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—__
I.—On tarce TERRESTRIAL SauRIANS FROM THE Ru@tTI0 Beps
or Werpmore HILL, DESCRIBED AS AvatoniId SANFORDI AND
Picrovon Herveri.
By H. G. Szexey, F.R.S., Professor of Geology in King’s College, London.
(PLATE I.)
N 1894 Mr. W. A. Sanford described, in the Proceedings of the
| Somerset Archeological Society (vol. xl, 1894, p. 284), the
geological circumstances of the discovery of a large fossil reptile.
- The fossil bones were found by the Rev. Sydenham H. A. Hervey
and himself in the Rheetic beds in the parish of Wedmore, in the
Vale of Glastonbury; and compared to Megalosaurus in its large
size and carnivorous character. The remains were generously
presented to the British Museum (Natural History) at South
Kensington. I have now to redeem a promise made by Mr. Sanford
in his paper that I would name and describe the specimens.
The fossils comprise teeth, bones of the hind limb, dorsal and
caudal vertebree, and ribs. The discoverer remarks upon the way
in which the bones appear to have been broken, crushed out of form,
and scattered in the deposit. These results are partly due to
transport of the specimens at the time of deposition; and partly,
apparently, to movements of the strata associated with the uplifting
of the rocks in that part of England. _
Only two teeth were saved ; they indicate two distinct genera. One
tooth (p. 2, Fig. 1) is of a generalized Megalosaurian type, and has
the summit of the crown greatly worn with use, and rounded. The
crown is broad and thick, 12mm. wide and 7mm. in thickness;
but towards the base of the crown, the width from front to back
increases faster than its thickness. The anterior margin is rounded
from side to side, as well as convex from above downward. If any
serrations were ever developed, they were in the proximal part, which
is worn away. In type the tooth resembles Zanclodon and Euskele-
saurus. Those types agree with JJegalosaurus in the limitation of
the anterior serrations to the upper margin of the tooth in the lower
jaw. Mr. Sanford states that the root of the tooth crumbled, and
that portions of the lower jaw were found. Taken by itself the
DECADE IV.—VOL. V.—WNO. I. 1
2 Professor H. G. Seeley—Dinosaurs Jrom Rhetic Beds.
crown suggests affinity rather with Zanclodon than Megalosaurus.
The serrations on the hinder border are at right angles to the margin.
I refer this tooth to Avalonia, the fossil being found in Avalon, the
district associated with King Arthur and his Knights of the Round
Table.
Fic. 2.—Tooth of Prerodon Herveyi, Seeley.
Rhetic Beds: Wedmore (Vale of Glastonbury).
The second tooth (Fig. 2) is also represented by an imperfect
crown. It is from the lower jaw, but of a very different type. It is
4 inch long and +3; inch wide at the base. It is sharp-pointed and
slender, and the only tooth which at all resembles it in form is one
from the collection of the late Rev. P. B. Brodie, found near Warwick,
now in the British Museum (Natural History), which I refer to the
same genus. ‘This acuminate tooth, manifestly smaller than the
tooth of Avalonia, and imperfectly preserved, is flattened externally
and rather convex on the inner side, where there are ‘three or four
short slight ribs towards the lower half of the crown, which some-
what recall the ribs in the teeth of Suchosaurus, which the type
resembles in form ; but the crown differs from that genus in being
more pointed, and especially in having the anterior and posterior
margins serrated. The anterior serrations are limited to the summit
of the crown. Their general direction is at right angles to the
curved surface, but they have a perceptibly greater upward tendency.
The posterior serrations are also directed upward. ‘This constitutes
a distinct resemblance to Thecodontosaurus and a difference from
Megalosaurus, in which the serrations are at right angles to the
cutting margins of the tooth, as they are in the short crown of
Palgosaurus. ‘The nearest approximation to this kind of serration
is made perhaps by the French genus Dimodosaurus. But the
serrations, except for their direction, are similar to those of Megalo-
saurus, and there is no median ridge running down the length of the
tooth such as is figured by M. Gaudry. The tooth indicates the
genus Picrodon. I have therefore no doubt that the remains of the
skeleton preserved belong to two distinct though closely allied
animals, of which the second was the smaller.
The true nature of the larger animal, Avalonia Sanfordi, is indicated
by the remains of the femur and other parts of the hind limb. The
Professor H. G. Seeley—Dinosaurs from Rhetic Beds, 3
femur (PI. I, Fig. 1) is about 38 inches long. It is a moderately
strong bone, compressed from front to back, with the proximal and
distal ends in the same plane. ‘There is no trace of a sigmoid curve
such as is seen in Palgosaurus, and to some extent in Megalosaurus
and Dimodosaurus. The least transverse width of the proximal end
is 94 inches and the greatest width 104 inches. Of this width, at
least 24 inches is due to the inward direction of the convex articular
surface, which measures 6 inches from front to back in the middle of
the articulation, is flattened above, and is round from above downward
as it extends inward. Below the proximal articulation towards the
outer border, the front of the bone is impressed for a width of about
3 inches. This condition somewhat approximates to that seen in the
corresponding part of the femur of Huskelesaurus Browni; only in that
type the transverse expansion of the head of the bone is much less,
and the shaft of the bone is nearly cylindrical, shorter, and relatively
stouter. The lower border of this impression is an oblique ridge,
which passes downward and outward, but is not appreciably
elevated; it is 4 or 5 inches long, and is the only representative
of the proximal trochanter of Megalosaurus, which is scarcely
developed in Huskelesaurus and Palgosaurus, is almost lost in
Massospondylus and Dimodosaurus, and passes away in some Zan-
clodonts. This is one of the most distinctive characters of the bone.
Below the termination of the ridge the external lateral contour of
the bone is concave in length, and this causes the shaft to narrow
from a width of 7 inches to 5} inches in its middle length, below
which it widens again to 114 inches towards the distal end. The
middle length of the inner lateral border is occupied by a trochanter,
which is now broken away but had the backward direction seen in
carnivorous genera of Saurischia. Its broken base is a foot long,
is perfectly straight, and occupies the middle third of the length
of the bone. Above the trochanter the concave inner border
is approximately parallel to the convex external border. The
widening of the distal end of the bone is similarly due to an inward
extension of the bone below the trochanter in a concave contour.
This inner side is flattened and inclines slightly forward, being
supported by the large inner distal condyle. The length and
position of the lateral trochanter are distinctive; in Huskelesaurus
it occupies the middle of the bone, and in Massospondylus it is
towards the middle, but in both the African genera it is relatively
shorter, while in Palgosaurus and Megalosaurus the proximal
position of the trochanter is as pronounced as in Zanclodon; so that
this also is a distinctive feature of the bone.
The distal end is about 114 inches wide. In front there is a slight
concave longitudinal channel, slightly external to the middle width.
The distal extremity is truncated. The larger inner condyle seen
behind is 7 inches from front to back, and separated from the outer
condyle by a moderately deep concave channel about 2 inches wide.
The back-to-front measurement between the two channels exceeds
4 inches. The outer posterior surface external to the lesser condyle
is oblique, and has the usual compressed aspect.
4 Professor H. G. Seeley—Dinosaurs from Rhetie Beds.
The bone is manifestly that of a new Zanclodont Saurian, and the
pelvis and other parts of the skeleton may be expected to conform
to the types at Stuttgart and Tiibingen. The shaft of the femur is
much straighter than in Megalosaurus, and the other characters all
tend to remove the genus Avalonia from the types in which the
pubic bones are slender and rod-like, and refer it to types in which
those bones are flattened plates.
Only 16 inches of the proximal end of the left tibia is preserved.
The proximal end is greatly expanded, especially towards the anterior
crest of the bone. The proximal surface is truncated in the usual
way, and is triangular. It measures 12 inches from front to
back, and 9 inches from side to side behind, indicating, as the
femur is nearly a foot wide, that the fibula had the usual slender
form. The inner side of the bone is smooth and convex from
front to back; the fibular side has a shallow channel for the fibula.
The posterior side is concave in the middle width at the proximal
end. These characters are too few to greatly elucidate the characters
of the animal, but they are in harmony with the proximal end of the
tibia in the genera which have resemblances to the femoral bone.
The hind foot is evidenced by digital and terminal claw phalanges.
In all characters these bones are so remarkably like those which
I have figured in Huskelesaurus (Annals Nat. Hist., ser. vi, vol. xiv,
p. 332, 1894) that I can point to no differences between them.
The transverse width of the claw phalange removes the animal from
all allies of Megalosaurus. It is not quite so wide as the same bone
in Cetiosaurus, and conforms to the type of Zanclodon preserved at
Tiibingen. The digital phalanges are 252; inches long, as wide
behind, narrower in front; 15% inch deep behind, depressed in
front. The bone narrows superiorly, and has the trochlear ex-
tremities completely ossified. The claw phalange exceeds 4 inches
in length, being more than one-tenth of the length of the femur, and _
nearly twice the length of a penultimate phalange. Its articular
end is trapezoidal, fully 2 inches deep, and as wide below the middle.
The usual vascular grooves extend in arched curves along the sides
of the bone, and are continued transversely beneath the articular end.
The limb bones probably indicate an animal less than six feet high.
The vertebre preserved appear to indicate two animals. The
dorsal vertebre all agree in the anterior face being flattened
and relatively small, while the posterior face is concave and much
larger. In this they resemble the vertebre of Avalonia. But
since one type has the centrum 5 to 5} inches long, with the
anterior face 6 inches deep, while the posterior face is 8 inches
deep, I conclude that it indicates a distinct animal from the
second type, in which the centrum is 53 to 6 inches long, with
the articular faces vertically ovate instead of circular, 44 inches deep
in front, and 5 inches deep behind. After making all allowances for
the effects of compression and distortion, J am compelled to refer
the larger vertebra to the animal with the larger tooth, and suppose
that the animal with the smaller tooth was represented by the
smaller dorsal vertebra. The large size of the centrum exceeds
Professor H. G. Seeley—Dinosaurs from Rhetice Beds. 5
anything seen in British carnivorous saurians, and is especially
large as compared with the dorsal vertebra of Megalosaurus, in
which the vertebre are as unlike the fossil as are the limb-bones.
The large dorsal vertebra of Avalonia Sanfordi is somewhat crushed,
and has the body of the centrum unusually constricted, both at the
sides and the base. Above the middle of the side, and a little behind
the middle length, is a concave impression, pinching the sides till
they are about 3 inches apart. The flattened anterior face is not
well preserved, and the margin of the deeply concave posterior face
is rounded. The measurements indicate a moderate arching of the
back. The neural canal is 25%; inches high in front and 2 inches
wide ; behind it is wider than high.
The neural arch has a strong elevated capitular facet 2 inches deep
and 14 inch wide, vertical and flat, with the anterior border straight
and the posterior border convex. It is an elevation upon and ex-
pansion of the anterior buttress of the arch, just as the tubercular
facet (which is lost with the transverse process) is supported by the
posterior buttress, which is a narrow oblique ridge. Hence there is
a concavity between the facet and the ridge, which extends under
the transverse process. The large posterior zygapophyses extend
back beyond the neural spine ; and the buttresses below them, which
face obliquely outward and backward, are excavated for the reception
of the pre-zygapophyses. The neural spine is compressed and vertical,
about 38 inches from back to front and half an inch thick, though
there is no certain indication of its height. The transverse width
over the neural arch as indicated was ten inches. The height of the
vertebree up to the summit of the neural spine may have been
20 inches. The transverse elevation of the capitular facet an inch
above the base of the neural arch is a remarkable and distinctive
character. The large size of the vertebra is somewhat Cetiosaurian.
The ribs were strong: one fragment, more than 15 inches long, is
3 inches deep at the fracture towards the proximal end, where the
external surface is reflected somewhat backward, and as the rib
extends outward its plane becomes twisted, so as to present a wider
and oblique lateral superior surface, the measurement being about
15 inch at the fracture at the distal end.
The remainder of the vertebree are referred to Picrodon Herveyi.
They comprise dorsal vertebra, with the body of the vertebree com-
pressed from side to side, and relatively more elongated, but with
the front of the centrum narrower than the back. There is a distinct
suture between the neural arch and the centrum. And the neural
arch has strong upwardly converging buttresses, supporting the
transverse processes. The articular faces are deeper than wide; the
width does not exceed 44 inches.
A caudal vertebra, showing the base of the transverse process, has
the centrum about 5 inches long, and the base of the transverse
process 24 inches from front to back, by 14 inch deep. The articular
face is about 5 inches deep, by less than 4 inches wide, but the
preservation does not show whether chevron bones were developed
at the hinder border. A later caudal, with the articular surface
6 Professor O. C. Marsh—European Dinosaurs.
fully 24 inches deep and the centrum 4 inches long, has no
transverse process, and shows no indication of a chevron facet,
though the base of the articulation is somewhat thickened behind.
A still later vertebra has the centrum 3 inches long, and the articular
face 14 inch deep by 1;4;inch wide. The caudal vertebrae continue to
diminish in length, and the neural arch becomes compressed from
side to side, but remains well developed, and nearly an inch longer
than the centrum. The pre-zygapophyses look obliquely upward
and forward, and receive the wedge of the posterior zygapophyses
between them. There appear to be faint indications of very small
chevron bones in these latest vertebree. It is possible that the
smaller caudal vertebra belong to Avalonia.
These vertebral characters indicate an animal closely allied to
Avalonia, but well distinguished by the lateral compression of the
centrum, supported by the singular form of the tooth crown, obliquely
serrated at the margin, and ribbed on the inner side.
EXPLANATION OF PLATE I.
Avalonia Sanfordi, Seeley.
Fic. 1.—Anterior aspect of left femur. a, articular head ; 2, ridge representing the
trochanter major ; ¢c, broken base of the inner lateral trochanter; d, inner of
the larger distal condyle.
Fic. 2.—Posterior aspect of a dorsal vertebra.
Fie. 3.—Right side of a dorsal vertebra, showing (/) the capitular and (¢) tubercular
facets, and the xygapophyses.
Fie. 4.—Side view of claw phalange and penultimate phalange of hind foot.
Fie. 5.—Articular end of claw phalange.
Picrodon Herveyi, Seeley.
Fie. 6.—Dorsal vertebra, posterior aspect.
Fie. 7.—Same vertebra, lateral aspect.
Fic. 8.—Early caudal vertebra, lateral aspect.
Fic. 9.—Late caudal vertebra.
Rhetic Beds: Wedmore Hill (Vale of Glastonbury), Somerset.
See also note on some Rhetic Foraminifera from Wedmore, by F. Chapman,
1895, Ann. and Mag. Nat. Hist., vol. xvi, p. 306.
I].—Recent OBSERVATIONS ON LHuropkan DINOSAURS.
By Professor 0. C. Marsu, M.A., Ph.D., LL.D., F.G.S.;
of Yale College, New Haven, U.S.A.
URING the past summer, it was my privilege to attend the
International Congress of Geologists at St. Petersburg, as an
official delegate from the United States, and this gave me an
opportunity to see a number of museums and collections in
Europe which I had not before visited. I thus had the privilege
of inspecting personally many interesting reptilian remains that
I had not previously known, and of examining others which were
more or less familiar to me from figures and descriptions.
In the present paper, I have only time to speak of the Dinosaurs,
in which I have long taken a special interest, and have endeavoured
to study all the known specimens of importance, both in this
country and in Europe, having in view the preparation of a series
Professor O. O. Marsh—European Dinosaurs. 7
of memoirs on the different groups of this subclass of extinct
Reptilia.
London.—I began my investigations in the British Museum in
London, a great treasure-house for fossil reptiles, to which I have
long made frequent pilgrimages. This time the Dinosaurs were
seen to better advantage than ever before, but of new or unknown
forms I found that few had been added to the collection since
my visit two years ago; and I consoled myself with the other
extinct Reptilia, and especially with the new fossil birds and
mammals from South America.
St. Petersburg.—In St. Petersburg I hoped to find many Dino-
saurian remains, as here had been brought together an abundance
of fossil treasures from various parts of the Russian Empire, which
I knew must contain many forms of this group. In the four
principal museums of the city, however, I could find no bones
of Dinosaurs on exhibition, nor could I learn from any of the
museum authorities that such remains had been recognized among
the specimens received, neither could I find any such fossils myself
among the débris of the collections, so often a rich repository
for new or inconspicuous specimens. This was true also of the
smaller collections visited, and I was at last forced to admit that
here, at least, the Dinosaurs of Russia, like the snakes of Ireland,
were conspicuous only by their absence.
Moscow.—This opinion was not changed by a visit to the rich
geological collections of Moscow, which I examined with care ;
although other fossil vertebrates, including many reptiles, were
abundantly represented. I was assured, moreover, by various
Russian paleontologists, that in other museums of the empire or
in the known localities they had seen no Dinosaurian remains.
This vain quest, however, only proves that the discoveries are
yet to be made, and I confidently expect them at no distant day,
since in almost every other part of the world Dinosauria have
already been brought to light. In Northern Europe west of Russia,
and in North America to the east, these reptiles were especially
abundant, and the vast territory intervening must contain numerous
Dinosaurs, including many new forms of the group.
Vienna.—In Vienna I knew that my friend Professor Suess had
a large collection of Dinosaurs in his museum to show me, and
I spent several days there in their investigation. This collection
was of special interest to me, as it was from the Gosau fresh-
water deposits, which, as a student, years ago, I explored mainly
in the expectation of finding Cretaceous mammals; and I was
not without hope of still detecting such remains during my present
visit, as here were the localities where they were, in my judgment,
most likely to be found in Europe. The Dinosaurs I examined were
from Neue Welt in this formation, and were of great interest. They
had all been studied by Bunzel, Seeley, and others, who had recog-
nized ten or twelve distinct genera and many species among them.
I could find, however, not more than a quarter of this number, and
among these I found no indications of the Ceratopsia, which from
8 Professor O. C. Marsh—European Dinosaurs.
the published figures and descriptions I supposed to be represented
in this collection. The Dinosaurs with dermal armour which I saw
all pertained to the Stegosauria, and two distinct genera among them
were more nearly like Scelidosaurus of the English Jura and Nodo-
saurus of the American Cretaceous than any others with which J am
familiar. This collection contained the only Dinosaurian remains
I could find in Vienna.
Munich.—I next went to Munich, which, under Professor von
Zittel, has become a great centre for paleontology. I found that the
gem of the collection is still the unique Compsognathus, which in
several previous visits I had studied with care. A re-examination
impressed me even more with the fact, that this is one of the most
perfect and interesting vertebrate fossils yet discovered, and no other
example of the genus is known. It was in this unique specimen
that years before I had detected the embryo, and this fossil still
affords the only known evidence that Dinosaurs were viviparous.
I could find no other Dinosaurian bones of interest in the Munich
collection, the new features being mainly numerous fine specimens
of Mosasauria from America, and some interesting remains of
Hesperornis and Baptornis from the same horizon in Kansas.
I was much pleased to see here the new Jurassic fossils collected
by Nansen in 1896, at Cape Flora, in Franz Josef Land. These
interesting remains are now under investigation by Dr. J. F.
Pompeckj, assistant in the Munich Museum. I could detect no
vertebrate fossils among them, although various indications favour
their presence in this fauna.
Paris.—My limited sojourn in Paris gave me no opportunity for
a careful examination of the museums there, but I could learn of
no recent additions of Dinosaurian remains since my last visit.
Caen.—I next went to Caen, in Normandy, to see the famous
Dinosaur Poikilopleuron, so well described by Deslongchamps many
years ago. Through the kindness of my friend Professor A. Bigot,
I had a good opportunity to study this unique specimen, which of
late has been regarded as identical with the Megalosaurus of Buck-
land, the first genus of Dinosaurs described, and one about which
little is yet known. ;
Among the undetermined material of this museum, I was greatly
pleased to find the genus Pleuroceelus well represented by character-
istic fossils, and from a well-defined Jurassic horizon in the vicinity
of Havre. The species appears to be a new one, somewhat smaller
than Pleurocelus suffosus from the Kimmeridge of Swindon, England.
It resembled still more closely Plewrocelus nanus, which I have
described from the Potomac formation of Maryland.
Pleurocelus is one of the most characteristic genera of the Sauro-
podous Dinosauria, and its value in marking a geological horizon
should therefore have considerable weight. It is now known from
the two European localities mentioned above, both in strata of
undoubted Jurassic age. The same genus is well represented in
1 Lydekker records a Wealden species, Pleurocelus valdensis, in Quart. Journ.
Geol. Soc., 1890, vol. xlvi, p. 182, pl. ix.
G. F. Harris—Journey through Russia. 9
the Potomac deposits of Maryland, and has been found also in the
Atlantosaurus beds of Wyoming, thus offering, with the associated
fossils, strong testimony that the American and European localities
are in the same general horizon of the Upper Jurassic.
Havre.—The last day at my disposal before sailing for America,
I spent in Havre, in the Muséum d’Histoire Naturelle, where the
director, M. Lennier, showed me many vertebrate fossils of interest,
from the well-known localities near the city. Here, again, among
the fragmentary specimens not yet investigated, I found the bones of
another Dinosaur, also one of the Sauropoda, but considerably larger
than the Pleurocelus at Caen. The remains were very similar to
those of Morosaurus, and the horizon was, in the Kimmeridge, which
is here well defined.
From Havre, I crossed the Channel to Southampton, and with
a parting look at the Wealden cliffs of the Isle of Wight, which have
furnished the remains of so many interesting Dinosaurs, I sailed
for home.
TIJ.—NaARRATIVE OF A GEOLOGICAL JOURNEY THROUGH RUSSIA.
1. FInnanp.
By Gxo. F. Harris, F.G.8., M.S8.G.F., etc.
‘| ie meeting of the International Geological Congress at St.
Petersburg towards the end of August last year was about as
successful in promoting the main objects the Congress has in view
as any of its predecessors. ‘There was a marked absence of any-
thing like a serious radical programme, and in that sense the
meeting may be said to have been progressive. The majority of the
papers read were commonplace, the few exceptions being mostly in
the domain of petrology. Hvery geologist who attended the
meeting was grateful to the Organizing Committee for getting
together such a nice little exhibition of specimens, maps, and models
for the occasion. It was full of interest.
The official Russian geologists did everything in their power to
assist their visitors. They caused certain scientific institutions in
St. Petersburg to remain open longer than usual, and were never
tired of explaining the rich collections stored in the geological and
mineralogical museums in the Imperial University, and in kindred
museums. During the week of meeting they organized a day’s
excursion to the Czar’s palace at Peterhof, and another to the
renowned falls of Imatra—a long distance off, in Finland, but
distance counts as nothing in the Russian Empire. Then there
were the inevitable receptions, though, fortunately, these were not
carried out to the same extent as at the Washington Meeting.
But it was not of the actual Congress meetings, nor of the papers
read or mumbled before them, nor of the wonderfully preserved.
mammalian remains in the temporary museum, nor of the unvarying
courtesy of the Russian officials, that I desire to write in these
articles. Neither may I say anything in the GuotocicaL Macazine
concerning the social aspects of our visit to the other side of Hurope
10 G. F. Harris—Journey through Russia.
—of the many banquets held in our honour, of the terrible number
of speeches, mostly by self-elected “representative” spokesmen,
which frequently commenced shortly after the soup was placed upon
the table (so keen was the competition to do justice to our hosts!) :
these and many minor incidents, some of a distinctly sensational
character, would more fittingly be recorded in the pages of a three-
volume novel.
The Committee of Organization had arranged that four excursions
should take place in connection with the Congress meeting. Of
these, three were to be held before the meeting, viz.:—(1) to the
Urals, (2) to Hsthonia, (3) to Finland; and one after, namely (4)
to South Russia, by the Volga or alternative routes, over the
Caucasus through Tiflis to Baku (variations), thence to Batoum and
across the Black Sea, through part of the Crimea to Sebastopol, and
on to Odessa. I had the good fortune to be included amongst the
participants of journeys 38 and 4—to Finland and Transcaucasia;
and the aim of these articles is to give some account of the geology
along the lines of route pursued by those two parties. To begin
with the Finland journey ; and I prefer to write in narrative style.
Starting from St. Petersburg at night-time for Helsingfors, we
had no opportunity, then, of learning the character of the scenery
through which we passed. The next morning broke dull and grey,
and through the rain we could see that although the country was
flat it was extremely well wooded, and that the fields adjacent to the
railway track were strewn with enormous boulders. The country
was saturated with water, and the bracken fern and undergrowth
generally were doing their best to hand plenty of peat down to
posterity. Here and there was evidence of disastrous forest fires,
whilst numerous blackened stumps stood out of the peaty soil and
could be counted by hundreds in the clearings. Vegetation was not
only abundant, but luxuriant, and this in what is usually called
cold, icy Finland! And so we continued to Helsingfors, meeting
with but little else by the way except an occasional outcrop of granite.
At Helsingfors, Wilhelm Ramsay, of the University of that city,
met us. ‘This indefatigable geologist has done much for the geology
of the country adopted by his ancestors. His work in the Isle of
Hogland! and on the Quaternary deposits of Finland? may be cited
as examples, whilst he has written joint memoirs with H. Berghell ®
and E. T. Nyholm* on the petrography and stratigraphy of the
older rocks of Finland.
Helsingfors stands at the extremity of a small promontory, which
is composed of a heterogeneous mass of what, for want of a better
1 “Om Hoglands geologiska byggnad’’: Geol. Foren. Férh. Stockholm, Bd. xii,
1890. ‘‘ Beskrifning till kartbladen, No. 19 och 20, Hogland och Tytarsaari’’ :
Finl. Geol. Und. 1891.
; * “Ueber den Salpausselka im éstlichen Finnland,’’ Fennia 4, No. 2; Helsing-
ors, 1891.
3 “Das Gestein von Jiwaara in Finnland’’: Geol. Foren. Foérh. Stockholm,
Bd. xiii, 1891, p. 300.
* « Cancrinitsyenit und einige verwandte Gesteine aus Kuolajarvi’’: Bull. Comm.
Géol. de la Finlande, No. 1, 1895.
G. F. Harris—Journey through Russia. Il
name, is called gneiss or “granitic schist,” and the same class of
rock extends for many a square mile around, relieved only by
considerable extensions of overlying Glacial and Post-Glacial clays,
and sands. The gneiss is believed to be of Archean age. It is an
indescribable mixture, the so-called foliations resembling flow-
structure, leading one. to the belief that the whole was due to contact
metamorphism. In certain cases, where schistose fragments appear
to have been more or less absorbed, such an explanation is highly
probable ; but, except the “ Rapakivi,” practically all the granite of
South Finland, for at least 200 square miles, is foliated or
‘‘oneissose,” or ‘schistose.” Over large tracts appearances are
certainly in favour of differential movements in the magma. But
I will not say much about the rock, for our opportunities of
examining it in the field were very small. The islets which add so
much to the beauty of the environs of the Finnish capital are
constituted either of this gneiss or the “ gneissose granite.”
The courteous Director of the Geological Commission of Finland,
Mr. J. J. Sederholm, invited us all to the offices of the Survey,
where he had prepared a representative collection of rocks and
minerals, and examples of such fossils (all Quaternary) as have
been found in the country. Sederholm’s contributions to geology
are already important. Amongst other things he has prepared
a small geological map of Finland in two editions—solid and drift.
He has especially studied the “Rapakivi”! and Archean? rocks
of South Finland. During the past year or two he has been
engaged on the detailed mapping of the extremely interesting
country in the neighbourhood of Tammerfors.* In conjunction
with W. Ramsay, he prepared the useful guide* for the use of
members attending the Finland excursion.
The collection of specimens at the office of the Geological Com-
mission proved very interesting, and, in a measure, served as an
illustrated guide to the class of rocks which we were to study in the
field during the following week. Many types, however, did not lie
along our track; amongst these latter were marvellous examples of
“yapakivi” and some “globular” granites, and a word or two
respecting them may not be out of place.
The peculiar kind of “granite” known as rapakivi has, typically,
a number of large phenocrysts, commonly rounded or ovoid, com-
posed of a kernel of orthoclase enclosed within an envelope of
oligoclase (Fig. 1). The rock between these phenocrysts is fine-
grained and frequently micropegmatitic. The formation of the acid
' << Ueber die finnlandischen Rapakiwigesteine’’: Tscherm. Min. und Petrogr.
Mitth. Wien, Bd. xii, 1891.
2 « Archaische Eruptivgesteine a. d. stidwestlichen Finnland’’: id., Bd. xii,
1891. ‘Ueber einen metamorph. pracamb. Quarzporphyr von Karvia, Proving
Abo’’: Bull. Comm. Géol. Finlande, No. 2, 1896; ete.
3 “ Archiiische Sedimentformation im siidwest. Finnland’’: Bull. Comm. Géol.
Finlande, No. 6, 1897.
4 «Guide des excursions VII Congrés Géol. Internat. : XIII, Les Excursions en
Finlande’’; St. Pétersbourg, 1897.
12 G. F. Harris—Journey through Russia.
before the more basic felspar in the phenocrysts, and the detailed
structure accompanying that phenomenon, form a very instructive
study.
At the same time, the term rapakivi is largely applied by
the geologists of Finland to holocrystalline rocks of granitic type
Fie. 1,—‘‘ Rapakivi granite ’’ (4 nat. size). a=orthoclase; 6=plagioclase.
which contain large, rounded, and even. irregularly - shaped
phenocrysts of orthoclase, and which may not have the
triclinic felspar wrapping round them, except in very rare
instances in any one massif. It is used, in fact, as a general
field term for granites of that description of Pre-Cambrian age.
As thus defined, ‘“rapakivi granite” extends over enormous areas in
Southern Finland, on the north-eastern shore of Lake Ladoga, in
the little island of Hogland in the Gulf of Finland, and in the
Aland archipelago. It is one of the youngest of the Pre-Cambrian
eruptives in the country, and has been classified by Sederholm* in
his Jotnian formation—the younger subdivision of the Algonkian
(or Archzeozoic) group.
The “ globular granites” exhibited at the offices of the Geological
Commission (some of which were subsequently shown in the
temporary museum formed in connection with the Congress meeting
at St. Petersburg) have been described in some detail by Benjamin
Frosterus.2. The accompanying diagram (Fig. 2) represents one of
these rounded or ovoid bodies. Mr. Frosterus tells me that the
kernel is frequently formed of a fragment of biotite schist.
Following his observations in the work just quoted, it will be seen
that, normally, there is a kernel or nucleus, outside of which are
four successive zones. In the diagram (Fig. 2) a represents the
nucleus, which, in the specimen analyzed by Frosterus, contained
63-64 per cent. plagioclase (Ab, An,) with 18-92 of biotite and
19°60 of quartz. Then followed the first coating or andesine zone
(b), in which the plagioclase (Ab, An,) amounted to 73°22, biotite
8:00, and quartz 1650. The next coating, the oligoclase-andesine
zone (c), yielded plagioclase (Ab, An,) 56-07, biotite 5:60, and
quartz 89°72. This is succeeded by a microcline zone (d), in which
we have plagioclase (Ab, An,) 16°52, alkali-felspar 57-44, and
1 “¢Guide des Excursions,”’ etc. (op. cit.), p. 18.
2 “ Kugelgranit von Kangasniemi in Finland’’?: Bull. Comm. Géol. Finlande,
No. 4, 1896.
G. F. Harris—Journey through Russia. 13
quartz 26°74. The outermost zone (e) has plagioclase (Ab, An,)
44:28, alkali-felspar 6:79, biotite 4:00, quartz 42°82. The mineral
composition of the stone between the globular bodies is
plagioclase (Ab, An,) 385-49, alkali-felspar 16°88, biotite 12:27,
quartz 32°53. From this and from the chemical composition
of the different zones and the “ muttergestein,” it is evident that
the general tendency of the ordinary separation of the crystals from
the original magma was normal—that the zones, on the whole,
become more acid as they recede from the nucleus. The proportion
of Si O,, for example, in zone 6 is 61:64, ¢ 72-92, d 74-80, and e
75°67, whilst the rock between the globular bodies has 70:46. Not
the least interesting feature in these remarkable bodies is the
mechanical deformation to which they have occasionally been
subjected, and which has had the effect of breaking through the
zones and squeezing out some of the substance of the interior. In
certain of these Finnish “globular granites” shown at Helsingfors
the spheroidal and ovoid bodies have been partially absorbed by the
matrix in which they occur. The concentric zoning is clearly
marked, and in most cases the minute crystals are so arranged as to
produce a radiating effect.
Fig. 2.—‘‘ Globular granite.’’ Diagram showing disposition of zones _
in one of the typical ovoid bodies (about } nat. size). The dis-
tinguishing italics are explained in the text.
The structure of these bodies differs somewhat from that of the
well-known spheroids in the granite of Mullaghderg, County
Donegal, described by Dr. Hatch,! though the Finnish rock agrees
better with the Irish than with certain Continental rocks adverted
to by the last-mentioned author.
At length, after a stay of three days, it was time to leave
Helsingfors, and Mr. Sederholm took charge of the party. A long
railway ride north, to Tammerfors, and an enthusiastic welcome from
1 Quart. Journ. Geol. Soc., vol. xliv, 1888, p. 548 et sqq.
14 G. F. Harris—Journey through Russia.
the inhabitants of that manufacturing town were the first items on
the programme. The country seen on the way was flat or but
slightly undulating, with low hills occasionally ; the whole well
wooded and watered. The Glacial clays passed through shortly
after starting were here and there covered by Post-Glacial clays and
littoral deposits containing Litorina, Cardium, Mytilus, Tellina, ete.
A ridge of considerable size was traversed by the railway at
Hyvinkaa, which proves to be a large terminal moraine. To the
north of that place moraine gravels predominate, and there are
several asar, a phenomenon which I intend to describe more
particularly at another stage of our journey. Then several lakes
come into view, and Tammerfors with its hilly scenery is reached.
Tammerfors is situated on a narrow neck of land formed by an
“as,” which separates the lakes of Nisijirvi and Pyhajarvi. The
former lake is about 58 feet above the latter, and the two are con-
nected by rapids, which in parts are very beautiful. The journeys
for the next two or three days were from that place as a centre,
a special train being always at our disposal.
The neighbourhood of Tammerfors is excellent for studying the
Archean rocks of Finland. The following divisions are recognized
by Mr. Sederholm ? :—
1. Post-Bothnian granite.
2. Bothnian schists.
3. Pre-Bothnian gneiss.
In the last division, granites (essentially metamorphic), porphy-
roides, and closely foliated gneiss predominate. These latter,
according to Sederholm, are granitized mica-schists. All these rocks
crop out to the south of the town.
We examined the foliated granite and mica-schist (on the after-
noon of our arrival) in a railway cutting at Siuro, about twenty
miles west of Tammerfors; and in a railway cutting to the west
of Suoniemi we had an opportunity of examining the mica-schist
highly plicated. The micro-structure of these and some other
Finnish rocks will presently be described.
We will turn now to the second division—the Bothnian schists,
which, as will be seen as this narrative proceeds, we examined at many
points. The local development of these is known as the Tammerfors
schists. They crop out in bands running east and west, the whole
being highly inclined and limited by tie Pre-Bothnian gneiss on the
one hand and the enormous outcrops of the Post-Bothnian granite
on the other. These schists are often represented by phyllades,?
which occasionally approach true argillites and sometimes pass
gradually into fine-grained mica-schists. The foliated arkose, which
Mr. Sederholm calls “leptite” (to be more particularly referred to
hereafter), occurs in this subdivision. So also do certain hornblende
(mostly uralite) schists (called porphyritoides), which were
originally volcanic tuffs, and sometimes have altered lavas inter-
calated between them.
1 « Excursions en Finlande’’ (op. cit. supra), p. 2.
2 This term is here used in its broad sense.
Professor T. G. Bonney—Lake-basins in the Alps. 15
- But one of the most remarkable features of the ‘“ Bothnian
schists” in the neighbourhood of Tammerfors is the presence of
conglomerates on several horizons. ‘These, in many instances, are
so fresh that one finds some difficulty at first in believing that they
are really Archean. The waves of Lake Nasijirvi, in the lovely
bay of Hormistonlahti, where these conglomerates are well exposed,
have assisted the atmosphere in picking out the more or less
crystalline cement between the pebbles. In other situations these
Finnish rocks reminded me strongly of certain Cambrian
conglomerates in North Wales; but I do not desire to draw the
comparison any closer, for the Cambrian of the neighbouring parts
of Russia, as everyone knows, is peculiar. as being so little affected
by the ravages of time.
Mr. Sederholm places’ the thickness of the Tammerfors schists
at from 4,000 to 5,000 métres—2,000 métres for the phyllades,
1,500 for the lower tuffs and conglomerates, and the remainder for
the upper tuffs with their intercalations of phyllade and con-
glomerate.
The Post-Bothnian granite, which crops out to the north of the
schists in the Tammerfors area, is shown by Sederholm to traverse
the latter, veins being thrown out at certain places, and large pieces
of the schists being caught up at frequent points along the junction
between the two rocks. And these pieces of included rock, in
addition to possessing the structure and mineral composition of the
Tammerfors schists, have occasionally been discovered to contain
typical pebbles as found in the last-mentioned formation.
As I proceed with the narrative, I propose to give field notes
and some account of the micro-structure of examples of these
Archean rocks which I collected, and to deal with the Glacial
deposits, in the next article.
(To be continued.)
TV.—NOoTES ON SOME SMALL LAKE-BASINS IN THE LEPONTINE ALPS.
By Prof. T. G. Boynzy, D.Se., LL.D., F.R.S., V.P.G.S.
OCK-BASINS have been getting out of favour of late. The
“heckling”? which they have suffered from my friend
Mr. Marr tempts one to echo Betsy Prig’s classic remark about
Mrs. Harris. Mr. Brend, however, though “dealing faithfully ”
with them in the September number of the Gronocican Magazine,
does permit one or two to exist on sufferance, so that I feel minded,
were it only as an act of charity to these depreciated securities, to
describe two or three examples in the Alps which I think must be
true rock-basins.
The first is called the Lago Tremorgio.? It lies, at a height of
5,997 feet above the sea, on the southern flank of the Val Bedretto,
at the top of a long and steep ascent from Fiesso. It is slightly
irregular in outline, but circular in form, with a diameter between
1 Op. cit. supra, p. 4.
2 I examined it in 1893.
16 Professor T. G. Bonney—Lake-basins im the Alps.
seven and eight hundred yards. It is almost enclosed by steep
slopes and crags, and is entered through a narrow V-shaped gully,
with a rapidly rising ridge on either side. Through this gully runs
the stream which carries off the water of the lake. I followed
a track which mounts gradually up the right bank, and no blocked
outlet exists on that side; I had an excellent view of the other bank,
and feel certain there could not be one there. In fact, the rapid
rise of the rocky ridge on either side and its outline are almost
conclusive to an eye accustomed to mountain forms against there
South.
M4
ty
(
(
I nad
North.
Fre. 1.—Broken horizontal lines: Gneiss.
Vertical lines: Schists, micaceous, etc.
White: Water.
(Scale as below, Fig. 2, on p. 17.)
being any outlet to the cirque but the present one. At this the live
rock can be seen not only on either side but also in the bed of the
stream. Of that I could be sure, because the channel had been
deepened, apparently in order to add slightly to the pasture-land by
lowering the level of the lake, and had been cut down for about
four feet into the solid rock. Above the cliffs is an undulating tract
of pasture, forming a kind of step, on which is a small shallow
tarn, and from this rocky slopes lead to the crest of the range, the
lowest part of which, at the Passo Campolungo, is 7,595 feet above
the sea. Thus the Lago Tremorgio is enclosed between two lofty
spurs from the range, somewhat in the position of the seat of an
armchair.
The next rock-basin, the Lago Ritom! in the Val Piora, is on the
opposite side of the Val Bedretto, at almost exactly the same
elevation above sea-level.” Its position is remarkable. A mass of
crystalline schists, calcareous, quartzose, and micaceous, with some
overlying rauchwacke, are apparently infolded between two masses
of gneiss, of which the southern forms a high spur separating the
Val Piora from the Val Bedretto, and the northern belongs to the
watershed of the Lepontine Alps. Thus the Val Piora occupies
a kind of trough between these two masses of gneiss, which runs ~
1 T was there for some time last summer, and had already paid four short visits.
2 Tt is a few inches over 6,000 feet.
Professor T. G. Bonney—Lake-basins in the Alps. 17
almost from east to west, and its upper end descends from a bold
craggy peak, which is called the Pizzo Columbe, and is formed of
dolomitic limestone (a variety of the rauchwacke). On either side
of this peak gaps, about 7,800 feet in height, lead to the upper part
of the Lukmanier Road. After the first descent from these passes,
the bed of the valley falls rather gradually and is fairly open, the
mountains rising with moderate steepness on the southern side and
precipitously on the northern. Sheltered ina recess in the latter side,
just before we reach a break in the level of the valley, we find the
Lago Cadagno (6,303 feet). It occupies a kind of cirque or gigantic
corrie. Steep crags of gneiss sweep round about one half of it ;
North.
SS Ss See
(—-—— a SS aS
SS
= | Kilometer
South.
Fic. 2.—Broken horizontal lines: Gneiss, with garnet and actinolitic schists (in
northern part).
Vertical lines: Schists, micaceous, quartzose, and calcitic.
Coarse dotted: Rauchwacke.
Fine dotted: Alluvial.
White: Water.
the western end is barred by a spur, formed of an infold of
rauchwacke, followed by a mass of dark micaceous schist ; the former
corresponding with a slight depression, the latter with a hill. The
lake is nearly 900 yards from east to west, but a small marshy
plain shows that it has once extended rather farther in the latter
direction ; it is about 275 yards across. The stream draining it
flows from the south-west end. The character of the ground
makes it difficult to speak positively, and one or two low mounds
near the stream may be morainic, but the minor ridges in the
neighbourhood of the more open side are clearly live rock, and the
stream itself passes over the same at a level a very few feet indeed
DECADE IVY.—VOL. V.—NO. I. 2
18 Professor T. G. Bonney—Lake-basins in the Alps.
below that of the lake. Hence, even if the latter to some extent is
retained by drift, it may nevertheless, since it is not very shallow,
be claimed as a rock-basin.
A short distance from the Lago Cadagno, the level of the
valley, as already stated, is interrupted by cliffs and craggy steep
slopes, at the bottom of which lies the basin of the Lago Ritom,
in shape something like a shortish straight sausage. The part
occupied by water is rather more than two thousand yards in
length, and on an average about a quarter of the width;* the upper
end, now a grassy meadow traversed by streams, is rather less than
a thousand yards long. The basin is bounded on the southern side
by a range of gneiss—forming here the northern boundary of the
Val Bedretto—which descends with moderate steepness to the lake,
and slightly indents the margin of the latter with the openings
of its shallow valleys. Steep grass slopes and crags of micaceous
schist, becoming more precipitous towards the north, form the head
of the basin, and a line of crags, at about the same elevation,
extends nearly to the lower end of the delta, where they are merged
in the steep slope. The basin, indeed, is bounded on all the
northern side by steep grass slopes and high cliffs, outposts of the
central range of the Lepontine Alps. The part visible from below
consists of the dark micaceous schists,? already mentioned. The
lake-basin, in fact, lies obliquely across the zone of these rocks; its
upper end being not far from their northern boundary, its lower
just at the southern limit. As this is approached, the slopes con-
tinue steep ; the schists pass away across a range towards the lower
end of the Val Canaria; the lowest part of the crest, where also
some rauchwacke occurs, lying between the Pian Alto (7,428 feet)
and Fongio (7,257 feet), perhaps four or five hundred feet below
the latter. This mountain is chiefly composed of gneiss, and is in
reality a prolongation of the gneissic range which, as already
mentioned, forms the southern bank of the Lago Ritom. There the
valley in which that lake lies makes at this point a sharp turn to
the south, and the water is discharged through a very narrow glen
—a mere gateway in the mountains; for within a few yards of the
foot of the lake the stream leaps down towards the Val Bedretto
in a grand series of cascades. This is practically unbroken
for some hundreds of feet, since the craggy slope is extremely steep
to below the hamlet of La Valle. At the above-named gateway, close
to the Hotel Piora, rock can be seen on either side of the stream,
obviously forming its bed. A glance at the mountains on either
side shows the existence of any other outlet to be impossible. So
the Lago Ritom must occupy a true lake-basin, and that a fairly
deep one.
1 Professor Forel has kindly informed me that it is 2,000 métres long, 500 métres
wide, and 60 métres in greatest depth. I am indebted to him for the measurements
of Lago Cadagno and Tom.
2 They belong to the group which for purposes of reference I have called the
Upper Schist. They are described, as well as the geology of the Val Piora, in the
Quart. Journ. Geol. Soc., xlvi (1890), p. 199, ete.
Professor T. G. Bonney—Lake-basins in the Alps. 19
Putting aside for the moment some questions which arise from
the physiography of its borders, I pass on now to a fourth like
situated on the northern flank of the Lago Ritom, at a considerably
higher level. This flank, as I said, rises in cliffs and steep grass
slopes. A path up the latter, near the side of a cascading stream, brings
us into a small upland valley, and we presently reach a lake at its
head called the Lago Tom (6,637 feet). Like the Lago Cadagno,
it occupies a kind of cirque,’ and lies in the strike of the same
rocks, for the enclosing crags consist of similar amphibolitic and
granatiferous gneiss, and at the lower end is rauchwacke, which
can be traced from the southern side of the basin of the Lago
Cadagno across the intermediate spur. ‘But the Lago Tom is not
only on a rock-basin but also on a very remarkable one. The lower
end is dammed by a mass of rauchwacke, in shape something like
a rude causeway. Its top, as a rule, is not less than 12 to 15 feet
above the water, but in one place it is cut by a dry gully two
to three yards wide. Still, the bottom of this cannot be less than
six feet above the level of the water. Rather to the east of this
gap a curving channel or inlet from the lake pierces into the barrier
for some distance. Its sides are cliffs, which at its head are three
or four yards high. Just on the other side of the barrier, a fairly
copious stream breaks out in a shallow glen which continues the
line of the dry gully already mentioned. This unquestionably
drains the lake, but where it starts is not easily ascertained.* There
is no distinct flow up the inlet already mentioned,*® and yet the
stream, within a few feet of its issuing from the rock (a bank of
old snow concealed the actual outlet), is a yard or more wide and
a few inches deep, running with a brisk current. I suppose, there-
fore, that the rocky bed of this inlet is traversed by a number of
small fissures,’ through which the water percolates, to be collected
and carried off by the stream. The rauchwacke (the usual cream-
coloured, rather soft, and broken-looking limestone) is exposed in so
many parts of the barrier that the existence of a drift-blocked
channel seems to me an impossibility, and the Lago Tom must occupy
a true rock-basin.
Three out of these four lakes are situated within cirques or
very precipitous corries, and if we suppose the main outlines of
these to be anterior to the Glacial Age, the ice, as it descended from
the ranges above, would impinge on the level floor, on which under
these circumstances it might have some erosive force. The origin
of the largest lake (Ritom) is less easily explained, unless we
suppose that in all other respects the physical features of the
neighbourhood remain practically as they were when it began to
1 Tts area is given as 1,000 square métres, and it is said to be shallow. But
I should think it would not be less than some 20 feet deep, and might be more.
2 The only sign of disturbance in the lake itself, several yards away from the ~
shore, was clearly an upward flow, i.e. was produced by a strong spring in the bed
of the lake.
3 I twice examined the surface of the water; on the second occasion (a very still
day) I thought I detected a slight movement in some scum on the water.
+ Rauchwacke often has a shattered, almost rubbly aspect.
20 Professor T. G. Bonney—Lake-basins in the Alps.
be formed. The Val Piora, as I have said, consists of a lower step
(the Lago Ritom) and an upper step, with which the Lago Cadagno
is connected. These are separated by a rocky slope, precipitous
in places, nearly 300 feet high. Supposing a glacier to be descending
the Piora valley, we must assume this wall to be already in existence,
or it could not acquire any plunging force, and even then the fall
seems hardly adequate to produce the erosion of a basin like that
of Lake Ritom. Possibly, however, the ice, just at this part,
may have been “jammed”; for the main glacier was probably
augmented by another ice-stream, which descended a shallow, but
fairly well-marked valley, leading from a gneissic peak lying
south-east down to the corresponding corner at the head of the
Ritom basin; while the narrow “gate” by which the water is
now discharged towards the Val Bedretto would block the mass
of ice above it, and this would produce more than usual friction
on the bed of the valley now occupied by the lake and its delta.
This basin, then, the part which les below the present contour-
line of 6,000 feet (in round numbers), is the utmost that, in my
opinion, can possibly be attributed to the erosive action of ice.
Of this action, all the other dominant features in the surrounding
scenery exhibit nothing more than superficial traces, and they
appear to be due to the usual meteoric agencies.
The broad outlines of the Val Piora must have been determined
at an early date. It lies, as I have said, in an infold of schists,
belonging to the upper part of the crystalline series, and of
some rauchwacke of Triassic age, which, after crossing the lower
end of the Val Canaria, reaches the floor of the Val Bedretto at
and near Airolo. Regarding this simply as a fold (it is really
a complicated and faulted one), the natural line for the discharge
of its drainage would be towards the Val Bedretto, in the direction
of Airolo, passing over the col mentioned above as lying to the
north of Fongio. The top of this col is probably about 6,800 feet
above the sea. Fongio itself is clearly a prolongation of the gneissic
range between the Val Piora and the Val Bedretto. Hence, at
some very early date, differential movements in the mountain mass
must have diverted the drainage of the Val Piora from a western
direction to its present outlet on the east side of Fongio, through
some chance dip already existing in the range. Owing to the rapid
descent to the north a groove would soon be formed, and the
direction of discharge finally determined. Since then, as I suppose,
all of the lower, half of the Val Piora that lies below the contour-
line of 6,800 feet (in round numbers), with some of the upper,
must have been excavated. Somewhat beneath this level, perhaps
at about 6,500 feet, a rather marked increase of steepness is often
perceptible in the slopes on the northern side of the lower part of
the Piora valley. Besides this, a structure which is conspicuous
in the Val Bedretto itself may not be without significance. Looking
up that valley from such a point as the top of Fongio, one perceives
that the slopes become near a certain part very much steeper, and
begin to descend from that level rather abruptly towards the bed of
Jukes-Browne & Milne—Oretaceous Fossils in Aberdeenshire. 21
the valley. On the. right bank of the Val Bedretto we can trace
this terrace-like configuration for a long way below the opening
of the Val Piora, and opposite to that gap I estimated its height as
much the same as that of the pass north of Fongio, i.e. not far from
6,700 feet. On the left bank, it will be remembered that, at the
opening of the Val Tremola, the slope markedly changes, perhaps
a thousand feet lower down.? I have observed this structure in
many of the uppermost portions of the Alpine valleys, often some
couple of thousand feet, perhaps occasionally rather more, above
the present floor. It must indicate some very marked change in
the erosive agents, probably an increase in the velocity of the
torrents, since the valley becomes much.more steep-sided. Can it
possibly indicate the results of the Pre-Pliocene set of disturbances ?
But this is venturing into the realm of speculation; my present
purpose is to show that, although doubtless many tarns and lakelets
have no real claim to be called occupants of rock-basins, a few such
do really exist.*
V.— On rHe Cretaceous Fossins FounpD at Morgszxat,
ABERDEENSHIRE.’
By A. J. Juxes-Browne and Joun MItne.
1. Generat Report py Mr. Joun Mine.
ORESEAT is in the parish of Cruden, in the east of Aberdeen-
shire. It lies at an elevation of 300 feet above sea-level, and
the surface of the ground slopes to the sea at Cruden Bay, distant
five miles to the- south. On the north the ground rises gradually,
reaching the height of 450 feet above sea in Torhendry Ridge,
which is strewn with chalk-flints in great abundance.
Previous Investigations.—Geologists are indebted to Dr. William
Ferguson, of Kinmundy, for the earliest notices of Greensand at
Moreseat. In 1839 an excavation 14 feet deep was made for the
water-wheel of a mill, and a drain away from it, on the south side
of the farm steading, a little below the 300-feet level. The
excavation was made in clay, and in it were found layers of sand-
stone containing many fossils. The Rev. J. Johnstone, Belhelvie,
who lived at Moreseat at the time, says that the discovery excited
great interest, and that Moreseat was visited by scientific men,
amongst others by Professor Knight, of Marischal College and
University, Aberdeen, who communicated with Dr. Thomson, of
Glasgow University, on the subject, and informed his class
1 The slope, above Fiesso, begins of course just below the Lago Tremorgio, or
nearly at 6,000 feet.
2 No doubt this has been subsequently cut down below the original level, the
valley being a large one; the Val Canaria has been cut yet lower.
8 IT believe I know of others than those mentioned in this paper, but, as I have
not examined them since Mr. Marr’s paper was published, will not refer to them.
4 Report of the Committee, consisting of T. F. Jamieson (Chairman), A. J.
Jukes-Browne, and John Milne (Secretary), appointed to ascertain the Age and
Relation of the Rocks in which Secondary Fossils have been found near Moreseat,
Aberdeenshire.
22 Messrs. Jukes-Browne and Mine—
of 1839-40 that Greensand had been discovered at Moreseat.
Dr. Ferguson was a student in this class, and thus had his attention
directed to the Moreseat fossils from the first. Hundreds of loads
of clay were removed from the excavation, and many fossils were
collected; but when the wheel was put in and built up, and the
drain was covered up, there remained no trace of the interesting
discovery.
In 1849, on making a deep ditch alongside a road to the north
of the farm steading, and a little above the 300-feet level, the same
clay, sandstone, and fossils were met with. Dr. Ferguson sent
a notice to the Philosophical Society of Glasgow.’ Next year
he visited the newly-made ditch, and sent an account of the original |
discovery and a description of what he saw to the Philosophical
Magazine.” Dr. Ferguson’s description of what he saw is quoted
here, because it exactly coincides with what was seen in subsequent
excavations. ‘An excavation about 7 feet in depth was made,
and the section presented irregular layers of unctuous clay, of
a dark-brown colour and soapy feel, and so tough and adhesive
as to render it a work of considerable labour to dig it out. Inter-
stratified with this clay were thin layers of a compact sandstone.
These layers of sandstone were not continuous; they graduated
into each other, thinned out, disappeared, and reappeared most
confusedly. They were very much inclined, dipping towards
the south. The whole mass had much the appearance of having
been drifted; although from the nature of the matrix, and the state
of preservation in which the shells are found, it does not appear
as if it could have been drifted far. The sandstone is tough and
soft when newly dug, but hardens on exposure to the air and
becomes light-coloured in drying. When wet, it presents a mottled
appearance, the colour being greenish; when dry, this almost
disappears.”
In 1856 a collection of fossils from Moreseat made by Dr.
Ferguson was examined by Mr. J. W. Salter and Mr. W. H. Baily.
An account of them was published next year in the Quarterly
Journal of the Society, along with a note by Dr. Ferguson.
Mr. Salter regarded the Moreseat fossils as an indication, in the
near neighbourhood, of Upper Greensand in sitd. ‘Types of these
fossils are preserved in the Museum of Practical Geology, Jermyn
Street, London. 7
In the memoir descriptive of the sheet of the Geological Survey
containing Moreseat, notice is taken of the Greensand fossils found
there, and of the Chalk-flint fossils found at Bogingarrie, a few
miles to the south-west, also described by Mr. Salter; but the
surveyor does not say that he saw at Moreseat any fossils or
fragments of Greensand sandstone.
In 1894 the Secretary of the Committee was lecturing at Cruden
on Geology and Agriculture for the Aberdeen County Council, and
was induced by the mention of Greensand in the memoir to visit
1 See Proceedings of the Society, vol. iii, 1849.
2 See vol. xxxvii, 1880.
Cretaceous Fossils found in Aberdeenshire. 23
Moreseat and make inquiries; but he could learn nothing further
than that fossils had been found in the excavation made for the
mill-wheel, and as it was enclosed with masonry nothing could
be seen. He visited the place repeatedly and examined all the
ditches and watercourses on the farm, but found no fossils. The
reason of this was seen afterwards. When pieces of the sandstone
were exposed to frost they became a soft paste on thawing, and
all trace of the fossils they contained disappeared.
He afterwards met with Mr. Alexander Insch, Peterhead, who
had heard that fossils had been found north of the farm steading.
Accompanied by him and Mr. D. J. Mitchell, Blackhills, Peterhead,
he again visited Moreseat. An excavatiqgn was made to the north
of the ditch seen by Dr. Ferguson, and after passing through a foot
or eighteen inches of sandy ‘clay, thin layers of sandstone with
fossils were found. The appearance of the layers of sandstone
was peculiar. They conveyed the idea that they were cakes of some
plastic material spread out in a soft state, yet not wet enough to
bear great lateral extension without cracking. The layers were
full of vertical cracks, which broke them up into small fragments.
These might have been caused by shrinking on drying, as the
excavation was made where the ground would be dry in summer.
The method of occurrence was the same as that described by
Dr. Ferguson already quoted. The fossils found were chiefly casts
of shells.
Specimens were forwarded to the British Association with an
application for a grant of money to ascertain by deeper excavation
whether the bed from which the sandstone had come could be found
there. Though the application was unsuccessful, digging was con-
tinued by Messrs. Mitchell and Insch, who collected a large quantity
of fossils in various places over an area a quarter of a mile broad
in the neighbourhood of Moreseat.
In 1895 specimens were sent to Dr. H. Woodward, of the British
Museum (Natural History), London, with another application for
a grant from the British Association. A grant of £10 was given,
and the Committee already named was appointed.
Professor J. W. Judd, of the Royal College of Science, South
Kensington, was consulted about the specimens already collected
by Messrs. Mitchell and Insch, and by his advice they were sent
to the Geological Survey Office, where they were examined and
compared with Dr. Ferguson’s typical specimens by Mr. G. Sharman
and Mr. HE. T. Newton. They published a statement of the result
in the Guonocgicat Magazinu, Dec. IV, Vol. Ill, 1896, p. 247.
They came to the conclusion that the specimens had “been derived
from beds where a large part of the Cretaceous series of strata
occurs; not only Upper and Lower Chalk and Upper Greensand,
as pointed out by Salter, but also beds of Lower Greensand or
Speeton Clay age.” In making this statement they seem to have
referred not only to the specimens collected by Messrs. Mitchell and
Insch, but also to the Chalk-flint specimens in the Ferguson
collection. It may therefore be noted that though flints are fouud
24 Messrs. Jukes-Browne and Mine—
in great abundance on the ridge above Moreseat, they become fewer
in going down the hillside, and are comparatively scarce at
Moreseat, and it may be assumed that none of the flint-fossils
in the Ferguson collection were found in the immediate neighbour-
hood of the Greensand fossils.
Work of the Committee.—On being made aware of their appoint-
ment the Chairman and the Secretary met on the ground,
accompanied by Messrs. Mitchell and Insch. Mr. Johnstone, the
proprietor of the farm, kindly consented to allow an excavation
to be made. All the places where fossils had been found were
examined, and it was resolved to sink a shaft at the highest
place where they were certainly known to be, in the belief that
the fragments of sandstone had been moved from a higher to
a lower level. The place selected is on a knoll north of Moreseat,
about 330 feet above the sea-level, and about a quarter of a mile
from the place where fossils were found in 1839. The ground
to the north is covered with peat-moss overgrown with heather, and
nothing can be seen of its character. Half a mile to the north-east
there is some cultivated land, and a pit had been sunk by a crofter
for a pump in white unstratified siliceous matter, apparently detritus
of chalk-flints. To the north-west another pit had been dug. At
first glacial drift clay was met with, then fine stratified sand,
unsuitable for a pump well, and the excavation was stopped at
14 feet deep. This hole was 50 feet above the site selected for
the shaft. It was thought best to defer the sinking of the
shaft till the following summer to avoid risk of obstruction from
water.
Mr. J. T. Tocher, the Secretary of the Buchan Field Club,
which is affiliated to the British Association, undertook to contract
for the work, and along with Mr. Mitchell to visit it while in
progress, and to examine the material excavated.
The shaft was dug in the summer of 1896, and a depth of
30 feet was attained. The first foot consisted of ordinary soil.
Below it was found a yellowish-brown sandy clay mixed with small
fragments of sandstone and pebbles of quartzite and flint. The
sandstone was afterwards found to contain Glauconite, and may
be termed Glauconitic Sandstone. Almost every fragment yielded
fossils, mostly casts of small shells. At 3 feet the clay became
finer and the sandstone fragments more abundant. At 4 feet they
were in layers among the clay, gradually thinning out and
disappearing, as described by Dr. Ferguson. At 5 feet, on the
south side of the shaft, a deposit of fine white sand was found,
in which were pebbles of granite, quartzite, and flint. In the
other part of the shaft the clay continued, with numerous bits
of the grey glauconitic sandstone in a layer, much broken, dipping
to the south, which is the direction of the slope of the surface of
the ground at Moreseat. The mass of sand increased down to
8 feet, where it ended. At the bottom of the sand there was
a block of granite a foot in diameter, and under it a large flint
pebble. At 10 feet there was, on one side, a mass of black clay
Cretaceous Fossils found in Aberdeenshire. 25
with a soapy feel, in which sandstone fragments, much worn,
were found. This black clay stopped at 11 feet. At 14 feet it
began to appear again, and to take the place of the yellowish-
brown clay, which ended at 16 feet. The lower part of it
contained many stones. From this level the black clay continued
all the way down to 80 feet, where it was succeeded by red
laminated clay, without stones of any kind. The black clay con-
tained large stones of granite and quartzite and small fragments
of the glauconitic sandstone all the way, but the stones grew fewer
in number the deeper the shaft was sunk, and the sandstone
fragments had almost ceased at 27 feet. The excavation could
not be carried farther than 80 feet, because, on reaching the red
laminated clay, water began to come in and the funds were
exhausted. .
The Committee regret that they were unable to ascertain the
nature of the solid rock under the shaft. Most likely it would
have been found to be granite, the rock seen at the sea-coast
from Cruden Bay to Peterhead. The shaft was evidently in glacial
drift clay all the way, and therefore the sandstone fragments were
not in sitt, but had been transported, apparently from the north.
By a series of pits a few feet deep made in this direction it might be
possible to follow the sandstone farther up the hill, and a shaft sunk
at the uppermost place where they could be found might discover
the bed from which they came; yet the Committee cannot venture
to express a confident opinion that another excavation would be
more successful than the last in finding the origin of the Glauconitic
Sandstone. Many appearances indicate that the latest changes
on the surface of the ground in the district in which Moreseat
is situated were caused by local glacial sheets, perhaps not on
a great scale, yet capable of moving great quantities of loose and
soft matter. The white sand in the shaft seemed to have been
moved bodily from a bed seen to the north-west at a higher level.
The original seat of the Glauconitic Sandstone may have been to
the north of the shaft, a little farther up the hill, and yet the
bed may have been entirely removed by ice descending the hill.
If, however, the British Association renew the grant, the Committee
will be happy to make another attempt to find the origin of the
Moreseat fossils.
Mr. Tocher, F.I.C., analyzed the clays found in the shaft, and
ascertained that the reddish colour of the one was due to ferric
oxide of iron, and the black colour of the other to ferrous oxide.
Mr. Insch collected a large quantity of sandstone fragments
containing fossils. These were examined by Mr. A. J. Jukes-
Browne, and will ultimately be deposited either in the Aberdeen
University Museum or in that at Peterhead.
2. Report on tHe Fossins sy A. J. JuKES-Browne, B.A., F.G.S.
The existence of Cretaceous fossils, embedded in a kind of
‘*Greensand,” and found at Moreseat, near Aberdeen, has been
known to geologists for nearly fifty years. Mr. W. Ferguson
26 Messrs. J Pie MBG and Milne—
discussed them in a paper read before the Philosophical Society
of Glasgow in 1849, and subsequently communicated to the
Philosophical Magazine." In this he observes that most of
the remains are casts, and he mentions the occurrence of several
species of Ammonites and Belemnites, as also of Cardium, Terebratula,
Trochus, Solarium, Cerithium, and Spatangus.
Some of Mr. Ferguson’s fossils were examined and named by
Mr. J. W. Salter in 1857,? who gave a list of fourteen species, two
of them being Ammonites doubtfully referred to—Am. Selliguinus,
Brong., and Am. Pailletianus, D’Orb. Four of the others he
describes as new species, and from the remaining six he comes
to the conclusion that the fauna is of Upper Greensand age.
From 1857 to 1896 no further light was thrown on the subject,
but in the latter year some of the fossils collected by Messrs.
Mitchell and Insch were submitted to Messrs. Sharman and Newton,
who made a careful examination of them, and communicated the
results to the GeoroGicaL Magazine. They compared these fossils
with the specimens described by Salter, which are preserved in the
Museum of Practical Geology, and found the matrix to be the same.
They also state that though slight differences are noticeable in
different pieces of the rock, yet all the samples are “so similar
that one can scarcely question their having been originally derived
from the same bed.”
They found, however, that many of the fossils could not be
identified with any Upper Greensand species, but were Lower
Cretaceous forms, many of them identical with those occurring
in the Speeton Clay. They admitted, however, a few species which
occur in the Upper Cretaceous series only, and have not been found
in any British Lower Cretaceous deposit. Hence they conclude
“that the faunas which in the south mark the distinct horizons
of Lower Greensand, Gault, and Upper Greensand are here in
Aberdeenshire included in one bed of nearly uniform character
throughout.” This conclusion certainly invested the Moreseat
fossils with still greater interest than they possessed before.
A collection of the fossils was sent to me by the Rev. John Milne
in September, 1896, but it was impossible for me to examine them
in time to report on them before the meeting of the British
Association in that year. I have since, however, given them careful
attention, and have received much assistance from Messrs. Sharman
and Newton, whose previous acquaintance with many of the species
has saved me much time and labour.
It is not an easy task to identify these Moreseat fossils, for they
are all in the state of casts and impressions. In no case does
any actual shell or test remain, but the firmness of the rock has
in most cases prevented the enveloping matrix from being pressed
down on to the internal cast, so that the external cover generally
retains the shape and impression of the original shell, and a mould
! Phil. Mag., vol. xxvii, p. 430 (1850).
? Quart. Journ. Geol. Soc., vol. xiii, 1857, p. 83.
3 Gzou. Mae., Dec. IV, Vol.-III, 1896, p. 247.
Cretaceous Fossils found in Aberdeenshire. 27
can, if necessary, be taken from it. The fossils had been carefully
collected, and as both casts and covers had been transmitted, it has
been possible to determine many of the species.
_ Before discussing the species, however, the rock itself merits
description, for its peculiar characters seem to have escaped previous
observers. To the eye it presents itself as a very fine-grained
siliceous rock, resembling malmstone, dark grey when damp and
freshly broken, drying to a lighter grey. Fractured surfaces often
show spots and patches of darker material than the rest of the mass.
Under the lens it showed a finely granular matrix, containing many
small grains of glauconite and numerous flakes of mica, with small
patches of a yellowish-green mineral which is apparently a decom-
position product.
The general aspect and light specific gravity of the rock led me
to suspect the presence of colloid silica, and accordingly I sent
specimens to Mr. W. Hill, F.G.S., for microscopical examination.
Mr. Hill cut slices from two of these, and furnishes me with the
following account of the structure exhibited by them :— “The
material of both slides is alike, and compares most nearly with the
micaceous sandstone of Devizes (Upper Greensand). The ground-
mass consists of amorphous and semi-granular silica, neutral to
polarized light, with little or no calcite. There are many sponge
spicules, the walls of which have mostly disappeared, but which
are outlined in the matrix. The space once occupied by the spicule
is often partly filled with globules of colloid silica, like those in
malmstone described by Dr. Hinde,’ and similar globules are
dispersed through the mass of rock. There is much quartz sand
in small, angular, even-sized grains, but not so much as in Devizes
sandstone. Glauconite grains are also abundant, but the quantity
varies much in different parts of the rock; the grains seem to
be breaking up, and are often seamed with vein-like markings.
There are also larger patches of dirty-green material, which has
a somewhat indefinite outline, and may be of secondary formation.
Small flakes of mica are scattered through the slides, but it is
only when these are cut transversely that the mineral can be easily
identified.”
‘From the above description it will be seen that the rock may be
termed a gaize—that is, a fine-grained sandstone, in which colloid
silica is an important ingredient ; this is not a common rock, and in
England it is only known as occurring in the Upper Greensanil
in association with malmstone. In France a gaize of Lower Gault
age, containing Ammonites mammillatus and Am. interruptus, occurs
in the Ardennes (Draize), but [ can find no record of the rock
occurring in the Lower Cretaceous series either in France or
Germany.
The formation of gaize and malmstone probably took place in
clear water of a moderate depth; it is not a shallow-water deposit,
and yet it was deposited within the range of a current which carried
? Phil. Trans. Roy. Soc. 1885, pt. ii, p. 403.
28 Messrs. Jukes-Browne and Milne—
fine sand. The abundance of sponge spicules shows that the con-
ditions were such as to favour the growth of siliceous sponges.
Remarks on some of the Fossils.
The collection sent to me includes some species which have not
yet been recorded from the Moreseat rock, and as these are all
Lower Cretaceous forms, the Vectian element in the fauna is clearly
very strong—so strong indeed that I am led to doubt the existence
of some of the Upper Cretaceous species which have been supposed
to occur. I shall therefore offer some remarks on certain species,
and give a complete revised list of the Moreseat fauna, so far as
it is at present known.
Micrabacia coronula, Goldf.—This identification requires confirma-
tion. It depends solely on Salter’s authority, for the specimen
he saw is not in the Jermyn Street Museum, and no other
specimen has been detected in the collections recently made. The
species 1s not known to occur below the Upper Greensand zone of
Pecten asper, and would be difficult to recognize from a cast only.
Echinoconus castanea, Brong.—This also requires confirmation, for
the specimen so named by Mr. Salter has not been found at Jermyn
Street, and no other example has been seen. In England its
earliest appearance is near the top of the Upper Greensand, but
in Switzerland it ranges down to the base of the Gault (see De
Loriol in “ Echinologie Helvétique”’), so that it may in some localities
range even lower. No species of Echinoconus, however, has yet
been recorded from rocks of Lower Cretaceous age.
Discoidea decorata(?), Desor.—This specimen was among those
sent by Mr. Milne. It consists of a nearly perfect external mould
in two parts. It differs from D. subucula in having close-set
rows of nearly even-sized tubercles, eight rows on the inter-
ambulacral areas, four on each set of plates, and four rows on
the ambulacral areas; but the two inner ambulacral rows do not
reach either to the apex or to the peristome. The mouth and vent
are both rather large. In these respects it agrees with D. decorata.
Mr. C. J. A. Meyer having informed me that he possessed
specimens of a Discoidea from the Vectian of Hythe, the Moreseat
Specimen was sent to him for comparison. He reports that it agrees
with those from Hythe, but he is doubtful whether they are
referable to D. decorata, Desor, or D. macropyga, Ag. Both are
Lower Cretaceous species.
Rhynchonella compressa.—The specimen so named by Salter is at
Jermyn Street, and has been examined again by Messrs. Sharman
and Newton, with the result that they think it is only a compressed
variety of Rh. sulcata, Park. As specimens of Rh. sulcata are not
uncommon at Moreseat, and as it is a very variable form, Rh.
compressa may safely be excluded from the list.
Waldheimia faba, D’Orb. (non Sow.).— One specimen apparently
referable to this species is among those sent to me. As it is only
Cretaceous Fossils found in Aberdeenshire. 29
a cast and as the shell is smooth, one cannot be quite sure of the
species, but the shape is well preserved, and I am indebted to
Mr. Meyer for pointing out that it has the squareness towards
the front which is characteristic of the species in question. This
is well shown in the example figured by Davidson (‘Cret. Brach.,”
vol. iv, pl. vi, figs. 12-14), which came from the Speeton Clay
of Knapton in Yorkshire.
Tima semisulcata, Sow.—This species has appeared in previous
lists on the authority of Mr. Salter, but the specimen is in the
Jermyn Street Museum, and Mr. Newton informs me that it is
only an internal cast, and may, with equal probability, be referred to
L. Dupiniana. As specimens of the latter do occur, and none
referable to L. semisulcata have since been found, I think this
Upper Cretaceous species may be omitted from the list.
Arca securis, D’Orb.—I have ventured to enter the common Arca
of the Moreseat sandstone under the name of securis instead of
under carinata, because the specimens I have examined seem to
me to come nearer to securis, and Mr. Meyer, to whom a specimen
was sent, is of the same opinion. The two species are so closely
allied that some paleontologists regard them as identical; but
there are slight differences, and Messrs. Sharman and Newton
agree with me in considering the Moreseat specimens to be smaller
and shallower in the valve than the ordinary A. carinata of the
Upper Greensand ; and in these respects they resemble A. securis.
In some of them, moreover, the ribs on the posterior area are like
those in D’Orbigny’s figure of securis; so that, if the forms are
separable, I think these should be listed as securis.
Leda scapha (?), D’Orb.—I have seen two casts which probably
belong to this species, though they equally resemble L. Marie of
the Gault, for, as Mr. Gardner has remarked, there is very little
difference between these species.
Pectunculus umbonatus, Sow.—This is another of Mr. Salter’s
identifications, and unfortunately it also is only an internal cast.
There are several species of Petunculus to which such a cast
might belong, but the probabilities are against its being P. umbonatus.
As no other specimen has occurred among the fossils recently
collected, it will be best to leave it without a specific name for the
present.
Turbo. Triboleti (2), Pict. and Camp.—There is one specimen,
a portion of the external impression of the shell, showing an
ornamentation closely resembling that of Turbo Triboleti, which
is a species from the Upper Gault of Ste. Croix. This specimen
was sent to Mr. Meyer, who informs me that he has an imperfect
specimen from the Vectian of the Isle of Wight which it equally
resembles.
Ammonites flexisulcatus (?), D’Orb.—A small Ammonite was found
in breaking up a lump of the material sent to me, and was
30 Messrs. Jukes-Browne and Milne—
forwarded, with other specimens, to Messrs. Sharman and Newton.
They reported that it most resembles A. flewisulcatus, though the
portion preserved is smooth and without sulcations. !
Nautilus sp., Sow.—Among the fossils sent to me by Mr. Milne
is the cast of a Nautilus, badly preserved, but showing strong
transverse rugations or ribs like those of N. radiatus, but its
condition is such as to prevent any certainty of identification.
Mr. A. H. Foord has kindly examined the specimen, but could
not venture to name it.
a g Re eS en
Bd | 22 eos| a |e qe s
poe i Om 5 m Bes 229
Be Ge Moreseat Fossils. piel g S BEG ESN
BS |ES aeoiies) |e joc
Actinozoa.
Coral (like Micrabacia)
Echinoderms.
Dp. Ananchytes (? Cardiaster)
Te |) Ws Discoidea decorata, Desor (?) #
p- Kchinocyphus difficilis, Ag. *
p. | M. Enallaster Scoticus, Salter
p- Echinoconus castanea (?) * * *
Annelida,
p- Serpula, sp.
Polyzoa.
p- Entalophora (?)
Brachiopoda.
p- | M. Rhynchonella suleata, Park. * # *
Dp. Terebratula, sp.
M. Terebratella (cast only)
M. Waldheimia faba, D’Orb. (non Sow.) *
Pp. », hippopus var. Tilbyensis, Dav.|
Lamellibranchiata.
M. Anatina, sp.
p. | M. Area securis, D’ Orb. #
p. », Raulini (?), D’Orb. * ?
1S |) ML Astarte striato-costata, Forbes #
p- | M. Avicula simulata, Baily
p- |M.? Cardium Raulinianum, D’Orb. — # x
M. Cardium, sp. (cast only)
106 Corbula, sp.
p. | M. Cyprina Fergusoni, Salter
To |) AWE Exogyra (small species)
D- Gervillia solenoides, Defr. * # #
p- e near to rostrata
p- Goniomya, sp.
p- Tnoceramus, sp.
M. Leda scapha, D’ Orb. *
p- Lima Dupiniana, D’Orb. #
M. », longa (?), Rom. #
D- », near to abrupta, D’ Orb.
p. | M. Limopsis texturata, Salter
p. | M. Lucina, sp.
M. Ostrea frons (?), Park. (carinata, Sow.) | # * *
p- Panopea, sp. |
p- | M. Pecten orbicularis, Sow. 2 Es # *
Dp. Pectunculus, sp.
Cretaceous Fossils found in Aberdeenshire. ol
za |e GoglS Ie ves
28 \s8 oa| & |One| ess
Be]. Moreseat Fossils. 25 8 8 gs 3 ge S
Sisis Oew = S Se
Bo |5° BOOL § se | [Ss
= is}
p: | M. Pinna tetragona, Sow. # * #
[De || WL. Plicatula placunea, Lam. # P)
p- Spondylus, sp.
M. Tellina, sp.
M. Thetis (?)
P- Trigonia Vectiana, Lyc. #
M. Ae sp. Nov. 6
M. Venus Brongniartina (?), Leym. #
Gastropoda.
D- Acteon, sp.
p. | M Cerithiam aculeatum, Forbes MS. *
p-|M Dentalium ccelulatum, Baily
Dp: Phasianella (like ervyna, D’ Orb.)
M. Solarium, sp.
p. | M. Trochus pulcherrimus *
Dp: SDs
eke Turbo Triboleti (?), P. & C. # *
Cephalopoda.
M. Ammonites flexisulcatus (?), D’ Orb. %
p. | M. i Mortilleti, P. & Lor. x
p. | M. 99 Speetonensis (var.) %
Dp: 55 Selliguinus (?), Brong. *
Pp: Belemnites, sp.
Pp: Crioceras Duvallii, Lév. #
M. Nautilus, like radiatus, Sow. o-
It only remains to indicate the conclusion to which the study of
the Moreseat fossils has led me. .
Of the species enumerated by Mr. Salter in 1857 four have been
omitted from the preceding list, being regarded as doubtful identifi-
cations which have not been confirmed by subsequent discoveries.
Of the three genera of Echinoderms mentioned by him the
Discoidea was probably the species which resembles D. decoraita,
and the two named respectively Diadema and Ananchytes may have
been Lower Greensand forms for anything that we know to the
contrary.
The number of named species available for comparison with other
faunas is now 33. Out of this total no fewer than 25 are species
of Lower Cretaceous age, and only 7 of these range into the Gault ;
5 are species which have not been found elsewhere, 2 are Upper
Greensand species, but one of these is a doubtful determination,
and 2 are Ammonites, of which the identification is also doubtful.
There is therefore an overwhelming proportion of exclusively Lower
Cretaceous species, namely 18 to 2, while out of the 6 Cephalopods
5 are exclusively Lower Cretaceous forms, the only one which is not
being the very doubtful 4m. Selliguinus.
The occurrence of one Upper Greensand HEchinoderm (Hchino-
cyphus difficilis), and the possible occurrence of another ranging
o2 Professor Spencer— Continental Elevation.
from Lower Gault to Chalk (Hchinoconus castanea?), is hardly
sufficient evidence to warrant the conclusion that a part of the
rock-mass was of Upper Greensand age. There is nothing except
the Am. Selliguinus that is specially characteristic of the Gault,
and the question is this: What is the evidential value of the
occurrence of Hchinocyphus difficilis, and possibly also of Hchinoconius
castanea (?)? I think it may be answered in this way: it is more
reasonable to suppose that these two species, or forms very closely
allied to them, date really from Lower Cretaceous times, than it is to
suppose the deposition of exactly the same kind of rock material
should have continued at any one place from the time of the
Lower Greensand to that of the Upper Greensand. In other
words, I believe that the rock-mass from which the Moreseat fossils
have been derived was entirely a Lower Cretaceous rock, but high
in that series, and corresponding approximately to the Aptien stage
of France, and to the Lower Greensand or Vectian of the Isle of
Wight.
VI.—Ow tHe ContTiInenTAL ELEVATION OF THE GLACIAL PERIOD.
By Prof. J. W. Spencer, M.A., Ph.D., B.Sc., F.G.8.
ConrTENTs:
Introduction.—Character of the Submarine Antillean Valleys.—Gradients of Sub-
marine Valleys.—Date of the Continental Elevation.—Migration of Mammals.— ©
Submarine Channels off the Eastern Coast of America.—Submerged Plateau of
the North Atlantic.—Continental Elevation a Cause for Glacial Climate.
Introduction.
EFORE the last meeting of the British Association, held in
Liverpool, Professor Edward Hull presented a paper upon
“Another Possible Cause of the Glacial Epoch.” In that paper,
Professor Hull applied the writer’s work on the ‘ Reconstruction
of the Antillean Continent,”? which brought together evidence of
great continental elevation. This elevation and its effects upon the
ocean-currents, in diverting them from the West Indian regions,
with the consequent reduction of their temperature as they reach
the northern latitudes in conjunction with the elevation of the land,
were thought by Professor Hull to be sufficient causes for the
production of the glacial climate over temperate regions in late
geological times. The writer has hitherto never applied his
observations on high continental elevation to climatic changes ;
but in this paper he proposes to extend briefly his researches
from the Antillean region to the higher latitudes of America
and the North Atlantic regions. Something has also been learned
of the date of the great elevation; consequently inferences may be
drawn as to climatic changes.
Character of the Submarine Antillean Valleys.
The feature of the paper on the “ Reconstruction of the Antillean
Continents,” and subsequent observations of the region, show that —
1 J. W. Spencer, ‘‘ Reconstruction of the Antillean Continent’’ : Bull. Geol. Soc.
Amer., vol. vi, pp. 103-140, 1894.
Professor Spencer—Continental Elevation. I)
there are deep valleys, often of great length, extending from the
mouths of the existing rivers, and crossing the American coastal
plains, over deeply-buried channels. These are plainly recognizable
in soundings upon the submarine coastal plateaux, and amongst the
banks and islands of the neighbouring West Indian seas, to depths
of 12,000 feet or more, before reaching the oceanic floors. The
drowned valleys radiate from the continental margins and extend in
a direction across that of the coast, and the mountain ranges to the
back of it. Their courses do not usually coincide with those of the
mountain folds. These submarine valleys are often recognizable for
hundreds of miles in descending to the floors of the ocean-basins, as
may be seen amongst the Bahamas. Frequently the divides between
different systems are themselves submerged, as in the Straits of
Florida. The submerged valleys are no broader than those of
existing rivers, such as those of the Amazon and the St. Lawrence,
nor indeed are they usually as wide. The Colorado canon, from five
to twelve miles across, between walls of 2,000 feet in height, is wider
than some of the drowned valleys, which in part are canon-like.
Both the submarine plateaux and the floors of the valleys are like
comparatively level plains or base-levels of erosion, which represent
pauses when the streams and atmospheric agents could not further
deepen their valleys, but only broaden them out into plains, until
a subsequent elevation of the region permitted the streams once
again to deepen their channels.
Gradients of Submarine Valleys.
The gradients of the submerged valleys (except along the reaches
crossing extensive plains, now below sea-level) can only be com-
pared with those of plateau regions, and not with the slopes of such
a river as the Mississippi, which flows over great plains at low
elevation. The manner in which the valleys descend from one
platform to another is illustrated in the plateau region of Mexico
and the West. An example of the declivity of such valleys may
be seen along the Mexican Railway, back of Vera Cruz, and another
above Monterey. The land valleys are made up of a series of steps
with greater declivities between them than occur between those
submerged. The various platforms represent the rise of the land
during the excavation of the valleys. The gradients of the sub-
merged plateaux are frequently as small as, or smaller than, those of
such plains as the Mississippi, while the declivities at their margins
are less abrupt than those of the land valleys descending from
tablelands, as may be seen by comparing them with the Mexican
valley sections. The gradient of the Colorado river, in its canon
3,000 feet deep, is greater than that of the submerged platforms.
Besides the greater valleys, descending from the high plateaux,
there are many short tributaries, heading in amphitheatres, -where
the slopes may be from 200 to 600 feet per mile; the whole
resembling gigantic “‘ wash-outs.” So also similar short drowned
valleys occur on the edges of the submarine plateaux. The data
concerning these comparative declivities were not obtained when the
DECADE IV.—YOL. V.—NO. I. 3
34 Professor Spencer—Continental Elevation.
original paper upon the submarine river-like valleys was prepared,
but they now greatly strengthen the inferences that the drowned
plateaux may be used as “ yardsticks” for measuring the amount
of late continental elevation.
In his paper referred to, Professor Hull endorses the correctness
of the interpretation that the submerged valleys were formed by
atmospheric agents. Such inferences being correct, the West Indies
formed a high continental plateau, while the Gulf of Mexico and
the Caribbean Sea were plains or inland lakes draining into the
Pacific Ocean across what are now low passes of Mexico and Central
America.
Date of the Continental Elevation.
Elsewhere the writer has shown! that the old Mio-Pliocene
surfaces extended much beyond their present limits, and were
subjected to long-continued reduction to base-levels of erosion.
Upon the undulations of the country then produced, the Lafayette
deposits of the continent form an extensive mantle, which has been
provisionally considered as belonging to the late Pliocene epoch.
The surfaces are enormously denuded. Following this formation
northward, although there are but few exposures of contact, the
writer has observed near Somerville, N.J., the Lafayette overlain
by a few feet of glacial drift, which has been extensively denuded,
as it is locally wanting. Resting upon the boulder drift, and where ~
this has been removed, upon the underlying Lafayette loams and
gravels, the Columbia formation may be seen. This feature shows
that the epoch of glacial deposits occurred between the Lafayette
and Columbia periods. Consequently, the epoch of great elevation,
which favoured the excavation of the valleys, coincided with that
of the glacial deposits of the early Pleistocene days.
Migration of Mammals.
The Antillean Continent formed a bridge connecting North and
South America, over which only a few mammalian remains have
been found, as the greater portion of it is now beneath the sea. At
Port Kennedy, Pennsylvania, an extensive fauna has been discovered
in fissures, and upon it Professor Edward D. Cope was engaged at
the time of his recent death, but some results he had made known.
Of 38 species of mammals, so far determined, a large percentage are
extinct, and among these occur Hquus and Megalonyx. ‘There is
also an abundance of remains of an old form of South American
bear, which are not known to have crossed the plains of the West.
The occurrence of these types at Port Kennedy, Professor Cope
regarded as strongly supporting the theory of the Antillean bridge
in the early Pleistocene epoch. There is also a newer cave-fauna in
Eastern North America, which belonged to a later period, separated
from the first by a partial submergence, according to the conclusions
of that distinguished author. Hlephas has recently been found in-
Guadeloupe.
1 «Reconstruction of the Antillean Continent,’’ cited before.
Professor Spencer—Continental Elevation. 35
Submarine Channels off the Eastern Coast of America.
The submerged valleys, which are best developed among the
Bahamas and off the adjacent portions of the continent, provide the
key for interpreting the submarine features of other regions. The
broad subcoastal plain off the south-eastern States becomes narrowed
to a few miles east of Cape Hatteras; but northward it broadens
again, and eventually reaches a width of nearly 300 miles south-east
of New England, and more than that across the submarine plateau
which forms the Newfoundland banks. East of Labrador it has
a considerable breadth, but the soundings there are too scanty for its
delineation. In drawing the contours at a considerable distance
apart, the same forms of indentation are repeated in the borders of
the plateau as those observed farther south; but where the contours
are drawn close together (even where the soundings are not as
numerous as is desirable), the deep valleys are found to be con-
tinuations of existing rivers. Thus, Lindenkohl! traces the Hudson
River channel to a depth of 2,852 feet, and the Great Egg Harbour
channel to 2,334 feet, where the plateau is submerged only 600 feet.
The Delaware and the Susquehanna valleys are also recognizable on
the subcoastal plain to depths of about 3,000 feet.
In 1889, the writer showed how the Laurentian valley was
submerged for a distance of 800 miles, beneath the waters of the
Gulf of St. Lawrence, with the channel from 1,200 to 1,800 feet
below the surface of the sea; but near the edge of the drowned
plateau it descends abruptly to a depth of 3,666 feet.2 The same is
true of the valleys crossing the New England, Nova Scotia, and the
Newfoundland banks. From the edge of the continental shelf, the
Susquehanna valley descends precipitously to a depth of more than
9,000 feet, with its valley recognizable to 12,000 feet. The Delaware
descends abruptly to 6,066 feet, and is plainly traceable to 11,256 feet,
and to greater depths beyond. The same is true of the Hudson and
its tributaries from Connecticut, being recognizable to depths of
more than 12,000 feet. From the borders of Massachusetts, Nova
Scotia, and the Newfoundland banks the valleys descend pre-
cipitously into amphitheatres 6,000 or 7,000 feet below the surface,
and continue to depths of 12,000 feet, and in some cases to even
15,000 feet.
While to an unknown extent the drowned plateaux are covered
with Tertiary formations, still the submerged valleys must, to
a considerable extent, have been excavated out of hard Paleozoic
and older strata, thus producing variations in the lengths of the
deeper channels, and forming a contrast with some of those of the
Antillean region.
From analogy with land valleys, the channels crossing the sub-
marine coastal plains of a few hundred feet, afterwards of perhaps
3,900 feet, represent a long period of elevation. Then followed the
1 American Journal of Science, vol. xli, p. 490, 1891.
2 J.W. Spencer, ‘‘ High Continental Elevation preceding the Pleistocene Period’? :
Bull. Geol. Soc. Amer., vol. i, p. 6, 1889.
36 Professor Spencer— Continental Elevation.
great elevation of perhaps two miles or more in height, continuing
only long enough to allow the streams to dissect the margins of the
tablelands, and form amphitheatres belonging to the new base-level
of erosion. While the great depressions shown in the soundings
may have in part been occasioned by an exaggerated oceanic sub-
sidence along the line of the continental margin, yet amongst the
West Indies it has been found that the actual depression has exceeded
two miles. Although the deeper valleys of the north may be less than
a hundred miles in length, their slopes are no greater than those of
the valleys descending from the Mexican plateaux.
From the generalization of facts just given, the conclusion is, that
the high continental elevation of the Antillean region extended
northward in Hastern America, of which supporting data have been
collected as far as Labrador.
Submerged Plateau of the North Atlantic.
If the analytical methods which have revealed the drowned
valleys of the American coast be applied to the well-known North
Atlantic plateau, similar valley-like phenomena will be discovered.
While there are numerous soundings across the Atlantic, in the
region of latitude 52°, the lines of soundings to the north are too
far apart to everywhere afford detailed study of the submarine
features; except that they show an extensive submerged plateau
(from 7,000 to 9,000 feet) rising northward to the Iceland ridge,
beyond which it again descends rapidly to depths of 12,000 feet,
and west of Spitzbergen, 15,900 feet. The summit of the plateau,
between Greenland and Norway, is submerged scarcely more than
1,200 feet. However, across the summit there are deeper channels,
from the cols of which, valleys trend in opposite directions, like
those amongst the West Indies or in the Straits of Florida. These
cols are now submerged: that between Greenland and Iceland, to
1,974 feet; between Iceland and Faroe, 1,814 feet; between Faroe
and Shetland, somewhat more than 3,000 feet ; and between Shetland
and Norway, about 1,000 feet. The southern margin of this plateau
(in the region of latitude 52°N.) is indented by embayments and
amphitheatres, similar to those of ‘the border of the American
plateau. From the comparatively numerous soundings upon the
summit of the divide, and in the adjacent Arctic sea, the valleys
from the cols just mentioned, and many others, can be traced to
abyssmal depths. Thus, that between Greenland and Iceland
descends rapidly from a depth of 2,000 feet to 6,642 feet, and may
be followed to a depth of 9,000 feet. The valley in the opposite
direction from the same col, extends northward, and receives the
tributary from the Scoresby Sound (which is 1,800 feet deep far
within the Greenland mass). In latitude 74°, there is a remarkable
amphitheatre of 5,520 feet in depth; and just south-west of Spitz-
bergen, a similar amphitheatre of 8,100 feet in depth is found where
the plateau is submerged only a few hundred feet. Spitzbergen and ©
Norway are connected by a plateau which is generally depressed to
less than 1,200 feet. From it valleys descend to the Greenland sea.
Professor Spencer— Continental Elevation. OV
The Baltic valley hugs the coast of Norway, and beyond that it
extends to the same sea. From the col of the channel between
Faroe and Shetland, at a depth of somewhat more than 3,000 feet,
a great valley extends southward. North-west of Ireland, this
valley reaches a depth of 9,980 feet, upon the north-westward side
of which the plateau is characterized by: shallow banks; and it
continues to a depth of 12,000 feet at the margin of the plateau.
Tributary amphitheatres to this great valley may be seen westward
of Ireland. One of these is 8,160 feet deep, where the platform
has been depressed 5,040 feet; and two others have a depth of
10,500 feet, where the plateau is submerged only 4,000 feet. Further
- southward, extending from the oceanic basin, a large embayment
indents and extends far into the platform south-west of Ireland,
having still a depth of 10,500 feet, where the shelf is covered by
only about 2,500 feet of water. The Bay of Biscay is a remarkable
embayment of great depth, with tributary amphitheatres like those
just mentioned. The amphitheatres mentioned have no extraordinary
widths. Their land equivalents are characterized by inconsiderable
streams descending precipitously over steps from plateaux of great
altitude.
It is manifest, that Europe and Greenland form one continental
mass, while the latter country is separated by a much deeper sea
from the American continent. Accordingly, the search for these
drowned valleys should be made by means of numerous soundings
along lines parallel to the Iceland ridge, rather than off the coast
of Ireland. From the fragmentary knowledge already acquired,
it would be reasonable to expect the discovery of as complete
systems of river-valleys as those found off the American coast and
in the Antillean regions; indicating a late continental elevation of
12,000 feet or more.
Continental Elevation a Cause for Glacial Climate.
As has already been stated, the great continental elevation of
Eastern America occurred during the early Pleistocene period, and
was characterized by a stupendous amount of erosion, with the
production of cafions and amphitheatres (at the heads of the valleys).
Such an elevation of two miles or more, as measured by the depths
of the valleys, must have produced a glacial climate in the more
northern regions of America and of the North Atlantic. Thus
we find a cause for the Glacial epoch; but many of the
phenomena cannot be considered here. Whether the elevations
of the North Atlantic and the American regions were absolutely
simultaneous, or compensated each other with alternations, like the
Antillean and Mexican undulations, is not known. Such alternations,
with their diversions of the oceanic and atmospheric currents,
together with the more recent partial submergence of the northern
lands, would produce variations of the glacial phenomena, and would
bring into close proximity those of high elevation and submergence,
aud of warmer and colder climates.
From as yet unpublished data, it appears that the late Pleistocene
388 Notices of Memoirs—Prof. O. C. Marsh on Hesperornis.
depression of base-level in New England reached 2,700 feet at least.
As there was a Mid-Pliocene (our separation of Pliocene and
Pleistocene formations being largely arbitrary) elevation of unde-
termined amount, and as there have been several minor oscillations
of level of land and sea, there is great latitude in the application
of the phenomena to the Glacial epoch not yet determined—only
that great elevation of measurable amount did obtain in Pleisto-
cene days. With alternations of elevation between the North
Atlantic and American plateaux, the changes of currents would
further modify the climatic conditions of the period, so that this
paper only suggests one phase of physical changes—tending to
produce the phenomena of the Glacial period.
IN @ Per @ ser Sl @ ray aN aen VE @ ale Se
_——-——>—_—_
I.—Tue Arrinities oF Hespzroryis.. By O. C. Marsa.
N the autumn of 1870, I discovered in the Cretaceous of Western
Kansas the remains of a very large swimming bird, which in
many respects is the most interesting member of the class hitherto
found, living or extinct. During the following year, other specimens
were obtained in the same region, and one of them, a nearly perfect
skeleton, I named Hesperornis regalis.2 In subsequent careful —
researches, extending over several years, I secured various other
specimens in fine preservation, from the same horizon and. the
same general region, and thus was enabled to make a systematic
investigation of the structure and affinities of the remarkable group
of birds of which Hesperornis is the type. The results of this and
other researches were brought together in 1880, in an illustrated’
monograph.®
In the concluding chapter on Hesperornis, I discussed the affinities
of this genus, based upon a careful study of all the known remaius.
Especial attention was devoted to the skull and scapular arch, which
showed struthious features, and these were duly weighed against the
more apparent characters of the hind limbs, that strongly resembled
those of modern diving birds, thus suggesting a near relationship to
this group, of which Colymbus is a type. In summing up the case,
J decided in favour of the ostrich features, and recorded this opinion
as follows:—
“The struthious characters seen in Hesperornis should probably
be regarded as evidence of real affinity, and in this case Hesperornis
would be essentially a carnivorous, swimming ostrich.” (‘ Odontor-
nithes,” p. 114.)
This conclusion, a result of nearly ten years’ exploration and
study, based upon a large number of very perfect specimens and
a comparison with many recent and extinct birds, did not meet with
? From the American Journal of Science, vol. ii, 1897.
2 Silliman’s Journal, vol. iii, p 46, January ; and p. 360, May, 1872.
* « Qdontornithes: a Monograph on the Extinct Toothed Birds of North
America.’’ 4to, 34 plates; Washington, 1840.
Notices of Memoirs—Granites, &c., Lake Temiscaming, Canada. 39
general acceptance. Various authors who had not seen the original
specimens, or made a special study of any allied forms, seem to have
accepted without hesitation the striking adaptive characters of the
posterior limbs as the key to real affinities, and likewise put this
opinion on record. ‘The compilers of such knowledge followed suit,
and before long the Ratite affinities of Hesperornis were seldom
alluded to in scientific literature.
Several times I was much tempted to set the matter right as far
as possible by reminding the critics that they had overlooked
important points in the argument, and that new evidence brought
to light, although not conclusive, tended to support my original
conclusion that Hesperornis was essentially a swimming ostrich,
while its resemblance to modern diving birds was based upon
adaptive characters. On reflection, however, I concluded that such
a statement would doubtless lead to useless discussion, especially on
the part of those who had no new facts to offer, and, having myself
more important work on hand, I remained silent, leaving to future
discoveries the final decision of the question at issue.
It is an interesting fact that this decision is now on record.
A quarter of a century after the discovery of Hesperornis, and
a decade and a half after its biography was written in the
“Odontornithes,” its true affinities, as recorded in that volume,
are now confirmed beyond dispute. In the same region where the
type-specimen was discovered, a remarkably perfect Mesperornis, with
feathers in place, has been found, and these feathers correspond
with the typical plumage of an ostrich.'
IJ.—On tHe RELATIONS AND STRUCTURE OF CERTAIN GRANITES AND
AssocraTeD ARkosEs oN Lake TemiscaminG, Canapa.” By A. EH.
Bartow, M.A., and W. F. Ferrier, B.Sc., Geological Survey
of Canada.
\HE rocks to which the following facts relate outcrop on both the
eastern and western shores of Lake Temiscaming iminediately
north of the “Old Fort” Narrows on the upper Ottawa river, the
deep channel of which forms the boundary-line between the
Provinces of Ontario and Quebec.
On the eastern side of the lake the granite forms a strip along the
shore half a mile wide, extending from a point three-quarters of a mile
north of “The Narrows” on which is situated the now abandoned
Fort Temiscaming, a fur-trading post belonging to the Hudson Bay
Company, to the steamboat wharf near the village of Baie des Peres.
It also constitutes the rocky promontory known as Wine Point to
the west of Baie des Péres, extending inland in a north-easterly
direction for about one mile and a quarter. On the western side of
the lake the first outcrop is noticed about half a mile west of ‘‘ The
Narrows,” continuing along the shore for about four miles as far as
1 Williston, Kansas University Quarterly, vol. v, p. 53, July, 1896.
2 Abstract read before the British Association, Section C (Geology), Toronto,
1897.
40 Notices of Memoirs—Granites, §c., Lake Temiscaming, Canada.
Paradis Point, and varying in breadth from half a mile to one mile.
The whole area thus underlain by the granite is approximately about
Six square miles.
Macroscopically the fresh rock is a rather coarse, though very
uniformly even-grained aggregate of felspar, quartz, and a dark-
coloured mica, probably biotite. Felspar is by far the most abundant
constituent, and the abundance of red oxide of iron disseminated
through all the cracks and fissures of this mineral gives to the
rock its beautiful deep flesh-red colour. The quartz is, as usual,
allotriomorphic, but a decided tendency is noticed to segregate in
more or less rounded areas or individuals which, especially on
surfaces worn and polished as a result of glacial action, gives to the
rock a porphyritic or pseudo-conglomeratic appearance ; a fact first
made note of by Sir William Logan in 1844 on his manuscript map
of this portion of the Ottawa river.
The microscope shows the rock to be composed essentially of
orthoclase, microcline, plagioclase (oligoclase?), quartz, and biotite
almost completely altered to chlorite. ‘The microcline has evidently
been derived from orthoclase as a result of pressure, and all the
gradations of this change may be noted, from the ‘“ moire structure ”
characteristic of the imperfectly or only partially developed mineral,
to the fine and typical ‘cross-hatched structure” peculiar to this
mineral. The felspar shows only incipient alteration to sericite, and
scales and flakes of this mineral are developed especially abundantly
in the central portion of the individuals, leaving a comparatively
fresh periphery almost altogether free from such decomposition
products.
The arkose with which this granite is associated and surrounded is
a beautiful pale or sea-green quartzite or grit, passing occasionally
into a conglomerate, the pebbles of which are chiefly grey and red
quartz with occasional intermixed fragments of a halleflinta-like rock.
Under the microscope the finer-grained matrix appears to be
almost wholly composed of pale yellowish-green sericite in the form
of minute scales and flakes, although occasional individuals are
macroscopically apparent. Most of this sericite has originated from
the decomposition in siti of felspar originally present, and irregular
portions or areas of the unaltered felspar may be occasionally
detected.
The line of junction between this granite and arkose shows
a gradual and distinct passage outward or upward from the granite
mass. The series of thin sections examined, as well as the hand-
specimens themselves, show every stage in the process, which has
been carefully studied. °
In the first place, as a result of dynamic action, the orthoclase is
converted into microcline with the incipient development of sericite,
which gradually increases in those specimens where the greatest
perfection of the “cross-hatched” microcline structure is reached. In
these the individuals of quartz and felspar have undergone rather
extensive fracturing, but with little or no movement apart of the
fragments. This breaking up of the original larger individuals is,
Notices of Memoirs—Prof. T. R. Jones—Fossil Phyllopoda. 41
as usual, much more apparent in the quartz than in the felspar, and
beautiful examples of ‘strain-shadows” may frequently be seen in
those quartz areas which have not yielded altogether to the pressure.
A further stage in the process is reached when the sericitization of
the felspar has proceeded so far as to permit of the ‘‘ shoving apart”’
of the fragments by the various forces which have acted in bringing
about the degradation of the whole rock mass. This gradual decom-
position of the felspar and movement of the rock constituents can be
perfectly traced in the series of thin sections examined until the
rock cannot be distinguished from an ordinary arkose, while the
arrangement on the large scale, and the more or less parallel
alignment of rounded and waterworn quartzose fragments, amply
testify to the final assortment and rearrangement of the disintegrated
material as a result of ordinary sedimentation.
The relations between this granite and arkose are of rather
unusual scientific interest, showing, as they do, the Pre-Huronian
existence of a basement or floor npon which these sediments were
laid down, and which in this portion at least has escaped the
movements to which the Laurentian gneisses have been subjected.
The granite is also somewhat different, both in composition and
appearance, from the granites and gneisses classified as Laurentian,
and which are so frequently referred to as the Fundamental Gneiss
or Basement Complex, although during recent years the assumption
implied in these terms has been considerably weakened by the fact
that the contact between such rocks and the associated clastics is,
wherever examined, one of intrusion. On the other hand, the
composition of the Huronian strata furnishes indubitable evidence of
a pre-existing basement or floor essentially granitic in composition,
while the abundance of red granite pebbles and fragments, which
are so pre-eminently abundant in the breccia-conglomerate lying at
the base of the Huronian system, are very similar in composition and
appearance to the granite described above. This granite is, therefore,
regarded by the authors as the only instance at present known in
which the material composing the Huronian clastics can be clearly
and directly traced, both macroscopically and microscopically, to the
original source from which it has been derived.
II.—Tuas Fosstn Poytiopopa oF THe Parmozorc Rocks. Thirteenth
Report of the Committee, consisting of Professor T. Wiurssire
(Chairman), Dr. H. Woopwaxp, and Professor T. Rupert Jones
(Secretary). (Drawn up by Professor T. Rupert Jones.)?
§ I. 1889-1892. Anomalous Silurian Phyllopods (?) from
Germany and America.—In the Sitz.-Ber. Gesell. naturf. Freunde
zu Berlin, 1890, p. 28, Dr. A. Krause described a small fossil
carapace of doubtful alliance, but possibly related to the Phyllopods,
from the North-German gravel of Scandinavian Beyrichia-limestone
(Upper Silurian). In the Zeitsch. Deutsch. Geol. Gesell., vol. xliv,
1892, p. 397, pl. xxii, figs. 19 a-c, Dr. A. Krause redescribed
and figured this anomalous little fossil.
1 Read before the British Association, Section C (Geology), Toronto, 1897.
42 Notices of Memoirs—
Its lateral moieties are not free, separate valves, but united by an
antero-dorsal suture for a third of its length, and by an antero-
ventral suture for half of its length, the posterior region remaining
open at the edges. It also shows in front a round aperture, with
a sulcus formed by the somewhat inverted edges below it. The
test is nearly oval and compressed; thickest and subacute in front ;
bearing a small, low, subcentral swelling. The surface has some
reticulate ornament along the margins for the most part, succeeded
by linear, radiating, and concentric sculpture towards the more
convex area, which is finely punctate. It is 6mm. long, 4 mm. high,
and 1:5 mm. thick.
In §. A. Miller’s “North-American Geology and Paleontology,”
2nd edition, 1889, p. 549, fig. 1,009, an allied form is described and
figured as Faberia anomala, n. sp. et gen., from the Hudson-River
group, Obio (Lower Silurian). This has evidently some analogy to
the foregoing Upper Silurian form. It has a compressed, ovoidal,
smooth shell, consisting of two moieties. partially sutured above and
below, and is rather smaller than the German specimen.
§ Il. 1885-1894. Cambrian Phyllopoda (?).—-Dr. G. F. Matthew,
of St. John, New Brunswick, has discovered several very small
organisms in the Cambrian rocks of North-Eastern America, some
of which he regards, with doubt, as having been carapace-valves of
Phyllopodous Crustaceans. He has described and figured them in
the Transactions of the Royal Society of Canada.
To this group of small subtriangular valve-like bodies, obliquely
semicircular or semi-elliptical, with straight hinge-line and more or
less definite umbo, belong (1) Lepiditta alata, M., Trans. Roy.
Soc. Canada, vol. iii, 1885, sect. 4, p. 61, pl. vi, figs. 16, 16a;
(2) L. curta, M., p. 62, pl. vi, fig. 17; (8) Lepidilla' anomala, M.,
p- 62, pl. vi, figs. 18, 18a, b,c; (4) Lepiditta sigillata, M.,. xi, 1894,
sect. 4, p. 99, pl. xvii, fig. 1; (5) L. auriculata, M., p. 99, pl. xvii,
figs. 2, 2a, b. Some of these were referred to by us in the Sixth
Report (for 1888), p. 174.
§ III. 1889. Rhachura venosa, Scudder, 1878, Proc. Boston Soe.
Nat. Hist., vol. xix, p. 296, pl. ix, figs. 3, 3a (referred to in our
Report for 1888, p. 216). Dr. A. 8. Packard, having received from
M. Gurley some imperfect specimens found in the Middle Coal-
measures, Danville, Illinois, describes them as being parts of
a carapace, probably a little over three inches long, and three
caudal spines, also rather obscure (Proc. Boston Soc. Nat. Hist.,
vol. xxiv, 1889, pp. 212, 213).
§ 1V. 18938. Rhinocaris columbina.—Mr. J. M. Clarke has con-
tributed a paper ‘“‘On the Structure of the Carapace in the Devonian
Crustacean Rhinocaris, and the relation of the Genus to Mesothyra
and the Phyllocarida,” with illustrative cuts, published in the
American Naturalist, Sept. 1, 1893, pp. 793-801. The carapace-
valves of Rhinocaris columbina (J. M. C., “ Paleont. New York,”
1 Dr. G. F. Matthew, in a letter of November 5, 1897, expresses a ‘‘ wish to
withdraw Lepidilla, as not being a Crustacean; more perfect specimens seem
to show a fan-like structure of internal tubes.”
Professor T. Rupert Jones—Fossil Phyllopoda. 43
vol. vii, 1888, pp. Iviii and 195-7) are described from better speci-
mens, which show it to be a bivalved (not univalved) form, and as
having a narrow, median plate, of which there is evidence in
Alesothyra, making a double dorsal suture. There is also a long,
narrow, leaf-like rostrum inserted between the valves in front. The
relationship of this form with Mesothyra and Tropidocaris is dwelt
upon. ‘The author thinks that Dithyrocaris and Hmmelezoe have
some affinity with it. Rhinocaris and Mesothyra are regarded as
typical members of the family Rhinocaride. We may mention that
Dr. Matthew regards his Ceratiocaris pusilla from the Silurian of
New Brunswick (see Trans. Roy. Soc. Canada, vol. vi, 1888, sect. 4,
p: 56, pl. iv, fig. 2; and our Seventh Report, for 1889, p. 64) as
Rhinocaris.
§ V. 1895. Hmmelezoe Lindstroemi.—Since our Twelfth Report,
presented to the British Association at Ipswich in 1895, the Swedish
Phyllocarids mentioned in that Report as having been found by
Dr. Gustav Lindstrém in the Upper Silurian beds at Lau, Gothland,
have been duly described and figured in the GeoLtoeicaL MaGazine,
Decade IV, Vol. II, No. 378, December, 1895, pp. 540, 541, PL XV,
Figs. 2a—2d, as Hmmelezoe Lindstroemi, J. and W. he fish-remains
(Cyathaspis) and other fossils associated with it are mentioned in
detail by G. Lindstrém in the Bihang till K. Svensk. Vet.-Akad.
Handal., vol. xxi, part 4, No. 8, 1895, pp. 11, 12.
Mr. J. M. Clarke has suggested at p. 801 of his memoir, mentioned
in § LV, that the oculate genus Hmmelezoe may have some relation-
ship to the group to which Rhinoearis belongs.
§ VI. 1895. Pinnocaris Lapworthi.—This genus, represented by
its only known species, P. Lapworthi, has been carefully examined
by Woodward and Jones, and several specimens described, selected
from a large number in Mrs. Robert Gray’s collection at Edinburgh.
This memoir appeared in the GrotogrcaL Macazine, Decade LV,
Vol. II, 1895, pp. 542-5, Pl. XV, Figs. 5-10. Excepting one
specimen from the Upper Silurian of Kendal, Westmoreland, all
the known specimens are trom the Lower Silurian of Girvan,
Ayrshire, where Mrs. Gray has made a large collection.
The peculiar “corded” dorsal margin of the valves may have
reference to some longitudinal, narrow, intermediate ligament or
plate as in Rhinocaris and Mesothyra.
§ VII. 1895. A new species of Ceratiocaris (C. reticosa, J. and
W.), preserved in the Museum of the Geological Survey, was de-
scribed in the GrotocicaL Macazrine, Decade IV, Vol. II, 1895,
pp- 539, 540, Pl. XV, Figs. la, 1b. It is from the Silurian beds of
Ludlow, Shropshire, and is allied to C. casstoides, from that locality.
‘Traces of a peculiar reticulate sculpture constitute its distinguishing
feature.
§ VIII. 1895. Lingulocaris.—In the same number (378) of the
GerotocicaL Magazine, 1895, at pp. 541, 542, a specimen Lingulo-
caris lingulecomes, Salter, belonging to the Rev. G. C. H. Pollen,
b.J., F.G.S., was figured and described. It came from Capel Arthog,
North Wales, probably from the Ffestiniog or middle division of the
44 Notices of Memoirs—Prof. T. R. Jones—Fossil Phyllopoda.
Lingula-flags. Hence we may add “ Lingulocaris” to ‘“ Hymenocaris”
for that formation at p. 425 of our Twelfth Report (fifth line from
the bottom).
§ IX. 1896. Devonian species of Ceratiocaris (?).— In the
* Monograph of the Devonian Fauna of the South of England,”
Paleont. Soc., vol. iii, part 1, 1896, the Rev. G. F. Whidborne
describes and figures three obscure casts of Ceratiocaris, one C. (?)
subquadrata, sp. nov., p. 7, pl. 1, fig. 5, from Hast Anstey ; another,
Ceratiocaris (?) sp., p. 8, pl. 1, fig. 6, from Sloly; and the third,
somewhat indistinct specimen, namely Ceratiocaris (?) sp., p. 8,
pl. ii, fig. 12, from Croyde.
§ X. 1896. Hntomocaris and Ceratiocaris.— A collection of
Ceratiocaris-like Crustaceans from the Lower Helderberg Formation
(Upper Silurian), near Waubeka, Wisconsin, has afforded Mr. R. P.
Whitfield, of the American Natural History Museum, New York,
the opportunity of determining two new species of Ceratiocaris, and
a new genus (nxtomocaris), allied to Ceratiocaris, but differing from
it by the carapace-valves being “strongly curved in front and
behind on the dorsal margin,” and by the posterior margin not
being truncate, as in Ceratiocaris, but obtusely rounded. Lntomo-
caris Telleri, Whitfield (p. 800), is figured in pl. xii, of full size,
but slightly distorted by pressure. Including the four exposed
body-segments and the trifid appendage, it is about 21 centimetres
(about 8 inches) long; and the valves are about 154 centimetres
long by about 64 high. Some indications of the swimming-feet
attached to the body are visible where one valve has been partially
broken away from the internal cast. Some mandibles, supposed to
belong to this species, are shown in pl. xiv, figs. 1,2; and the caudal
appendages in fig. 9.
Ceratiocaris Monroet, Whitfield (p. 501, pl. xiii, figs. 1-5, and
pl. xiv, figs. 3-8), is carefully described from one nearly perfect
and an imperfect specimen, together with body-segments, caudal
appendages, and some mandibles. The carapace-valves seem to
have been about 74 centimetres long and 4 high.
Ceratiocaris poduriformis, Whitfield (p. 502, pl. xiv, fig. 10), is
represented by a small specimen of abdominal segments and caudal
spines.
§ XI. 1896. Echinocaris Whidbornei, J. and W., noticed in our
Seventh Report (for 1859), p. 63, has been redescribed and refigured
by the Rev. G. F. Whidborne in the “Monogr. Devonian Fauna,
S. England,” Pal. Soc., vol. iii, part 1, 1896, p. 6, pl. i, fig. 3.
Within the last few months Ananda K. Coomary-Swamy, Esq., of
Warplesdon, has fortunately obtained a very interesting specimen of
this Hchinocaris from the Sloly mudstone, showing on the two
counterparts of the little split slab, two individuals, each having the
same characters as the specimen first described in the GnoLoatcaL
Magazine, Decade III, Vol. VI, 1889, p. 385, Pl. XI, Fig. 1.
Though rather narrowed by oblique pressure, the valves are equal
in breadth to those of the first specimen. An additional feature of
interest is seen in some body-segments, five in one individual and
Reviews—Harker’s Petrology for Students. 45
three in the other. In each case, though the series of segments is
not complete either at beginning or end, they are characteristically
like those of Hchinocaris, the distal edges bearing tubercles, the
equivalents of spinules.
§ XII. 1896. Caryocaris.—In the Journal of Geology, Chicago,
vol. iv, 1896, p. 85, Dr. R. R. Gurley has described Caryocaris as
the “lateral appendages” of the “polypary” of a Graptolite !
Caryocaris was referred to by us in the First and Seventh Reports
(for 1883 and 1891), and was described in detail and figured in the
** Monogr. Brit. Paleeoz. Phyllocarida,” Pal. Soc. 1892, p. 89 et seq.,
pl. xiv, figs. 11-18.
§ XIII. 1897. A new locality in Nova Scotia has been deter-
mined by Sir William Dawson for Estheria Dawsoni, namely, Kast
Branch, East River, Pictou County, Lower Carboniferous. Several
casts and impressions of small valves, not more than two millimetres
long, occur on the bed-planes of a dark-red Lower Carboniferous
shale. Former occurrences of this species were noticed in our
Report (Hleventh) for 1894.
I5y) Ja W/ JE Jah WY SE
Perrotoegy FoR Stupents: An InrRopucTION TO THE SruDY
or Rocks UNDER THE Mrcroscopr. By Atrrep Harker,
M.A., F.G.S. Second edition, revised. 3834 pp., 75 figs. (Cam-
bridge : Messrs. C. J. Clay & Sons, 1897. Price 7s. 6d.)
HE appearance within two years of a second edition of so
excellent a textbook as Harker’s “‘ Petrology for Students” is not
a subject for surprise. In this revised edition the author states that
he has endeavoured to profit by the criticisms of reviewers and
private friends. The slight alteration, however, which the book has
undergone shows how little cause for adverse criticism there was
in the first edition. In general plan and scope the book remains
precisely the same. Only about thirty pages have been added, and
these are mainly due to the introduction of descriptions of American
examples among the igneous rocks, one result of which is, that the
reader makes the acquaintance of a number of those new names
(Absarokite, Banakite, Carmeloite, Shonkinite, etc.) to the invention
of which American geologists have of late been perhaps a little too
prone.
The method of classification of the igneous rocks remains
practically the same, but Brogger’s name “hypabyssal”’ is sub-
stituted for “intrusive.” As the author remarks, “ petrology has
not yet arrived at any philosophical classification,” and certainly the
attempt to pigeonhole the igneous rocks, both basic and acid, into
the three groups, plutonic, hypabyssal, and volcanic, involves
inconsistencies which are evident in the text. Thus three chapters
intervene between the descriptions of such similar rocks as the
pitchstones of Arran and the ‘pitchstones” (or, as the author
prefers to call them, the Permian rhyolites) of Meissen; while the
46 Reports and Proceedings— Geological Society of London.
treatment of the Derbyshire ‘“ toadstones” rather leaves the im-
pression that they would have been described in connection with
the Shropshire “diabases” but for the fact that “Mr. Arnold
Bemrose regards them as contemporaneous lavas.” That there
should be any difficulty in naming a rock before its mode of
occurrence, either as an intrusive mass or as a lava-flow, has been
determined, may present no terrors to the field-geologist ; but to the
Museum-Curator it is hardly less appalling than the idea that before
giving a rock a name it is necessary to determine its geological age.
The author, it is true, is faithful to the British School in rejecting
any distinction between rocks drawn from geological age; but the
simplification in classification which should follow the removal of
this incubus is partly discounted in this, as in many other English
textbooks, by the fact that the hypabyssal groups are to a large
extent recruited from rocks which are so mildly intrusive as to be
included by Continental writers in their paleovolcanie groups
(Hrgussgesteine).
The book has been brought up to date by references to recent
work, and still remains, what it was recognized to be on its first
appearance, one of the most trustworthy guides for the student who
wishes to take up the microscopic study of rocks. Ga aie
aS ah SOS) /NINMD)) d354O\Caz pap Dslsy GrS-
GerotocicaL Socrery oF Lonpon.
I.—November 17, 1897.—Dr. Henry Hicks, F.R.S., President,
in the Chair. The following communications were read :—
1. “The Geology of Rotuma.” By J. Stanley Gardiner, Esq.,
B.A. (Communicated by J. EK. Marr, Hsq., M.A., F.R.S.)
The author describes the relationship of the island of Rotuma
(situated in lat. 12° 380’ S., long. 177° 1’ E.) to the adjoining isles.
It is almost separated into two parts, which are united by a narrow
neck of sand. The interior is composed of volcanoes, which have
emitted lavas and fragmental rocks. Around the volcanic rocks are
stratified deposits composed of sea-sand with volcanic fragments.
These are partly denuded, and are mantled round by coral-reef and
beach sand-flats. A remarkable cavern in the lava of Sol Mapii,
with lava-stalactites, is described; there is a similar cavern in
Au Huf Hof.
An account of the prevalent meteorological conditions is also given.
In an Appendix by Mr. H. Woods, M.A., some of the rocks are
described. They consist of olivine-dolerites and basalts and asso-
ciated fragmental rocks.
2. “ A Geological Survey of the Witwatersrand and other Districts
in the Southern Transvaal.” By Frederick H. Hatch, Ph.D., F.G.S.
After giving an account of the physical characters of the area,
the author proceeds to describe the various rocks referred to
(1) The Karoo System,
(2) The Cape System,
(3) The Primary or Archvan System.
Reports and Proceedings—Geological Society of London. 47
The Archean rocks protrude in a few places through the sedi-
mentary beds, which form the greater part of the area, and consist
of an igneous complex of rocks of varied composition.
The Cape System is capable of division into five distinct series :—
Magaliesbere and Gatsrand series; alternating quartzites, shales, and
( to) 5 to) q > b)
Ween | lava-flows. 16,000 to 20,000 feet.
Beds 4 Dolomite and cherts, thickly bedded. 6,000 to 8,000 feet.
"| Black Reef; a bed of quartzite and conglomerate, 20 to 50 feet, and
Klipriversberg amygdaloid; a basic volcanic rock, 5,000 to 6,000 feet.
Witwatersrand Beds; sandstones and conglomerate (in part auriferous).
LoweEr 11,000 to 15,000 feet.
Bzps. ) Hospital Hill series; quartzites and ferruginous shales. 8,000 to
10,000 feet.
A full description of each of the series, and the associated volcanic
and igneous rocks, is given in the paper.
The Karoo formation is represented by the Coal-measures of
Vereeniging and the district south of Heidelberg, and by the
measures of other coal-areas. They have furnished plants which
Mr. Seward refers to in a note as being of Permo-Carboniferous age.
The age of the Cape System is doubtful. The Upper beds rest
unconformably on the Lower ones, and if the latter be of Devonian
age, aS has been inferred, the former may represent the Lower
Carboniferous rocks.
In conclusion the author makes some observations upon the
geotectonic relations of the area.
3. “Observations on the Genus Aelisina, De Koninck, with
Descriptions of British Species, and of some other Carboniferous
Gastropoda.” By Miss J. Donald, of Carlisle. (Communicated by
J. G. Goodchild, Esq., F.G.S.)
The author makes some preliminary observations on the genus
Aclisina, and considers it advisable to regard A. pulchra as the
type of the genus, while the so-called A. striatula must be placed
among the Murchisonig, and A. nana is placed in a new genus.
The author gives a diagnosis of Aelisina, De Kon., belonging to
the family Turritellide, and describes the British species, twelve of
which are new, including two new forms placed in a subgenus.
Of the family Murchisonide, and in the section Aclisoides of
the genus Murchisonia, the form of A. striatula, De Kon., and a
variety are described; and a diagnosis of the new genus, in which
A. nana of De Koninck is placed, is given, followed by a description
of the species.
TI.—December 1, 1897.—-Dr. Henry Hicks, F.R.S., President, in
the Chair. The following communications were read :—
1. “A Revindication of the Llanberis Unconformity.” By the
Rev. J. F. Blake, M.A., F.G.S.
In a paper published in the Quarterly Journal of the Society
for 1895, the author of the present paper maintained that certain
conglomerates and associated rocks occurring for some distance
north-east aud south-west of Llanberis, which had hitherto been
48 DPeaalRraacons.
considered to lie below the workable slates of the Cambrian rocks
of that area, were in reality unconformable deposits of later date
than those slates. In 1894 (Quart. Journ. Geol. Soc., vol. u, p. 578),
Professor Bonney and Miss C. A. Raisin maintained that in no case
which they had examined could any valid evidence be found in favour
of the alleged unconformity, and that in one (on the north-east side of
Llyn Padarn) which they supposed to afford the most satisfactory
proof of it, the facts were wholly opposed to the notion.
The present paper is a reply to these authors, in which ast
objections, founded on general considerations, on field observations,
and on microscopic examination of rock-specimens, are discussed,
and the author gives the results of further observations on the
rocks of the district. 'The Moel Tryfaen sections and those on each
side of Llyn Padarn in the Llanberis district are considered, and
he maintains that the post-Llanberis (using this term in the sense
of being after the deposition of the main workable slates) age of the
conglomerates which are under discussion is established; though
the more he considers the correlation of these conglomerates with
the Bronllwyd Grits the less he likes it, and as far as the strati-
graphy is concerned, they may be much newer—their age is at
present an open question; but of their unconformable position he
has no doubt.
2. “The Geology of Lambay Island, Co. Dublin.” By Messrs.
C. I. Gardiner, M.A., F.G.S., and §. H. Reynolds, M.A., F.G.S.
The authors, who have previously described the neighbouring
district of Portraine (Quart. Journ. Geol. Soc., Dec. 1897), under-
took an examination of this island, with the intention of comparing
the rocks with those of Portraine, and of investigating the nature of
the rock familiar to geologists under the name of ‘“ Lambay
porphyry.” The sedimentary rocks are similar to some of those
of Portraine, and are of Middle or Upper Bala age. Associated with
them are pyroclastic rocks and andesitic lava-flows, some of the
lavas having flowed beneath the sea. The sediments and volcanic
rocks were exposed to denudation, and a conglomerate composed of
their fragments was accumulated round the volcano. The “ Lambay
porphyry,” which has been determined as a diabase-porphyry by
Dr. von Lasaulx, is partly intrusive in the other rocks, but has in
places come to the surface as a lava-flow.
Petrographical descriptions of the various rocks are given by the
authors.
IMEIES Oss En IE) /A IN fasHO) US
ies PaaS
New GeotocicaL Survey Mars. — Since our notice in the
GeotocicaAL Magazine for 1897, p. 192, several other of the
Sheets of the General Map of England and Wales (scale one-inch
to four miles) have been issued, printed in colours and priced 2s. 6d.
each. ‘These include Sheets 2, Northumberland, etc.; 8, Index of
Colours; 4, Isle of Man; 7, North-West Wales; 10, Parts of South
Wales and North Devon; and 18, Cornwall and the Scilly Isles
with part of Devon.
GEOL. Mac. 1808. Decade IV, Vol. V, Pl. IL
Antlers of the great Red-Deer, Cervus elaphus, Linn.
Alport, Youlgreave, Bakewell, Derbyshire.
[Described in Phil. Tyans., 1785, vol. Ixxv, p. 353-]
Reduced to 7; natural size.
THE
GEOLOGICAL MAGAZINE
NEW SERIES. DECADE IV. VOL. V.
No. II.—FEBRUARY, 1898.
ORIGINAL ARTICLES.
L.—Nors on roe Antirrs or A Rep-Derr (Cervus nnapuus, Linn.)
From ALporT, YOULGREAVE, NEAR Bakrwett, DerpysHire
—now in the British Museum (Natural History), Cromwell:
Road, London. |
By Hexry Woopwarp, LL.D., F.R.S., V.P.G.S., ete.
(PLATE II.)
i 1891, Frank §. Goodwin, Hsq., of Bakewell, Derbyshire,
presented to the British Museum (Natural History) a pair of
antlers of red-deer, with fragments of the calvarium attached, which
had been obtained, with other cervine remains, from a tufaceous:
deposit of comparatively modern date near Bakewell, Derbyshire.
Owing to the loss of all animal matter the antlers were in a very:
friable condition and fell in pieces on being handled, although at
some distant time they had been repaired partially with long strips
of calico.
Two causes rendered them of interest: firstly, they were of
unusually large size, resembling the great American Wapiti (Cervus:
Canadensis) in stoutness and length of beam; secondly, they proved
to have been described in a letter from the Rev. Robert Barber, B.D.,:
to John Jebb, Esq., M.D., F.R.S., which was published in the Phil,
Trans. Royal Society for 1785 (vol. Ixxv, p. 353).
Notwithstanding their almost hopeless state of dilapidation, they
attracted the attention of Sir Edmund Giles Loder, Bart., and
Mr. J. G. Millais (the latter of whom examined and made drawings
of them about a year ago). An attempt was made to bring
the broken antlers together again ; and after much time and labour
expended by Mr. C. Barlow, the Formatore, they have at length
been successfully rehabilitated, and are now exhibited on the top of
pier-case No. 16, in the Geological Gallery devoted to fossil Mam-
malia, where they form, from their size and whiteness, one of the
most striking objects in the series of cervine remains.
The following is the account printed in the Phil. Trans. R.S. for
1785 (vol. Ixxv, p. 853), read April 14th, 1785 :—
DECADE IV.—VYOL. V.—NO. II. 4
00 Note on Antlers of Red-Deer from Bakewell, Derbyshire.
“About five years ago, some men working in a quarry of that
kind of stone which in this part of the country we call ‘tuft’ [tufa],*
at about five or six feet below the surface, in a very solid part of the
rock, met with several fragments of the horns [antlers] and bones of
one or different animals.
« Amongst the rest, out of a large piece of the rock which they got
entire, there appeared the tips of three or four horns [antlers] pro-
jecting a few inches from it, and the scapula of some animal adhering
to the outside of it. A friend of mine, to whom the quarry belongs,
sent the piece of the rock to me, in the state they got it, in which
I let it remain for some time.
“But suspecting that they might be tips of the horns [antlers]
of some head enclosed in the lump, I determined to gratify my
curiosity by clearing away the stone from the horns [antlers]. On
doing which, I found that the lump contained a very large stag’s
head, with two antlers upon each horn, in very perfect preservation,
inclosed in it.
“Though the horns [antlers] are so much larger than those of any
stag I have ever seen, yet, from the sutures in the skull appearing
very distinct in it, one would suppose that it was not the head of
a very old animal.
“T have one of the horns nearly entire, and the greatest part of
the other, but so broken in the getting out of the rock, that one part
will not join to the other, as the parts of the other horn [antler] do.
“The horns [antlers] are of that species which park-keepers in
this part of the country call ‘throstle-nest horns,’ from the peculiar
formation of the upper part of them, which is branched out into
a number of short [tines or] antlers which form a hollow about
large enough to contain a thrush’s nest.
‘“‘T send you the dimensions of the different parts of them, com-
pared with the horns [antlers] of the same species of a large stag
which have probably hung in the place from whence I procured
them, two or three or perhaps more centuries; and with another
pair of horns [antlers] of a different kind which are terminated by
one single pointed antler and which were the horns [antlers] of
a seven-year-old stag [Cervus elaphus |.
‘‘The river Larkell runs down the valley, and part of it falls
into the quarry where these horns [antlers] were found, the water of
which has not the property of incrusting any bodies it passes through.
“Jt is therefore probable that the animal to which these horns
[antlers] belonged was washed into the place where they were
found, at the time of some of those convulsions which contributed to
raise this part of the Island out of the sea.
« Besides this complete head, I have several pieces of horns, bones
(particularly the scapula I mentioned above), and several vertebree
of the back found in the same quarry; some, if not all, of them
probably belonging to the animal whose head is in my possession.
1 Tuft (¢fa) is a stone formed by the (calcareous) deposit left by water passing
through beds of sticks, roots, vegetables, etc., of which there is a large stratum at
Matlock Bath, in this county.
—_—-
J. E. Marr and R. H. Adie—The Lakes of Snowdon. 51
Dimensions oF THE Horns [ANTLERS] FouND at ALport.
ft. ins.
Circumference at their insertion into the corona .., ats ae Oe
a. Length of the lowest antler [brow-tine | 000 Has coo LD
6. Length of the second antler [bez-tine | : B05 bats 114
c. Length of the third antler [trez-tine] ... De wes ae ie Le
Length of horn antler [in the beam] ... ee 600 coo | ia) aes
Dimensions or Lance Parr or ‘ THrostie-nest Horns’
(ORDINARY Rep-DrEr ANTLERS).
ft. ins.
Circumference at their insertion into the corona ... as 500 7
a. Length of the lowest antler {brow-tine] oa bine Pa O
b. Length of the second antler {bez-tine] ... 104
c. Length of the third antler [trez-tine] ... wee 00 bb 114
Length of horn antler [in the beam] ... a3 300 eel! |e VOY
Dimensions oF THE Horns or Aa Stag Seven YEARS Op.
ft. ins.
Circumference at their insertion into the corona ... BB 200 Ox
a. Length of the lowest antler [brow-tine ] tae uae oo 9
b. length of the second antler [bez-tine]... es “oe tee 10
c. Length of the third antler [trez-tine] ... Bhs Le pn 10
Length of horn antler [in the beam] ... ae 00C coo | BF
«6 Youlgreave, January 25rd, 1785.”
P.S.—The following measurements have been taken since the
antlers have been repaired and mounted in the Gallery.!
MzasuREMENT OF ANTLERS OF Cervus elaphus FROM ALPORT, YOULGREAVE.
ft. ins
Width at the ‘‘nests”’ ... 200 be 500 Eco aaa)
Length of right antler ... 260 be 000 Bee) eg AO
Pe aslett 99 066 é0 bc Bee eon 8
5) pp RON SUI) | oo baa GbG. Hse SHEE G00 11
Maeda 55 so oot oo 600 ely Munle vt)
WN STU he ase cde hy ou, TSN TAG ee ERT SO
Girth of pedicle 74
», above the burr oF
Me », Ist tine oe ae cod ce 9f
um pp) ean pe 500 900 6oc ee boc 65
a PuKords, a4 on Sc ask S06 ie 65
IJ.—Tue Lakes or Snowpon.
By J. E. Marr, M.A., F.R.S., and R. H. Aprz, M.A., F.C.S., Lecturers of
St. John’s College, Cambridge.
M\HE waterways of Wales owe their directions to a complex series
of events which it is not our province to discuss in this place,
but the minor features of Snowdonia are largely determined by
planes of weakness which were produced in the rocks of the region
during the occurrence of the marked earth-movements at the close
of Silurian and Carboniferous times. The Post-Silurian earth-move-
ments gave rise to planes of weakness running in a general north-
east and south-west direction, and in a direction at right angles
1 See also ‘‘ British Deer and their Horns,”’ by J. G. Millais, p. 96, fig. 2, and
p- 105. (Roy. 4to; Sotheran & Co., 1897.)
52 J. E. Marr and R. H. Adie—The Lakes of Snowdon.
to this. Amongst other features parts of the coastlines of Anglesey
are determined by these planes of weakness. The Post-Carboniferous
planes run approximately north-and-south and east-and-west. The
Glaslyn below Beddgelert runs generally along a north-and-south
plane and the Capel Curig Valley along one extending in an east-and-
west direction.
The Snowdon mass, with its northern prolongation forming the
Moel Hilio range, is of a rectangular shape. It is about ten miles
long, and has an average width of about four miles. The ridge runs
in a general north-west and south-east direction, whilst the ends are
at right angles to this, for the Snowdon mass is bordered by
depressions coinciding with planes of weakness produced during
the Post-Silurian period of earth-movement. On the north-east side
the mass is bounded by the upper portion of the Seiont Valley,
containing the two lakes of Llanberis; on the south-west side by the
upper part of the Gwrfai Valley, holding the lakes of Cwellyn and
Llyn-y-gader, and the head of Nant Colwyn; the south-eastern
boundary is formed by the Vale of Gwynant, with Llyn Gwynant
and Llyn-y-ddinas; and on the north-west is a portion of the Seiont,
east of Carnarvon, which has worn its bed along the soft Arenig
shales. Of ridges determined by the Post-Silurian changes, the pre-
vailing one is that which runs north-west and south-east from Moel
Hilio, through Moel Goch and Moel Cynghorion, over the summit —
of Snowdon, and is continued to the south-west as the buttress of
Lliwedd. At right angles to this is the ridge of Crib-y-ddysgl, and
also the ridge running from Snowdon on the Beddgelert side known
as Llechog, part of which, however, runs parallel 1 to the north-west
and south-east system, as does also the ridge which culminates in
the peak of Yr Aran. Of the ridges determined by the north-and-
south and the east-and-west planes of weakness, the most important
are that of Crib Goch, which runs east and west, and that extending
between Snowdon and Y Geuallt, which is at right angles to this.
Bounded by these ridges and others having the same general directions,
lie the six beautiful ecwms of Snowdon, four of which contain one
or more lakelets. We have laid stress upon the planes of weakness,
because they contribute some information concerning the origin of
the lakelets. The south-eastern and south-western shores of Liyn
Llydaw are defined by two Post-Silurian planes of weakness. In
the cwm on the west side of Snowdon, the three upper tarns, Llyn
Glas, Llyn Coch, and Llyn-y-nadroedd, occur on a north-east and
south-west line; the stream from the central one, Llyn Coch, runs
at first along a north-west and south-east line, and this, if continued,
runs along the long axis of Llyn Ffynnon-y-gwas.
The principal precipices of Snowdon occur on the north-east side,
and the same feature is seen in the case of the Glyder range; and
in the Lake District the east side of the Helvellyn and High Street
ranges is the precipitous one. Minor examples may readily be |
called to mind showing a precipitous eastern slope and gentle
western one, and the cases are too frequent to be merely accidental.
It is possibly due to the rainfall from the south-west, and the south-
J. EH. Marr and R. H. Adie—The Lakes of Snowdon. 58
westerly aspect of the slopes causing much vegetation to grow on
the south-west faces of the hills and giving rise to peat-mosses,
thereby allowing the waters to discharge gently instead of running
off at once. In connection with this, we may notice that the
streams on the north-east side of the Snowdon range are gradually
cutting their way back into the hills, thus shifting the watershed
to the south-west of its general trend where these notches are formed.
This is specially well seen in the case of the passes of Maes Cwm
and Cwm Brwynog between Snowdon and Moel Hilio.
The literature dealing with the Snowdonian Lakes is not ex-
tensive. No doubt all geologists have read the masterly account
of “The Old Glaciers of Switzerland and North Wales,” by Professor
Ramsay, which originally appeared in the series of “ Peaks, Passes,
and Glaciers,” and was afterwards published separately in 1860.
Recently Mr. W. W. Watts contributed “ Notes on some Tarns near
Snowdon,” which will be found in the Report of the British
Association for 1895 (p.683) and also in this Magazine (Dec. IV, 1895,
Vol. I, p. 565). During last Easter Vacation we paid some attention
to the lakes and tarns of Snowdon, and believe that our observations
may be of some use as a small contribution to the subject of the
origin of lakes. In the first place we will deal with the lakes of
the larger valleys of the Seiont, Gwrfai, and Gwynant, and then
notice the lakes and lakelets which lie embosomed in the upland
hollows of Snowdon.
The Seiont, rising at the Pass of Llanberis, flows in a north-
westerly direction through the two lakes of Llanberis, Llyn Peris
and Llyn Padarn. These lakes were once one, and are now separated
by the alluvial strip near Dolbadarn Castle. This strip is part of the
delta brought down by the stream which descends from the heights
of Snowdon and Moel Hilio, and it is of interest to notice that at
one time a considerable bay must have extended up the valley
occupied by this stream, for alluvium extends some way towards the
waterfall Ceunant Mawr. In Llyn Peris there is a bay on the
south-west side of the lake, which is continued landward as a valley
of some importance, down which a stream of minute proportions
runs, and consequently the sediment which it has borne down has
been insufficient to fill up the bay. Several similar bays at one
time marked the south-west shores of Llyn Padarn, but as the lakes
of Llanberis are now used as receptacles for slate-rubbish, the
primary features of their shore-lines are almost obliterated. Llyn
Peris once extended much further up the valley, as shown by the
strip of alluvium extending to Gwastadnant.
The present exit of the river from Llyn Padarn is between two
rocky masses, but there is a considerable width of ground, on which
the bridge at Cwm-y-glo is built, which shows no rock in siti, though
it probably exists at no great depth beneath the surface. A depression
occupied by alluvium leaves the lake on its western side, about a
quarter of a mile south of the present exit, and curving round a rocky
knoll joins the present stream opposite the village of Cwm-y-glo.
It is somewhat over 100 yards wide in its narrowest part (where it
04. J. BE. Marr and R. H. Adie—The Lakes of Snowdon.
leaves the lake at the north end of the railway tunnel), and the
alluvium is just above lake-level. There is no stream of any im-
portance in this valley, and it is difficult to account for its existence
unless we suppose that the main river ran through it, and that it
became filled with drift, causing the formation of the lake, which
drained over what was formerly a low col, situated at the present
exit. Near the point where this old valley joins the present one,
are several large pools in the present valley surrounded by alluvium.
They are probably ‘kettle-holes” in the drift. The floor of the
Seiont Valley is occupied by drift all the way from the lake to the
sea, so that it is quite possible that the floor of the lake may be below
sea-level and yet that the lake may not be in a rock-basin.
We now proceed to consider the two lakes of the Vale of Gwynant.
Hach is about three-quarters of a mile in length, and has its longer
axis running in the direction of the valley. Llyn Gwynant is the
higher of the two, and the bottom of the valley is occupied by dritt
between its foot and the head of Llyn-y-ddinas. At the head of
the latter lake, the river has partly cut its valley through this drift,
but without reaching the rock. The exit from this lake is apparently
over rock, though no actual rock is seen in the stream at the outlet,
but the width of the area devoid of rock is here very small. A bold
rocky eminence lies between the foot of the lake and the road; the
road is carried along a drift-filled depression west of the present
exit for a short distance, and to the north of this the drift-filled
depression is seen north of the road, and joins the lake a few
hundred yards above the exit. This depression is about thirty yards
wide in its narrowest part. To the south-west it joins the drift-
covered bottom of the valley, and this valley-bottom is covered with
drift to some distance below Beddgelert. It may be noted that
Beddgelert stands on an alluvial flat which was once an old lake,
and a barrier of rock runs across the stream at the entrance to the
Pass of Aberglaslyn, but a drift-filled depression is seen to the west
of this, which joins the main valley a short way down the pass.
The lakes in the Gwrfai Valley present points of some interest.
Llyn Cwellyn is 464 feet above sea-level. An alluvial flat runs for
half a mile from the foot of the lake, and no doubt marks a former
portion of the lake filled up by the sediment brought down by the
small streams from Moel Hilio and Mynydd Mawr. The water then
runs over rock forming the cascade at Nant Mill, and the head of
this cascade is only about five feet below the level of Cwellyn. At
this point a barrier of rock extends right across the valley in such
a way as to forbid the existence of any drift-filled depression, which
could account for the lake. We lay special stress upon this point,
for it might be urged that a possibie drift-filled channel could be
indicated in the case of all lakes, owing to the large extent of
ground where live rock is not seen as compared with that which
shows the rocks in sit. One of us has had considerable experience
in the examination of the exits of lakes, and has found so many
(like Llyn Peris and Llyn-y-ddinas) where there is only one possible
exit, that he felt sure that if rock-basins exist with any frequency in
J. BE. Marr and Rk. H. Adie—The Lakes of Snowdon. +595)
Britain, there must be some where proof is obtainable that there is
no possible drift-filled exit. Cwellyn illustrates this: there is no
possible exit at the foot, and if this lake were backed by high hills
towards the head, the existence of a rock-basin could be proved here ;
but, as we shall now proceed to point out, the physiographical features
at the head of the lake are compatible with the existence of a drift-
filled depression in this direction ; and, indeed, some of the phenomena
exhibited above the head of Cwellyn are extremely difficult to
explain, unless such a depression exists there.
_ An alluvial flat extends above Cwellyn for a quarter of a mile up
the Gwrfai. This river runs over solid rock at Rhyd-ddu between
Owellyn and Llyn-y-gader, but a drift-filled depression is traceable
from the head of the alluvial flat, firstly up the main stream, then up
a tributary joining it a few yards south-east of Cwellyn Slate Quarry ;
it crosses a low watershed at a height of 740 feet (i.e., nearly 300 feet
above the surface of Cwellyn, and nearly 150 feet higher than that
of Llyn-y-gader), just east of Ffridd Slate Quarry, after which it
follows another small stream and joins Llyn-y-gader close to the
prominent crag, which stands out of the allavium on the east side of
the lake. This is the only possible exit in this direction, and its
resemblance to a drift-filled gorge is very striking. The depth of
Cwellyn is, so far as we are aware, not known; but assuming it is
nearly 50 feet deep, the gorge, which is about 80 yards wide at the
narrowest part, would require to be 3850 feet deep at this point, in
which case it would be comparable with some of the Alpine gorges.
Such gorges might well be cut by the water issuing from a glacier,
and highly charged with sediment, and the nature of the ground is
favourable for the formation of one at this point, for it is occupied
by a well-jointed basic intrusive rock. Furthermore, the rock comes
to the surface here so extensively, that there is no approach to
any similar drift-filled depression; in fact, where the depression
crosses the col, it is a conspicuous feature owing to the rocky ridge
above and below it, and it is difficult to understand why this con-
tinuous tract of drift-covered ground occurs here, except on the
supposition that a valley lies below. If the possibility of the
existence of the gorge be admitted, there is no difficulty connected
with the introduction of the drift, for the locality is just beneath the
ereat cwm on the west side of Snowdon, which must have been the
gathering-ground of a large glacier, and also lies below the drift-
covered tract on the upland plateau on which Maen Bras stands.
There is another remarkable feature which requires explanation, but
which is readily understood if it be supposed that a drift-filled valley
exists here. ‘T’o the south-east of Llyn-y-gader is a peaty moor, which
slopes gently to the watershed separating the Gwrfai from the
Colwyn. Viewed from the detached mass known as Pitt’s Head, the
watershed appears as a level line, and is apparently composed of an
alluvial deposit. It strikingly resembles one which one of us has
previously described at the head of Wet Sleddale in Westmoreland
(Got. Maa., Dec. 1V, Vol. I, p. 539), and as in the case of the Wet
Sleddale watershed, may be accounted tor on the supposition that
56 J. E. Marr and R. H. Adie—The Lakes of Snowdon.
a valley was here stopped up by ice, and partly converted into a lake,
which became largely silted up with sublacustrine detritus. The
bed of the Colwyn runs over drift until within a short distance of
Beddgelert. It will be seen, therefore, that a continuous line of
drift-covered tract can be traced from Nant Mill, past Cwellyn and
Llyn-y-gader, for a distance of about four miles. If the drainage
has been reversed between the present head of the Gwrfai and Nant
Mill, the curious course of the stream from Llyn-y-dywarchen will
be accounted for. This stream runs a little east of south into Llyn-
y-gader, whilst the Gwrfai issues from that lake in a general.
northerly direction, whereas if the waters of the Cwellyn and Llyn-
y-gader depression originally drained southwards, the Llyn-y-
dywarchen stream would then have proved a normal tributary to
the river once occupying that depression.
We may now pass on to the consideration of the upland tarns and
lakes. The four tarns on the west side of Snowdon may be dismissed
in a few words. The late Professor Ramsay speaks of them as
follows: ‘The lake called Llyn Ffynnon-y-gwas is possibly
dammed up by moraine matter”; and again, “a minor moraine
encircles Llyn-y-nadroedd on the north and east, and another
beautiful small one made of angular blocks and stones, now covered
with vegetation, bounds Llyn-goch on the west and south-west, while
a third dams up Llyn-glas.” None of these lakes, then, can be
claimed as resting in a rock-basin, nor can the drift-stopped tarn
below Moel Hilio (Llyn Cwm Dwythwch) be asserted to rest in
a basin of that nature. The lakes lying to the north-west of the
main Snowdon ridge merit a fuller description. Below the precipice
Clogwyn du’r Arddu, lies the little Llyn du’r Arddu at a height of
1,900 feet above the sea. The extensive moraine which blocks it up,
and extends far down Cwm Brwynog in a series of concentric semi-
circles, is admirably described by Professor Ramsay. The exit to the
west is between the great drift dam and solid rock ; the latter is well
rounded with striz running parallel to the stream, and the rough
sides of the roches moutonnées face westward. On them rest sub-
angular perched blocks, whilst the innermost crescent of the drift-
dam consists of angular blocks, as though some at least of this
material was rather of the nature of snow-slope detritus than true
moraine. It is quite clear that the course of the stream before the
lake was formed cannot have been as it is now, otherwise no lake
would have been produced ; it must have run in a more northerly
direction, but this former valley is now completely buried beneath
gigantic moraine-mounds for a long distance. We call attention to
this, as we shall have occasion to recur to the point when describing
the exit of Llyn Llydaw.
The water of Llyn du’r Arddu is of a deep indigo tint, a colour
not represented in Forel’s scale of lake-colours. It is popularly
asserted that the colour is due to the presence of copper in the water ;
but we are not aware that any analysis has been hitherto made to test
this. Old copper-mines exist close to the lake, but as one of us has
been unable to find any trace of copper in the lake-water, it would
J. EH. Marr and R. H. Adie—The Lakes of Snowdon. 57
seem that the colouring is not caused by the presence of this sub-
stance. The same may be said concerning the waters of Glaslyn
and Llyn Llydaw, which have also yielded no trace of copper.
Cwm-glas is the next hollow which contains lakelets, and these
have been specially noticed by Mr. Watts. He states that there can
be little doubt that the upper lakelet “is a portion of a bending
valley dammed at both ends by scree- and stream-débris, and thus
compelled to find an escape over the rocky side”; and that in the
rainy season the lakelet finds ‘‘a second outlet over the long, low
col to the east, so that in this state it has the two outlets depicted
in the six-inch map.” We here find a missing link in the series
of lakes leading up to those whose outlet is permanently over solid
rock. One of us has described Hard Tarn on Helvellyn, a lakelet
which strikingly recalls this tiny lakelet on Snowdon, being, like
it, situated on a shelf formed by a dip slope between two escarpments
(Quart. Journ. Geol. Soc., vol. lili, p. 13). In the Helvellyn pond,
the normal outlet is over drift, whilst the wet-weather outlet is over
solid rock; in the Cwm-glas pool, the normal outlet is over solid
rock, and the wet-weather one over drift, for the drift has accumu-
lated to a greater extent than that at the end of Hard Tarn. The
next stage in the Cwm-glas pool will be the complete stoppage of the
eastern exit over the drift, when the pool will drain permanently
and in all weathers over the solid rock. :
The lower pool of Cwm-glas is stated by Mr. Watts to be
“certainly confined in a rock-basin, as rock occurs at its actual
outlet, and at every point where any former outlet might have
been possible. The lake is, however, so shallow that its occurrence
in a basin of rock is perhaps of little consequence.’ We had
hoped to obtain soundings of this lake, but owing to the quantity
of floating ice, were unable to do so, although as the bottom
is everywhere visible, there is probably no spot where the depth
reaches six feet. We could not satisfy ourselves that the pool
occupied a true rock-basin. The stream issues from the lake with
a bank of solid rock at each side, but the stream is some feet in
width here, and its floor strewn with boulders, and a former ravine
six or more feet in depth might readily be blocked by detritus
at this point. We do not, however, believe that this is the case, for
just east of the present exit a drift-filled depression is seen, which
runs parallel to the existing stream, and joins it about 150 yards
below the exit, at a level far below that of the lakelet. The col
in this drift-filled depression is about 15 yards north of the exit, and
there we found a width of about five yards across from obviously
live rock on either side. It is true that large blocks of stone here
extend right across, but they do not seem to be in siti, for the
cleavage planes run in very different directions in the different
blocks. It was easy to bury a walking-stick up to the handle
at several points along this depression, and in other cases the stick
was prevented from penetrating by coming in contact with obvious
boulders which were movable. ‘his pool, like the upper one, is
situated on a dip slope shelf between two escarpments, and the ice
58 J. E. Marr and R. H. Adie—The Lakes of Snowdon.
has merely rounded off the edges of the escarpments without altering
their general character. It has acted like sandpaper, and there is no
indication of such erosion as would produce a rock-basin,—quite the
reverse. ‘The same feature may be noticed in the case of Sprinkling
Tarn on Scawfell. ;
The last cwm which contains lakes is the magnificent one east
of the summit of Snowdon. The lowest lake, Llyn Teyrn, is
shallow, and the stream from it flows over drift for a long distance
below the exit. Near this tarn, and close to the path, a glaciated
rock shows intercrossing striz, one set running east and west and
the other about 30° E. of N. and 30° W. of 8S. A better example of
intercrossing is seen by the path bordering the shores of Llyn
Llydaw, due west of the causeway. A roche moutonnée shows three
sets of striations—one trending H. and W., another 8.W. and N.E.,
and the third 85° W. of N. and E. of 8. These directions point
respectively to the top of Snowdon, the Lliwedd cliffs, and the cliffs
immediately above the roche moutonnée, and were probably produced
by glaciers coming from those directions at different times. We call
attention to them to emphasize a difficulty which has often been felt
if one assumes that glaciers can carve out rock-basins and yet are
unable to obliterate the strie formed at other times. Mr. Kendall
has, however, shown that the same mass of ice produces intercrossing
strie; also, we are aware that glaciers, like rivers, must be under
conditions more favourable for erosion at some times than at others ;
the difficulty is, therefore, by no means insuperable to those who
maintain the power of ice to form rock-basins, but still we think it
is a difficulty.
Mr. Watts writes :—‘‘Immense quantities of moraine material
occur on the south-east side of Llydaw, but a careful examination of
the map shows that only two possible outlets exist—that now used
for the purpose; and a second which is occupied by bog resting
on moraine, and gives rise to a small stream which is joined lower
down hy the outlet of Llyn Teyrn. The moraine is, however, only
a thin skin on the surface of the rock. The present outlet shows
live rock forty or fifty feet below the level of the lake, and the
second possible exit at a rather less distance below the same level.
If the moraine were stripped off, there is little doubt that this
lake . . . . would show a basin of rock which would hold
water, unless it is very much shallower than is generally supposed to
be the case.” It is very desirable that accurate soundings of this
lake should be made; indeed, we wish someone would do for the lakes
of North Wales what Dr. Mill has so admirably performed in the
case of those of English Lakeland. Mr. Watts’ observations would
permit the existence of a lake forty feet deep, which is not situated
in a rock-basin, and our observations lead us to believe that a very
much greater depth of water may be here held up by drift. A great
moraine runs right across Llyn Llydaw near the present outlet. It
is seen rising into high hillocks on the north side of the lake,
projecting as islets from the lake itself, and covering much ground
on the south side below the exit. No doubt it is, as Mr. Watts says,
J. LE. Marr and R. H. Adie—The Lakes of Snowdon. 59
a thin skin on the surface of the rock in many places. Rock, as he
states, occurs in the stream which comes from the lake at a distance
of forty or fifty feet below the exit, but the left bank of the stream
is bounded by drift for a long way beneath this, and the stream is in
places obviously cutting between drift and rock; nevertheless, we
do not believe that the old exit was here. Viewed from above,
a depression is seen running diagonally across the moraine-covered
ground between the two streams mentioned by Mr. Watts, and this
depression is marked by some pools, one of which is of sufficient size
to be inserted upon the six-inch map. The depression joins the
stream south-west of Llyn Teyrn, and the first live rock seen along
this line occurs between Clogwyn Aderyn and Clogwyn Pen-llechen,
south of Llyn Teyrn, at a vertical distance of nearly 200 feet below
the level of Llyn Liydaw. The lesson taught by Llyn du’r Arddu
proves that a buried valley need not show any marked traces upou
the surface ; and we believe that, even though the greater part of
the moraine material forms a thin skin over the rock, a buried
channel runs in an easterly direction along the route we have
indicated.
The water of Llyn Llydaw is described by Professor Ramsay as
being “of a green colour, like some of the lakes of Switzerland,”
though the difference of colour between the waters of Glaslyn and
Llydaw did not appear to us to be very marked when we visited the
lakes in the early spring.
Above Llydaw lies Glaslyn, at a height of 1,970 feet above the
sea, and immediately below the great precipice surmounted by
Y Wyddfa, the highest point of Snowdon. The tarn is very in-
structive. It is, as Mr. Watts remarks, “ bounded on all sides by
live rock, except at and near its outlet. This exit is over moraine,
which, however, is not very deep, for rock makes its appearance just
below, and in such a way as almost to compel belief in a complete rock-
bar. Besides the present course of the effluent stream is a parallel strip
of moraine running down towards Llyn Llydaw, but living rock soon
makes its appearance in this.” his parallel slip of moraine looks
quite insignificant when viewed from the path; but when visited
is found to be of considerable width. It joins the main stream at
a vertical height of at least 50 feet below the exit, and at the
junction a small stream is seen cutting its way backwards in the
drift. Between the exit and the junction of this . drift-filled
depression with the present stream is a waterfall, and the water has
here cut a mere groove in the rock. Moreover, we here meet with
a most significant feature: the bottom of the drift-filled depression is
at a lower level than the present stream, which runs at the side of the
valley, being separated from the lowest part by a low shelf of rock.
We here find a repetition of what one of us has previously noticed
in the case of the tarn Smallwater, near Haweswater in Westmore-
land (Quart. Journ. Geol. Soc., vol. xxi, p. 37), and we believe that
the explanation given in that case is applicable to Glaslyn also.
There is a feature of interest connected with the outline of the tarn.
A bay occurs on the north side, whose shore-line forms a curve
60 J. E. Marr and R. H. Adie—The Lakes of Snowdon.
parallel with those of the contour-lines above, where they run round
a little valley occupied by a small stream. ‘The existence of this
bay is, of course, explicable if the lake be drift-dammed, but
is difficult to explain if we suppose that it has been excavated
by ice.
The colour of the water of Glaslyn is indigo, though the tint is
not so deep as that of Llyn du’r Arddu. Here also copper-mines
have been worked close to the lake, but, as has been mentioned above,
no trace of copper was found in the water.
The samples, of which the analyses are appended in tabular form,
were obtained under somewhat different conditions in the case of
each lake. That from Llyn du’r Arddu was obtained from fairly
deep water, surrounded on the landward side by rock in sitd,
that of Llydaw from the middle of the causeway which has been
made across the lake, whilst that of Glaslyn was obtained from
shallow water close to an ordinary foreshore, consisting of loose
blocks and some vegetation.
ARDDU. LLYDAW. GLASLYN.
Parts per million.
-, ( Inorganic ie aes Abd 22 22 34
tolls Morea: ne 16 10 12
Hardness (Lime and magnesia salts) ae 22 20 22
Chlorine ee wee ea ee 9 9 12
Nitrogen as ammonia ... : Bes “004 004 a2,
re albuminoid ammonia . ee 026 “070 048
Oxygen absorbed in 15 min. beth wide “40 0 “40
4 hrs. aie o00 “40 80 1:20
Nitrog en as nitrates and nitrites ... Bh eALeD 16 “20
We did not think it necessary to determine the organic carbon and
nitrogen, as the above results may be generally used as a substitute
for them.
The analyses show that the waters of Arddu and Llydaw are
similar in character: they contain about the same amount and variety
of inorganic matter (chlorine, lime, etc.), but Llydaw contains rather
more than twice the amount of organic matter that Arddu does, as
shown by the albuminoid ammonia, and oxygen absorption in four
hours. The similarity of the amount of chlorine also suggests that
the organic matter is similar in the two cases. This result is what
would” be expected from the relative position of the lakes.
The results in the case of Glaslyn are very remarkable. The
amount of solids (not lime and magnesia salts) and chlorine, also of
ammonia (free and albuminoid), oxygen absorbed, and nitrogen as
nitrates, would always be held to indicate the presence of much
animal organic matter. This hypothesis seems at first ridiculous
from the position of the lake, unless the hotel on Snowdon summit
drains in any way into it. The only cther interpretation is, that the
sample obtained from near the bank was not of average quality.
No impurity of such character could be introduced in any ‘other way.
The object of these analyses, viz., to put to the proof M. Forel’s ~
hypothesis of the cause of coloration of mountain lakes, is unfor-
tunately not attainable from these results, owing to the peculiarity
Dr. Wheelton Hind—Carboniferous Life-Zones. 61
of Glaslyn, so that we must reserve this point for future work on
other lakes, further from possible contamination.
In the meantime, failing an analysis of peat water of the above
strength, there is some evidence in favour of the hypothesis from
the cases of Arddu and Llydaw, though we were not able to
match the indigo colour of these waters by means of his standard
solutions. We failed to find any trace of copper. On a future
occasion we hope to furnish more analyses.
In an article in Science Progress, new series, vol. i, p. 218
(1897), one of us describes some depressions formed on flat surfaces
of rock in the Lake District, owing to the more rapid weathering
beneath patches of moss, grass, and heather, which, when removed,
leave little basins beneath them; and it was suggested that small
lakelets might be produced in this way, especially in’ rocks
which contained much soluble material. The depression in question
occurred in the volcanic rocks of the Borrowdale Series. ‘l'o show
the effect of the weather upon rocks of this nature, a fragment of
rock (possibly hardened mud with volcanic matter) was extracted
from a peat-bog near Llyn du’r Arddu, and the analyses of the core
and of the weathered crust are given side by side :—
CORE. CRUST.
SiO, es Be 79:20 72-00
Ale O3 08 S00 16°74 22°36
He coo on6 1-96 2°55
Fe, O3 S60 B60 1-28 0°87
MnO a0 coe 0°34 0-41
Alkalies ... ooo 0°67 0-51
Loss on ignition B60 1-11 1°41
101°30 100-11
TIJ.—Novre on toe Lire-Zones oF THE CARBONIFEROUS DeEpostrs
or EUROPE.
By Wuretton Hinp, M.D., B.S. Lond., F.R.C.S., F.G.S.
T has long been a matter of reproach to British geologists that,
| with such a grand sequence of Carboniferous rocks as occurs in
Great Britain and Ireland, many of which are highly fossiliferous,
all attempts to establish life-zones in them have hitherto been un-
successful. As a subcommittee, appointed by the British Association,
has been put into existence to endeavour to zone the Carboniferous
rocks, it seems to me that a preliminary comparison with each other
of the life-zones already established in Russia and Belgium, and as
far as is possible to contrast the distribution of the zonal fossils with
that which obtains in Great Britain, may to some extent clear the
ground, and establish some important paleontological facts as a basis
for future work.
Russian geologists are able to state without any hesitation that
certain fossil forms are characteristic of certain zones in the Carboni-
ferous rocks of Russia, and that these zones are, with very slight
changes, the same for the Carboniferous deposits of Central Russia,
the Ourals, and the Donetz basin. Three main stages are recognized
62 Dr. Wheelton Hind—Carboniferous Life-Zones.
(with subdivisions and some small local variations), which are as
follows :—
Upper Zone :
Spirifer fasiger, Productus cora, Spirifer suwpramosquensis,
Conocardium Uralicum, Schwagerina princeps, Margini-
fera Uralica, with coal in the Donetz.
Mippue Zone:
Spirifer Mosquensis.
Lower Zone:
Productus giganteus, P. striatus, Chonetes papilionacea, with
coal-beds in Central Russia.
It is to be noted that in the Donetz basin the biological division
between the upper and lower divisions is not absolute, Spirifer
Mosquensis passing well up into the beds with Productus cora; but
it would appear that Spirifer fasiger, Keys, does not trespass into
the zone of S. Mosquensis, and the two fossils are never found
together.
A large number of widely distributed Carboniferous species are
common to all three divisions, but are not so frequent in the upper;
and this, in addition, coutains several forms which have never been
noted in Western Europe, but which, on the other hand, are
recognized as occurring in beds of the Salt Range period of India,
and in the Carboniferous beds of North America.
Passing to the Carboniferous beds of Western Europe, De Koninck
and Dupont are able to recognize three subdivisions in the calcareous
deposits of Belgium :—
Srace IJJ].—Urrer—
Visean (detrital): Zone of Productus giganteus, P. latissimus,
P. striatus, P. cora, Chonetes papilionacea.
Stace JJ].—Mippitr—
WaursortrAn(corallian): Ampleaxus coralloides,Syringothyris
cuspidatus, Spirifer striatus, Conocardium Hibernicum.
Stace I.—Lowrr—
Tournatstan (crinoidal) : Spirifer Tornacensis, S. cinctus,
S. laminosus, Syringothyris distans, Athyris Royssit,
A. lamellosa, Conocardium fusiforme, ete.
This threefold division, however, is not accepted by all Belgian
geologists. The Légende de la Carte géologique de la Belgique,
dated 1896, shows only two main zones in the Carboniferous Lime-
stone of Belgium—Visean and Tournaisian—the assise de Dinant,
with Chonetes papilionacea, being considered as a facies of the
Visean. The Waulsortian beds are placed as a facies of the Tour-
naisian, not typified, however, by any fossils ; and the assise of
Hastiére, with Spirifer Tornacensis, S. gluber, and Spiriferina octo-
plicata, is considered to belong also to the lower group.
Dr. Wheelton Hind—Carboniferous Life-Zones. 63
Gosselet (‘¢ Esquisse géol. du Nord de la France,” 1880) proposes
to divide the Carboniferous Limestone of France and Belgium into
ten zones, but, judging from the lists of fossils given, probably not
on palzontological grounds. He recognizes Spirifer Mosquensis as
occurring at horizons below that of Productus giganteus.
It will be noted at once that the highest stage of the Carboniferous
Limestone of Belgium is characterized by the same zonal form
(P. giganteus) as that which is so typical of the lowest division in
Russia, and that it is accompanied by P. cora, one of the zonal forms
of the highest Russian division.
Although, some time ago, De Koninck was of opinion that Spirifer
Mosquensis was found in the lowest Belgian (or Tournaisian) stage,
in his paper “Sur le Spirifer Mosquensis”’ (Bull. Mus. Roy. d’ Hist.
Nat., tom. iii, 1883, p. 873) he showed that he had confounded this
species with Spirifer Tornacensis and S. cinctus. In his remarks
on the affinities of the latter shell, he states ‘“‘qu’elle en différe
essentiellement [from S. Mosquensis] par sa grande taille, et, mieux
encore, par Pabsence dans sa valve ventrale des lamelles dentales
divergentes, si fortement développées dans celle de sa congénére
Russe.”
In a later work, De Koninck figures Spirifer spissus from Stage III
and S. suavis from Stage II, but these, judging from the drawings
alone, I should not, like to say were not varieties or specimens of
S. Mosquensis ; certainly they have much fewer ribs than the latter
species.
I have lately attempted to solve the question whether S. Mosquensis
really occurs in Great Britain or not. Originally Davidson figured
two specimens in his Monograph on the British Carboniferous
Brachiopoda (pl. iv, figs. 13 and 14) which agree very closely with
Russian examples. Later on he was led to doubt the correctness
of his determination through the influence of De Koninck’s work.
Unfortunately one of these figured specimens has disappeared, and
probably only that one remains which is in the collection of the
Royal Society of Dublin, but I have not been able to examine this
example.
In the Appendix to the Monograph Davidson figures two shells
from Scotland (pl. xxxiv, figs. 3 and 4) which closely resemble
S. Mosquensis in shape, under the name S. trigonalis var. bisulcata.
Dr. J. Young has kindly compared these shells with a typical
Russian example, and says that the Scotch examples have much
fewer ribs and that these are thicker.
I have, through the kindness of Professor Lloyd Morgan, examined
the shell from the Oracanthus bed of the Lower Limestone shales of
Clifton named S. Mosquensis by Stoddart, but this reference is an
error, the shells having nothing in common.
I have also examined a fine series of shells labelled S. Mosquensis,
from the Carboniferous Limestone of Co. Cork, in the collection of
the Geological Survey of Ireland, I recognize amongst them S. cinctus
and S. Tornacensis of De Koninck, but not S. Mosquensis. When
placed side by side the differences between these three species are
64 Dr. Wheelton Hind—Carboniferous Life-Zones.
very distinct, much more so than one would judge from the remarks
and descriptions of De Koninck. Both S. cinctus and S. Tornacensis
are more transverse, and possess fewer but thicker ribs, than
S. Mosquensis. The construction of the dorsal mesial fold and
corresponding sinus in the ventral valve is different in each species.
At present, therefore, I am unable to affirm the presence of
S. Mosquensis in Great Britain.
It is an important fact to note, in connection with the absence
of the Spirifer Mosquensis zone in Belgium, that Productus cora and
P. giganteus, the typical shells of the first and third zones in Russia,
should occur together in Belgium, and that, according to the Belgian
geologists, the beds with Productus cora are inferior to those with
P. giganteus. In the P. cora zone of Russia the fauna, taken as
a whole, is remarkably dissimilar to any that occurs in Western
Europe, especially towards the upper portion, most of the species
being entirely different.
The intimate study of De Koninck’s later monographs cannot but
convince the reader that with that author the erection of species was
largely secondary to the knowledge of the horizons at which the
various specimens were obtained. Starting with the preconceived
notion that there were at least three distinct molluscan faunas in the
Carboniferous Limestone of Belgium, he seized on the smallest
differences in detail or growth as a reason to invent a new species,
especially if it had been gathered from a special horizon. He says
himself (Ann. Mus. Hist. Nat. Belge, sér. Pal., tom. vi, p. 4): “Siaux
caractéres différentiels constatés entre des spécimens provenant
Wassises différents quelques faibles, qu’ils soient, vient s’ajouter une
constance bien établie, 11 me semble loisible d’admettre que ces
spécimens appartiennent 4 des espéces distinctes, et c’est ainsi que
je les considererai.” A very large number of the species which
De Koninck states are confined to one or other of his three horizons
in Belgium, I bave found together in the Carboniferous beds of
Great Britain and Ireland, and am inclined to think that many of
his species will be found to be merely synonyms.
In the voiumes on the Lamellibranchs of the Carboniferous Lime-
stone of Belgium, 461 species are described by De Koninck, not one
of which is said to occur except in one stage. The numbers are as
follows :—
Etage Viséen . . . . 222 species
aa. a \Wemllsorinens 3 6 UBS) 5,
1 LOUEMaISICniea area Ol mm.
461
The species of Brachiopoda also are supposed to have had the same
limited distribution, for not one of the 130 species described is
common to two stages; and out of 499 species of Gasteropoda
described only one species, and that with a query, is supposed to be
present in two horizons. Thus De Koninck would have it that there
are three absolutely distinct faunas, which never intermingle or
a
Dr. Wheelton Hind—Carboniferous Life-Zones. 65
overlap. However correct these facts may ultimately be shown to
be in Belgium, there is in the Carboniferous beds of Great Britain
and Ireland nothing at all comparable to such exactness in the
vertical distribution of the faunas of the Carboniferous period ;
and if one fact is emphasized more than another, it is that many
species of Brachiopoda and Mollusca reappear again and again at
various horizons, and survived throughout the whole of the epoch.
In Great Britain, Productus giganteus is a fossil very frequently
met with, and of very wide vertical range. In the Pennine area it
is met with in all the limestones from the Great Scar to the Crow
Limestone, thus passing from the base of the Carboniferous Limestone
to the top of the Yoredale Series. In Northumberland, it occurs
with P. cora throughout the whole of the rocks grouped by the
officers of the Geological Survey as the Carbonaceous division ; and
in Scotland is characteristic of the limestones of the Carboniferous
Limestone Series, both upper, middle, and lower divisions. In
North Wales, P. giganteus passes from the Middle White Limestone
of Mr. Morton to the top of the series, accompanied in the Middle
White and Upper Grey Limestones by P. cora, which shell is found
alone in the lowest member (the Lower Brown Limestone) of the
series. In South Wales, Mr. Morton finds P. giganteus and P. cora
in the limestones of Gower, and Mr. Stoddart records both these
fossils in the Carboniferous Limestone of the Bristol district.
Mr. Stoddart published (Proc. Bristol Nat. Soc., new ser., vol. 1,
18746, p. 318) a very careful account of the various beds of the
Lower Carboniferous Shales and Carboniferous Limestone of the
Bristol Coalfield, and the fossils contained in them. ‘The majority
of the Mollusca and Brachiopoda are not, however, zonal forms, but
are found at various horizons in the Carboniferous series, both there
and elsewhere. M. Max Lohest, after going over the ground,
published a small pamphlet entitled “Sur le parallélisme entre le
Calcaire Carbonifére des environs de Bristol et celui de la Belgique ”
(Ann. Soc. Géol. Belge, tom. xxii, p. 7),in which he would establish
an almost complete identity between the Bristol and Belgian series.
This author recognizes zones indicated by A, B, D, H, F.
A. Beds with Modiola Macadamii and Avicula Damnoniensis, which
correspond with those of Comblain au Pont. Mr. Stoddart, however,
pointed out the close connection of the fauna of these beds with that
contained in the Marwood, Coomhola, and Moyola beds. —
B. This bed is a red crinoidal bed, with Spirifer glaber, 8. bisul-
catus (?), S. Tornacensis, and Spiriferina octoplicata, identified with
the lower part of the Tournaisian beds of Belgium; but, with the
exception perhaps of Spirifer Tornacensis, all the other fossils are
found in the zone of Productus giganteus, if not near Bristol, in the
topmost beds of the Carboniferous Limestone of Derbyshire and
Yorkshire. M. Lohest says: ‘‘ Le base du terme B parait bien étre
Péquivalent de notre assise 4 Spirifer glaber; les schistes du sommet
représentant nos schistes a Spiriferina octoplicata”; but in Great
Britain both these forms are most abundant in the upper part of the
Carboniferous Limestone.
DECADE IY.—VOL. V.—NO. II. 5
66 Dr. Wheelton Hind—Carboniferous Life-Zones.
D is a bed of crinoidal limestone.
EB is a bed of dolomitic crinoidal limestone.
F is a thick oolitic limestone, which is considered to correspond
with the base of the Viséan, with Productus cora in the lower part
and P. giganteus above.
In this succession, Dupont’s Waulsortian division of Belgian rocks
is entirely absent, and the chief features on which the identification
of the two series of beds is based are purely petrological, and not
paleontological. There are so many horizons at which beds of
crinoids occur, that unless species can be recognized, such statements
are utterly valueless for the purposes of identifying horizons.
The Avon section shows the following sequence :—
Zone of Produetus cor’ ( Mountain Limestone, 2,000 feet.
and P. giganteus
Prod ucius gaganigus amd Lower Limestone Shales, 500 feet.
P. cora absent
Tn a paper published in the Annales du Soe. géol. de Belge, tom. ix,
1881-2, p. 31, De Koninck, describing some new Cephalopoda from
the Carboniferous Limestone of Ireland, gives three lists of fossils
which he considers as typical of the three series of beds established
in Belgium by Dupont, and states that he is able to make out the
same three zones in Ireland from the study of specimens in various
museums and collections. He considers that the following parallels
occur : —
TRELAND. BELGIUM.
1. Limestone of Armagh. Caleaire des Ecaussénes et
de Comblain au Pont.
2. Caleareous schist of Hook Point. Calcaire de Tournal.
3. Limestones of Rathkeale and Calcaire de Waulsort.
Co. Limerick.
4, Limestones of Cork, Dublin, Calcaire de Vise.
Galway, and Meath. :
If a comparison be made between the lists of Carhoniferous fossils
from these districts which were drawn up by the late Mr. Baily for
the Memoirs of the Irish Geological Survey, it will be seen at once
that no such paleontological divisions can be shown for the Irish
Carboniferous beds. Indeed, most of the species on which
De Koninck relies for the identification of his three life-zones are
not confined to the horizons which he mentions. For example,
Zaphrentis cylindrica, Syringothyris distans, Spirifer laminosus, Athyris
Royssit, A. lamellosa, and Orthis Michelin are said to be characteristic
of the Tournaisian; but in-Great Britain and Ireland these shells are
found to have survived all through the deposition of the limestones,
being not at all rare in the upper beds. ‘The fossils of the middle
zone are equally associated with those of the upper and lower in
British localities, while Productus giganteus and P. cora are by no ©
means confined to the upper beds. For example, P. giganteus occurs
at Hook Point in the Lower Limestones with Syringothyris cuspidatus,
Dr. Wheelton Hind—Carboniferous Life-Zones. 67
Spirifer striatus, S. laminosus, Orthis Michelini, Conocardium fusiforme,
Athyris Royssii, and Ampleaxus corolloides. At Armagh, Productus
gigauteus occurs at twenty-five different localities, at one of which it is
known tooccur with Orthis Michelini, Spirifer laminosus, and Zaphrentis
cylindrica; in fact, unfortunately for De Koninck’s rapid generaliza-
tions, Productus giganteus occurs in all the Carboniferous districts of
Ireland, and seems to have survived from the deposition of the Lower
to that of the Upper Limestones. Although copious lists of fossils
and localities are accurately given in most of the Memoirs of the
Geological Survey of Ireland, it is a great pity that those who had to
produce tbem did not see fit to arrange the lists of fossils according
to the horizons, instead of only giving localities, and leaving it to the
student to identify the horizon of each locality by a reference to the
colour which is shown on the map at each place. In the Memoirs
of the Scotch Survey, and the later English one, the reader is able to
see at a glance not only the locality, but the actual horizon whence
each fossil was obtained.
It would therefore appear that in Great Britain the zone of Pro-
ductus giganteus is very largely developed. In the Southern Pennine
district this fossil characterizes the beds from the base of the Lower
Scar Limestone to the Upper Limestone (the Crow) of the Yoredale
group. In Scotland, however, and, to some extent only, in the
Pennine and Bristol areas, this extensive zone is preceded by a series
of rocks in which this fossil is absolutely wanting—the Calciferous
Sandstone Series, which are probably represented only by the base-
ment beds of the Ingleboro area and the Roman Fell beds further
north. It is difficult to suggest a zonal form for this series, much
of which is non-marine; but on the Fifeshire coast Sanguinolites
Abdensis, Etheridge, and Schizodus Pentlandicus, Rhind, seem to be
confined to the series; and Modiola Macadamii is characteristic of the
Lower Limestone Shales of Bristol and the Coomhola and Moyola
beds of Ireland.
The shales overlying the limestones in Derbyshire and Yorkshire,
I have shown to contain a fauna totally distinct from the Carbon-
iferous Limestone and the Yoredale beds of Wensleydale (Gnot.
Maa., 1897, Dec. IV, Vol. IV, pp. 159-169 and 205-213). This
series, mapped by the officers of the Survey as Yoredale beds, may
be described as the zone of Aviculopecten papyraceus, Gastrioceras
carbonarium, Posidoniella minor, and P. levis, and includes the
Lower Coal-measures or Ganister Series, Millstone-grits, and shales
below them; while the Coal-measures may well be subdivided
into the upper, or zone of Anthrucomya Phillipsii, and lower, or
zone of Naiadites modiolaris, with many local horizons at which
only certain fossils have as yet been known to occur.
The following table gives the equivalents of these zones in
England, Scotland, and Ireland, from above downwards :—
68
Dr. Wheelton Hind— Carboniferous Life-Zones.
1: Zone of Anthra-
comya Phillipsi.
2. Zone of Naiadites
modiolaris and
Anthracomya
modiolaris.
3, Zone of Aviculo-
pecten papyra-
ceus, Gastrioceras
carbonarium,
Posidoniella
levis, and P.
MANO?»
4. Zone of Pro-
ductus giganteus
and
Productus cora.
5. Zone of Modiola
Macadamiz.
ENGLAND. ScoTLAND. IRELAND.
Upper Coal-measures | The Red Beds of Fife- | ? Wanting.
of Lancashire, York- | shire. ‘
shire, Staffordshire,
Bristol, including the
Spirorbis Limestones.
Middle Coal-measures
universally.
Ganister Series.
Millstone Grit.
Shales below the Mill-
stone Grit universally.
The Carboniferous
Limestone of Derby-
shire.
The measures from the
Great Scar to the Main
Limestone, N. York-
shire.
The Carbonaceous
Division of North-
umberland.
Carboniferous Lime-
stone of Wales and the
Mendips.
The Lower Limestone
Shales of the Mendips
and South Wales, with
several fossils common
to the Old Red Sand-
stone Series and the
Carboniferous.
The Red Beds of Fife-
shire.
? Wanting.
Norr.—Aviculopecten
papyraceus is said to
be found some distance
above the Ell Coal in
the Wishaw district,
Lanarkshire; but Ihave
'| never seen this fossil in
any Scotch collection,
and the determination
is possibly erroneous.
The Carboniferous
Limestone Series of
Upper
Scotland , Middle
Lower.
The Calciferous Sand-
stone Series, with Schi-
zodus Pentlandicus and
Sangquinolites Abdensis
inFifeshire,andafauna
very different from the
English and Irish equi-
valents. Mr. Kirkby
states that Productus
cora is contained in the
upper 500 feet of these
beds.
Coal-measures.
Castlecomer,
Leinster Coal-
field.
Coal - measures
of Fynes, co.
Limerick.
The Upper
Limestone,
The Calp.
The Lower
Limestone.
The Coomhola
and Moyola beds,
forming a pas-
sage from the
Old Red to the
Carboniferous,
and containing
certain fossils
common to both.
Series 1-8 constitute what I consider to be the “‘ Upper Carbon-
iferous,” and series 4 and 5 the ‘“ Lower Carboniferous,” of my
paper on the Yoredale Series (Grou. Mac., April and May, 1897).
While the zone of Productus giganteus corresponds to the Viséen of
Belgium, the lower zones of Great Britain do not resemble the
W. M. Hutchings—Rocks of Great Whin Sill. 69
Waulsortian or Tournaisian in their faunas. My own view, from
a comparison of the Belgian and British fossils, is that the zone of
P. giganteus in Great Britain and Ireland corresponds to the whole
of the Belgian series; for none of the fossils which are relied upon
by MM. De Koninck and Lohest to identify the lower beds in
both areas are in Great Britain and Ireland confined to the Lower
Limestone Shales, but are found in abundance, and in a full condition
of growth, at the top of the zone of P. giganteus.
The faunas contained in the beds of shale differ markedly from
those contained in limestones, the shales being much richer in
Lamellibranchs and Crustaceans, and comparatively poor in Brachio-
pods and the Actinozoa. Consequently the faunas of the same zone,
taken as a whole, vary very much according to locality and the
nature of the sediment. Consequently the zone of P. giganteus in
Scotland, in which the limestones are separated by thick beds of
shale, contains a very different fauna from that which obtains in the
same zone in Derbyshire, where the shales are practically absent,
and the limestone exists in one mass, made up of beds of various
lithological characters.
IV.—Twe Contact-Rocks or tHe Great WHIN SILL.
By W. Maynarp Hurtcutnes, F.G.S.
N what follows, it is proposed to give a general description of the
effects of contact-metamorphism, observed in the rocks altered
by the intrusion of the Great Whin Sill in Durham and Northum-
berland.
The work, of which this is the condensed result, has been carried
on for the last four years in the microscopical, and to some extent
chemical, study of a large series of specimens collected at many
points along the course of the Whin Sill exposure by Mr. E. J.
Garwood, and also, to a very much smaller extent, by myself.
Mr. Garwood has been for a long time engaged in a detailed
examination of the geology of the district, and will in due course
publish the results of his work, which is not yet complete. It was
at his suggestion and request that I undertook the petrological study
of the specimens collected.
As is well known, the rocks into which the Whin Sill mass has
been intruded consist mainly of limestones, shales, and sandstones
of the Lower Carboniferous beds. The special interest and value
of the contact-effects here displayed, are enhanced by the fact that
the rocks acted upon were all in what may be called a perfectly
simple and elementary state. We know exactly what they were
like before they were altered by the intrusion, and can study them
as fully as we wish, in their original and normal condition, in the
same and other districts. Thus, the shales, the metamorphism of
which gives us the most interesting portion of the material, with
the most important bearings upon the question of contact-action in
general, are in all respects counterparts of those from the Coal-
Measures and the Lower Carboniferous, which I have described in
70 W. M. Hutchings—Rocks of Great Whin Sill.
full detail in previous papers in this Magazine. None of the rocks
affected had undergone any sort of “‘development” previous to the
intrusion of the Whin; and as they have not been in any way
changed, except by weathering, since the consolidation and cooling
of the igneous mass, we are able to see with considerable certainty
just what mineralogical and structural changes are to be ascribed to
contact-metamorphism.
Such comparatively simple and reliable conditions, in a contact-
area of such importance, are so very rare that it is at once apparent
how valuable are the indications we may derive from them, and
how great is the assistance they may render to us in our endeavours
to understand the much more complex cases usually presented to
us. I say “in a contact-area of such importance” because, as
I shall show, we have here exactly reproduced for us a large portion
of the phenomena we are accustomed to see round the intrusions,
on a much mightier scale, of granite, etc. It makes no difference
that in greater contact-areas the mineralogical and structural details
are more striking as to size, so long as on the smaller scale they are
equally clear and distinct.
I propose to deal with the altered rocks in the following order :
pure or almost pure limestones, argillaceous limestones, shales,
calcareous shales, sandstones. These, however, pass over into one
another in all degrees, and there is, of course, no sharp division
between limestones, argillaceous limestones, calcareous shales,
shales, quartzy shales, argillaceous sandstones, and sandstones or
grits. It is among some of the intermediate rocks that the most
interesting effects are produced.
When a sufficiently large number of specimens had been sliced
and examined, it became evident that there was no use in
multiplying them beyond a certain point. It was clear that the
same results of alteration could be found at intervals all over the
long course of the Whin Sill, wherever the chemical nature of
the invaded rocks was the same. For this reason, in the following
descriptions, particular localities of occurrence will only be men-
tioned when specially interesting or pronounced developments have
taken place, which are qualified to serve as good types of the
alterations in general.
Commencing, then, with the limestones, we find that when these
are pure, or at all events are non-argillaceous, the action of the
Whin Sill upon them has been limited to a recrystallization of them.
In some cases this recrystallization is very finely marked, and may
stand alongside of the “marmorization” of similarly pure lime-
stones by intrusions of granite.
Whether interfusion has taken place to any extent between the
Whin and the purer limestones, at some points, is a question which
it is not possible to answer decisively. In many actual contact-
slides examined there does not seem to be evidence that any such
action has occurred at all; the division line is quite sharp and clear,
the Whin is small-grained but quite crystalline right up to the
junction, and the recrystallized limestone begins equally sharply on
W. WM. Hutchings—Rocks of Great Whin Siil. va
the other side of it. If there be recrystallized quartz, this also often
comes quite sharply up to the contact-line.
_ In some instances there does appear to be a very narrow streak of
more indefinite matter, possibly denoting interfusion ; and there are
other cases where a very noticeable band is seen of what has clearly
been of a tachylitic nature; though whether we ought to regard it
as a true tachylite,—i.e. a product simply of rapid cooling of the
edge of the molten igneous rock,—or whether it is more a result of
interfusion, I think cannot be settled, because chemical analysis
would not here give a sufficiently definite answer. So far as
microscopical evidence can help us, I rather incline to the view that
it points to interfusion having taken place to some extent. Thus,
the most striking example is one from Middleton Wood, near
Belford. In the hand-specimen the tachylitic material was some
two inches thick, and in the slide prepared from it, over the line of
contact, there is nearly half an inch of it. The limestone is simply
crystallized, as is also silica which it contained. It has not had any
new minerals formed in it, but quite close to the junction there are
a few colourless garnets, just a narrow string of small crystals and
grains. ‘Then comes the tachylitic band, mainly a yellow to red-
brown glass, with a good deal of indefinite, speckly, felsitic-looking
matter, and chloritic decomposition products, but with some felspars
and augites of good size dispersed in it, and a few prisms of
enstatite. With these is also a good deal of garnet in small grains,
and at some parts patches of it of much larger size. As no garnet
occurs in the altered limestone except at the actual contact, and as
it occurs in the tachylitic band, it seems likely to be a product of
the interaction of limestone and Whin. No garnets seem ever to
occur in the normal Whin Sill rock.
In some other specimens examined there is, again, a narrow band
of what appears to be another product of such interaction. There
is a seam of what appears to have been tachylitic, now very much
obscured by calcite and chlorite due to decomposition. The lime-
stone is perfectly free from any new mineral formation. But on the
side towards the Whin comes a zone of close-grained igneous rock,
a narrow strip of which is coloured brownish-red of a peculiar
shade. Under higher powers it can be made out that this reddish
band contains swarms of minute flakes of mica, and that it is from
these that it derives its colour. Here and there the compact swarms
of this mica open out, and become more scattered and larger in size,
some individuals being seen as fairly well-bounded crystals, which
can be recognized as a deep brown-red very dichroic biotite, some
of the best flakes giving a good optic figure in convergent lght
with 54; inch objective. None of this mica is ever seen in the
normal Whin, and I have not seen any signs of it except at contacts
with pure limestones. It certainly appears to be an endomorphic
formation in the igneous rock, brought about by interaction with the
limestone, though it does not seem easy to explain the chemical re-
actions which have been concerned in it. 1 do not recollect any
mention of a similar result on an intruded igneous rock, and have
Certainly never seen it myself in any other case.
72 W. M. Hutchings—Rocks of Great Whin Sill.
We will now pass on to the altered argillaceous limestones,
including under that head all such rocks as are still safely to
be recognized, microscopically and chemically, as having been
dominantly limestones, but which have contained sufficient shaly
material to provide a noticeable amount of silica and alumina, with
some alkali and magnesia, which latter will also be present, more
or less, in any case, in most of the limestones. Rocks of this class,
of varying degrees of admixture, occur at many points along the
Whin Sill, and have given rise to very interesting contact-products.
The new minerals formed are garnet, augite, idocrase, wollastonite,
epidote, hornblende, felspar, chlorite, sphene. The garnet is the
most persistent, being seen in all the slides examined from rocks of
this class, whereas most of the above minerals may be present in
some cases and absent in others.
One or two typical examples will serve to give a general idea
of the nature of the alterations produced. Thus, from specimens
of not very impure limestones from Burtreeford, sections have been
cut which show the actual contact-line. First comes a narrow band
(about 345 inch) which seems to mark some sort of interfusion.
Thongh now much obscured by fine-grained secondary calcite, it is
distinctly defined both on the side towards the Whin and on that
towards the limestone. The Whin is very fine-grained, but contains
a good many perfectly fresh and distinct crystals of felspar of
larger size. Occasionally one of these crystals projects just into the
edge of the interfusion-band, and may be seen to have been melted
away in it and left with a rounded end.
Along the edge of the band towards the limestone lie many small
but good crystals, and some irregular grains, of idocrase. The
largest crystal in these particular slides is a prism <5 inch long by
i30 inch wide, very fresh and perfect. A very few lie also a little
further in, but none occur at any distance from the contact-line.
It is interesting to note the mode of occurrence of these crystals,
some of which are completely bedded in quartz, some again in
calcite, and others in grains of calcite which are surrounded by
quartz.
Then comes another narrow zone, about -2; inch, which consists
largely of recrystallized quartz as a sort of ill-defined mosaie,
intermixed with varying amounts of calcite. This quartz is all full
of inclusions of small garnet grains and indeterminable microlites,
and clearly dates from the original metamorphism of the limestone
by the intruded Whin, being strongly distinguished from later
quartz which has filled in small cracks, etc., and which contains no
such enclosures. This quartz band passes abruptly into coarse-
grained, highly crystalline, saccharoid limestone, the calcite crystals
containing numerous small garnets in rounded grains. A deep-
coloured, very dichroic sphene, in good-sized crystals and grains, is
also present.
Rather more impure limestones are represented by specimens
from Rumbling Churn, near Dunstanburgh. Garnet is again very
abundant, mainly in very small crystals and rounded grains
W. M. Hutchings—Rocks of Great Whin Silt. 73
averaging about y5s5 inch in diameter, but in some cases reaching
+t inch and a little over.
At some parts of the slides these garnets are packed so close that
scarcely anything else is visible. They vary from colourless to
yellow and greenish, and some are a rich red-brown. Often the
centre is coloured, and the outer rim is colourless. Augite occurs
plentifully with the garnet, in good-sized crystals and large irregular
complex grains. It is all perfectly fresh, and some of it is of a very
decided green colour, and slightly dichroic. Both garnets and augite
come right up to the contact-line, and in one slide may be seen lines
of very small augite crystals, clearly of contact-origin, growing out
from the edge of the Whin, like the teeth of a saw, into the lime-
stone. A very pale hornblende in slender needles is also present at
some parts; epidote and sphene are well represented, and there is
a good deal of recrystallized quartz, which frequently encloses garnet
and augite. The remaining calcite of the limestone is completely
recrystallized. There are often large fields of one uniform grain of
it, with numerous garnets and augites contained in it.
In the mosaic of recrystallized quartz in these highly calcareous
rocks one may often suspect felspar to be present, but without being
able to make sure of it, owing to «absence of cleavages and the
impossibility of making reliable optical tests. In one specimen from
near Dunstanburgh, however, an altered limestone shows numerous
small crystals, together with more or less irregular grains, of well-
cleaved fully-individualized felspar. Some few of the crystals even
allow of identification, with much safety, as anorthite or a closely-
allied species (sections with parallel cleavage, extinctions 30°-40°,
with emergence of good axial bar inside the field). They le in
amongst very coarse-grained recrystallized calcite, near the junction
with the Whin. It will be seen later on that some of the altered
shales contain abundant new felspar. The above specimen shows
also a few garnets, some epidote, a good amount of recrystallized
quartz, together with a considerable amount of wollastonite, mainly
in tufts and bunches of often sheaf-like, radiating fibres, with here
and there bits of sufficient size for the application of optic tests.
This mineral appears to be not of frequent occurrence in these
rocks. Indeed, it may be noted that, so far as concerns the lime-
stones which are reasonably free from any admixture except silica,
there seems seldom to be any reaction between the lime and the
silica. Calcite and quartz recrystallize side by side, and it is rare
to see in these particular rocks any formation of wollastonite, or of
any calcareous hornfels-like products, such as are more frequently
encountered round granite-contacts.
Sometimes there were little bands of sandstone in the pure lime-
stone, quite close to the contact. A specimen from near the Roman
station of Borgovicus, close to the Whin, is sliced so as to show both
recrystallized limestone, very saccharoidal, and sandstone converted
into a well-cemented quartzite, with some new felspar among the
interstitial matter. The division-line of the two products is very
elear and sharp, and there las not been a trace of action between them.
74 W. M. utehings—Rocks of Great Whin Sill.
It is not only close to contact that these limestones have been
affected. Complete recrystallization is seen at more than 60 feet
away, and small augite crystals are seen in a specimen over 40 feet
distant.
We may now turn to the consideration of the alteration-products
of the shales. These shales along the contact-area of the Whin
Sill have varied in nature in every degree, from argillaceous beds
almost quite free from quartz, to others in which that mineral ‘has
formed a large proportion. For our present purpose we will call
them all shales, speaking of them as more or less sandy, and only
draw the line where the quartz has increased so largely that we
must recognize them as argillaceous sandstones and classify them
accordingly. Of this class of rock a very large number of
specimens have been examined, but here again a few examples will
suffice to give a clear idea of the general lines on which the
metamorphism has proceeded. The intensity, and to some extent
also the character, of the alteration varies more or less at different
places. This is partly due to different composition, notably the
variation in the amounts of quartz and of alkalies contained affecting
the susceptibility of the beds to contact-action. Partly it is due
also to the varying bulk of the intruded rock at different points, and
sometimes we cannot account for the variation except by assuming
some difference in the local conditions of the invaded beds, as to |
temperature, degree of hydration, etc., before the intrusion occurred.
Outwardly the change undergone by the originally soft shales
consists in great induration, accompanied by more or less lightening
of colour. In the inner zones of action, nearer the igneous rock,
(sometimes also at considerable distances), the soft, fissile, dark-
coloured shale has been altered into a hard, compact, grey or
greenish-grey rock, with often very little fissility remaining, and in
many cases completely replaced by a conchoidal or almost flinty
fracture.
Inwardly, as revealed in thin sections, the most constant and
striking change lies in the production of new mica, with chlorite,
with a totally new structure as well as new mineralogical com-
position. Newly erystallized quartz is also frequently a main
feature, in some cases felspar has been abundantly produced, and we
have examples of the appearance of special contact-minerals in the
form of biotite. andalusite, anthophyllite, ete.
If we take first the purest shales, which have had little, if any,
quartz, and which have a chemical composition like that of some
of the purest “ fireclays,” we find that where the contact-action has
been most intense we have a complete recrystallization of the entire
rock, with formation of a new mass of white mica throughout.
Instead of the minute flakes of the indefinite micaceous mineral
which has been produced in the fireclay or shale, making its main
constituent, and lying nearly all in one plane, we get a network
of much larger, well-developed flakes and crystals of white mica, —
lying criss-cross in all directions. In many cases a good deal of it
is grouped together in fans and sheaves, and roughly spherulitic
W. M. Hutchings—Rocks of Great Whin Sill. 79
ageregates giving more or less black-cross figures in polarized light.
Intimately mixed and interwoven with this new mica is an
abundant chloritic mineral. This chlorite forms part of the sheaves
and spherulitic groups, and all over the slides is seen to have been
formed flake for flake with the mica, as a result of one and the same
process. No such chlorite exists in the unaltered beds; as I have
previously pointed out, both it and the white mica are the result
of a splitting-up and higher development of the impure and
complex micaceous mineral of the clays and shales. In some cases
there is a certain amount of biotite formed, with a similar mode of
occurrence, but this is not frequent among these rocks. The
formation of “ spots”? may also be seen on a copious scale in some
specimens; and these spots, though small, are exactly analogous to
the larger ones seen at some granite contacts, being due to the
agerevation of the chloritic material which is separated out during
the recrystallization of the rock constituents.
One or two special examples of the alteration of these pure
shales may be given in illustration. Thus, a specimen from
Rowntree Beck, taken 18 feet below the Whin, is very highly
altered but still contains good fossils. An analysis of it gives—
Siltcayy ess 600 Bas cs aah 51°40 per cent.
Alumina ... Re Be as ae 26°85 95
Ferric Oxide! ... ee ine 50 6°15 a
Lime Bae sare Bae Bao a8 0°56 59
Magnesia ... oC 568 565 se 2°38 5p
Potash mat BN ae Ma 5°21 1) Re
Sod te Umesh ate h ee (enema are veeer (OMe Ene a
W ater 6°45 9
100°78
This composition shows the rock to have been originally of the
nature of a fireclay, closely resembling some of the series of which
I published analyses in a former paper (Grou. Maa., 1894, Dee. IV,
Vol. I, pp. 36-45 and 64-75). 1t is now a muscovite-chlorite rock,
with abundant ‘‘ spots” all over it. Into these spots is concentrated
nearly all the pigmental matter of the rock, together with chlorite
and numerous dark grains and microlites, so that the spots are dark
in a light field. Parts of this field are almost clear and colourless.
In polarized light they are seen to consist of an interlacing mass
of muscovite and pale chlorite. Sheaves and spherulitic bundles of
mica and chlorite abound all over the section, and there is no sign
of any definite orientation of these minerals in any direction. The
entire rock is crowded with small grains and crystals of rutile re-
erystallized from the original ‘“‘ needles” of the shale.
Another interesting spot-rock comes from near High Force. In
ordinary light a section of it shows a sort of marking off into
roughly polygonal, or approximately circular, clear spots, framed in
1 Tn this and following analyses a// the iron is reported as ferric oxide, no special
determination having been made of the portion which is always present as ferrous
oxide. his often causes more or less excess in the totals, but is not of any im-
portance for the purposes for which these analyses were made.
76 W. M. Hutchings—Rocks of Great Whin Sill.
darker greyish and brownish pigmental matter. The spots are
mostly of a very pale greenish colour, and proper illumination enables
us to see countless flakes and crystals of a chloritic mineral. With
crossed nicols the whole slide is resolved into a network of
muscovite flakes, lying again in every possible direction, and amid
the brightly polarizing mass of this mica the chloritic spots are
more or less dark and isotropic. In‘some the transition from the
bright frame of mica is quite sharp; in others mica projects more
or less into the spot, and only the centre is free. Many spots show
a field of quite isotropic, pale-green substance, in among which a dim
and speckly fine-grained mosaic polarization is discernible. These
spots are again in all respects exact counterparts of what may be
seen at some granite-contacts. It is curious to observe that,
whereas in the previous example the dark pigmental matter has
concentrated inside the chloritic spots, in the present case it has
remained completely outside them, and is mixed in with the mica.
I have made no analysis of this rock, but it shows only a very
small amount of recrystallized quartz, and is no doubt very closely
the same in composition as the last. No trace of clastic muscovite
remains in either of these, and, indeed, in nearly all the highly
altered fine-grained shales examined, it has absolutely disappeared
and entered into the same complete recrystallization which has
affected the main mass of secondary micaceous and other material
of which the shales and clays were composed.
Perhaps among these very fine shales examined, the most interesting
case is shown in a specimen from near Winch’s Bridge, in Teesdale.
It is from a body of rock which has been caught up by the Whin.
It contains—
Potash ... ees ae ae eas 5°71 per cent. s
Soda eres 060 COO eae eos 1-49 ” jt 2p
Water ... ie ave ue ad 7°40
99
This is very nearly the maximum of alkali which I have found
in any of the carboniferous shales and clays. It can have contained
but little quartz. When it is examined under the microscope it
is seen to consist, to a very large extent, of the peculiar substance
which I have previously described in detail as being found in varying
quantity in so many altered rocks around granites (Gunon. Mae.,
January and February, 1894). I traced and described its various modi-
fications and developments, and endeavoured to show the probable
nature of its origin and the part it plays in the changes going on
during contact-metamorphism. There seems every reason to regard it
as a product of the so/ution, or “aqueous fusion,” of original materials
preliminary to recrystallization. Sometimes we see it in a quite
amorphous state. Its first stage of development from this shows
a faint minutely-speckly polarization. At very thin edges, with high
powers and suitable illumination, it is seen to be very finely granular.
We can see it in contact-slates in all stages of evolution, from —
the first appearance in it of very few and smal] mica-flakes, up to
a full development of new mica out of it.
W. M. Hutchings—Rocks of Great Whin Sill. 17
J alluded, in the paper referred to, to the fact that this substance
could be seen in the contact-rocks of basic intrusions, but in less
amounts than at granite-contacts. I had not at that time seen the
specimen we are now considering, which shows the substance in
greater amount than any other I have ever seen, and which
strikingly confirms the view at which I had arrived concerning
its origin and nature. It here forms a sort of base, or groundmass,
all over the slide, and is nearly colourless, there being very little
iron present. None of it is quite amorphous, but it has the speckly
minutely felsitic polarization. Mica has formed in it throughout,
but not regularly diffused, so that whilst at some parts there are
patches, large enough to fill the field of.a half-inch objective, in
which but a few small distinct flakes are to be seen, we have other
portions made up so entirely of mica that little of the base-substance
can be seen among it. We can trace the growth of the mica in
all stages. It is to a large extent in tufts and sheaves and rosettes ;
- many of these of all sizes, as well as single flakes and crystals,
and crossed and interlaced groups of them, may be seen brilliantly
polarizing, floating free, as it were, in the nearly amorphous material
out of which they have grown.
It is quite clear that what we here see is an intermediate stage,—
an interrupted development,—on the road towards some such final
product as the two examples we have just been studying. Had
the conditions suitable for the crystallization of the mica continued
long enough, we should have had a complete and uniform develop-
ment of that mineral, together with its attendant chlorite, as before.
But it is just the fact that the conditions did noé continue long
enough for completion of the process, which gives such particular
interest and value to this occurrence. Such interrupted cases, when
we can get them, are capable of teaching us more of what actually
“goes on” in these contact-metamorphisms than any number of
completed examples, where often all trace is lost of the steps by
which the final result has been arrived at.
The rutile of the altered shale has crystallized out in much larger
and more definite crystals than the original needles, many of them
as “hearts” and ‘kites,’ and the entire slide, mica as well as
base-substance, swarms with them. A good proportion of the mica,
in this case, is brown and strongly dichroic, especially some of its
larger tufts and sheaves. There is no clastic quartz remaining ;
what little there was evidently entered into the general process of
solution, and has reappeared as newly-formed mineral. It is also
interesting to notice how the numerous small zircons of the original
shale have resisted, as they so frequently do, the solution which has
destroyed all trace of everything else, and how they remain quite
unaltered among the new products.
The greater number of shales affected by the Whin Sill have not,
however, been as purely argillaceous as the above examples. They
have mainly been more or less sandy. But their alteration has
proceeded on much the same lines as those described, and it will not
be necessary to consider them in much detail. In some of the more
78 W. WM. Hutchings— Rocks of Great Whin Sill.
highly metamorphosed beds all original quartz has disappeared, and
has been replaced by newly-formed contact-quartz. Where the
amount of it is sufficient, we sometimes get a good “mosaic” of
the same nature as what we see so universally at granite-contacts.
Where there is less of it, we see it disseminated among the micaceous
part of the rock in single grains, and groups of grains. In less
intensely affected cases we get more or less clastic quartz remaining ;
sometimes it does not seem to have been attacked at all, and again,
we may be able to see various degrees of its attack and corrosion
by the processes of solution which took place. With the more or
less regenerated quartz we nearly always see that the argillaceous
position of the shale has given rise to just the same products as
those we have been considering, the mica and chlorite, the spots,
and the residual speckly substance, all appearing in the same
relationships as to individual forms and general structures.
Among these altered sandy shales, however, there are some
occurrences which are of such special interest that they must be
here alluded to, in connection with the review of the whole contact-
phenomena of the Whin Sill and their bearings on the general question
of contact-metamorphism. In a former paper (“An Interesting
Contact-Rock,” Gron. Mac., March and April, 1895) I gave minute
descriptions of the rocks to which I allude, and I would refer
students of the subject to that paper, limiting myself here to
a recapitulation of the particular points involved.
The principal rock in question is a bed of shale 8 feet thick,
at Falcon Clints. It occurs 75 feet below the Whin, a series
of limestones, sandstones, and shales intervening. It contains at
some parts large numbers of approximately spherical nodules like
peas. Thin sections show, in ordinary light, a grey groundmass
in which are bedded grains of clastic quartz. In polarized light
it is seen that this groundmass consists largely of an isotropic
substance, in which he numerous grains, rounded, irregular, or more
or less definitely-bounded, of newly-formed quartz and some felspar.
At parts these grains are so numerous and closely packed that they
amount to a true interlocking mosaic, with very little isotropic
matter. At other places they are more separated, and we get quite
large spaces of the isotropic substance, but containing small flakes
of mica and other things. These grains are not yet fully indi-
vidualized; they are not water-clear, and have still so much
dimness about them that they cannot be properly made out at all
except in polarized light. They are absolutely distinguished from
the original clastic material; not one of them could ever for a
moment be mistaken for anything but a newly-formed secondary
product.
The clastic quartz-grains remaining are seen to be all more or
less attacked and corroded by the surrounding groundmass ; their
original angular outlines are in nearly all cases preserved, but the
outer portions are no longer quartz, but an altered substance often —
containing a considerable amount of white mica and sometimes of
felspar, whilst in some cases anthophyllite and andalusite are seen.
W. M. Hutchings—Rocks of Great Whin Sill. 79
Tn the nodules considerable fields of clear, almost colourless, quite
isotropic material are seen, in which bundles and sheaves anil
pseudo-spherulites of felspar, with some quartz, have been formed.
Anthophyllite and andalusite are also seen in some of them.
Here, again, we have preserved for us one of those interesting
eases of interrupted development. All the finer-grained material
of the shale,—the impure micaceous mineral and the minuter quartz,
—has been taken up into solution, or aqueous fusion; and out of the
substance so formed a mosaic of quartz with some felspar, together
with muscovite, has been in process of crystallization. But this
process was arrested before it was complete, and so we are again
able to see the unfinished stages, to observe the residual indefinite,
isotropic, intermediate matter, and to note also the larger quartz-
grains which were being attacked and dissolved, and would have
all disappeared if the solution stage of the contact-action had been
able to continue somewhat longer.
Sections from other parts of this bed show us mainly a fine-
grained aggregate of newly-formed quartz and felspar, passing down
into a quite cryptocrystalline felsitic-looking mixture (adinole), but
opening up, on the other hand, here and there into numerous clear
and glassy patches, which in polarized light are seen to consist of
groups of well-twinned plagioclase felspar, which can often be
identified as albite, whilst the extinctions also point to the presence
of a species allied to oligoclase.
From the neighbourhood of Rowntree Beck, again, come specimens
of shale altered to adinoles, and showing nodules up to two inches
across, with anthophyllite.
We come now to the calcareous shales, and find that among
these we have some of the most intensely altered rocks of all.
Sometimes they occur as narrow bands in connection with purer
limestones, sometimes as patches and lenticular masses in such
limestones, and sometimes as thicker independent layers.
The most striking occurrence is at Falcon Clints. The specimens
show a compact hornfels-like brown rock, with a jaspery sort of
appearance and fracture. It contains many garnets of sufficient
size to be easily seen with the naked eye. ‘Thin sections show that
these garnets are the most prominent mineral contained. They
very much resemble those in the altered impure limestones round
the Shap granite, and like them are polysynthetic and show a good
deal of birefraction. They are, however, here not so often well-
defined crystals, but more irregular grains and patches. They are
often very much cracked, the cracks being infilled with chlorite
and other substances. They occur irregularly, some parts of the
rock being free from them and others containing swarms of small
grains and crystals.
In some specimens idocrase occurs with the garnet, some of it as
good large, well-defined crystals on which characteristic angles can
be determined. It is nearly all quite fresh and good, and in every
way of normal character.
Both garnet and idocrase crystals may be seen containing large
numbers of small crystals of spinel, the garnet much more so than
80 Helin Ha chings== Rocksloy Grea Waves am
the idocrase. No spinels are seen except as enclosures in those two
minerals. The greater portion of them are of a good deep-green
colour, and exactly resemble those seen in altered limestone of
bombs from Somma; there are also colourless and pale reddish-
brown crystals.
If we take several thin sections of specimens from this occurrence
and average, as it were, the results of microscopic examination, we
find that a large proportion of the rock consists again of a base or
groundmass, which varies greatly in its texture and fineness of
grain. Sometimes it is a close-grained, felsitic-looking mass, quite
cryptocrystalline, and nothing definite can be made out as to its
component minerals. At other parts it becomes coarser, and
examination with high powers seems to show that much of it is
quartz and felspar; this conclusion being confirmed when we come
upon good-sized patches, like glassy spots in ordinary light, which
with crossed nicols are seen to consist of well-twinned felspar
with sometimes more or less quartz, ‘This groundmass may be
described as a calcareous adinole. In it are bedded many new
minerals besides garnet and idocrase.
Wollastonite occurs at some parts in considerable abundance,
mainly as radiating sheaves and bunches, with sphene, epidote, and
recrystallized calcite. In some slides are well-developed chloritic
“spots,” as well as others of the pale yellow-green, almost quite
isotropic, granular matter; and there are some which appear to
be cordierite in early stages of development, corresponding exactly
with similar spots seen to occur together with undoubted cordierite
in other contact-rocks.
A large hand-specimen of this rock from Falcon Clints I have
analyzed. It contains :—
Silica Bite 206 bon 900 209 53°80 per cent.
Alumina ... ue 600 ak soo 20°25 Pe
Ferric Oxide ane sits sine or 8°15 ia
Lime see BOO 0 Be ais 3:27 AN
Magnesia ... 600 500 000 ace 3°02 a
Potashieeges. aes Bes ath aes 2°32 Nees
Soda ek ee ate Ana ado 6°54 i {8 Be
Water and Carbonic Acid ainsi base eit 2°90 50
100°25
Another occurrence of a similar calcareous adinole is found at
Sneblazes. A thin section shows the same sort of groundmass.
No garnets or idocrase appear in the specimen examined, but there
is a good deal of augite in small crystals, and felspar is again seen
here and there. ‘The analysis of this rock gives :—
Silica a6 oc Bae as ie 50°60 per cent.
Alumina es odd 4 coe 20°38 Ae
Ferric Oxide ah oot 8°30 “
Lime ae oe ae T:79d i
Magnesia ... : 2°58 i
Potash 2°39 6 6-75
Soda see Mili 136 ae \ f
Water and Carbonic Acid 3°80
W. M. Hutchings—Rocks of Great Whin Sill. 81
Another specimen of a like nature, from close to contact, near
to Crag Lough, Bardon Mill, has the following composition :—
Silica of O00 bic abe 609 48°20 per cent.
-Alumina ... ase a se Ae 17°30 Fe
Ferric Oxide See HR sais Boe 12°50 3
Lime Bs Ae ses ohh ah 10:08 as
Magnesia ... ee aus shi des PRAT / 30
ORS ooo bbe aes ae Se 1:93 Pe
Sats eRe Cte ih PE) iia js a
Water and Carbonic Acid isi sie 4:05 Bs
100°82
It resembles the others in general composition, but shows hornblende
among its new minerals.
It now remains to consider the sandstones, of which a large
number have been collected from different points. There is not
very much to be said about them, because when they are pure, or
nearly so, the alteration is limited to a compacting and conversion
of them more or less into quartzites; and where they are less pure,
the interstitial matter has undergone the same alterations as have
been above described. Thus, where there has been any noticeable
amount of argillaceous deposit with the quartz-grains, it is now
often seen to consist largely of the same mixture of new white mica
and chloritic matter; and in this way we pass back again towards
altered sandy shales, as the interstitial constituents increase.
It is noticeable, however, that whereas among the altered shales
it is but seldom that brown mica is seen as a contact-mineral, and
then only to a very subordinate degree, we find it more frequently
and much more plentifully among the argillaceous sandstones. In
one case from Rumbling Churn, near Dunstanburgh, there is as
large a development of this biotite as might occur at any granite-
contact, and all the characteristics of the mineral are the same.
In previous allusions to the contact rocks of the Whin Sill
(Guou. Maa., April, 1895) I had occasion to refer to the interesting
question of the supposed transfer of soda from the igneous rock to
the altered shales, etc., in such cases of basic intrusions. I pointed
out that observers of the contact-effects of such rocks elsewhere had
been forced to come to the conclusion that such a transfer does often
take place, a very considerable mass of chemical and other evidence
rendering any other verdict difficult, or even impossible. Most of
our knowledge on this point comes to us from German petrologists,
though instances of altered rocks rich in soda are not lacking in this
country.
When I commenced working at the petrology of the Whin Sill
contact I naturally gave attention to this very important point,
and it so happened that some of my first analyses, and separate
determinations of alkalies in altered shales, very strongly confirmed
the views expressed by the German authorities. In the course of
the work I have made a considerable number of further determina-
tions, the general result being that the answer obtained is not at all
uniform in its direction. There are many of the shales in which soda
DECADE IV.—VOL. V.—NO. II. 6
82 Notices of Memoirs—Dr. G.F. Matthew—Cambrian Genera.
has increased very considerably ; but there are also plenty of others
in which this is not the case, even with highly altered rocks close to
the contact, the normal excess of potash over soda having remained
undisturbed ; and the evidence, as will be seen, is rendered all the
more contradictory by the fact that in a given vertical section of
beds we may have a rock quite near the Whin, showing this
chemically unchanged condition, whilst another one, further away
from contact, shows a great increase of soda relatively to the potash.
As previously pointed out, the rocks along the Whin Sill are not
specially favourable for the study of the chemical aspect of the
metamorphism, inasmuch as the igneous mass is intruded parallel
to their strike, and we cannot take any one bed at a distance and
follow it gradually up to the contact. All we are able to do is to
rely on the fact that, apparently without any exception, the normal
shales of the Carboniferous show an excess of potash over soda
within certain limits. All the trustworthy chemical evidence
available shows this to be the case, and I have myself confirmed
it by large numbers of careful determinations, published and
unpublished, on specimens from various localities; the two latest
being a fireclay and a shale which I took from the neighbourhood
of Bardon Mill, near to the exposure of the Whin Sill and its
contact-rocks, but quite outside the area of its metamorphic action.
The alkalies contained are respectively :—
Potash... 900 500 2°62 per cent. and 2°66 per cent.
Soda mt se 500 0:98 st and 1°24 a
The three analyses given above of calcareous adinoles are all striking
instances of a large increase in soda. The total, alkali-contents are
all three high, though not higher than may be seen in some cases of
chemically normal shales. But soda far exceeds potash in all of
them. No shales of similar composition exist outside the contact-
zone, and however we may explain the transfer of soda, we cannot
very well deny its occurrence. This increase of soda, as a chemical
fact, is accompanied by the mineralogical fact of the appearance
_ of albite in the altered rock. Had we these cases only before us,
there would not seem to be much difficulty in accepting the
statements of previous observers on the subject.
(Lo be continued.)
INKS) ARIK OIHS, Oa IME sens SS).
J.—Some CHaAracTEristic GENERA OF THE CAmpBrian.’ By G. F.
Marrnew, LL.D., D.Sc., F.R.S.C.
HE paper gives in brief the history and use of several generic -
names, and the distribution of certain species to which they
have been applied. These genera have an important bearing on the
antiquity of the Olenellus Fauna. Bathyuriscus, Meek, known as
a Middle Cambrian genus in Montana and Nevada, occurs in the ©
Olenellus Fauna of Kastern North America. It is nearly allied
1 Paper read in Section C (Geology), British Association, Toronto, August, 1897.
Notices of Memoirs— Dr, Ells—Problems in Quebec Geology. 83
to the following genus—Dolichometopus, Angelin, of the Upper
Paradowides Beds of Sweden, and is found in beds of similar age in
Hastern Canada. With it is associated Dorypyge, Dames (= Olenoides
in part of Walcott), which is a Middle Cambrian genus in Montana
and is found also in the Olenellus Fauna of Eastern North America.
Microdiscus, a genus of small trilobites, extending in Hastern Canada
up to the Upper Paradoaides Beds, is found in the Olenellus Fauna.
Agnostus has a peculiar development in the Upper Paradowides Beds
in the appearance at that horizon of the section Levigati; the
Brevifrontes also abound there. These two sections appear to be
present in the fauna with Olenellus.
If we accept the view that there has been a regular development
of the faunas through Cambrian time, it is difficult to understand
how Olenellus can be at the base of the Cambrian succession and yet
found in company with so many genera and subgenera which are
known members of the Middle Cambrian fauna, or that of the Upper
Paradoxides Beds. Olenellus has not yet been found below the
Paradoxides Beds, and the evidence adduced indicates that it ex-
tended above rather than below this part of the Cambrian system.
Ii.—Prositems in Quesec Grotocy.’ By R. W. Ents, LL.D.,
F.R.S.C., of the Geographical Survey of Canada.
fY\HIS paper is a brief review of the geological work done in the
province of Quebec since the appearance of Dr. Bigsby’s first
paper on the geology of the province in 1827. It contains a short
statement of the conclusions arrived at from time to time by the
various workers in this field regarding the structure of the rock
formations east of the St. Lawrence, as well as of the Laurentian
complex to the north of that river. A summary of the latest views
reached from the detailed study of these areas during the last fifteen
years, which has appeared in the last volume of the Geological
Survey’s Report, is also presented.
In regard to the structure of the older crystallines north of the
St. Lawrence and Ottawa rivers, it may be said that the opinion
once held, that these rocks were originally of sedimentary origin,
has now been greatly modified. The Laurentian rocks of Logan
are now divided into two great groups. Of these, the lower is
essentially a gneiss formation, and may be styled, for the sake of
distinction, the Fundamental Gneiss. This is clearly older in point
of time than the series of crystalline limestones, quartzose grey
gneisses, and quartzite with which they are often so intimately
associated as to render the determination of their true relations in
the field difficult, but which at other points are clearly situated
above the lower gneiss formation.
These newer gneisses and limestones, which have been styled by
Logan the “‘ Grenville Series,” are, without doubt, for the most part
of sedimentary origin, though they are invaded in all directions by
masses of granite, greenstone, and other forms of igneous rock. As
for the Fundamental Gneiss, also once supposed to be largely of
? Abstract of paper read in Section C (Geology), British Association, Toronto, 1897.
84 Notices of Memoirs—Dr. Elis—Problems in Quebec Geology.
sedimentary origin, it has been very conclusively demonstrated,
chiefly through the agency of the microscope, that this is for the
most part at least an altered igneous rock, and that the supposed
bedding planes owe their existence to other causes than those of
sedimentation.
The original Upper Laurentian division, which included the great
area of the Anorthosite rocks, also supposed at one time to represent
altered sedimentary deposits, has been removed from the position it
once occupied, since it has been proved, both by the evidence in the
field and in the laboratory, to be of igneous origin and subsequent: to
the deposition of the limestone and quartzite series with which it is
associated, so that the Grenville Series, according to the earlier
view as to the succession of strata, may now be taken to represent
the upper portion of the Laurentian system.
It may also be assumed to represent the lowest division of the
clastic or sedimentary rocks in Canada. The relations of these
to the rocks which have been styled the “Hastings Series” in
Ontario are such that they may, in part at least, be regarded as
portions of the same series which have been described in different
portions of the field under different names; but whether these be
regarded as belonging to the Laurentian or Huronian systems, is
of small moment so long as their true relationship to each other
and to the underlying Fundamental Gneiss is clearly understood.
To the east of the St. Lawrence the old dispute as to the age
of the fossiliferous rocks near the city of Quebec, as well as of their
relations to the crystalline schists of the mountain area in the
interior of the province, may now be considered as satisfactorily
settled. The former hypothesis by which the crystalline schists
were regarded as the equivalents, in point of time, of the
fossiliferous sediments of the St. Lawrence Valley has been clearly
shown to be unfounded, and the schists of the Sutton Mountain
area are now assigned to the Huronian system, or are at least
beneath the lowest Cambrian of the district. The relative position
of the several divisions of the fossiliferous Quebec group has also
been ascertained, and it is now established that the Sillery division
is situated stratigraphically beneath the Levis, instead of being,
as was at one time supposed, above it. As regards the age of
the several divisions of the Quebec group (fossiliferous), it may
be said that the Lévis is the apparent equivalent of the Calciferous
formation, and that in its upper portion it approaches the Chazy ;
while the upper portion of the Sillery is the apparent equivalent
of the Potsdam Sandstone formation. Between the upper Sillery
and the great mass of the rocks which have been referred to this
division, there is a fault of considerable magnitude, so that the ~
lower portion of the Sillery presumably includes rocks which have
been elsewhere classed as Cambrian, and these may extend as low as
the Paradowxides zone or division of that system.
The areas of black slate and limestone, which, in the General —
Report for 1863, were regarded as beneath the crystalline schists
and referable to the Potsdam formation, have been determined, on
Reviews— Geological Survey of Scotland—Geology of Cowal. 895
the evidence of the contained fossils, to be much newer, and to
be in fact the equivalents of the lower portion of the Trenton
formation ; and to this horizon may also now be assigned the greater
portion of the strata in the city of Quebec. Here, however, there
are a number of anticlinal folds, and the presence of certain fossils,
similar to those obtained from the Lévis beds, indicates that along
some of these folds beds of that horizon may be found. The same
age may be assigned to the great extension of the black slates
and limestones which occur at intervals along the south shore of
the St. Lawrence, nearly to the extremity of the Gaspé Peninsula,
and which appear to dip beneath the strata of the Sillery formation
at many points. 3
In regard to the use of the term Potsdam a distinction must now
be made between the Potsdam formation and the Potsdam Sand-
stone. The latter has been clearly proved in Canada to be the lower
portion of the Calciferous formation, and is not separable from it,
while there is a manifest break between this and the lower beds, or
the Cambrian proper. The term Potsdam formation in Canadian
geology was a comprehensive one like the term Cambrian, and
like it included all between the Calciferous formation and the
Huronian. The discriminate use of the terms has led to much
confusion, and as the divisions of the Cambrian have now been
properly determined the expression Potsdam formation has practi-
cally no meaning in Canadian geology.
35) Jen We abana Se
sual Sa.
Memoirs oF THE GrotocicaL Survey, Scottanp: Tur GEroLocy
or Cowat, including the part of Argyllshire between the
Clyde and Loch Fine. By W. Gunn, F.G.S., C. T. Croues,
M.A., F.G.S., and J. B. Hitz, R.N.; with Petrological Notes
by J. J. H. Teatt, M.A., F.R.S., Sec.G.S., and Dr. Hatcu,
Ph.D., F.G.S. 8vo; pp. 333, with index, numerous illustrations
in the text, and 10 plates. (Edinburgh: Neill & Co. Price 6s.)
ee Director-General of the Geological Survey observes, in his
Preface to this Memoir, that the district known as Cowal
“embraces the south-western extension of the various bands of
metamorphic rocks which form the southern edge of the Highlands.
Bounded on three sides by coast-lines, and penetrated by a number
of sea-lochs, it affords better and more continuous sections of these
rocks than are generally to be met with in the interior of the
country. . . . . From the detailed study of this part of the
Highlands much information has been obtained by the Geological
Survey regarding the structures of the schists and the successive
movements by which these structures have been produced. Originally
most of the rocks described in the following chapters formed a thick
series of sedimentary deposits, the geological age of which still
remains to be determined. These strata have been found to have
undergone a remarkable series of repeated movements. After being
thrown into folds and having been cleaved so as to acquire a first
86 Reviews— Geological Survey of Scotland—
system of deformation, they have again suffered a repetition of the
process more than once. They consequently represent secondary
and tertiary, perhaps even quaternary, structures, probably due to
mechanical movements with accompanying recrystallization. The
regional metamorphism thus produced is not uniformly distributed,
but seems to increase in intensity both from the south-east and
north-west towards a nearly central line, ranging about north-east —
and south-west, which is an anticline of the foliation. It has not
been traced to any intrusion of igneous rock, and is so general and
diffused that it can hardly be regarded as in any sense a contact
phenomenon. Where intrusive masses occur in the district they
have given rise to their own accompanying alteration, quite apart
from the general metamorphism of the whole area. These in-
teresting and complicated structures, so well displayed in Cowal,
are fully discussed in the present Memoir.”
The Director-General further observes that “ Mr. Clough, having
mapped by far the largest part of the whole district, has had general
charge of the Memoir, which is mainly written by him.”
The extreme length of the district in question, from Ardlamont
Point on the south-west to the granite edge in a north-easterly
direction, is about 44 miles; with a breadth of about 18 miles from
Toward Point on the Firth of Clyde to Otter Beacon on Loch Fine.
The country is mountainous, though the elevations nowhere quite |
attain 8,000 feet, and may be said to decrease rather uniformly towards
tke south-west. By far the larger portion of the area is occupied by
metamorphic rocks. Subjoined is a list of these, not to be regarded
as representing a stratigraphical sequence.
ScCHISTS PROBABLY OF SEDIMENTARY ORIGIN : —
Phylhtes, including the two series of Dunoon and Ardrishaig, which consist
of phyllites and thin limestones, mixed in the first series with schistose
grits and in the second with quartzite schists.
Schistose grits and greywackes.
Quartzite schist or quartz schist.
Albite schist.
Garnetiferous mica schist.
Graphite schist.
Schistose limestones on various 1s horizons, including the Loch Tay limestone.
Mica schist. Areas coloured thus in the maps may also include unseparated
albite schists, sheared grits and greywackes, and phyllites.
Green beds: chlorite- epidote schists. The group lines may include some
mica schists and schistose greywackes.
Tenzous Rocks :—
Epidiorites, hornblende and chlorite schists, serpentine.
Besides the above a number of unfoliated igneous rocks occur
intrusive in the schists.
The age of the schists, even in relation to each other, is not
certainly known, but the different bands are seen to traverse the region
in a north-east and south-west direction. The intimate structure
of the rocks is described with much detail. Amongst the physical
features of the more quartzose beds may be noted the occurrence of -
pebbles, mainly of quartz, felspar, or clay-slate. These pebbles have
been subjected to a stretching action, which is supposed to have
The Geology of Cowal. 87
taken place at the time of the production of the streakiness seen on
the foliation planes of the adjoining phyllites, and probably both were
accompaniments of the production of foliation. The elongation seems
comparable to the distortion of fossils on the cleavage planes of slate.
The behaviour of the several groups towards the great central
anticline of foliation presents some very interesting features. ‘ In
‘the anticline’ folds (says Mr. Clough) with axes hading north-
west, it is the under limbs of anticlines that have a tendency to be
most thinned, whether we are on the south-east or north-west side
of the centre of the anticline. Hence, if we regard the early ‘ pre-
anticline’ folds as having originally had axes hading north-west, the
same law of the greater thinning of under limbs of anticlines prevails
in both; and we may conclude that thé source of the pressure
which produced them both lay to the north-west of the area being
described, and that the pressure was outwards from the Highlands
in a south-east direction. The evidence in the north-west of Scot-
land is now well known to show that there were there, partly at all
events in Post-Cambrian times, mountain-making forces pressing
outwards from the Highlands in a W.N.W. direction. Hence the
central Highlands represent an area from which earth-moving forces
have pressed outwards, on the one side in a west-north-westerly and
on the other side in a south-easterly direction.”
The bulk of the schists are regarded as probably of sedimentary
origin. Chapters iii and iv are devoted to a detailed description
of them. The albite schists present some curious features. They
occur mainly towards the anticline centre, and at Lochgoilhead all
the more micaceous schists contain albites. The albite spots are
almost confined to the micaceous and chloritic beds, and it is doubtful
whether they occur at all in the more quartzose pebbly beds. It is
inferred from their never showing any appearance of stretching that
the albites are of later age than the mass of the movements affecting
the rocks in which they occur.
The “Green Beds” present another curious group of rocks.
These are of a mixed and variable character; for on the north-
west side of the anticline about one-half of the group consists of
other schists, whilst on the south-east side the different outcrops
are comparatively unmixed. They are described for the most part
as epidote-chlorite schists, and are often intersected by thin quartzose
veins coloured green by epidote [? the ‘“‘epidosite”’ of Sterry Hunt].
Of the schistose igneous rocks, the epidiorites, hornblende schists,
and related chlorite schists, associated with the presumed sedimentary
series, are most abundant towards the side of Loch Fine. They are
generally harder than the schists, and thus help in working out
the physical structure. It is believed that they represent old
intrusions rather than lava-flows. There is a special danger of con-
fusing some of these old igneous rocks with the ‘“ green beds.” In
the area between Stralachlan and Loch Fine, these epidiorites, etc.,
form huge irregular masses behaving on a large scale like sills with
irregular protrusions, the longer axes of which coincide with the
strike of the main mass, and of the quartzites in which they are
88 Reviews— Geological Survey of Scotland—
intruded. Mr. Teall gives the following description of their ap-
pearance under the microscope: ‘ Uralitic hornblende, a saussuritic
aggregate of water-clear felspar and granular epidote, irregular
patches of sphene (leucoxene) and aggregates of chlorite.”
In chapter vii the minerals of the schists are enumerated and
partly described, whilst much attention is paid to the direction of
stretching. Chapter viii is devoted to the general physical structure
of the schists, together with remarks on metamorphism. The most
conspicuous feature of the schist area, as may be inferred from
previous remarks, is the great anticline of foliation running in
a direction about 35° W. of S. through the heads of Loch Goil, Loch
Striven, and Loch Riddon, and the hills about a mile north-west of
Tighnabruaich. There is no doubt that this anticline is a true arch
of an early foliation; but scarcely perhaps an anticline of bedding.
The authors (and more especially Mr. Clough) apparently conclude,
after much weighing of the evidence, that at least five of the groups
on the north-west side of the anticline are unrepresented on the south-
east side, notwithstanding some apparent points of resemblance.
Lines of actual rupture contemporaneous with the schist-making,
comparable to the “thrusts” of the north-west of Scotland, probably
do not occur anywhere in Cowal, except on the smallest scale, such
as strain-slips with throws not exceeding a few inches. The
numerous faults which have been mapped and which have effective .
throws, are all later than the schist-making, and break up the
minerals and planes of schistosity instead of helping to form them.
To the question regarding the agents which produced the general
metamorphism of the district, Mr. Clough considers that it would
be premature to reply; but he does not consider that there is any
exposure of igneous rock which would account for it. The alteration
effected by the Glen Fine granite, for instance, does not extend for
more than a mile, and is of quite a different character.
The direction of the boundary fault between the Schists and the
Old Red Sandstone is nearly parallel to that of the centre of the
anticline. This fault cuts off a shred of Upper Old Red Sandstone
rocks, which thus appear at the extremity of the peninsula that
terminates in Toward Point. They consist, in the main, of red
breccias and sandstones mixed with occasional blood-red and
variegated shales; calcareous sandstones and magnesian limestones
are numerous on a certain horizon. One of the sections which best
illustrates the relations between the red marls and the metamorphic
schists occurs on the shore just to the south of Inellan pier.
Chapters x to xiv are devoted to the igneous rocks (unfoliated).
A small part of the igneous complex of Garabhal Hill, ete., comes
within the district. These are, in fact, granitites with a tendency
to pass into a coarse dioritic rock; the granitic rocks are generally
characterized by abundant porphyritic crystais of orthoclase felspar.
Considerable attention is paid to the character of the metamorphism
near the edge of the plutonic rock, chiefly with a view to contrast -
the metamorphism special to its neighbourhood with that further
away near the anticline of Cowal.
The Geology of Cowal. 89
Hornblende-porphyrites and felsites are classed together, since the
Same porphyritic constituents, viz., felspar, black mica or chlorite,
sometimes hornblende, and scattered quartz blebs, occur in both.
These rocks behave in the field in the same way as the lamprophyres
(presently to be mentioned), generally forming sheets which run
roughly with the foliation of the schists; they are of limited extent.
An intrusive boss of some importance is also described as hyperite,
the rock consisting of hypersthene, augite (diallagic in part),
plagioclase (more or less lath-shaped), iron-ores, and interstitial quartz.
Of the older igneous rocks are those described under the terms
lamprophyre and mica-trap. It is only when the mica is
macroscopically prominent that the latter term seems applicable.
By a gradual decrease in the amount of mica the mica-dolerites may
pass into rocks of more normal doleritic aspect. In all these early
dolerites which have been examined the augite differs from that
of the Tertiary basalts in belonging to the pale form, malacolite, and
for the most part occurring porphyritically. In the north and east
of Cowal these lamprophyres are exceedingly numerous, but they
are not known within a distance of four or five miles of the Upper
Old Red Sandstone boundary. They rarely form vertical dykes;
when they do so, these dykes usually run in a different direction _
to that of the basalts. Most frequently they occur as sheets with
varying and not very steep hades to the horizon. They do not keep
to the bedding or foliation of the schists, but may be constantly seen
cutting across their crumplings. It is evident that all the move-
ments in connection with the foliation of the schist had ceased before
their intrusion. Though thin and inconstant, the lamprophyres are
of considerable interest in working out the geological structure of
the district, and a greater help than the basalts. This is because the
majority of the faults are of later date than the lamprophyres, and
throw them, so that they help to indicate the different faults and even
the amount of their respective throws, independently of the schists.
An inspection of the geological map will show that parts of Cowal
are seamed by basaltic dykes: this subject is very fully treated in
the Memoir. Basalts, dolerites, and tachylites constitute the group,
with which even augite-andesites are included. Thin margins or
selvages of distinctly glassy rock, tachylite, are common, but not to
be found without close search. One of the most curious features of
basaltic dykes, especially noticeable on the coast, is the tendency for
some to weather in relief, whilst others form recesses sometimes
hollowed out into caves. The authors consider that the size of the
grain is often a determining factor in these cases. The intimate
structure of the basaltic rocks is treated of at considerable length.
With respect to the relative age of the dykes, the broad east-and-
west dykes are regarded as older than the basalts having a north-
west direction. ‘If we suppose the early east-and-west dykes
to be of Carboniferous age, the interval of time between them and
the north-west dykes must be immense; for there can be no doubt
that many of the latter belong to the same set as those which, still
with a north-west direction, are seen in the island of Mull to intersect
90 Reviews— Geological Survey of Scotland—Geology of Cowal.
the bedded basalts of Tertiary age.” The very conspicuous east-and-
west dykes at Ardlamont Point are not crossed by any running north
and south; but, since these are regarded as continuations of the two
large dykes crossing the island of Bute, where one of them is
clearly cut by later Tertiary dykes, we may infer that the Ardlamont
dykes are of earlier date than the Tertiary period. Similar con-
clusions result from the detailed examination of other districts.
Within this area only five intrusions have been recognized as trachyte:
these are all dykes, which are considered to be later than the basalts.
Three chapters are devoted to the general geological structure of
particular districts, and the numerous sections given in the text are
of great service to the readers in this connection. The structure
of the country about Lochgoilhead, for instance, is particularly
interesting on account of its proximity to the anticline. Moreover,
since the much frequented coach-road through Hell’s Glen traverses
this region, it enjoys the advantage of being easily accessible.
Two chapters, illustrated by a special map (Clough), are devoted to
Glacial deposits. The following features are indicated in the map :—
(1) Landslips; (2) marine and fresh-water alluvia and peat in basin-
shaped hollows; (8) boulder-clay and sandy drift without definite
moraine shapes; (4) drift with well-defined moraines. The
direction of the striz ranges from §.W. through §. to 8.E., with
few exceptions.
The remaining chapters deal with such subjects as marine and
fresh-water allan. peat, landslips, blown sand, prehistoric¢ HOUT
geological aspects of the scenery, and economic resources.
In the appendix Mr. Teall makes some general remarks on ihe
petrography of the district. After insisting on the well-known fact
that, in a complex series of stratified deposits, the coarser-grained
sediments retain traces of their original character long after all such
traces have disappeared from the finer-grained deposits, he proceeds
to illustrate the point with reference to the gneissose grits (the
schistose grits and greywackes of the Memoir) so largely developed
in the Southern Highlands. Although distinctly gneissose in
structure and composition, they differ markedly from igneous
_ gneisses in their relation to the other rocks with which they are
associated, and frequently contain relics of original grains of quartz,
often bluish in colour, and felspar. The rocks of this class are
crystalline schists essentially composed of quartz, felspar, and one
or two micas: they are therefore gneisses in the usual sense of the
term. Where conspicuous traces of their clastic origin remain they
may be termed gneissose grits; when all, or nearly all, such traces
have disappeared they may be termed granulitic gneisses: they pass
by insensible gradations into felspathic mica schists. ;
Plates i to v are reproductions of photographs of Natural Rock —
Exposures, taken by Mr. R. Lunn. The Geological Survey of Scotland
is to be congratulated on these most effective pictures of contortion,
which are at once instructive and picturesque. ‘The other plates are _
likewise very good of their kind, and the volume generally may be
deemed a most satisfactory contribution to geological literature.
Reports and Proceedings—Geological Society of London. 91
seven @iev ae Se AlN») eer @ Cr ban GS
GroLoaicaL Society oF Lonpon.
I.—December 15, 1897.—Dr. Henry Hicks, F.R.S., President,
in the Chair. The following communications were read :—
1. “On the Pyromerides of Boulay Bay, Jersey.” By John
Parkinson, Hsq., ¥.G.S.
After briefly noticing the literature of the subject, the author
describes the altered rhyolites of Boulay Bay. One variety, the
commonest, is of a dark-red colour, showing flow-structure ; another
is porphyritic; a third, near the centre ‘of the Bay, has a pale-
greenish matrix enclosing fragments, which, however, are due to
flow-brecciation. Large “pyromerides occur in two localities; in
the more interesting, ‘that north of the jetty, the structure of the
rock indicates either a very peculiar magmatic differentiation in siti
or (more probably) the mixture of two magmas differing in their
stage of consolidation.
From study of a series of specimens of the pyromeridal rock, the
author arrives at the following conclusions :—(1) The rock shows
marked flow-structure and at times bands which indicate a slight
difference in its composition, the latter tending to assume a monili-
form outline. In such the microscopic structure corresponds with
that of the pyromerides, and exhibits traces of radial crystallization.
(2) These afford a passage into somewhat oval pyromerides,
with rather tapering ends and irregularly mammillated surfaces.
(3) From these sometimes a single one seems to be thrown off,
while lines of pyromerides or little lumps of similar material are
scattered about the matrix. (4) Many of the pyromerides are solid
throughout ; others have a central cavity filled with quartz.
The author describes varieties of the pyromerides. They are
generally deep-red in colour, and exhibit (a) fluxion-structure, made
more distinct by minute black microliths; (b) a radial structure ;
(c) a “patchy” devitrified structure (with crossed nicols) ;—the
second (b) being not always present. The matrix is usually of
a greenish tint, showing devitrification-structure and sometimes a
trace of perlitic structure.
The pyromerides frequently exhibit more or less crescentic cracks,
due apparently to contraction, which have been filled by quartz.
Sometimes also they scale off in rudely crescentic shells. In one
locality a variety with good spherulites, about as large as a pea,
passes into one showing a fluxion-structure and pyromerides, having
traces of radial structure as well as clots and irregular ‘ wisps,”
suggestive of a stiffer material broken up by one more liquid.
‘As the result of his studies, the author thinks that while very
regular spherulites do occur, apparently in consequence of radial
erystallization round a centre, the pyromerides are due to the mixture
of two magmas slightly different in composition and fluidity, the less
plastic of the two being sometimes drawn out into streaks, but at
others forming lumps, in which, where their form is suitable, a radial
92 Reports and Proceedings—Geological Society of London.
structure is subsequently developed. He concludes by comparing
the pyromerides of Boulay Bay with specimens from other localities
described by MM. Delesse and Lévy, Professor Iddings, and Miss
Raisin, or collected by himself, and by discussing the quartz-filled
cavities which occur in certain cases. ‘These he regards as originally
vesicles, and not due to any subsequent decomposition.
2. “On the Exploration of Ty Newydd Cave near Tremeirchion, ~
North Wales.” By the Rev. G. C. H. Pollen, 8.J., F.G.S.
In November, 1896, a Committee was formed, consisting of
Dr. H. Hicks, Dr. H. Woodward, and the author, for the purpose of
exploring this cavern, which is situated in the same ravine on the east
side of the Vale of Clwyd as the well-known caverns of Ffynnon
Beuno and Cae Gwyn, explored about twelve years ago by Dr. H.
Hicks and Mr. H. B. Luxmoore. Grants have been made by the Royal
Society and by the Government Grant Committee for the purpose of
carrying on the explorations ; and though a considerable time must
elapse before the work is completed, the results already obtained are
of so much importance that the author has thought it advisable to
bring them before the Society. In the work of exploration he
has throughout been ably assisted by the theological students of
St. Beuno’s College. The cavern had been in part broken into by
quarrying operations, but the chambers and tunnels were completely
filled up with more or less stratified deposits, and had remained
entirely untouched.
Although the ground above the cavern is strewn over with drift
and erratics from the North and from the central areas of Wales,
not a fragment of anything but immediately local material has been
discovered in the cavern itself, showing clearly that the deposits in
the cavern had been carried in by water before the Northern and
Western ice had reached this area. ‘he work has been carried on
almost continuously throughout the year, and most of the material
has been removed for a distance of over 60 feet from the entrance.
The height of the cavern above sea-level is 420 feet, or about 20 feet
above the floor of the Cae Gwyn Cave.
The following points appear to the author to be now fully
established :—
(1) The material in the Ty Newydd Cave, as in the lower parts of
those of Ffynnon Beuno and Cae Gwyn, is of purely local origin.
Of this he can speak with confidence, as the question was betore
him from the beginning, and the gravels were examined with minute
care for erratics.
(2) This local deposit is of earlier date than the Boulder-clay with
Western and Northern Drift. This was proved by the finding of
granite- and felsite-boulders abundantly at higher levels and over
the cave, and in one case filling the upper part of one of the fissures
communicating from above with the cavern.
(3) The occurrence of the tooth of a large mammal (Rhinoceros) _
in the lower part of the cave shows that the animal was con-
temporary with, or of earlier date than, the infilling of the cavern
by the local dritt.
Reports and Proceedings—Geological Society of London. 93
IJ.—January 5, 1898.—Dr. Henry Hicks, F.R.S., President, in the
Chair.
Professor Judd drew attention to the outline geological maps of
England and Wales on the scale of 80 miles to the inch, for the use
of schools and colleges, presented by John Lloyd, Esq. These were
reproduced, by permission of the Science and Art Department, from
the maps in use at the Royal College of Science, South Kensington.
The following communications were read :—
1. “On the Structure of the Davos Valley.” By A. Vaughan
Jennings, Hsq., F.L.S., F.G.S.
Hvidence is brought forward to show that the level area, about
four miles in length, near Davos is occupied by superficial deposits,
and that the lateral talus-fans there have been cut through at
a relatively recent date since their accumulation ; that the northern
end towards Wolfgang is blocked by moraine-material of great
thickness, but for which the Davoser See would drain north to the
Landquart, carrying with it the waters of the Fluela and Dischma ;
that the contour-lines suggest the former existence of a far larger
lake stretching south towards Frauenkirch, and that in that part
there is proof of the previous existence of a great detrital fan
sufficient to account for the existence of the lake in question.
It is shown that the former ice-movement was not from the
present watershed between the tributaries of the Landwasser and
Landquart, but from a spot farther south.
The author concludes that the main valley-systems were marked
out in Pre-Glacial times, and that at one time there was a water-
shed somewhere between Davos Platz and Frauenkirch. During
the Glacial Period moraine-material was heaped up across the valley
below the Hornli, and held up the waters to the south, forming
a great lake of which the present Davoser See is a relic, the outflow
being probably over a low saddle near the present Wolfgang ;
during this time a great moraine and detrital fan existed across the
valley to the south, and the lake for a long time was thus prevented
from draining in that direction. After the Glacial Period the
northern moraine was subjected to little erosion, but the southern
one, formed from the first of looser material, was rapidly cut back
by the Sertig Bach, and in time the barrier was so weakened as to
cause that end of the lake to be tapped, and at that time the terraces
opposite Frauenkirch may have been levelled, while the flow over
Wolfgang would be stopped, and the Fluela and Dischma streams
turned southward ; the Landquart would then cut away the margins
of the talus-fans which had been accumulating in the lake.
2. “Sections along the Lancashire, Derbyshire, and Hast Coast
Railway between Lincoln and Chesterfield.” By C. Fox-Strangways,
Hsq., F.G.S. (Communicated by permission of the Director-General
of H.M. Geological Survey.)
The portion of the line considered in this paper occupies a distance
of about forty miles, and runs nearly at right angles to the strike of
all the beds from the Lias to the Coal-measures.
94 | Obituary—G. H. Piper, F.G.S.
The lower part of the Lias and the Rhetic beds are entirely con-
cealed; but grey marls overlying red marls occur about half a mile
east of Clifton Station, and at the station the Red Marl of the Keuper
comes on in force. The alluvial deposits of the Trent, pierced to
a depth of from 25 to 30 feet, consist principally of loam overlying
varying thicknesses of sand and gravel. Horns of red deer were
found at a depth of 25 feet. At Dukeries Station white flaggy
Keuper sandstones appear from beneath the Red Marl, and probably
represent the eastward extension of the Tuxford Stone. A deep well
here has been bored to a depth of 644 feet from the present surface,
and details of the section are given in the paper. South of Kirton
there is a deep cutting in the Waterstones, and after leaving the
escarpment the line enters on the great dip-slope of the Bunter
Pebble Beds, which are shown at Ollerton and at intervals for four
miles beyond this. There are no sections in the Lower Red and
Mottled Sandstones ; and west of Warsop the line crosses the dip-
slope of the Magnesian Limestone. Details of the sections in this
rock are given.
Between Scarcliff and Bolsover the line crosses the Permian
escarpment in a tunnel, the whole of which is in the Coal-measures ;
these are high up in the series, and contain no coal-seams of value.
They are not stained red.
West of Arkwright’s Town Station is a very complete section of -
beds representing the Middle Coal and Ironstone series (the most
valuable part of the Derbyshire Coalfield), of which full details are
given, most of the important coal-seams being readily recognized ;
and the author describes some remarkable features in the relation-
ships of some of the sandstones to the other deposits.
The absence of Glacial beds is of much interest; not a trace of
genuine Boulder-clay has been seen along the whole line.
(Qs SALA Ol INAS INS.
GEORGES HARRY JER ERE sEaGrss
Born Aprit 8, 1819. Dizp Aveust 26, 1897.
Tur subject of this brief notice, the second son of the late
Captain EH. J. Piper, R.N., was born in London in 1819, in the
neighbourhood of Regent’s Park, where his family resided. His
parents removed to Herefordshire in 1829, taking their son George,
then a boy of ten years old, with them. Naturally an observant
youth, country life and pursuits, after London, had a great
attraction for him, and he speedily became interested in studying —
the birds, trees, and flowers, and early learned to fish and shoot.
When only fourteen, however, his health gave way, and he had to
remain in bed for about three years, suffering from a lame leg, and
was never entirely free from pain during the remainder of his life. -
As a consequence of this, his education was carried on at home,
in a more or less desultory manner. Nevertheless, he was a keen
Obituary—G. H. Piper, F.G.S. 95
scholar, and at about eighteen years of age he was duly articled to
the late Mr. Thomas Jones, Attorney of Ledbury ; and having served
his master and duly passed his examinations in law, he was
admitted as a Solicitor in 1849, and from that time commenced
to practise in Ledbury, where he continued in his profession until
his death. He was joined in partnership by Mr. C. HE. Lilley in
1886, and was one of the oldest solicitors in the county. In
addition to his private practice he also held appointments as
Commissioner to Administer Oaths, Perpetual Commissioner, etc.,
Deputy-Registrar, and in 1865 Registrar, of the County Court
and High Bailiff of the Court, which offices he held up to the
time of his death. .
Mr. Piper took a keen interest in the progress and work of
the Horticultural and Natural History Societies of the County of
Hereford, and had filled the position of President both of the
Woolhope Naturalists’ Field Club and the Malvern Naturalists’
Field Club. To these Societies he communicated many papers, and
with them he did much excellent work in botany, local archeology,
and geology, more especially in the latter field of research.
Mr. Piper’s geological work was carried on for years in
association with the late Rev. W. S. Symonds, M.A., F.G.S., of
Pendock Rectory, Tewkesbury; Dr. Bull of Hereford; the Rev.
P. B. Brodie, M.A., F.G.S., and other enthusiastic workers.
The greatest geological achievement performed by Mr. Piper was
the carrying out successfully, after many years of patient explora-
tion, the complete examination and recording, foot by foot, of the
famous section near the railway tunnel at Ledbury, comprising the
series of deposits from the Aymestry Limestone, through the Upper
_ Ludlow rocks ; the Downton Sandstone, with Péerygotus ; the Ledbury
shales, consisting of red, grey, purple shales, and grey marl-beds,
with Pteraspis, Auchenaspis, Cephalaspis, Onchus, Pterygotus, Lingula
cornea, etc. ; followed by Lower Old Red Sandstone, with Pterygotus,
Pieraspis, and Cephalaspis, ete.
In Mr. Symonds’ paper ‘“‘On the Old Red of Herefordshire”
he writes of the Passage-Beds at Ledbury: ‘“‘ Having again visited
Ludlow, and compared the Passage-beds of that district with those
of Ledbury, I am convinced that nowhere perhaps in the world is
there such an exhibition of Passage-beds presented to the eye of
the geologist as at the Ledbury Tunnel on the Worcester and
Hereford Railway.” See H. Woodward’s “Brit. Foss. Crustacea”
(Merostomata) : Pal. Soe., part ili, 1871, p. 99.
The rich collection of fossils which Mr. Piper formed from the
Ledbury Tunnel Section, and from other localities in the neighbour-
hood, will, it is believed, shortly find a home in the British Museum
(Natural History), Cromwell Road, where so many of his fine
Cephalaspidian fishes have already been presented in past years,
including the superb group of twelve individuals of Cephalaspis
Murchisoni, preserved in one block of Old Red Sandstone— forming
Plate x in Mr. Arthur Smith Woodward’s Catalogue of Fossil Fishes
in the British Museum (Natural History), Part ii, 1891, p. 189—
96 Miscellaneous—Bibliographies.
from the Passage-beds, Ledbury, presented by Mr. George H. Piper
in 1889.
Mr. Piper was elected a Fellow of the Geological Society of
London in 1874, but his numerous scientific papers will mostly
be found in the Transactions of the Woolhope Club.
He was for many years local Hon. Secretary of the Royal Agri-
cultural Benevolent Institution, and took a deep interest in all matters
relating to agriculture, and especially the cultivation of fruit and —
of roses.
He largely assisted in the publication of ‘The Herefordshire
Pomona,” and was with the late Dr. Bull selected to visit Normandy
to inquire into the subject of fruit-culture there and to exhibit
Herefordshire fruit. These gentlemen returned with several prizes
awarded at the Rouen Exhibition for fruit grown in their own
county.
It would be impossible here to convey a just idea of the large and
varied fields of scientific activity and social benevolence to which
Mr. George Piper devoted his long and useful life; but the testimony
of respect shown for him by his fellow-townsmen of all classes at
his funeral might be cited as good evidence that he had not lived
in vain. He was not only highly accomplished in many literary
and scientific fields of inquiry, but ‘‘he was known to all as a genial,
upright, and courteous gentleman, whose life was not spent for
himself alone, but most largely for the good of others. In him the
inhabitants of Ledbury and its neighbourhood have lost an able
lawyer and a much respected friend.” (From Mr. F. Russell’s speech
in Ledbury County Court.)
IMEI S\SsIa IIL /AIN EHO OS
———
A BreriocGraPHuy oF NorroLk GLACIOLOGY, INCLUDING THE CROMER
CLirrs, WITH THE Forest-BED SEeRrES. By W. Jerome Harrison,
F.GS. (Reprinted from the Glacialists’ Magazine for March, June,
and September, 1897.)—This work of 91 pages contains all the titles
and brief abstracts of most of the papers dealing with the Cromer
Forest-bed and the Glacial Drifts of Norfolk, published between
1745 and 1897. To workers on Hast-Anglian geology this will
henceforth be an indispensable work of reference, and all will feel
greatly indebted to Mr. Harrison for the labour and care bestowed
on the work. Two years ago he prepared a similar work on Midland
Glaciology.
A Brptiocrapuy relating to the Geology, Paleontology, and
Mineral Resources of California, has been compiled by Captain —
Anthony W. Vogdes (California State Mining Bureau, Bulletin
No. 10). This is arranged, not chronologically, but according to
the several sources of publication ; there are some explanatory notes —
and there is a good index. The list includes works published up
to 1896.
THE
GHOLOGICAL MAGAZINE.
NEW. SERIES. DECADE IVa »VOLW Vi
No. III.—MARCH, 1898.
ORTGINADL ARTICLIENS.
7.—Tue Farumst Hnaravep GeroLtocicAa, Mars or ENGLAND
AND WALES.
By Professor J. W. Jupp, C.B., LL.D., F.R.S., V.P.G.S., etc.
N a previous article,’ a sketch has been given of what is known
concerning the origin and history of the early manuscript maps
of William Smith. I have shown that concerning these maps,
though they were not published, in the technical sense of that term,
there exists a satisfactory body of external evidence with regard to
the period of their preparation, while they furnish in themselves
abundant proofs that they must have been constructed at the dates
inscribed upon them. These facts have been so generally recognized
that—since the clear statements on the question which have been made
by Fitton, Farey, Sedgwick, and Phillips—no one has ever thought
of either questioning the antiquity of the maps or denying to
William Smith the honour of being the first to construct a true
geological map of England and Wales.
But I find that, even with regard to the later maps and sections
of William Smith, which were actually engraved and published,
there still exists a certain amount of uncertainty. Maps have been
publicly ascribed to Smith, with the preparation of which he
certainly had nothing to do; while, on the other hand, some of the
most important works issued by him have altogether failed to attract
the attention which they deserve.
Immediately after the preparation of the Manuscript Map of
England and Wales in 1801, the question of its publication, on
a larger scale, was seriously taken in hand by Smith and his friends.
A prospectus dated Mitford, near Bath, June Ist, 1801, was prepared
by William Smith, and extensively circulated by Debrett of
Piccadilly (opposite to Burlington House), asking for subscribers
to a work that was to be entitled ‘‘ Accurate Delineations and
Descriptions of the Natural Order of the various Strata that are
found in different parts of England and Wales, with Practical
Observations thereon.” The author promised that this work should
contain “a correct map of the strata, describing the general course
1 GrortocicaL Macazine, n.8., Dec. LY, Vol. IV (1897), p. 489.
od
DECADE IVY.—VOL. V.—NO. III. (
98 Prof, Judd—The Earliest Engraved Geological Maps.
and width of each stratum on the surface, accompanied by a general
section, showing their proportion, dip, and direction; the map and
sections, to make them more striking and just representations of
nature, will be all given in the proper colours.” Smith’s friend
Richardson urged that a Latin edition of the book should be issued
with the English one, and it is certain that if this had been done,
all possibility of contesting Smith’s claim to priority would have
been destroyed.
Unfortunately, however, the failure of the publisher Debrett, and
the limited means and numerous business avocations of William
Smith, prevented the realization of these projects. Thanks, however,
to the splendid loyalty of Smith’s numerous friends—especially
Richardson, Townsend, and Farey—there exists such a body of
evidence concerning Smith’s discoveries and teaching, all published
between the years 1801 and 1815, that no impartial judge can for
one moment hesitate in assigning to Smith that priority so
strenuously claimed for him by Fitton, Farey, Sedgwick, and
Phillips.
Nor can it be justly asserted that the treatment of Smith by his —
contemporaries was other than generous and forbearing. In 1802
prizes of fifty guineas were offered by the Society of Arts for
“mineralogical maps of either England, Scotland, or Ireland, on
a scale of not less than 15 miles to the inch,” and the offer was
renewed year by year down to 1814, when the prize for the English —
Map was claimed by and awarded to William Smith. As Phillips
remarked : ‘ At this moment, any map, however crude and incorrect,
professing to be a mineralogical map of a part of the British Islands,
would have been a source of lasting reputation to its editor; any
account of the principal facts then ascertained near Bath would have
been welcomed with admiration. Had Mr. Smith been exposed to
this ungenerous rivalry, he must have sunk under the grief and
vexation of being anticipated in his map by some inferior com-
pilation, and in his other labours by notices which, in consequence
of his wandering habits and laborious profession, it would have
been more easy for others than himself to have drawn up. But
nothing of this kind happened.”
That a knowledge of William Smith’s ideas and discoveries had
by this time become very widely diffused, not only in this country,
but all over Europe, and even in America, there is abundant evidence.
Manuscript copies of his original table of strata with their fossils had
been widely circulated, and every facility had been given to those
interested in the subject to make transcripts of the maps which were
so freely exhibited by their author. At agricultural meetings of all
kinds Smith was a constant attendant, exhibiting and lending his
maps for inspection; while reports of his explanations of maps and
sections not unfrequently found their way into the newspapers. At
Trim Street in Bath, in the year 1802, and a little later near Charing
Cross, London (Craven Street), a collection of maps and sections, _
with an illustrative series of fossils, was arranged, and exhibited
freely to all who chose to call. This collection of fossils, which
Prof. Judd—The Earliest Engraved Geological Maps. 99
after a fire at Craven Street in 1804 was removed to Buckingham
Street, was purchased by the Trustees of the British Museum in
1816. It originally consisted of 2,657 specimens, belonging to 693
species, collected at 263 different British localities ; and such portions
of it as can be identified have been brought together and arranged
according to William Smith’s original plan in the British Museum
(Natural History) at South Kensington, by the pious care of
Dr. Henry Woodward.
It must indeed be confessed that, between the years 1801 and
1815, not only did William Smith seem to act as though he were
absolutely careless of his claims to priority as a geological investi-
gator, but it is difficult to conceive how he could have adopted plans
more calculated to give rise to controversy as to the validity of
those claims. ,
In 1805 Smith’s large and detailed geological map of Somerset-
shire was completed and publicly exhibited, and a project was started
by Sir John Sinclair, the President of the Board of Agriculture, and
Mr. Crawshay, a warm friend of Smith, to attach the great geological
pioneer to the corps of Engineers then commencing the Ordnance
Survey of the country: had this been done, the establishment of
the English Geological Survey would have been antedated by no less
than thirty years. But this project, as well as attempts made by
Sir Joseph Banks and other friends to procure the publication of
Smith’s map by subscription, were doomed to failure. Smith’s
wandering life, his unfamiliarity with literary work, and his
disinclination to engage in it, no less than the constant attraction
of field-research, by which he was continually making additions
and corrections in his maps, all conspired to render difficult the
publication, in a worthy manner, of the great work which he
had produced.
In 1807 Greenough, with the aid of a few mineralogical friends,
founded the Geological Society. By that date we are told that the
idea of publishing Smith’s geological map was so generally recog-
nized as having been abandoned, that, among the undertakings
recommended to the infant society as especially worthy of its
attention, was that of the compilation of a Geological Map of
England and Wales. The idea was warmly espoused by the
Society, and the work was entrusted to Greenough, by whom the
task was commenced in 1808.
It should always be borne in mind that this work of Greenough,
though of great value in itself, was an undertaking of a totally
different kind from that of William Smith. Smith was a great
original discoverer and creator, and almost every entry on his map
was the result of his own personal observation. Greenough, on the
other hand, was essentially a clever and an industrious compiler.
He received, from the first, valuable assistance from such men as
De la Beche, Buddle, Farey, and other geologists; Aiken contributed
a geological sketch of Shropshire, and Fryer one of the Lake
District ; while Buckland and Conybeare both made valuable con-
tributions to the work. Most important of all was the circumstance
100 Prof. Judd—The Earliest Engraved Geological Maps.
that the actual engraving of his map was entrusted to a geologist
who is second only to William Smith himself in his contributions
to English stratigraphical geology. Thomas Webster, in his letters
to Sir Henry Englefield, published in 1815, had shown that he had
unravelled many of the complexities of the English Tertiary strata,
and laid the foundation of a correct classification of the beds which
underlie the Chalk in the South-East of England; and it was to
Webster that we owe the actual preparation and engraving of the
Greenough Map.
Many years afterwards, Greenough published a Geological Map of
India—a country which he had never visited—by bringing together
all the scattered observations recorded in journals or existing in
manuscript in the Archives of the India House. It would not
be correct to speak of Greenough’s Map of England and Wales
as a mere compilation like his Map of India, for it is evident that
in the case of the former map he took much pains in verifying
and correcting information upon the ground, as is vouched for
by Conybeare and other authorities. On the other hand, Greenough’s
claim that his map should be regarded as an independent work,
when compared with that of William Smith, is one that no geologist
who has studied the question can reasonably allow. In saying
this we do not for one moment impugn the good faith or question the
honesty of Greenough. Owing to the unfortunate procrastination |
of William Smith in the matter of publication, many of his ideas
and discoveries had become public property, even before the com-
mencement of the century, and Greenough may very well have
been quite unaware how much of the current information on the
succession and distribution of the English strata was directly
traceable to the labours of Smith. In 1865, when the Greenough
Map had become the property of the Geological Society, and a third
and revised edition was being prepared, a Committee of the Society,
which included Godwin-Austen, Murchison, Prestwich, and Phillips,
deliberately recommended, as the result of their inquiries, that the
map should henceforth bear the imprint “ based on the original map
of William Smith”; and every unprejudiced student of the history
of geology will agree that the action of the Council in adopting this
suggestion was a wise and just one. Apart from his industry and
perseverance in Cartography, it must be admitted that the claims
of Greenough to be regarded as a pioneer in geological research
cannot for one moment be compared with those of William Smith.
In the same year that his map appeared, Greenough published his
work “A Critical Examination of the First Principles of Geology ” ;
and an inspection of this work will satisfy any geologist that even _
at that date he held the most uncertain views concerning the use and ~
value of fossils, and, indeed, upon all geological principles that were
not included in the creed of the straitest sect of the Wernerians.
In 1812 Greenough laid the first draft of his map before the
Council of the Geological Society, and in the same year William ~
Smith at last found a publisher for his great work in the enterprising
John Cary.
Prof. Judd—The Earliest Engraved Geological Maps. 101
While constructing the small manuscript geological map of England
and Wales, William Smith became convinced, as he tells us, that ‘the
intricacies in the marginal edges” (of the strata) “ were such that
I found to mark point by point, as the facts were ascertained, was
the only way in which I could proceed safely. My experience in
what I had done upon the Somersetshire Map was sufficient to
convince me of this, and that to make a map of the strata on a scale
as large as Cary’s England (five miles to an inch) with sufficient
accuracy, much of it should first be drawn on a larger scale.”
The delay in publishing the work certainly resulted in the Map of
England and Wales being much fuller in detail than it would have
been if issued in 1801. Instead of the eight colours used in the
early map, we find no less than twenty colours employed in the
engraved map of 1815; and three other spaces were introduced into
the legend, though left uncoloured. We also find separate indications
used for collieries, lead-mines, copper-mines, tin-mines, and salt and
alum works, while the distribution of the great areas of granite
and other igneous rocks were fairly indicated. One very important
feature of the map was the inclusion of a section from Snowdon
to the south-east of England, in which the superposition and dip of
the strata and the formation of escarpments and intervening vales
by the agency of denudation are clearly illustrated.
The chief defects in the famous map of William Smith, which
was at last published on August 1st, 1815, were as follows :—The
representation of the Tertiaries was very inadequate, no indication
of the Crags being given, the Isle of Wight Tertiaries, the Bagshot
Beds of Southern England, and the Boulder-clays of Hast Anglia
being all confounded together, and the relations of these to the
London Clay being left obscure. The Wealden area was altogether
unsatisfactorily treated, the argillaceous strata being coloured as
“Oaktree Clay ” and the arenaceous as ironsand (Lower Greensand,
etc.). Lastly, the Jurassic estuarine strata of North Yorkshire were
confounded with the “carstone and ironstone” of the South-Hast of
England. On the other hand, it is interesting to note that Smith
had already learned at this early date the existence of strata lying
between the Old Red Sandstone and the slaty rocks of Wales and
Cumberland. These have a tablet assigned to them in his legend
with the description “various alternations of hardstone, limestone,
and slate,” though the information he possessed was not sufficient to
enable him to extend proper colours for them to the map. This is
probably the earliest notice of the strata afterwards made so famous
_ by the researches of Murchison and his coadjutors.
The period following the issue of his great geological map was
one of much activity to William Smith. In the year which witnessed
the publication of the map (1815) he issued “ A Geological Table of
British Organized Fossils which identify the Courses and Continuity
of the Strata”; and in the following year he prepared the first part
of his “Strata identified by Organized Fossils,” only four parts of
which out of the seven contemplated ever saw the light. In 1817
Smith published an enlarged section from Snowdon to London.
102 Prof. J udd—The Earliest Engraved Geological Maps.
This very important work, which was issued by Cary on July 15,
1817, illustrates in a remarkable manner the clearness of Smith’s
views regarding both the underground structure of the country and
the relations of the forms of the surface produced by denudation to
that structure.
In May, 1819, there appeared seven other geological sections
by William Smith, illustrating the structure of various parts of
England, viz.: (1) From London to Brighton through Lewes ;
(2) through Dorsetshire and Somersetshire to Taunton; (8) through
Hampshire and Wiltshire to Bath; (4) through Norfolk (Yarmouth
to Lynn); (5) through Suffolk to Ely; (6) through Essex and
Hertfordshire; and (7) between London and Cambridge. In all
these sections the relations of the strata with the forms and altitudes
of the hills are well illustrated, the only points open to serious
criticism being the representation of the relations of the London
Clay to the strata above and below it, and the nature and succession
of the Wealden beds.
In this same year, 1819, William Smith commenced the
publication of his ‘“ New Geological Atlas of England and
Wales,” a work which, like so many of his undertakings, was
unfortunately left unfinished. Two parts of this Atlas appeared
in the year named: the first, containing Norfolk, Kent, Wilts,
and Sussex, being dated January Ist; and the second, containing
Gloucester, Berks, Surrey, and Suffolk, bearing the date of
September Ist. In fulness of detail these county maps are far
superior to the corresponding portions of the map of 1815, and they
exhibit in not a few cases evidences of great advances in Smith’s
knowledge.
It was on November 1st of the same year that Greenough’s
Geological Map of England and Wales made its appearance.
A glance at this map will show that in many respects it exhibits
considerable advances in geological cartography as compared with
Smith’s map of 1815, or even with the later county maps. But
it must be remembered, as already pointed out, that the work
was really based on that of Smith, that for the Tertiary formations
and the strata below the Chalk Greenough had the invaluable
collaboration of Thomas Webster (who engraved the map), and that
for all the other parts of the country many of the Fellows of the
Geological Society supplied numerous very valuable contributions.
On February 1st, 1820, there appeared the third part of Smith’s
Atlas, containing the Maps of Oxford, Bucks, Bedford, and Hssex ;
and in the same year Cary, who published all Smith’s maps, issued
a “New Geological Map of England and Wales, reduced from
Smith’s Large Map, for those commencing the Study of Geology.” —
This map does not differ in any essential feature from the map
of 1815, from which it was reduced. The scale of the map is
nearly the same as that of a reduction of the Greenough Map,
published in 1826 by J. Gardner; and this latter map has been ©
frequently though erroneously ascribed to William Smith.
In the following year (1821) appeared the fourth part of the
Professor Grenville A. J. Cole—On Flame-Reaction. 103
Atlas. It is a very important work, namely, the Geology of
the County of York, in four sheets. This is one of the finest
of Smith’s works. It is full of admirably worked out details.
In the West Riding, the outcrops of the chief of the grit-beds
are represented on the map with their relations to the coal-seams,
and a fine vertical section of them is given; and in the north-east of
the county, Smith clearly defines the estuarine strata of the Lower
Oolites as follows: “Sand Rock and Grit Freestone of the Moors,
lying over the Alum Shale” (Upper Lias), “ and, in Scarborough
Castle Hill, under the Oolite or Calcareous Freestone. A thin coal
in the cliffs is worked on the Moors at Danby and other places.” In
this work we see the fruits of Smith’s residence at Scarborough,
which commenced in the year 1820.
The maps of Part V of the Atlas (Leicester, Netaneham Hun-
tingdon, and Rutland) were printed in 1821, but the part, according
to Phillips, did not make its appearance till 1822. Two years later
Part VI, with the Maps of Northumberland, Cumberland, Durham,
and Westmoreland, was issued, and this was the end of this very
important undertaking, though Phillips informs us that “ other parts
to complete this work were left in a state of forwardness.” With
the exception of a little “Synopsis of Geological Phenomena,”
a single folio sheet printed at Oxford in 1832 at the Meeting of the
British Association, the Geological Atlas of England and Wales was
the last of William Smith’s published works. It is perhaps not
generally known that the plates of Smith’s Atlas seem to have
been acquired from Cary by the well-known map-publishers Messrs.
Crutchley, and the sixpenny County Maps for many years issued by
that firm contain the lines and legends of William Smith’s maps.
In attempting to solve various questions that have arisen in
connection with the history of these early geological maps of
the British Islands, I have received much valuable assistance from
Mr. F. W. Rudler, F.G.S., the Curator and Librarian of the Jermyn
Street Museum. And to the same gentleman the Department of
Science and Art is indebted for the gift of a number of maps which
have proved to be of great value in making more complete the series
exhibited in the Science Museum.
I]l.—On toe Fuame-Reaction oF PotTasstumM IN SILICATES.
By Grenvitte A. J. Corz, M.R.I.A., F.G.S.,
Professor of Geology in the Royal College of Science for Ireland.
HEN recently examining a series of igneous rocks for the
Geological Survey of the United Kingdom, I required a ready
method for the determination of potassium in the felspars, whether
they occurred as porphyritic crystals or as microlites in the ground-
mass. The ordinary flame-reaction has always been recognized as
unsatisfactory in the presence of sodium, and the use of blue glass
has been long recommended, of a sufficient thickness to cut off
a sodium flame, the potassium flame then coming through alone.
104 ~=Professor Grenville A. i . Cole—On Flame-Reaction.
The blue glass usually supplied with blowpipe-cabinets is far too
thin, and any strong sodium flame will appear through it as a violet
one. On using blue glass 5 mm. thick, all but the strongest light of
an intense sodium flame is cut off, and the column or band of flame
that does reach the eye appears blue and not violet. On securing,
after experiment, a blue glass, or combination of glasses, which gives
only this effect, potassium may be safely looked for, and will readily
be recognized, even alongside the blue flame due to the presence: of
an unusual proportion of sodium.
Lithium, it may be observed, is cut off by a much less thickness
of blue glass, and can generally, as in lepidolite and spodumene,
be recognized by the eye alone, when the assay is held in the very
outermost sheath of the Bunsen flame, or barely touching the flame
at all.
The difficulty, however, in the case of potassium is that the flame
is often so feeble that some doubt exists as to its occurrence when
viewed through 5mm. of blue glass. Hence intensification has
been sought, in the case of silicates, by mixing the assay with
powdered gypsum, a method recommended by Bunsen. On thorough
heating, even 3 or 4 per cent. of potash reveals itself in this manner ;
and Professor Szabo! was confident that he could detect even
1 per cent.
The great value of Szabd’s results to geologists is their quantitative
character; but his determinations of potassium involve the dipping
of the assay into powdered gypsum, instead of its complete '
powdering together with the gypsum. The latter method I have
found to be far more certain ; but it is obviously impossible to pick
up again on the platinum loop, after powdering, the whole of the
assay selected, or a known bulk of it. Hence even the resuits with
gypsum have given little satisfaction in practice.
It seemed, however, that decomposition of the assay in a bead of
sodium carbonate might get rid of the difficulties surrounding the
reaction. We should always have the satisfaction of knowing that
what we saw could not be due to sodium, for this flame would be
eliminated by testing our blue glass in each case on the bead alone.
Moreover, the most refractory silicates would be dealt with even
more completely than when intimately powdered up with gypsum.
Since the simple support used in testing this reaction, and in all
such work in the laboratory of the Royal College of Science for
Treland, was described in the Geonocican Magazine,” it may seem
appropriate to furnish the details of this later process here.
The ordinary observations, as arranged by Szabd, may be gone
through first, on an assay of the dimensions used by that author.
In place of the observation with gypsum, I would venture to —
substitute the following. In many cases, such as the determination
of the presence of potassium in the groundmass of a lava, it may
suffice as the only observation to be made.
1 “Ueber eine neue Methode die Feldspathe zu bestimmen,”’ p. 34 ; Budapest, 1876.
* G. Cole, ‘‘A Simple Apparatus for Flame-Reactions’’: Grou. Mac., 1888, p. 314.
Professor Grenville A. J. Cole—On Flame-Reaction. 105
(i) From a crushed and pure sample of the silicate or groundmass,
select a bulk of about two cubic millimetres. This is about twice
the bulk used in the ordinary Szabo reactions.
(ii) Place the cone on the star-support round the lower part of
the Bunsen-burner, the flame rising some 15 cm. above it.
(iii) On the end of the platinum wire make a loop about 2mm.
in outer diameter; dip it into water—all ordinary waters are
sufficiently free from potassium—and pick up on it powdered sodium
carbonate. Fuse this into a bead covering the loop.
(iv) Examine the flame produced by this bead through 5 mm. of
blue glass, and note that the blue column in the flame has no violet:
fringe. :
(v) Remove the bead from the flame, dip it into water, and pick
up the selected particle or particles of the assay.
(vi) Fix the wire on the support, so that its loop falls in Szab0’s
position, in the edge of and enveloped by the flame, and 5mm.
above the top of the cone. Leave it for two minutes, noted by the
waich.
(vii) Then examine the resulting flame edgewise, i.e. with the
plane of the blue glass upright and parallel to the length of the wire.
If potassium is present, a violet flame will be seen, on the inner side
of the blue column produced by the intense sodium. The intensity of
colouration is as important quantitatively as the extent of the flame.
This flame is persistent for ten minutes or more, and may thus be
examined at leisure.
(viii) In some few cases, a further intensification may be required.
- Remove the bead, dip it into a drop of strong hydrochloric acid, and
insert again in the flame. The flames from the chlorides thus
formed rival those produced by the sulphates under the best con-
ditions of the experiment with gypsum.
I find it sufficient to tabulate the results obtained by the method
described in paragraph vii under three grades:—
Grade 1 = about 4 per cent. of potash.
» AS mo fe ” ”
” 3= ” 12 ” ”
I would advise each worker, however, to establish these grades
for his own eye and his own blue glass, upon specimens of known
and analyzed minerals.
Where only the qualitative result is required, the flame may be
viewed from the back, ie. along the platinum wire, when a violet
flame of varied intensity will easily be detected, occupying almost
all the region covered by the flame rising from the bead.
As examples of the use of the scale above suggested, the following
results may be quoted. The burner used was 9mm. in inner
diameter; the cone was 5cm. high, and its top was 8) mm. above
that of the burner; the flame was 18cm. high, and 145 mm. above
the top of the cone.
Grade less than 1.—Oligoclase, Ytterby. Flame just perceptible
in some experiments. Average of six published analyses gives
K,0O = ‘62 per cent.
106 Professor Grenville A. J. Cole—On Flame- Reaction.
Albite, Amelia Court House, Virginia. No result. K,O=°-43.
Albite, Zoptau, Moravia. No result.
Grade 1.—Apophyllite, Squire’s Hill, near Belfast. K,O probably
= 4or 5d percent. Analyses of other apophyllites give 3:10—6-30..
Biotite, Miask. This is a low result, but one analysis gives K,O
as low as 5-61, while the potash in biotite from other localities may —
sink to less than 1 per cent.
Grade between 1 and 2 (1:5).—Hleolite, Brevig. K,O = 5-17.
Eleolite, Magnet Cove, Arkansas. K,O = 5-91.
Anorthoclase, Pantelleria. K,O varies from 2:53 to 5-45.
Obsidian, Lipari. K,O= 5:1.
Pitchstone, Corriegills. K,O = 4:7.
Groundmass of Phonolite of the Schlossberg, Teplitz. The bulk-
analysis of the rock has K, O = 6°57.
Groundmass of Phonolite of the Schlossberg, Briix. This is full
of small nepheline crystals.
Grade 2.—Muscovite (probably Russian). K,O probably = 9 or
10 per cent.
Biotite, Burgess, Canada. Intensified to 25 by HCL K,O
probably about 8 per cent.
Grade between 2 and 3 (2:°5).—Porphyritic Orthoclase (Sanidine)
in trachyte of the Drachenfels, near Bonn. Average of five analyses
gives K,O = 9-7.
Groundmass of Phonolite, Schloss Olbriick, Eifel. Rich in
minute leucite crystals. Compare with the figures above given for .
phonolites rich in nepheline or nosean.
Grade 3.—Microcline, Pike’s Peak.
Orthoclase from drusy cavity in granite, Slieve Donard, Mourne
Mountains.
Orthoclase (Adularia), Schwarzenstein, Zillerthal.
Leucite. K,O = about 20 per cent.
Evidently all true orthoclases, with their K, O = about 13 per cent.
(theoretical 17 per cent.), come in grade 38. Soda-orthoclase will
give 2°5, and anorthoclase 1:5 or even lower.
Spodumene, with its good lithium flame visible to the naked eye,
gives no result through the blue glass used in these experiments.
Lastly, the advantages claimed for the employment of sodium
carbonate in place of gypsum are:—(1) The certainty in each case
that the sodium flame is clearly differentiated from that of potassium ;
we have a large quantity of sodium present, and we have eliminated
its effects. (2) Complete decomposition of the assay. (8) Security —
against loss of the assay when picked up on the moistened bead
and inserted in the flame. It is quickly fused in and absorbed.
(4) Since the operation is always performed in the presence of —
sodium, there is no need for elaborate cleaning of the wire after
each experiment, or for the use of distilled water.
Prof. H. G. Seeley—On Oudenodon from the Cape. 107
III.—On Ovprvopow (AvtLacocePHaLUs) PITHECOPS FROM THE
Dicynovow Brps oF Hast Lonpon, Carre Conony.
By H. G. Szetey, F.R.S., Professor of Geology, King’s College, London.
"ae genus Oudenodon of A. G. Bain, 1856, was adopted by Sir
Richard Owen, and defined as comprising Anomodont reptiles
of the type of Dicynodon, but absolutely toothless. Still, they were
referred to a family Cryptodontia, under the belief that the
teeth were immature and had their development arrested, so that
they never descended to the adveolar margin. A transition might
easily be made from the caniniform production upward of the
alveolar border seen in Oudenodon to the small teeth in Dicynodon
dubius and D. recurvidens, which are in contrast to the great lateral
ridges formed by the roots of the teeth in most species of the genus.
The species séirigiceps was referred first to Dicynodon and then
to Oudenodon. Owen described eight species, which differ from each
other in the elongation of the head, in the form of the preorbital region
and its prolongation in front of the nares, in the forms of the orbits of
the eyes, and the anterior nares, and in the median postorbital region
being either a sharp ridge or a more or less flattened concave
channel. These characters might have been used to define genera.
The species fall, more or less easily, into two groups, and this is
also true for Dicynodon. The same characters differentiate the
‘short-nosed from the long-nosed species of both types, suggesting
that the genera based on presence or absence of teeth in this case
are artificial. Thus, the short-nosed Oudenodons are almost in-
distinguishable except as species from the short-nosed Dicynodons ;
and the long-nosed Oudenodons similarly approximate in skull-shape
to the long-nosed forms of Dicynodon.
I therefore propose to divide Oudenodon into two subgenera.
The short-nosed types, with a wide flattened concave region
between the temporal vacuities, the parietal foramen in its middle
length, and orbits more or less circular and directed forward and
upward, are represented by the species O. Baini, O. raniceps, and
O. megalops. They may be indicated by the name AULACOCEPHALUS.
The prognathous species have the orbits more lateral, the parietal
foramen just behind the orbits, and a sharp median ridge between
the temporal vacuities which may extend along their length or be
limited to a part of it. This group is represented by the species
O. magnus, O. prognathus, O. brevirostris, and O. Greyi, and may
be indicated by the name RHacHIOCEPHALUS.
In the same way I would divide Dicynodon into two subgenera.
The short-nosed species have a broad concave parietal interspace
between the outwardly inclined faces of the postfrontal bones,
which make the inner borders of the temporal vacuities. The
parietal foramen is in the middle of this area. The nares are
scarcely seen when the skull is viewed from above, and owing to the
shortening of the snout the orbits are directed forward. The species
include D. Baini, D. tigriceps, and presumably D. testudiceps, and
may be defined by the name AULACEPHALODON.
108 Prof. H. G. Seeley—On Oudenodon from the Cape.
The prognathous type, with a median crest between the temporal
vacuities, includes the species D. lacerticeps, D. leoniceps, D. pardiceps,
and D. feliceps. They are grouped under the name RaacHIcEPHA-
topon. IThave no doubt that one-half of Oudenodon with the concave
parietal region should be closely associated with the similarly
characterized half of Dicynodon, and that the half of Oudenodon
with a parietal ridge should be associated with the Dicynodonis
which have the same character. Yet owing to the absence and
presence of teeth in the two groups there may be some convenience
in keeping the types distinct. In tabular form these species may
stand thus :—
OUDENODON.
Aulacocephalus. Rhachiocephalus.
Baini. magnus.
raniceps. prognathus.
megalops. brevirostris.
? strigiceps. Greyi.
Dicynopon.
Aulacephalodon. Rhachicephalodon.
Baini. lacerticeps.
tigriceps. leoniceps.
testudiceps. pardiceps.
feliceps.
Almost all these specimens were obtained from the Graaff Reinet
district and the Fort Beaufort district, at the time when Cape
Colony was expanding to the east, and Mr. A. G. Bain was engaged
in making military roads. The Aulacephalodon tigriceps is from the
Gonzia River, Kaffraria; and Aulacocephalus raniceps from Hast
London. As the strike of the beds is the same from Graaff Reinet
to Hast London, ESE., it is probable that these fossils occur upon
a definite geological horizon, above the zone of Pareiasaurus and
Tapinocephalus, and below the zone of Ptychognathus (Lystrosaurus),
near the bottom of the Middle Karroo, in what have been termed
the Beaufort Beds.
Many years ago Mr. McKay, of Hast London, sent to this country
_asmall collection of fossils from the black slaty rocks of the Hast
London district. Professor Huxley in 1868 selected one of these as
the type of the genus Pristerodon, described in the GroLogicaL
Macazine for that year, Vol. V, p. 201, Pl. XII.
The collection also included a small Oudenodon now catalogued in
the British Museum (Natural History) under the number R. 1819,
which is distinct from all described species and may be referred
to as Aulacocephalus pithecops. It is somewhat crushed, and is
remarkable for its small size, being only three inches long. It is
distinguished by the very large size of its nearly circular orbits,
which are placed in the middle length of the head, have a diameter
of => inch, and approximate closely to each other, so that the frontal —
interspace between them is narrower than the concave parietal area,
which is its hinder prolongation. The species is defined from
O. magnus by the concave parietal region; from that species and
Prof. H. G. Seeley—On Oudenodon from the Cape. 109
O. prognathus by wanting the anterior angle to the eye. It is
separated from 0. Greyi by the same characters, as well as by
wanting the large anterior nares of that species, and by having the
tamporal vacuities elongated from front to back. It has a relatively
longer nose than O. megalops, has not the eyes so far forward as in
O. Baini or O. brevirostris ; and the skull is much narrower than in
the Hast London species O. raniceps and differs in its proportions,
being of thin and delicate build, while O. raniceps has the bones
relatively strong.
Oudenodon (Aulacocephalus) pithecops, Seeley, sp. nov.
From the Dicynodont Beds of East London, Cape Colony. Restored from [R. 1819].
Preserved in the Brit. Mus. Nat. Hist. 4% less than natural size.
The skull is depressed, about twice as wide as high, and measured
transversely in front of the orbits, it is half as wide as long. The
preorbital region forms nearly an equilateral triangle, conical, rounded
from above downward and from side to side. Towards the extremity
of the snout, on each side there is a longitudinal depression, extending
from the orbits forward to the nares. Those openings were small,
and at present are obscured with matrix.
The orbits almost suggest the eyes of a lemur in their large
circular form; their chief direction is upward and outward. The
interspace which divides them is about one-third the diameter of
an orbit. The maxillary border extends back as far as the front
of the orbit, below which it is notched out and gives place to the
malar bar, which contracts a little behind the orbit from above.
In side view it is prolonged back parallel to the alveolar margin,
uniting in the usual way with the squamosal, and with the vertical
bar of the postfrontal bone which descends behind the orbit. The
external squamosal element of the zygoma is inclined obliquely
outward, and as it extends backward becomes deeper by ascending.
Jis upper edge is on a level with the base of the orbit in the malar
portion at the back of the orbit, but the concave upper outline of
the zygoma is on a level with the middle of the orbit, where the
arch terminates posteriorly. It is there inclined inward at an angle
110 G. F. Harris—J ourney through Russia.
of 45°, making the outer hinder angle of the head, which is its
widest part.
The upper surface of the skull suggests a sort of cruciform pattern
owing to transverse extension outward of the narrow bars of the
postfrontal bones which margin the back of the orbits. The parietal
region is concave from side to side, margined in length by sharp —
curved ridges which approximate towards each other in advance of
the middle length. In that narrowest part of the parietal the ovate
parietal foramen is situate. In those curved lateral ridges run the
sutures, which separate the flattened oblique posterior plates of the
postfrontal bones from the parietals, till near the squamosal, when
the postfrontal descends from the parietal ridge upon the squamosal
in the usual way. These oblong postfrontal plates make right angles
with the margins of the parietal bones to which they are external ;
they face towards the zygoma, and posteriorly the postfrontal and
zygomatic areas unite in a concavity which emarginates the squamosal
bone, and forms the upper lateral outline of the back of the head,
on each side of the narrower and shallower concave parietal area
between. The temporal vacuities are fully half as long again as
wide, and well exposed laterally owing to the low level of the
zygoma.
The brain-case appears to be closed by the usual bones which form |
the vertical occipital plate. They are slightly displaced. The
supra-occipital bone is quadrate and single. ‘The interparietal is
above it. There is no evidence that the exoccipital bones form the
occipital condyle in the way affirmed for Oudenodon raniceps, but
the exoccipital bones are large. There is no descending quadrate
pedicle, but the quadrate bone is short; and the articulation for the
mandible appears to be above the level of the occipital condyle,
though that structure is not clearly shown.
Seen from the side the superior contour of the head is gently
arched from front to back.
It will thus be evident that this species is distinct, and in some
details of the articulation for the lower jaw shows characters which
are exceptional in the group to which it belongs, though all the
short-nosed species have the skull depressed behind and wide from
side to side.
IV.—NaRRATIVE OF A GEOLOGICAL JOURNEY THROUGH Russia.
2. Finuanp (continued from p. 15).
By Gzo. F. Harris, F.G.S., M.S.G.F., ete.
ROCEEDING in a westerly direction from Tammerfors, we
stopped near the station of Siuro to examine some railway
cuttings where good sections of gneissose rock and mica-schist,
both of Pre-Bothnian age, occur. Macroscopically, the gneissose
rock is distinctly and regularly foliated, having small, lenticular, -
streaks of quartz abundantly disseminated. Locally, however, the
section in the field exhibits much contortion; and thin, irregular,
veins of quartz, manifestly of secondary origin, are not uncommon.
G. F. Harris—Journey through Russia. TL
Under the microscope this gneissose rock presents evidence of great
strain and mechanical movement. The quartz, the most abundant
mineral present, has been crushed to such an extent as to assume
a cataclastic structure, and nearly all the fragments show character-
istic mechanical deformation. In addition, the fragments have been
arranged in closely packed layers, and where the shearing proved
too great for them they have been broken through along these
layers; in the undulating cracks thus formed mica occurs in some
abundance. It is this structure which renders the rock so distinctly
foliate. Felspars are not common in my hand-specimens, and those
present are also much broken up. In one micro-slide, however,
I find a rather large fragment of a triclinic felspar, much altered
_ by crushing; it is too far gone to enable it to be satisfactorily
determined, but presents the general features of microcline. This
comparatively large fragment forms the nucleus of a lenticular,
augen-like structure, bounded for the most part by mica, interrupted
here and there by minutely crushed quartz which invaded the
nuclear area. Many of the quartz fragments in the rock exhibit
secondary enlargement.
This gneissose rock at Siuro occurs near the junction of mica-
schist with an immense massif of porphyritic granite.
The next section we examined was in the railway cutting, a little
to the west of the station of Suoniemi, where the Pre-Bothnian
mica-schist is well exposed. This rock presented no points of
special interest. It is reddish-brown in colour, fine-grained, and
well foliated. In thin sections, under the microscope, it is found
to consist of deformed angular fragments of quartz interspersed
amongst orientated minute films of sericite. Large masses of
muscovite occur in blocks by the side of the railway, but I did
not see them in siti.
Fie. 3.—Section in a ‘‘leptite’’ quarry, Mauri, Finland.
A railway cutting near Kulovesi showed an indescribable mixture
of schist and small veins of granitic rock, on the top of which were
a few feet of glacial clay said to be of marine origin, but we saw no
fossils. It was an impalpable mud of brownish-green colour.
Walking northwards from this place for a couple of miles, we came
to the hamlet of Mauri, and penetrating a wood found a most
interesting exposure (Fig. 3) of a rock called by Mr. Sederholm
112 G. F. Harris—Journey through Russia.
“leptite.” It may be described as a foliated arkose, containing,
however, much minute quartz. The rock is salmon-pink in tint
A conglomerate of the same material runs through the quarry
This has been severely dealt with; the metamorphic action which
rendered the sandstone foliated has drawn out the original pebbles
into long lens-shaped patches, the major diameters of which, in all
cases, are parallel to the folia. Macroscopically there does ‘not —
appear to be much mica; but micro-examination proves that that
mineral is fairly abundant in exceedingly minute flakes. To the
naked eye all the mica appears white, or bronze-coloured, though
thin sections of the rock demonstrate the existence of a little biotite.
Evidently the colourless mica has been produced at the expense of
alkali-felspars, and the felspathic constituents as seen in the rock,
as it stands at present, have largely become saussuritic. The larger
fragments of quartz are very interesting. If I dared use the term
in reference to a foliated rock I should say that they act as
phenocrysts, for that is exactly what they resemble when one
first glances at them under the microscope. They are scattered
amongst the exceedingly minute fragments of quartz, altered
felspar, and mica, which form a kind of groundmass, out of which
they stand conspicuously ; and they have been broken up into
small fragments by the crushing and shearing to which the rock |
has been subjected, whilst they present the usual phenomena of
cataclastic structure.
The evidence in the field is clearly borne out by micro-
examination. J wish we had had more time at this spot, for
I feel convinced that much light on an interesting phase of dynamo-
metamorphism would be shed by a careful examination of the
district. This leptite is foliated enough to place it beyond the
pale of an ordinary arkose, and yet not sufficiently to cause it to
be regarded as a true schist.
In respect to the relative age of this rock—unfortunately, its
junction with the schists near Kulovesi railway station is a fault,
and along that line of junction was the only hope of determining
its position with reference to the older rocks of the district. At
the same time, it is believed that it is younger than the granites of
the area, as these latter are brought up against, but-do not cut
through it. Following the classification detailed in the last
article, this leptite and conglomerate are distinctly Pre-Cambrian.
But they are, no doubt, much younger than the Pre-Bothnian gneiss.
The next day was devoted to an examination of some rocks
on the shores of Lake Nasi (Niasijarvi). We set out in two
enormous barges which had been decked over for the occasion,
and these were drawn by two very fussy little steam-tugs. It
is almost needless to say that nearly all Tammerfors came out
to see us off. After a boisterous passage to the other side of the
lake, our first point d’appui was the locality where “archean ~
fossils” are found. The landing, and then slipping over many
hundred yards of well-polished rock with beautiful glacial striae,
proved rather exciting, which excitement was considerably
G. F. Harris—Journey through Russia. 113
accentuated as two or three members fell into pools of water
conveniently arranged by Nature in big and deep holes in the
immediate vicinity of the ‘ Pre-Cambrian organic remains.’
The “archzan fossils” gave rise to an animated discussion.
There, on the smooth surface of the phyllades, we saw some
circular and ovoid markings outlined by black carbonaceous-
looking rings. Nobody seemed to know what they were, and it
is to be observed that no one even ventured to give them a generic
and specific name “ in order that they may hereafter be identified.”
Vague remarks about ‘fossil wood” ime. ‘impure phyllades ”
closed the visit to this spot.
Re-embarking, we went to an re in the lake, where
a remarkable phenomenon awaited investigation. I have said
(p. 15, ante) that the Bothnian schists in the neighbourhood of
Tammerfors are characterized by the presence of conglomerates
on several horizons. As we landed on this island the large pebbles
in one of these conglomerates, many of them 3 and 4 inches in
diameter, were very conspicuous, and the bed here cropping out must
be many yards in thickness. Although indurated, and to a certain
extent otherwise metamorphosed, this conglomerate is fresh enough
to enable each pebble to be clearly made out, or defined from
amongst its neighbours. On the beach the rock is much weathered,
and decomposition has set in on the surface of the majority of
the pebbles, which are pitted with small holes. Beautiful little
faults, having a throw of a foot or so, are seen in several places ;
they go right through the pebbles, and slickensides is not an
uncommon phenomenon.
The structure of this archean conglomerate exhibits a few
points of interest. In addition to the larger stones mentioned there
is much grit and fine quartzose sand, the grains of the latter being
angulate. The larger pebbles are for the most part fragments of
volcanic rocks presenting large phenocrysts of a triclinic felspar.
It is difficult to determine the precise nature of these volcanic rocks,
but in one of my micro-preparations there is certainly a small
pebble of « labrador porphyry.” The extinction angles of four large
phenocrysts of the felspar in this are + 34, ie. + 36, +35,
indicating labradorite. These phenocrysts, however, are much
altered and have many inclusions. The augite is not very
satisfactory and cannot be distinctly identified ; ‘T infer its former
existence by green decomposition products in small phenocrysts
having the approximate appearance of augite.
In ‘addition to these pebbles of volcanic rocks the conglomerate
is made up of pieces of rolled phyllade. Mr. Sederholm remarks '
that all the rocks represented by these pebbles crop out to the south
of the conglomerate, and there is, therefore, no reason to suppose
they have travelled very far. But he mentions some strangers
to the district as occurring therein, viz., ‘“‘ deux variétés de granite
ou syénite quartzifére, et une diorite quartzifére.”
1 Guide xiii, ‘*‘ Les Excursions en Finlande,’’ p. 4.
? ’
DECADE IV.—VOL. V¥.—NO. III. 8
114 G. F. Harris—Journey through Russia. -
Perhaps the principal point of interest in this Archean con-
glomerate is the change which some of the smaller fragments have
undergone. These adhere to each other for the most part, but here
and there is some well-developed granular quartz which acts as
a partial cement. The smaller clastic material consists of pieces
of plagioclase, fragments of uralitic augite, of quartz, and perhaps
of olivine. There has been a great deal of alteration and secondary
development in these fragments and the cement. That might have
been surmised from the condition of the augite, as just mentioned,
almost completely altered into uralite; whilst the olivine is partially
changed to biotite and similar products. Running through this finer
clastic material and the cement are roughly parallel lineations of
uralite, which is also seen bordering some of the larger pebbles.
It is accompanied by occasional minute flakes of biotite.
The rough attempt to produce foliation in this conglomerate and
much of the change induced in the pyroxene was doubtless brought
about by the same processes which converted the neighbouring
volcanic tuffs into uralite schists—for the conglomerates alternate —
with “beds” of these schists.
Leaving this interesting little island we went across the bay
of Hormistonlahti, and landed to make a further examination of
the conglomerates and to inspect the uralite schists. The whole -
of the rock is vertically disposed. These dark-green schists have
not been very much altered; their foliation is not conspicuously
marked, though distinct enough when closely examined. The
volcanic ejectamenta are small, but the fragments, as seen under
the microscope, are sufficiently large to enable their basic character
to be distinctly made out, and they do not seem to have suffered
much in the conversion of the tuff into a metamorphic rock. As
will be readily understood, the uralite is for the most part orientated
and is the principal assistant in producing the foliate structure.
This mineral is most completely formed, and actinolitic needles
are not only spread all over it, but project from its sides in
characteristic fashion. The needles also have a direction parallel
with the folia and impart a semi-fibrous aspect to the mineral.
A brisk walk along the beach enabled us to see that the uralite
schist was remarkably uniform in character for long distances ; I did
not observe any contortion in it. There appeared to be but few
exposures inland, a mantle of glacial beds spreading over the surface
of the ground and masking the solid beds beneath. But you cannot
see far in this part of Finland after you have left the lake-side.
The glacial beds give rise to a luxuriant vegetation, and though
the trees are not very tall they are sufficiently numerous and close
enough together to prevent one from observing much more than arises
along the immediate vicinity of the route traversed.
Regaining the barges, we made an earnest attempt to negociate
the lake; the little steamers did their best, and in a short time we
had covered 12 or 14 miles, in a northerly direction. Landing
again some few miles south of Teisko, opposite a grand section in
the glacial beds, full of boulders and small fragments of rock,
G. F. Harris—Journey through Russia. 115
we climbed a hill to examine an outcrop of granite. We also
got out to look at some diorite which has broken its way through
the granite. The outcrop of the diorite is very small, not more
than a few yards across; but the granite extends for hundreds of
miles over this part of Finland. It is the typical Post-Bothnian
granite alluded to ante, pp. 14,15. Thin sections show the diorite to
be a rather formidable compound ; for it is a quartz-mica-hornblende
diorite, the whole being much decomposed. ‘There is a considerable
quantity of opaque iron disseminated throughout, and my slide shows
both black and white micas, though the latter is very rare.
In a little time we arrived at the house of the hospitable
proprietress of Teiskola, the most northerly point of our journey ;
and later on the little tugs took us back down the lake some
20 miles to Tammerfors, sending myriads of sparks from the
wood fires flying out of the funnels on the way, the display
resembling ‘ fireworks” in the cold night air.
Up early the next morning, we trained to the station of Suinula,
a mile and a half from which place we visited an exposure of gneiss.
Farther on, along the railway line, near Orihvesi, we came to some
large railway cuttings exhibiting the contact between the Tammerfors
schists and the porphyroid granite. There seemed to be much
difference of opinion as to the precise nature of this junction,
which latter, however, was most clearly shown. Our Director,
Mr. Sederholm, said that the junction was “ mechanical.” In the
same section is a whiter granite, younger than the schists, which
often contains tourmaline.
The porphyritic granite contains many fragments of schist which
have been to some extent absorbed by it. The micro-structure
of such a fragment shows it to be a typical biotite schist, but having
a little white mica; the quartz is in small angular grains and
exhibits the usual cataclastic phenomena. Many of the larger
quartz crystals have been crushed in siti, the original boundaries
of each of these little groups being clearly definable.
Retracing our steps from Orihvesi to Halimaa, we went for a long
drive to Kangasala, where we made our first personal acquaintance
with asar. This gives me an opportunity for saying a few words
concerning the superficial deposits of Finland. The greater part
of the solid rocks of the country are covered by morainic deposits.
These are specially well developed, and form one continuous sheet
in the north, central, and eastern portions of the land. In the
south-central parts this sheet is much interrupted by innumerable
lakes, along the shores of which some of the best sections are exposed.
The country along the eastern boundary of Finland from near the north
of Sweden to the shores of Lake Ladoga is all mapped as ‘“ morainic
deposits.” They are a monotonous series of mixed gravels and
sands. On the other hand, in that portion of the country bordering
the Gulf of Bothnia and the Gulf of Finland, Glacial and Post-
Glacial clays are well developed, and crop out in every little river
valley for many miles inland. The greatest expanse of this
clay is to the south of Uleaborg, and in the immense tract of
116 P. M. Kermode—Cervus giganteus in the Isle of Man.
country to the north of Abo and Helsingfors. Near Uleaborg, also,
are extensive deposits of Post-Pliocene sand, smaller patches of
which are met with at intervals in the western parts of the country
and bordering the Gulf of Bothnia. In the interior of Finland
this sand also occurs, and large outcrops are mapped to the
north-east of Teisko and near Lake Ladoga, and on towards
St. Petersburg ; in the southern part of Finland, however, it is but
sparingly represented, and it does not appear to occur at all in the
northern part of the country above Uleaborg.
Perhaps, the most interesting glacial deposits of Finland are
the asar and stratified terminal moraines, which in some instances
stretch uninterruptedly for many miles across the country. We
had abundant opportunity of examining these at typical localities,
as will presently be described.
Confining attention to the neighbourhood of Tammerfors for the
moment, I may remark that the geologists of Finland are of accord
that glacial phenomena there are not so simple as in other parts
of the Grand Duchy. Messrs. Sederholm and Ramsay state! that
there are several systems of glacial strie. The predominating
directions are “S. 25°-30° H. et 8. 60°-65° H. (cété frappé au
N.-W.).” To the south of Tammerfors the striations run W.—-E., and
sometimes N. 65° EH. These diverse directions are explained as.
being formed during the retreat of the ice; but to the north of
the town there are strize running S. 5° E., and belonging without
doubt to a more recent system, which is connected with a large
terminal moraine found to the north-west of Tammerfors and which,
by its configuration and sandy composition, resembles an as. What
is believed to be the oldest system of glacial strize in the district is
in the country to the south of the town where the grooves run
N.and§. The morainic gravel throughout is remarkably uniform.
The glacial clays in the southern part of Lake Nasi are recognized
as marine “ Yoldiu-clays,” and there is also a fresh-water deposit.
(Zo be continued.)
V.—Tue “TIriso Hix,” Cervus GigANTEvs, In THE Isue or Man.
By P. M. C. Kermops, Esq.,
Hon. Sec. Isle of Man Natural History and Antiquarian Society.
N September last the Committee appointed by the British
Association to ‘examine the conditions under which remains
of the Irish Elk were found in the Isle of Man” commenced
excavating at Close-y-garey, near Poortown; but owing to the
unusual amount of water, considerable labour and expense were
incurred in the preliminary work of draining, and by the 25th
September the grant was exhausted.
Our local Committee thereupon took up the work, issuing
a circular for subscriptions, the response to which enabled them
to carry on the excavations with such success that on the 30th
1 Guide (op. cit.), p. 8.
P. M. Kermode—Cervus giganteus in the Isle of Man. 117
September portions of what appeared to be a perfect specimen
were disclosed in the undisturbed marl.
~The dub, or old marl-pit, in question, lies in a hollow in the
glacial drifts, about half a mile south of the Peel Road Railway
Station, on the east side of and close to the line. It had about
sixty years ago been worked for marl, and the present well-defined
banks mark out a rectangular hollow about three feet below the
surrounding surface, measuring about fifty yards square.
Across one corner of this a trench was dug to carry off the
water, and the operations of the Committee were confined to
a triangular area on the west side of the*trench, measuring about
15 yards east and west by 380 yards north and south. We
excavated all over this space to a depth of nine feet and more. The
first four excavations being through ground which had previously
been disturbed yielded no definite results, but at one point, about
10 yards from the north bank and 8 yards from the west, a few
elk-bones were met with in the disturbed soil. These and some
other bones were submitted to Professor Boyd- Dawkins for
examination, and he finds among them, belonging to this species, .
fragments of maxilla, the sixth cervical vertebra, the second lumbar
vertebra, and a fragment of a rib.
The last excavation, about the centre of our area, brought us to
the undisturbed marl at a depth of about three feet. On testing
this I found it to extend to a depth of 10 feet 6 inches at a point
about eight yards east of the bank, but four yards nearer to the
bank it did not reach a greater depth than eight feet. Between this
and the bank it appeared to have been disturbed.
In this bed of white marl, at a depth of about nine feet from the
surface, we found the remains of a complete skeleton, lying on its
right side, the head towards the bank, the legs drawn up to the
body. We considered it necessary to get it out the same day
(Saturday), as already many people had been to the place the
previous evening, and some one had broken off a piece of the
exposed antler. Had time allowed we should have endeavoured
to have cleared away the marl from around the bones and had
them entirely disclosed and photographed. Time, however, did
not allow of this, and as it was very wet we probably should not
have succeeded anyhow. Deemster Gill, Mr. Crellin, the Rev. 8. N.
Harrison, and I therefore took very careful note of the position of
the bones as they were gradually uncovered and removed.
So perfect was the skeleton that we had no difficulty in doing so.
The bones were nearly all in juxtaposition and in a fair state of
preservation. The left antler had fallen back over the lumbar
vertebre; it was rather decayed, the tines had fallen off, and the
beam was missing. The other antler had dropped down by the
cervical vertebra, and, except for the beam, was in good preserva-
tion, but in lifting it from the marl the tines dropped off. Un-
fortunately the skull had decayed away and only a portion of the
left lower jaw and fragments of the upper jaws remained.
The left antler is the larger; it measures across the palm
118 P. WM. Kermode—Cercus giganteus in the Isle of Man.
15 inches, allowing for a piece of the front edge which has decayed
away; the right measures 13 inches. With the tines restored, they
are respectively 564 inches and 53 inches long, and the beam would
have been at least 10 inches more. They show six points or tines,
besides the brow-tines, which had fallen off, the part where they
joined the beam having decayed away.
On laying the bones in position I find that the animal must have
been about 18 hands or six feet high at the shoulder. The fact of
its having antlers shows it to ihe been a male; and their size and
number of tines, that it was an adult. One of the ribs had been
broken, no doubt the result of fighting with another buck in the
rutting season, and had healed again. The teeth are in excellent
preservation, showing no sign of weakness or decay. The limbs are
perfect, all the small bones having, I think, been recovered ; the
vertebre also are sound and appear to be all present. The right
shoulder-blade, which lay beneath the other, is badly decayed, as
are many of the ribs, but I think they can be pretty well restored,
and, but for the missing skull and the beams of the antlers, the
bones when articulated and mounted will make a perfect skeleton.
Having secured this specimen, we continued our excavations in an
easterly direction, but very quickly got through the marl, and again
found the soil to have been disturbed as far as our trench.
With regard to the formation in which it was found, the British
Association Committee will no doubt have a full report for the
meeting at Bristol next September. The result of all the ex-
cavations, allowing for the very disturbed state of the ground,
shows the following beds :—
ft. ins.
A. Disturbed soil and peat, an average of about 3 0
B. In one place a blue clay or silt was observed resting on the
white marl.
C. White marl, containing the elk-remains ... on 6 6
D. Blue marl x ©
HK. Red sand with gravel 0 3
F. Brownclay .. en ee 0 3
G. Sand and gravel . : 0 3
Hcy \ ? Glacial drift roe
As stated above, the whole surface had been lowered about three
feet in digging for marl; the peat had for the most part been removed,
and a great deal of the marl also; indeed, we were fortunate in
finding this one spot in which the marl itself had not been disturbed.
The finding of detached bones shows that other individuals of
this species had perished here, and is consistent with what we were
told, namely, that a specimen had been seen when digging for marl,
and that the antlers of yet another had been taken out and sold.
We were told also that two skulls without antlers had been seen on
the east side of our trench.
Samples of the marl and other beds were forwarded to Mr. James ~
Bennie of Edinburgh, for preparation and microscopical examination,
and so far as we have heard, the peat appears to be an ordinary lake
peat, without anything very distinct about it. The marl contains no
G. P. Hughes—The Red-Deer in Northumberland. 119
fresh-water shells, but there seems to be a great number of Ostracoda,
also some Chara-seeds. The Arctic crustacean Lepidurus glacialis
and the Arctic willow Salix herbacea, which we found in our
previous excavations at Ballaugh, seem to be absent from this
section. Mr. Clement Reid, of H.M. Geological Survey, has kindly
undertaken the determination of the vegetable remains, and we hope
therefore to be able to give further information on the subject in our
Report to the British Association.
In recording this latest discovery of the remains of the great
deer, it is of interest to recall the fact that the first specimen to
have been set up, if not, indeed, the first almost perfect skeleton
found, is that now at Edinburgh, which was found at Ballaugh in
the Isle of Man in 1819. Altogether we have been able to trace
remains of about twelve individuals, and possibly more may yet be
met with, so that a herd of this noble beast must have existed here
after the kingdom of Man became an island. It is more easy to
account for its disappearance in so small an area than for its original
presence ; the best explanation of the latter being that suggested to
the writer by Mr. G. W. Lamplugh—that it had crossed over on
the ice.
It is somewhat remarkable that no other contemporary remains
have been met with, unless we may now except Hguus caballus,
some bones of which we found at Close-y-garey. From their
appearance Professor Boyd-Dawkins thinks these may possibly be
of the same age: most unfortunately they were only met with
where the soil had been disturbed, but they at least suggest
grounds for further search, which I hope we may be able to
undertake in the near future. ;
VI.—Nores on tHe Rev-Deer, Cervus ELAPHUS, LINN.’
By G. Prinete Huceuss, Esq.
M\EHE Red-Deer (Cervus elaphus), or common stag, is a native of
the more temperate regions of Europe, Asia, and North America.
In Great Britain it has its freedom limited to the Highlands of
Scotland, where, however, it is carefully protected, and affords the
créme de la créme of British field-sports to the practised rifleman
and mountaineer.”
In early English History, when the marauding disposition of the
people made cattle a precarious property, the wild deer. which
depastured the country in large numbers, afforded the staple article
of food. Large hunting parties were collected, and as many as
1,000 stags are recorded as having been taken at one of these
gatherings.®
The true stag and deer are at once distinguished by the presence
of deciduous branching antlers in the male, the female being in nearly
1 Read before the British Association, Toronto, in Section D (Zoology), 1897.
2 The shooting of some of the deer forests, of trom 25,000 to 35,000 acres, is let
for between £3,000 and £4,000 per annum.
3 The ballad of Chevy Chase records such a wholesale slaughter, though the
history of field-sports relieves the statement of any suspicion of poetic license.
AU) awe, Jee Jal ughes—The Red-Deer in Northumberland.
all cases destitute of such weapons. These appendages vary much
in character, being cylindrical or rounded in some species, and
flattened and palmate in others. They are bony outgrowths from the
frontal bones of the cranium, and, being developed periodically,’ have
an important physiological significance. An extraordinary supply
of blood seems to be provided for these bony outgrowths at the
spring of the year, and the vessels surrounding the frontal eminences
enlarge. This increased vascular action results in the secretion of
formative bony matter, producing a swelling or budding at the
summit of the frontal bones, at the spot where the horns of the
previous season had separated. In the early condition the horn is
soft and yielding, and it is protected only by a highly vascular
periosteum and delicate integument, the cuticular portion of the
latter being represented by various fine hairs, closely arranged.
From this circumstance the skin is termed “the velvet.” As
development goes on, a progressive consolidation is effected; the
ossification proceeds from the centre to the circumference, and
a medullary cavity is ultimately produced. While this is taking
place a corresponding change is observed at the surface. The
periosteal veins acquire a great size, and by their presence occasion
the formation of grooves on the subjacent bone. At the same time
osseous tubercles, of ivory hardness, appear at the base of the stem.
These coalesce by degrees, enclosing within their folds the great
superficial vascular trunks, which are gradually closed and cease to
flow. The supply of nutriment being thus cut off, the first stage of
excoriation is accomplished by the consequent shrivelling up and
decay of the periosteal and integumentary envelope. The full
growth of the antlers is now terminated, and the animals, being
aware of their strength, endeavour to complete the desquamation
by rubbing them against any tree or other hard substance that
may lie in their path. This action is termed burnishing. After
the rutting season the antlers are shed, to be again renewed in the
ensuing spring; and every year they increase in development, until
they attain their maximum growth.”
The fossil remains of deer, which have been plentifully found in this
country and the North of India, indicate that when unmolested by
man and in a wild state they attained a far greater size and probably
age than at the present day.
The period of gestation of the hinds extends over 8 months,
the young being produced in the month of May. During the winter
both sexes collect in vast herds; but in the rutting season the stags
1 «Tn the Deer (Cervide) the antlers consist wholly of bone which grows from the
frontals, the periosteum and finely-haired integument, called ‘ velvet,’ coextending
therewith during the period of growth; at the end of which the formative envelope
loses it vascularity, dries, and is stript off, leaving the bone a hard insensible weapon.
After some months’ use as such the horns, or more properly ‘antlers,’ having lost
all vascular connection with the skull, and standing in relation thereto as dead —
appendages, are undermined by the absorbent process and are shed; whereupon the
growth of a succeeding pair commences. The shedding of the antlers coincides
with that of the hair, and, with the renewal of the same, is aunual.’’—Ouwrn.
2 See Richardson’s ‘‘ Museum of Natural History.”’
G. P. Hughes—The Red-Deer in Northumberland. 121
frequently engage in the most desperate encounters, and sometimes
the antlers are inextricably fixed by the tines, both animals being
left to perish with interlocked weapons.
‘¢ As when two bulls for their fair female fight,
Their dewlaps gored, their sides all smeared in blood.”’
Virnein: A£ineid, xii, 715.
Antlers of Red-Deer, Cervus elaphus, Linn:
Found by G. P. Hughes, Esq., beneath a peat deposit, Cresswell Bog, eastern base of
the Cheviot Hills ; and preserved at Middleton Hall, Northumberland.
The specimen of which I submit a photograph is, I have reason
to believe, hardly surpassed for size and preservation by any other
examples from the peat deposits of Great Britain. The late Karl of
Malmesbury, who was for many years tenant of the Auchnacary
deer forest in Scotland, and moved among sportsmen of the first
rank at home and abroad, saw these antlers, in company with
another great sportsman and deerstalker and intimate friend of
Sir E. Landseer, the Earl of Tankerville, and was of opinion that
only in a few German collections in Hesse Cassel, etc., on the sites of
122. G. P. Hughes—The Red-Deer in Northumberland.
the vast forests of Franconia and Thuringia, where giant specimens
of Mammalia at one time abounded, would their equal be found.
I have, therefore, thought it desirable, as I have no descendant of
my own, to have this specimen photographed, and a copy sent to
some of our national Museums and Societies, in order to have the
existence of this fine pair of antlers of Cervus elaphus recorded in
proper form. |
MEASUREMENT OF THE ANTLERS PRESERVED AT MippLEeToN Hau, WooLER,
NorTHUMBERLAND.
-
3
me
mM
E
. Width from inside to inside of the crowns des B00
. Length of the beam to leading crown tine
. Width from outside to inside of beam at crown ...
. Circumference of the crowns (left)...
(right)
Rohr
+ .
Saap
5. Length of brow antlers (left)
(right)
m= oo co & Ob
6. Width of skull at stem :
7. Circumference of stem at base... 000 200
8. Number of points upon the two stems or beams ...
FOO O em ON
Dore
“This set of antlers, with several of less size, with entire skeletons
of red-deer measuring 15 hands in height, one foot taller than the
red-deer now extant, were exhumed from a lacustrine deposit of |
marl and peat known as the Cresswell Bog, at the eastern base
of the Cheviot Hills. The following is the section of deposits in
descending order as given by Mr. G. Tate, F.G.S., Secretary to
Berwickshire Naturalists’ Club :—(1) Peat, in which are prostrate
trees of hazel and birch, and also hazel-nuts: from 2 to 4 feet in
thickness. (2) Marl, in which have been found skeletons of
red-deer, teeth of the boar, and great numbers of fresh-water
shells: 8 feet thick. (8) Blue Clay, a few inches in thickness.
(4) Boulder-clay and gravel.”—Transactions of Berwickshire Nat.
Club, 1860. °
These facts give a tolerably clear history of the succession of
events at this spot. During the Boulder-clay period the district was
covered with water up to a considerable height. This period, with
its subarctic climate, its glaciers and floating icebergs, passed away,
and the present conformation of the British Isles was to a great extent
assumed. Where this specimen was found a small lake had been
left, in which for ages mollusks lived and bred, for the accumulation
of 8 feet of marl, chiefly formed of their shells, indicates a con-
siderable lapse of time. Deer and boar living along its margin,
or coming to it for drink, or, I may add, pursued by wolves or
Neolithic man, occasionally found a tomb beneath its waters and
yielding marl. In the course of time the waters were partly drained
off, but the ground being adapted for the growth of mosses, peat
was formed over the marl, and trees and bushes growing around
were time after time carried by floods and winds into the marshy ~
ground, which they have contributed to increase and solidify.
W. M. Hutchings—Rocks of Great Whin Silt. 123
VII.—Tue Conractr-Rocks or tHe Great Wuin SILL.
By W. Maynarp Hurcuines, F.G.S.
(Concluded from the February Number, page 82.)
N describing “ An Interesting Contact-Rock” (Grou. Mac., March
and April, 1895) I gave its analysis, showing :—
Potash ... 200 00 abo 500 boo 1-25 per cent.
Soda 200 900 600 see 500 eee 2°01 ”
And in this rock also the great relative increase in soda corresponds
with the appearance of albite among the new minerals.
But, as stated above, we also have cases of great alteration without
increase of soda; as, for instance, the two intensely affected shales
described from Rowntree Beck and Winch’s Bridge, both very rich
in alkali, and both showing still a normal excess of potash. And,
again, three other specimens of completely altered rocks from near
contact give :—
Potash ... ... 3°15 percent. ... 4°24 percent. ... 3°40 per cent.
Sodamiesemess L320 BS eee lige ie goo | OS7/ 99
Tn these the mica is all regenerated, with chlorite, as described, but
there is no sign of any new felspar.
Without burdening this paper with too many figures, I may say
that in between these extremes of great alteration of alkali-ratio,
and no alteration at all, come determinations giving an intermediate
result—soda has increased beyond the normal limits, but still not
to the extent of exceeding the potash, as for example :—
Potash... £3 ane iss 3°55 percent. ... 1°60 per cent.
Soda sue abs ae ae 2°20 es soo. alee a
If soda-transfer takes place, we should expect to find evidence
of it in the less pure sandstones, as well as in the shales, those with
argillaceous interstitial matter being really only diluted shales.
J have determined the alkalies in three specimens of altered sand-
stones, as follows :—
3 per cent.
2,
¢
ah ”
Potash om Os Zoe perrcentemen Ooo) pericentsy 2.102
Soda seer) 1 2046 Ss Aero talk As vee,
Here there is in each case a very decided excess of soda, and
the total alkali contained is much more than would be expected in
consideration of the relatively small amount of original argillaceous
material. These determinations, as far as they go, would strongly
countenance the idea of transfer of soda in some form, and tend
also to show that the sandstones have taken it into combination,
and held it, out of proportion to the shaly deposit contained in them.
Tests of some of the limestones have also been made, for the
same reason, that where less pure they contain argillaceous material,
and should show the alteration of alkali-proportion if it has taken
place. Of the following two analyses, A represents a specimen from
within a few inches of contact, containing a quantity of garnet and
124 W. MW. Hi Wecrngnee Rocks of Great Whin Sill.
a good deal of recrystallized silica. B is a rock practically free
from minerals other than calcite—only a very few garnets and
a little quartz :—
AN B.
SMG, cas én 300 dae 40°90 percent. ... 4°60 per cent.
Alumina eat Ms is 5°45 ap Boo os se
Ferric Oxide... yee wise 7°88 4 soo ONES) if
mee es eases Nh eer a 99.40) 2 SOO eee
Magnesia we 660 Bbc 2°17 39 loo 5
otashweres i ee B56 0°28 a BS me OLS) FS
Sodaiyeee: ne ae ce 0-74 50 sce MPG 30
Carbonic Acid ... van oe 10-06 ss ooo) wi iY) 3
Water... axe aoe 5n0 2°80 a ton, PNG ae
99°67 100°87
A portion of B was dissolved slowly in dilute cold hydrochloric
acid, the residue filtered and dried, and its alkalies separately
determined. It gave :—
Potash ... are 560 aa has a 0°35 per cent.
Soda a : 0-78
”
Another limestone, completely recrystallized, and showing grains
and small indeterminable crystals of foreign matter, gave :—
Potash ... oe was ae aes isa 0:26 per cent.
Soda wee ab Soe sis Gee as 0°81
”
This rock, dissolved in dilute acid, gave a residue which, after
filtration and ignition, was 6 per cent. of the original material, and
contained :—
Potash ... noe See 545 ood bc 0-58 per cent.
Soda ae 006 ee : 6°30
ue}
All the above show large excess of soda, but amongst the lime-
stones, also, we find contradictory results. ‘Thus, one altered bed
containing augites, etc., gives :—
Potash ... 300 209 a0 200 bo 2°55 per cent.
Nodame nee. 200 200 250 350 009 0°62
22
Another hand-specimen shows sugary white limestone, together
with a layer of brown hornfelsy rock, due to impurer material.
The alkali-contents are :—
White Limestone. Brown Layer.
Potash ... sed ay 0°30 percent. ... 5°79 per cent.
Sodaa ss. BB Ae 0-07 a soa LO sa
At my request, Mr. Garwood collected a series of specimens
representing the succession of beds downward from the Whin Sill
to the basement conglomerate, at Falcon Clints, in Upper Teesdale ;
as I thought it would be of considerable interest to make alkali-
determinations in them, and at the same time examine them micro-
scopically and note the nature and intensity of the alterations.
The particulars of the section at this point, as given to me by
Mr. Garwood, are as tollows :—
W. M. Hutchings—Rocks of Great Whin Sill. 125
WuHin Sitt, 100 FEET THICK. Feet thick.
No. 1. Limestone, with garnets, etc., where impure ;
white and sugary where pure, but containing
patches of altered shaly matter, sandstone, ete. 24
No. 2. Shale, weathered ... axe see ee ea 12
No. 38. Limestone ... See a Woe ae ee 10
No. 4. Shale, weathered tee ae ae 6
No. 5. Limestone ... 0 aa Pon A ae 2
No. 6. Sandy shale : 3
No. 7. Limestone, hard blue, with fossils 8
No. 8. Flaggy sandstone ... : 10
No. 9. Shale with nodules.. ; skis 8
No. 10. Basement conglomerate es B06 2
Total of sedimentary beds 88
The specimens examined gave results as follows :—
No. 1.. This limestone has been described above, so far as concerns
the garnet and idocrase-bearing hornfelsy alteration-product, of which
an analysis was also given. This analysis showed a large excess
of soda. But it was another hand-specimen from the same locality,
with both pure limestone and a layer of the hornfelsy material,
which gave the figures just quoted, showing potash in large excess
over soda.
In this limestone-bed occur patches and lenticular masses of
altered sandstone and shale. A specimen of such a sandstone shows,
in the sections, that it is rather coarse-grained, with a good deal
of interstitial matter of originally argillaceous nature, with fine-
grained quartz. This matter is all intensely altered, showing some
newly-formed mosaic of quartz and a little felspar, a lot of white
mica in beautiful tufts and bunches, and here and there patches
of newly-crystallized, glassy-clear groups of well-twinned plagioclase
crystals, some of them identifiable as albite. The alkali-contents
of the rock are :—
Potash ... ac 206 doe Bo tee 0-55 per cent.
Soda ae Bi a: sae ae eis 201 a
A patch of shale from the same source shows alteration on the
usual lines—much of the indefinite new “speckly ” product, white
mica, chlorite, etc., with “spots” containing more chlorite, less
mica, and great aggregations of rutile grains. It contains :—
Potash ... adie a Bod dos ee 4°82 per cent.
Soda ee ae a3 oa Ho tas 1°48 a
No. 2. This was a ciency quartzy shale. The quartz is
not much affected, but the main mass is greatly altered, chiefly
to speckly matter and white mica, the latter often forming clear
patches and circular spots of larger, clearer flakes of muscovite, or
of muscovite and chlorite. The rock contains :—
Potash ... a0 299 as bbe be 5°36 per cent.
Sodayuuen: BBC ae oe Ba soc 2°93 ‘es
No. 3. Limestone, originally impure with argillaceous matter.
The bulk of it is not highly altered, not even rendered coarsely
126 W. MN. Hutchings—Rocks of Great Whin Sill.
crystalline. But there are many “spots” in the sections, in
which, among a good deal of indeterminable matter, some chlorite,
etc., are a good many small bits and prismatic crystals of augite.
Some augite occurs also outside these spots, but not much. ‘The
alkalies are :—
Potash ... 200 500 506 aye ooo 2°55 per cent.
Soda) sec. di dae sas us ee 0°62 a
No. 4. A main mass of fine-grained shale, in which are bedded
good large quartz fragments, with numerous flakes of clastic mica,
and a good many grains of calcite. The coarser constituents are
not altered, but the finer portion has been completely regenerated,
giving rise to a small-grained dim sort of mosaic, with a little new
mica, and showing here and there larger patches of this and of
chlorite. This rock contains :—
Potash ... did 900 Se ae ate 3°55 per cent.
Soda tre me ie sts Hest Ss 2°76 is
No. 7. This limestone is very much recrystallized, but does not
show any distinct new minerals, being only slightly impure :—
Potash ... Se 500 300 260 oon 0°26 per cent.
Soda ae ae aa S00 ios wa 0-81 a
No. 8. A sandstone converted into a quartzite. There was very —
little interstitial matter, which is now much altered, but details
cannot be made out :—
Potash ... es a ah 500 wis 0°23 per cent.
Soda wee Ke ae aoe au as ely a
No. 9. This is the bed described as “an interesting contact-
rock,’ the main characteristics of which were recapitulated above,
so that no description need be given here. It was pointed out that
the bed varies more or less in composition in different parts, being
more or less quartzy, etc. As since IJ first described it I have made
some more alkali-determinations on various specimens, it may be
worth while to add them here :—
per cent. percent. percent. percent. per cent.
Potash... 556 WON ono | OPE son | NGO 5 BP oon OO
Soda 2: a0 EO cog) PIM) Wee iIE Gag | WS) cog «WBS
The last is from a sample representing a large number of the
‘“‘nodules,” which were carefully detached from the rock.
We do not know how far from the contact the metamorphism
caused by the Whin Sill was capable of extending, but we have here
an instance of very great alteration at over 80 feet distance, and
may safely say that the action would have continued much further. —
From published observations on the subject, it does not seem usual
for the contact-zone of basic dykes or sheets to be as extensive
as this.
The interpretation of the chemical determinations above given
does not seem to be an easy or a satisfactory business, owing to
their contradictory nature. Many of them show an undoubted
access of soda, at least—that conclusion seems to be unavoidable,
W. WM. Hutchings—Rocks of Great Whin Sill. 1G
unless if can be shown that there are shales, and argillaceous sand-
stones and limestones, among the Lower Carboniferous beds, and
indeed in the particular districts in question, containing soda in
some such ratio to potash as is disclosed by these determinations.
On the other hand, it is difficult to explain the fact that such soda-
rich alteration-products alternate with others, derived apparently
from quite similar original rocks, in which, as we saw, soda has
not increased, or has increased in a far less degree.
Supposing some compound of soda to pass from the igneous
magma into the invaded beds, we can readily explain to ourselves
how it could come about that purer limestones show little or no
trace of its action. Solutions containing this compound of soda
could permeate the limestone, and pass into beds of shale, ete.,
beyond it, without being in any way permanently taken up and
combined with it; and in course of time the limestone would be
freed from the merely mechanically held soda; whilst in the
complex silicates of the shales would be offered a material with
which introduced soda would easily enter into new and permanent
combinations. But we cannot very well explain how it is that one
bed, or part of a bed, of shale takes up so much more than another.
We must leave this, for the present, as one of the many things
which we cannot yet make clear.
Looking at those rocks which show a considerable amount of
soda-felspars, and carefully observing the part these felspars play
in the structure of the rock, and their relationships to the other
minerals, it does not seem possible to conclude otherwise than that
the soda-increase and formation of these felspars and these structures
were all part of the one process of contact-metamorphism and
recrystallization of the rock-constituents. No later introduction of
soda, by percolation of solutions from the cooled and weathering
igneous rock, is at all consonant with what we see. And this is
equally true of those beds in which, though we find soda in excess,
we cannot detect any felspar with the microscope, and are led to
assume that the soda is combined in the abundant new mica
developed, in the “speckly ” intermediate material, and in other
new products.
In this rather indefinite and unsatisfactory position we must,
apparently, leave this part of the subject for the present, at all
events so far as the Whin Sill is concerned. Having devoted
a good deal of time and trouble, both to “looking it up” elsewhere,
and to trying to obtain evidence from our most favourable British
opportunity of studying it, 1 make no apology for dealing with it
at some length, even though, unfortunately, not conclusively. It
touches one of the most important points which still stand first for
consideration on our way to an understanding of the true nature and
processes of contact-metamorphism.
Incidentally, it is worth pointing out that the series of alkali-
determinations given above, supplementing as they do my previous
analyses of fireclays and shales, quite definitely dispose of the
contention, often put forward, that none of these deposits contain
128 W. MM. Hutchings—Rocks of Great Whin Silt.
enough alkali to justify the belief that they could be the early
material of true clay-slates, ete.
It is not, however, in this chemical question, nor yet in the mere
cataloguing and description of the new minerals produced, that
the great interest of the contact-rocks of the Whin Sill is centred.
This interest mainly lies in the observation of the nature of the
structures produced, and the relationships of the minerals to one
another; and in the comparison of these structures with those of
rocks from great contact-areas round granite intrusions, as well as
with those of others, of similar composition, which have been
subjected to intense dynamic and deep-thermal conditions, but not,
so far as we know, to the action of any intrusions of igneous masses.
When a shale is highly altered by contact with the Whin Sill, we
get in most cases, as has been shown, a splitting-up of the complex
micaceous mineral of which it largely consists, into a purer, more
highly developed white mica, which we may in general designate
as muscovite (though to some extent it may consist of paragonite
or of an intermediate stage), and into a chloritic mineral. Both the
mica and the chlorite crystallize in the rock in all directions, quite
irrespective of the stratification-plane in which the original micaceous
minerals lie flat. A certain criss-cross structure is at once produced ;
it commences as soon as the contact-effect is noticeable at all, becomes
more and more pronounced in the more highly developed cases,
and is often accentuated by the formation of rosettes and sheaves
of mica and chlorite. These effects and appearances are all the
more striking because they are produced on an original material
of such low development. We pass at one step from a rock with
no white mica, no chlorite, and no criss-cross structure, to one in
which all these things are in full evidence. At granite-contacts
we may often see exactly the same products in the altered rocks,
but they are then frequently, in that sense, not so striking; because
in most cases the rocks acted upon have been in a much higher
stage of development; they were not elementary shales, but slates,
in which a good deal of formation of mica and chlorite had already
taken place. The final result is, however, the same in both cases,
and is also the same whether the granite acts on a mere shale or
on a slate; we get a pure white mica, and a corresponding
separation of chlorite or its equivalent in biotite, cordierite, etc.,
all crystallized in every direction in the rock.
To make out the minerals and the structures in the Whin Sill
rocks we may need high powers, whereas we may see all these
things with low powers, or a pocket-lens, in the sections from
a granite-contact; but this is a matter of no importance, and is —
related to nothing beyond the respective bulks of igneous rock
concerned, and probably also the greater or lesser depths of the
invaded rocks, with corresponding differences of their initial tem-
peratures. The same considerations apply also to the frequent
abundance of certain special minerals at granite-contacts, and their
absence, or rarity, in the Whin Sill rocks. Leaving aside these
conditions of mere size and intensity, the results are strikingly
W. M. Hutchings—Rocks of Great Whin Sill. 129
parallel ; and a concurrent examination of a series of rocks from
the two sources does not fail to impress one with the idea of how
relatively slight and mild a degree of contact-action is required 1o
bring about certain very definite and characteristic effects. I have
compared these Whin Sill rocks over and over again with contact-
rocks from several localities, and quite recently, whilst once more
passing them in review in connection with the putting together of
these notes, I have had the opportunity of looking at them side by
side with a fine series from Scotland. One can often pick out
examples of both, which, barring certain minerals (as e.g. kyanite),
are so exactly similar in structure and general nature, that the slide
from the granite-contact might be almost imagined to be derived
from one from the Whin-contact by some process akin to photo-
graphic “enlargement,” every detail being reproduced.
But, on the other hand, we may compare these Whin Sill sections
with any number of examples of rocks which have suffered the most
intense degrees of crushing and shearing, and which have been
under enormous depths of cover, without being able to find in
these latter any signs of even a commencement of the characteristic
structures, or more than a very moderate amount of the mineralogical
development. Such rocks as these, as I have shown in former
notes (e.g. Guont. Mac., July and August, 1896), certainly display
a decided degree of advance beyond the clays and shales from which
they started. We have the formation of new mica and of chlorite,
going along the same chemical and mineralogical lines as in contact-
action; but it does not seem to be able to pass beyond relatively
moderate limits, giving us a still impure mica. And in the matter
of structure the limits are still more restricted. We do not get
beyond a felted and wavy mass of mixed mica and chlorite; there
is no growth of crystals of mica at all angles and in all directions,
no criss-cross structure, no rosettes and sheaves, and no sign any-
where of crystallization of chlorite. Neither do we ever see any trace
of the amorphous, or semi-amorphous, and speckly material passing
upwards into definite mica, etc., which I have pointed out as so
frequently characteristic of rocks which have recrystallized under
contact-action. Nor do we see in such rocks any trace of biotite
or other special minerals which we know so well in contact-rocks.
Yet all these things which we may thus find to be absent from some
most ancient sedimentary rocks after they have had every allowance
of time, dynamic action, and depth-conditions, we see can be pro-
duced in similar materials, almost instantly, as it were, by the
action of a relatively insignificant amount of igneous magma
intruded among them; the evidence in the special case before us
being quite beyond the possibility of confusion or question, as to
the fact that these effects are wholly due to the intrusion and to
nothing else, and thus much simpler and clearer than often is the
case in granite areas.
These observed facts, and the considerations arising out of them,
duly weighed, seém to lend a reasonable degree of probability to
the conclusion I have suggested on other occasions, viz., that so
DECADE IV.—VOL. Y.—NO. III. 9
130 W. M. Hutchings—Rocks of Great Whin Sill.
far as our present actual knowledge goes, there are structures and
mineralogical developments which, whenever we see them, even
in moderate degrees of evolution, we are not only justified in
ascribing to contact-metamorphism, but which we have not an atom
of reason or evidence for attributing to any other cause, no other
cause having as yet ever been proved to produce them; and certainly
not dynamic action, as to which we can collect plenty of very clear
evidence that it has failed over and over again to bring about even
the beginnings of them, under the very circumstances which ought
to be most favourable for its doing so.
When we look at this matter quite calmly, it certainly does seem
rather strange that the “blessed word” dynamometamorphism has
been allowed to exercise such a spell over our minds in directions
in which it can hardly be said to have ever made good its pretensions.
Here were rocks of sedimentary origin, showing very great and
striking mineralogical developments. They aiso showed beyond
question that they had undergone great dynamic action. Therefore
the latter was the cause of the former. In how many cases
has there been but little better evidence than this to support its
all-embracing claims, which were made to explain everything
without proper proof! And at the same time we have, all around
us, examples of the fact that what dynamic action has been asserted, ~
but not proved, to do, is done not only by every great intrusion of
granite or other igneous rock, but by even quite small intrusions also.
Let a great area of sedimentary rocks be altered by the action
of igneous masses which we cannot see; then let powerful dynamic
action follow, and there we have at once a fine example of the
marvellous recrystallization and formations of new minerals which
dynamic metamorphism has brought about, shutting our eyes to
other cases in which even more intense action, on similar materials,
has effected practically nothing of the sort.
If we take simply what we at present know, and can prove over
and over again, and separate it from what is certainly not at all
proved, no matter how strong the a priori evidence may sometimes
appear, it would seem to be quite reasonable if we were to regard
certain microscopic structures of altered sedimentary rocks as
probably indicating that the alteration took place under the influence
of contact-metamorpbism, no matter whether we can actually see
the igneous rock concerned in it or not. On a similar line of
reasoning from what we know, we might also draw the same
inference from the development of certain minerals in such rocks,
not only the specially so-called “contact-minerals,” but others as
well. Thus, the presence of undoubtedly newly-formed biotite in-
altered shales and slates should point the same way, till we have
some evidence that any other process known to us can be proved
to have the power of producing it. And it might even not be
going outside the safe ground of induction if we were to include ~
very highly developed and individualized muscovite, and certain
forms of chlorite, under the same head.
‘)f these several points, that of structure certainly appears to be
Notices of Memoirs—Lyman on Compass Variation. 181
the most important, and the safest on which to rely, whenever we
find it. But we know that dynamic action may have more or less
completely effaced this structure, and in a great number of cases
has done so.
We know on what lines this effacement proceeds, and with what
sort of new structures it replaces those it has modified or destroyed.
It is, however, not uncommon to find that, even in greatly affected
“dynamic” areas of this description, the action has not embraced
the whole of the rock, and from among rolled-out, sheared, and
puckered schists, may come specimens showing, more or less per-
fectly, the contact-structures which we seem to have good grounds
for always recognizing as such. |
ISPFOQLwGwEHS) (Ougy Ive yMa@alisytS
Compass VARIATION AFFEOTED BY GEOLOGICAL STRUCTURE IN
Bucks anpD Montgomery Countiss, Pa.’ By Brensamin Smite
Lyman.
HE Journal of the Franklin Institute, October, 1897, contains
an interesting paper by Mr. B. Smith Lyman, formerly State
Geologist to Japan, describing a remarkable coincidence between
the axis of a set of curves of magnetic variation in Bucks and
Montgomery Counties, Pennsylvania, and a great deep-seated fault
in the New Red strata below ending westwards in the axis of an
anticlinal fold. Both the curves and the fault are shown on an
accompanying map. From this paper we extract the following
passages :—
The magnetic curves were mapped some years before the
beginning of the recent Geological Survey, that for the first time
fully proved the peculiar structure ; but the curves had no influence
whatever in the interpretation of the geology, and the correspondence
was not perceived until long after the geological map was printed.
The magnetic map was made about the year 1883, by the Water
Department of the city of Philadelphia, for use in its excellent
topographical survey of the Perkiomen and neighbouring valleys
under Mr. Rudolph Hering. The map records the results of
a number of determinations of the magnetic declination made by
the Water Department itself and by the Coast Survey and by other
observers, and curves of equal declination were drawn for every
tenth of a degree. The curves are so extremely at variance with
the simple, nearly straight lines of earlier, less detailed maps, as
either to show extreme confidence in the accuracy of the observa-
tions, or perhaps even to excuse a suspicion of the possible incorrect-
ness of the curves in some way, especially in view of the
acknowledged want of precision of some of the observations, and
the absence of any obvious topographical or other occasion for such
1 Reprinted from the Journal of the Franklin Institute, October, 1897. | Mining
and Metallurgical Section: Inaugural Meeting, held April 28th, 1897.
182 Notices of Memoirs—Lyman on Compass Variation.
great irregularity. But the curves are in the main beautifully
confirmed and thoroughly vindicated by the underground geology.
The striking feature and dominant peculiarity of the curves is
a very strong bend convexly north-eastward near New Hope and
Lambertville, on the Delaware; but gradually changing towards
the west, so that the curves near Shwenksville and Boyertown point
still more sharply south-eastward. The axis of the bend in the
curves is, then, itself greatly bent, nearly to a right angle. The
Geological Survey of the two counties, begun at the end of 1887,
has proved beyond a question the existence of an enormous fault,
of about 14,000 feet, in the rock beds, almost precisely on the
line of the Delaware River end of that magnetic axis, and
following the same course past Doylestown, gradually dying out,
and west of that town turning north-westward, passing north of
Shwenksville, disappearing there as a fault, but continuing as
a sharp anticlinal to the border of the New Red and of Montgomery
County, 5 miles north-east of Boyertown.
The geological structure of the map of 1893, published by the
State Geological Survey, was drawn without the least reference to
the magnetic curves, and, indeed, without any knowledge at that
time of the slightest correspondence between them and the geology.
The geological map gives the direction and amount of the dip at —
a couple of thousand points, amounting to a complete demonstration
of the structure, and to a full proof of the situation and extent
of the fault and of the sharp anticlinal into which the fault runs.
The topography also given on the same map shows that there
is no one strongly-marked ridge following the course of the axis
of the magnetic curves. Indeed, there are more decided topo-
graphical indications in the way of long, rather high ridges in other
directions. Furthermore, the form of the outcropping rock beds,
sedimentary or igneous, does not correspond in any degree with the
magnetic curves.
Moreover, some light is perhaps thrown upon the obscure subject
of terrestrial magnetism. It is true, the nature of the relation
between the magnetic and geological phenomena is not so easily
determined; but it seems to become certain that the internal
structure of the earth’s crust has an important influence upon
terrestrial magnetism, even if it be not in any degree its first cause.
Terrestrial magnetism and its changes have sometimes been con-
sidered explainable by solar influences alone, no longer by direct
action of the sun as a magnet, but by the sun’s heating the
atmosphere or the earth’s crust. The present phenomena seem,
however, to point to more strictly terrestrial processes as the true.
cause, and to suggest that the solar influence may partly at least
be exerted through the attraction of gravitation as well as through
heat. The enormous and locally unequal strains produced by the
contraction of the earth’s crust in cooling would be particularly”
liable to be affected by the presence of a deep fault or by a sharp
anticlinal. Such lines would be places where the crust has yielded
and is readier to yield, and consequently where the strain has
ai pees!
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Reviews—J. G. Millais—British Deer. 1338
been to some extent relieved and is less. The recent occurrence
of earthquakes along the New Jersey end of this very fault-line
shows that the resistance there is less, and that the remaining
strain must likewise be less. On such a comparatively weak
yielding line the rock beds in readjusting themselves, even where
‘there is no violent earthquake, must occasion a certain amount,
not only of strain, but of friction and heat that might give rise
to electrical currents. A decided magnetic effect, too, has sometimes
been observed to accompany earthquakes, and in some cases to
precede them. In like manner, the strains and yielding or readjust-
ment that may be occasioned by the attraction of the sun and moon
might apparently cause electrical currents; and, in fact, magnetic
disturbances have been found to correspond, like tides, with the
place of those heavenly bodies. Again, the broken or arched
form of the rock beds may permit at least a temporary local
‘variation in the temperature of the crust, as affected by the
earth’s hot interior, that could occasion electrical earth currents.
Terrestrial magnetism seems, then, to arise not only from the manifold
action of the sun’s heat upon the air and the earth’s crust, but
from the internal movements of the crust and from the tidal
effect of the sun and moon upon the air, ocean, and solid earth.
The author does not admit that the magnetic curves could have
been produced by any known deposits of iron-ore or trap, near or
distant ; comparing such an idea to the ancient Oriental tales of the
loadstone that drew men’s boot-nails, or the seaside mountain that
pulled the bolts out of ships’ sides. He adds :—‘“‘ Deposits of
magnetic iron-ore, though differing much in magnetic force, seldom
directly affect the most delicate magnetic needle at a distance of
more than a few hundred feet.”
154 dH WA de den WW Se
British Deer anp THEIR Horns. By Joun Guitie Mitzats,
¥.Z.8., ete. With 185 text and full-page illustrations, mostly
by the Author, assisted by Sidney Steel, two by H. Roe, and
photographs; and a series of unpublished sketches by Sir
Edwin Landseer. Imp. 4to; pp. xviii and 224. (London:
Henry Sotheran & Co., 37, Piccadilly, and 140, Strand, W.C.
1897.)
(PLATES III AND IV.)
R. MILLAIS is already favourably known to the public as
the author of ‘‘Game-Birds and Shooting Sketches” and
“ A Breath from the Veldt,” both rich in illustrations. Although
a thorough sportsman, and, like his father, the late Sir John Everett
Millais, Bart., R.A., a born artist, Mr. John Guille Millais com-
bines with these qualities sufficient of the true naturalist and
palezozoologist, to lead him in his “History of British Deer
and their Horns” to enter upon a brief account of the ancient
types of deer which inhabited these Islands in prehistoric times,
134 Reviews—J. G. Millais—British Deer.
and whose skeletons and antlers preserved in the British Museum
(Natural History), Cromwell Road, or in other kindred institutions,
now form their only record. Many of these Mr. Millais has
sketched with commendable fidelity. It is difficult to separate
the extinct Alces latifrons, found in the Cromer Forest Bed and
at Happisburgh and Corton, and on the Dogger Bank, from the
living elk (Alces machlis) found subfossil at Cleveland, Yorkshire,
and in about thirty-one English, Scotch, and Irish localities, and
which still survives in Norway and in Canada.
To the same northern category also belongs the reindeer (Rangifer
tarandus), which is recorded from more than eighty localities
in this country, is still living in Northern Europe, Asia, and
America, and is believed to have survived in Caithness until the
middle of the twelfth century. Of fossil varieties of the true deer,
Cervus polignacus, C. Brownii, and ©. Savini, little need be said.
They are forms closely related to the existing fallow-deer
(C. dama). Cervus Dawkinsii and C. Fitchii are most probably
related to the elk (Alces machlis); C. verticornis, C. tetraceros, and
C. Sedgwickii are all from the Norfolk Forest Bed at Cromer, Bacton,
and Kessingland. C. tetraceros has the beam more or less straight,
with the tines rounded, simple, and springing all from one side
of the beam. C. Sedgwickit has the beam flattened and more —
arched, and the tines, although upon the same plane, are flattened
and branched.
There is yet another extinct deer (the Cervus giganteus), the
largest of all the Cervidee, whose remains have been obtained not
only in great abundance, but in so perfect a state, in Ireland
that entire skeletons are to be seen in many of our Museums, whilst
the antlered skulls adorn many noble residences in England,
Scotland, and Ireland. Formerly known as “ Megaceros Hibernicus ”
or as ‘‘the gigantic Irish elk,” yet it is in no wise related to the
elk, although frequently spoken of as such. It is in every respect
a true deer, and in many of its characters (save that of size) not
unlike our existing fallow-deer.
When it is stated that these deer frequently measure 9 feet
across the antlers, the weight of which is as much as from 80 to
90 1bs., one is astonished at the amount of vital energy in such
a beast as would enable it to throw out year after year such a mass
of osseous matter in the short period of four months, for the horn-
growth of the Megaceros doubtless followed the same rules as those
which govern the horn-growth of other deer to-day.
“In the British Isles this deer seems to have been most numerous
in Ireland, where remains are found below all the peat-bogs in the
lacustrine shell-marl. In County Limerick the greatest number
of heads has been dug up, notably in the extinct Lake of Loch
Gur, where literally hundreds of them have been unearthed. In
1875, Mr. R. J. Moss made excavations in the bog of Ballybethag, —
Y miles south-east of Dublin, and during the summers of 1876-77
twenty-six heads and three complete skeletons were procured.
Below the great bog, in the vicinity of Tullamore, is another
-Reviews—J. G. Millais—British Deer. 135
productive district, as is also the margin of Loch Derg (Co. Galway)
and Killowen (Co. Wexford).
“The first tolerably perfect skeleton of Megaceros was found
in the Isle of Man, and was presented by the Duke of Athole to the
Edinburgh Museum in 1820.”! In 1896 a second, nearly perfect,
example of Megaceros was obtained near Poortown in the same
island. _ (See p. 116.)
In England the remains of this great deer are rare. The first
skull and antlers were dug out of the peat-moss at Crowthorpe in
Yorkshire. About twenty-nine localities are recorded, but the
remains are exceedingly fragmentary. In France its remains are
said to have been found near the foot of the Pyrenees ; in the
valley of the Oise it has been found associated with the mammoth,
the rhinoceros, the musk-ox, the reindeer, and hippopotamus.
There is one skull with imperfect antlers in the British Museum
from as far east as the Government of Orbowschen, in Russia.
Complete heads and antlers have recently been found in the south-
west of Scotland.
There is good evidence for the conclusion that after the great
deer had spread into Ireland, and probably long before its extinction
in this country or in Western Europe, Ireland must have become
isolated from England, and during a long succeeding period
the Cervus giganteus lived and flourished in that island, and
was neither exterminated there by prehistoric man nor by
any of the Carnivora, but by a great and gradual change which
took place in the climate of that country. This change, in
which Scotland and a part at least of England also partook, was
an increase in cold and a settled humidity of climate, tending to
a great growth of peat, which in time filled up the former extensive
fresh-water lakes, once so abundant, and injuriously affected the
forest growth over large areas of the country. With this change
the great Irish deer died out; but its remains show that it was living
there before the growth of Sphagnum or bog-moss had taken place,
for they rest in the shell-marl beneath the peat. This shell-marl is
really composed of the accumulated deposit of dead and decomposed
shells of fresh-water Unio, Anodon, and Limnga, so that it repre-
sents a long and tranquil period of time during which conditions
were favourable to forest growth, and consequently to the deer and
the other denizens of the woods and waters.
We give a diagram-sketch by Mr. Millais of the way the Irish
deer occurs beneath the peat (see Woodcut). The man who searches
for the megaceros-heads uses a rod about 25 feet in length. First of
all he takes a survey of the bog, and from long experience knows
where to commence his probing in what seems a likely spot. Should
the iron strike stone or gravel, he knows by the gritty feel, whilst
horn gives a dull thud, and by turning the rod round and round the
searcher is able to tell of what nature is the substance he has struck.
1 This skeleton from the Isle of Man was described by Baron Cuvier in his
‘« Ossemens Fossiles,’’ tome iv, pl. viii, fig. 1.
136 Poni . G. Millais —British Deer.
How THEY HUNT THE [IRISH DEER AT THE PRESENT DAY.
Showing mode of finding the heads, and the strata in which they are
generally imbedded.
1. Peat (top layers), 3 feet.
2. Gravel, 6 inches.
3. Peat (lower layer with trees), 3 feet.
Layer of oak-leaves, 3 inches.
. Blue clay (mixed with shells), 6 inches. y
Lacustrine shell-marl (with remains of Megaceros, and fresh-water mollusca), 3 feet.
. Blue clay, mixed with subangular stones.
(Thickness shown in diagram, about 12 feet. Many of the peat-bogs are far
thicker.)
Reviews—J. G. Millais—British Deer. 137
Many a time a day’s digging only produces a head not worth lifting,
owing to its being broken in many pieces, or perhaps it is only
a dropped antler.
As to the causes which have led to the extirpation of the larger
mammalia, we do not think it necessary to postulate a universal
cause or agent of destruction before which all the big herbivora
were swept away. Professor Owen long ago pointed out that the
large mammals were always the first to suffer from floods or from
droughts; events which happen most frequently within the tropics,
but which may occur occasionally in almost any country.
Nor can we look at the accumulated-results of subaerial and
diluvial action, especially in such an extensive region as Argentina,
without perceiving that zolian agencies—wind-storms, dust-storms,
rain-storms, and floods—acting on the Sierras and higher plateaux for
thousands of years, have led to the gradual accumulation of those vast
masses of fine material which have built up the great Pampean for-
mation, while along the course of the great alluvial valleys cut through
its deposits by the rivers flowing from the north, lie buried many
hundreds of giant Mylodons, Megatheria, and Glyptodons, once the
denizens of the wooded region of Central South America.
The discovery of thousands of remains of great wingless birds in
the superficial deposits of New Zealand has no connection whatever
with the destruction of giant Edentates in South America, nor with
giant deer in Ireland, save that man the destroyer was for a long
period absent from the scene, and the Dinornis and its kindred
enjoyed for many centuries undisturbed possession of their island-
home, the Harpagornis, a large hawk, being the only bird of prey,
and no Carnivora having reached New Zealand except seals.
With man came the hunter-element (see Plate III), and the
“fire-stick”” ; and the forests, being not unfrequently accidentally
lighted, the affrizghted game (whether deer or Moas) fled towards
the water to escape from the fire, and met their death by drowning
in the morasses they attempted to ford.
In Australia the destruction of the large Marsupialia was probably
not unfrequently caused by drought, which has so often proved fatal
to the flocks and herds of the squatter in our own time. ‘There, too,
also local floods often prove, as in South America, most destructive,
although of short duration, and these may even in a single night
affect a vast area of country.
Mr. Millais has figured many fine antlers of Trish deer, notably
those forming part of the complete skeleton of Cervus giganteus in
Sir Edmund Loder’s Museum at Leonardslee (pp. and 9); and four
heads on p. 19, from Loch Gur, from the Royal Dublin Society,
from County Waterford, and from Limerick, which illustrate
remarkable divergences in mode of growth. The antlers in these
specimens have lost their original crescent-form and become too
much flattened out. This may either have been caused when the
antlers were softened from lying in the bog, or afterwards. when
mounted, they have bent downwards by their own weight. Originally
they were certainly more V-shaped. On pp. 14 and 15 are given
138 Pon peat . G. Millais— British Deer.
two views of a splendid head and antlers from near Tullamore,
Ireland, in the possession of the Duke of Westminster, in which
the palms are enormously developed.
There are remains of 19 individuals in the British Museum,
comprising 4 complete skeletons, 38 antlered males and 1 of a (horn-
less) female; 2 skulls of hinds from Naull, Co. Dublin; 8 skulls
with antlers which have no special locality save “ Later Tertiary
deposits, Ireland”; 1 head from Red Bog, Dunshaughton, Ireland ;
1 skeleton from Axe Corey, Co. Wexford; 2 skulls of males with
shed antlers from the Dogger Bank; and 1 head from Russia.
The remaining types of British Deer—the “Red-deer” (Cervus
elaphus) ; the “ Fallow-deer”’ (Cervus dama); and the “ Roebuck ”
(Capreolus caprea)—are so well known in the living state, that
they would appear to have little claim on the attention of the
paleontologist. When, however, we study the Pleistocene deposits
of our Island, we are led to find that even these denizens of our
parks have a more or less remote geological history, not wholly
devoid of interest.
Taking the red-deer as the typical representative of a great group
of Cervide, which are spread over Kurope, North Atrica, Asia (north
of the Himalayas), and North America, we find these are mainly
characterized by the conformation of the antlers. In this type the.
brow- and bez-tine are both present ; the beam is nearly cylindrical,
subdividing into two or more points at the summit.
The group of allied species would include the red-deer (Cervus
elaphus) ; the Canadian wapiti (C. Canadensis); C. maral; the
Thian-shan deer (C. eustephanus or C. Leudorfi) ; the Amurland deer
(C. wanthopygus) ; C. corsicanus; the Barbary deer(C.barbarus) ; and
possibly also the Hangul or Cashmir deer (C. Kashmirieusis). Our
brickearths, cave-deposits, and peat-bogs also yield evidence of
deer-remains far larger in size than those now living, so that
there can be little doubt that, ancestrally at any rate, the great.
red-deer and the wapiti were closely related.
In Flower & Lydekker’s great work on Mammals, living and
extinct, stress is laid on the absence of a cup at the surroyals,
as distinguishing the wapiti from the red-deer; nevertheless, many
red-deers’ antlers have no trace of the cup whatever. Indeed,
after studying a long series of them one cannot help feeling
that the richly crowned antlers of certain red-deer from the peat,
notably the pair obtained from the bed of the River Boyne at
Drogheda, Ireland (part of the Egerton Collection), owe their
unusual development to specially favourable environments and
abundance of food, as exemplified in the collection of magnificently
crowned heads preserved in the Castle of Moritzburg by H.M. the
King of Saxony (sixty of the choicest of which have been figured
by Dr. A. B. Meyer, Director of the Royal Zoological Museum in
Dresden, in two volumes, royal folio, one vol. published in 1888 ©
and one in 1887).
In Mr. Millais’s work (p. 23) he writes: ‘The Warnham deer are
second to none in this country in the matter of body and horn.
Reviews—J. G. Millais—British Deer. 139
Their origin, however, is quite recent, and even after the introduction
of the Stoke deer, by which the herd was strengthened some years
ago, they were in no wise remarkable until the late Mr. F. M. Lucas
took them in hand and began a series of experiments with a view to
improving the pasture—about 250 acres in extent. Every alternate
year he dressed the land with bone-dust, the effect of which soon
made itself felt. The nutrimental qualities of the grass seemed to
be improved 70 per cent., yielding exactly what was wanted for
fattening and horn-growing. Half the park is reserved for hay,
so the red-deer, which number about 100, have no great extent
of ground to range over and very little winter-feeding. Neverthe-
less, they thrive and have continued to improve steadily since
1884, when the dressing was first tried, and at the present time
a four-vear-old Warnham stag is better than an adult animal in most
other English parks.” (See Pl. IV.)
Mr. Millais gives on p. x an illustration of a pair of antlers
grown by a stag living on an open heather-covered mountain
(Castlewellan, Ireland), with but little wood-shelter at the base.
Two other heads on pp. 1380-1, one from Braemore forest,
Ross-shire, the other from Eskdale, and the pair of fossil antlers
from Bakewell, Derbyshire (figured in Pl. I], Guor. Maa., Feb.
1898), may serve to illustrate the simpler form of red-deer antlers
in which the cup and highly-branched crown are but little
developed; the beam may be of great strength, but it and the
tines are well-formed, symmetrical, and well-adapted for offence and
defence. This type appears to be a mountain-dwelling, hardy,
fighting stag. The crowned antlers with such a large number
of points (often from thirty to forty) are found in the peat-deposits,
and belonged to stags which must have been as well-fed in a natural
state as are those in Mr. Charles Lucas’s park at Warnham Court, or
in the German deer-forest of the King of Saxony at Moritzburg.
Clearly, in these latter instances, the excessive richness of the
growth of antlers is a luxury which would only be found
exceptionally in a wild state, and must require special care for its
proper maintenance even in a park-herd (or under domestication).*
Passing over the fallow-deer as affording less geological interest,
we come lastly to the little roebuck, Capreolus caprea, a small
form of deer and a truly wild denizen of our woods, being found
in Dorsetshire, Hampshire, and Essex, in the south, in the west in
Wales, away north to Scotland, and widely over Europe and
Western Asia. The male is somewhat over 2 feet in height at the
withers, of a dark reddish-brown colour in summer, with a white
patch on the rump. The small antlers stand close together at their
base, have a short rugged beam, rising vertically, then bifurcating,
the posterior branch again dividing. The roe-deer dates from the
1 Mr. Lydekker, F.R.S., informs the writer that there is a magnificent series
of red-deer antlers to be seen in the Hall of Hampton Court Palace, where they
may have been since the days of its founder, the famous Cardinal Wolsey, in 1026, or
since its rebuilding by Wren in 1690.
140 Reports and Proceedings—Geological Society of London.
Pliocene period, and is doubtless related to several other small
Cervide, some of which, like the Chinese water-deer, are hornless
forms.
We must now part with Mr. Millais, but we do so with regret.
We cannot imagine a more charming book for the Library table of
a country house than his “ British Deer and their Horns.”
et Ores AlN» ROC frp sie Ss.
GroLogicaL Soorrry oF Lownpon.
January 19, 1898.—Dr. Henry Hicks, F.R.S., President, in the
Chair. The following communications were read :—
1. “On some Gravels of the Bagshot District.” By Horace W.
Monckton, Hsq., F.L.8., F.G.8.
The author refers to his papers on Gravels South of the Thames
published in the Quart. Journ. Geol. Soc. for 1892 (p. 29) and 18938
(p. 808), and gives some additional details.
He suggests that the occurrence of stones which have been very
little rolled or waterworn in gravels at certain localities affords
evidence of the presence of ice in the water by which those gravels '
were deposited, and that the position of some sarsens which he
describes is due to the same agency.
He gives details and exhibits photographs of a number of sarsens
which he has seen in siti.
2. “On the Occurrence of Chloritoid in Kincardineshire.” By
George Barrow, Esq., F.G.S. (Communicated by permission of the
Director-General of the Geological Survey.)
The rock containing the chloritoid was first found in sitd at the
entrance to the little gully at the head of Friar Glen Burn, near
Drumtochty Castle. It has since been observed at many places
along a belt of country extending from the coast north of Stone-
haven nearly as far as the North Esk.
The rock is easily recognized by the presence of numerous white
spots, which are always present and are larger than the chloritoid.
The chloritoid and the spots vary in size, being largest when
the rock is most crystalline (a schist), and smallest when it is least
crystalline (a slate). The mineral appears as minute glistening
scales in the schist, but in the slate it can be recognized only with
the aid of the microscope.
The optical characters are described, and shown to be identical
with those of the mineral from the Ile de Groix, and with those of
the ottrelite from Ottré and Serpont.
An account of the methods adopted to obtain a pure sample is
given. Several analyses were made, and it was proved that as the
purification increased the analyses approximated more and more
closely to the analysis of the mineral from the fle de Groix.
The final result was as follows :—
Obituary—Professor Dr. Oscar von Fraas. 141
SiO ahs aes acon ah. 26100
AT OS ores ie oe eet ee 0-05)
HeOr fel nas) Cee aL 50
Hes Oth = ah Way Pa ee ane OLD
Mg Ofer ssc) aa eR
Thossonsionition ay ames 6:00
Total Af han oat ees
The author discusses some of the published analyses, and suggests
that many of the discrepancies may be due to impurities in the
material analyzed. :
GIG 5)1544 SISO rN Da aan (Ojash-
THE AGE OF THE RAND BEDS.
Srr,—In the Gronocicat Magazine, 1897, p. 549, Mr. W. Gibson
states that I have obtained fossils of doubtful Carboniferous age from
a dolomite associated with the Gat’s Rand Beds. I am not aware
of having made such a statement, and it certainly does not occur in
the paper alluded to (‘The Occurrence of Dolomite in South Africa,”
Q.J.G.S., vol. t, p. 561). In fact, so far as I am aware, no fossils
of any kind have hitherto been discovered in the Dolomite of this
country. Davip Draper.
JOHANNESBURG, Dec. 31, 1897.
THE OCCURRENCE OF PLACOPARIA IN THE SKIDDAW SLATES.
Str,—In the course of my work on the Graptolite Fauna of the
Skiddaw Slates I have come across two specimens of the trilobite
Placoparia. No mention of this form is made by Postlethwaite and
Goodchild in their paper on the “ Trilobites of the Skiddaw Slates ”
(Proc. Geol. Assoc., vol. ix, p. 455), and as it is known to be
characteristic of a definite horizon in other localities, it seems worth
while to place on record the occurrence of this genus in the Lake
District. The specimens in question come from two different
localities, Outerside and Ellergill, and are in the Woodwardian
Museum. The Ellergill specimen is a recent gift from Professor
H. A. Nicholson. GertruDE L. Ewes.
Woopwarpian Mvuszeum, CamsrinGce, February, 1898.
@aS tere OPA enys=
OSCAR FRIEDRICH VON FRAAS.
Born January 17, 1824. Diep NovEemMBer 22, 1897.
We regret to announce the death of the veteran geologist
Dr. Oscar von Fraas, of Stuttgart, Director of the Royal Wiirtemberg
Museum of Natural History. He was born at Lorch, in Swabia, in
1824, and after his ordinary education at school he proceeded to the
University of Tiibingen. ‘There he devoted special attention to
142 Obituary—Lieut.-Col. C. Cooper- King. .
theology, with the intention of entering the Church; but he was at
the same time also deeply interested in natural science, and he
attended the lectures of Quenstedt, who filled him with enthusiasm
for geology and paleontology. He worked hard in collecting fossils
and making geological observations in Swabia, and when he had the
opportunity of spending a year in Paris, in 1847, he attended the
lectures of D’Orbigny and Elie de Beaumont at the School of Mines.
On returning to his native country, Fraas followed his theological
profession, and from 1850 to 1854 he was pastor of Laufen a. d.
Eyach. In 1854 he became Conservator of the Department of
Mineralogy and Paleontology in the Royal Wurtemberg Museum
at Stuttgart, an office which he held until a few years ago, when, on
the retirement of Dr. von Krauss, he succeeded to the Directorship,
and left his son, Dr. Eberhard Fraas, in charge of the minerals and
fossils. In the course of his official labours, Dr. Oscar von Fraas
not only made the Stuttgart collection one of the finest in Hurope,
and enriched it with Swabian fossil batrachians, reptiles, and —
mammals, many of which are absolutely unique; he also published
popular writings to interest the people in his work, and carried
on a long series of researches, of which the results appear in more
than sixty papers and memoirs. Most of these relate to the geology,
fossils, and prehistoric archeology of Wiirtemberg ; but some also
recount his experiences in the East, which he visited in 1864-6,
and again in 1875. He paid special attention to the geology of the
Lebanon ; and the scientific results of his journeys through Syria
are collected in a small volume entitled ‘“‘ Aus dem Orient,” which
was published in two parts (1867 and 1878). Among his larger
memoirs, those on the Miocene Mammalian Fauna of Steinheim
(1870), and on the armoured reptile Aetosaurus from the Swabian
Trias (1877), are especially important contributions to knowledge.
Dr. Oscar von Fraas was elected a Foreign Correspondent of the
Geological Society of London a few days before his death.
LIEUT.-COLONEL CHARLES COOPER-KING, F.G.S.
Born Frespruary 4, 1843. Dizp January 16, 1898.
CHartes Cooprer-Kine, Lieut.-Colonel Royal Marine Artillery
(retired), died at his residence, Kingsclear, Camberley, Surrey,
on the 16th of January, 1898, aged nearly 55 years. The only
son of Major U. H. King, R.M., Light Infantry, he was born at
Plymouth. He was at school there until the end of 1859, passed
into the Royal Marines as a Marine Cadet in January, 1860, second
on the list, and joined H.M.S. “Excellent.” He passed as a Second
Lieutenant R.M. at the Royal Naval College, Portsmouth, first
on the list (1862); and, recommended for the R.M. Artillery,
he was gazetted at Fort Cumberland. In 1864, he was appointed
to command the detachment of Marines on H.M.S. “Scylla” in the-
China seas and Japan. He was promoted to First Lieutenant in
1865; and rejoined headquarters (Hastney) in 1867. He passed
(fourth) into the Staff College, July, 1868; and in August he
Obituary—Lieut.-Col. C. Cooper- King. 143
married Harriet, daughter of the late C. V. Garrett, of Southsea.
Passing out of the Staff College, first on the list, and specially
recommended, he went through the usual course of study and practice
in regimental duties at Aldershot, and the long course of gunnery at
Woolwich and Shoeburyness (1871). He was appointed Instructor
of ‘actics, Administration, and Law at the Royal Military College
at Sandhurst, 1872; and was Professor of the same subjects
1878-1885. His promotion as Captain dates November, 1875,
and Major by Brevet, 1879. He retired from the Service February,
1886; and devoted his time and energy as a military instructor
or “coach,” preparing subalterns of the ‘Militia for commissions
in the Army. He leaves two daughters and five sons; two of
the latter are Lieutenants in the Army.
After the systematic study of geology and chemistry was
eliminated from the curriculum at the Staff College, and the
professorships thereof had ceased, Colonel C. Cooper- King
succeeded Major Mitchell as Lecturer on Geology in 1886. Dealing
also with such other branches of Natural Science as the officer-
students could find time to study, his synopsis of these lectures
on ‘Applied Science” embraced not only the land, but water
(fresh and salt), air and weather, magnetism and electricity, as well as
food and forage. Colonel Cooper-King drew a large class to geology,
both in the lecture-room and the field; for, being a military expert
himself, his explanations of the science in relation to military tactics
and battlefields were well appreciated.
Whether on the blackboard or on paper, his apt and facile
illustrations of geological conditions and natural-history facts
were very acceptable to his students and his scientific friends.
Always observant, and ready with pen and pencil, his notebooks
were rich with reminiscences of places and people, visited or met
with, at home and abroad. In spite of frequent illness, due to
rheumatism and heart-failure, his energy spurred him to persist
as a hard worker, whether in the study on literary matters, in
the field as military correspondent, or in his class-room among
military students. Many of his friends in the Army remember with
pleasure, and often with gratitude, the advantages they received
from his teaching, as private instructor or at college; and, indeed,
he was always ready to help, both cadet and officer, with advice and
solid information.
He was an Assistant-Hxaminer in Geology, Geography, and
Physiography for the Science and Art Department (South Ken-
sington) and the Civil Service Commission for twenty years.
As literary work, we may notice his books—‘‘On Map and Plan
Drawing,” “ History of Berkshire,” “George Washington,” “The
British Army,” and “The Story of the British Army,” the last-
mentioned lately published. He was Hditor of the “ Great Campaigns
in Europe,” and for some time of “The United Service Magazine.”
Reviews, notices, and miscellaneous pieces by C. Cooper-King are
scattered in different periodicals.
In his ‘‘ History of Berkshire” (HE. Stock, London, 1887), a good
144 Obituary—Lieut.- Col. C. Cooper- King.
knowledge of geology underlies his sketch of the county and
description of the ways and doings, not only of prehistoric man
in the region, but of the many events in historic times during
the conquests and civil wars of Berks. The natural features, which
have had an effect in the development of the county since the
first nomad lived and fished along the banks of the Thames down to
the time in which we live, are carefully considered. We have here
a sketch of the evolution of the county, in its races, its homes,
fortresses, arts of life, domestic and military ; and in its ecclesiastical,
military, municipal, and civic relations.
In this, too, his antiquarian knowledge gave his story vigour
and accuracy. The ancient camps and earthworks were ably
elucidated in the Transactions of the Newbury District Field Club,
of which he was a worthy honorary member.
His clear and succinct account of the Stone Implement Station
in Wishmoor Bottom, near Sandhurst, Blackwater, and Camberley,
with a good plan and an explanation of the structure of the ground,
is published in the Journal of the Anthropological Institute,
vol. 11, No. 6 (January, 1873), pp. 865-872, pls. xx and xxi, Also
noticed in the Brit. Assoc. Report for 1872, Sections p. 190.
Colonel Cooper- King was elected a Fellow of the Geological Society
in 1872. In 1875, he communicated to that Society a paper, written
in conjunction with his friend IT. Rupert Jones, on some newly
exposed sections of the “‘ Woolwich and Reading Beds” at Coley
Hill, Reading, Berks (Quart. Journ. Geol. Soc., vol. xxxi,
pp. 451-457, pl. xxii). The features then exposed were correlated
with those of neighbouring sections described by Buckland and
Rolfe many years ago, and more lately by Prestwich and Whitaker.
Two zones of clay-galls were particularly described, and the beds
and levels from which these balls of clay (and ochreous nodules)
were derived were carefully indicated.
Together with the same friend, Colonel C. Cooper-King had long
studied the conditions and characters of the Bagshot Sands; and
his acute observation and thoughtful conclusions must be regarded
as having given value to the papers on the Bagshot district
published in the Proceedings of the Geologists’ Association,
vol. vi, 1880-81, pp. 319, 429, ete.
His high grade in college work indicated his mental capacity,
strong will, and power of endurance; and his subsequent career
showed his versatility and broad intellectual grasp, also his
determination to use his gifts for the benefit of his country and
especially of those around him.
Thus a man of talent, of great capabilities, of high attainments, —
and enormous energy, conscientiously and willingly exercising his”
powers for the good of others, and working hard for the support
of his family even to the last, has passed away, like a goodly
fruiting tree torn away by the ruthless tide of a flooded river, -
which will distribute the seeds in far-off places, where, like those
previously shed, they must produce good results.
tera a)
THE
GEOLOGICAL MAGAZINE
NEW ObRIES. «DECADE SI Vege VOL. IV:
No IV.—APRIL, 1898.
Ore Garay Arie, AS ana Gases
pent hemi ,
I.—Tue Harttest Grotocica, Mars oF ScoTLAND AND JRELAND.
By Professor J. W. Jupp, C.B., LL.D., F.R.S., V.P.G.S., etc.
fP\HE first geological map of Scotland has a history not less
interesting than that of Smith’s famous map of England;
seeing that what Smith accomplished, single-handed, for the southern
part of Britain, John Macculloch did, with the same independence of
all extraneous aid, for the northern half of the Island. Smith’s fame
has happily been long since vindicated; but, owing to a variety
of circumstances, Macculloch has never received full credit for his
grand work; on the contrary, his fair name and even his veracity
have been too often cruelly aspersed. Macculloch, though of Scotch
descent, was born in the Channel Islands, and patented first in
Cornwall and afterwards as a medical student in Edinburgh. He
was an excellent chemist and mineralogist, and brought to the study
of geological problems an amount of exact scientific knowledge rare
in those who at that day turned their attention to the subject.
Commencing life as an Army-surgeon, he in 1803, when thirty
years of age, was made Chemist to the Board of Ordnance, though
the appointment did not prevent him from practising privately
as a medical man at Blackheath from 1807 to 1811. In the latter
year, however, he gave up medical work and was sent to Scotland
to make inquiries as to the best rock suitable for powder-mills.
Suk sequently, a Commission was formed to ascertain what mountain
in Scotland would prove most suitable for experiments similar
to those carried on by Maskelyne at Schiehallien, to determine
the earth’s density.
In this way Macculloch was led to spend much time in travelling
about Scotland and in studying the rocks of the country, and between
the years 1811 and 1821 he each year devoted portions of every
season to geological work in the North. In 1814 he received the
appointment of “Geologist to the Trigonometrical Survey,” a post
to which it had been proposed, as we have already seen, to appoint
William Smith in 1805.
John Macculloch was an original member of the Geological Society,
and soon became one of the most active workers in it. His paper
entitled “‘ Account of Guernsey and the other Channel Islands ” was
the first which was honoured with a place in the Transactions of
the Society, and many other valuable memoirs from his pen found
DECADE IV.—VOL. ¥.—NO. IY. 10
146 Professor J. W. Judd—Earliest Geological Maps
a place in succeeding volumes. Macculloch was the fourth President
of the Geological Society, occupying the Chair from 1816 to 1818.
In 1819 Macculloch published, in two volumes with an Atlas, his
“Description of the Western Islands of Scotland, ‘including the
Isle of Man, comprising an Account of their Geological Structure,
with Remarks on their Agriculture, Scenery, and Antiquities.”
The maps and sections of this work must be admitted to be: of
extraordinary merit, when the imperfect topographical data at the
author’s disposal are taken into account. His sections, illustrating
the relations of igneous to stratified rocks, are of great value, and
exhibit a very marked advance on anything of the kind that had
ever been produced before.
In 1826 Macculloch, who had collected a vast mass of information
concerning the geology of Scotland, received a commission from the
Lords of the Treasury to construct a geological map of the country.
While he was thus employed, Macculloch received a regular salary
from the Government, and, when the map was completed, it was
engraved and coloured by the order and at the cost of the Treasury.
Macculloch finished the field-work in 1832, and by the middle of
1834 the coloured map was ready for publication, and was, with
accompanying memoirs, sent in to the Treasury.
Unfortunately, however, various circumstances seem to have
delayed the publication of the work. There being no Ordnance
Map of Scotland at the time, Macculloch was compelled to employ
the best private map which then existed—that of Arrowsmith—
on which to insert his geological work. All who have endeavoured
to do any serious geological mapping in Scotland, before the
publication of the Ordnance Map, will sympathize with Macculloch
in his disappointments—frequently verging on despair—in trying
to adequately represent the geological structure of the country on
such an imperfect topographical basis as that of Arrowsmith’s Map.
Macculloch’s Geological Map of Scotland, which has recently been
characterized by a very high authority as “perhaps the most
remarkable achievement of the kind which up to that time had been
accomplished by a single individual,” long remained almost unknown
to and neglected by geologists. In 1851 Murchison referred to
it as being “usually known as Macculloch’s Map,” and as being
“so replete with errata that it would be a waste of time to attempt
to enumerate them.”
Macculloch belonged neither to the school of the Neptunists nor
to that of the Plutonists, and not to take a side in those days of
embittered controversy was in itself almost accounted a crime. In
the accuracy of his mineralogical and petrographical knowledge, |
and in his insistence on the importance of such knowledge to the
field-geologist, he resembled the disciples of Werner; but by the
accuracy of his description of the relation of igneous to sedimentary
masses he did more than any other geologist to confirm and establish
the principles so well shadowed forth by Hutton. When William
Smith’s teaching of the value of fossils in classifying strata had
spread, so as to meet almost universal acceptance among geologists
of Scotland and Ireland. 147
south of the Tweed, Macculloch unfortunately found himself too
old, too conservative, and too opinionated to accept the new views
and to give them the welcome which they deserved.
In spite of omissions and defects, which it would be easy to point
out in any great pioneer work of the kind, Macculloch’s Map is
a splendid production, and all subsequently published maps of the
country have been based upon it. In one important respect the
map, as finally published, did not do justice to Macculloch’s acumen
and research. As is well known, he very early made out the true
relations and age of the Torridon Sandstone and its infraposition
to the Durness Limestone, in which lattér rock he was the first to
detect fossils. Murchison and Sedgwick, however, vehemently
opposed his views, maintaining that the Torridonian was nothing
but Old Red Sandstone faulted down; and, in deference to their
authority, Macculloch allowed his earlier and correct interpretation
to fall into abeyance.
If we seek for the causes of the neglect and injustice with which
John Macculloch’s great work has been so long treated, they are
not difficult to discover. In the first place, Macculloch, excellent
mineralogist and able geologist as he undoubtedly must be admitted
to have proved himself, was a man with many eccentricities of
character—some of them not of the most amiable kind—and he
became extremely unpopular during the later years of his life. In
England, and especially among his earlier associates of the Geological
Society, his contempt, strongly felt and often offensively expressed,
for ‘“‘mere amateurs” could scarcely tend to make his company
agreeable in circles where geology had been so widely cultivated by
unprofessional workers.
In Scotland, a supposed want of patriotism, indicated by a tendency
to point out faults in the national character of the Highlanders,
was a characteristic of Macculloch which made him the subject of
the most rancorous attacks. Hmbittered by this isolation, and
smarting under what he regarded as the undeserved neglect of his
work and the unmerited aspersion of his character, Macculloch in
some of his later works assumed an air almost of omniscience, and
poured unmitigated contempt on all advances in geological science
in which he had not taken a share. Macculloch died as the result
of a carriage accident in Cornwall within a year of the completion
of his map, and when it was only just on the point of being issued
to the public. The earliest copies published bore the imprint
“A Geological Map of Scotland by Dr. MacCulloch, F.R.S., ete., ete.
Published by order of the Lords of the Treasury, by S. Arrowsmith,
Hydrographer to the King”; and one such copy, originally the
property of the late John Phillips, which came into my possession
on the death of that geologist, I have handed over to the Geological
Society, where it is preserved, side by side with the immortal work
of Smith. But the title and description of the map were unfortunately
merely engraved on a loose sheet to be pasted over the title of
the topographical map; and, after the death of Macculloch, this
description was, either by accident or design, usually omitted, and the
148 Prof. Judd—Geological Maps of Scotland and Ireland.
geological map was issued as though it were the work of Arrowsmith.
It must certainly be admitted that Macculloch’s strictures on the
topography of the map were of such a character as to be only too
well calculated to produce resentment in the minds of the publishers.
From this sketch of the history of Macculloch’s Geological Map
of Scotland, it will be seen that the first Government Geological
Survey carried on in the British Islands was that of Macculloch.
It is often said that the work of the Government Survey originated
in the grant of £300 per annum made to De la Beche in 1832
to aid him in his labours in the South-West of England. But as
we have seen, Macculloch was in 1814 appointed Geologist to the
Trigonometrical Survey, and in 1826 was commissioned and paid
by the Treasury to make a regular survey of the country ; and his
map finished before the date of the first grant made to De la Beche
was published at the national expense. ‘his first geological survey
of Scotland by Macculloch has therefore just the same right to
be regarded as a Government Survey as the second survey of the —
country which was commenced in 1854 by the late Sir Andrew
Ramsay, and is now being carried on by many workers with such
admirable skill and energy.
James Nicol’s Geological Map of Scotland—a work of great merit
—which was issued about 1846, bears much the same relation to ~
Macculloch’s map that Greenough’s map does to that of Smith’s.
Nicol’s work could not have been executed had not Macculloch’s—
map been in existence, but the younger geologist was able from his
own investigations, and by collecting and incorporating the work
of many fellow-labourers in the same field, to make his map of
Scotland a much more complete and trustworthy work than the
original of John Macculloch.
The Geological Map of Ireland by Sir Richard Griffith is well
worthy of taking a place side by side with Smith’s England and
Wales and Macculloch’s Scotland. Griffith, who, though born
in Dublin, received his scientific training in London and
Edinburgh, entered the Government service as an Hngineer and
Surveyor in 1809, when only twenty-five years of age. For nearly
fifty years he was constantly employed, travelling in all parts of
the country, examining bogs, mines, and agricultural properties,
carrying on the “ Perambulation or Boundary Survey of the parishes,
baronies, and counties,” and making that assessment of the land so
well known as ‘ Griffith’s Valuation.”
In 1812, when Greenough laid the first draft of his Map of
England and Wales before the Geological Society, he appears to
have pressed upon the attention of his friend Richard Griffith the
desirability of undertaking a similar work in Ireland, and in
the summer of that year the first draft of such a map was made |
by Griffith with the aid of notes supplied by Greenough. This |
draft appears to have been continually added to and improved down |
to the year 1821, when a proposal for its publication was made by
the author in a letter to the Royal Dublin Society. Nothing,
however, came of this proposal; and it was not till 1835, when
Geol, Mag. 1898. 7 | Decade lV, VoLV. PLV.
ahi
ie tO et
G.M.Woodwar d delet hth. West, Newman imp.
alt sgyptian Fichinoidea.
Decade IV. Vol. V.PL VL
Geol. Mag. 189 6.
imp .
Newman
?
West
G.M.Woodward del. et lith.
jan Hcehmoidea.
ligypt
Dr. J. W. Gregory—Egyptian Echinoidea. 149
Griffith was President of the Geological Section of the British
Association at the Dublin Meeting, that he was able to publicly
exhibit in a complete form his Geological Map of Ireland. In the
following year, the Irish Government ordered this map to be
reconstructed and engraved on a scale of one inch to four miles by
the Board of Ordnance. Before the map could be issued, however,
Griffith drew up for the Railway Commissioners a work entitled
an ‘‘Quitline of the Geology of Ireland,” which contained a reduction
of his map, with many of the details omitted. This small map,
which was issued in April, 1838, must be regarded as the first
complete geological map of Ireland that was regularly published.
Ihave not been able to ascertain whether any of Griffith’s earlier
manuscript maps are in existence. In August, 1838, the large
geological map of Ireland appears to have been exhibited at the
British Association Meeting in Newcastle; but it was not regularly
published till March, 1859. A second edition of the map was
published in 1855 by order of the Treasury.
The Wollaston Medal, which was in 1831 awarded to William
Smith for his Geological Map of England and Wales, was in 1854
presented to Sir Richard Griffith for his Geological Map of Ireland.
‘The three pioneer Geological Maps of England, Scotland, and Ireland
have now been placed in juxtaposition in the geological gallery
of the Science Division of the South Kensington Museum, where
they are open to examination and comparison with the earliest
geological maps published in France and other countries. A
study of these maps will serve to demonstrate the priority claimed,
and justly claimed, by Fitton, for the esol maps of this country
over those of any other. part of Europe.
The Geological Map of the Basin of Paris ths Cuvier and Brongniart
was published in 1810, while William Smith’s early maps had
appeared in 1799 and 1801; and the maps of England, Scotland,
and Ireland, by Smith, Macculloch, and Griffith respectively, were
published in 1815, 1835, and 1888, the first complete Geological
Map of France, that of Elie de Beaumont and Dufrenoy, making
its appearance in 1840.
IJ.—A Coturction or Eayrrian Fosstt EcHInoIpea.
By J. W. Grecory, D.Sc., F.G.S.
(PLATES V AND VI.)
\HE first collection of Egyptian fossils sent for determination by
Captain Lyons, R.E., Director of the Egyptian Geological Survey,
to the British Museum, includes an interesting series ae Echinoidea,
which has been intrusted to me for examination. It is hardly
necessary to state that our knowledge of the fossil echinid faunas of
Egypt is mainly due to M. P. de Denis Te Ba who has described
a large series in two admirable BRELOG 2 S88"
1 P. de Loriol, ‘‘ Monographie des Behinides contenus dans les couches nummu-
litiques de Egypte” : Mém. Soc. Phys. Hist. nat. Genéve, vol. xxvii (1881),
pp- 59-148, 11 pls. ‘‘ Kocaene Echinoideen aus Aegypten und der libyschen
Wiiste”: Beitr. Geol. Pal. libysch. Wuiste, Abth. ii, Ht. 1, Palzontogr. Suppl.,
1883, pp. 1-49, 11 pls.
150 ID lls Ve Gregory — Egyptian Echinoidea.
The echinids in the Egyptian Geological Survey Collection include
79 specimens, which are referred to 15 genera and to 30 species, of
which three are new. The horizons are known in each case, but the
localities are not stated for one set, which apparently belong to an
old collection preserved in the Cairo Museum.
The horizons represented are as follows :—
Pleistocene.
Middle Miocene—Helvetian Series: Siuah.
Upper Eocene—Bartonian Series.
Middle Kocene—Mokattam Series.
Lower EHocene—Libyan Series.
Cretaceous—Turonian.
Genus RHABDOCIDARIS, Desor, 1856.
1. Reaspociparis LIBYENs!s, n.sp.
DIAGNosis.
Test large and depressed; width much greater than the height.
The shape is decagonal, with the sides all concave. The ambulacral
areas occupy deep depressions, while the central suture of the inter-
ambulacral areas is also depressed.
Interambulacra.—Each vertical series consists of nine or ten plates.
The tubercles are very prominent, the bases are perforated, and the
mamelons strongly crenulate. The scrobicular areas are not con-
fluent, but separated by one or two lines of granules. The
scrobicular circles are well developed, the granules being much
larger than those covering the rest of the plates. The tubercles
are separated from the ambulacral suture by a series of small
crowded granules, of which there are four or five rows at the
ambitus. The granulated area between the tubercles and the
median interambulacral suture is about twice as wide as on the other
side; it is ornamented at the ambitus by six or seven rows of
granules.
Ambulacral plates.—About eleven correspond to an ambital inter-
ambulacral plate. The pores of each pair are very wide apart, but
are connected by a well-developed groove. The granular area down
the middle of the ambulacrum is wide, and consists of two large
and one or two small granules on each ambulacral plate.
Apical area large, pentagonal.
Dimensions.
mm.
Height of test beh Pes ae ade a xe 30
Diameter of test —... 300 300 500 356 305 54
Diameter of apical system ... Ae 060 300 300 18
Ambulacrum: width of poriferous zone at ambitus ase 2
width of interporiferous zone at ambitus ... 4
Interambulacrum : height of ambital plate 000 B09 7
width of ambital plate 13
width of median granulated area ‘of
interambulacrum at ambitus ... 4
Distripution.— Lower Eocene — Libyan Series: near Assiut;
Coll. Geol. Surv. Egypt, No. 629.
Dr. J. W. Gregory—Egyptian Echinoidea. 151
Ficures. — Pl. V, Fig. la, test from the side; 6, from above.
Fig. lc, two ambital interambulacral plates, x 2 diam. Fig. 1d,
two ambital ambulacral plates, x 4 diam.
AFFINITIES.—This echinid is most nearly allied to Rhabdocidaris
itala (Laube),' which has been described from the Egyptian Hocene
by M. de Loriol-le-Fort. The principal difference between them
is that in #&. itala the tubercles are non-crenulate, whereas in
Rh. Libyensis they are strongly crenulate. The tubercles are also
taller. The shape of the test is more like that of R. Zitteli, Lor.,’
but in that species the granulated areas of the interambulacra are
much more restricted. :
The third echinid with which it must be compared is Porocidaris
Schmideli (Minst.),° with which it agrees in the crenulation of the
tubercles. But the new species has not the slits around the bases
of the mamelons; the interambulacral plates are much taller; in
a British Museum specimen (No. 75,669) of P. Schmideli the height
of the ambital plates is to the width as 9:13; and in P. Schmideli
the epistroma consists of coarser and more uniform granules.
Genus PSPAMMEOCHINUS, L. Agassiz, 1846.
1. Psammecuinus Dvuctet, Wright, 1855.
Synonymy.—See Gregory, “ Maltese Echinoidea”: Trans. Roy. Soc.
Edinb., vol. xxxvi (1891), p. 590.
Disrrisution.—Up. Miocene—Tortonian: Malta. Mid. Miocene—
Helvetian: Egypt; Coll. Geol. Surv. Egypt, No. 822.
There is a broken specimen of a Psammechinus in the collection
which agrees in the characters shown with this well-known Maltese
species. The granulation of an ambital plate of the Hgyptian
specimen is shown on Pl. V, Fig. 3. The species has not pre-
viously been recorded from Hgypt. An allied African species is
P. Soubellensis, Per & Gauth.,* in which, however, one tubercle on
each interambulacral plate is much larger than the rest of the
horizontal series.
2. PsamMecuinus Lyonst, n.sp.
DraGnosts.
Test small; somewhat conical above, with tumid, well-rounded
sides. Base flat. Seen from above the shape is sub-pentagonal,
but with well-rounded angles.
Ambulacra.—Kach ambulacral series consists of about thirteen
plates, each of which bears a single conspicuous tubercle. The
pore pairs are arranged in well-curved triplets. ~ A double series of
miliary granules runs down the middle of each area. The scrobicular
areas of adjacent plates in the same vertical series are confluent.
1 Cidaris itala, G. C. Laube, ‘‘ Ech. vicent. Tert. Geb.’’: Denk. Ak. Wiss.
Wien, vol. xxix, pt. 2 (1869), p. 9, pl. i, fig. 3.
2 De Loriol, 1883, Beitr. libysch. Wiiste, vol. ii, pt. 1, p. 8, pl. i, figs. 1, 11.
3 Oidarites Schmidelii, Minster, in Goldtuss, Petret. Germ., vol.i, p. 120, pl. xl,
fig. 4. De Loriol, 1883, op. cit., p. 9, pl. i, fig. 10.
F 2 pan & Gauthier, Ech. toss. Algér., vol. iii, fase. 10 (1891), p. 252, pl. v,
gs. 1-4.
152 Dio Ve Gregory—Egyptian Echinoidea.
Tnterambulacra of about ten plates in each vertical series. Hach
plate bears a prominent tubercle. The miliary granules are abundant
and well developed. The scrobicular circles are complete, those on
the upper border of one plate completing the circle of the plate
above.
Peristome very large; branchial slits deep.
DIMENSIONS.
mm.
Height of test Ar B58 x8 Ase cae oes 5:5
Diameter Olbestimemese See BG ae 9:5
Width of ambulacrum at ambitus .. ioe ne aes 30
Width of interambulacrum at ambitus ee eas ase D3
Diameter of peristome S06 : tee 4-5
Distripution.— Mid. Misono Sree Gdet Cpe Coll. Geol.
Surv. Egypt, Nos. 977, 988.
Fieurns.—Pl. V, Figs. 4a and 6, a test from the side and from
below, x 2 diam. Fig. 4c, ambital plates, x 8 diam. Fig. 5,
ambital plates of another specimen, x 8 diam.
Arrinitizs.—The species, by its unituberculate, multigranulate
interambulacral plates, belongs to the series of species which Pomel
grouped as the genus Arbacina; while by the deep, narrow branchial
slits it is allied to the same author’s Oligophyma.
Its nearest ally is Psammechinus subrugosus, Pomel, from the
Pliocene of Oran, in which the mamelon of the primary tubercles
is much larger, there are some secondary interambulaeral tubercles,
and the ambital interambulacral plates are longer.
Psammechinus levior, Pomel,” from the same deposits, has a more
scanty epistroma.
The specimen illustrated by Pl. V, Fig. 5, resembles the Arbacina
asperata, Pomel,® from the Pliocene of Gren! but in that form the
tubercles have a much larger, flat mamelon, which is about
two-thirds instead of one-third the diameter of the boss. It also
resembles a small Persian Miocene Psammechinus affinis, Fuchs,* in
which the scrobicular circles are complete on each plate, so that the
adjacent scrobicular areas are separated by two lines of granules
instead of by only one.
Oligophyma cellensis, Pomel,® is another ally, but that has a much
smaller peristome and longer, lower interambulacral plates.
Genus COPTOSOMA, Desor, 1858.
1. Coprosoma Tuevestenss, Per. & G.
Cyphosoma Thevestense, Peron & Gauthier, 1879: ‘‘ Ech. foss. Algér.,”
fasc. vi, p. 105, pl. xiii, figs. 5-8.
DistrisuTion.—Turonian: Tebessa, near Constantine, Algeria. —
Turonian (?) : Abu Roasch, Egypt; Coll. Geol. Surv. Egypt, No. 50.
* Pomel, ‘‘ Pal. Algér.,’’ Zooph., fase. 2, Ech., livr. 1 (1885), pl. C, xii, figs. 1-4.
lipids Dl. C, xii, figs. 5-8. ‘'
SP libide pls Ce xa, fies. 5-8.
2 Fuchs, “Tert. Ech. Persien’”?: Sitz. Ak. Wiss. Wien, vol. Ixxxi, pt. 1 (1880),
p- 99, pl., figs. 6-16. S
o Rommel opscits, ploC. axe micsemle=ge
Dr. J. W. Gregory—Egyptian Echinoidea. 158
Remarxs.—This species is represented by three specimens. The
pores are in ares of five to six pairs in each compound ambulacral
plate. The specimens agree with the Algerian type in all important
respects. The ambulacral plates are unituberculate, and each
tubercle is surrounded by a complete scrobicular circle, so that the
scrobicular areas are not confluent. The tuberculation of an
Kgyptian specimen is shown on Pl. V, Fig. 2.
Genus LAGANUM, Gray, 1825.
1. Lacanum pEpREssvuM, Less.
Synonymy.—See A. Agassiz, “ Revision of Hchini,” pt. i, 1872,
p- 1388.
DisrrisutTion. — Recent: Pacific and Indian Oceans, Red Sea,
Persian Gulf. Pleistocene: HE. Africa; Suez; Coll. Geol. Surv.
Egypt, No. 968.
Remarks.—The collection includes six specimens of a Laganum
from the Pleistocene of the Suez Canal (Coll. Geol. Surv. Egypt,
No. 968). The specimens appear at first sight to differ from the
typical L. depressum, as the margins are tumid, and there is
a depression around the test between the apex and the margin.
This character is described by Professor A. Agassiz in L. Bonani,!
whereas the test of L. depressum is said® to have thin margins. ‘The
shape of the petals in one or two specimens is also different from
the typical L. depressum, as the petals are more pointed at their
outer ends. Hxamination, however, of the large series of L. de-
pressum in the Zoological Department shows that these characters
vary so much in this species that the Egyptian fossils may be safely
referred to it. Some specimens registered as 58. 5. 15. 154, have
equally pointed petals; others from the Kingsmill Islands have the
petals pointed at the ends, but the poriferous zones are broader ;
while in some other specimens the pore-zones are as narrow as in
the fossil specimens from Suez. Among the many varieties of
L. depressum these specimens are most nearly allied to Laganum
attenuatum, L. Ag.,> with which they agree in the circular actinal
depression and the general shape of the test. Some of the six
specimens have the external shape of the variety L. ellipticum, L. Ag.,*
and others have the more strongly pentagonal shape of the typical
L. depressum.°
L. attenuatum is a variety most typical of the Red Sea and
Persian Gulf.
Genus SCUTELLA, Lam., 1816.
1. ScurELLA suBROTUNDA var. Pauuensis, L. Ag.,° 1841.
Remarxs.—This echinid is represented in the collection by two
Miocene specimens (No. 995), of which one is broken. ‘The
1 A. Agassiz, Revision Echini, pt. ili (1873), p. 517.
2 Tbid., p. 518.
3 L. Agassiz and Desor, ‘‘ Cat. Raiss.’’: Ann. Sci. nat., vol. vii (1847), p. 132.
4 L. Agassiz, Mon. Scut., p. 111, pl. xxiii, figs. 13, 14.
® Cf. ibid., pl. xxiii, figs. 1-3.
§ Scutella Paulensis, L. Agassiz, Monogr. Scutelles, 1841, p. 83, pl. xix, figs. 8-10.
154 Dr. J. W. Gregory—Egyptian Echinoidea.
echinids agree with S. subrotunda (non Leske) in the length of the
petals, whereby they differ from the Tongrian S. striatula, Mare.
de Serr. They differ from the typical S. subrotunda, Leske, by the
absence of the notch in the posterior margin of the test behind the
anus. In this character they agree with S. Paulensis, L. Ag.; but
they differ from L. Agassiz’s type of that form by their greater
equality of length and breadth. Agassiz remarked the close
resemblance of S. Paulensis and S. subrotunda ; and it seems to me,
as the shape is inconstant, that the former species should be reduced
to a variety of the latter, characterized by the absence of the notch
and by the less branched actinal furrows. The branching of the
furrows is, however, inconstant; they are not well marked in the
specimens; but in some areas the furrows branch once as in
S. Paulensis, whereas in other areas there are distinct secondary
branches as well.
The original locality of S. Paulensis is St. Paul-trois-Chateaux,
near Dax, and its horizon is Lower Miocene or Langhian.’
Fuchs has described two Egyptian Miocene Scutelle. In S.
rostrata, Fuchs,” from Siuah, the posterior margin is curved and not
truncate; and the interporiferous areas of the petals is broader
than in the two echinids of the Egyptian Survey collection. The
general shape of these specimens agrees with that of S. ammonis,
Fuchs,’ in which the petals are a little shorter; thus, the length of
the anterior petal is 38; of the distance from the inner end of the
petal to the anterior margin of the test, whereas the same proportion
in these specimens is 2.
Genus CONOCLYPEUS, L. Agassiz, 1839.
1. ConoctyrEus Denanovet, De Loriol, 1881.
Mém. Soc. Phys. Hist. nat. Genéve, vol. xxvii, p. 82, pl. ii, fig. 17.
Var. MILVIFORMIS,‘ nov.
Distrieurion. — Libyan Series: Coll. Geol. Surv. Egypt, ex
No. 858. Pl. VI, Fig. 2; two-thirds natural size.
RemaRr&s.—Five specimens in the collection agree in all essential
respects with De Loriol-le-Fort’s C. Delanouei, except that the shape
is not elliptical but somewhat kite-shaped. The greatest width is
a trifle anterior to the peristome; the sides thence run straight
backward, converging slightly till opposite the anterior margin of
the periproct ; thence they bend sharply round to the well-curved
posterior extremity. As De Loriol’s figure (17a) is not regularly
elliptical, and as the test shows a tendency towards this kite-shaped
base, it seems unnecessary to make a new species for these echinids.
But the difference is so constant in the five specimens that it is
desirable to notice it as a varietal character.
* e.g. Depéret, ‘‘ Classification et parallelisme du Systéme Miocéne’’: Bull. Soc.
géol. France, ser. 3, vol. xxi (1893), p. 176. ;
* Fuchs, Beitr. libysch. Wiiste, vol. i (1883), p. 48, pl. xvii, figs. 4-6.
® Fuchs, ibid., p. 48, pl. xiv, figs. 1-4.
* From mzlvus, ‘a kite,’ the test being kite-shaped.
Dr. J. W. Gregory—Egyptian Echinoidea. 155
Genus RHYNCHOPYGUS, D’Orbigny, 1855.
1. Rayncnoryeus Zrrruni, De Loriol, 1883.
“Beitr. libysch. Wiiste,” vol. ii, pt. 1, p. 18, pl. ii, figs. 9-11.
Distripution. — Mokattam Series: Minieh (De Loriol-le-Fort) ;
Coll. Geol. Surv. Egypt, ex Nos. 862, 863.
RemarKs.—The echinid referred to this species differs from the
type only by being slightly broader in proportion to its width.
Genus HCHINOLAMPAS, Gray, 1825.
1. EcHINOLAMPAS TUMIDOPETALUM, n.Sp.
Dracnosts.
Test large and tall, subconical, rising Fae a level base. Seen
from above the shape is sub-elliptical, but the posterior half is
broader and fuller than the anterior part.
Apical area and mouth subcentral.
Ambulacra.—The petaloid portions are very swollen and upraised.
The inequality in the length of the poriferous zones of the antero-
lateral pair of petals is considerable. The petals are long, reaching
nearly to the margins. The poriferous zones are narrow ; the inter-
poriferous area is long, lanceolate.
Floscelle well developed; the bourrelets large and conspicuous.
Dimenstons.
Crushed specimen.
mm. mm.
Height BE ae boc 660 600 48 ahs 49
Length ae ie a0 on 600 78 ae 79
Breadth 600 65 ates 56
Length of petal of antero-lateral ambulacrum 38 sds 35
Width of petal of antero-lateral ambulacrum 11 360 10°5
Width of poriferous zone of ditto... 260 2 ae 2
Width of interporiferous zone of ditto 500 7 Se 6°5
Distance of apex from anterior margin... 38 a 30
Distance of mouth from anterior margin ... 35
Distripurion.—Miocene : Coll. Geol. Surv. Egypt, Nos. 966, 972.
Ficurrs.—Pl. VI, Fig. la, a specimen from above; Fig. 1b, the
same specimen from the side: nat. size.
AFFINITIES.—This species is represented in the collection by
four specimens, of which three are somewhat broken, while the
fourth is a little deformed by lateral pressure. The most striking
character of the species is its swollen ambulacra, which are of the
type met with in Achinolampas stellifera, from the Calcaire Grossier.
From this species H. tumidopetalum differs by its greater size and
more conical test.
Among known species of Zchinolampas this most nearly resembles
EH. Anguille, Cott.,: trom which it differs by the tumid petals and by
the more conical form of the test. The outline seen from above or
below is almost identical with Cotteau’s figures 7 and 8 of his
West Indian species. chinolampas florescens, Pom., var. coarctata,’
1 G. Cotteau, ‘‘Descr. Ech. tert. St. Barth. et Anguilla’’: Handl. k. Svens.
Vet. Akad., vol. xiii, No. 9 (1875), p. 24, pl. iv, figs. 4- 8.
2 A. Pomel, ‘‘ Ech. Kef. Ighoud”’ : Mat. Carte ‘géol. Algérie, ser.i, Pal. (1885),
p- 26, pl. iii, figs. 12-14.
156 Dr. J. W. Gregory—Egyptian Echinoidea.
has a high test of much the same form as E. twmidopetalum; but the
petals are much broader, shorter, and more leaf-like, and the floscelle
less conspicuous.
2, EcHINOLAMPAS GLOBULUS, Laube, 1869.
« Bch. vicent. Tert. Geb. ’?: Denk. Ak. Wiss. Wien, vol. xxix, pt. 2
(1869), p. 24, pl. iv, fig. 5.
Distripution. — Lower Eocene—Libyan Series: near Assiut,
Egypt (De Loriol-le-Fort) ; Coll. Geol. Surv. Egypt, No 6381.
‘'en specimens of this variable species from the Lower Hocene
near Assiut.
8. EcuINOLAMPAS AMYGDALA, Desor, 1847.
Agassiz & Desor, “Cat. Raiss.”: Ann. Sci. nat., Zool., ser. 3,
vol. vii, p. 164.
There is one echinid in the collection (ew Nos. 862-38) the pro-
portions of which agree with those of the Egyptian specimen, which,
according to De Loriol, is the typical form of this species. The
species was based by Desor on an Egyptian fossil. The dimensions
are as follow :—
Coll. Geol. Surv. Egypt. De Loriol-le- Fort.
Length ace So Lp 42 mm. eee 30-38 mm.
Breadth 206 ues ae 20 mm. oy —
Ratio of breadth to length ... “48 sat “00
Height ma hs uae 32 mm. ane =
Ratio of height to length .... “76 ; ofa
Disrripution.—Mokattam Series: Mokattam (De Loriol-le-Fort).
Libyan Series : Coll. Geol. Surv. Egypt, ex Nos. 862-3.
4. Ecutnonampas Prrrireri, De Loriol, 1881.
Mém. Soc. Phys. Hist. nat. Genéve, vol. xxvii, p. 95, pl. v, fig. 2.
Distripution.—Mokattam Series: Mokattam, Thebes (De Loriol-
le-Fort) ; Coll. Geol. Surv. Egypt, ex No. 899.
The collection includes a small specimen from the Mokattam
Series, which appears to be referable to #. Perrieri, Lor., though that
species was described from the Upper Hocene beds of the Siuah
Oasis. M. de Loriol-le-Fort did, however, record a doubtful speci-
men from the Mokattam beds of the Beharieh Oasis.
The dimensions are as follow :—
De Loriol. Egypt. Geol. Surv.,
ex No. 859.
Length eae ae pas 62-62 mm. ... 46 mm.
Breadth ae a cee = 600 ... 3838 mm.
Ratio of breadth to length ... 82) ecw. ae 83
Height des Aap 603 == cto ... 20°5 mm.
Ratio of height to length ... 42-45... 300 “44
o. Ecninonampas Lisycus, De Loriol, 1883.
“ Beitr. libysch. Wiiste,” vol. ii, pt. 1, p. 31, pl. v, figs. 1-3.
Disrrisurion.—Mokattam Series: Siuah (De Loriol-le- Fort); —
Coll. Geol. Surv. Egypt, one specimen ex No. 859.
No. 859 in the Egyptian Survey Collection includes two specimens
which are clearly specifically distinct. The larger specimen has the
Dr. J. W. Gregory—Egyptian Echinoidea. 157
following dimensions, which are those of H. Libycus and £. sub-
cylindricus, Des. But the characters of the petals show that the
Hgyptian Survey specimen is nearer to the former. The specimen
is broken at the posterior end, so the specific determination is
somewhat uncertain.
DIMENSIONS.
Length ats Abe ate ee Bi Sala see 70 mm.
Breadth Bee 5c A a A Ad 55 mm.
Ratio of breadth to length bel ise sige nae es “786
Height yee 900 vs 506 we 35 mm.
Ratio of height to length aul ot ae aa a “50
6. EcHINOLAMPAS AMPLUS, mache 1883.
“Beitr. Kenntn. Miocaenfauna Aegypt.”: Beitr. Geol. Pal. Lib.
Wiiste, vol. i, p. 45, pl. xiv, figs. 5-8.
Distripution. — Miocene: Siuah and Geneffe (Fuchs) ; Coll.
Geol. Surv. Egypt, No. 643; near Wady Jiaffra, between Cairo
and Suez, Camp No. 9.
Genus HUPATAGUS, L. Agassiz, 1847.
1. Evuparagus Corrraur, De Loriol, 1881.
Mém. Soc. Phys. Hist. nat. Genéve, vol. xxvii, p. 139, pl. xi,
figs. 8-10.
Disrrrsution.— Libyan Series: near Thebes (De Loriol-le-Fort) ;
Coll. Geol. Surv. Egypt, ex Nos. 861 and 867.
2. Evpatacus Lisycus, De Loriol, 1883.
“ Beitr. libysch. Wiiste,” vol. ii, pt. 1, p. 52, pl. xi, fig. 4.
Distrigution. — Libyan Series: El Guss Abu Said, west of
Farafrah (De Loriol-le-Fort) ; Coll. Geol. Surv. Egypt, three
specimens ex No. 868.
Genus HYPSOPATAGUS, Pomel, 1885.
1. ? Hyresoparacus LureBvret (De Loriol), 1881.
Macropneustes Lefebvrei, De Loriol, 1881: Mém. Soc. Phys. Hist.
nat. Genéve, vol. xxvii, p. 181, pl. ix, figs. 7-9.
Hypsospatangus Lefebvrei, Cotteau, 1886: Pal. frang. Terr. tert.,
vol. i, Hoe. Hch., p- 96.
Distripution.— Libyan Series: near Assiut, Minieh, and El
Guss Abu Said, west of Farafrah (De Loriol-le-Fort) ; ? Assiut ;
Coll. Geol. Surv. Egypt, ew No. 631.
The only specimen that may belong to this species is one that is
so much broken at the hinder end that it is not possible to’ determine
whether a fasciole was present. The shape of the petals is, however,
nearer to that of Hypsopatugus than to Hupatagus.
2. HypsopaTaGus, sp.
Libyan Series: Coll. Geol. Surv. Egypt, ex Nos. 862-8, 867.
There are two echinids in the collection which are elongate forms
of Hypsopatagus, but they are too ill-preserved for description.
The outline of one is shown on Pl. VI, Fig. 4, which presents
158 Dr. J. W. Gregory—Egyptian Echinoidea.
a considerable resemblance to the Hupatagus Siokutensis, Fuchs,}
which has, however, a more cordate or elliptical test.
Genus HEMIASTER, Desor, 1847.
1. Hemraster ScuweinFurtHt, De Loriol, 1883.
“ Beitr. libysch. Wiiste,” vol. 11, pt. 1, p. 34, pl. viii, figs. 83-5
Distripution. — Libyan Series: El Guss Abu Said, west ‘of
Farafrah (De Loriol-le-Fort) ; Coll. Geol. Surv. Egypt, ex
Nos. 862-3.
PERICOSMUS, L. Ag., 1847.
1. Pericosmus tatus, Ag. & Des., 1847.
Agassiz & Desor., op. cit., p. 19, pl. vi, figs. xvi, 1.
Remarks.—This well-known echinid is represented in the col-
lection by two specimens from the Miocene (Geol. Surv. Coll.
Egypt, No. 964). They agree with Agassiz’s cast (M 28), but differ
slightly from Agassiz & Desor’s figure by the fact that posteriorly
the test slightly overhangs the periproct, which cannot be seen from
above. The specimens agree with Cotteau’s admirable description of
the species ;* and the posterior extremity of the test agrees with his
figure of P. Orbignyi, Cott., to which he applies the same description
as to P. latus. Hence the Egyptian form agrees with Cotteau’s
description better than with the original figure. The echinids differ
from P. Orbigqnyi, Cott., by the greater equality of length and breadth,
the dimensions being 75 mm. and 76 mm. respectively.
2. Pertcosmus Prront, Cott.
G. Cotteau, ‘‘Faune terr. tert. Corse”: Ann. Soc. Agric. Lyons,
ser: 4, vol. ix, 1877, p: 314, pl. xiv, figs. 3,4.
DistrigutTion. — Helvetian: Corsica; Egypt; Coll. Geol. Surv.
Egypt, No. 659.
The collection contains three broken Pericosmi, which have the
anterior apex, steep anterior slope, and long posterior slope
characteristic of P. Peroni, Cott. Two of the three echinids are
too broken for satisfactory determination, but a third shows the form
of P. Peroni fairly well.
Genus LINTHIA, Merian, 1858.
1. Linrata Ascuersont, De Loriol, 1883.
“ Beitr. libysch. Wiste,” vol. ii, pt. 1, p. 37, pl. ix, figs. 1-4.
Disrrreurion.—Libyan Series: Gebel Ter, near Esneh, and west
of Farafrah (De Loriol-le-Fort) ; Coll. Geol. Surv. Egypt, ex
Nos. 862-3.
2. Linrata HsnrHensis—ASCHERSONI.
Linthia Esnehensis, De Loriol, 1883 : “ Beitr. libysch. Wiiste,” vol. ii,
pt. Lp: 39) ppl ix, digs. o,/0:
L. Aschersoni, De Loriol, 1883: ibid., p. 87, pl. ix, figs. 1-4.
1 Fuchs, ‘‘ Tert. Kch. Persien’’: Sitz. Ak. Wiss. Wien, vol. lxxxi, pt. 1 (1880),
p- 100, pl., figs. 17-20.
> G. Cotteau, ‘‘ Faune terr. tert. Corse’’?: Ann. Soc. Agric. Lyons, ser. 4, vol. ix,
pp- 310-12.
Dr. J. W. Gregory—Egyptian Echinoidea. 159
There is in the collection a specimen which is intermediate
between the above, but nearer, if anything, to L. Hsnehensis. The
relative dimensions are as follows :—
Esnehensis. -Aschersoni. Egypt. Sury. Coll.
Length ... .. 80-42 mm. 26-37 mm. 36 mm.
Ratio of breadth to leneth 1-110 ... I see anaaluele4
Ratio of height to length PUB) ooo 8) = OY a0 “74
But the Egyptian Survey specimen has the shallow anteal notch
and broader anterior ambulacrum of L. Aschersoni; the ridge of the
posterior interradius is higher than in L. Aschersoni, but lower than
in L. Hsnehensis. ‘The apical disc of this echinid is shown on PI. VI,
Fig. 3.
Distripution.— L. Bixoctaenst, Lor., Libyan at Gebel Ter, near
Hsneh (De Loriol-le-Fort). L. Aselvansant, Lor., Libyan at Gebel
Ter, near Esneh, and west of Farafrah.
The above-mentioned Egyptian fossil is from the Libyan Series
(De Loriol-le-Fort), ex Nos. 864-5.
3. LINTHIA CAVERNOSA, De Loriol, 1881.
_ Mém. Soc. Phys. Hist. nat. Genéve, vol. xxvii, p. 111, pl. viii,
fies. 8-10.
Disrrisution.— Libyan Series: Gebel Omm-el-Renneiem; Hl
Aouhi, near Edfou ; Djebel Fatira (De Loriol-le-Fort) ; Coll. Geol.
Surv. Heypt, ex No. 867.
4. Linrata Denanovst, De Loriol, 1881.
Mém. Soc. Phys. Hist. nat. Genéve, vol. xxvii, p. 109, pl. vii, fig. 12.
Distrrpution.—Mokattam Series: Mokattam (De Loriol-le-Fort).
Libyan Series: Gebel Ter, near Hsneh (De Loriol-le-Fort) ;
Coll. Geol. Surv. Egypt, ex No. 996.
The collection includes one large, well-preserved specimen of this
species. Its dimensions are:
mm.
Length 600 06 300 00 bas bce boc 60
Breadth du 366 bag ae eA as 000 575
Height 500 se sus 45
Distance of apical system from anterior margin se 609 20
5. Lryrura (?) Correaur, Tournouer, 1870.
SyNoNyYMyY.
Periaster Cotteaut, Tournouer, 1870, “ Ech. calc. & aster. sud-ouest
France”: Actes Soc. linn. Bord., vol. xxvii, p. 33,
Dleexvilh foe:
Linthia Cotteaui, Cotteau, 1886: “Pal. frang. Terr. tert.,” vol. i,
Gib, Oe Aésll5 (oll, Woot
Distrisution.—Mid. Hocene: Hastingues, Landes (Tournouer &
Cotteau). Libyan Series: Egypt; Coll. Geol. Surv. Egypt, ex
No. 868.
Remarks.—The generic position of this species seems to me
doubtful. The dimensions of the specimen assigned to it are as
follow :—
160 DrNIW: Gregory—Egyptian Echinoidea.
Length eae écc 235 bon boo ei ase 37 mm.
Breadth 500 300 956 ode 680 35 mm.
Ratio of breadth to length bod ie sh a ue “95
Height one soc oo 200 300 27°5 mm.
Ratio of height to length ae 3c 306 o00 ies
Apical disc : * distance from anterior margin 17 mm.
Apical dise : ratio of distance from anterior margin to length “46
The specimen shows hoth peripetalous and lateral fascioles. The
dimensions show that the apical disc is anterior in position, and
hence the fossil is a Linthia. The echinid has, however, the very
short posterior ambulacral petals, while the petals of the anterior
pair are longer and more flexuous. The petals, moreover, are deep.
These characters are unusual in Linthia, but are very frequent in
Schizaster. Hence the species has more the characters of a Schizaster
with an anterior apical disc than of a normal Linthia. Cotteau,
indeed, remarks (op. cit., p. 243) that the French specimens have
the apical disc either central or even slightly posterior ; so that he
was doubtful as to the generic position of the species.
The nearest allied echinid previously recorded from Hgypt is the
Linthia Arizensis (D’Arch.), which is, however, much flatter and
more depressed.
As there is only one specimen of this form, its specific determination
is necessarily somewhat uncertain.
Genus SCHIZASTER, L. Agassiz, 1847.
1. Scuizaster Tuesensts, De Loriol, 1881.
Mém. Soc. Phys. Hist. nat. Genéve, vol. xxvii, p. 125, pl. ix,
figs. 5-6.
Disrrisution. — Libyan Series: Todtenberg, near Assiut (De
Loriol-le-Fort) ; Coll. Geol. Surv. Egypt, ex No. 868.
2. ScuizaAsteR Moxarramensis, De Loriol, 1883.
“ Beitr. libysch. Wiiste,” vol. ii, pt. 1, p. 41, pl. x, figs. 1, 2.
Distrisution. —- Mokattam Series: Mokattam (De Loriol-le-
Fort). Libyan Series: Gebel Ter, near Hsneh (De Loriol-le-Fort) ;
Geol. Surv. Egypt, ex No. 867.
3. SCHIZASTER ZitTei, De Loriol, 1881.
Mém. Soc. Phys. Hist. nat. Genéve, vol. xxvii, p. 122, pl. ix, fig. 2.
There are one good and three crushed specimens of this species in
Nos. 864-5.
Disrrisution.—Mokattam Series: Mokattam (De Loriol-le-Fort).
Libyan Series: Coll. Geol. Surv. Egypt, ex Nos. 864-5 ; Gebel Ter,
near Hsneh (De Loriol-le- Fort).
4, Scuizaster Gavpryi, De Loriol, 1881.
Mém. Soc. Phys. Hist. nat. Genéve, vol. xxvii, p. 120, pl. ix, fig. 1.
DistriputTion.—Mokattam Series: near Thebes; Mokattam (De —
Loriol-le-Fort). Libyan Series: Coll. Geol. Surv. Egypt, No. 996.
The collection includes two specimens of this species. The two
specimens differ in the size of the anterior ambulacral depression ;
A. J. Jukes-Browne—The Vale of Marshwood. 161
in one of them the ambulacral furrow is considerably larger than in
the other. It seems unnecessary to regard this as a specific or
varietal difference, for it may be either sexual or a seasonal variation,
the anterior furrow being enlarged to serve as a marsupium.
EXPLANATION OF PLATE V.
Fies. la and 16. Rhabdocidaris Libyensis, nov. sp., from the side and from above ;
nat. size. Fig. le, ambital interambulacral plates of the same, x 2 diam.
Fig. 1d, ambital ambulacral plates of the same, x 4 diam.
Fig. 2. Coptosoma Thevestense, Per. & G., ambital plates, x 4 diam. Turonian:
Abu Roasch.
Fic. 3. Psammechinus Duciez, Wright, ambital plates ef Egyptian specimen, x 5 diam.
Fies. 4 and 5. Psammechinus Lyonsi, nov. sp. Fig. 4a, side view, x 2 diam. ;
Fig. 46, actinal view, x 2 diam.; Fig. 4c, ambital plates, x 8diam. Fie. 5.
Ambital interambulacral plates of another specimen, x 8 diam.
EXPLANATION OF PLATE VI.
Fies. la and 16. Echinolampas tumidopetalwm, nov. sp., abactinal and lateral views ;
nat. size.
Fie. 2. Conoclypeus Delanouei, Lor., var. milviformis, nov., actinal surface; two-
thirds nat. size.
Fie. 3. Linthia Esnehensis —Aschersoni, apical disc, x 5 diam.
Fic. 4. Hypsopatagus, sp., side view; nat. size.
IJ].—Tue Oricgin or tHe VALE or Marsnwoop 1n West Dorset.!
By A. J. Juxrs-Brownz, B.A., F.G.S.
T\HE great sheet of Chalk which, with the subjacent Greensand
and Gault, stretches through so large a part of Southern
England and underlies the whole of the Hampshire Basin, termi-
nates abruptly in West Dorset. There is no doubt that the Upper
Cretaceous rocks once spread continuously over the Jurassic hills
east of Bridport and across the Vale of Marshwood, and were united
to the corresponding beds in East Devon, where the Chalk and
Greensand are so conspicuous in the cliffs near Beer Head.
To those who are unacquainted with geological methods this
statement may seem highly imaginative, since, at the present time,
there is a broad intervening tract, from the centre of which all
traces of Cretaceous strata have been removed, and around which
only a few isolated patches or outliers of Greensand remain as relics
of their former extension; yet to the eye of a geologist these very
outliers, of which Pilsdon Pen is one, are clear and certain proofs
that a continuous sheet of the same material once overspread the
whole area.
The physical features of this area may be briefly described, as they
are not likely to be familiar to those who do not live in the west of
Dorset. The Vale of Marshwood is an area of low ground, most
of which lies between 100 and 200 feet above the sea; its length is
about five miles and its breadth three; its floor consists of the
clays of the Lower and Middle Lias, and it is encircled by steep
1 This paper is reprinted, with some alterations, from the Proceedings of the
Dorset Nat. Hist. and Ant. Field Club, vol. xviii, and is published with the
permission of the Director-General of the Geological Survey of Great Britain.
DECADE IV.—VOL. V.—NO. IV. 11
162 A. J. Jukes-Browne—The Vale of Marshwood.
slopes formed by the yellow micaceous sands of the Marlstone
Beds, the cincture of the hills being only broken on the south by
the gaps through which the rivers Char and Simene escape to the
sea and by a dry gap or pass above Chideock.
The hills on the north side of the Vale are higher than those on
the south side, and they form the watershed dividing the valley
of the Axe from the valley of the Char, which occupies the greater
part of Marshwood Vale. Pilsdon Pen and Lewesdon Hill are
the highest hills in Dorset, Pilsdon being 907 feet and Lewesdon
894 feet, according to the latest Ordnance Survey Map. It is only
on the Blackdown Hills in Devon that the Upper Greensand reaches
a greater height than this, and these hills, although so much farther
west, do not attain to more than 930 feet.
It is obvious, therefore, that there must be some local reason for
the great height to which the Greensand reaches in Dorset, and
yet I am not aware that any geologist has accounted for the fact.
It may seem a paradox to say that the height of the Greensand
hills and great hollow of the Vale of Marshwood are due to one
and the same cause, yet it is true that they are so closely related
to one another that the history of the one involves the history of
the other. This history begins with the uplift of the strata which
took place in Miocene or Pliocene times, and bent the beds into ©
a dome-shaped elevation, or pericline, i.e., an area in which the
strata are bent up so as to dip outwards in all directions from
a central spot or axis.
I propose to ascertain the probable whereabouts of this centre
by a consideration of the levels through which the base of the
Upper Greensand passes in Hast Devon and West Dorset. It
might be thought that this spot could be found more easily by
examining the arrangement of the Jurassic rocks on the borders of
the Vale of Marshwood, but though these undoubtedly show the
existence of an anticlinal axis running in an east-and-west direction
from which the strata slope to north and south, the curve to east
and west is not so apparent in them because they had received
a decided easterly tilt before the Greensand was deposited on them.
Moreover, the Jurassic rocks are broken by many faults, and only
a few of these affect the Cretaceous strata, for most of them seem
to date from the Purbeck and Wealden periods, when the above-
mentioned tilting was produced.
It is therefore by the position and relative heights attained by
the base-line of the Gault and Greensand that the periclinal uplitt
of this district can best be determined, and by transferring the
boundary-lines from the published Geological Survey map to the
six-inch county maps, we can easily trace the rise and fall of this
base-line. The boundary-lines on the old Geological Survey map
are not everywhere correct, but I have good reason to believe that
this particular boundary is sufficiently accurate for our purpose. _
The map (Fig. 1) is based on the new one-inch Ordnance map, and
the geological lines have been partially revised, so that it is more
accurate than the old Geological Survey map.
Fic. 1.—GzotocetcaAn Map or A Portion or West Dorset.
Scale half an inch to a mile.
Clays of Mid.and Lower Lias (ig) FOUL gem
o iN dy! Kil Sil
II Ii)
. il
: my Fa
| yee
if ech
ui iE | i
8 =f Hy il!
| IN =I Pil
Nie ith SOLS i
2 {Il x
ee eT] ! :
i ee
WMH | |
N sant
| i ——on
|
es
Ih i RS
|
i : iy
Chalk =a Upper Greensand ee Lower Ootite “WH Up. Liasand Marlstone Sand
mr
|
ll paws
Wee? = en
EUMUMAH aa
(ey ml ; ee (|
(li — Hii im
ante Sear. iW" '
7S ce THD J Ki
Be iN ee Sat
AN i eee ea |
AA lls K—82— fro a
eA B= =
164 A. J. Jukes-Browne—The Vale of Marshwood.
Commencing with a traverse from west to east through Pilsdon
and Lewesdon, and starting the base-line of the Greensand at
Secktor, near Axminster, we find it there to be only about 320 feet |
above sea-level, and thence it rises gradually eastward till it reaches
580 feet at Birdsmoor Gate, 700 feet at the southern end of Pilsdon,
and about 770 feet on Lewesdon. Between Lewesdon and Beaminster
there are several faults breaking the Jurassic rocks, but it is not
certain that any of them displace the Cretaceous series, and on
Hackthorn Hill the base of the Greensand is close to the 500 feet
contour. The distance from Lewesdon to this point is four miles,
and, assuming the fall to be gradual, it is a little, but not much
more, rapid than the rise from the west up to Lewesdon.
Taking next a traverse through the southern outliers near the
coast, we find the Cretaceous base-line in Black Ven Cliff at about
320 feet above the sea. Thence it rises to about 350 feet in Stone
Barrow, and 400 and more on Golden Cap and Langdon Hill, and
finally to about 500 feet on Hype Down. Then comes a space of
four miles occupied by low ground near Bridport, and when Green-
sand is next found on Shipton Hill, its base has fallen to 400 feet,
sinking still lower eastward to 300 feet at Askerswell. Along this
line of country, then, as along the first, we seem to have a gradual
rise and fall in the height of the Cretaceous base-line.
We will next trace the rise and fall of the same line from north
to south. This is best shown on the western side of the area.
North of Thorncombe village the base of the Greensand lies at about
450 feet, on the south side of that outlier in the same latitude it is
nearly 500, by Lambert’s Castle it is about 600 feet; thence it falls
to 550 feet below Coney’s Castle and to 350 feet at Stonebarrow,
24 miles further south.
_ On the eastern side of the district the regularity of the rise is
broken. by faults, but we find it rising to a maximum of 600 feet
on Drakenorth Hill, east of Poorton, falling thence rapidly both to
the north and to the south. Hven where it is faulted up again on
Eeggardon Hill it does not seem to get much above 400 feet, and at
Combe, near Litton Cheney, it is down to about 500 feet.
We may fairly assume that the centre of the uplift, or pericline,
will be found by drawing lines between the points where the base-
line reaches its greatest height, namely, from Lambert’s Castle to
Drakenorth Hill, and from Lewesdon to Eype Down. The inter-
section of these lines occurs a little east of Monkswood, above the low
ridge which forms the watershed between the Char and the head
branch of the Simene brook. We may take this spot as the
approximate centre of the pericline, which appears to have an ~
elliptical shape, its longest axis being from east to west and its
shortest from north to south. We can even form a good estimate
of the height to which the base of the Greensand reached over this —
centre by prolonging the actual rise of the base-line in the Pilsdon
outlier, for at the north end of Blackdown, by Stony Knap, it is at
500 feet, rising thence to 700 feet below the Pen, and if this rise
were continued south-eastward to the spot above mentioned it would
A. J. Jukes-Browne—The Vale of Marshwood. 165
bring the base to a height of 877 feet. Assuming the thickness of
the Cireemeama there oD have been 180 feet, the Chalk would have
come in at about 1,150 feet.
The relative levels of sea and land varied, of course, at different
epochs of Tertiary time, but we are quite warranted in believing
that there was a time when the Chalk and Greensand formed a con-
tinuous mantle over the rocks which now occur in West Dorset.
Let us next consider how this mantle of Cretaceous material has
been so largely removed from the district in question.
When the country was raised above the level of the sea at the
close of the Oligocene period it must have undergone considerable
erosion from he. planing action of the sea waves, and if the flexures
were commenced at that time the anticlines would suffer most. We
know very little about the history of this part of England during the
Miocene and Pliocene times, but the final result of. the successive
upheavals and denudations was to leave a surface of erosion which
was planed across the flexures, and both upheaval and denudation
had been carried on to such an extent that the Chalk had been
either entirely or almost entirely removed from the central parts of
the anticlinal areas.
This surface of erosion was what our American cousins call
a peneplain, that is to say, it was not a level plain or plateau, but
had its slight irregularities and slopes, and had, moreover, a summit
elevation from which it sloped in more than one direction. A con-
sideration of the present watersheds and of the river-courses in
Dorset and the adjacent counties leads us to infer that the original
watershed of this peneplain lay to the north and west of the line
now occupied by the Chalk escarpment.! It probably trended from
somewhere in the neighbourhood of Wincanton at a high level above
Sherborne and Yetminster to Beaminster Down, and thence over
Lewesdon and Pilsdon to the hills between Axminster and Lyme.
The western part of this line, from Beaminster Down along the
ridge on which Lewesdon and Pilsdon stand, is still the watershed
between the streams which run southward and those which drain
into the rivers Parret and Axe.
It will be noticed that this watershed does not coincide with the
longer axis of the Marshwood pericline, but lies to the north of it.
In order, therefore, to understand the drainage system of this part
of Dorset we must imagine a time when the surface of the land
sloped gently both northward and southward from the line above-
mentioned. On this surface there was a certain accumulation of
clay, pebbles, cherts, and flints, the heavy and insoluble relics of the
Hocene, Greensand, and Chalk which had been destroyed ; remnants
of this deposit, which is generally called “the clay with flints,”
still remain on the tops of the higher hills.
The rain flowing down the southern slope of this surface gathered
into streams, which cut channels for themselves through the Chalk
1 See ‘‘ Origin of the Valleys of North Dorset,”’ in Proc. Dorset N.H. and A.F.
Club, vol. xvi, p. 5
166
A. J. Jukes-Browne—The Vale of Marshwood.
and Greensand. They ran, of course, high above the present surface,
and their courses were prolonged far to the southward before reaching
the sea ; indeed, during the Miocene and again in the later Pliocene
time it is probable that most of the English Channel was dry
Golder:
Cap
‘Hardown
ill
677
t
1
E ros v2 On
:- 2
Pen
850°
LLL
ZL
Pilsdon
ildhay
Ch
aT
i RI
Fia. 2.—Section across the Vale of Marshwood along the broken line on the Map.
Pay aa a tit
land, and that these Dorset streams were merely
tributaries of a large river which ran westward
down the valley of the Channel.
Now the slope along which these streams made
their way was planed across the summit of the
low dome or pericline, which has been described ;
and as we have calculated the base of the Green-
sand on this summit to have been about 100 feet
higher than it is at Lewesdon, where the thickness
of Greensand at present is not more than 180 feet,
and as the surface sloped southwards from Lewes-
don, there cannot have been much Greensand left
over the central area of the pericline when the
streams began to make their valleys. Hence, as
they deepened their channels they would quickly
cut through the Greensand on the central area
and would soon enter the Jurassic beds on which
the sand rests; these beds are the Midford Sand,
the Upper Lias clay (which is thin), and the »
Marlstone Sands.
As soon as any stream cut into the Upper Lias
the water on the overlying sands would issue in
the form of springs. Thereby the volume of the
streams would be increased and at the same time
Jandslips would take place, as is always the case
where springs issue from sand overlying a clay.
The valleys would be rapidly widened, and during
periods of upheaval they would be deepened also.
Much of this work was probably done during the
Glacial Period, and was finally completed during
the time when the raised beaches of the South
Coast were being elevated to their present height.
Over the western part of the pericline the Midford
Sands and Upper Lias are absent; that is to say,
they were planed off before the Greensand was
deposited, and the latter rests directly on the
Marlstone Sands. Here the process of valley
erosion would continue till the base of these
sands was reached, when strong springs would
be thrown out by the underlying margaritatus
clays, and these clays would be for a certain
distance exposed along the valley bottoms.
We must remember that all this time the slope
of the valley-ways was less than the southerly —
inclination of the beds on the southern curve of
the pericline; hence the rivers, after cutting
A. J. Jukes-Browne—The Vale of Marshiwood. 167
through the lower clays for a space, would again enter the Marlstone
Sand and still further south would again enter the Upper Lias and
Midford Sand, as shown in the diagram (Fig. 2).
Now, where the sides of a valley consist of clay, they are rapidly
acted on by rain and frost and are made to recede by frequent
landslips, but where they consist of firm and dry sand there is very
little slipping and the valleys remain comparatively narrow. ‘Thus
it came to pass that a wide tract of clay was gradually exposed over
the western part of the periclinal area, while to the southward the
rivers pass through valleys with steep slopes on each side, the inter-
vening tracts rising into a succession of hills, some of which are
capped by patches of Inferior Oolite and others by remnants of the
original covering of Greensand.
These southern hills are well seen by anyone standing at the foot
of Pilsdon Pen, and they look as if they would present an impassable
barrier to any river running southward from the watershed on which
the observer stands.
The rivers which now drain the district are the Char and the
Simene, while the Brit drains the eastern part of the periclinal area,
and they all make their way through gaps in the southern hills.
But, besides the valleys of these rivers, there is a wide gap at the
head of the valley of the little river Chid, which runs through
Chideock, and I think it probable that this gap was part of the
valley of a river which had a more northern source. There is little
doubt that in some cases one river-system extended itself at the
expense of another, the lateral tributaries of the one encroaching on
the area drained by the other, and sometimes entirely cutting off or
capturing the headwaters of the adjacent river.’
The present course of the Char is so different from the com-
paratively straight courses of the Simene and the Brit, that it
suggests the idea of its having absorbed the tributaries of an eastern
neighbour. The col at the present head of the Chideock valley does
not rise above 250 feet, the hills on each side being double that
height, and I am inclined to think that there was a time, before the
valleys were carved out to their present depth, when three rivers
traversed the Vale of Marshwood, and that the ancestor of the Chid
was one of them. The final sculpturing of the country took place
during and soon after the close of the Glacial Period, and it was
probably then that the capture by the Char of the upper tributaries
of the Chid was accomplished.
In conclusion, I may briefly call attention to the points of
resemblance and difference between the Vale of Marshwood and
the Weald of South-Eastern England. Both are elliptical periclinal
areas, both have been truncated by planes of (presumably marine)
erosion, and both have rivers, which, after traversing the inner plain,
pass through gaps in the southern escarpment to reach the sea. In
the Weald, however, the watershed coincides roughly with the longer
1 For a case in Lincolnshire described by the author, see Quart. Journ. Geol. Soc.,
vol. xxxix, p. 596, 1883.
168 A. J. Jukes-Browne—The Vale of Marshwood.
axis of the pericline, and the streams run both northward and south-
ward, so that both lines of escarpment are trenched by river-valleys.
In the case of the Dorsetshire Weald the original watershed was
outside and north of the central axis, so that all the streams ran
southward and only the southern border is trenched by river-valleys.
In both areas, too, the denudation of the central region has laid
bare a large tract of clay, and on this clay-soil fine forests of oak-
trees came into existence. The great forests of the Weald were
famous for their oaks, which in former days contributed largely to
the ‘wooden walls of England.” In the western country the Vale
of Marshwood was equally celebrated for its oak-trees, and when
ships were largely built in the South of England they were much in
demand. Many hundreds of fine oak trunks have been taken from
the Vale and shipped from Lyme and Bridport. The trade indeed
has not entirely ceased, and such cargoes are still embarked at the
small port of West Bay, below Bridport; few, however, now come
from the Vale of Marshwood, for its woods have disappeared, and
the only oaks that remain are hedgerow-trees.
With respect to the isolation of Pilsdon and Lewesdon Hills,
this has been effected by the excavation of the intervening spaces ;
in technical language they are “hills of cireum-denudation.” The
interspaces are the heads of the valleys formed by the action of rain
and springs on the slopes of the old watershed. The tributaries of |
the Axe have trenched it on the north, while on the south side the
strong springs thrown out at the base of the Marlstone Sands have
eaten backward some little way into the ridge of the original water-
shed, causing the actual water-parting to retreat northward. This
recession has taken place principally near the villages of Pilsdon
and Bettiscombe, while Lewesdon may really be very nearly on the
site of the original ridge of the watershed.
The same process has taken place near Beaminster, where the
spring-heads which furnish the headwaters of the Brit have un-
doubtedly eaten deep into the Chalk and Greensand area, and there
the escarpment is still receding, as the frequent scars of landslips
testify.
It will be seen, therefore, that the history of the evolution of the
present physical features of West Dorset involves the consideration
of many agencies and many conditional phases. Here, as elsewhere,
rain, rivers, snow, frost, and heat have been the principal agents at
work, but in order to understand how their operation has resulted in
the particular arrangement of hills and valleys which we see around
us, we must form some conception of the conditions under which —
they started to work, and we must remember that their working
powers have always been guided and modified by the changes in the |
relative height of sea and land, those slow movements of upheaval
and subsicence to which every portion of the earth’s crust has been
repeatedly subjected.
Rev. J. F. Blake—The Llanberis Unconformity. 169
TV.—A Revinpication or tHe Luanserts UnconrorMity.
By the Rev. J. F. Buaxz, M.A., F.G.S.!
Preliminary Remarks.
IG a paper published in the Quarterly Journal of the Geological
Society for 1893,? I gave an account of the evidence that led
me to conclude that certain conglomerates and associated rocks
occurring for some distance north-east and south-west of Llanberis,
which had hitherto been considered to lie below the workable
Cambrian Slates of that area, were in reality unconformable deposits
of a later date than those slates. In the year 1894 Professor
T. G. Bonney and Miss C. Raisin published in the same Journal®
a controversial paper criticizing my statements and conclusions.
It may seem rather late in the day to be replying to a criticism
made so long ago, and reasons for the apparent delay must therefore
be given. At the reading of their paper before the Society
I welcomed it as an attempt to examine the district I had described,
and it was only on reading it in full that I realized its true
character. I was then just leaving for India, and though a large
part of the criticisms might have been replied to at once, there
were statements in it which could only be explained and accounted
for after another visit to the ground, and this I was unable to
make till my return, when I at once presented my reply to the
Seciety—their Journal being, in my opinion, the proper place for it
to appear in. As the Council, however, are of a different opinion,
such part of my reply as refers especially to the criticisms on my
work is here presented in a modified form with additional remarks.
There was nothing in that paper which in any way suggested
to my own mind that I might be wrong, but I can well understand
that anyone reading it might believe that my conclusions were so
ill-founded that a short visit to the district by another observer might
suffice to upset them. My object, therefore, here is to show that
it is not I but my critics who are in error.
The question whether a certain conglomerate in North-West
Carnarvonshire is conformable or not to the underlying rocks may
seem at first sight to be of no great consequence, but it involves the
larger question. as to where the base of the Cambrian system is to be
drawn—that is to say, what beds are to be included in or excluded
from the Pre-Cambrian series; and this is a matter in which some
of the foremost of present and past geologists have interested
themselves.
This being the case it is probably unnecessary here to point out
the bearings of the several factors involved. It will suffice to note
what views of the subject have been taken by different observers,
in order to show how far my own views or those of my opponents
coincide with or differ from those of others.
1 The substance of a paper read to the Geological Society on December Ist, 1897,
with additional remarks.
2 Vol. xlix, pp. 441-446.
3 Vol. L, pp. 578-602.
170 Rev. J. F. Blake—The Llanberis Unconformity.
History of Previous Opinion.
The older view expressed by Sir A. Ramsay in his “ Geology of
North Wales”? (A) is too well known to require much explanation.
He regarded the felsite here exposed as a single mass which had
intruded into, and in places completely altered, the adjacent con-
glomerate. He based his view principally on the fact that the
matrix of the conglomerate closely resembles the felsite, even ‘to
the porphyritic crystals, the passage between the two being quite
gradual. We must not suppose that such a geologist as Sir A.
Ramsay was misled in this matter, as some subsequent writers have
suggested, by so simple a thing as the obscurity of the pebbles in
an unweathered block. On the contrary, more than one of these
writers have described the rocks in which his statements are
verifiable as felsites. Such rocks may be seen near the Llanberis
road, on the summit of the felsite crag in the tramway section, on
the slopes of Clegyr, and on Mynydd-y-cilgwyn, and here certainly
Sir A. Ramsay’s explanation is suggested, thongh further observa-
tions, here and elsewhere, render it untenable. When, however,
we reject it we must admit that a conglomerate can be deposited on
a felsite in such a way that it is impossible to say where one begins
and the other ends. His explanation also accounted for “the
capricious variation of the strata adjoining the porphyry,” which
otherwise might have suggested to him an unconformity.
The first attempt to upset Sir A. Ramsay’s explanation came
from Professor Hughes and Dr. Hicks, the latter publishing his
views (B) in 1878.’ He considered (1) the felsite at Moel Tryfaen
to belong to the same series as the rocks in the adit beneath the
hill, and (2) both to be overlain unconformably by the conglomerate ;
but he gave no proof of the latter conclusion beyond a supposed
N.W. dip of the “metamorphic rocks,” the Cambrian conglomerate
having, according to him, a N.E. dip. But he pointed out that the
conglomerates contained pebbles ‘‘ appearing to resemble the rocks
in siti near,” and stated of these conglomerates that “here, as in
all other Welsh areas, they strongly define the base of the Cambrian.”
Of the rocks of Llyn Padarn he says, “it is more than probable
that we have in the series here some contemporaneous lavas,” and
“‘the pebbles in the conglomerates are usually identical in character
with the rocks below.” He does not, however, point out what is
the nature of “the rocks below,” though they must have included
the felsite.
In 1879 Professor Bonney published a paper on the district (C).*
It gave the result. of “working over parts of the district [including
the Bangor area] on several days in September, 1878.” From |
internal evidence it would appear that the author visited Moel
Tryfaen and returned by the Bettws Garmon road, walked from
Cwm-y-glo to Llanberis by the railway, and returned part of the
1 Mem. Geol. Survey, vol. iii.
* Q.J.G.S., vol. xxxiv, pp. 147-152.
3 Q.J.G.S., vol. xxxv, pp. 309-320.
Rev. J. F. Blake—The Lianberis Unconformity. 171
way by the road, climbing the slopes above, and also went along
the tram-line on the other side of Llyn Padarn from the head of
the lake to Llys Dinorwig. He accounts for the differences between
himself and “ ihe officers of the Survey ” by their being “ occasionally
misled by the superficial aspect of the rocks.”
Part of this paper it is necessary to quote. Speaking of Moel
Tryfaen, he says: ‘The conglomerate contains pebbles of the same
purplish quartz-felsite, generally 2—4 inches diameter, but sometimes
a foot or more, together with angular fragments of purple slate.
On the western side about one-fourth of the fragments are felsite,
the remainder slate—green and purple, and a dull green grit
resembling one in the underlying series. “The fragments of purple
slate are rather more numerous. on the eastern side. The strike of
the conglomerate appeared to be about E.N.E. and W.S.W. :
and the bedding, as it seemed to us, dipped to the N.N.W. ata inf
angle, but . . it was difficult to be sure of this” [Dr. Hicks
had made the dip N.E.]. The quartz-felsite he takes to be a lava-
flow, because (1) it shows flow-structure in parts; (2) a band of
slate is intercalated in it and is not wou LemoNSTy altered; (8) it is
associated in places with an agglomerate. He also gives a section
along the tramway by Llyn “Padarn, which will be referred to
later on.
One among his conclusions is that “further examination will
probably discover more agglomerates, and perhaps further sub-
divide the lava-flows,”’ endl in speaking of Moel Tryfaen, ‘“‘ where
the quartz-felsite must be very thick,” says, ‘“‘appearances suggest
that there is a marked physical break between this [the Cambrian
conglomerate | and the subjacent sedimentary series.”
Up to this time, therefore, the only alternative to Sir A. Ramsay’s
view was, that there was a single conglomerate forming the base of
the Cambrian, and that it lay unconformably on. or was separated
by, a marked physical break from the rocks below, whether felsitic
or sedimentary, whose fragments also its pebbles resembled: the
only variation being that Professor Bonney figured the conglomerate
in his tramway section? as conformable, but said nothing about it in
his text.
In 1885 Professor Green (D) described part of this section,’
which he considered to show that “the conglomerate rests
on these rocks with the strongest possible unconformity.” As to
the age of the conglomerate, he only says that it is ‘‘taken to be
the base of the Cambrian rocks in that district.” At the reading of
1 All these reasons seem to me to have now disappeared. We have learned that
flow-structure may be found also in an intrusive rock (see Sir A. Geikie in G,
postea, p. 93), the “‘slate’’ is a greenstone dyke, and the agglomerate may be
a fault breccia. Even the proof of the. felsite being of earlier age than the con-
glomerate would not now, if that conglomerate is post- Llanberis, prove it to be
non-intrusive, and there remains only the fact that it is always followed, in regular
succession, by its own débris, or what is considered to be such, and ‘this seems
sufficient.
2 Op. cit., p. 315.
3 Q.J.G.8., vol. xli, pp. 74-79.
172 Rev. J. F. Blake—The Lianberis Unconformity.
this paper Professor Hughes expressed his agreement that here
“the newer series” is “absolutely unconformable to the older,”
and Dr. Hicks said that “from the present evidence it is clear that
an unconformity does exist.” Professor Bouney, however, said that
Professor Green’s reading of the section (which differed from his
own) might be the correct one, but he felt very doubtful.
It was this genera] consensus of recent opinion, that there were
Pre-Cambrian rocks exposed in this district, that led me to examine
it in connection with the Pre-Cambrian rocks of Anglesey, announcing
my results in 1888'(H). At the time of writing that paper I was
no better acquainted with this part of the district than other writers
upon it, but I was led to accept the recent opinions (1) that the
felsite was a lava-flow and not intrusive, and (2) that the con-
glomerate to the east was derived from it. But no evidence had
been given for regarding the conglomerate as the base of the
Cambrian, and accordingly I considered it might be high up in that
series. Nor could I then see proofs of unconformity at Moel Tryfaen,
while the unconformity shown by Professor Green I could not deny,
but I tried to discount it by quoting his opinion that it did not
necessarily indicate any great difference in age.? I thus considered
the felsite to be part of the Cambrian succession, in spite of accepting
all that previous writers had given reasons for. As to the con-
glomerate, quoting previous observers, I considered that the pebbles —
were of Cambrian age, and yet took the containing rock to be one
of the higher conglomerates in that series.
In 1891 Miss C. Raisin traversed my conclusions as above (F).°
In this paper, amongst many minor criticisms, she made one
of great weight (in addition to the correction about the “ slate”).
Speaking of Moel Tryfaen, she said: ‘“‘We should have to believe
that at some epoch, after the deposition of one of Mr. Blake’s
successive conglomerates, the slates of which we now speak were
deposited, indurated, modified, and worn down to form some of the
Moel Tryfaen pebbles—a process of rapid manufacture indeed.”
This was used as an argument for an unconformity below the
conglomerate, which she was then in favour of, even though she
could not observe it in Professor Green’s section, where she con-
sidered it as only “ locally absent.”
Five days previous to the reading of this paper Sir A. Geikie
treated of the district in his Presidential Address (G).4 He denied
that the conglomerate forms the base of the Cambrian, or is un-
conformable on the rocks below, and, in fact, he agreed exactly with
my then published views. But he could not see the unconformity
1 Q.J.G.8., vol. xliv, pp. 271-290.
* In this same paper I endeavoured to support the Cambrian age of the felsite
by finding its base. Therein | mistook a squeezed relic of a dyke for slate, with
the result that the section, which I thought proved my point, proved nothing, either
for or against it. In a later paper (F) Miss Raisin did me the service of pointing -
out this mistake, as I have much pleasure in acknowledging.
3 Q.J.G.S., vol. xlvii, pp. 329-342.
4 Tbid., Proc.
Rev. J. F. Blake—The Lianberis Unconformity. 173
where Professor Green described it, and was not, therefore, forced as
I was to discount its teaching.
In 1892 I published a detailed account of the Cambrian
succession (H),' from which it appeared that instead of there being
only one Cambrian conglomerate at the base, there were several at
different horizons in the series. The facts about the Llyn Padarn
felsite and conglomerate were postponed to a later paper. This
later paper (1), published in 1898,? is the one which has been
criticized by Professor Bonney and Miss Raisin conjointly in the
paper now being replied to (K).* Prior to the observations therein
recorded, most of which were entirely new, I had considered that
there was no unconformity beneath the Llyn Padarn — Moel
Tryfaen conglomerate, except the supposed local one shown by
Professor Green, but these observations forced me to conclude that
Professor Hughes and Dr. Hicks were right in their conjecture that
such an unconformity occurred, and that it indicated, in the words
of Professor Bonney, a “marked physical break.” Notwithstanding
this, I still agreed with Sir A. Geikie in considering that there were
several conglomerates in the Cambrian series, each in relation to its
own felsite, but I removed from that series the great one at Moel
Tryfaen and Llyn Padarn.
It thus appears that at that time the whole difference of inter-
pretation rested solely on the question as to what were the rocks on
which the conglomerate lay unconformably. Dr. Hicks supposed
them to be Pre-Cambrian, because the samples he collected in the
Moel Tryfaen adit seemed more altered than the Cambrian rocks
with which he was acquainted. I held them to be part of the
ordinary Cambrian series. I was accompanied in the examination
of the adit section by Mr. Robert Lloyd, who has spent his life
amongst these rocks and knows them well, and he recognized them
at once by their local names. I also exhibited to the Geological
Society samples of all that I collected there, without anyone claiming
them as anything but Cambrian.
But, of course, this difference was fundamental. If the con-
glomerate in one place is unconformable to the rocks immediately
below the purple slates, we may reasonably expect that in other
places it will be unconformable to the latter also, as they follow the
former in regular sequence, and in this case the whole proof of
there being anything Pre-Cambrian here is entirely destroyed.
Under these circumstances it is certainly remarkable that Professor
Bonney and Miss Raisin, in their criticism upon my paper, do not
attempt to show that the rocks in the Moel Tryfaen adit are Pre-
Cambrian, but endeavour to demolish my stratigraphy, in which, if
successful, they would destroy their own former views and ap-
proximate to those which now, on further evidence, I have discarded,
and which were nevertheless equally fatal to the idea of there being
any proof of the existence of Pre-Cambrian rocks in the district.
1 Q.J.G.8., vol. xlvili, pp. 243-262.
2 Q.J.G.S., vol. xlix, pp. 441-466.
3 Q.J.G.8., vol. t, pp. 578-602.
174 Rev. J. F. Blake—The Llanberis Unconformity.
The various views on this district may now be thus summarized :
A. A general unconformity indicates the commencement of
a new series.— All.
B,. There is no unconformity in this district. — Ramsay ;
at Moel Tryfaen, Bonney, Raisin.
B,. The unconformity is local only.—Getkie, formerly Blake.
B,. The unconformity is general. — Hughes, Hicks, Blake ;
formerly Bonney, Raisin.
Conclusion 1. There is no break in the series here.—Ramsay,
Geikie, Bonney ? Raisin ? formerly Blake.
Conclusion 2. The great conglomerate forms the base of
a new system.—Hughes, Hicks, Blake; formerly Bonney,
Raisin.
C,. The Moel Tryfaen conglomerate is Cambrian, therefore
the underlying beds are Pre-Cambrian.—Hughes, Hicks ;
formerly Bonney, Raisin.
C,. The beds below the Moel Tryfaen conglomerate are
Cambrian; therefore there is no evidence of Pre-Cambrian
rocks here, and the age of the conglomerate is doubtful.—
Blake.
Professor Bonney and Miss Raisin’s general Objections.
The authors commence by characterizing my conclusions as
“a new and revolutionary hypothesis”; but it will be seen from the
foregoing account that the idea of an unconformity is by no means
new. The nature of the rocks in the Moel Tryfaen adit can scarcely
be called a “hypothesis,” and it is this that is revolutionary in its
results, the further extension of the unconformity, which no doubt
is new, being thus rendered quite natural. My suggestion also of
there being more than one felsite, had been anticipated by Professor
Bonney in C.
As a first objection my critics ask: “To what epoch (from the
Menevian onwards) do these so-called Post-Llanberis sediments
belong, and where in the adjacent districts may we find beds that
can be correlated with them?” “Of this problem,” they say, I have
not ‘succeeded in offering a solution.” When they wrote this they
cannot have considered my words (p. 465): “It seems to me most
probable that they are extensions of the immediately overlying
rocks.” These overlying rocks (the Bronllwyd Grit and_ its
associates) do not belong to any epoch from the Menevian onwards,
but lie below that formation and below all fossiliferous rocks, except
the Penrhyn pale slates with Conocoryphe viola. ‘The authors have
totally misunderstood my suggestion ; moreover, that suggestion
about the probable age of the conglomerate may be wrong without
affecting the question of the unconformity.
Next they take me to task for saying that we must see whether-
this unconformity be local or not, for according to them “ it can be
no local phenomenon.” Plainly it is because I take for granted
that a ‘marked physical break” (Bonney) can be no local
Rev. J. F. Blake—The Llanberis Unconformity. 175
phenomenon that I propose to see whether the supposed break is
local or not by way of testing its existence.
The next difficulty is “the necessity of twice uncovering the
felsite,” which, they say, I have “not even considered.” Certainly
I have not. Why should not felsite be uncovered twenty times in
the course of its history ? As I do not understand what the difficulty
is, | may be wrong in supposing it to result from a mixture of ideas.
It may be their idea that there is in this district an unconformable
conglomerate at the base of the Cambrian series, and it is my idea
that there is an unconformity above that series. I do not hoid both.
As to all the conglomerates but one, I accept Professor Hughes’ and
Sir A. Geikie’s explanations as to how a contemporaneous lava-flow
may be denuded before it is covered up by any other stratum, and
thus yield its pebbles to an overlying conglomerate. It is only
when the conglomerate has to lie on the felsite unconformably that
the latter wants uncovering.
The next difficulty is thus expressed: “Curiously enough the
Llanberis strata, though they have been so completely planed down,
have not contributed any large amount of fragments; only ex-
ceptionally do we find these or slaty pebbles of any kind, as, for
example, at Moel Tryfaen.” Here the authors give themselves
completely away. If there be a single pebble, exceptional or other-
wise, really deposited with the conglomerate and derived from the
Llanberis strata, then the former must be younger than the latter.
Probably the authors do not mean what the words imply, but for
“these” we must understand ‘‘ pebbles resembling these, but not
really derived from them.” Even then the statement reads curiously
with reference to Moel Tryfaen, after Professor Bonney’s description
in C, that about three-quarters of the pebbles on the western side
are “slate, green and purple,” etc., as quoted above, while “on
the eastern side the fragments of purple slate are rather more
numerous.” He then believed in the unconformity. The statement,
however, that the Moel Tryfaen conglomerate is exceptional in
containing slate pebbles is based on defective information. The
slopes of Y Big] show, in certain parts of the conglomerate, quite
a number of purple slate fragments, of such large size and so
angular that I really cannot suppose them to have come from any
distance ; and the workable slates close by are just like them. They
are found also on Mynydd-y-cilewyn and between Moel Rhiwen
and Moel-y-ci. We must remember, too, that purple slate is not
a kind of rock likely to be left in large fragments far from its source
of origin; it would soon break down into mud and form a new rock
like the original. Of this we find several examples, which render
the stratigraphy difficult.
So far from the alleged absence of pebbles of rocks like the
adjoining ones being a difficulty, their frequent presence and their
distribution are strongly in favour of an unconformity, as formerly
argued by Miss Raisin. It is these slate pebbles that distinguish,
when present, the great conglomerate from others which are intra-
formational. Sir A. Geikie proposed to account for them by the
176 Rev. J. F. Blake—The Lianberis Unconformity.
breaking up of the circumjacent deposits during a volcanic eruption,
but this explanation is untenable because, as pointed out by Dr.
Hicks, the pebbles are of rocks already cleaved. The conglomerate
runs in a long line, and its pebbles change character with the rock
near which it lies. Near the felsite it becomes most felsitic. On
Y Bigl and further north, as also at Moel Tryfaen and Mynydd-y-
celowyn, where it lies nearest purple slate, the fragments like that
rock are most abundant, and where at Moel Tryfaen it approaches
nearest the upper side of these slates, it contains strange, un-
recognizable fragments. In this it shows the character of a shore
deposit.
Although the general objections of my critics are thus disposed
of, I do not in the least demur to their conclusion, that “the detailed
evidence ought to be of the strongest and clearest nature if it is to
establish the supposed unconformity.” That is just what it is. -
The Moel Tryfaen District.
This is the district in which Professor Bonney (C) argued that
there was a marked physical break, and Miss Raisin (I) that we see
here the base of a series. But now that I give LeaUIH proofs of
the unconformity they cannot believe it.
Dealing with the summit conglomerate and the aril amount of |
any conglomerate in the adit section, these authors say ‘‘ there seems
on our theory no other explanation possible than that this con-
glomerate is fanlted out, and the broad outcrop at the summit
might be partly due to such disturbance.” We are not told,
however, what “our theory” is, nor where the conglomerate is
faulted out from, nor how much of the broad outcrop “might be”
due to such disturbance. This “explanation” is put forward
without any detail that should give us the slightest clue to its
meaning, and if we try to guess we are confronted with the puzzling
remark, “ this seems suggested by the changed dip in the associated
green grits on the summit.” What the dip was previously and
how determined we are not told, so I think it useless to speculate
on their meaning.
The authors disagree with me when I say that there is no green
grit on the summit. I will only remark that the green grit seen
by them is not the green grit which IJ referred to, which was one
occurring between the conglomerate and the purple slates, while, so
far as I can judge by the dip given, their “green grit” is part of
a small band of false-bedded grit associated with a different kind of
conglomerate of white weathering pebbles, near the opposite side
of the outcrop. Here one block shows the dip they state, N.N.W..,.
while an adjacent block shows the opposite, 8.8.E.
Referring to my description of the wide spread of conglomerates
and grits on the north side of the hill and their generally horizontal
trend in an east-and-west direction, the authors differ from me
again, at least by implication. I stated that there was a line of
crags showing a dip of not more than 5° to the east, and also in
a lower part a lenticle of fine grit running almost horizontally
Rev. J. F. Blake—The Lianberis Unconformity. ie
in a conglomerate. It is not positively stated that these observations
are incorrect, but only that “ we took the dip on several blocks and
surfaces, of which four at least were clearly shown varying from
15°—25° generally to the S. of E. or 8.H.” ; from which it is left to
be inferred that these statements are incompatible with mine.
But they are not. J have seen “blocks and surfaces” showing
the dips mentioned, but they are isolated blocks lying on the
eastern slope of the hill, and it is not certain that they are in siti.
I did not even look for dips on such blocks, as dips are worse than
useless unless the rocks are certainly in sitd. But even in that case
these dips, combined with the more persistent ones of the crags,
would not affect my argument to any material extent. But with
such rocks as these, and so exposed on the slopes of a rounded hill,
it is not by isolated dips, which are liable to all kinds of accidents,
but by the direction of the outcrops that the strike may best be
determined. In this case, if we walk on a level line round the base
of the north side of the hill a little above the pathway, we keep on
conglomerate, but if we anywhere mount a little and take another
contour-line, we keep upon grits. This would indicate that the
junction between them, i.e. bedding of both, was not far removed
from the horizontal in a direction across the hill.
The further remarks about this district are—(1) That the con-
glomerate of the lower crags is not like that of the summit, as it
does not contain the large slate pebbles. It is true that the pebbles
of cleaved rock with the appearance of slate are not so large as in
the latter, but there are many of them. (2) That whereas I said
of a certain area that it was all covered with conglomerate and grit,
in fact no small part consists of unbroken sward. This is only true
of that part which I called “the lower slopes,” and which I dis-
tinguished from the part all covered with conglomerate and grit.
(38) That it is remarkable that the conglomerate, if unconformable,
does not spread over on to the purple slates. This has not been
proved to be the case, and if true is easily explained. The fault
which bounds the purple slates is probably a thrust-plane which lifted
them and their covering above the level of the conglomerate on the
other side, and they have been worn back to that level by denudation,
which necessarily first removed the conglomerate. Probably also
ice has swept all débris away.
In this district, then, my critics have brought no valid objections
against my conclusions, and have failed to propose any reasonable
alternative. Meanwhile they have not touched the argument from
the great spread of the conglomerate and its associates over a very
wide area on the surface of the hill, while nothing but a 3 feet band
is found in the adit,! nor the still more cogent argument that, whereas
the conglomerate here lies on, or is next to, a great mass of banded
slate, in the neighbouring hill of Mynydd-y-cilgwyn it hes entirely
on felsite, and continues round to the western side of it.
1 I might add that this is not quite like the summit conglomerate, but such
arguments are of little value.
DECADE IV.—VOL. V.—NO. IV. 12,
178 Reports and Proceedings—Geological Society of London.
But I cannot understand what they would gain by success in their
contention. If instead of one unconformable conglomerate it were
granted that there were two or three conformable ones, they would
belong to the adit series, or to the purple slate series, or to both,
but in no case could they be the base of the Cambrian system, or
give any assistance in proving the existence of Pre-Cambrian rocks
in the neighbourhood.
(To be continued.)
Isa SOpsws) JNaN~p) 1-35 OO2I aD scINiGrS -
GeoLocicaL Socrrry oF Lonpon.
J.—February 2, 1898.—Dr. Henry Hicks, F.R.S., Presidents in the
Chair.
The President announced that Dr. Charles Barrois, Secretary of
the Organizing Committee of the Highth International Geological
Congress, which will be held in Paris in 1900, would shortly come
to London to invite the Geological Society to the Congress, and to
consult the Fellows with regard to the proposed excursions and the
subjects of discussion.
The following communications were read :—
1. ‘Contributions to the Glacial Geology of Spitzbergen.” By
B®. J. Garwood, Esq., M.A., F.G.S., and Dr. J. W. Gregory, F.G:S.
The extent of glaciation of Spitzbergen has been exaggerated,
for there is no immense ice-plateau, but normal glaciers with some
inland sheets and Piedmont glaciers. These differ from Alpine
glaciers, as they are not always formed from snow-fields at the head,
and though some of the glaciers (as the Baldhead Glacier) have
tapering snouts in front, most have vertical cliffs. _Chamberlin’s
explanation that the latter are due to the low angle of the sun is
insufficient, and they seem to be caused by the advance of the ice
by a rapid forward movement of its upper layers. The ice of these
upper layers falls off and forms talus in front, over which the
glacier advances, carrying detritus uphill with it, and producing
a series of thrusts. The Booming Glacier illustrates cases of erratics
carried in different directions by the same mass of ice.
The deposits of the Spitzbergen glaciers are of four types :—
(1) moraines of Swiss type; (2) those formed mainly of intraglacial
material; (8) those formed of redeposited beach-material ; (4) de-
posits of glacial rivers and reassorted drifts. ‘The materials of the
second are subangular and rounded ; scratched and polished pebbles
and boulders are abundant, and the fine-grained matrix, which is
frequently argillaceous, is often well laminated and false-bedded.
Some of these drifts are stratified, others unstratified, and contorted ©
drifts occur. This type of moraine is remarkably like some British
Boulder-clay. The third class is sometimes formed by land-ice, at
other times beneath the sea; the latter shows stratification. The
Reports and Proceedings—Geological Society of London. 179
superglacial and intraglacial streams, so far as seen, were usually
clear of drift. Under the fourth head an esker in a tributary of the
Sassendal is described. .
The direct geological action of the marine ice is of four kinds:
transport of material, contortion of shore-deposits, formation of small
ridges of boulder-terraces above sea-level, and striation, rounding,
and furrowing of rocks along the sea-shore.
Traces of former glaciation are described in the case of the Hecla
Hook beds, and of certain beds of late Mesozoic or early Cainozoic
age in Bunting Bluff. ;
Under the head of general conclusions, the authors state that they
have discovered no certain test to distinguish between the action of
land-ice and marine ice; that there is no evidence to prove that
land-ice can advance far across the sea; and that there is evidence,
which they regard as conclusive, of the uplift of materials by
land-ice. They note that the mechanical processes connected with
the advance of the glaciers are of three kinds. All the material
seen transported by the glaciers was superglacial or intraglacial, and
not subglacial. Some striation of intraglacial material is caused by
differential movement of different layers of ice. The advance and
retreat of the Spitzbergen glaciers is very irregular, and apparently
due to local changes. The observations of the authors support the
views of those who ascribe a limited erosive power to glaciers.
Lastly, the theory that glacial periods occurred as a consequence
of epeirogenic uplifts receives no support from Spitzbergen.
2. “Ona Quartz-rock in the Carboniferous Limestone of Derby-
shire.’ By H. H. Arnold-Bemrose, Esq., M-A., F.G.S.
The paper describes the occurrence in the field and the micro-
scopic structure of a rock consisting essentially of quartz, which is
found in the Mountain Limestone in several localities. It occurs
in irregularly-shaped bosses and veins, and shows no signs of
stratification.
Its close association with a quartzose limestone, which in turn
passes into an ordinary limestone with few, if any, quartz-crystals,
leads to the inference that it is a silicified limestone.
The microscopical structure of a number of thin slices of these
rocks is described. The quartz-rock is seen to be made up of
quartz-grains which generally interlock closely, but sometimes
possess a crystalline outline and contain zones of calcite. Fluor
is occasionally present.
The quartzose limestone is usually a foraminiferal limestone
containing a large percentage of quartz, which occurs as separate
crystals and as aggregates of crystals. The latter and the small
quartz-veins have a structure similar to that of the quartz-rock.
The former often contain zones of calcite and penetrate organisms.
The residue consists of quartz-crystals.
The author considers that the quartz-rock is not a gritty lime-
stone, altered by the growth of crystalline quartz around the detrital
grains, but that it is a limestone replaced by quartz. The gradual
180 Reports and Proceedings—Geological Society of London.
passage from the quartz-rock through a quartzose limestone to an
ordinary limestone, the presence of chert, of part of a foraminifer,
and of pieces of quartzose limestone in it, support the opinion that
it is an altered limestone.
J].—Annuat Generat Muerine.—February 18, 1898.
Dr. Henry Hicks, F.R.S., President, in the Chair.
The Secretaries read the Reports of the Council and of the
Library and Maseum Committee for the year 1897. In the former
the Council referred to the uninterrupted financial prosperity of the
Society and to the continued increase in the number of Fellows.
During 1897 the number of Fellows elected was 59: of these
41 qualified before the end of the year, making, with 13 previously
elected Fellows, a total accession of 54 in the course of the twelve-
month. During the same period, the losses by death, resignation,
and removal amounted to 51, the increase in the number of Fellows
being 3. ;
The total number of Fellows, Foreign Members, and Foreign
Correspondents, which on December 31st, 1896, was 1,329, stood
at 1,333 by the end of 1897.
The balance-sheet for the year 1897 showed receipts to the
amount of £3,610 19s. 3d. (including a balance of £768 3s. Od.
brought forward from the. previous year), and an expenditure of
£2,887 16s. 3d. There was an actual excess of expenditure over
current receipts of £45, but the excess was entirely due to
expenditure of a non-recurring character, and there still remained at
the end of 1897 a balance of £723 3s. available for the extraordinary
expenditure contemplated in the estimates submitted to the Fellows.
The completion of Vol. LIII of the Society’s Quarterly Journal
was announced, as also the publication of No. 4 of the Record of
Geological Literature added to the Society’s Library, and of Part II
of the General Index to the first Fifty Volumes of the Quarterly
Journal.
An address was presented to Her Majesty by the President and
Council, on their behalf and on that of the Fellows, on the occasion
of the Sixtieth Anniversary of her Accession; and three delegates
were nominated to represent the Society at the International
Geological Congress held at St. Petersburg.
The attention of the Council had been drawn by Sir Archibald
Geikie to the manuscript, in the Society’s possession, of part of the
Third Volume of Hutton’s “Theory of the Earth.” He had freely
offered his services as editor, and it was proposed’ to print and~
publish the work during the present year.
Reference was also made to the work done by the Committee
appointed in connection with the International Catalogue Committee,
and to the Index slips issued with the current number of the |
Quarterly Journal.
In conclusion the awards of the various medals and proceeds of
donation funds in the gift of the Society were announced.
Reports and Proceedings—Geological Society of London. 181
The report of the Library and Museum Committee enumerated
the large additions made to the Society’s Library during the past
year, and referred to the continuance of the work of labelling and
registering the specimens in the Museum by Mr. C. Davies Sherborn.
In handing the Wollaston Medal (awarded to Professor Ferdinand
Zirkel, F.M.G.S., of Leipzig) to Mr. J. J. H. Teall, for transmission
to the recipient, the President addressed him as follows :—Mr.
Teall :—
The Council of the Geological Society have this year awarded the Wollaston Medal
to Professor Zirkel, as a mark of their appreciation of the great services which he
has rendered to Geological Science, especially in the, department of Petrology. His
‘“ Lehrbuch der Petrographie,’’ the first edition of which was published more than
thirty years ago, is an indispensable adjunct to the library of every petrologist. A
comparison of the two editions of this monumental work, the second of which has
only recently appeared, illustrates in a most striking manner the enormous advance
which has taken place in petrographical science during the interval—an advance in
no small measure due to the influence exerted by Professor Zirkel, both as a teacher
and as an original worker.
His classic memoir on the ‘‘ Microscopic Structure and Composition of Basaltic
Rocks ’’ was one of the first publications in which the results of the examination of
an extensive series of microscopic sections were made known. It marks an epoch in
the history of petrography, not only because it greatly extended our knowledge
of this important group of rocks, but also because it gave a great stimulus to the study
of thin sections under the microscope. It must always be a source of gratification to
British geologists that this important work was dedicated to our distinguished Fellow
and revered master, Henry Clifton Sorby.
It is impossible for me to review all Professor Zirkel’s important contributions to
Geological and Mineralogical Science, but there is one other that I cannot pass over
in silence. I refer to his ‘‘ Geological Sketches of the West Coast of Scotland.’’
In this memoir Professor Zirkel applied the methods of microscopic analysis, for the
first time, to the wonderful records of Tertiary volcanic activity which abound in that
region. As an original observer he has made his mark in the history of our time,
and as a Professor he has won the esteem and affection of many enthusiastic students.
It only remains for me now to request you to transmit to Professor Zirkel this
Medal, and at the same time to express to him our great regard and our sincerest
wishes that he may long enjoy health and strength to continue his important
pene in those branches of Geological Science tor which he has already done
so much.
Mr. Teall, in reply, read the following letter, which he had
received from Professor Zirkel :—‘‘ Mr. President,—
‘“The honourable award of the Wollaston Medal is for me one of the most
gladdening events of my life. Yet I cannot say whether I am more pleased or
surprised at the unexpected announcement that I should be considered worthy
of so brilliant a distinction, which has been bestowed by this highest tribunal of
Geology only on the most illustrious British and Foreign votaries of the science. But
to-day all feelings are merged in one of gratitude to the Members of the Council,
who have taken so generous and favourable a view of my modest labours. As, much
to my regret and disappointment, I find myself unable to attend the Annual Meeting,
I must trespass upon your kindness to express by these written words my heartfelt
thanks and best acknowledgment for the great honour conferred upon me, of which
the most ambitious may well be proud. I receive the Medal asa token of indulgence
and encouragement, and it will be an incentive to me still to strive to be more worthy
of it and of your confidence. Probably I never should have been able to do
what I have done, but for the wise example and kind instruction of my old master,
Henry Clifton Sorby. The tie of personal friendship which connects me with so
many fellow-workers in your country since those bygone days, when Murchison,
Lyell, and Ramsay favoured the young foreigner with their attachment—this tie will
be strengthened to-day, and the Geological Society's prosperity and usefulness
will never cease to be the object of my warmest wishes.”’
182 Reports and Proceedings— Geological Society of London.
The President then handed the balance of the proceeds of the
Wollaston Donation Fund (awarded to Mr. HE. J. Garwood, M.A.,
F.G.S.) to Mr. A. Strahan, for transmission to the recipient,
addressing him as follows :—Mr. Strahan,—
At the last Meeting of the Geological Society we had the pleasure of listening to
a communication by Mr. Garwood and Dr. Gregory which adds much to our
knowledge concerning the Glacial Geology of Spitzbergen. Last year he also gave
an address at one of the ‘‘ At Homes’”’ of the Society, which was highly appreciated
by those present. These amply testify to his ability to carry on explorations in
difficult regions, where strength of purpose and special training are indispensable
to success. Other geological questions have also occupied his attention; and I may
here mention the paper by him in the Geological Magazine on ‘‘ Magnesian
Limestone Concretions’’ as an interesting contribution to a vexed question, and his
paper and reports on Carboniferous Fossils, the result of much labour among the
Carboniferous rocks of the North of England. The Council, in making him
this Award, hope that it may act as a stimulus to further researches in those fields in
which he has already shown such marked ability, and that he will accept it also
as a token of appreciation for what he has already accomplished.
Mr. Strahan, on behalf of the recipient, read the following
reply :—‘“‘ Mr. President, —
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Sir H. H. Howorth—Surface Geology of N. Europe. 195
by two coastal plains. The high plateau of Mexico, with levels up to
10,000 feet, here descends for a distance of 60 to 80 miles, to levels
of 2,000 to 4,000 feet, and at the divide is (as already stated) only,
about 1,006 feet above the level of the ocean ; but on both sides of the
saddle thers are. base-levels of lower altitudes. ‘The rock consists of
earthy sandstone ; and on the Pacific slope facing the city of Tehuan-
tepec are old sea- ‘cliffs and caves at levels of .400 feet. The floor of
the divide is traversed by a ‘‘ geological canal,” ata level of 776: feet
above’ the ocean, and. is fcowened iby enamel from, 4 to 8: feet in
depth, of quartz and soft sandstone pebbles, the latter being well
rounded ; this gravel is more thinly: scattered over the adjoining
slopes to a height-of 150 feet. The isthmus was evidently: swept
over by ocean-currents passing through the straits during sub-
mergence; and its elevation has been so recent that only short
canons have been. cut into the base-levels and. terraced plains
adjoining. Another line of communication was recognized at the
pass of Tarifa, a dozen miles eastward of that of Chivela above
described; and there are other current-swept depressions in’ this
region through which the waters on both sides are considered: to
have had intercommunication; though at higher levels. It should
be added that the stratified gravel of the divide:is continuous with
that covering the terraced plains on the Gulf side of the divide... °
The author considers ‘that this oceanic connection was as old. as
the Columbian (Mid-Pleistocene) epoch, and. was contemporaneous
with the great emergence of the: Antillean Continent’ and Hastern
America. It isa splendid illustration of the Lyellian- doctrine of
the interchange of. land and sea, which geological phenomena bear
testimony to from early, down to recent, times, and which serves as
ai key to many problems in terrestrial physics. Finally, it must not
be forgotten that the biological evidence of the former oceanic com-
munication across the Isthmus of Panama is not less clear than is
the physical. The late Dr. W.'B. Carpenter identified 35. species
of molluscs, out of 1,400 Pacific forms, as occurring on the Atlantic
side ‘of ‘this region; the number having. been since ‘increased: to
100 species, by the observation of Mr. Charles '. Simpson ;: while,
according to the late Dr. G. B. Goode, there is absolutely: no
resemblance between tae eee: -water fishes on the two sides of
Central America.
rie Bp, SeeracE GmoLoay or THE NortH oF EUROPE, AS ILLUS-
TRATED BY THE ASAR OR OsAR OF SCANDINAVIA AND FINLAND.
By Sir Henry H. Howorrn, K.C.1.E., M.P., F.R.S., F.G.S.
| | PLATE VII.
J N.a previous paper I ventured to emphasize the opinion, now very
generally held, that, whether by a gradual. process, or, spas-
modically, the Northern and, Central parts, of Scandinavia, have been
rising from the sea-level since Tertiary times, and that, so far as we
know, this rise has not been interrupted by intervals when the
movement has been one of depression. The movement has, in fact,
he Sue Jal, Jee, Howorth—Surface Geology of N. Europe.
been constantly in one direction. If this be true, it follows as
certainly as any physical fact follows its efficient cause that, other
conditions being the same, the climate of Scandinavia, like that of
Greenland, has been continually growing more severe, and is more
severe now, than it was when the higher Norwegian raised beaches
were deposited.
The other conditions, however, have, so far as we can judge, not
been uniform. One of them, and that a very important one, has in
all probability altered, and that is the one which gives Norway and
Britain their exceptional climate, and which diverts the isothermal
lines of Western Europe from their normal route across Asia and
America in places on the same latitude. This is the Gulf Stream.
There are very strong reasons (and I have formulated some of them
in my “Glacial Nightmare ”’) for believing that at the close of the
Tertiary period the so-called Gut of Florida was blocked by solid
land, and in consequence the warm waters of the Gulf of Mexico did
not then get into the North Atlantic. If the Gulf Stream were non-
existent, it is clear that the climate of the two sides of the Atlantic
would be more alike than they are now along the same latitudes.
That this was so is proved by the more Arctic types of molluscs
which then lived on the coasts of Scandinavia and Scotland, and by
the evidence of the existence of Alpine and Arctic plants at lower
levels and in lower latitudes in Western Hurope, as shown by
Nathorst and C. Reid. This conclusion is not only reasonable, but
seems incontrovertible. It does not mean that North-Western
Europe was then dominated by a Glacial climate and Glacial con-
ditions, but only that it was more or less assimilated in regard to its
climate to Canada and New England.
As we have also seen, the evidence is very strong and conclusive,
and has convinced almost every Swedish geologist, that not only has
the greater part of Scandinavia and Finland risen greatly in altitude
in the last geological period, but that this wide area has in a large
measure been actually submerged under the sea since Tertiary times,
and that its rise after this submergence was the last great fact which
affected its surface. .
I have argued that it was this submergence which did so much to
polish and mammillate its rock-surfaces, effects which I hold to be
the results in a very large measure of the eroding forces of the sea
in a tempestuous latitude, and not of the hypothetical ice-sheet of
which we have read so much. I will add another argument to those
already used. If the terraces on the Norwegian coast really mark,
as the Norwegian geologists argue, the differential rate of elevation
of the coast, which has caused the cutting back of the cliffs to be —
more rapid at one time than at another, it is clear that the polished
rock faces of Norway cannot be due to anything but the corroding
sea, for these faces have been worn back many feet while the coast
has been rising, and cannot therefore retain any polish or smoothness ~
they may have acquired in the times preceding the upheaval. If
they were polished by ice, the ice must have acted, not before, but
after the elevation, which is a reductio ad absurdum. Apart from
Sir H. H. Howorth—Surface Geology of N. Europe. 197
this, the facts presented by the general contour and face of the
country seem to me to inevitably point the same lesson. Whether
we examine the string of islands which fringe so much of the coast
of Scandinavia, and which project from the surrounding water like
so many gigantic whales’ or porpoises’ or turtles’ backs ; or whether
we examine the thousand islands of the Malar Sea or the Aland
Archipelago, with the same contours, or the mammillated surfaces
which the gneissic and granitic rocks of the interior districts of
Sweden and Finland bear, they seem to me to present a complete
parallel to the contour of the islands of the Arctic archipelago north
of America, and of the islands off the coast of Greenland, where the
lines of drift wood and the stranded whales far above high-water
most conclusively point to the whole land having recently risen
from the sea. In these latter cases, the Arctic navigators who
have seen the phenomena, and the geologists who have described
their voyages, have agreed that the North American archipelago and
the islands off Greenland have had their contours smoothed and
rounded by that most effective of denuding agencies, a shallow ocean
loaded with gravel and other débris, and not by an ice-sheet, which
does not in fact exist there. Nor, to take another illustration, can
we separate in any way, it seems to me, at Trollhattan and elsewhere
the polishing and smoothing of the interior and of the lips of the
Giants’ Cauldrons, which are confessedly the result of the aqueous
action just named, from the polishing of the inclined rock-surfaces on
which they occur. There is absolute continuity between them. ‘They
all seem to me to concur with the upraised shell-beds, the great
masses of false-bedded and stratified sands on the wide upland plains
of Dalecarlia, and the other evidences which have been collected by
the Swedish geologists, and to which I have referred in a previous
paper, to show, not that the country has been swathed in ice, but that
it has recently been the bed of a shallow and tempestuous sea. This
conclusion is of the highest importance. It is not, of course, new.
Without going back to the primitive geologists of the early part of
the last century, who wrote before the incubation of the Glacial
monster, it struck some of the very earliest critics of that theory,
who had examined the problem very thoroughly on the ground itself.
Bohtlingk, an experienced observer and a great traveller in
Lapmark and Finmark, to whom we owe the conclusive evidence
against polar ice-caps, says: “In Scandinavia, Finland, Lapland,
and the surrounding countries we find, to the height of 800 feet, the
most unquestionable marks of the constant retreat of the sea
occasioned by a continued rise of the land. In consequence of
this circumstance Scandinavia, during the first half of the alluvial
period, was still an island, and the tongues of land of Russian
Lapland, Finland, Esthonia, the government of Olonetz, as well
as those parts of the government of Archangel situated to the east
of the White Sea, were covered by the sea,” etc. (Hd. Journ.,
vol. xxxi, 1841, pp. 354, 355.)
Robert, the very able geologist of the Recherche Expedition,
writing as far back as 1848, says: ‘La mer me semblait polir,
WS Sip Jel JL, Howorth—Surface Geology of N. Europe.
canéler, creuser, rayer des roches de manieére a leur faire prendre la
physionomie de ceux qui s’offrent aujourd’hui un peu au dessus de
son niveau sur toutes les cétes de la Scandinavie.” Elsewhere he
concludes that the sea once occupied a large part of Russia, and that
Scandinavia then formed an archipelago. I have myself zigzagged
across Sweden in various directions on my recent third visit to that
country, and been continually impressed by the same conclusion. |
The most powerful and important evidence has yet to be quoted,
however, and it is forthcoming from what every intelligent person,
who has traversed Sweden with the view of studying its recent
geology, must consider to be in their way the most interesting and
stupendous phenomena probably in the world: I mean the Swedish
asar or osar. J am writing this paper in the very midst of them,
and have had some special opportunities of examining them. The
latest writer on Swedish geology, and one of the aiieees Nathorst, in
his ‘Sveriges Geologi,’ published in 1894, after examining the
various hea sea saline have been forthcoming to explain hein. has
to confess that the problem is still unsolved. To use his own words,
“‘vilja vi dock pa samma gang uttryckligen betona, att vi annu icke
betrakta fragan sasom slutligen afgjord ” (op. cit., p. 248)—“ we must
expressly state that we cannot consider (or look upon) the question
as finally settled.”
The asar are such a notable feature in the landscape of Sweden
that it is not surprising they should have been observed and their
peculiarities described at an early period. Their main features
were, in fact, pointed out by Swedenborg at the beginning of the
last century, and have been enlarged upon by every succeeding
explorer. The Swedish geologists divide the asar into two classes—
the asar properly so called, built up of masses of rolled stones, and
the sand-asar, composed chiefly of sand. While it is easy to find
specimens of each of these, it is also very easy to find others where
masses of rolled stones and beds of sand or of tough clay or brick-
earth pass into each other very much as they do in the Cromer cliffs.
A good example is the fine as upon which Upsala is built, and in
which we can study the internal structure admirably, since it has
been recently excavated right through (vide Pl. VII). There we can
see in the course of a few yards the passage from a mass of rounded
boulders into sand. The sand in some places is almost continuous,
and in others has banks of clay intercalated in it. The contour of
the asar, as Swedenborg long ago pointed out, differs with the
nature of their contents, the stony asar having steep sides, while
the sandy ones have much rounder outlines. The stones which
form such a great part of the asar (except certain specimens ~
occurring in their upper parts) are invariably rounded and water-
worn, and would be well described by the phrase applied to some
of the East Anglian gravels, viz. “cannon-shot gravel.” The asar
are found in all parts of Sweden from Scania to Norland, and in —
Hinland and Northern Russia they form, as is well known, huge
banks and ramparts. In some cases they run with great uniformity
in shape and breadth for long distances, their direction being
Sir H. H. Howorth—Surface Geology of N. Europe. 199
wonderfully continuous. So uniform are they that, as Brongniart
pointed out, the roads in some places, as from Upsala to Wendel,
from Hnkoping to Nora, from Hubbo to Moklinta, etc., run along
their crest. Sometimes they spread and widen out a little, forming
nodes like so many knots on a cord. Frequently the continuous
line is interrupted by a gap or a series of gaps, so that instead of
a uniform bank there are a number of huge circular or oval mounds.
They consist generally of a main trunk, with a number of small
subsidiary lateral branches running into them like the affluents of
a river, aud sometimes they have satellites attached to them in the
shape of eskers and kame-like mounds. ‘They are as sharply
marked off from the adjoining plain on either side as a railway
embankment is. In some cases, notably in Finland, they do not
run in parallel lines, but vary in direction, sometimes even crossing
each other, but in Sweden their direction is singularly parallel, as
may be seen from the admirable maps published by the Swedish
geologists, notably that by Tornebohm. The enormous size and
cubical contents of these gigantic mounds can only be appreciated by
those who have seen them on the spot and followed them for miles.
According to Erdmann, the well-known Upsala as, which runs
from the mouth of the Dalelf to Sddertom, south of Stockholm, is
about 200 kilometres long. The as of Koping, as far as it is at
present traced, from Nykdéping to the Dalelf, is about 240 kilometres
in length. The as of Enképing runs from near Trosa in Suder-
mannia to Loos in Helsingland, and is from 300 to 340 kilometres
long, while the as of Badelunda, running from Nyképing in Suder-
mannia to the parish of Réattvik in Dalecarlia, is about 300 kilometres
long. According to Erdmann, the asar west of the watershed
between Lake Wenern and Lake Wettern run N.N.E.-S.S8.W., while
east of that line they run from N.N.W. to 8.S.E.
Erdmann also gives the elevation at which some of the principal
asar have been traced. “In Jemteland, N.and N.W. of Storojo, to 1,000
or 1,200 feet; in Herjeadal, near Hede, to 1,300 or 1,400 feet; in
Daleearlia, in the parishes of Malung and Idre, to between 1,000 and
1,300 feet; in the government of Elfsborg, in Vestrogothland and east
of Ulricehamm, to 1,100 feet; at Jonképing, in Smialand, near to
Lake Almesikra, to about 1,000 feet ; but Tornebohm informed
Mr. Geikie that in the northern parts of the country they occur
at an elevation of 2,000 feet.” ‘Their height varies, the average
being about 50 or 100 feet high, but in many places they run up to
100 metres or more, while they sometimes sink to 20 or 80 feet.
Their breadth, too, varies, the normal breadth being from 80 to 50
paces, but in some cases, as at Upsala, where there is a spreading
node, their breadth runs to 200 or 250 yards. From these facts the
cubical contents of the asar may be guessed. They are often
somewhat wider and higher at their northern end, that is, at their
inception, than further on. In the low flat country their contour is
very uniform, but in the upper and more hilly districts, where they
chiefly abound, they have a tendency to become broken up into
strings of separate mounds and kame-like masses. Their materials,
200 Sir A. H. Howorth—Surface Geology of N. Europe.
in so far as they consist of boulders, have in every case where they
have travelled, and we can trace the mother rock in sit#, moved from
north to south, and were never in the reverse direction.
One of their most important features, and one which has been
a great deal too little noticed in the various theories which have been
forthcoming to explain them, is the fact that they traverse the
country quite irrespective of its contour, going uphill and downhill,
and athwart the natural drainage. On this point I will quote the
language of a first-rate authority, Erdmann. After saying that they
sometimes run along the valleys, sometimes on the mountain flanks,
and sometimes on the plateaux, he adds (in italics) the words : “C’est
ainsi qu’elles continuent leur cours lointain, franchissant les plateaux,
les vallées, et les plaines, et ne semblant en aucune maniére s'inquiéter
des reliefs divers actuels du pays.” (‘Hxposé,” ete., p. 41.) This
is a conclusion drawn from the Swedish asar. The Finnish ones are
quite as remarkable, traversing lakes and watersheds without any
hesitation.
As I have said, a large portion of the asar consist of masses of
rounded stones of various sizes up to 2 feet in diameter. These
rounded stones are not mixed with angular erratics. The latter,
when they occur, do so in the upper and more sandy and loamy
layers, or scattered over the dsar’s backs, nor, so far as I could observe,
do they contain stones of exceptional size. These, again, chiefly
occur in the sandy beds or on the backs of the asar. Their contents
are not sorted according to their size, but the stones generally lie
with their longer axes parallel to the direction of the as in which
they are found. The beds of sand and the sandy asar are in nearly
all cases more or less stratified. They are frequently false-bedded,
and the beds which show the false-bedding have their lines very
pronounced, the angular wedges of sand and the lenticular masses
being on a large scale and very marked. The uppermost layers of
the asar often consist of stiff blue clay or of finely sifted and
laminated brickearths, containing in places numbers of diatoms
and marine shells, but never, so far as I know, fresh-water débris
or land molluscs. These beds of brickearth and clay occur only
at the top of the &sar, where they are often intercalated with
sand beds very irregularly disposed, just as they are in the beds of
contorted drift in the Cromer cliffs, and they are generally continuous
with the mantle of similar loam that covers the intervening country.
I cannot follow Erdmann and Geikie in separating these superficial
layers in the asar from the beds below. So far as I can judge (and
here, again, the present condition of the cutting at Upsala is very
pregnant with meaning), they pass continuously down into them,
and are merely later phases of one deposit, just like the similar
phases we see in the drift beds of Hast Anglia. Lyell, Murchison,
and others, who examined the Asar with care and skill, and whose
judgment was in this case unwarped by a priori theories of the
origin of the asar, treated the superficial beds containing marine
shells as belonging to the same period as the lower beds, which are
barren and consist largely of boulders.
Sir H. H. Howorth—Surface Geology of N. Europe. 201
Let us now consider the theories which have been adopted to
explain the asar. In the very early days of the Glacial fever—if
I may coin an incongruous but not inappropriate phrase—when
Agassiz reigned supreme, they were pronounced to be moraines.
This conclusion is one of those which form the despair of rational
science, for beyond the fact that they are heaped-up mounds of earth
and stones, there does not seem to be a single feature about them
resembling moraines. The stones they contain are rounded, water-
worn boulders, in no way like glacier stones. Scratched stones, or
those with flat sides, are never found in them. The beds of sand
and clay they contain are sifted out and separated from the boulders,
and are stratified and absolutely different to the mixed-up hetero-
geneous “muck” forming moraine stuff. The shells they contain in
their upper layers are marine shells, many of them perfect and of
very delicate texture. Marine shells and diatoms are not the product
of ice-sheets or of glaciers, and do not occur in moraines. Putting
their contents aside, their other features are quite different to
moraines. Terminal moraines, which are the only kind of moraines
distinctly resembling some phases of the asar in contour, are always
planted athwart the line of march of the ice. The asar, on the
contrary, are all roughly parallel to the line in which the stones
have moved, and to the line also kept by the stria on the rocks.
If moraines at all, the &sar must therefore be medial or lateral
moraines. Who has ever seen lateral or medial moraines made up
of water-worn boulders and of stratified sands and brickearths con-
taining marine shells, or seen them ranged in a large series of
parallel mounds with subsidiary branches, and with no high lands
in between from which their contents could be derived? But
I need not press the argument further.
Berzelius, in a letter to Professor Leonhard written as far back as
1841, says: ‘Agassiz’ friend Desor visited us in September last
year, and on seeing the immense boulder deposits which in this
country are named Asar, stated without hesitation that these
phenomena could not be explained by glaciers, and that they were
not moraines.” (Q.J.G.8., iii, 76.)
Durocher also long ago analyzed the various features of the asar
in a masterly manner, comparing them point by point with moraines
and their structure, and showed how completely they differed from
them. Reclus, who, although not a professed geologist, has treated
geological problems with great intelligence in his great geographical
work, is not less emphatic in his conclusion. Murchison and
Verneuil and other “ old masters ” who examined the problem on the
ground were of the same opinion. Nor do I know of any Scandi-
navian geologist who now maintains the view that the asar are
moraines. If there be any geologists that do so anywhere, it must
be in America, where the most extravagant school of glacialists
survives, and where official geology is so dominant, and every officer
of the Survey is apparently so dragooned by the conditions of the
service, that they follow their bellwethers with commendable loyalty
and discipline.
.
P02) stipe Jal, Jel, ov orth Sangitce Geology of N. Europe.
If not moraines, what are the asar? Hisinger suggested that
they might be the remains of a gigantic denudation, the intervening
deposits having been swept away. This view, while it did not in
any way explain the internal structure of the asar, merely pro-
fessed to explain their external shape and distribution. It has
been completely analyzed by Térnebohm, and shown to be quite
untenable; nor do I know anyone who now holds it, or who in
fact professes to understand how such a denudation could come
about. What kind of diurnal or other denuding agency would
permit of these ramparts of soft materials remaining as they are
when the rest of the beds were swept out? Whence could it
come? How could it work so as to move up and down the country
irrespective of its contour? Where has the débris of the gigantic
denuding process gone to? How is it that the covering of the
asar, which is formed of finely levigated brickearths, is also the
covering of the intervening plains on either side? But I will not
argue against a cause which has no defenders, nor kill again the
corpses which Térnebohm slew.
Every Scandinavian geologist known to me now admits that the
asar are in some way the result of aqueous action. The contour
of their surface, the rounding and arrangement of the boulders in
them, with their longer axes symmetrically placed parallel to the —
lines of the ramparts, the stratified sands and laminated clays, the
current bedding, the presence of shells and diatoms, are all con-
clusive that the asar are the result of aqueous action in some form
or other; and Mr. James Geikie himself, who represents the high-
water level of English and Scotch glacialism, says “all geologists
admit that the asar are in the main water-formed accumulations.”
Erdmann, Térnebohm, Nathorst, and all the other Northern geologists
known to me, are of the same opinion. When we come, however,
to discuss the particular kind of aqueous agency to which the asar
may be assigned, and the method in which it worked, the unanimity
at once ceases.
The superficial resemblance of the asar, when drawn on a sheet
of paper, to rivers with a main trunk and branching off into
smaller affluents, perhaps first suggested the idea that they had
something to do with rivers and river action; a view which has
prevailed very considerably in textbooks, but which seems to me
to be absolutely untenable.
Two theories of the fluviatile origin of the asar have been pro-
pounded, one treating them as the result of subaerial rivers and
the other as subglacial streams. I would first criticize the general
theory of fluviatile origin. :
In the first place, as we have seen, the asar do not run
along level surfaces nor along continuous slopes; but they
frequently run up and down hill. Sometimes they are found —
at a height of 2,000 feet and sometimes only a few feet above
the sea-level, and they run up and down the undulating country
keeping the same general direction. Now whatever movements
are possible with ice under certain conditions, by which it may
°
Sir H. H. Howorth—Surface Geology of N. Europe. 203
be able to move up and down slightly undulating districts, and
sometimes to creep uphill to a moderate extent, it would be an
entirely new and surprising fact that water could do so, unless
contained in a pipe and forced up by pressure behind. This is an
initial difficulty of the first moment, and is in fact absolutely
conclusive. Water, except in a pipe, cannot move contrary to
gravity, cannot travel up and down hill, or mount a slope; and
it does not matter whether the water is in a channel open to the
sky, or in a channel covered with an arched tunnel of ice. It
is therefore impossible on this ground alone that the asar could
have been deposited by rivers of any kind, unless the contour of
the country has entirely and radically changed since they were
laid down. .
This is by no means the only. objection to the fluviatile
theory of the asar. Their shape, when viewed in section, is quite
opposed to a fluviatile origin. Rivers which run very slowly and
carry much mud, instead of depositing that mud entirely in deltas,
sometimes, no doubt, raise their own beds, like the lower Rhine
and some rivers of Eastern England do, and in this way make
themselves solid aqueducts along which they flow. These solid
aqueducts, however, have not the shape or contour of asar, with
their often steep and sharply inclined sides. ‘This contrast in
contour is even more marked in the heaps of débris which form
the beds of subglacial streams. Nor can I see how rivers of any
kind could raise their beds to the portentous height of the asar
and yet be so narrow. Rivers, again, must have banks, and if of
fluviatile origin the asar should form channels running along their
crests. The solid aqueducts we have experience of elsewhere are
none of them very high, but are always breached and broken
through after a time, when the river escapes and forms itself
another channel, leaving the old bed meandering like a gigantic
snake in the valley bottom. We cannot conceive such solid
aqueducts remaining intact until they have been raised to a height
of 300 or 400 feet.
Another difficulty presents itself when we compare the contents
of the asar with those of such river-channels as we can examine.
Rivers which elevate their beds by gradual deposits are necessarily
sluggish and slow-flowing rivers. When rapid, rivers become
scouring agencies and not depositing ones. How is it possible to
conceive of a sluggish river depositing these enormous masses of
cannon-shot gravel — not of laying down a few yards of such
gravel when there is an occasional rush in the stream, but a rampart
a hundred miles in length and fifty yards high? The position is
incredible. The Nile, the Rhine, the Indus, the Amazon, all these
deposit beds, but they are beds of finely sifted mud. Again, in
depositing stones, rapid rivers sift them according to their specific
gravity, and do not mingle them higgledy-piggledy as they are
mingled here. If it was a river that deposited these mountains
of boulders, it must have been a very violent torrential river, and
its force quite portentous along its whole course. If so, how is
204 Sir H. H. Howorth—Surface Geology of N. Europe.
it that it did not scour and move away all the sand and brickearth,
and carry them down to its lower reaches, instead of laying them
down along their whole course? All torrential rivers known to
me have clean-washed, stony, and gravelly beds, with deltas or
reaches lower down, formed of the lighter materials of denudation.
But in bespeaking torrential rivers of this kind in Sweden we
are postulating a virtual impossibility. The level of Sweden is'too
low and too flat to afford such rivers. To get rapid rivers we must
have steep slopes in their beds. Of course we have a rapid flow
enough at places like Trollhattan, on the Gota river, and in other
gorges where we have rapids like we have in the gorges of the
Rhine; but there is no deposit like an asar deposit in these gorges
now. We cannot conceive any deposit of any kind long remaining
in such places, nor does it seem possible that these gorges existed
when the asar were made. Elsewhere than at these gorges the
rivers of Sweden are quiet and slow-moving, and deposit, not great
masses of huge boulders, but sand and silt and mud. They must
have been slower and less efficient as dynamical instruments when
the level of the country was much lower, as apparently was the case
in Sweden in so-called Glacial times. Again, the rivers of Sweden
naturally flow from west to east, or N.W. to S.E., in channels in
which they drain the upper plateau by running downhill to the sea, -
while, as we have said, the asar run from north to south, right
across the present river-channels and right across the lines of
drainage of the country.
Again, rivers make deltas. When they have run their course,
and get on to fairly level ground, they deposit fan-like stretches of
mud and clay. There are no similar phenomena in the case of the
asar, which do not terminate as deltas at all, the flat spreads of
gravel sometimes occurring in connection with them being torrential,
and not like river deltas.
Rivers naturally have wider and wider channels as we move
away from their sources to their mouths, and as their supply of
water increases from their several feeders, and consequently as their
loads of débris increase. ‘This means that their beds become
wider and deeper as we proceed downwards along their course.
They are thus quite different to the more or less uniform ramparts
called asar, which chiefly differ in bulk in the fact that they are
bigger at their initial stage than later on.
It seems absolutely impossible to correlate the asar of Dalecarlia
and those of Finland, some of which actually cross one another,
and others are united by cross pieces, with any river-beds, whether
subaerial or subglacial. Again, rivers of any size generally contain —
fresh-water shells or other débris. The asar, on the contrary, when
they contain shells at all, contain marine shells only. Rivers do
not deposit marine shells.
Lastly, we must not forget that although we are considering the ©
asar as substantive phenomena apart altogether from other deposits,
it is only for convenience of treatment. We cannot, in fact, separate
the asar and their contents from the sporadic and other deposits of
Sir H. H. Howorth—Surface Geology of N. Europe. 205
the same kind occurring elsewhere. The asar are only heaped-up
ramparts of materials which occur in the areas lying between them
in a less prominent fashion, in some cases as scattered boulders, in
others as continuous beds of sand and gravel and_ brickearth.
Hspecially is this so with the brickearth or loam which often forms
their upper layers. This is really part of the continuous mantle of
the country. Such different deposits oceur virtually at all levels.
How is river action to account for these complementary phenomena ?
Rivers cannot spread over a whole country so vast as Sweden. They
would cease to be rivers, and would become quite transcendental,
like Baron Munchausen’s dreams, and if. they did so they would
interfere with each other’s beds, and the ramparts would have been
levelled down. It is clear that in finding an efficient cause for the asar
we must find one which will also explain the deposit of the drift
occurring outside them. Apart from and altogether beyond these
difficulties is the supreme meteorological objection as to whence the
rainfall was to come to fill these stupendous rivers, running parallel
to one another, quite near together, and forming such a web
of rivers as was never seen elsewhere. Where is the gathering-
ground and where are the watersheds which could produce such
a congeries of rivers? This is an important matter to those among
us who believe in inductive methods in science. It is apparently
of no consequence to those geological alchemists who are continually
engaged in extracting palm-oil out of paving-stones. We cannot
understand any meteorological or physical change which could
supply the necessary rainfall for such rivers.
On every possible ground, therefore, known to me it seems quite
impossible to connect the asar with river action. This is not my
view only; it was the view of my master, Murchison, also. He
says: “However it may be argued that in mountainous tracts
torrential rivers and their feeders may have descended as they do
now, and may thus have produced rounded materials in valleys,
the argument is, at all events, perfectly inapplicable to the formation
of the Swedish asar. These linear ridges have not only been
accumulated in long trainées and lengthened mounds on terraces
high above the valleys, but offer appearances entirely unlike those
produced by rivers.”
This view is, in fact, also endorsed by Professor James Geikie -
in regard to subaerial rivers. He says: ‘Banks of gravel and -
sand no doubt accumulate in the beds of rivers, but if the rivers:
were to disappear such banks would not form prominent ridges
rising abruptly above the general level of the surrounding land.
They would, moreover, coincide throughout any course with the
lowest level of the valley, but our asar, although they trend
with the general inclination of the land, do not slavishly follow
the line of lowest level, showing an independence of the minor
features of the ground, sometimes winding along one side of
a valley and sometimes along the other.” (‘‘ Great Ice Age,” p. 169.)
While Professor Geikie rejects Tornebohm’s theory of the asar
having been the result of the action of subaerial rivers, he is willing
206 we. i, Cowper Reed—On the Cheiruride.
to accept the notion of D. Hummel and P. W. Strand that they
may have resulted from the action of subglacial streams, and
apparently also favours that of Dr. Holst, who assigns them to
streams flowing over the surface of the ice. Now in regard to
these theories, it seems to be forgotten by every glacial geologist
that a subglacial river or a river flowing on the surface of a glacier
differs from other rivers merely in that it flows under a long tunnel
or archway of ice, or over a bed of ice instead of a bed of sand or
gravel. In every other respect it is a river, and every difficulty
which has been already pointed out in regard to the explanation of
the asar by river action of any kind is as potent and conclusive
against these postulated glacial or glacier rivers as it is against
ordinary rivers. In addition they present special difficulties of their
own. Let us first look at the theory of Holst. It is quite true
that when the sun beats upon the back of a glacier small streams
are sometimes seen on its, melting surface, which run for a few
yards and then disappear down a crack or a crevasse. Nowhere,
not even on the vast ice-plains of Greenland, do these small
streams now grow into rivers; and in order to do so we must
suppose that the ice was marked by no cracks or crevasses, and
in the particular case of Scandinavia that in a singularly broken
and uneven country an ice-mantle could exist without any crevasses
or cracks draining its surface. But suppose it could, whence could
it derive the materials for making gravel, or the great boulders, when
the whole country was, ex hypothesi, blanketed with ice, and no exposed
rocks were visible? And having got hold of rocky débris, how were
these supraglacial streams: to roll the millions of great boulders of
granite, gneiss, and basalt, which form so large a part of the asar,
into their rounded and water-worn shapes, and accumulate them in
dykes and embankments a hundred miles long and a hundred yards
high ? and how is it that the rest of the glacier’s back or some
part of it was not uniformly strewn with angular and unrolled, or
with rolled débris, which should have remained when the glacier
melted alongside of the asar? Assuredly the whole idea is
incredible, and it is incredible how sober, thoughtful men in our
century should have tried to impose it upon science.
(Lo be continued in owr next Number.)
II].—Notes on THE AFFINITIES OF THE GENERA OF THE
CHEIRURIDA.
By F. R. Cowrrtr Resp, M.A., F.G.S.
N a former number? of this Magazine the evolution of the sub-
genera of the single genus Cheirurus has been discussed, and ~
it is now proposed to examine the mutual relations of the other
genera of the Cheiruride. Some diversity of opinion has existed
as to the genera which may be grouped together to form this
family. Barrande? put only the following five genera into it:
Cheirurus, Spherexochus, Placoparia, Staurocephalus, and Deiphon.
1 Reed, Grou. Mae., Dec. IV, Vol. III (1896), pp. 117 and 161.
a Barrande, Syst. Sil. Bon os vol. i (1852), pp. 835 and 766.
F. R. Cowper Reed—On the Cheiruride. 207
The last-mentioned genus was only provisionally united with the
others. Salter,! while omitting Placoparia from the above list,
added Amphion, which Barrande placed in the family containing
Encrinurus, etc. The genus or subgenus Spherocoryphe was also
really included by Salter, but under the name of Staurocephalus ?
unicus. The genera Encrinurus, Cybele, and Zethus were also given
by Salter as belonging to the Cheiruride, but with a query
against each of them. Zittel? places the following genera in
this family: Cheirurus (with its subgenera, Cheirurus, s.s., Cyrto-
metopus, Spherocoryphe, Crotalocephalus, Eccoptocheile, Pseudospher-
exochus, and Nieszkowskia), Areia, Deiphow, Onychopyge, Placoparia,
Spherexochus, ? Crotalurus, Staurocephalus, Amphion, Diaphanometopus.
Of these, Crotalurus must certainly be at once removed to another
family and group, because of the course of its facial suture.’
More recently, Beecher,* in a valuable and suggestive paper
on the classification of trilobites, has enumerated the genera and
subgenera in this family thus: Cheirurus, Actinopeltis, Amphion,
Anacheirurus, Ceraurus, Crotalocephalus, Cyrtometopus, Deiphon,
Diaphanometopus, Eccoptocheile, Hemispherocoryphe, Nieszkowskia,
Onychopyge, Pseudospherexochus, Spherexochus, Spherocoryphe, Stauro-
cephalus, Youngia. Eliminating the subgenera we get the following:
Cheirurus, Amphion, Deiphon, Diaphanometopus, Onychopyge, Spher-
exochus, Spheerocoryphe, Staurocephalus, and Youngia. Spherocoryphe
must, in my opinion, be accorded generic rank. The genera Placoparia
and Areia are placed by Beecher in the HEncrinuride on account of
their larval features, which suggest their union with this more
primitive and less specialized family. In fact, he would apparently
regard these two genera as morphologically the lowest in the
phylogenetic list of the members of his order Proparia, which com-
prises the four families Encrinuride, Calymenidz, Cheiruridz, and
Phacopidee.
Omitting the imperfectly known and extra- European genus
Onychopyge, we may concentrate our attention on the other genera
which have been accorded a place in the Cheiruridee, and all of which
are found in Europe. The four genera Placoparia, Areia, Amphion,
and Diaphanometopus are those whose true position is most a matter
of doubt. Schmidt,® for instance, hesitates somewhat in retaining
the two last genera in the Cheiruride; and the different views of
Salter, Barrande, Zittel, and Beecher with regard to Amphion and
the others have been mentioned above. The question can only
be decided by the characters which one considers as essential
to the family. But it is a matter of minor importance how we
group together the genera in a system of classification, so long as
we understand their phylogenetic relations. In Areia, in the first
1 Salter, Mon. Brit. Trilob. Paleont. Soc. (1864), p. 2.
2 Handbuch der Palaontologie (1885), vol. ii, p. 616.
3 In Zittel’s ‘‘ Grundziige der Palaiontologie ’’ (1895), this genus is omitted from
the Cheiruridee.
4 Amer. Journ. Sci., vol. iii (1897), p. 89.
> Mem. Acad. Imp. Sci. St. Petersb., vol. xxx, No. 1 (1881): Rey. ostbalt.
Tril., Abth. i, pp. 190, 195.
208 Este Cowper Reed—On the Cheiruride.
place, the absence of facial sutures separates it from all the other
genera in the Cheiruride, while this feature, combined with the
absence of eyes, the pentamerous lobation of the head, the expanded
termination of the glabella, and the presence of the pleural row of
puncta on the neck segment (in A. Bohemica), and the close
resemblance of this segment to the thoracic segments are larval
features which indicate a very low stage of development and
a comparatively small amount of differentiation. The Bohemian
species of the subgenus “ecoptocheile resemble it in the row of
puncta on the inner portion of the pleura, the number of the
thoracic pleuree, and the notch on each side of the glabella in
the front border of the cephalon; and Barrande himself remarks
that