1908, in 
an apparatus so arranged that in one series the level of the water was above that of 
the rock particles, and in the other the particles were kept moist by rise of water 
from below. ‘The principal fact noted in the first series was that the silicic acid 
corresponding to the decomposed augite and lime felspar was washed out with the 
soluble bases, while the silicic acid corresponding to the alkali felspar remained 
behind as kaolin. In the second series, only the silicic acid corresponding to 
decomposed augite was removed, and the silicic acid corresponding to lime felspar 
remained behind. (Experiment Station Record, vol. xxii, No. 8.) 

Note. Owing to a copyist’s error, the figures 8°26, against ‘‘ Iron Protoxide’’, 
incorrectly appear in the analysis of the ‘l'umatumari Laterite (in Table IV on 
p. 446 of the October number of the Gon. Magc.), and should be deleted, the 
summation of the analysis being carried out as 100-45, the correct figures. 


VI.—On tHe Crassirication oF THE Lower Carponirerous Rocks. 
By Cosmo Jonns, M.I.Mech.E., F.G.S. 
N this communication it is proposed to briefly note the divisions 
which have been proposed for the Lower Carboniferous Rocks of 
Great Britain and Belgium; to discuss their validity in the light of 
the important additions that have been made to our knowledge during 
the last few years; and to suggest a new classification which, while 
expressing the physical and faunal changes which characterized that 
particular time interval, shall be generally applicable and at the same 
time do justice to the workers who have contributed most largely to 
our knowledge. 

It will be necessary to clearly define what is meant by the Lower 
Carboniferous. In Staffordshire, Derbyshire, and North-West Yorkshire 
the line has been drawn at the base of the Ingleborough or Kinderscout 
Grit or its equivalent. In Scotland the Roslin Sandstone is the 
dividing line, and in the first and last of the areas mentioned 
Mr. Kidston! has determined the great break between the Upper and 
Lower Carboniferous lloras to take place at this level. In Derbyshire 
and North-West Yorkshire a marked change of conditions occurs at 
the same level, and the Geological Survey in both places drew the 
line at the base of the massive Grit. By definition, therefore, Lower 
Carboniferous extends up to the level where the plant break occurs. 
No one has suggested extending the limits any higher, and to draw 
the line at a lower level would divorce the Upper Yoredale limestones 
with their rich coral and Brachiopod fauna from the lower limestones 


1 See Mem, Geol. Surv. Derby. and Notts. Coal-field, 1908, p. 9. 


C. Johns—Classification of the Lower Carboniferous Rocks. 563 


with which they are faunally and physically linked. There should 
be no difficulty in selecting a name for this great division of the 
Carboniferous System. The work that has been done by Dr. Arthur 
Vaughan on the Avon section, and the impetus which the publication 
of his conclusions gave to the study of the Carboniferous Limestone in 
this country and abroad, at once suggests the acceptance of the term 
Avontan in preference to Bernician or Dinantian. 

For the divisions of the Avonian we have in common use the terms 
Tournaisian and Viséan. If only in fairness to the Belgian workers 
who established these divisions, and in recognition of the value of their 
contribution to our knowledge, these terms should be retained. It has 
been demonstrated ' that the line drawn in Belgium corresponds exactly 
to the physical break in South Wales at the base of the Viséan, and 
is the well-known C-S level of North-West Yorkshire and Westmore- 
land. Thus the dividing line between Tournaisian and Viséan is, and 
can only be, drawn at the same horizon in these widely separated areas. 

It is not so easy to define the upper limits of the Viséan, for the 
Avonian coral and brachiopod fauna persisted longer in some districts 
than others, but over wide areas it gave place, as a result of physiographic 
changes, to a new fauna, chiefly cephalopods and lamellibranchs, which 
persist to the summit of the Lower Carboniferous. Itisto Dr. Wheelton 
Hind we owe the demonstration that this fauna which characterizes the 
Lower Culm is the same as that of his Pendleside Series. Viséan 
cannot be made to include this Culm or Pendleside fauna, which can 
be seen in Derbyshire, Yorkshire, and Lancashire to succeed it. 


Level of the Plant break. 


Upper 
Carboni- 
ferous 


Upper} Upper Yoredale Coral Fauna. 
a Yoredalian 
2 Lower| Entrance of Lower Culm or Pendleside fauna 
& iz (Posidonomya Becheri). 
3 <— 
o =! 
ce Ae ee 
Ss S | Viséan 
i =< Entrance of C-S fauna (Caninia patula, Clisio- 
BS phyllum Ingletonense). 
So 
e Tournaisian 


The difficulty, however, has been to determine the relationship 
between the Yoredale rocks of the typical Yoredale district and the 
Pendleside Series. Reasons have been given” for correlating the 
Posidonomya Bechert beds of the Pendleside Series with the Lower 
Yoredales, and it might be further pointed out that the coral fauna of 
the Upper Yoredale limestones is an appreciable advance on the D, of 
South Wales. Perhaps even more important is the fact that at the 


1 Arthur Vaughan, Brit. Assoc. Reports, Carboniferous Fauna, 1910. 
2 Hvidence for this will be given in the Naturalist, January, 1911, p. 9. 


564 Reviews—Dr. Andrews’ Marine Reptiles, Ozford Clay. 


top of the Viséan there occurs a well-marked Cyathaxonia phase 
which is generally succeeded by the Posidonomya Becheri beds. In 
the typical Yoredale area the same succession has been observed at 
the base of the Yoredales. If the equivalence of the Lower Culm, 
Pendleside, and Yoredale Series be admitted, then a tripartite division 
of the Avonian is necessary, and for this upper division the work of 
Phillips in having pointed out the importance of the Yoredales as 
a distinct division of the Lower Carboniferous should be recognized, 
and the term Yoredalian employed in our proposed classification, shown 
on p. 663. 

It is obvious that with any classification there will be local 
difficulties. It is known that in some places the normal D, conditions 
persisted into Lower Yoredale time, or that it was replaced by 
a development of the ‘ knoll’ limestones. In other areas the 
Cyathaxonia phase is found intercalated with the Postdonomya Becheri 
beds. These difficulties are but local and do not affect the general 
applicability of the proposed classification. 


REVIEWS. 
——_@——_ 


I.—A Descrterive Caratocus or THE Marine Reprines oF THE 
Oxrorp CLAY, BASED on THE Lenps CoLtucrion in THE BritisH 
Museum (Narvurat History), Lonpow. Part I. By Carts 
Wittiam Anprews, D.Sc., F.R.S. 4to; pp. xxiii and 205, with 
frontispiece, 10 plates, and 94 text-figures. Printed by order of 
the Trustees of the British Museum, London, 1910. Price £1 5s. 
OR some years past visitors to the Natural History Branch of the 

British Museum at South Kensington, who have passed through 
the gallery devoted to fossil reptiles, cannot have failed to be 
attracted by certain specimens of Plesiosaurians which, on account 
of their perfect condition and the method of mounting, appear more 
like modern skeletons than the remains of ancient fossil creatures. 

These specimens, it is well known, form part of the famous Leeds 

Collection of fossils from the Oxford Clay of Fletton, near Peterborough. 

It was Dr. Henry Woodward, when Keeper of the Department, who 

first interested himself to obtain these remarkable specimens for the 

British Museum; and his successor, Dr. A. Smith Woodward, has 

been no less assiduous in securing this unique collection. 

It is now several years since the first of the skeletons was placed 
on view in the Museum cases, and it had been mounted most skilfully- 
and with great patience by the late Mr. C. Barlow. Several other 
examples have been added more recently, most skilfully set up by his 
son, Mr. F. O. Barlow, the present formatore. A careful examination 
of these specimens, even by those who are not specially interested 
in fossil reptiles, will prove of no little interest, especially if one 
bears in mind the amount of time, attention, and skill expended in 
bringing them into their present satisfactory condition. 

The greater number of the bones were obtained by Mr. Alf. N. 
Leeds, of Eyebury, Peterborough, during the last twenty years, 
but the collecting was begun much earlier by his brother, Mr. Chas. 
HE. Leeds. Mr. Leeds, living near the Oxford Clay pits at Fletton 


Reviews—Dr. Andrews’ Marine Reptiles, Oxford Clay. 565 


and other localities near by, had unusual facilities for obtaining the 
fossils which were unearthed, and lost no opportunity of rescuing 
them; the greatest care being taken by him to keep the various 
parts of each individual together and separate from others. The 
bones were numbered and packed in separate parcels, so that in 
the end it has been possible to bring together the almost complete 
skeletons of a number of these animals. Frequently the bones when 
found were broken in many pieces, and these were reunited by 
Mr. Leeds with the greatest skill and patience. Subsequently, when 
the specimens came into the possession of the British Museum, they 
were mounted with no little ability by the formatore in the Geological 
Department, and now several of them are to be seen in the Museum 
eases. ‘Those of us who have examined these wonderfully recon- 
structed skeletons have long been hoping for some account of them, 
and at length we have the satisfaction of welcoming the volume 
which has been published by order of the Trustees of the British 
Museum, and proves to be a memoir worthy of the institution 
from which it issues. The work is entitled 4 Descriptive Catalogue 
of the Marine Reptiles of the Oxford Clay, but although this title 
may be correct it conveys but little idea of the careful and detailed 
labour which has been bestowed upon the volume by Dr. Andrews. 
It is an elaborate memoir, and will in future be the necessary work 
of reference for the Oxford Clay reptiles of which it treats. 

Dr. Andrews, in his Introduction, gives an interesting general 
account of the collection, and says the perfection of some of the 
specimens is such that ‘‘it has been possible to mount the bones 
in their natural relations as easily as if they had been obtained by 
the maceration of a fresh carecass’’. ‘‘ A notable instance of this is 
the fine skeleton of Cryptocleidus oxoniensts which is figured on the 
Frontispiece,’’ reproduced from a photograph. Skulls, it seems, 
have rarely been found in anything lke a perfect condition, and 
frequently some part of a skeleton, such as a limb, is wanting in 
an otherwise perfect specimen; from these and similar facts it is 
argued that many of the bodies must have been dismembered while 
the bones were still united by the softer tissues. A short account 
is given of the geological horizon that has yielded this collection 
of fossils, which is said to be the Lower Oxford Clay of English 
geologists, characterized by numerous examples of the ‘Ornatus’ 
group of Ammonites. 

The present volume is only the first part of the entire work, and 
is restricted to the description of the Ichthyosaurian and Plesiosaurian 
remains; while Part II, we are promised, will deal with the Pliosaurs 
and Crocodiles. 

The Ichthyosaurian specimens are all referred to one genus and one 
species, Ophthalmosaurus vcenicus ; and it is pleasing to find that these 
names, proposed by: the late Professor H. G. Seeley (thirty-six years 
ago), can be retained for them: his keen insight into the details of 
reptilian osteology enabled him to realize the importance of characters 
which are still used for their generic distinction. Although only one 
Ichthyosaurian species is recognized by Dr. Andrews in the present 
work, he appreciates the large amount of variation to be seen in 


566 Reviews—Dr. Andrews’ Marine Reptiles, Oxford Clay. 


different skeletons; due to some extent, no doubt, to age and various 
stages of ossification, as well as to conditions of fossilization: and 
he makes the pertinent observation that ‘‘ If only a few skeletons had 
been preserved several forms would probably have been recognized 
and named’’. But with so large a series before him ‘‘it has been 
found impossible to distinguish more than a single species”. Few 
geologists will be inclined to find fault with this specific restriction, 
although ‘‘future investigations may render possible the diagnosis 
of others ”’. 

The restoration of the cranium of Ophthalmosaurus has been an 
exceedingly difficult matter, seeing that it was largely cartilaginous, 
and consequently the bones show few or no sutures, or surfaces of 
actual contact; indeed, but for the fact that in this collection of 
fossils only one Ichthyosaurian genus seems to be represented, it 
would have been a wellnigh hopeless task. Numerous specimens, 
illustrating all parts of the skeleton, are described in detail, and after 
a short account of the species there follows a catalogue of the very 
numerous specimens preserved in the Museum. 

The Plesiosaurs all belong to the one family of the Elasmosauride, 
characterized chiefly by the scapule meeting in a median symphysis 
which is continuous with the symphysis of the coracoids: and the 
scapule grow inwards (in front) below the clavicles and interclavicles. 
The clavicular elements become more or less reduced, and it is the 
variations in this reduction which supply some of the chief characters 
for the distinction of different genera. Four genera of Elasmosauride 
are recognized: MMurenosaurus, with three species; Picrocleidus, with 
two forms, only one of which is specifically named; Ziiclecdus and 
Cryptoclerdus, each with one species. Of these four genera two, 
Murenosaurus and Cryptocleidus, were so named by Professor Seeley, 
the first in 1874 and the other in 1892; while Prcrocleidus and 
Tricleidus are genera established by Dr. Andrews quite recently. 

The most perfect specimen in this collection is, perhaps, the 
Cryptocleidus oxoniensis, already mentioned as being mounted in the 
Museum and figured as the frontispiece; and this species has an 
additional interest inasmuch as it was first described by Professor 
Phillips in 1871 in his Geology of Oxford. 

Each genus is separately discussed by the author, and numerous 
specimens described in detail: the various parts of the skeleton, 
skull, vertebral column, pectoral and pelvic girdles, and limbs being 
treated separately and illustrated by plates and text-figures. Following 
the description of each genus is a brief account of the species referred 
to it, and a catalogue of the specimens preserved in the Museum. 

The volume is liberally illustrated, for besides the frontispiece there 
are ten lithographic plates and ninety-four figures in the text. Eight 
of these plates have been drawn by Miss G. M. Woodward with her 
usual care and artistic finish, and two are the work of Mr. A. H. Searle | 
and are equally worthy of commendation. The text-figures leave 
nothing to be desired in the way of clearness ; but, like so many text- 
figures in present-day publications, they are far from adding to the 
beauty of the page; many of them, too, are far larger than is 
necessary to show the required details; and might almost be called 


Reviews—H. B. Woodward’s Geology of the London District. 567 


rough diagrams rather than figures which, while giving the necessary 
illustration, embellish the page. Modern process-blocks are far from 
having attained to the perfection which is to be found in many of the 
old-time woodcuts. 

It will be eminently pleasing to paleontologists and, indeed, to all 
scientific workers to know that the Trustees of the British Museum 
have added this Descriptive Catalogue of the Oxford Olay Reptiles to 
the long list of their admirable publications. We await with some 
impatience the publication of the second volume; and in the mean- 
time congratulate Dr. Andrews on this most successful completion of 
the first part of his valuable work. 

BM eNe 


II.—Mewnorrs oF tHE GronoeicaL Survey, Eneranp AnD WALES. 


THE Gxrotocy or tHE Lonpon Disrricr (being the area included in 
Sheets 1-4 of the special Map of London). By Horace B. 
Woopwarp, F.R.S. London: printed for H.M. Stationery Office, 
and sold by EH. Stanford, Long Acre, and T. Fisher Unwin, 
Adelphi Terrace. 8vo; pp. viii and 142, with a small contour- 
map of the London District. Price 1s. Sheets 1-4, price 1s. 6d. 
per sheet. 1909: 

f{\HIS memoir was issued early in the present year (1910), and is 

intended to carry on The Guide to the Geology of London and the 

Neighbourhood, prepared by that indefatigable geologist Mr. Whitaker 

and published in 1875. That work reached its s¢zth edition in 1901, 

and is now out of print. The four-sheet map now issued, printed in 

colours (which is less expensive and slightly smaller than that published 
in 19038), is largely founded on Mr. Whitaker’s work, and also on 
subsequent work by Horace B. Woodward and other members of the 

Survey. 

‘No one,” says Dr. J. J. H. Teall, ‘‘can write on the geology of 
the neighbourhood of London without being indebted to the work 
of the late Sir J. Prestwich and of Mr. Whitaker. In the early memoir 
on The Geology of the London Basin, and in the two volumes on 
The Geology of London, Mr. Whitaker not only recorded all the facts 
gathered during the progress of the Geological Survey, but dealt fully 
with the observations of other geologists, adding his own criticisms 
on divergent views ... Though no effort has been spared by 
Mr. [ Horace] Woodward to acknowledge the sources of information, 
it has proved to be impossible to do justice to the voluminous literatur 
within the limits of so small a memoir.” 

The four new sheets which the memoir is intended to explain and 
describe have each an zmsede coloured area of 184 inches by 123 inches, 
with explanation of colours and formations on their outer margin, 
the scale given being 1 inch to 1 statute mile, their united surfaces 
covering an area of 363 x 244 miles. They are called ‘‘ Drift Maps”, 
but they really show the extent of the strata or geological formations 
which occur immediately beneath the soil. As examples we may 
mention the Thames Valley Gravel, the Bagshot Sand, the Thames 
Valley Brickearth, the London Clay, the Boulder-clay, the Chalk, and 
the Peat which occurs in the Alluvium of the Marshlands. 


568 Reviews—H. B. Woodward’s Geology of the London District. 


“The Chalk forms the foundation of the entire area. It is followed 
by the Eocene Series, which is represented in and around London by 
the Thanet Sand and higher divisions up to the Bracklesham and 
Barton Beds. This series occupies a shallow trough formed by the 
uplift and bending of the great mass of Chalk so as to constitute what 
is known as the London Basin; and thus it covers the Chalk from 
Dartford and Croydon on the south-east to Watford and Rickmansworth 
on the north-west .. . It is with the Subsoil, not the Soil, except 
in the case of artificial accumulations of Made Ground, that the 
Architect, Physician, and the House-Hunter are concerned.” (p. 2.) 

‘The story of London is usually reckoned to commence less than 
nineteen hundred years ago, when the Britons, who had established 
a kind of fortified settlement on the rising ground now dominated by 
St. Paul’s Cathedral, were displaced by the Romans (4.p. 43)... 
The Holbourne or Fleet Stream occupied the valley to the west, and 
the lower part of its course was tidal; while the Wallbrook entered 
the Thames on the east, above the reach known as ‘ The Pool’.” (p. 3.) 

Although on a very reduced scale, the small contour-map which 
accompanies the memoir gives an exceeding clear idea of the hills, 
valleys, and streams of the London area, from Rickmansworth in the 
west to Brentwood in the east, and from Barnet and Enfield in the 
north to Ewell and Shoreham in the south. An ideal valley, well 
suited to the needs of its vast population, fed by innumerable streams 
of sweet water rising from the high grounds north and south, and 
which, but for the insanitary habits of its mediaeval and later 
inhabitants, might, as my old friend Dr. G. V. Poore} pointed out, 
have remained in sight the joy and glory of London, but, through 
constant pollution, they had compulsorily to be put underground, 
where they still flow in our sewers, serving as our unseen benefactors 
and sweetening the evils of life. 

The history of underground London, geologically speaking, takes us 
far below the greatest depths of sewers or tube-railways, but is only 
known through the all too few experimental artesian borings which 
have been made in various parts of the area of greater London, 
commencing with the historic Kentish Town boring reported upon by 
Professor Prestwich* and later on by Mr. Godwin-Austen,? which 
reached a depth of 1,802 feet. 1883 feet of red and mottled clays, 
sands, sandstone, and conglomerates were proved, but their age is 
uncertain, although most probably Paleozoic. Undoubted Devonian 
fossils were obtained from a boring at Meux’s Brewery, Tottenham 
Court Road, 1,066 feet from the surface. At Richmond Professor 
Judd records that fragments of anthracite mingled with Coal-measure 
sandstone and other Paleozoic rocks were found in considerable 
abundance, so that we may conclude that the coal under London has 
really been found, though not in situ.4 

1 London Ancient and Modern, from a Sanitary and Medical Point of View, by 
G. V. Poore, M.D., F.R.C.P. (Cassell & Co., 1889), 8vo, pp. 6 and 128. 

2 Q.J.G.8., 1856, vol. xii, pp. 6-14 (1855). 

3 Q.J.G.8., 1856, pp. 838-73; also Proc. Roy. Inst., vol.ii, p. 511. Mr. Godwin- 
Austen wrote on the boring at Meux’s Brewery, Guou. Mac., Dec. II, Vol. IV, 
pp. 474-5, 1877. 

+ Q.J.G.8., vol. xl, p. 760, 1884. 


Reviews—H. B. Woodwara’s Geology of the London District. 569 


A boring by the New River Company at Turnford, near Cheshunt, 
reached Silurian strata at 796 feet. : 

At Crossness 52 feet of hard red and grey micaceons and quartzose 
rocks, red shales, and grey sandstones were met with (suggestive of 
Devonian rocks), but no fossils are recorded. 

At Streatham boring 138 feet of reddish and purplish sandstones of 
New Red (or possibly Devonian?) age were passed through. Some 
of these doubtful red rocks may prove to be stained Carboniferous 
strata, as suggested by Mr. Whitaker.’ These borings have also 
yielded rocks of Great Oolite age. 

“Thus we find at a depth of 1,000 feet and more under London 
strata the representatives of which come to the surface about 100 miles 
distant on the west. There is evidence, however, that the Jurassic 
strata occur under London in the form of a denuded anticline, as on 
the west and north-west the Kimeridge Clay, Portland and Purbeck 
Beds, are the nearest of the exposed Jurassic rocks; on the east, 
beneath Chatham, the Oxford Clay has been reached, and on the 
south-east higher Jurassic divisions occur. No representatives of 
the series are present below Crossness.”’ (p. 8.) ; 

In short we find that the synclinal fold of Cretaceous rocks in which 
the London Tertiary basin lies, rests upon a denuded anticline of older 
Secondary rocks whose base consists of Paleeozoics of Carboniferous 
and in part of Devonian and even Silurian strata. 

Fifteen sections in the text and a contour-map, with a general 
geological section showing the relations of the rocks along a line 
across the London Basin from Watford to near Shoreham, serve 
admirably to illustrate the Cretaceous and Tertiary Series and their 
distribution at the surface over the London district as set forth by 
the author in Chapters III and IV, whilst the faults and disturbances 
to which these formations have been subjected are described in 
Chapter V. The surface configuration marked by the Pliocene and 
older Drifts are considered in Chapter VI, and the Pleistocene and 
newer Plateau Drifts and Glacial Deposits in Chapter VII. More 
attention is given to the contours which affect the water-partings and 
the river-courses, in illustration of which a useful little map by 
Mr. A. Strahan is introduced on p. 62 to show the Thames and its 
affluents from the Cotteswolds to the Nore. 

The Plateau and Valley Gravels and the Terraces along the river- 
course have furnished a very interesting chapter in the history of 
early Man in the Thames Basin (Chapter VIII). We obtain exact 
evidence of Man in the Paleolithic age, by his various types of flint 
implements (see figs. 18-16, pp. 79-80), from the high and low 
level gravels corresponding in relative antiquity with those of 
La Madélaine, Solutré, Le Moustier, St. Acheul, and from Chelles 
(Seine-et-Marne) in the French caves and gravel deposits. Moreover, 
their occurrence has been observed for more than 200 years, ‘‘a British 
weapon found with Elephant’s tooth”’ having been dug up in Gray’s 
Inn Lane about 1690 and since preserved in the British Museum 
(p. 79). Added to the flint implements left by early Man, as evidence 


| Address to the Geological Society, Q.J.G.S., vol. lvi, p. 83, 1900. 


570 Reviews—F. P. Mennell’s Petrology. 


of his residence in the Thames Valley in prehistoric times, we are also 
furnished with a long list of the animals (thirty-five are recorded) 
which he saw and hunted (pp. 76-7), most of which are now extinct 
or are no longer living in Britain, but which were then indigenous to 
the London district. In Chapter 1X the Holocene or Recent deposits 
are described, and much interesting information is given as to the 
wild Mammalia which had their home around British London and in 
Roman and later times. Some twenty-four species are recorded on 
pp. 99-100. 

Water supply is not neglected (see Chapter X), and some yery 
interesting records are given of old sources of supply. The Metro- 
politan Water Board have now to provide for a population of nearly 
seven millions of inhabitants at the rate of 30 gallons, or a little 
more, per head daily, the daily amount of water required being about 
225 millions of gallons (p. 115). 

The author in his conclusion reminds us that ‘‘ the present diversified 
features are the result of a great series of changes of earth-movements, 
erosion, and deposition, accompanied by varying conditions of scene, 
climate, and life; and how the aspect of the country has been modified 
in later times by the agency of Man. . . . We have further shown 
how the geological structure has influenced the water supply, and 
how the different strata have yielded materials of economic value, 
conducive to the well-being of the community”’ (p. 132). 

We congratulate the author (Mr. Horace B. Woodward), who has 
followed in the steps of his predecessor (Mr. W. Whitaker) and 
' has produced an excellent and useful memoir upon the area of the 
greatest and most populous city on the globe. The maps specially 
deserve commendation, and the price of the maps and the memoir are 
both extremely moderate. 


III.—Awn Inrropucrion to Prrrotoey. By F. P. Mennentt, F.G.S8. 
8vo. London: Gerrards, Ltd. 


fYXHIS little volume of some 200 pages presents an attractive 

appearance, and in its internal arrangement gives evidence 
of much thought and an acute appreciation of some of the difficulties 
which beset an elementary student of petrology. The plan of the 
work is distinctly good, but unfortunately the chapters do not fulfil 
the promise of their headings. The first half of the book, which 
deals with general principles and rock minerals, is the weaker portion, 
and it is evident that the second half, which treats of rocks and rock 
structures, was that part of the work with which the author was 
most at his ease. 

It is to be regretted that the earlier portion does not fulfil the 
purpose that the author intended for it; had it done so, the volume 
as a whole would have formed a self-contained and most useful guide 
to the microscopical study of rock-forming minerals and rocks. 

In reading the earlier chapters it is impossible to pass without 
comment such statements as the following, which, if not quite 
incorrect, must at any rate lead to much confusion. On p. 25 he 
says: ‘‘ Every mineral refracts light to a certain extent, that is to say, 


Reviews—New Geological Maps. 571 


makes light deviate from a rectilinear path in passing through it. 
Now on the undulatory theory light is composed of vibrations of the 
ether in all possible directions. When, however, it passes through 
a crystal belonging to any other than the regular system all the 
vibrations are made to take one or other of two definite directions at 
right angles to each other and to the direction of propagation. The 
light is then said to be polarised.’?’ There is also much confusion in 
the use of the terms ‘refractive index’ and ‘indices’. Again, on 
p. 31 he says: ‘‘ The mica gives a typical biaxial figure showing two 
dark hyperbole (brushes), which unite four times during a rotation 
(at the extinction positions) to form a cross of which one arm is 
broader than the other. The thin arm joins the optic axes. The 
broad arm is called the bisectrix, in the case of mica the acute 
bisectrix as it bisects the acute angle between the optic axes.” On 
the following page, speaking of the optical sign of minerals, he 
remarks: ‘‘ Some minerals have their interference tints heightened 
when covered with a quartz wedge having its long axis in the same 
direction as their own, while others have them lowered. In the first 
case the sign of the double refraction is said to be posetive, in the 
latter it is negative.’ We are left to guess, however, what 
constitutes the ‘long axis’ of either the crystal or the quartz wedge. 
The whole of the introductory portion dealing with the crystallineform . 
and optical properties of minerals is put into twenty pages, and is 
almost valueless to any serious petrological student. Chapters VII-XI 
deal with the rock-forming minerals, and these constitute a useful 
portion of the book. However, it would have been better if the 
minerals had been arranged according to their crystalline system or 
their optical behaviour rather than their chemical composition. 
Their descriptions are often somewhat unscientific, and occasionally 
there are insufficient data for the identification of a certain species. 
It is to be remarked that such valuable mensurate constants as the bi- 
refringence in anisotropic media are disregarded. Chapters XII-XXI 
refer to igneous and sedimentary rocks, and the processes and products 
of metamorphism and weathering. The description of the various 
simple rock types is by far the best portion of the work, but it suffers 
from incompleteness, and there is occasionally a lack of definition of 
tock names and structures. Many of the illustrations are admirable, 
especially those which are reproduced from line-drawings, but some 
of the photomicrographs are too smudgy and out of focus to be worth 
the space they occupy. 
Fe Hee 


TV.—Somr New Geotocicat Maps. 


1. Gxotocican Map or Eeypr.—We have received from the Survey 
Department, Cairo, a geological map of the country issued 1910, in 
six sheets, on the scale of 1 : 1,000,000, on which the various 
formations are very clearly shown in colour-prints. No record, 
however, appears of the names of the geologists who are responsible 
for the field-work. The area extends from the Gulf of Salum and 
Alexandria to Port Said on the north, and from Wadi Halfa to Ras 
Hadarba on the Red Sea coast on the south. The southern part of 


572 Reports and Proceedings—Geological Society of London. 


the Sinai Peninsula is also coloured geologically. Notes of mines 
and quarries are printed on the map, and the ‘“‘ Gravel Ridges of 
Quartz and Chert Pebbles with Silicified Trees” are indicated in the 
Oligocene tract west of Cairo. The famous ‘‘ Petrified Forest” that 
occurs to the east-south-east of Cairo occupies a comparatively 
small area and is not marked. Some account of it was given by 
Mr. Carruthers in the Grorocicat Macazine for July, 1870 (p. 306). 

Another geological map of Egypt, in one sheet, scale 1 : 2,000,000, 
has'also been published by the Survey Department. 

2. Oxrorp Watt Maps.—A series of wall-maps designed to assist 
teachers of Geography is in course of preparation and publication at 
the Clarendon Press, Oxford, under the editorship of Professor A. J. 
Herbertson. The maps are not simply reproductions of existing 
works, but have been specially prepared with the aid of experts, and 
drawn by Mr. B. V. Darbishire, M.A. Most of the maps are to be 
printed without names of places, etc., as these obscure the main 
features. Such is the case with the specimen before us, ‘‘ The British 
Isles, Geology.” The scale is 1 : 1,000,000 or about 16 miles to 
1 inch. Squares printed in black, alongside the scale, show 
respectively areas of 250 square miles and 100 square kilometres. 
The geological groups that are indicated by colour on the map are 
Igneous, Archzan, Cambro-Silurian, Devonian—Carboniferous, Permo- 
Triassic, Jurassic, Cretaceous, and Tertiary. Coal-measures are 
printed in black, and the other Carboniferous strata are distinguished 
from Devonian by cross-ruling. Magnesian Limestone, Oolite Lime- 
stone, and Chalk are indicated in a general way by cross-ruling. The 
colour-printing is clear, and although there are some slight differences 
in shade between the northern and southern halves of the map (which 
have been separately printed), they are hardly noticeable at a distance. 
The map, which includes the adjacent portions of France and the 
Channel Islands, should be a very useful diagram to a teacher versed 
in geology, especially if provided also with a map of the physical 
features and a series of geological sections. The price of the 
geological map is 7s. unmounted, 8s. 6d. mounted on cloth to fold, 
and 10s. 6d. on rollers. 


RmEPOnRLTS AIND LROCHA DINGS: 


Grotogicat Socitety or Lonpon. 


November 9, 1910.—Professor W. W. Watts, Sc.D., M.Sc., F.B.S., 
President, in the Chair. 

The following communications were read :— 

1. ‘‘ The Rhetic and Contiguous Deposits of West, Mid, and Part 
of East Somerset.’? By Linsdall Richardson, F.R.S.K., F.L.S., F.G.S. 

This paper contains a detailed account of the Rhetic strata of 
Somerset, with the exception of a small area bordering upon Bristol. 
The magnificent sections at Blue Anchor and Lilstock are described 
in detail, and correlated with those on the opposite Glamorgan coast. 
The record by Professor Boyd Dawkins of characteristic Rheetic 
mollusca in the top portion (uppermost 14 feet or so) of the Grey 
Marls is confirmed, and the contention for their recognition as Rheetic 


Reports and Proceedings—Geological Society of London. 573 


is fully substantiated. The deposit between the top of the fossiliferous 
Grey Marls or ‘Sully Beds’ and the main Bone-bed at Blue Anchor 
measures 22 feet, and teems with interesting Rheetic fossils, such as 
Pteromya crowcombeia, Moore. The beds above the Bone-bed agree 
very well with those occupying the same stratigraphical position in 
Glamorgan, and include the ‘ Upper Rhetic’, the equivalent of the 
White Lias proper, and the ‘ Watchet Beds’. The now obscured 
magnificent sections, that were temporarily to be seen in the railway- 
cuttings at Langport and Charlton Mackrell, briefly noticed by 
Mr. H. B. Woodward, are described in detail (the records being made 
in company with Mr. E. T. Paris, F.C.S.). Here huge boulder-like 
masses of rock were noted at the top of the Black Shales, and the 
White Lias proper, with a well-marked Coral Bed, totalled 25 feet in 
thickness. ‘The classic sections of Snake Lane, Dunball (Puriton), 
Sparkford Hill (Queen Camel), Shepton Mallet, and Milton (Wells), 
have been re-investigated and brought into line; and the interesting 
thin Rheetic deposits in Vallis Vale, at Upper Vobster, and sections in © 
the Radstock district, and on the Nempnett and neighbouring outliers, 
are described. In addition to the record of many new or imperfectly 
known sections, this investigation has also shown that the MWicrolestes 
Marls are equivalent to the Sully Beds: that the Wedmore Stone 
occurs well below the Bone-bed; that Moore’s ‘ Flinty Bed’ at Beer 
Crowecombe is probably on the horizon of the Plewrophorus Bed 
(No. 18); that the Upper Rheetic (generally with Cotham Marble or 
its equivalent) is as persistent as usual, if not quite so thick; that 
the White Lias proper is of restricted geographical extent; and that 
on the Bristol Channel littoral are marls, ‘ Watchet Beds,’ above the 
White Lias. Around Queen Camel, Moore’s ‘ Insect and Crustacean 
Beds’ appear to come in at an horizon which lies between the Watchet 
Beds and the Ostrea Limestone. 

The following classification of the Rheetic Series is suggested, and 
the succession of maxima of the characteristic fossils is given in the 
paper :— 

Thicknesses in 


Lras. HErTANGIAN. Ostrea Beds, etc. England. 
( I. Watchet Beds (‘ Marly Beds ) : 
{ of the White lias’) 0 #0. 7 #4. Zan. 
SOMERSETIAN He es Jade (Wie a7 \ 0 to 25 ft. 
RuztTIc + [a Westbury Beds (‘ Upper \ 2 ft. Vin. to 19 ft 
Rheetic ’) APG ; ; 
| ( IV. Lilstock Beds (Black Shales) 1 to (?) 47 ft. 
| RH=TIAN V. Sully Beds (Fossiliferous 
l | Grey Marls) | 0 to 144. 


oan { ee { Perera ane Grey Marls . . 111 ft. (max.). 

The sudden lithic and faunal changes in the contiguous divisions 
are held to be the expression of oscillatory movements and interrupted 
sequential deposition. The fauna of the Rhetian is decidedly Swabian 
in facies, and the general conclusion to be derived from the study of 
the beds is in entire agreement with Suess’s view, that while the 
dominant movement was one of subsidence and not local but extended, 
it was, nevertheless, ‘‘ oscillatory and slow.” 


O74 Correspondence—A. R. Horwood. 


2. ‘‘ Jurassic Plants from the Marske Quarry.”’ By the Rey. George 
John Lane, F.G.S. 

The Marske Quarry is situated on the northern side of the Upleatham 
outlier in the Cleveland district of Yorkshire. It is about 500 feet 
above sea-level. In the quarry several varieties of rock are exposed, 
namely shales, small coal-seams, sandstones, and a ferruginous bed. 
The beds are of Lower Oolite age, and belong to the Lower Estuarine 
Series. As the Millepore Bed is absent in the district, the Lower 
Estuarines and the Middle Estuarines may be one continuous deposit. 
From this quarry Dictyozamites was recorded for the first time in 
England, its occurrence being made the subject of a paper presented 
by Professor Seward to the Geological Society in 1903. The writer 
has obtained nearly forty species from the quarry, among which are 
many characteristic Wealden plants. This discovery is most interesting, 
especially when one considers the vast interval of time that elapsed — 
between the horizons of the Inferior Oolite and the Wealden. 


CORRESPON DEN CHE. 


THE ORIGIN OF THE BRITISH TRIAS. 

Sir,—In reply to your correspondent Mr. W. B. Wright,! of the 
Scottish Geological Survey, who has doubtless heard much of the 
Desert theory from his former colleague, Mr. T. O. Bosworth (who has 
so ably described the evidences of desert conditions in Leicestershire), 
Mr. Wright must know that it is unusual to criticize an abstract ? 
before the full text of the paper is printed. I shall therefore be 
as brief in my reply as I was in the abstract, only quoting the 
numbered passages from Mr. Wright’s letter. I may reply— 

(3) Ido not speak of a general absence of delta-bedding, for see (9). 
It does occur. Professor Bonney is cited by me as proving the delta 
origin of the Bunter, and I do not propose here to add one iota to his 
evidence. It is quite clear enough, and the Survey Library contains 
the papers in which Professor Bonney published his proofs. The 
dactyloid form is just a further point of analogy, and the extension 
of the Trias delta-head is suggested by evidence from deep borings 
(as to which let Mr. Wright ask Mr. Whitaker, who will also give 
him ‘all the bibliographical assistance he needs, as he kindly did 
for me) in the East and South-East of England, chiefly made in 
connexion with explorations for coal. 

(9) It would be equally as fruitless as trying to find the river-bed 
of the Triassic delta (or its tributaries) to expect to show beds in 
the act of tilting through an angle of 45°; but it is an axiom of 
modern physical geography (which I merely extend to the past) that 
beds when subsiding do tend, when so elevated, to become horizontal 
finally. The discontinuity of delta-bedding, laterally and vertically, 
seen so clearly in Staffordshire and Notts., is an ocular demonstration 
of what has happened in the past; but no more is to be expected. 
The characteristic overlapping, of which Mr. Wright must have 

1 See Grou. Mac. for November, 1910, p. 526. 

* See ‘‘ Origin of the British Trias’’, by A. R. Horwood (Abstract of paper 
read at the British Association, Sheffield, September, 1910): Gzox. Maa., October, 
1910, p. 460. 


Obituary—John Roche Dakyns, M.A. 579 


seen something in Notts., gave rise in early Survey days to the 
interpretation of certain sections of strata so juxtaposed as faulted 
beds. Viewed as delta-bediled deposits the faults disappear, and such 
instances can perfectly well be illustrated on a map just as the 
discontinuous bedding. 

(16) Rocks polished by wind-action occur at various points at 
Mount Sorrel, Croft, and elsewhere. These older pre-Triassic rocks are 
at practically the same level as O.D., and the Trias was laid down just 
as we now find it, with a slight dip, allowing for subsidence. It is 
merely a petitioprincipr to say casesfor observing wind-polishing are very 
exceptional. But it is very damaging evidence for the desert theory 
to show that this action occurs only where red marl abuts against 
older rocks and along a single horizontal line. This illustrates the 
local (littoral or marginal) character of desert action in Triassic times. 

(20) A reference to Professor Hull’s Survey memoirs and Professor 
Bonney’s papers will give Mr. Wright the information he desires. 

(21) The nature of the heavy minerals of the Bunter, Keuper, and 
the Nile indicates that they have a common character and in their 
several areas a common origin to a great extent. It is known that 
the Nile delta deposits are mechanically altered, owing to their having 
been, in part, derived from a contiguous desert. In the Nile the 
water is free from those chemical agents which ordinary river- or rain- 
water contain, so that chemical action is absent. In the Trias river 
and rain have acted in such a way during the past that the marls 
of the Upper Keuper exhibit their effect. This point is another 
corroborative of the aqueous origin and, together with other indications, 
of the delta origin of the Trias. A. R. Horwoop. 


Leicester Museum. 
November 14, 1910. 


(QSL OIA Se Soe 


JOHN ROCHE DAKYNS, M.A. 


Born January 31, 1836. Diep SEPTEMBER 27, 1910. 


J. R. Daxyns, the eldest son of Dr. Thomas Henry Dakyns, was 
born in the island of St. Vincent, West Indies. In 1845 the family 
removed to England, and settled at Rugby, where J. R. Dakyns 
received his early education. In 1855 he proceeded to Trinity 
College, Cambridge; four years later he gained the position of 
twenty-seventh Wrangler in the Mathematical Tripos; and during the 
next two years he was engaged in teaching. Mathematics was 
a subject at all times of great interest to him, but Physical Geography 
likewise had its attractions. Hills and mountains exerted a magnetic 
influence on him, and the contemplation of these great features 
probably led him to the study of Geology. Eventually he found 
a congenial outdoor profession on the staff of the Geological Survey. 
He joined as an Assistant Geologist on January 16, 1862, and was 
promoted to the rank of Geologist on January 1, 1868. 

In the course of his field-work he was principally occupied in the 
West Riding of Yorkshire and bordering tracts of Derbyshire, 
Lancashire, and Westmorland, and for a few years in the East 


576 Obituary—John Roche Dakyns, M.A. 


Riding. The results of his labours are given on the Geological 
Survey maps, and (as part author) in the memoirs on North 
Derbyshire (1869), the Yorkshire Coal-field (1869 and 1878), Leeds 
and Tadcaster (1870), Dewsbury, Huddersfield, and Halifax (1871), 
the Burnley Coal-field (1875), Bradford and Skipton (1879), 
Bridlington Bay (1885), York and Hull (1886), Driffield (1886), 
Kendal and Sedbergh (2nd ed., 1888), Ingleborough (1890), Maller- 
stang (1891), and Appleby (1897). On the mountains and uplands 
of the Lower Carboniferous rocks Dakyns was in his element, 
whereas when surveying for a time in the lowlands of Holderness 
he was by no means so buoyant in spirits. On the completion of the 
1 inch geological map of England and Wales in 1884 he was 
transferred to the Scottish branch of the Geological Survey, and was 
engaged for ten years in mapping parts of the Forest of Athole, the 
country westwards to the borders of Argyllshire, and that around 
Loch Lomond in the counties of Stirling and Dumbarton. So far as 
mountain scenery was concerned Dakyns was in a kind of paradise, but 
the uncertainties of the geology sorely taxed him, and he was heard 
on one occasion to remark that hell was paved with Highland schists. 

In conjunction with Dr. Teall he communicated to the Geological 
Society mm 1892 an important paper ‘‘On the Plutonic Rocks of 
Garabal Hill and Meall Breac’’. 

In 1894 Dakyns was transferred to South Wales to take part in the 
re-survey, on the 6 inch scale, of the Coal-field and bordering rocks. 
There he rejoiced in mapping the hilly ground of Old Red Sandstone 
and Lower Carboniferous rocks around Abergavenny, and he con- 
tributed to the memoir on that area, which was published in 1900. 

He retired from the Geological Survey on April 30, 1896, soon 
after attaining the age of 60, and took up his residence at Snowdon 
View, Beddgelert, where he spent a pleasant and happy time 
geologizing in that mountain region. He re-mapped on the 6 inch 
scale the greater part of Snowdon, together with much of the adjacent 
country; and his maps and notes embody important revisions and 
additions to the knowledge of the district. It is much to be desired 
that this work should see the light; and as one of his intimate friends 
is, we understand, about to complete the parts left unfinished, we may 
hope that this will be accomplished before long. ‘Through the results 
of a chill his active life was terminated after a brief illness, in his 
75th year. 

Although he never became a Fellow of the Geological Society, 
Dakyns communicated to that Society in 1872 a paper ‘‘On the 
Glacial: Phenomena of the Yorkshire Uplands”; he was a frequent 
contributor to the GrotogrcaL Magazine, on subjects relating more 
especially to Carboniferous and Igneous rocks, to Glacial Phenomena 
and Cave-deposits, and he was author also of papers published by the 
Yorkshire Geological and Polytechnic Society. Extremely original 
in character, and very widely read, intercourse with him possessed. 
unusual fascinations; moreover, being full of sympathy for all living 
beings, and a staunch friend, he was endeared to all who had the 
privilege of his acquaintance. 


H. B. W. & E.G. 


INDEX. 


CIDASPIS semievoluta, F. R. C. 
=“ Reed, sp. nov., 214. 
JMolian Deposits, 6, 97, 522. 
Africa, West Coast, Foliated and other 
Rocks, 529. 
Agassiz, Alexander, Obituary of, 238. 
Algonkian, Fossils in, Scandinavia, 377. 
Ambulacra in the Holectypoida, 349. 
Ammonites cordatus, Sby., and A. 
excavatus, Sby., 503. 
Amphiboles, Development of, 357. 
Amroth, Glacial Drift near, 279. 
Andrew, A. R., The Dolgelley Gold-belt, 
159, 201, 261. 


Andrews, C. W., Skeleton of Peloneustes 


philarchus, 110; 
Oxford Clay, 564. 

Annelid Burrows, Fossil, 114. 

Anodonta Becklesi, Newton, Wealden, 
Hastings, 525. 

Anthrvacomartus and Promygale, 505. 

Aragonite, Middle Lias, Leicestershire, 
173. 

Arber, E. A. Newell, Fossil Plants, 
Gloucester Coal-tield, 241, 

Archeosigillaria in Westmorland, 78. 

Archeosigillaria Vanuxemi, Horizon of, 

117. 

‘Archimylacris (Etoblattina) Woodwardi, 
Bolton, sp. nov., 147. 

Argyll, Mid, Geology of, 37. 

Armenia, Geology of, 283. 

Arnold- Bemrose, 18h 7 Olivine Nodules 
in Basalt, 1. 

Augen Gneiss and Moine Sediment, Ross- 
shire, 337. 

Australia, West, 89 ; Mammoth Cave in, 
240. 


AGSHOT Beds, 
Kent, 405. 
Ball, J., Origin of Nile Valley and Gulf 
op Suez, file 

Basalt, Olivine Nodules in, 1. 

Basingstoke, Geology of, 82. 

Bather, F. ‘AC, Fossil Annelid Burrows, 
114. 

' Bauerman, H., Obituary of, 46. 

Beadnell, H. J. L., Sand-Dunes of the 
Libyan Desert, 477. 

Bembridge Fossils, Creechbarrow Hill, 
436. 

Beyrichia  (Ceratopsis)  Duftonensis, 
ae R. C. Reed, sp. nov., 217. 
3. (Ctenobolbina ¢ 2) superciliata, F.R. C. 
fae sp. nov., 218. 


DECADE V.—VOL. VII.—NO. XII. 


Marine Reptiles, 


Shooters Hill, 


Beyrichia ( Tetradelia) Turnbulli, F.R.C. 
Reed, sp. nov., 219. 

Blake, W. P., Obituary of, 384. 

Bodmin and St. Austell, Geology of, 84. 

Bolton, H., A Carboniferous Cockroach, 
South Wales, 147. 

Bonney, Professor T, G., Presidential 
Address British Association, 463, 418. 

Bostall Common Drift, 534. 

Bosworth, T. O., Wind Erosion, Mull, 
000. 

Boe R., Geologyand Civil Engineering, 


Brighion Cliff Formation, 290. 

Bristol, Geology of, 92. 

Bristol ’Coal- field, Fossil Flora of, 58. 

ae Association, Presidential Address, 

63, ; Titles of Geological Papers 
aa oh 

British Earthquakes, 315, 410. 

British Fossils, 128. 

British Guiana, ‘ Laterite’ 
5653. 

British Museum (Natural Wistory), 
Catalogue of Bryozoa, 321; Catalogue 
of Books i in, 475; Catalogue of Marine 

Reptiles, 564. 

British ‘Trias, 
574, 

Broeck, E. van den, and others, Caves ot 
Belgium, 523. 

Bronteus Halli, H. Woodward, sp. nov., 
408. 

Broom, Dr. R., Fossil Horse, 
Africa, 131. 

Brydone, R. M., New Chalk Polyzoa, 4, 
76, 145, 258, 390, 481. 

Bryozoa, Catalogue of, British Museum, 
321. 

Buckman; S2)S:, 
Ammonites, 430. 

Bullen, Rev. R. A., Molian Deposits, 
Morbihan, 6, 97; Z#. meridionalis, 
Dewlish, 334. 

Bullerwell, R. G. A., Superficial Deposits 
of Cheviots, 452, 

Buried Valley, Flamborough, 356. 


in, 439, 488, 


Origin of, 460, 626, 


South 


Yorkshire Type 


ABNOZOIC Mammal Horizons, North 
America, 524. 
Cairo, Building Stones of, 525. 
California, Earthquake in, 476. 
Cameron, A.C. G., Lyme aps Ca 
479. 
Canada Department of Mines, 431. 
Canadian Coal-fields, 91. fa 


3= 
37 


578 


Cape Colony, 140, 189. 

Carboniferous, Lower, Classification of, 
562. 

Carboniferous Arachnida, 505. 

Carboniferous Limestone, Coral. Zones 
inal, Wil. 

Carboniferous Limestone, 
Fauna of, 67. 

Carnivores’ from Miocene ot Western 
Nebraska, 524. 

Carrock Fell, Pegmatites of, 19. 

Carruthers, R. G.,, Coral Zones in 
Carboniferous Limestone, 171. 

Cautley, Yorkshire, Graptolitic Zones, 
473 ; Lower Paleozoic Rocks of, 474. 

Caves, etc., of Belgium, 6528. 

Jentenarian Geologist, 480. 

Cephalopods from the Chalk, Lincoln- 
shire, 345. 

Chalk, Lincolushire, Cephalopods from, 
345. : 

Chalk Downs in Kent, Sculpturings 
of, 49. 

Chalk Flint, Fossil in, 
Norfolk, 483. 

Chalk Fossils, Pocket-Guide to, 90. 

Chalk Polyzoa, 4, 76, 145, 258, 390, 


Llantrisant, 


Sherringham, 


481. Aan 
Chandler, R. H., Drift, Bostall Common, 
534. ‘ 
Chelonian from Purbeck, Swanage, 311, 
381. ; 
Cheviots, Superficial Deposits of, 452. 
Chicago, Journal.of Geology, 478. 
Christy, M., Mineral Waters of Essex, 


288. 

Cirripede — Pollicipes levis, Sby., 
Cretaceous, 495. 

Cirripedes, New Chalk, 151. 

Clark, J. ‘W., Obituary of, 527. 

Clinch, G., Sculpturings of Chalk 


Downs, 49. 

Clough, C. T., and others, Augen Gueiss 
and Moine Sediment, 337. 

Coal Basin of Central France, 229. 

Coal-measures, Yorkshire, etc., 471. 

Cockroach, South Wales Coal-field, 
S]te GH, WAS 

Cole, G. A. J., Aids in Practical 
Geology, 88. 

Colonsay, Geology and Natural History, 
328. 

Coral Zones, Carboniferous Limestone, 
efile 

Cotteswold Naturalists’ Field Club, 525. 

Crampton, C. B., and others, Augen 
Gneiss and Moine Sediment, 337. 

Creechbarrow Hill, Bembridge Fossils 
on, 436. 

Cretaceous of Pondoland, 132. 

Cretaceous Plants, 377. 

Cretaceous Rocks, New Cirripedes, 151. 


Index. 


Cribrilina claviceps, KR. M. Brydone, 
sp. nov., 390. 

C. Filliozati, R. M. Brydone, sp. nov., 
391. 

C. furcifera, R. M. Brydone, sp. noy., 
391 


Crick, G. C., Cephalopods from the 
Chalk, 345 ; Type-specimens of Ammo- 
nites cordatus and A. excavatus, Sby., 
503. : 

Crinoidal Limestone and Transition Beds, 

Wimani, 


275. 
F. R. C. Reed, 
sp. nov., 294. 


Crisinella 

Crook, T., Laterite and Bauxite, 233. 

Crystalline Structure and Chemical Con- 
stitution, 282. 


pees J. R., Obituary of, 575. 


Darwinian Theory, 192. 

Davison, C., British Harthquakes, 315, 
410. 

Deeley, R. M., Glacier Granule- 
markings, 112; Structure of Glaciers, 
433; The Plasticity of Rocks, 501. 

De la Torre’s Discovery of Fossil 
Mammals in Cuba, 512. 

Delépine, G., Fauna of Carboniferous 
Limestone, Llantrisant, 67. 

Deptford and Catford, Sections from, 
377. 

Derbyshire, Olivine Nodules in Basalt, 1. 

Derbyshire Coal-field Fossils, 474. 

Devonian, Eifel, Bronteus Halli, sp. nov., 
407. 

Dibley, G. E., Marsupite Chalk, 432. 

Discoidea, Jaw Apparatus, 141. 

Dixon, E. E. L., Titterstone Clee Hills, 
458. 

Dolgelley Gold-belt, 159, 201, 261. 

Dolomites in South Tyrol, 426. 

Dowling, D.B., Canadian Coal-fields, 91. 

Dreikante, Egyptian Desert, Formation 
of, 394. 

Drift, Bostall Common, 534. 

Dutton Shales, New Fossils from, 211, 
294, 

Dyson, W. H., Marine Beds at Maltby, 
520. 


| aa Face of the, 178. 


Earth-movements, 130. 

Earthquake in California, 1872, 476. 

Earthquakes, British, 315, 410. 

Edinburgh, Royal Scottish Museum, 132. 

Egerton, Rev. W. H., Obituary of, 287. 

Egypt, Origin of Nile Valley, 385 ; 
Geological Map of, 571. 

Elephas meridionalis, Dewlish, 334. 

Eocene, Egypt, Fishes from, 402. 


Index. 


Erosion and Deposition by the Indus, 289. 

Erosion on the Coast of Mull, 353. 

Essex, Mineral Waters of, 288. 

Etel, Morbihan, Afolian Deposits, 6, 97. 

Europe and America, Land-bridge 
between, 28. 

Evans, J. W., On Laterite, 189, 381. 


ALCONER, J. D., Geology of 
Northern Nigeria, 519. 

Fauna of Carboniferous 
Llantrisant, 67. 

Fayum, Egypt, Pholas-borings from, 398. 

Finlayson, A. M., Ore-bearing Peg- 
matites, Carrock Fell, 19; Otago 
Goldfields, 88; Petrology of Huelva, 
Spain, 220. 

Fishes from the Kocene, Egypt, 402. 

Flamborough, Buried Valley, 356. 

Flett, J. S., Augen Gneiss and Moine 
Sediment, 337. 

Flora and Fauna, Post-Pleistocene, 542. 

Foliated andnon-Foliated Rocks, Southern 
Nigeria, 529. 

Formation of Dreikante, Egyptian Desert, 
394, 

Fossil Flora of Bristol Coal-field, 58. 

Fossil Plants, Gloucester Coal-field, 241. 

Fossils from the Dufton Shales, 211, 294. 

Fox-Strangways, C. E., Obituary of, 235. 

Hrazer,) Or: iP: , Physical Properties ot 
Minerals, 478. 


Limestone, 


(CoD ila 1 ay | Jeleravaon on 
Archeosigillaria, 117. 

Gaspé, Sketches of, 376. 

Geikie, Sir A., Geological Map of 


Scotland, 182. 

Geological Society, Liverpool, Retrospect 
of Fitty Years’ Work, 524. 

Geological Society of London, 40, 92, 
33. UGG, sis AUS) Wiss, ei, ws 
284, 285, 331, 378, 572; ‘Additions to 
Library, 92; Medals and Awards, 
1910, ‘96. 

Geological Survey, British, Maps, Price 
of, 05; Memoirs, 37, 38, $2, 84,181, 
326, 368, 369, 567. 

—— Canada, 91. 

Egypt, 525; Map of, 571. 

New Jersey, 92. 

New Zealand, 131. 

Transvaal, 5245; Transvaal Mines 

Department, Memoirs, 130. 

Western Australia, 89. 

Geological Time, 132. 

Geologists’ Association, Jubilee Volume, 
124, 370, 428. 

Geology and Civil Engineering, 524. 

German South Polar Expedition, 8 35. 

Gibson, W., Coal-measures of Yorkshire, 
etc., AT. 


579 


Glacial Drift near Amroth, 279. 
Glacial History of Western Europe, 
463, 513. 
Glaciation of Navis Medley! 244, 
Glaciation in the United. States,-280. 
Glacier Granule-markings, 112. 
Glaciers, Structure of, 112, 433. 
Glastonbury Lake- dwellings, 480. 
Gloucestershire Coal- field, Fossil Plants, 
241. 
Gold-belt of To keellege 159, 201, 261. 
Gordons er Or Dolomites, South 
Tyrol, 425. 
Gotlandian of Fyledal, Gotland, 131. 
Graptolitic Zones, Yorkshire, 473. 
Gravels, Wind-worn Pebbles in, 299. 
Great Oolite Section, Oxfordshire, 537. 
Gregory, J. W., South-West Highlands 
of Scotland, 119; Fossil Bryozoa, 
Brit. Mus., 321; Geology, 372. 
Guiana, British, ‘ Laterite’ m, 439, 488, 
d00. 
Gunn, R. Marcus, Obituary of, 191. 


io ae A. L., Geology of Pilgrims 
Rest Gold-mine, 328; Geology of 
Zeerust and Mafeking, 525. 

Halos, Pleochroic, 15. 

Hampshire, Water Supply of, ete., 368. 

Harrison, J. B., ‘ Laterite’ in. British 
Guiana, 439, 488, 553. 

Hatch, F. H., Mines of Natal, 372. 
Hawkins, H. L., WDiscoidea, 141; 
Ambulacra in the Holectypoida, 349. 
Heslop, M. K., pre-Tertiary Dyke, 
Usway Burn, 104. 
Highlands of Scotland, 

South-West, 119. 

Hill, A., Erosion and Deposition by the 
Indus, 289. 

Hind, Dr. W., Awarded Keith Gold 
Medal, Edinburgh, 528. 

Hobbs, W. H., Earthquake in California, 
1872, 476; Inland Ice of Arctic 
Regions, 478. 

Hobson, B., Price of British Geological 
Survey Maps, 94. 


Problems otf 


| Holectypoida, Ambulacra in, 349. 
| Homalonotus ascriptus, EF 


R. C. Reed, 
sp. noy., 216. 

Horse Fossil, South Africa, 131. 

Horwood, ie R., Aragonite in, Middle 
Lias, 173; Transition Beds and 
Crinoidal Limestone, 274; Origin of 
British Trias, 460, 574 ; Post-Pleisto- 
cene Floral Fauna, 542. 

Howe, E., Landslides, San Juan Moun- 
tains, 477. 

Hume, Dr. W. F., appointed Director 
of Geological Survey of Egypt, 96 ; 
Tron Ores, Egypt, 131; Origin of Nile 
Valley, 385 ; Building Stones of 


580 


Cairo, 525 ; Geological Map of Egypt, 
Dias 
Hungary, Soils of, 129. 


CE Age in India, 193. 


Ice of Glaciers, 112, 433. 

Icebergs and Inland Ice ot the Antarctic, 
524. 

Igneous Rocks of the Red Sea, 334 

Index Generum et Specierum Animalium, 
519. 

India, Ice Age in, 195. 

Indian Geological Survey, Vacancies on, 
480. 

Indus, Erosion and Deposition by the, 
289. 

Inferior Oolite Vertebrates, 272. 

Tron Ores, Egypt, 131. 

Iychenko, A., Atolian Deposits, 522. 


ACKSON, J. W., <Archeosigillaria 
) in Westmorland, 78. 
Jehu, T. J., Swiney Lectures on Geology, 
1910, 528. 
Johns, Cosmo, Classification of Lower 
Carboniferous, 562. 
Johnson, D. W., Glaciation 
United States, 280. 

Johnson, T. P., Ore Deposits of South 
Africa, 90. 

Joly, J., Radioactivity and Geology, 122. 

Jones, O. T., as Lecturer in Geology, 
Aberystwith, 48. 

Jubilee Volume, Geologists’ Association, 
124, 370, 428. 

Juritz, C. F., Soils of South Africa, 129. 


in the 


i ARROO, South Africa, Fossil 
Vertebrates of, 131. 

Keeping, H. , Bembridge Fossils, Creech- 
barrow Hill, 436. 


Kilmarnock Museum destroyed by fire, 


Klaassen, U. M., Obituary of, 191. 

Koenen, Dr. A. v., Tertiary, North-West 
Germany, 130. 

Kiimmel, H. B., Geology, New Jersey, 
92. 


Wie eee Glastonbury, 
480. 

Lamplugh, G. W., Geology of Melton 
Mowbray, 181; Presidential Address, 
329. 


Landslides, San Juan Mountains, 
Colorado, 477. 
Lane, Rev. G. J., Jurassic Plants, 


Yorkshire, 574. 

Lankester, Sir E. R., ‘Treatise on 
Zoology (Fishes), 125 ; Monograph of 
Okapi, Atlas, 522. } 


Index. 


Laterite, The term, 139, 189, 335, 381. 

Laterite and Bauxite, 233, 382. 

Laterite in British Guiana, 439, 488, 
553. 

La Touche, T. H. D., Ice Age in India, 
193. 

Leach, A. L., Glacial Drift near Amroth, 
279; Bagshot Beds, Shooters Hill, 
405. 

Leckhampton Hill, 
101. 

Leicestershire, Aragonite in Middle Lias, 
1738. 

lueney, “E., appointed Curator Norwich 
Museum, 527 

Lias, Middle, Ag agonite in, 173. 

Libyan Desert, Sand-Dunes of, 477. 

Lignite of Bovey Tracey, 424. 

Lillie, D. G., Fossil Flora ot Bristol 
Coal-field, 48. 

Little River Group, Geology of, 283. 

Lloyd Morgan, Professor C., Geology of 
Bristol, 92. 

London District, Geology and Maps of, 
567. 

Lower Carboniferous, Meathop Fell, 117. 

Lower Carboniferous, Yorkshire, 562. 


Well-Sinkings at, 


. Lower Paleozoic Rocks, Yorkshire, 474. 


Lyme Regis Church, 479. 


Moree M., 
328 


Maltby, Marine Bands at, 520. 

Mammals in Cuba, Fossil, 512. 

Mammoth Cave, Western "Australia, 240. 

Man as an Instrument of Research, 329. 

Manson, M., PleistoceneGlaciations, 419. 

Maps, Geological, London, 567; and 
others, 572. 

Marine Reptiles, Oxford Clay, 564. 

Marr, J. E., Lower Paleozoic Rocks, 
Yorkshire, 474. 

Marsupite Chalk, Surrey, 432. 

Martin, E. A., Brighton “Cliff Formation, 
290. 

Matthew, G. F., 
132; Geology 
Group, 283. 

Maute, H. B., appointed Director of 
Geol. Survey, Southern Rhodesia, 384. 

Melton Mowbray, Geology, 181. 

Mem. Geol. Surv., see Geol. Surv. Mem. 

Membranipora anguiformis, RR. aM 
Brydone, sp. noy., 146. 

M. anterides, R. M. Brydone, sp. noy., 4. 

M. Britannica, var. demissa, KR. M. 
Brydone, var. nov., 77. 

M. Britannica, var. precursor, R. M. 
Brydone, var. nov., 77. 

M. coralliformis, R. M. Bayan; sp. 
noy., 259. ‘ 

M. dalinm, R. M. Brydone, sp. nov., 146. 


Colonsay, Tebrides, 


Phosphate Deposits, 
of the Little River 


Index. 


Membraniporahumiliata, R. M. Brydone, 
sp. nov., 4. 
nie invigitata, R. M. Brydone, sp. noy., 


Mu. Beit. R. M. Brydone, sp. noy., 
147. 

M. sagittaria, R. M. Brydone, sp. noy., 
1465. 

M. Woodwardi, R. M. Brydone, sp. nov., 
258. : 

Membraniporella fallax, R. M. Brydone, 
sp. noy., 482. 

M. pustulosa, R. M. Brydone, sp. nov., 
483. 

Mennell, F. P., Pleochroic Halos, 15 ; 

Miner’s Guide, 373; Petrology, 570. 

Mineralogical Society, London, 137, 233, 

380. 

Miner’s Guide, 373. 

Mines of Natal, 372. 

Mining Magazine, 91. 

Miocene of ‘Oregon, 130: 

Monckton, H. W. , Geology in the Field, 
124, 

Moysey, Dr. L., Fossils, 
Coal-field, 474. 

Mylomyrus frangens, A. S. Woodward, 
gen. et sp. noy., 404. 


Derbyshire 


ee ZEALAND Geology, 88 ; 
Wakatipu District, 130. 

Newport, Mon., Geology of, 38. 

Newton, R. B., A Wealden Anodonta, 
5265. 

Nigeria, Northern, Outlines of Geology 

of, 519. 

Nigeria, Southern, Foliated and non- 

Foliated Rocks, 529 

Nile Valley, Egypt, Origin of, 385. 

Nile Valley and Gulf of Suez, Origin of, 

(ils 

Nopesa, F., On Zitanosaurus, 261. 

North ‘America, Water of Great Lakes 
of, 376 

North Wales, 
201, 261. 

Norwich Castle Museum, 141; 
Curator appointed, 527. 

Nottingham, Organic Remains in Trias 
of, 229, 

Nottinghamshire, East, Upper Keuper 
Sandstones, 302. 


Dolgelley Gold-belt, 159, 


New 


BITUARY: H. Bauerman, 46; 

Rev. G. F. Whidborne, 141 ; 
R. M. Gunn, 191; H. M. Klaassen, 
Iie Ch Ww, Fox- Strangways, 285; 
A. Agassiz, 238 ; Rev. W. ie Egerton, 
Siok. Bs Whitfield, 336: W. P. 
Blake, Bedes Jo Wc Clark, 527: Wolie 
Dakyns, 575. 

Okapi, Monograph of the (Atlas), 522. 


581 


Olivine Nodules in Basalt, Derbyshire, 1 

Ore Deposits, Finland, 130. 

Ore-bearing Peematites, Carrock Fell, 
19. 

Organic Remains in Trias, 229. 

Origin of British Trias, 460, 526. 

Orthis Duftonensis, F. Ch Reed, 
sp. nov., 295. 

O. (Scenidium?) equivocalis, F. R. C. 
Reed, sp. nov., 297. 


O. melmerbiensis, F. KR. C. Reed, 
sp. noy., 296. 
Osborn, H. F., Cenozoic Mammal 


Horizons, 524. 
Oswald, F., Geology of Armenia, 283. 
Otago Goldfields, New Zealand, 88. 
Oxford Clay, Marine Reptiles of, 564. 
Oxford Wall Maps, 572. 
Oxtordshire, Great Oolite Section, 537. 
Oxtordshire, Water Supply ot, 369. 


ACHY DISCUS farmeryi, G. C. 
Crick, sp. noy., 340. 

Palzontographical Society’ s Monographs, 
1909, 128. 

Park, Professor J., Wakatipu District, 
New Zealand, 130. 

Parkinson, J., Foliated and non-Foliated 
Rocks, Southern Nigeria, 529. 
Peach, B. N., and others, Geology of 
Mid Argyll, etc., 37. 
Peematites, Carrock Fell, 
19. 
Peloneustes philarchus, Seeley, sp., 110. 
Peters, O. A., New Carnivores, Miocene, 
West Nebraska, 524. 

Petrology, Introduction to, 570. 

Petrology of Huelva, Spain, 220. 

Philippine Islands, Mineral [Resources 
of, 

Pholas-borings in the Fayaim, Egypt, 
398. 

Phosphate Deposits, 
152. 

Plant Impressions, Fossil, 473, 574. 

Plants, Fossil, Textbook of, 324. 

Plasticity of Rocks and Mountain 
Building, 501. 

Pleistocene Geology, Chicago, 90. 

Pleistocene Glaciations, 419. 

Pleochroic Halos, 15. 

Pliosaur, Peloncustes philarchus, 110. 

Pocock, R. J , Carboniferous Arachnida, 
505. 

Pollicipes, Trimmingham Chalk, 527. 

P. corrugatus, H. Woodward, sp. noy. 
(syn. P. concinnus), 527. 

P. imbricatus, T. H. Withee: sp. Noy. 
496. 

P. levis, Sby., 495. 

Polyzoa, New Chalk, 4, 1G U5) 258; 
390, 481. 


Ore-bearing, 


South Carolina, 


582 


Post-Pleistocene Flora and Fauna, 442. 

Practical Geology, Aids in, 88. 

Pre-Tertiary Dyke, Usway Burn, 104. 

Provence Fossil Invertebrates, 240. 

Pseudostega Cantiana, R. M. Brydone, 
gen. et sp. nov., 260. 

Purbeck, Swanage, Chelonian from, 311. 


eae oe and Geology, 

Randall, J., 100th Birthday, 480. 

Reed, F. R. C., New Fossils from 
Dufton Shales, 211, 294, 

Reid, C. and E. M., Lignite of Bovey 
Tracey, 424. 

Reptiles, Marine, Oxford Clay, 564. 

Rhagasostoma Novaki, R. M. Brydone, 
sp. noy., 390; var. dAnglica, R. M. 
Brydone, var. nov., 390. 

Richardson, L., Wells at Leckhampton 
Hill, 101; Inferior Oolite Vertebrates, 
272; Great Oolite Section, Oxtford- 
shire, 4537; Rhetie and other Strata, 
Somerset, 572. 

Rocks, Plasticity of, 501. 

Rogers, A. W., Cape Geology, 140. 

Ross-shire, Augen Gneiss and Moine 
Sediment, 337. 

Royal Society, Edinburgh, 
Medal, 528. 


Keith Gold 


JALISBURY, R. D., Pleistocene in 

\) Chicago, 90. 

Sand- Baryées, Kharga, Egypt, 377. 
Sand- Dunes of Libya an Desert, 477. 

Siaipeiuun aceumulatum, T. ee Withers, 
sp. noy., 152. 

S. aduncatum, T. H. Withers, 
156. 

S. comptum, T. H. Withers, sp. nov., 
153. 

S. cyphum, T. HW. Withers, sp. nov., 
155. 

S. dissimile, 
157. 

Scharff, R. F., Land-bridge between 
Kurope and America, 28. 

Scotland, Geological Map of, 182. 

Serivenor, J. B., Laterite and Bauxite, 
139, 335, 382. 

Sculpturings of Chalk Downs in Kent, 
49. 

Sedgwick Museum Notes, 211, 294, 436. 

Seward, A. C., Text-book of Fossil 
Plants, 324. 

Seymour, H. J., Professor of Geology in 
University College, Dublin, 48. 

Sheppard, T., Buried Valley, Flam- 
borough, 356. 

Sherborn, C. D., Index Animalium, 519. 

Sherringham, Norfolk, Fossil in Chalk 
Flint, 483. 


Sp. NOV., 


T. H. Withers, sp. nov., 


| Swinnerton, H. 


Index 


Shooters Hill, Kent, Bagshot Beds, 405. 

Shropshire, Geology of Titterstone Clee 
Hills, 458. 

Skeats, E. W., Volcanic Rocks 
Victoria, 525. 

Slimon, R., a Lanarkshire Geologist, 143. 

Smith, B., Upper Keuper Sandstone, 
East Notts., 302. 

Smith, W. 1 Mineral Resources of 
Philippine Islands, 91. 

Solea eocenica, A. S. Woodward, sp. nov., 
402. 

South Africa, Ore Deposits of, 90 ; Soils 
of, 129. 

South Polar German Expedition, 85. 

Spain, Petrology of Huelva, 220. 


of 


| Spencer, Dr. J. W., Fossil Mammals in 


Cuba, 512. 

Sphenopteris ovatifolia, D. G. Lillie, 
Sp. nov., 62. 

Steginopora denticulata, R. M. Brydone, 
sp. nov., 481. 

S. Gravensis, R. M. Brydone, sp. noy., 
481 


Stevenson, J. J., Coal Basin of Central 
France, 229. 

Stille, H., Icebergs and Inland Ice ot 
the Antarctic, 524. 

Stopes, M. C., Fossil Plant Impressions, 
473. 

Strahan, A., Geology of Newport, Mon., 
38; Geology of South Wales Coal- 
field, 326. 


| Strutt, R. J., Luminosity of Uranium, 81. 
Sub- Antarctic Islands of New Zealand, 


426. 

Suess, E., The Face of the Earth, 178. 

Suez, Gulf of, and Origin of Nile Valley, 
Ake 

Summary of Progress, Geological Survey, 
427 


| Superficial Deposits of Cheviots, 452. 


Swiney Lectures, 1910, 528. ee 
H.; Organic Remains in 
Trias, 299, 


HALL, Dr. J. J. H., Advisor on Soils 
to Board of Agriculture, 376. 


| Temperature of Earth, 130. 


Tertiary Beds, 
130. 

Thrust-masses of the Dolomites, 425. 

Tiddeman, R. H., Water Supply of 
Oxfordshire, 369. 

Tirol, Glaciation of Navis Valley, 244. 


North-West Germany, 


| Titanosaurus, Systematic Position of, 


261. 


| Titterstone Clee Hills, Geology of, 488. 


Transition-bed and Crinoidal Limestone, 
274. 


| Transyaal Gold Mining, 328. 
| Trias, British, Origin of, 526, 574. 


Index. 


Trinucleus Nicholsoni, F. R. C. Reed, 
sp. nov., 212. 

Tschokusu Plateau, Ravines of, 89. 

‘Tungsten-ores, 19. 

Tutton, A. E. H., Crystalline Structure 
and Chemical Constitution, 282. 


PPER Cretaceous, Dinosaur, Titano- 
saurus, 261. 
Upper Keuper Sandstones, EK. Nottingham, 
302 


Uralite and Amphiboles, Development, 
357. 

Urals, Geological Researches in, 376. 

Uranium, Spontaneous Luminosity of, 


81. 

Ussher, W. A. E., Geology of Bodmin 
and St. Austell, 84. 

Usway Burn, pre-Tertiary Dyke, 104. 


ERTEBRATES, 
272. 

Victoria, Volcanic, Rocks of, 525. 
Victorian Fossils, 377. 


Inferior Oolite, 


ADE, A., Igneous Rocks, Red Sea, 
334; Formation of Dreikante, 
394. 
Wales, South, Coal-field, 326. 
Wanderer, K., Guide to Chalk Fossils, 
90. 
Waterberg Tin-fields, 130. 
Watney, G. R., Graptolitic Zones, 
Yorkshire, 473. 
Watson, D. M. A., 
Purbeck, 311, 381. 

Well-Sinkings at Leckhampton Hill, 
101. 

Western Australia, Phillips River Gold- 
field, 89. 

Westmorland, Archeosigillaria in, 78. 


Chelonian from 


583 


Whidborne, Rey. G. F., Obituary of, 
IZal, 

Whitaker, W., Water Supply of Hamp- 
shire, 368. 

White, H. J. O., Geology of Basingstoke, 
82 


Whitfield, R. P., Obituary of, 336, 

Wills, L. J., Wind-worn Pebbles, 299. 

Wilmore, A., Development of Uralite 
and other Amphiboles, 357. 

Wind Erosion, Coast of Mull, 353. 

Wind-worn Pebbles in Gravels, 299. 


| Withers, T. H., New Chalk Cirripedes, 


151; Pollicipes imbricatus, sp. nov., 
496. 


| Woodward, A. 8., Eocene Fishes, Egypt, 


402. 

Woodward, B. B., Catalogue of Books, 
etc., in Natural History Museum, 475. 

Woodward, H. P., Phillips River Gold- 
field, 89. 

Woodward, Henry, Pholas-borings from 
the Faytim, 398; Bronteus Halli, 
Kifel, 407; Fossil in Chalk Flint, 
483 ; Pollicipes, Trimmingham Chalk, 
527. 

Woodward, Horace B., Geology of 
London District and Maps, 567. 


| Wright, W. B., Origin of British Trias, 


526. 


A ee eae Type Ammonites, 430 ; 
Fossils, 431 ; Coal-measures, 471 ; 
Geologists and Editors, 479. 
Young, A. P., Glaciation of 

Valley, 244. 


Nayis 


EERUST and Mafeking, Geology of, 
625. 
Zoological Society of London, 287. 
Zoology, Treatise on Fishes, 125. 


ERRATA. 


p. 53, 1. 3 of “‘ River SysTems”’. 
For Terl read Test. 


p. 368, middle. 


For them 7ead the rivers. 


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