=
‘- ce
a
=
SSS
es
= oe esas =

\
Nevin
Mi Ni

cote
=
eo
eee
ae
=

aN
a

Hey i) Ae A
AR NC
Dee

hs
FPA ah RCE NUR BC EL
ae
i haiataly

i)
‘ 1)
i eet et i
i i ea

a ath G i

BSC ut tata at
at }
PHAN EAT Na Ng ga)

at het

re

fy

yeh Pa AY iat

rete teres

Hs hs
He

He

ia

S
oe
Aris

0,
Yy,
Y

fees ts

By
x y ~

al i 4

fn,

aac ices
: SE
roe lage

2
fi os
EY

roa

fly
YW

coors) Ma
a” 5S

é

|

ee W
' ri r

? /
7 y My
ui ie +
fi i
. i }
a) 7

ir
iv

THE

JOURNAL OF GEOLOGY:

YOLY- AUG OST 1807

MORAINES OF RECESSION AND THEIR SIGNIF-
([GANCE-IN-GLACIAL THEORY:

CONTENTS.
Introduction.
Value of the Cincinnati-Mackinac moraine series as a basis of interpretation.
Known periodic oscillations of climate.
Theoretical effect of precessional oscillations of climate upon the ice-sheet
Character of the glacial oscillations as revealed by the drift.
Probable rate of ice-sheet motion.
Englacial transportation and deposition.
Probable duration of the periods of glacial oscillation.
Superposition of the oscillation upon a greater and much longer climatic
variation.
Summary.

INTRODUCTION.

The principal facts which form the basis of this paper were
presented in an article read before the joint session of the
Geological Society of: America and Section E of the American
Association for the Advancement of Science at Buffalo in
August 1896.2, They may be briefly summarized as follows:

During parts of the seasons of 1893, 1895 and 1896 the writer
explored the eastern coast of Michigan southward from Mack-

* An abstract of this paper was read before the Geological Society of America at
Washington, December 31, 1896.

2*Glacial Succession in Eastern Michigan.’ Abstract in Am. Geol. for October
1896, p. 234.
WOls Ven NO. 5: 421

422 FRANK BURSLEY TAYLOR

inac straits chiefly with the object of tracing the old shore lines.
Incidentally, however, much information was gathered concern-
ing the terminal moraines which lie in the same area. Their
development and relations were found to be for the most part
very simple. Between Mackinac straits and Toledo, Ohio, five
moraines were found arranged in consecutive order or in series,
and the series is regarded as complete within this interval. The
work of the past season brought the moraines of Michigan into
connection with those of Ohio and Indiana where their relations
had been worked out by earlier observers—by G. K. Gilbert
and N. H. Winchell in northwestern Ohio, by C. R. Dryer in
northeastern Indiana, and by F. Leverett in western and south-
western Ohio.'

According to Mr. Leverett and Professor Chamberlin the
drift of the Wisconsin glacial epoch extends down into south-
western Ohio nearly to Cincinnati.? Near this place its farthest
limit is marked by a terminal moraine, and from this there is a
series of moraines extending northward to the Maumee valley.
Numbering the moraines up from the south the one that passes
through Defiance is the tenth. By the work of the several
observers mentioned, the whole interval from Cincinnati to the
Straits of Mackinac has been explored, and the sum of the ter-
minal moraines in the whole series is fifteen. And further, not

*GILBERT in the reports of the Geological Survey of Ohio, Vol. I, 1871, chap. xxi,
Pp: 357. WINCHELL in Proc. A. A. A. S., Vol. XXI, 1872, pp. 171-179; Geological Sur-
vey of Ohio, Vol. II, 1874, pp. 56, 431-433. DRYER in the 16th, 17th and 18th reports
of the State Geologist of Indiana, 1888 to 1894. LEVERETT in Am. Jour. Sci., Vol.
XLIII, 1892, pp. 281-297; Jour. GEOL., Vol. I, No. 2, 1893, pp. 129-146.

?Mr. LEVERETT speaks of this as “the later drift.” (Jour. GEOL., Vol. I, No.
2, p. 138.) PROFESSOR CHAMBERLIN afterwards applied the name “ East-Wisconsin
formation” to this drift, and the same is now known as the “ Wisconsin formation.”
(GEIKIE’s “Great Ice Age,” 1894, p. 763 and map opposite p. 727. Also in Jour.
GEOL., Vol. III, No. 3, pp. 270 and 275.) PROFESSOR CHAMBERLIN recognizes,
with a reservation of doubt, a division of the moraines of the Wisconsin formation
into “earlier” and “later” groups. (“Great Ice Age,” pp. 763-764.) But this
division would make very little difference in the conclusions reached here. For in the
Miami valley the first moraine north of Cincinnati is the only one belonging to the
earlier group. All the rest of the series northward to Mackinac belong to the later
group and are therefore a consecutive series in time.

MORAINES OF RECESSION 423

Scale of Miles.

10 2@ 38 48 SD 60 70 £0

LEGEUD

Moraines, landlaid

wes TRAE
sopetEy
sae ie —

'— Moraines, waterlaid "2:20 7

Interlolbate Moraines Gauge
Boulder Belts.
FB

Map showing Moraines of Recession between Cincinnati and Mackinac.

424 FRANK BURSLEY TAYLOR

only is it ascertained that there are fifteen moraines between
Cincinnati and Mackinac, but the conditions of glacial motion
and drift deposition were so simple along the entire line that it
is substantially certain that the series is full and complete.
Three more moraines in the same series, but possibly not con-
secutive, were found north of the straits. In making the count
the central axes of a connected series of wide open valleys was
followed—up the Miami valley, down the Maumee, up the
Detroit and St. Clair and thence northward along the west shore
of Lake Huron. This course was chosen because the ice motion
was naturally the freest in the open valleys where the resistance
was least, and the oscillations of the ice-front were recorded
there more distinctly than anywhere else. This line avoids all
interlobate and other morainic complexes and follows the valley
axes where the amplitude of the peripheral oscillations of the
ice-sheet was naturally greatest.

On examining the configuration of the individual moraines
and on comparing the intervals of distance between them (shown
on the accompanying map) it is apparent that the principal
irregularities of the moraine series are due to topographic influ-
ences. As the ice-sheet crept along it moved forward farthest
and fastest in low wide valleys like the St. Clair-Detroit valley,
and it lagged behind on the hills and highlands as on Blue
Mountain south of Georgian Bay, on the highlands south of the
Straits of Mackinac, and on the ‘‘thumb”’ between Saginaw Bay
and the south arm of Lake Huron. The relative width of the
valley and the relative height of the bounding highlands had a
considerable effect upon the amplitude of the oscillations at any
given point. For in a narrow valley, between relatively high
side lands, as was probably the case toa slight extent in the
Miami and Sciota valleys, the ice movement was cramped and
the amplitude of oscillation more or less reduced. The ice-lobes
that spread away southward from the Huron, Saginaw and Erie
lake basins were wonderfully sensitive to topography. Differ-
ences of level of the general land surface over which they moved
- amounting to as little as a hundred or even fifty feet determined

MORAINES OF RECESSION 425

the direction of flow and shaped the lobes. The intervals
between the moraines show some irregularity, but on a close
study of the relief of the region, with due allowance for its influ-
ence upon the ice-motion, it seems clear that if the uneven
features of the land surface had been wholly absent the moraine
series would have been perfectly regular, either with equal inter-
vals or intervals showing a regular order of variation.

VALUE OF THE CINCINNATI-MACKINAC MORAINE SERIES AS A BASIS
OF INTERPRETATION.

So far as known to the writer there is no other glaciated area
of like extent where a moraine series is found so simple and
complete as that between Cincinnati and Mackinac. Similar
moraine series are known in many other places—most notably
in the adjacent areas of the Sciota Valley in Ohio, in south-
western Michigan and northwestern Indiana, and in Illinois, Iowa,
Minnesota and the Dakotas, but in none of these regions are
the phenomena of equal simplicity or completeness. A few
moraines in series are known in the eastern states and New Eng-
land, and a few also in Europe, but in all these regions they fall
far short in comparison. The series of moraines extending
northeastward from Defiance to Rochester, N. Y., may ultimately
prove to be as good as that extending to Mackinac, but at the
present time it appears to be incomplete. Eastward from Cleve-
land especially the lower moraines are closely packed on the
steep northward slope. In the Dakota-Minnesota series Mr.
Upham finds twelve moraines,’ but it is perhaps somewhat doubt-
ful, as was recently pointed out by Professor Todd, whether all
these moraines are in one series.2. In Illinois, western Indiana
and southwestern Michigan, Mr. Leverett finds a number of
moraines in series, but there are overlaps in the area, and in Il1-
nois, especially, the individuals join and separate so often, form-

™The Glacial Lake Agassiz,’ by WARREN UPHAM; Monograph XXV, U. S.
Geological Survey, 1896, pp. 139-141. Also, Twenty-second Ann. Rept. Minn. Geol.
Survey, Part III, 1894, p. 45.

2“ A Revision of the Moraines of Minnesota,” by J. E. Topp. Abstract in Am.
Geol. for October, 1896, p. 225.

426 FRANK BURSLEY TAYLOR

ing a series of complex loops, that the system appears at pres-
ent confused and a complete and simple series is not easily
made out. The moraines of the Saginaw lobe in all probability
make a simple series of at least eight or ten members, but they
have not yet been fully explored. The chief element of con-
fusion in these several areas appears to be due mainly to the
influence of a relatively complex topography. There may have
been other causes of complexity, but the land relief is clearly
the most important.

The individual moraines of the Cincinnati-Mackinac series
are also as a rule simpler in their reliefs, in the curves by which
they cross the valleys, and the intervals between them are wider
and more regular. .Their relations to each other and to the
adjacent higher lands are also simpler.

On account of their completeness and simplicity, therefore,
the moraines of the Cincinnati-Mackinac series constitute the
best body of facts now known for the study of the cause of the
oscillations of the retreating ice-sheet, and there appears to be
little prospect of ever finding a better one. With few exceptions
a comparison of other moraine series shows at once that the
reason the Cincinnati-Mackinac series is so simple is that the
land relief which the ice encountered along this line was of the
simplest sort. Such a comparison in nearly every instance
strengthens the conclusion that if the ice-sheet had moved over
a perfectly plane surface the moraines would have been laid
down at regular intervals or else at intervals varying progress-
ively in a regular way. In short, the departure from perfect
simplicity and regularity in the moraine series of any ice-lobe
seems to be ina general way proportional to the magnitude,
number, and complexity of arrangement of the larger topo-
graphic features which it encounters.

KNOWN PERIODIC OSCILLATIONS OF CLIMATE.

It has been supposed by many, and apparently with good
reason, that northern lands were elevated to relatively high
altitudes during the Iceage. This is held by some to have been

MORAINES OF RECESSION 427

the chief causal condition. But whatever the cause of the Ice
age itself may have been, it seems hardly possible to account for
the moraines of recession by any scheme of ups and downs of
the solid earth. The moraines themselves indicate that the
oscillations of the ice-front were of a periodic nature, and there-
fore dependent upon the operation of a periodic cause. All
geological forces that are purely terrestrial are necessarily derived
from the interior of the earth, and there is no evidence that their
activities are periodic, although they may recur at irregular
intervals. Still less is it possible to conceive of true periodicity
in the surface manifestations of purely terrestrial forces, such, for
instance, as would be required to explain periodic movements of
elevation and subsidence over wide areas, especially where the
amount of the successive movements would have to be regulated
to the extreme nicety of progressive variation requisite to pro-
duce the climatic cause of the moraines of recession. All such
supposable terrestrial causes may therefore be safely put aside.

To find a source for periodic causes we are compelled to turn
to astronomy. According to established doctrines the only way
in which astronomical forces can be supposed to influence glaci-
ation is through climate. The annual period of climatic change
is so short that it is, of course, out of the question. A period
of climatic change in rounds of about thirty-five years has been
deduced by Forel and others from the study of the variations of
glaciers and of rainfall.* But, as will be shown farther on, this
too seems far too short. After this the only known period of
climatic variation is that due to the precession of the equinoxes,

1F.-A. FOREL. (Archives. Sci. Phys. Nat., May 15, 1886, p. 503.) Fore] points
out that the variations of rainfall and air temperature, as deduced by C. Lang, agree
with his own periods of variation in Alpine glaciers. (Also Am. Jour. Sci., for July
1886, p. 77.) In Forel’s latest writing on this subject (“Les Variations Periodiques
des Glaciers,” Genéve, 1895) he finds the grounds for deducing a definite period to be
rather unsatisfactory. He finds that glaciers of different sizes and lengths do not show
the effects of causes of advance or retreat synchronously. After a few seasons of
increased precipitation all glaciers tend to advance, but small ones advance sooner
than great ones so that they do not attain their maxima at the same time. A small

glacier will reach its maximum and get far back on its retreat before a greater glacier
attains its maximum advance —a result that is natural from the fact that the effects

428 FRANK BURSLEY TAYLOR

and the movement of the perihelion of the earth’s orbit. Mr.
G. K. Gilbert has used this period of climatic oscillation in con-
nection with another matter. His statement relating to the
length and variability of the precessional period is concise and
convenient. ‘The precessional period is about 26,000 years, but
the position of the perihelion also moves—for the most part in
a direction opposite to that of the equinoxes—and the resultant
of the two motions has an average period of about 21,000 years.
It is not absolutely regular, but ranges ordinarily within 10 per
cent. of its mean value, and exceptionally to 50 per cent. above
and below.’* The period at 21,000 years seems too long, but if
we take it at its minimum of 10,500 years, it may not be.?

THE THEORETICAL EFFECT OF PRECESSIONAL OSCILLATIONS OF
CLIMATE UPON THE ICE-SHEET.

Let us see in what manner the astronomical forces would work,
supposing the oscillation of the ice-front to be due to precession.
Precession is produced by the rotation of the axis or pole of the
earth around the pole of the ecliptic. The figure thus described
on the celestial sphere is not in reality a true circle, but for the
purposes of this paper it may be assumed that it is, without in
any way impairing the general truth or validity of the conclu-
sions reached. The general idea of the influence of precession
upon terrestrial climate has been so often discussed that it is
hardly necessary to dwell at length upon it here. But it is

of causes of advance orretreat proceed in waves downward from the névé to the end of
the ice-tongue. From this and other causes of complication he finds it hard to make
out clearly any regular period of variation. Nevertheless, it is probable that a thirty-
five-year period exists. The progress of investigation along this line is well summar-
ized by Professor H. F. Reid, “ Variations of Glaciers,” Jour. GEOL., Vol. III, No. 3,
1895, p. 278 et seq.

*“Sedimentary Measurement of Cretaceous Time,” by G. K. GILBERT. Jour.
GEOL., Vol. III, No. 2, 1895, pp. 121-127.

* There is a possibility that the period of precession during the glacial epoch was
considerably shorter than the minimum of the modern calculation. Perhaps the
chance of this seems very remote, but there are small changes going on, now appar-
ently secular, which in so great a lapse of time may prove to be periodic and may
come to be of prime importance in their effects on terrestrial climate.

MORAINES OF RECESSION 429

necessary to see ‘clearly how the position or place of the ice-
front is related to this kind of climatic change. The change of
climate from this cause does not go on with the rotation of the
earth’s pole pari passu. For the pole, under the simplified con-
ditions here postulated, moves in a circle and changes its posi-
tion at a uniform rate. The effect of this movement on climate
is to produce a periodic or oscillatory change to and fro between
two extremes or climaxes, and these changes go on inan endless
alternating series, from cold to warm, from warm to cold, from
cold to warm, and so on. In glacial times a climatic variation
of this sort, even if it were slight in amount, must have had its
effect on the ice-sheet. As climate grew more severe the ice-
sheet would advance its front all along and spread over a larger
area, and as climate moderated the ice-front would draw back
and the area of the ice-sheet would be reduced. Thus it may
be demonstrated that the effect of a precessional oscillation of
climate upon the ice-sheet would be to cause it to alternately
increase and decrease its area by a series of expansions and con-
tractions, and this process would necessarily be accompanied by
a corresponding series of alternate advances and retreats of the
ice-front. We are thus enabled to infer the character or manner
of the oscillations of the ice-front, supposing them to be due to
precession. They would obviously follow the manner of what
is called simple harmonic motion. If a wheel be made to rotate
on a fixed vertical axis a point or peg on its rim describes a cir-
cle when viewed from above. But if we look at the wheel edge-
wise, or from the side, the peg appears to move to and fro along
a straight line, more slowly near the ends, fastest in the middle,
and coming to rest for an instant at each extremity. The man-
ner of the apparent motion is like the swinging of a pendulum
viewed from below... This is the manner in which the forward
and backward movements of the ice-front would take place if
produced by precession. As the cold increased after a warm
climax, the ice-front would advance, at first slowly, but at increas-
ing rate, until the middle point of the oscillation was reached ;
then more and more slowly until it came to rest at its cold or

430 ' FRANK BURSLEY TAYLOR

forward climax, where it would halt and build a terminal moraine.
Then as climate ameliorated the ice-front would retreat in the
same fashion and at its warm or backward climax it would again
halt and build a moraine. The moraines of the cold climaxes
would always be built after an advance movement, and would
therefore be left standing. But the moraines of the warm cli-
maxes would always be built after retreats and just before
advances, and would therefore be overridden and destroyed.
From these considerations it is plain that the time during which
the ice-front would stand at or near its extreme forward position
while building its terminal moraine at the cold climax would be
only a fraction of the whole precessional period. The precise
value of this fraction depends upon three factors: (1) on the
period or duration of the precessional oscillation of climate; (2)
on the amplitude of the oscillation of the ice-front, and (3) on
the width of the drift belt which takes the form of a terminal
moraine at the cold climax. The character of the moraine built
would vary considerably according to the manner of combina-
tion of long or short periods with small or great amplitudes.
Other factors, such as the quality and quantity of the drift, the
land relief, the situation with reference to the margin of the
lobe (frontal or interlobate), latitude and local climatic influ-
ences modify the character of the moraines more or less, but
need not be discussed further here.

By way of illustration let us consider a hypothetical case
Suppose the amplitude of oscillation to be thirty miles, which is
probably not far wrong for certain localities, and the period to
be 10,000 years, which is in round numbers the supposed mini-
mum value of the precessional period. The moraines are from
two to ten miles wide, the average being not far from five.
Their width varies considerably in different regions and different
situations, but the figures given are approximately true for north-
western Ohio, northeastern Indiana, and southeastern Michigan

Figure I represents a simple harmonic motion in which
ABCD is the circle of reference and represents the circle which
the pole of the earth describes on the celestial sphere in 10,000

MORAINES OF RECESSION 431

years. The diameter A C may be taken to represent the amplitude
of the oscillation of the ice-front as affected by the precessional
oscillation of climate, and is put at thirty miles. Of course the
ice keeps melting as it moves forward so that there is no material
thing that constantly accompanies the ice-front as it changes its
position. But we may imagine a point which shall keep its
place constantly at the front edge. This point would move to

Cold

and fro with the ice-front on the line A C, following the order
of the precessional changes of climate. An arrow within the
circle shows the direction of the general glacial flow, which is
maintained in the glacier itself through all phases of advance
and retreat of the ice-front. The climaxes of cold will therefore
be at A and the climaxes of warmth at C, and the ice-front will
have a period of rest at each of these points. When the ice-
front passes O it will always be moving at the maximum rate,
whether of advance or retreat. As the ice-front moved forward
from O to A its rate of advance would decrease, and would
become very slow on approaching near to A, and the retreat

432 FRANK BURSLEY TAYLOR

from A to O would have the same character in reverse order.
The five miles nearest to dA represents the approximate width of
the belt in which terminal moraines at the cold climaxes are
built. If the whole period of precession be 10,000 years and
the amplitude thirty miles, it is easy to show that the ice-front
would be within the five-mile belt (60’) about 2700 years, and
within the three-mile belt (@az’) about 2075 years. A period of
terminal moraine building of the same duration would also take
place at C, the warm end of the oscillation, but the moraines
built there would always be overrun and destroyed at the next
advance.

If this process were carried on with ideal simplicity the result-
ing forms of the terminal moraines at the two extremes of oscil-
lation would be substantially as represented in cross section in
the figure. Those at A would have relatively short, steep front
slopes and long, gentle back slopes, while those at C would have
long, gentle front slopes and short, steep back slopes. In the
moraine series as we have it, all those made at C have been
destroyed, and we have left only those made at A. We shall
see presently that where the conditions were simplest the
moraines do in fact show plainly a tendency to take the form
shown at A.

If the period of precession were 20,000 years, the amplitude
remaining the same, the time of the ice-front in the five-mile
belt would be doubled, or 5400 years. On the other hand, if
the period were 5000 years the time in the five-mile moraine
belt would be 1350 years, and in the three-mile belt 1037 years.

The character of the moraine would also be affected by the
amplitude of the oscillation, the period remaining the same.
The amplitude would necessarily vary greatly in different places,
the chief determining condition being the character of the land
relief and the relation of the ice to it. Against a steep slope
towards the ice the oscillation would be greatly reduced and
the moraines would be closely packed together, as is seen in
interlobate areas. In wide flat areas, like the Saint Clair-Detroit
and Maumee valleys, the amplitude would be at its greatest.

MORAINES OF RECESSION 433

The general application of this idea to the oscillations that took
place is plain on a comparison of the course of any two contig-
uous moraines of the series from their apexes in the center of
the valley to their turning point in the interlobate. The Fort
Wayne and Defiance moraines are nearly fifty miles apart at
their apexes, but they converge as they rise toward the north-
east until they are only eight or ten miles apart a few miles
beyond Adrian. On this basis it would be expected, further,
that the moraines themselves would be comparatively wide and
flat where the amplitude of oscillation was great and vice versa
Here again there is some evidence of agreement of fact with
theory. With the period of oscillation at 10,000 years and the
amplitude at 100 miles, which appears to have been its approx-
imate measure after passing Fort Wayne, the five-mile moraine
belt would be occupied by the ice-front about 1345 years, and
a ten-mile belt about 1920 years.

THE CHARACTER OF THE GLACIAL OSCILLATIONS AS REVEALED BY
EES DRE AGS

Assuming that the moraine series was produced by a climate
oscillation it becomes a matter of the highest importance to
discover if possible what the character of that oscillation was
Did the ice-front merely retreat and halt in the simplest possi-
ble rhythmic fashion, or did it follow a more complicated move-
ment of alternate retreats and readvances with halts between ?
It would be expected that the way in which it was built would
make some difference in the form or shape of a moraine. If
the moraines took any dominant or common form, and if that
shape corresponded to one that would result theoretically from
some particular process, it would be fair to presume that that
had been the method of their building.

At a first glance it would appear that the moraines show no
recurrent features that are particularly suggestive in this respect,
and it must be admitted that many of them, perhaps the major-
ity, do not. At least they do not show such features clearly
enough to be readily recognized. But there are some of the

434 FRANK BURSLEY TAYLOR

moraines that do show a marked tendency to take a particular
form, and it is upon these that we must rely.

Here again it is necessary to recur to the law of the higher
value of the simplest phenomena as a basis of interpretation
when compared with those that are more complex. If in the
present state of our knowledge we go to the compounded
moraines of interlobate areas, or to the more-or less obscure
moraines of the mountains or hilly eastern states, it will be
found very difficult to reach any satisfactory conclusion. But
some of the moraines of northern Indiana, northwestern Ohio,
and southeastern Michigan present the utmost simplicity of form,
and were built under the operation of forces acting in the freest
and simplest way possible. Upon these moraines, and especially
upon those of them that seem to be most typical in their sim-
plicity, I rely mainly for the conclusions reached.

The moraines of northeastern Indiana have been studied in
detail by Professor C. R. Dryer, from whose report I quote as
follows:

The peculiar topography of the Wabash-Erie region in Indiana would be
strikingly shown by a section along any line radiating southwesterly or
northwesterly from ‘Paulding, Ohio. Such a line would run nearly level
across the Maumee Lake bottom to the Van Wert and Hicksville Ridge, then
rise 80 to 1oo feet in four or five miles to the crest of the St. Marys and St.
Joseph moraine, then fall fifty feet in about one mile, then cross a level inter-
val of from one to ten miles, then show a second gradual rise and more
abrupt fall, across the Wabash-Aboite moraine, and the second terrace aver-
aging about sixty feet higher than the first. In the southern portion two more
terraces lie beyond the Wabash Ridge.

* Sixteenth Ann. Report of Indiana State Geologist, 1888, p. 123.

My attention was first called to the remarkable series of terminal moraines in
northeastern Indiana and northwestern Ohio by the work of Professor Charles R.
Dryer in the summer of 1886. As assistant to the state geologist, Professor Dryer
was at that time making a survey of the northeastern counties of Indiana. Some
acquaintance with the features of eastern Indiana southward as far as southern Ran-
dolph county and also with the region around Saginaw Bay in Michigan led me to
extend the series provisionally, recognizing its probable incompleteness, to those
regions. The idea that these moraines might mark precessional variations of climate
was adopted by me then as a tentative hypothesis. The drift of opinion since then
among American geologists, however, has been largely against anything like so

MORAINES OF RECESSION 435

This is distinctly the character that should be expected in
moraines built at a climax of advance in which the advance, the
halt and the subsequent retreat take place after the manner of
the cold climax of an oscillation like that shown at 4 in Fig. 1
above. The crest of the ridge is toward the front edge, the back
slope is long and gentle, while the front slope is shorter and

wa)
SO
Glacial Flow & b: L
ie ~ > SOOT ES
a re ea

DICE: an wae
[io ae ea ee er)

400 feet above datum

40 miles from Toledo YS 50

Fic. 2. Profile of Defiance Moraine.

steeper. This type of moraine is well illustrated in cross section

by the profile of the Wabash Railway as it passes over the

Defiance moraine east of that place. This is shown in Fig. 2.
As shown on this profile the crest of the moraine rises above

liberal an allowance of time for the glacial retreat as this hypothesis would seem to
require. Moreover the moraine series remained fragmentary and incomplete until a
year or so ago, so that there was not a sufficient foundation of fact to warrant the
presentation of the idea. Nor had the remarkable Greenland explorations of Cham-
berlin, Salisbury, and others furnished the present strong foundation for the idea of
slow motion of ice-sheets and slow transportation and deposition of drift. Without
adopting the idea of precession as a cause, Professor Dryer fully recognized the gen-
eral significance of the moraines, as the following words from his report show. After
speaking of the possibility that each moraine marks the culmination of a separate
glacial epoch, he says: ‘It seems more probable, however, that they are moraines of
recession and mark halting places in the retreat of one and the same ice lobe. When
their uniformity of mass, strict parallelism and occurrence at regular intervals are
taken into account, the whole arrangement will perhaps prove to be unique among
the glacial phenomena of North America. Their greatest importance lies in the
evidence which they afford of regular periodical oscillations of climate. The outer
edge of the ice lobe occupied a certain position long enough to form a moraine five
miles wide and I1oo feet high; it then fell back fifteen miles and occupied another
line long enough to form a similar moraine. These alternating halts and retreats
were repeated four or five times, the last retreat being thirty [fifty ?] miles, and the
last moraine, the Blanchard Ridge of Winchell, being smaller and less symmetrical”

(p. 124).

436 FRANK BURSLEY TAYLOR

its base somewhat more than forty feet, but the real crest is
somewhat higher than the railroad track. The front or western
slope is about two and a half miles long and the eastern or back
slope about seven miles. It has been suggested that the
moraines that show this form owe their steeper front slopes to
the action of marginal glacial rivers which have carried off the
deposit on that side. No doubt there was a slight influence of
this kind in some cases, but there certainly was none in the case
of the Defiance moraine, for it was laid down in about sixty feet
of still water (glacial Lake Maumee) and there was no chance
for a stream to act until the ice-front had retreated beyond
Detroit nearly to Port Huron. While the Leipsic beach was
being made the water still stood about thirty feet deep -at
Defiance, and it was only when it fell to the level of Lake Whit-
tlesey (Belmore beach) that marginal rivers began to exist. The
depression shown at Defiance in the profile is the bed of the
Maumee River which began to flow at the same time. But the
Maumee is a much larger stream than Tiffin or Bean Creek that
comes in from the north along the moraine front, or the Auglaise
River, which comes in from the south in the same relation.
Formed under such circumstances it is obvious that the Defiance
moraine was originally shaped in the building as we find it now,
and does not owe its form to the action of a border river. Part
of the Saginaw moraine, between Ubly and Cass City was prob-
ably steepened by the large rapid outlet river which flowed along
its front, but apparently none of the other moraines of this type
were notably affected in this way. The rest of the Saginaw
moraine is a fine specimen of the type here referred to.”

This character of the moraines, however, is not confined to
the particular tri-state area mentioned above. The same general
type is only a little less distinctly developed in several other
places, and is recognized by other observers. Mr. Leverett,

*Some account of Lake Whittlesey and the Saginaw and Port Huron moraines
with brief mention also of the Toledo and Detroit moraines may be found in “ Cor-
relation of Erie-Huron Beaches with Outlets and Moraines in Southeastern Michigan,”
Bull. G. S. A., Vol. VIII, 1897, pp. 31-58. Also “Glacial Succession in Eastern
Michigan,” abstract in Am. Geol., Oct. 1896, p. 234.

MORAINES OF RECESSION 437

speaking of the glacial drift of the northeastern third of Illinois,
says :

In the portion of the state covered by the newer drift there is a succession
of morainic ridges formed by the ice-sheet during its retreat from the Shelby-
ville moraine. These ridges are separated by drift plains or basins from a mile
or two up to thirty or forty miles in width. These plains usually show a
gradual rise on their landward (west and south) borders, while on the iceward
borders (toward the Lake Michigan basin) they are found to rise abruptly to
a moraine. The streams which now drain this region naturally choose the
axes of these basins for their main channels while the slopes carry the trib-
utaries. It is the long slopes on the west and south, and the short slopes on
the opposite side which have caused the tributaries of the streams to be
mainly from the west and south.*

It will be noted that Mr. Leverett speaks of the slopes of the
plains rather than of the moraines. Each moraine, however,
may be regarded in some sense as the projecting upward edge
of the gently inclined plain that merges with its back slope.
Professor Todd notes this relation in his description of the
moraines of Dakota where he says:

It is assumed that the reader is familiar with the generally recognized
features of drift formations, such as the undulating topography and the series
of drift deposits, covering an area with successive layers of till in a manner
which might be compared to a nest of spoons of assorted sizes, the smaller
lying inside the larger. Of these spoon-shaped deposits, the moraines form
the outer rims.?

It is very gratifying to be able to add to the weight of the
foregoing opinions that of Professor Chamberlin, whose study of
glacial problems has been close and prolonged, and whose
experience in observation is probably wider than that of any
other one man. It is hardly less than remarkable that his views of
the glacial retreat should accord so closely with the requirements
of the hypothesis here presented.

But so far as known to the writer this manner of glacial

t** The Water Resources of Illinois,” by FRANK LEVERETT. Extract from 17th
Ann. Rep. U. S. Geol. Surv., 1895-6, p. 13. Also in “Pleistocene Features and
Deposits of the Chicago Area,” Chicago Academy of Science, Bull. No. II, May 1897
py.

2““The Moraines of the Missouri Coteau and their Attendant Deposits,” by JAMEs
E. Topp, Bull. U. S. Geol. Sur. No. 144, 1896, p. 11.

438 FRANK BURSLEY TAYLOR

retreat has not been associated by Professor Chamberlin with the
causes here suggested. According to his view the drift of each
main ice invasion was laid down in imbricate fashion; that is,
there wasa continual oscillation with moderate readvances as the
general retreat progressed, so that the drift was laid down in
successive overlapping sheets somewhat like the weatherboards
on a frame house, or the shingle rows on a roof. In Geikie’s
Great Ice Age, under ‘‘The Imbrication of the Drift Series,’
beginning on page 736, his views are given as follows:

The drift deposits of the great plain region of North America may be
looked upon as a series of sheets overlapping each other in imbricate fashion;
the outermost disappearing beneath the next inner, and this, in turn, dipping
beneath the succeeding, and so on. The outer uncovered zone of each sheet
retains its original form, except as modified by superficial agencies, but the
inner buried zone was much modified by the over-riding ice during the later
advances. Ina general view of the drift, itis important to grasp clearly this
conception of the overlapping of the sheets, and to distinguish this imbricate
structure from the simple stratigraphical superposition of marine sediments
on the one hand, and of simple morainic corrugations following each other
in concentric recessional lines on the other. It is, furthermore, important to
observe that this is only a superficial conception of the drift series. Theoret-
ically, there are at least two of these imbricate series for every period of gla-
ciation, and the order of imbrication takes on opposite phases. During the
first part of the glaciation, when the ice on the whole was extending, though
by alternate advances and retreats, the later were generally greater than the
earlier advances. During the succeeding stage, however, when the ice was,
on the whole, retiring (though by oscillations) the later advances generally
fell short of the earlier. Inthe case of the lower or older series of glacial
accumulations, therefore, the later deposits generally reach farther south than
the earlier ones, whereas, during the recessional stages of glaciation, the
earlier sheets extend farther south than the later. These two imbricate series
of sheets of contrasted order represent the two great halves of a period of
glaciation. If there were two or more entirely distinct periods of glaciation
theoretically the double imbricate series repeated itself accordingly. .. .

There is one other class of facts that may ultimately be
added to the proof of readvances in the oscillations. Bowlder
belts, at least in certain situations, are believed to indicate read-
vances. Respecting the source of the bowlders themselves it
seems safe to say that ninety-nine out of every one hundred in

MORAINES OF RECESSION 439

western Ohio, in Indiana, and Illinois are of Canadian origin,
and nearly all are of the hardest crystalline varieties. Consid-
ering the dominant englacial mode of transportation, the contin-
ual and very complicated changes in the direction of glacial
flow and the dispersion from the lobate axes, it becomes
extremely difficult, if not altogether impossible, to account for the
bowlder belts except by the intervention of some later agency
of bowlder concentration—some agency that operated near
where the bowlder belts are now found. It seems impossible
that any marked bowlder belt could have been brought all the
way from Canada with the bowlders in such close relationship as
that in which they now lie. Some of the bowlder belts of
southwestern Ohio, southeastern and western Indiana are very
pronounced in their development. It is conceivable that they
might have been formed by the marginal concentration of super-
glacial or englacial bowlder trains, but it is hard to think of
those trains as coming directly all the way from Canada." The
distribution of bowlder belts is peculiar and indicates that
the conditions of their production are exceptional. One
moraine may show a well-formed bowlder belt, while its neigh-
bors parallel with it in front and behind have none. The diverse
composition of the bowlders seems also to be against the idea
of concentrated bowlder trains. In short, it would seem that we
must look much nearer than Canada for the cause of their very
local concentration. The only local cause that seems available
grows out of the relation of the readvancing ice-front to power-
ful lines of drainage at or near the edge of the ice. If, during
the building of a terminal moraine, a powerful stream of water
sweeps past the front of the ice so as to carry away the finer
material the bowlders may be left on the surface in greater num
bers than usual. Several of the well-known abandoned outlets
have more or less of this appearance. But where this is the
whole process the bowlders remain in a low position with respect
to the surrounding lands. If, however, a readvance of the ice

*“ Bowlder Belts Distinguished from Bowlder Trains—their Origin and Signifi-
cance,” by T. C. CHAMBERLIN. Bull. G. S. A., Vol. I, 1890, pp. 27-31.

440 FRANK BURSLEY TAYLOR

takes place the bowlders in the channel may be gathered up and
transported some distance and finally be deposited on or in a
rugged hilly moraine even to its topmost parts. In being car-
ried forward the bowlders may be more or less dispersed, or
they may be concentrated, or neither of these effects may appear.
In each case it depends mainly upon the relation of the river

Maumee
Lake

Decatur B

Fic. 3. Showing relation of the Whitley bowlder belt to the Wabash-Erie channel.

channel to the direction of ice-motion. If the channel were
straight and also normal to the ice-front the readvancing ice
would carry the bowlders all forward down the channel and con-
centrate them in a pile where it stopped. If the channel lay
athwart a pointed ice-tongue and close in front of it, the read-
vance would disperse the bowlders somewhat. There is a bowl-
der belt in Whitley and Huntington counties, Indiana, which
may be due to partial concentration by a readvance diagonally
across the bed of a great river corresponding to the stream that

MORAINES OF RECESSION 441

afterwards existed as the outlet of the glacial Maumee lake.
The accompanying sketch map shows the relation. Dryer and
Leverett show this belt on their maps."

The disposition of this belt seems to show that the ice-front
had retreated at least to Fort Wayne from the moraine next
west of the bowlder belt in Whitley county, and halted while
the large river excavated a channel about where the present old
outlet bed is between Fort Wayne and Huntington. Then by a
readvance the bowlders which had been left in this bed were car-
ried forward by the ice, which moved ina direction normal to
the ice-front, but diagonally across the river bed, and deposited
them in the Whitley morainic bowlder belt. If this took place,
then it is plain that the ice-front had retreated to Fort Wayne
and that it readvanced over more than half the space it had just
uncovered at the preceding retreat which was, therefore, not less
than thirty miles.’

This interpretation of the Whitley belt is not yet a sure
inference, for further and more particular investigation will be
required to fully verify or disprove it. The Montgomery-Ben-
ton county belts seem to be somewhat similarly related to a
readvance over a part of the Wabash River bed, and pos-
sibly to a former river bed about where Wild Cat Creek is
now, and the Iroquois belt may have had a similar relation to
the Tippecanoe River or to a glacial river that crossed from the
Kankakee to the Wabash farther west, but was obliterated by
the readvance.

DRYER in 18th Report of Indiana State Geologist, 1894, p. 84. LEVERETT in
the ‘“‘Inland Educator” (Terre Haute, Ind.), for August 1896, opposite p. 24. DRYER
shows only that part of the bowlder belt which lies in Whitley county; LEVERETT
shows it extending on southward nearly to Huntington. The accompanying sketch is
compiled from their maps.

2 The range or amplitude of oscillation may have been considerably more than
thirty miles. Indeed, after the ice-front left; Fort Wayne it must have been greater,
for the four intervals from this place to Port Huron are almost exactly fifty miles each.
The amplitude of oscillation was probably twice this or a little more — 100 miles or
over—if the Whitley bowlder belt can be relied upon to indicate a readvance from

Fort Wayne. The probable cause of the difference in amplitude east and west of
Fort Wayne will be discussed later on.

442 FRANK BURSLEV TAYLOR

On the whole, the character of the oscillation as one that
was always accompanied by a readvance after recession seems
to be well established by several different lines of evidence and
by several of the most experienced observers.

THE PROBABLE RATE OF ICE-SHEET MOTION.

The great ice-cap of Greenland bears a closer analogy to our
own Pleistocene ice-sheet than any other ice mass yet studied.
The observations of Peary, Chamberlin, Salisbury, and others
throw no uncertain light on the problems of ice-sheet motion as
there exhibited. On this point Professor Chamberlin says:

Lieutenant Peary has commenced a series of observations upon the
movements of glaciers of the Inglefield Gulf region, both by instruments and
by photographs taken at intervals. He found the daily movement of the
Bowdoin glacier, the most active in the immediate vicinity of his headquar-
ters, during the month of July to be four-tenths of a foot at the slowest point,
and 2.78 feet at the fastest point, near the center, with an average of 1.89
for the whole.*

The movement of the majority of the glaciers in that region is very
much slower; indeed, in most cases it is obviously exceedingly slow. Many
of the ordinary signs of movement are absent. In front of the Fan glacier
there are cones of granular ice brought down by the surface streams, and
also embankments of old snow, soiled, granulated, and half solidified into
ice, as though at least a year eld, all of which lie banked against the ter-
minal face of the glacier without any indication of movement on its part
since their formation. As these lean against the face to heights of thirty or
forty feet at least, it is obvious that there had been no melting of the base of
the extremity to counteract the effects of advance. Phenomena of similar
import were observed in several other glaciers. The very firm impression
was given by such physical signs that the average rate of movement of the
glaciers of the region is very slow. At the head of the gulf are a few
glaciers which produce large icebergs and which must be notable exceptions
to the prevailing slowness of motion.”

t According to Professor Chamberlin (JOUR. GEOL., Vol. V, No. 3, 1897, pp. 229-
232), the Bowdoin glacier is six or eight miles long, about two miles wide in its lower
part and descends between 2000 and 3000 feet. After its separation from the ice-cap
by a somewhat steep fall, the Bowdoin glacier becomes essentially Alpine in type.
Hence it does not furnish a criterion that can be applied to the ice-cap itself. Slow
as is the advance of the Bowdoin glacier, it is probably much faster than that of the
edge of the main ice-cap.

2 Recent Studies in Greenland, Bull. G.S. A., Vol. VI, 1895, pp. 216-217.

MORAINES OF RECESSION 443

Again, discussing glacial motion more broadly, Professor
Chamberlin says, referring to Greenland:

No average measurements, nor anything approaching to average meas-
urements, have been made. The high rates of movement of the Jacobshaven
glacier, as given by Helland, and of the Great Karajak glacier, as given by
Drygalski, and other similar measurements, are not at all questioned, but
these are quite exceptional, and almost as far as possible from being repre-
sentative. They exhibit extraordinary movements through deep constricted
straits, where the ice is forced by the vast accumulations of great areas in
the rear, and where the warm season appears to exert its earliest and great-
est effects. The amount of ice discharged in the form of bergs from these
two glaciers is very much greater than from any other known points on the
ice-front of Greenland. It is perfectly obvious that the average border of
the Greenland ice-sheet does not move at a rate even distantly approximat-
ing that of these two straits. If it did so, the whole coast of Greenland must
be overwhelmed almost immediately, because the competency of the summer
heat of that region to hold back the edge of the ice by melting is very
slight. Drygalski estimated the annual surface melting at seven feet. Even
this is much greater than the annual surface melting of the Inglefield Gulf
region, judged by that of 1894. While estimates are few, and even these
may need much qualification, it is nevertheless certain that the average
movement of that portion of the border of the Greenland ice-cap which lies
upon the land is extremely small. Of that portion which ends in the sea
only a small fraction has a high rate of motion, as is shown by the lack of
activity in the discharge of icebergs. When it is considered that the land
border is very much greater than the sea border, and that of the sea border
a portion has a relatively slow movement, it will be evident that the average
rate of movement for the border of the great ice-sheet of Greenland cannot
be high; and the average rate of this border is the nearest available
analogue to the border movement of the still more extended periphery of
the ancient American or Laurentide glacier.*

There can hardly be a doubt of the great value of the Green-
land observations in their bearing on the conditions attending
the Laurentide glacier that invaded the United States. It will
be observed that most of the measured rates of motion reported
by Peary, Chamberlin, and Salisbury are of ice tongues flowing
out a few miles from the main cap down valleys generally

*The Glacial Lake Agassiz, by WARREN UPHAM. Monograph XXV, U. S.

Geol. Survey, 1896. Topic entitled ‘Alternative Interpretations,’ by T. C. CHAM-
BERLIN, pp. 248-249.

444 FRANK BURSLEY TAYLOR

steep. None of the measurements are of a broad lobate front
such as any one of our great lobes presented south of the lake
basins. One would expect the rate of motion to be still slower
where it was evenly distributed along a broad front.

There is another character of the borders of the Greenland
ice that is a valuable aid in interpreting rates of motion. In all
glaciers that move at a relatively rapid rate, as is the case with
most Alpine, and fiord, or berg-producing tongues, the ice is
cracked and broken deeply, and shows a rough, tempestuous
surface with crevasses more or less numerous and deep. Slowly
moving glaciers do not show much of this character, but are
comparatively solid and smooth down to their ends, and this is
the character of nearly all the glaciers that end on land as
described and shown in photographic illustrations by Chamber-
lin and Salisbury."

There is a circumstance connected with some of the moraines
in the Cincinnati-Mackinac series which seems to leave little
doubt of the slow motion in the great ice-lobes that made them.
According to Professor Dryer the front of the Erie ice-lobe at
Defiance, Ohio, stood in about sixty feet of water, that being
the deepest point of Maumee Lake. But since the recent rec-
ognition of the low, faint, water-laid moraines it is found that
the front of the ice halted successively at Toledo, Detroit, and
Port Huron, in each case standing in about 200 feet of water.
The points mentioned mark the apex of the lobe at each halt,
and the place of the water-laid moraines and their land-laid
extensions seem to show that the ice fitted itself to the valley
relief in each case almost as perfectly as it would have done if
the water had not been present. This fact throws much valu-
able light on the condition of the ice when it stood in these
positions. Baldwin, Upham, and others have supposed from

*Glacial Studies in Greenland, by T.C. CHAMBERLIN, JouR. GEOL., Vol. II, Nos. 7
and 8, 1894; Vol. III, Nos. 1, 2, 4, 5, 6, and 7, 1895; Vol. IV, No. 5, 1896. Recent
Glacial Studies in Greenland, Bull. G. S. A., Vol. VI, 1895.

The Greenland Expedition of 1895, by R. D. SALISBURY, JouR. GEOL., Vol. III,

No. 8, 1895; Salient Points Concerning the Glacial Geology of North Greenland,
Jour. GEOL., Vol. IV, No.7, 1896.

MORAINES OF RECESSION 445

certain evidence they have adduced that lobes ending in glacial
lakes broke up like calving fiord tongues and floated away so
rapidly as to make their fronts concave.'’ Chamberlin seems to
show this effect by two moraines in the basin of Lake Agassiz
on his map in Geikie’s Great Ice Age, 1894 (opposite page 727).
Whatever the facts may be for the Lake Agassiz basin, this was
certainly not the case with the Huron-Erie lobe. The fact that
the ice was able to keep its place in 200 feet of water almost as
though no water were present shows (1) that it was not broken
and deeply crevassed into loose blocks that might easily float
away, but was comparatively solid and compact, proving (2)
that its motion must have been of the slow order rather than
of the rapid; (3) that its thickness at the edge as it then
existed must have been considerably more than 200 feet, prob-
ably not less than 300 or 400 feet ; (4) that although the front
must have been undercut and broken off to some extent by wave
action, flotation, and melting in the lake water, this process did
not become a factor of sufficient importance to seriously
disturb the line of the ice-front as determined by land relief
alone. The Saginaw lobe shows the same ability to conform to
the land relief while standing in water at the Saginaw moraine
over 150 feet deep.? I am led to believe, therefore, tentatively,
that the motion of the ice-sheet while building the moraines of
recession was very slow. That is, it was so slow that the lobes
as they crept along remained essentially solid to their extreme
edges.

*Glacial Lake Agassiz, Monograph, by WARREN UPHAM, Plates XVII and XIX.

Pleistocene History of the Champlain Valley, by S. P. BALDWIN, Am. Geol., Vol. XIII
March 1894, p. 181.

?Nansen, in his “ Farthest North,” Vol. II, p. 339, describes a glacier-front of
this kind in Franz Josef Land in the following terms: ‘‘ We were soon underneath
the glacier, and had to lower our sail and paddle westward along the wall of ice,
which was from fifty to sixty feet in height, and on which a landing was impossible.
It seemed as if there must be little movement in this glacier; the water had eaten its
way deep underneath it at the foot, and there was no noise of falling fragments or
the cracking of crevasses to be heard, as there generally is with large glaciers. It was
also quite even on the top, and no crevasses were to be seen. Up the entire height
of the wall there was stratification, which was unusually marked.”

446 FRANK BURSLEY TAYLOR

There are some writers who make the whole period of gla-
ciation very short. Mr. Upham believes that Lake Agassiz
‘‘endured only a thousand years or less,’ and he allows ‘“‘only a
few (perhaps four or five) thousand years” for the entire glacial
retreat, including the whole Champlain period of submergence
and most of the later reélevation of the land.t But it seems to
me that both fact and theory as they stand today clearly incline
toward a long rather than a short time.”

TRANSPORTATION AND DEPOSITION OF ENGLACIAL DRIFT.

If we turn to the best available evidence bearing on the
manner and rate of drift transportation by the ice-sheet we meet
with facts tending to the same general conclusion, viz., that
the building of the moraines was a very slow process. ‘The rate
of glacial motion is necessarily a function of the rate of drift
deposition. If it is sufficiently clear that the ice motion was very
slow we have that much gained towards a determination of the
probable rate of moraine building. The other function is the
drift load, and we have now to consider what evidence can be
brought to bear upon it and also what theoretical considerations
indicate as the probable truth.

Here again the Greenland ice-sheet is the closest available
analogue and the significance of its indications relating to drift
load and deposition are well set forth by Professor Chamberlin.
On these points he writes as follows:

That considerable débris is borne in the basal portion of the ice is not

questioned ; indeed, the term, “‘englacial drift’”’ was proposed by the present
writer in recognition of its importance. Our best evidence of the amount

™ View of the Ice age as two Epochs, the Glacial and Champlain.” Proc. A. A.
A.S., Vol. XLIV, 1895, p. 144. Also Am. Geol., XVI, August 1895, p. 107. For
duration of Lake Agassiz see also “Glacial Lake Agassiz,” by WARREN UPHAM.
Monograph, pp. 241-242.

2 Instudying the history of such a glacier as the Muir of Alaska with its relatively
rapid advances and retreats (“Glacier Bay and its Glaciers,” by H. F. REID, 16th Ann,
Rept. U. S. Geol. Survey ; map opposite page 454), and like many of those that calve
icebergs in Greenland, it must be remembered that the conditions of their motion are
not at all like those of an ice-sheet and that they do not furnish safe criteria for inter-
preting ice-sheet motion.

MORAINES OF RECESSION 447

and distribution of this is derived from the continental glacier of Greenland.
It is there observed that débris prevails in the lower 50 or 75 feet of the
ice-sheet, and occasionally reaches up to 100, or perhaps even 150 feet. The
amount of this débris, if it were let down directly upon the glacier’s bottom by
melting in situ without concentration by ihe forward motion of the ice, would
be measured by a very few feet, or by a fraction of a foot. The forward
motion of the ice concentrates this at its edge, so that it may there reach, theo-
retically, any dimension, entirely without regard to its amount in any given
vertical section of the ice. The thickness of the deposit formed from the
englacial drift is quite as much dependent upon the length of time during
which the edge of the ice remains at one line as upon the amount of drift
which the ice may carry in any given vertical section. No safe inferences
from the thickness of deposits of englacial drift can therefore be drawn with
reference to the amount of englacial material present in any given portion of
the glacier. If the ice were absolutely stagnant the deposit of englacial drift
would be precisely that which was held in the ice above the point of deposit.
If there was any forward motion of the ice while it was being melted away,
there would necessarily be a concentration. If there be one foot of englacial
débris in a given section and the ice moves forward 4o feet while the external
heat causes a retreat of 1 foot, the englacial deposit should be 4o feet deep.
The thickness of the englacial drift may therefore be quite as much an expres-
sion of prolonged time as of a large content of débris within the ice.

Referring to the manner in which the englacial débris becomes
at length exposed and deposited Professor Chamberlin, contin-
uing on the next page, says:

Instead of rising toward the surface of the glacier, it is believed, on the basis
of observations in Greenland, to pursue a course nearly parallel to the base,
on the whole, and to come out at the extremity of the glacier. To some slight
extent it may become superglacial by ablation, but only to a limited degree.:

Again, describing more specifically the phenomena in Green-
land, Professor Chamberlin says:

The débris belts are essentially parallel to the base of the glacier. They
are chiefly confined to the lower 50 or 75 feet; sometimes they prevail up to
1oo feet and rarely beyond. I think 150 feet might be named as a rather
extreme limit. They are more abundant at the sides of the lobes than at the
center, a fact that is significant in indicating the introduction of a notable
part of the débris after the lobes were formed. In consonance with this the
débris appears to be most abundant in the glacier-lobes which descend as
cataracts or crowd between closely hugging cliffs. If, standing in front of a

** Glacial Lake Agassiz,” Monograph, pp. 249 and 250.

448 FPRANIG BURSEBY TAYLOR

glacial lobe, the dirt bands are traced, many will be found disappearing at the
cataracts, or the embossments of the bottom, or at the spurs on the sides.

The general impression produced by such conclusions as these
is that an ice-sheet probably carries somewhat less englacial drift
than the tongues that, like those of Greenland so far described,
branch off from the main sheet and descend several miles and
2000 or 3000 feet down ravines or constricted valleys. The
tongues certainly have better opportunities to gather débris than
the bottom layers of the main cap. And the force of this
impression is greatly increased when we think of an ice-cap that
deployed over so smooth a plain as did, for the most part, the
Laurentide glacier in the area here considered.

Mr. Upham inclines to the opinion that ‘‘englacial drift was
carried up through the lower quarter or third part of the ice-
sheet, where, as in Manitoba, it was probably a mile thick.”
But, as Professor Chamberlin has said, there seems to be no
reason to suppose that the thickness of the bottom débris-
laden layers bears a fixed ratio to the total thickness of the
ice. Indeed, from the very fact that the upper part of a glacier
moves forward faster than its lower layers, it follows that the
bottom layers cannot rise beyond a very limited extent, except
by overthrust in consequence of flow over high points or emboss-
ments that project upward into the ice. In passing over high
obstructions high englacial drift may be introduced. But the
amount of such drift appears to be really insignificant, and it
even then becomes superglacial only after it has moved with the
ice far enough forward into the peripheral zone of ablation
to have had all the ice that overlies it melted off, or until it
reaches the very edge and is thrust upward over a moraine or
other obstruction.

Those who have not seen glaciers have often been much

*“ Recent Glacial Studies in Greenland,” Bull. G.S. A., Vol. VI, 1895, page 205.
Contrast with these ideas the opinion of Mr. UPHAM, where he says, speaking of the
great Leaf Hills moraine in Minnesota, that “perhaps not more than fifty or even
twenty-five years [were occupied] for amassing these morainic hills 100 to 350 feet

high on a belt 3 to 5 miles wide!” (‘Glacial Lake Agassiz,’ Mon., p. 242).
2“ Sublacustrine Till,” W. UPHAM, Am. Geol., Vol. XVII, June 1896, pp. 374-375-

MORAINES OF RECESSION 449

deceived as to the amount of englacial drift by the highly
deceptive appearance of pictures of débris-laden, melting ice-
tongues. Chamberlin and Salisbury both draw attention
repeatedly to the effect of the spreading of fine dirt so as to
blacken the whole ice wall. When small streams of clear water
wash this away, or the dark surface has been removed with a
pick, comparatively clear ice is seen beneath, and yet some of
these layers or thin lamine which they contain, may be the very
ones that were supplying the blackening material. Large masses
of englacial drift are rare and their forward motion is extremely
slow, certainly much slower than that of the clean ice above,
except where they occur, still more rarely, as lenses relatively
high up in the glacier so as to have a considerable thickness of
clear ice beneath them. In short, it seems to be shown that
englacial drift is a far less voluminous constituent of ice-sheets
than has been supposed by many. It keeps its importance, how-
ever, as almost the only means of drift transportation by conti-
nental glaciers like that which invaded the United States. But
except under peculiar circumstances the amount in any given
section of ice is almost insignificant. When all the circum-
stances are taken into account it seems probable that the load
of débris is as great or greater in the Greenland tongues than it
was in the Laurentide lobes in Ohio and Michigan. The coast
of Greenland is mountainous. The ice flows out among many
nunataks and along the base of high cliffs, and no doubt over-
rides many knobs and peaks and precipices from all of which
it gathers material in such a way as favors its becoming super-
glacial or englacial. Then, too, the exceedingly rough country
is favorable to the production of high overthrusts by which the
bottom layers with their débris may assume relatively elevated
positions in the ice.

When the ice-front was in Ohio or Michigan there was no
chance for the formation of lateral moraines from cliff-fallings,
nor of medial moraines from the detritus of nunataks. At that
stage of glaciation the field of ice stretched away to the north-
northeast without a break, and no land was exposed back of the

450 LEM RAINIKE EHIME SILIG IE ICAI VAL OU

edge. In Canada some of the path of the ice was rather rough,
but not in any sense comparable in this respect with most of the
coast of Greenland, and it was all deeply overridden at the time
the ice reached across Lake Huron to points farther south. It
follows that substantially all the northern drift of Michigan,
Ohio, Indiana and Illinois was carried forward from Canada
englacially. But the larger portion of the drift south of the
lakes is of local origin, derived from rocks near by. This region,
as the last ice-sheet found it, was probably a comparatively
smooth drift plain, made so by earlier Pleistocene ice-sheets
Almost the only way that local débris could become englacial
was by being taken up, absorbed or incorporated directly into
the lower layers of the ice as the glacier moved along. Under
the great pressure of ice, hundreds or perhaps thousands of feet
deep, this process must have become more or less effective. It
seems almost certain that substantially all the drift south of the
lakes was transported englacially, and in only the lower layers
of the ice-sheet. The maximum load which can be carried in
the bottom layers of the ice without overthrust cannot exceed
a certain amount for a given pressure and rate of glacial flow,
and that amount is probably not large. When the bottom lay-
ers become overloaded they clog beneath the ice and cease to
move, while the cleaner upper ice forms a plane of shear above
the clogged layers and overrides them. Professor Salisbury,
writing of the glaciers of Greenland, says:

Professor Russell has called attention to the fact that the movement of
ice is influenced by the amount of débris which it carries. This doctrine finds
abundant confirmation in the north. The lower part of the ice, which is well
charged with débris, or altogether full of it, seems to virtually lose its motion
and to become the bed over which the upper ice passes. It is not possible
to say that its motion is absolutely lost, but many phenomena seem to make
it certain that the upper portion of the ice of a glacier passes over the lower
débris-charged portion in the same way that it passes over a rock bed. The
lower part of the ice in such cases becomes virtually an ice conglomerate, the
mobility of which is certainly slight.’

r« Salient Points Concerning the Glacial Geology of North Greenland,” by R
D. SALISBURY. JOUR. GEOL., Vol. IV, No. 7, pp. 800-801.

MORAINES OF RECESSION 451

It appears to be a plain inference, even in the case of the
extremely slow motion of the Greenland cap, that however
slowly the upper layers of the ice move, the débris-laden bottom
layers move still more slowly. Even in a fiord tongue which
moves 50 or 100 feet a day, if the ice is 1000 to 1500 feet or
more deep the extreme bottom layers may move quite slowly.

The principles involved in basal clogging have been well
brought out by Professor I. C. Russell. He reduces them to
this proposition: ‘The rate of flow of glacial ice, under given
conditions, will depend upon the percentage of débris com-
mingled with it, and be least where the percentage is greatest.
For our present purpose this law may be advantageously restated

Be a

in terms of drift transportation and deposition rather than ice-
motion, thus: Whether the basal layers of a glacier will absorb
or deposit débris at a given place or pass over without doing
either, depends on their carrying an underload, an overload, or
just an even full load at the existing velocity and pressure.

Under deep ice, however, the building up of ridges or promi-
nences like terminal moraines, by the clogging of débris-laden
bottom layers, would seem to be impossible, because the tendency
there is to wear down and abrade every prominence of the land
that is overridden. Clogging under deep ice probably occurs to
some extent, but only by the shearing off of thin bottom layers
which do not remain as subglacial prominences. Hollows of the
land surface would tend to be filled up by clogging, and a mass
of débris once dropped in such a place would tend to stay there
unless the peculiar and rare conditions which lead the ice to
scoop out basins came into play. While the general truth of
Professor Russell’s proposition is plain, and the principle stated
is one of great value, it may be doubted whether it can have such
a function as he supposes when he suggests that it was the deter-
mining cause of the moraines of recession and their peculiar
distribution.?

t“The Influence of Débris on the Flow of Glaciers.” Jour. GEOL., Vol. III,
No. 7, pp. 823-832.

In a footnote to his article (page 831) Professor Russell makes the following

452 FRANK BURSLEY TAYLOR

The great Malaspina glacier of Alaska, so well described by
Professor Russell, belongs to the Piedmont type, and is probably

suggestion: “That a series of terminal moraines in a formerly glaciated valley, or a
similar succession of ridges left by a continental glacier, are not necessarily evidence
of repeated climatic oscillations, but may have been formed during a uniform and
continuous meteorological change favorable to glacial recession. ‘That is, a débris-
charged glacier may retreat for a time, then halt and again retreat, owing to its termi-
nus becoming congested with foreign material, in response to a climatic change which
would cause a glacier composed of clear ice to recede continuously and without halts.”

It is hard to see how clogging of the lower layers could have the effect of build-
ing a ridge like a terminal moraine anywhere except at or very near the edge of the
ice-sheet; and it seems certain also that the building of a great moraine must have
required a relatively long duration of time—much longer than the building of the
flat intermorainic plains of till. But under a uniform change of climate, as supposed
by Professor Russell, it seems impossible to allow much more time for the building of
a moraine than would be taken by a clear-ice glacier to retreat over an interval equal
to the width of the moraine unless the formation of the moraine is supposed to begin
under deep ice far back—at least several miles back —from the edge of the lobe.
When the front of the Maumee ice lobe was at Fort Wayne the ice was probably 400
or 500 feet thick within a mile or two back from the edge, and its thickness increased
to the northeast. From Fort Wayne to Port Huron there are five moraines in series
with four intervals of about fifty miles each, and with wide till plains intervening.
When the ice-front was just east of the Fort Wayne moraine, did basal clogging begin
then at Defiance, forty-five miles back under the deep ice, or did the ice-front retreat
from Fort Wayne to Defiance without clogging only to begin it again at the latter
place? If the former, then we must set aside the law of heavy abrasion on subglacial
prominences under deepice. Ifthe latter, then, as already pointed out, the time allotted
for the building of the moraine is little if any longer than that which would be taken
by a clear-ice glacier to retreat over a distance equal to the width of the moraine.

The Port Huron-Saginaw moraine is clearly traceable as a distinct individual
from the highlands south of Georgian Bay, where it is about 1000 feet above the
lake, descending to lake level at Port Huron, rising thence 300 feet to Ubly on the
“thumb” of Michigan, descending again to lake level at Saginaw, rising again
towards the northeast to the Au Sable River, and thence northwest nearly as far as
Petoskey, where it is again about 1000 feet above the lake—a distance of over 400
miles. It seems hard to account for such a moraine by clogging alone, and fora
series of them, the existence of which is a matter of simple inference from the facts
now at hand, the difficulty becomes much greater. Speaking of the terminal moraines
of the United States, Professor Chamberlin says: ‘‘Some of these have been traced
several hundred miles in individual distinctness, and, by fair correlation, may be
assumed to have been identified for a thousand miles or more.” (GEIKIE’s “ Great
Ice Age,” 1894. p. 740.)

But even if basal clogging in itself could produce moraines, that process taken
alone could hardly be the cause of such a marked and widespread periodicity in the
phenomena. The continuity and great length of individual moraines shows that the
periodic rhythm of the oscillations affected wide areas ; indeed, there lacks but little to

MORAINES OF RECESSION 453

the best modern example of it." But this glacier is the dump-
ing ground of hundreds of Alpine glaciers of the most pro-
nounced type, all descending steep, short slopes from high
mountains, and carrying heavy loads of débris—superglacial
loads as medial and marginal moraines, as well as heavy engla-
cial loads in their bottom layers. Contrasted with this the Lau-
rentide glacier had no Alpine feeders whatever. Substantially
all that it accomplished in the transportation and deposition of
drift was done by its bottom layers in englacial fashion. The
Malaspina apparently suggests nothing that would controvert
the general conclusions drawn from other sources. For its most
characteristic features are exceptional, and obviously do not
apply to the Laurentide ice-sheet nor to ice-sheets in general.’

THE PROBABLE DURATION OF THE PERIODS OF GLACIAL
OSCILLATION.

A little examination will show that no short period, such as
35, 100, or even 300 years will suffice for the building of the
moraines. From Fort Wayne to Port Huron there are five
moraines with four intervals of almost exactly fifty miles each.
These constitute perhaps the simplest group in the whole moraine
series. They have the widest and most regular intervals and
some of them, when not too deeply water-laid, are the very best
types of the structure characterizing deposition at a climax of
readvance. The intervals are so wide, and the valleys in which

prove that it was of continental extent. From present indications it would seem
almost certain that future investigations will establish this as a fact. But even sup-
posing moraines to be formed sometimes by basal clogging, what could be the cause
of such widespread periodic clogging if not climate ?

rMt. St. Elias and its Glaciers,” Am. Jour. Sci., Vol. XLIII, March 1892, pp.
169-182; ‘‘ Malaspina Glacier,” Jour. GEOL., Vol. I, No. 3, pp. 219-245.

?Mr. Upham has recently enlarged and elaborated Professor Russell’s suggestion,
but apparently without throwing any new light on the obscure processes involved.
(Am. Geol., Vol. XIX, June 1897.) He also endeavors to enforce the Malaspina
glacier, which is a perfect example of the Piedmont type, as a criterion for interpret-
ing the Laurentide ice-sheet or continental glacier. In this effort he even goes so far
as to call the Malaspina glacier an ice-sheet—an application of the term which is
clearly erroneous and misleading.

AS4 FRANK BURSLEY TAYLOR

the broad Huron and later Erie-Huron ice-lobes advanced are so
wide and smooth that the circumstances favoring simplicity were
at a maximum.

Suppose it took the ice-front thirty-five years to retreat from
the Fort Wayne to the Defiance moraine, receding at a uniform
rate. That would be a little over twenty and a half feet a day.
But this allows no time for retreat beyond Defiance, nor for the
halt at the warm climax of retreat and the building of a moraine
there of equal magnitude with that now seen at Defiance, nor
for the readvance to Defiance, nor finally for the building of
the Defiance moraine. If the Defiance moraine was built after
a readvance and if the nature of the oscillation was such as
shown in Fig. 1, then the time taken for the retreat from Fort
Wayne to Defiance must have been only a fraction of the whole
period of oscillation. We may measure the period of oscilla-
tion between the crests of the moraines, including always the
destroyed moraine of the warm climax. We may assume further
that the readvance is at least half of the previous retreat, and in
this case the moraine of the warm climax next after the Fort
Wayne moraine would be built at some point near Toledo and
after it was finished the ice-front would readvance to Defiance.
Then the first half of the period of oscillation would be measured
between the crests of the Fort Wayne and Toledo moraines, and
the second half between the crests of the Toledo and Defiance
moraines. The two middle points of oscillation would then be
half way between Fort Wayne and Toledo and half way between
Toledo and Defiance. The first of these would be about at Defi-
ance. On this basis the retreat from the crest of the Fort Wayne
moraine to the middle point at Defiance would take one-fourth
of the time of the whole oscillation and this includes half of the
time of the building of the Fort Wayne moraine. On the basis
of thirty-five years for the whole, this one-fourth part would
occupy only about eight and three-fourths years, and surely half
of this time would have to be taken to build half of the Fort
Wayne moraine, and that would leave only four and three-eighths
years for the ice-front to retreat fifty miles. The rate of retreat

MORAINES OF RECESSION 455

would then average about 164 feet a day. And further, this
retreat would have to take place in the face of the continual
advance of the ice, so that the ice would have to melt back
probably considerably more than 164 feet a day. Sucha con-
clusion is manifestly absurd and its absurdity is only increased
when we reflect that this is the average per day for the whole
year. During the winter months there must have been not only
no great amount of melting, but more or less readvance because
melting ceased; and it is probably true that for some months in
the spring and fall the forces of advance and retreat were about
at a balance. Only for three or four months in summer would
the forces of retreat be effective, so that substantially the whole
annual retreat would have to take place during the summer and
the rate of retreat would have to be at least four or five times
the daily average for the whole year, or 700 or 800 feet or more
per day. It does not help the matter much to change the period
to 100 or even 300 years. For it would still be necessary to
postulate a high rate of retreat—seventy or eighty feet per day
during the effective melting season. If the period were 3000
years the rate would still be seven or eight feet a day at that
season. With the period at 6000 years the rate would be three
and a half to four feet a day, and at 12,000 years one and three-
fourths to two feet a day.

We may suppose, if we choose, that at every turn of retreat
the ice-sheet became completely disintegrated and broken up, at
least over a wide marginal belt, on account of the suddenness
and intensity of the increased warmth. But such a supposition
savors of catastrophism and does not seem to be in the line of
probable truth. The equilibrium between glacial accumulation
and ablation must have been a very delicate one. There could
be no wide departure from a balance of forces without a corre-
sponding great change in the extent of the ice-sheet. Surely the
climatic conditions which permitted the ice-front to stand fora
long time at Fort Wayne were not greatly different from those
that permitted it to stand at Defiance or at Toledo. There is no
need of supposing that sudden or violent climatic changes produced

450 JMKOAINIS Sake SVLII NA ICA VOLO

the oscillations. There is nothing inthe phenomena of the drift
that requires it, nor has anything been discovered in the behavior
of the Greenland ice-sheet that suggests it. The summers were
seasons of melting during the phase of advance as well as during
that of retreat, and it may be doubted whether the most skillful
observer could have detected any difference in the summers of
the two phases unless he had made the most refined gauge
measurements on the volume of the water discharged. Whether
the ice-front would advance a little or recede a little or remain
stationary during a long period of years was a matter of the
utmost delicacy of adjustment. I doubt whether the average
annual temperature for a period of years need differ more than
two or three degrees to determine whether the ice-front shall
stand at Fort Wayne or at Defiance.

Again, there seems every reason to suppose that the general
advance of the ice-sheet was after the same manner as the retreat,
only that the oscillations were reversed, and that it required
the same duration of time. From the halt at Defiance the ice
would retreat to Toledo, and then readvance to Fort Wayne, and
so on. If this is a true assumption, then it would require us to
suppose that the ice-sheet must be able to advance from Toledo
to Fort Wayne in the same time, and hence at the same rate, as
it is supposed to retreat over the same interval during the gen-
eral recession. But it is manifestly impossible to suppose that
the ice advanced at a rate of anything like 1000 or even 100 feet
aday. The great wide lobe that advanced up the Maumee valley
isnot to be compared with the Muir, or the Karajak glacier, but
rather with some part of the Greenland ice-cap that ends on
land. It was not breaking off and floating away as bergs. It
seems certain that its motion must have been very slow, probably
not over two to five feet a day, even at the maximum.

But if it seems necessary to put the period of oscillation at
3000 years or more, it becomes a matter of comparatively small
importance whether it bea little more or less. We have no means
of knowing just what it was, but if 3000 years seems to be an
extreme minimum and 6000 years seems better, there is no pos-

MORAINES OF RECESSION 457

sibility of drawing the line just there and saying that it could not
have been 10,000 years or even more. At the present day the
combined weight of the facts, theories and analogies available
to us seems to me to lean toward the conclusion that an oscil-
lation period of between 5000 and 10,000 years would be the
most satisfactory. If we take the Fort Wayne moraine to be
five miles wide and the period of oscillation to be 5000 years,
and if we suppose the period to be divided in two halves equal
in time, one of advance to Fort Wayne over a space of fifty
miles and the other of retreat from Fort Wayne over a space of
100 miles, then we may say in round numbers that it took 700
or 800 years to build the Fort Wayne moraine. If we take the
period of oscillation to be 10,000 years, then it took twice as
long.

THE SUPERPOSITION OF THE OSCILLATIONS UPON A GREATER AND
MUCH SLOWER CLIMATIC VARIATION.

That there was a periodic oscillation of the ice-front of some
kind or other needs no better proof than the simple fact of the
existence of the moraine series itself. We have seen that by its
influence upon climate precession would tend to produce a to and
fro oscillation of the ice-front. We have seen also that there
is a considerable amount of reliable evidence showing that the
oscillations which took place did, in fact, have the character
ascribed to precession. But if terrestrial climate had suffered no
change from any other cause than that which produced the oscil-
lations, then the ice-front would have gone on playing back and
forth for an indefinite time over the same narrow strip of ground.
But the moraines are distributed in a great series from south to
north with intervals between them that are remarkable for their
regularity, when due allowance is made for the influence of
topography. This arrangement seems to be explicable only on
the supposition that besides the oscillations there was another
greater, slower change of climate in progress—many times
longer in duration than the period of oscillation. Whatever
their cause, the oscillations were obviously superposed upon this

458 FRANK BURSLEY TAYLOR

greater, slower climatic change. After the grand climax of
advance, when the ice of this epoch reached its farthest point
south, the long retreat began and the oscillations that made the
moraines of recession went on round after round during the slow
progress or the greater change. This is a truth that stands out
clearly on the face of the larger facts and is entirely independ-
ent of all theories as to the cause of the oscillations or of the
greater change itself. Here again the moraines of recession, by
their arrangement, and by the regularity of their intervals, help
us to a partial insight into the nature of this greater change —
the real cause of the Ice age. Not that they show us the whole
cause fully and clearly, for they donot. But they show us enough
of its real nature to enable us to eliminate several hypotheses
that have been suggested, and so to narrow the range of discus-
sion. The cause of the greater change must have been of an
astronomical nature, and there is apparently no alternative.

In order to see the full import of the facts we must see just
how the oscillation is related to the greater change. If the
oscillations were regular (either with equal time intervals, or
with time intervals that varied progressively at a uniform rate)
and the greater change also regular (uniform or varying at a
uniform rate) then the moraine series would tend to be regular,
but if either one or both of the changes were irregular, then
the moraine series would be irregular. To getaregular moraine
series out of a combination in which either factor was irregular
would be accidental, and an assumption that such a cause has
produced the moraine series would be gratuitous and without
reasonable foundation.

A careful analysis of the effect of topography in causing
irregularities in the moraine series seems to show that the inter-
morainic intervals are not uniform, but increase from south to
north. By reference to. the map it will be seen that from the
first moraine back to the ninth, or Fort Wayne moraine, the
intervals are shorter than from Fort Wayne northward. The
effect of topography can be best understood by considering the
glacier in its advancing phase.

MORAINES OF RECESSION 459

When the ice-front was at the Hagenville (15th) and Alcona
(14th) moraines, the apex of its lobe in the Huron basin was in
the present lake bed, and so cannot now be exactly located nor
measured. But at the next halt the ice-front stood at the Port
Huron-Saginaw moraine (13th). This is the first one now fully
recorded on land. At that halt the ice was held back by the high-
lands south of Georgian Bay in Ontario, and by those southeast of
Petoskey in Michigan, and it was also held back about fifty miles
by the “thumb” of Michigan. With further advances the separ-
ated Saginaw and Huron lobes moved forward nearly equally at
first, but soon the Saginaw lobe met higher ground, and slowed
its pace, while the Huron lobe moved on more rapidly and met
and blended with the Erie lobe coming up the Erie basin from
the northeast, and the two advanced as one lobe up the Maumee
valley. The ice clogged more and more against the high ground
in southeastern Michigan, and began the building of a great
interlobate moraine upon it. This obstructed the advance of the
Maumee lobe pretty effectually on the northwest side, while the
high ground along the south side of the Erie basin did not allow
of much expansion on that side either. Hence the advance was
mainly up the wide flat Maumee valley until Fort Wayne was
reached. At this point there came an important change. The
ice-front had almost reached the flat rim of the Erie basin along
that part of the front line which extends from Fort Wayne east-
ward about 140 miles, nearly to Mansfield, Ohio—to the east
side of the head of the Sciota valley. The subsequent advances
found ample room for expansion in the most advantageous way ;
that is, in a southerly direction and down grade. The ice soon
began advancing down the Wabash and White River valleys in
Indiana, and down the Miami and Sciota valleys in Ohio.
Besides, the Maumee lobe had now pushed so far ahead of the
Saginaw that the obstruction on its northwest side in Indiana had
been somewhat relieved. But before becoming distinctly segre-
gated into four sub-lobes, the ice advanced for a few steps very
evenly over the level summit plateau, forming the remarkably
regular and concentric series of moraines south of Fort Wayne

460 FRANK BURSLEY TAYLOR

and extending over into Ohio. At the sixth and fifth moraines
the ice-front began to push slightly forward down the Miami
valley, but the lobe did not become distinct until the fourth
moraine. From that to the first moraine the Miami lobe devel-
oped more and more individuality. The first four moraines mark
the fully developed lobe and the circumstances under which they
were made probably accounts for the smallness of two of their
intervals —eight and twelve miles between the second and third
and the third and fourth respectively. The Miami was the
smallest and narrowest of the four valleys and hence its ice-lobe
was more cramped than the others. Besides, there was no such
concentration of advance in the Miami valley as there had been
before in the Maumee. The pressure was relieved by the other
three lobes, while from Detroit and Cleveland to Fort Wayne
the large Erie-Huron lobe was cramped by highlands on its sides
and hence pushed forward in a comparatively long, sharp point.

In this discussion of the intervals we have followed the ice in
its advancing phase. We have only to reverse the order of
events to see that the influence of topography was substantially
the same during the retreat.

This, as it seems to me, is the true explanation of the varia-
tions of the intermorainic interval, and it indicates that the nar-
row intervals which prevail from the first to the ninth moraines
are not out of harmony with the wider intervals from the ninth
to the thirteenth. The shorter intervals of these moraines do
not indicate, as might be supposed, a radical difference in cli-
matic conditions, nor of amplitude of oscillation, nor, possibly,
of the rate of the general retreat, but mainly the influence of
topography.

If the moraines showed nothing further it would seem clear
that the rate of the main retreat had been perfectly uniform, or
at least very nearly so. But if we turn to northern Michigan
and compare the intervals of four moraines there with the four
south of Fort Wayne, an increase of the interval northward
seems to be suggested. South and southwest of Fort Wayne
four parallel moraines (the sixth to the ninth) lie within a space

MORAINES OF RECESSION 461

of forty-five miles. They were formed at the broad apex of the
Maumee lobe expanding ona nearly level plain. In the north
there are four parallel moraines (the twelfth to the fifteenth)
also in a space of forty-five miles on a line running southwest
from Rogers City past Gaylord. These moraines are banked up
against the northeast face of the highlands and mark a great
reéntrant angle of the ice-front. The fifteenth is 800 or goo feet
lower than the twelfth, while the ninth near Fort Wayne (on
a line running southwest from Paulding, Ohio) is only about 100
feet below the sixth. At present we have no measure of the
intervals in the north except on this steep slope. It seems plain,
however, that if these four moraines had been laid down ona
level plain without being banked up against the highlands the
normal interval would have been considerably greater than it is.
On the other hand, near Fort Wayne it seems clear that if the
highlands of northeastern Ohio and western Pennsylvania and
New York had been absent and a level plain there instead, so
that the expansion could have been distributed evenly along the
edge, the normal interval would have been somewhat less than
it is.

These facts seem to show that while the oscillations were
going on, probably at a substantially regular rate, the main
climatic amelioration and its resulting glacial retreat was also
going on, not uniformly, but at a progressively increasing rate.
From the first (or second) moraine near Cincinnati, where the
great advance of this epoch had stopped and the great retreat
begun, the ice-front retreated at first very slowly, but faster and
faster as the front receded northward. Here again the character
of the simple harmonic motion seems to be revealed as the
probable manner of the varying rate of retreat. And this gives
a decidedly astronomical quality to the cause. Whether the
cause was due to some greater variation like precession, or to
some slow orbital change, either of eccentricity or of magnitude
affecting the distance of the earth from the sun independently
of eccentricity, it may at least be said that any variation of cli-
mate that can be so represented must spring from a cause which

462 FRANK BURSEEVY TAYLOR

proceeds in a great curve, and if glacial epochs are periodic, as
they may be, then the variation is expressed by a closed curve,
either circular or elliptical.

The manner of retreat under such a combination of forces
may be represented graphically with approximate accuracy as
follows: Assuming the oscillation to be superposed upon a
greater amelioration having a uniform rate, the resulting path
would be an epicyclic curve. If the recession took the form of
retreats and halts without readvances the curve would come to a
point at the moraines as in Fig. 4, A, and the moraines would
have cross sections, under the simplest conditions of formation,
like that shown in the figure. With readvances the curve would
be a iooping epicycle as in Fig. 4, B, (a) and (6), and if the
readvances covered more than half of each preceding space of
retreat the loops would overlap as in Fig. 4, B, (c). In both free
and overlapping loops, the forms of the moraines would be as
shown in Fig. 1 at A, and in Fig. 4,B,andC. As we have seen,
this last appears to have been the actual manner of retreat, at
least in Ohio, Indiana, and Michigan. This is shown in Fig.
4, B, (c). Ifthe greater climatic variation is truly represented
by a simple harmonic motion, then the overlapping of the loops
was most extensive near Cincinnati, and decreased going north-
ward. This order of retreat is represented approximately by
Fig. 4,C. The facts seem to favor this method of interpretation
quite strongly, but it is not necessary to pursue the theoretical
aspect of the problem further here. It is suggested in this paper
that precession of the equinoxes may have been the cause of the
secondary climatic oscillations which produced the moraines of
recession. But no statement, nor even a definite Opinion, is
ventured as to the cause of the greater, primary variation of
climate which brought on the Ice age itself, except that it was
of an astronomical nature. It may be added, however, that the
astronomical theory of Croll even as modified and reénforced
by Ball, is thought not to afford an adequate or satisfactory
explanation. As to those other various hypotheses which pos-
tulate purely terrestrial causes, such as the displacement of the

MORAINES OF RECESSION 463

A= Gecrating Retreat without Readvances

ve of Climatic Oseriier,,
Laos Os YA
MN
NZ
7

: 8 by4 3
Moraine--- ---Cross-sections

Be Siccllatien with Readvances
(c) Overlappins ; (a)

| Moraine_

, | &-Sections
0 ee

Gi j G : G i O C C Oscillations of the

Ice-front

C— Oscillation Superposed on aGreater, S lowly-Accelerating Climatic Amelioration.
— of Climatic Ose sss

Sr

Fic. 4. Showing combinations of the period oscillation with the greater climatic
change.

464 FRANK BURSLEY TAYLOR

Gulf Stream by the submergence of the Isthmus of Panama or
by the elevation of a supposed Antillean continent, or those that
rely upon mere epeirogenic uplift in the north, they have no
sort of intelligible relation to the characters revealed by the
drift. In fact they appear to fall so far short of explaining
these characters that there seems to be no longer a hope of
gaining any real advantage from their consideration.

SUMMARY.

1. Between Cincinnati and Mackinac the Wisconsin drift
formation has fifteen terminal moraines which form a consecu-
tive series marking the retreat of the last ice-sheet; and there
are three more farther north probably belonging to the same
set. The series seems to be complete and is believed to con-
stitute the simplest and most perfect known.

2. Making due allowance for the influence of topography, it
appears that the intervals between the members of the series are
remarkably regular, suggesting periodic halts or oscillations of
the retreating ice-front, which appear to be attributable only to
a periodic change of climate. But, excepting the annual period
and a thirty-five-year period deduced by Forel and others
from glacial and meteorological observations, the only periodic
change of climate known is that due to the precession of the
equinoxes with a period averaging 21,000 years and a minimum
of 10,500.

3. A study of the forms of the moraines where they were
made under the simplest conditions shows that they were always
made at the climax of a readvance. In one instance at least
the readvance appears to have covered more than half of the
space of the previous retreat. Theoretically, the influence of
precession on climate would cause a to and fro oscillation of the
ice-front after the manner of a simple harmonic, and this super-
posed upon a greater and slower change, would produce an
oscillating retreat with minor periodic readvances. This appears
in fact to have been the manner of retreat during the formation
of the moraine series, for those formed under the simplest con-

MORAINES OF RECESSION 405

ditions have their crests forward; they have relatively short,
steep front slopes and long gentle back slopes.

4. In attempting to deduce a period of oscillation from the
study of existing things, the present ice-cap of Greenland was
taken as the closest analogue for interpreting the drift of the
Laurentide ice-sheet, and the chief reliance is placed in the
observations of Professors Chamberlin and Salisbury. From
these the conclusion is reached that the frontal edges of the
great ice lobes that made the moraines of recession moved only
very slowly, so slowly as to be in substantial accord with a
period of oscillation equal to the minimum value of the preces-
sional period. A period of between 5000 and 10,000 years,
however, would seem to accord most closely with the phe-
nomena. From Fort Wayne to Port Huron there are five
moraines with four intervals of about fifty miles each. On this
basis the Fort Wayne moraine with a width of five miles would
have required something between 700 and 1600 years for its
making.

5. The regularity of the oscillation and also of the greater
climatic change upon which it was superposed both point clearly
to astronomical causes. The periodic oscillation may have been
due to precession, but no opinion is ventured as to the cause of
the greater change. On this basis then, it took the ice-front
75,000 to 150,000 years to retreat from Cincinnati to Mackinac,
and the whole glacial epoch lasted at least 150,000 years and
possibly 300,000 or more. And if glacial epochs are periodic,
as they may possibly be, then this period is only a fraction of

the great cycle of climatic change.
FRANK BurRSLEY TAYLOR.

THE ERUPDIVES ROCKS OES Vi xaE@;

Part III of the recently published Bosguejo Geoldgico de
México consists of a study by Ezequiel Ordofiez of the eruptive
rocks of Mexico.t' This may be regarded as the most complete
and satisfactory summary of the present state of knowledge of
this subject which has yet been published.

Humboldt’s Essay on New Spain contains many observations
on the rocks of the silver-bearing regions of Mexico which
are made with great accuracy and fullness of detail. But the
science of petrography has made many advances since Hum-
boldt’s day. It is no longer sufficient to describe rocks as
primitive schists and porphyries nor can altered andesites and
tuffs be disposed of as graywackes. These terms are, however,
an improvement on sazum metalliferum, the name by which
many of the rocks were earlier known. Modern geologists,
moreover, can hardly agree with the great savant in his con-
clusion that the richness of veins is entirely independent of the
nature of the rocks which the veins traverse. The great sim-
ilarity found among the rocks of the silver-bearing regions of
Mexico and their resemblance to those of Nevada and Germany
in which similar veins occur, indicates that a definite relation
probably exists between rock and vein.

Humboldt’s work, however, remains about the only authori-
tative one on the rocks of Mexico as a whole, which can be
consulted. The names which he applied to the rocks and the
opinions which he expressed regarding their origin will be found
to be those prevailing in Mexico today. Since the publication
of his work studies of single rocks or of limited regions have
been published, but little, if any, attempt has been made to
correlate observations. There is room, therefore, for a compre-
hensive study of the kind made by Seftor Ordofiez.

t Boletinz del Institute Geoligico de México, Nums. 4, 5, y 6, Mexico, 1897.
466

THE EROPTIVE ROCKS OF MEXTCO 467

In his paper the rocks are described in terms of modern
petrography and with as much detail as the plan of the sketch
permits. This plan he states to be an endeavor to give some
idea of the petrographic provinces of the country, indicating
for each one of them the predominating species, without enter-
ing into minute details concerning the extent of each. Com-
mencing with the pre-Cretaceous rocks, the granites, pegmatites,
granulites, syenites, and dicrites of this age are described in
order in their respective provinces. The post-Cretaceous rocks
are discussed next, beginning with the granites and passing on
in order through the granulites, diorites, diabases, andesites,
dacites and rhyolites. Then are taken up what are called the
andesites of the second invasion, which were produced by the
volcanic eruptions which began near the end of the Tertiary
period. Finally the labradorites and basalts which largely
characterize the latest eruptions are considered. Of especial
interest is the account given of the rocks of the great silver-
bearing regions of Zacatecas, Guanajuato and Pachuca, regions
which though widely separated, the author finds to present
remarkable uniformity as to kinds of rock and circumstances
of outflow.

The work is marred by some errors, such as calling hyper-
sthene a monoclinic pyroxene (p. 264), and the indiscriminate
use of the terms amphibole and hornblende. The punctuation
and paragraphing also admit of much improvement. The char-
acter of the work is as a whole, however, so admirable, that I
have thought that to give a résumé of it by means of a transla-
tion of extracts would assure a wider circulation to some of the
facts enunciated by Sefior Ordonez than they would perhaps
otherwise attain. Of such extracts the remainder of this paper
is made up.

The first indication of the part of the American continent
which forms the country of Mexico, was given in Paleozoic
time by the emergence of a narrow, elongated backbone which
uniting with the beginnings of the Rocky. Mountains to the
north and of the Andes to the south constituted the foundation

468 OLIVER C. FARRINGTON

of the orographic system known as the Cordillera of the Andes
It is in the part of Mexico known by the name of the Western
Sierra Madre that.we may expect to find the principal types of
ancient eruptive rocks, associated as a rule with crystalline
schists and some of the earliest sedimentary rocks. The Sierra
Madre extends along the Pacific coast in a general southeast-
northwest direction. The western slopes, generally descending
rapidly to the coast, present a notable contrast to those of the
east, where numerous spurs or secondary sierras serve to support
the extensive plateau of the Mesa Central. It was along the
eastern slopes that the eruptive movements which in epochs
later than the Cretaceous added to the relief of the Sierra
Madre, chiefly occurred. Here may be seen the whole series of
modern eruptive rocks, from the granites with which the erup-
tions clearly began, to the basalts of Quaternary time.
Considering first, then, the pre-Cretaceous rocks, we find
them consisting chiefly of granites. These probably make up a
large part of the mountains along the western coast of the Penin-
sula of Lower California, but of their exact distribution we
know as yet little. In the region of Hermosillo, Sonora, in the
district of Moctezuma, granite, crossed by dikes of pegmatite,
occupies great tracts of country. Inthe district of Altar sye-
nites and diorites replace the granite. In the region south of
the state of Puebla in the districts of Chiautla and Matamoros
micaceous or amphibolic granites are found passing over to
gneiss or green schists. The granites are interrupted frequently
by modern eruptive rocks, chiefly rhyolites and andesites, or
even by stratified rocks, generally Cretaceous. In the state of
Jalisco in the canton of Mascota and along the slopes of the
Sierra toward the Pacific, the group of mountains of Desmoron-
ado is formed of granites associated with quartzites and other
metamorphic schists. In the central and western parts of the
state of Oaxaca may be seen an extensive formation of granites
and diorites, covered sometimes by breccias and modern quartz-
ose conglomerates. These ancient masses, chiefly granites, may
be followed, although interrupted by modern eruptive and sedi-

THE ERUPTIVE, ROCKS OF MEXICO 469

mentary rocks, nearly to the coast of the Pacific and the Isthmus
of Tehauntepec.

By far the larger number of the eruptive rocks of Mexico
_are, however, of post-Cretaceous origin. Among the rocks
which began this prolonged eruptive epoch, granites and granu-
lites predominate, syenites are rare, andesitic diorites are abun-
dant, and diabases sometimes occur. The different varieties,
however, pass from one to another by insensible gradations, and
frequently exhibit as well an ophitic or trachytic structure which
leads them to resemble the true porphyrites and andesites. The
frequent recurrence of these phenomena serves as a corroboration
of Iddings’ theory of the differentiation of magmas. The post-
Cretaceous eruptive rocks which approximate in structure most
nearly to those of pre-Cretaceous age, occur chiefly in the
central regions of the northern and northeastern portions of the
country, and are usually associated with Cretaceous limestones.
The granulitic structure is that which predominates, but it may
be modified to that of the granites, or even descend through the
micro-granulites to the orthophyres and rhyolites.

The rocks which come after the granites have usually been
known in Mexico as greenstones or green porphyries on account
of their characteristic color and porphyritic appearance. To
these rocks great interest has long been attached since they
lodge the most important metalliferous veins of the country. A
chart showing the mines of Mexico well indicates the distribu-
tion of these rocks. Each metalliferous district presents in the
mass of its rocks a similar series of eruptions, thus indicating a
certain contemporaneity and analogy of circumstances of out-
flow. The three types of rocks found in these districts in the
order of their appearance are: (a) andesites and green dacites,
(6) rhyolites, and (c) labradorites and basalts.

Those of the first type have already been referred to as
greenstones. They may also be described as andesitic porphy-
rites, chiefly of hornblende, and orthophyres, while some more
nearly resemble the amphibole and pyroxene-andesites. All
present similarities to the rocks described by von Richthofen

470 OLIVER 6 ATTKIN G DOWN,

under the general name of propylites, which are well known in
Hungary, Transylvania, Nevada, and from some South American
localities. They present various aspects of the trachytic and
trachyto-porphyritic structure, a different quantity and develop-
ment of the elements of the first generation sometimes caus-
ing the microlitic magma to predominate over the amorphous.
An idea of the various aspects which these rocks present can be
given by mentioning some from different localities. _Commenc-
ing with the dacitic types, one may note the rock which occurs
at various points in the mining district of Parral, in the state of
Chihuahua. It is dark green to dull green in color, and contains
scattered crystals of transparent feldspar, together with horn-
blende that to the naked eye appears to be of a dark green
color, and lamellz of dark green mica. The magma is of a
character in part microfelsitic and in part microlitic, with dis-
seminated particles of yellowish green hornblende, which is the
mineral which gives to the rock its color. The crystals of
hornblende are in part decomposed and do not always preserve
their sections. This alteration, either central or peripheral,
consists of a transformation to calcite, chlorite and sometimes
to epidote.

To judge by the free quartz which it sometimes contains,
this rock bears some similarity to the felso-dacites of propylitic
appearance, of Rosenbusch, and may correspond in part to the
dacites as well as to the porphyrites of Fouqué and Lévy that
are likewise analogous to some of the propylites described by
Zirkel from the Virginia Range. In the same region these
rocks sometimes have a lighter color owing to the abundance of
disseminated feldspar crystals which give a more marked _por-
phyritic appearance. There may also be observed with the
naked eye and in very variable quantity, grains of pyrite dis-
seminated in the paste.

In the region of Guanacevi, Durango, altered andesites of
green color form the rocks of the first eruption. With these are
associated superposed andesitic tuffs and sometimes rhyolitic
tuffs, likewise green, in beds of considerable thickness which

THE ERUPTIVE ROCKS OF MEXTCO 471

always contain veins of epidote visible in thin layers. The
greater number of the mineral veins of this locality occur in
these rocks. In the state of Sinaloa these greenstones abound
in many of the mining districts, but are more or less altered by
the contact of the metalliferous veins, now gold, now silver-
bearing. These microlitic greenstones pass sometimes to an
ophitic structure, and even to holocrystalline rocks of clearly
granitic structure giving types of diorites and diabases. In the
territory of Tepic green andesites occur in great quantity,
always with analogous characters. In the state of Jalisco green
dacites occur at the mines of Los Reyes, San Sebastian, and
Real Alto.

In Fresnillo and Sombrerete, in the state of Zacatecas, rocks
of similar aspect are found covered by an extensive formation
of rhyolite tuffs.*. In the district of La Luz, state of Guana-
juato, the small size of the mineral elements and the profound
alteration which the rocks have undergone prevents usually an
exact microscopic determination of the minerals or the rock
structures. It is, however, possible in some cases to observe
characters which show that the rocks approximate to andesitic
porphyrites or hornblende andesites.* It is interesting to note
that there exist great similarities between the rocks of La Luz
and those associated with the rhyolite tuffs in the mines of
the state of Zacatecas. The fine grain of the former rock has
indeed caused it to be called a rhyolite tuff.

As regards the age of the formations of La Luz and those
about the city of Guanajuato, various conclusions have been
reached, owing to the absence of fossil remains in the sediments,
as well as the complex nature of the eruptive regions of the
vicinity. The rocks of the latter regions, which include the
hornblende granites of Santa Ana and the granites of the Ser-

tThe rocks classified as rhyolite tuffs are some of them andesitic tuffs which
appeared during the eruptions of andesites, and were later impregnated with silica,
while others were derived from the eruptions of rhyolites.

?’'The term porphyrite is restricted in use by Ordonez, but is employed by him to
designate Tertiary rocks differing slightly in appearance from the common andesites
and showing peculiar alteration.

472 OLIVER C. FARRINGTON

rania del Gigante, belong undoubtedly to a pre-Cretaceous
epoch. Fragments of these granites, syenites, etc., occur in
the red conglomerate of Guanajuato. They are undoubtedly
anterior to the rocks of La Luz, which may be considered to be
recent Tertiary.

In the metalliferous regions of Pachuca, Real del Monte,
and El Chico, in the state of Hidalgo, altered pyroxene-ande-
sites and dacites of green, dark and light gray, and violet color,
constitute the predominating eruptive rocks. They are distin-
guished from the rocks previously cited chiefly by their struc-
ture, which may be considered as invariably trachyto-porphy-
ritic; a structure produced by large crystals of labradorite and
altered remains of crystals of pyroxene. Andesite tuffs like
those of Guanacevi or rhyolite tuffs like those of Zacatecas
scarcely occur at all. There are many other points along the
Sierra Madre where the andesitic greenstones occur, chiefly in
the states of Chihuahua, Sinaloa, Durango, Jalisco, and the ter-
ritory of Tepic. From these the regions of Zacatecas, Guana-
juato, and Pachuca are somewhat distinct from an orographic
point of view. Considered petrographically, however, they are
mountain regions which, on account of the order of eruption of
their igneous rocks, may be regarded as branches of the Sierra
Madre penetrating toward the interior.

Trachytes and trachyte-andesites have in some of the locali-
ties mentioned immediately succeeded the andesites, either as a
modification of the latter or as a later eruption. Trachytes
are, however, relatively rare in Mexico, especially .among the
earlier eruptives. They are more frequent before the second
period of andesites and in the modern eruptions.

The rhyolites appeared after the andesites, presenting the
variations common to rocks of this type. They occur in many
localities, only the principal ones of which can be indicated. In
the central part of the Sierra Madre the rhyolites cover great
areas. Here the structure passes from the micro-granulitic to one
entirely vitreous giving obsidians and retinites. The rhyolites
are likewise notably abundant in many places of the Mesa Cen-

RAE BROPTIVE ROCKS (OF MEXTCO 473

tral, where some of them may be considered of later age than
those of the Sierra Madre.

In general it can be said that the forms of the mountains
of rhyolites are always characteristic, serving in many cases to
foretell their nature, especially when this rock occurs alone in
an extensive portion of one serrania. Of those with sharp and
elongated peaks we have a good example in the peak of Bernal
in the state of Queretaro. The extended forms present us great
cliffs (acantilados) in the extensive serrania of Valdecanas and
in the no less interesting Sierra Fria in the state of Zacatecas.

In the second of these serranias, formed in great part of
rhyolites, variations of structure and texture have brought about
the formation of plateaus and dome-like summits and erosion
has given rise to broken, fantastic shapes. In this sierra as in
many other localities formed of the same rock, the spherulitic
rhyolites of slightly coherent or tufaceous paste alternate in-beds.
more or less horizontal or parallel with petrosiliceous rhyolites
charged with quartz, which are compact and resist the forces.
of erosion. The result is an appearance of steps or stairs at
different heights on the slopes of the mountains. The surfaces
of the separated blocks, as a result of contraction or atmospheric
action, generally have columnar or other imitative forms, such
as are shown by some of the peaks called The Friars; a name
by which rocks of columnar structure are designated in various
parts of the country.

As notably spherulitic rhyolites can be mentioned those of
Chichindaro, in the state of Guanajuato, and those of San
Ildefonso, Tula, Hidalgo. There are spherulitic and _perlitic
retinites in Apaseo el Alto, which are of pretty appearance on
account of the contrast of color which the gray or black amor-
phous paste offers to the generally red spherulitic globules. But
the most abundant rhyolites are the petro-siliceous rhyolites of
various shades, red, black, violet, etc., such as those of the
Sierra del Jaral and other points in the vicinity of the regions
of San Luis Potosi, together with those of Guanajuato, Pozos,
Pefioles, etc. Some of the latter frequently are accompanied

A74 OLIVER C. FARRINGTON

by retinites, which may come to predominate, as in the hill
Xicuco between Tula and Mixquiahuala of the state of Hidalgo.
The violet-colored rhyolites that occur in flows in the Tertiary
formations of the Acacico near Yahualica, Jalisco, are notable
for the curious forms (axiolites) which the microfelsitic paste
presents under the microscope; forms very similar to those
which Zirkel describes in a rock from the Black Rock Mount-
ains, Nevada.

In the central part of the country between the parallels 19°
and 21’ N. Lat., a notable eruptive zone exists. In this zone
the appearance of modern eruptives has commenced generally
with the rhyolites, to which have succeeded andesites of a sec-
ond eruption, a lesser number of trachytes and the labradorites
and basalts which form the chief eruptions of the modern vol-
canoes.

The andesites of the second epoch always present characters
by which they can readily be distinguished from those of the
first. The orthorhombic pyroxene, hypersthene occurs fre-
quently among the ferro-magnesian elements of the rocks, now
as a principal and now as an accessory constituent. The micro-
litic feature so marked in the earlier rocks diminishes little by
little and the proportion of the amorphous groundmass, always
devitrified, is increased.

A grouping of the andesites by regions, subdividing them by
varieties of structure or the predominating ferro-megnsian
element, is not practicable on account of the constant change
which occurs in the nature of the component minerals and
degree of crystallization. The hornblende-andesites of a micro-
litic and felsitic magma sometimes containing quartz (dacites)
appear to have been erupted immediately after the rhyolites in
the second andesitic period. The dacites are anterior to the
pyroxene-andesites, likewise of the second epoch, as is shown by
the frequently observed superposition of the latter and by the
thick sedimentary deposits which have covered the dacites.
Alluvium with pebbles of dacite is also found at great depths in
the interior of several of the valleys. The hornblende-andesites

THE ERUPTIVE ROCKS OF MEXICO 475

are distinguished as a general rule from the hornblende-andes-
ites of theformer epoch by the exclusive existence of gray horn-
blende with strong dichroism, altered often in the periphery of the
crystals into ferruginous products. The colors which generally
predominate are grayish-violet and red. The latter color comes
from the alteration of the violet by the decomposition of the
crystals of amphibole into oxides of iron which are disseminated
in the groundmass. The majority are of trachyto-porphyritic
aspect.

Contemporaneous with or perhaps previous to these andes-
ites should be noted the greater part of the hornblendic or
micaceous trachytes whose number is, to be sure, limited, espec-
lally if compared with the number of those which were con-
sidered trachytes before the application of the microscope.
The presence of hypersthene in abundance in andesites marks
the end of the andesitic eruption, since such andesites are seen
alternating with the basalts of modern outflows.

Hornblende-hypersthene-andesites are found in abundance
in many places. Such are localities in the sierra which bounds
the valley of Mexico’on the west, in the valley of Toluca and
in some parts of the Sierra Madre of the state of Chihuahua.
The vitreous types of these rocks and some dacites frequently
occur. These present a vitreous magma having spherulitic and
perlitic structures. Andesitic obsidians with amphibole or mica
are found in dikes as intrusives in the valley of Mexico.

Passing to the andesites made up wholly or chiefly of hyper-
sthene, two varieties may be distinguished: first, those having a
largely microlitic groundmass, and, second, those in which the
amorphous groundmass predominates (andesitic obsidians). In
many localities the two aspects of structure are associated and
the fact that they grade into one another shows that the differ-
ences arise from variations in the conditions at the time of
eruption.

In the andesitic-obsidians the augite appears successively in
the first and second generations and then under a quasi-crystal
Jine form, that is, as a simple devitrification of the amorphous

476 OLIVER C. FARRINGTON

groundmass, or even in very small microlites. The andesitic
eruptions of our volcanoes have produced these vitreous rocks
charged with pyroxene. Such may be seen in the lavas of the
volcano Colima and the early eruptions of Popocatepetl.

While andesites of the vitreous types predominate in the more
recent eruptions, trachytes of the vitreous type alSo Occuia mune
lavas of 1870 thrown from the volcano of Ceboruco furnish us a
good example of this and may be designated as obsidian-like
pyroxene-trachytes. Vitreous trachytes are likewise found in
the volcanoes of Popocatepetl and Colima.

The presence of olivine as an accidental element in these
rocks gives them to the naked eye the appearance of basalts.
With these they have sometimes been confounded owing to the
similarity of color and superficially blistered appearance, com-
mon to the basaltic lavas. There can be no doubt that they
pass from one to another by insensible gradations since the
diminution of oligoclase with the absolute predominance of
labradorite, brings them to basic types represented by labrado-
rites and basalts. Such gradations may be actually observed
in some places in the valley of Mexico.

After the hornblende-andesites, which seem to have suc-
ceeded the rhyolites, the eruptions continued not only by emis-
sion of compact rocks, but also by an enormous quantity of
broken products that were changed to sediments by watery
vapors of the same eruptions and by atmospheric agencies
Thus have originated those thick deposits of andesitic tuffs,
breccias, etc., which are so abundant in different portions of the
great central valleys of the country. The more superficial lay-
ers, having the lightness and fineness of detritus, have indeed
been confounded at times with zolian products.

Lastly may be noted the labradorites, that is, basalts con-
taining no, or only accidental, olivine, and the true basalts which
occur in the volcanic regions or in rare cases rest upon or break
through the Cretaceous limestones.

Labradorites occur in contact with the andesites of the first
epoch and rhyolites, at various points along the eastern slopes of

THE ERUPTIVE ROCKS OF MEXICO 477

the Sierra Madre. Among these points may be mentioned El
Parral, in the state of Chihuahua; E] Nayarit, in the territory of
Tepic; the eastern part of the state of Jalisco; and near the vol-
cano of Jorullo in the state of Michoacan. The early age of
these labradorites is indicated by the fact that olivine is rare
or absent. In the modern labradorites it occurs with more
frequency.

These labradorites frequently exhibit a columnar structure,
the most striking example of which is seen in the famous col-
umns, 130 feet in length, along the Barranca of Regla in the
state of Hidalgo. These stand upon Tertiary tuffs, resting in
their turn upon arenaceous Upper Cretaceous limestones. The
labradorites are compact, of gray color, and contain scattered
grains of olivine. Geodes of zeolites occur in the columns,
chabazite being most common, while thomsonite and arragonite
are also found. The later series of labradorites and basalts con-
tinued up to the latest volcanic eruptions. Examples are found
in the mountains about the valley of Mexico, as in the Pefion de
los Bafios, where pyroxene-labradorites in thin layers exhibit
curious undulations. In some lava flows near the volcano of
Ajusco at the southern part of the valley occur labradorites
formed simply by a marked diminution of the olivine in the
basalts which predominate in the region.

The vitreous hypersthene-andesites which formed the larger
part of the early volcanic outflows were succeeded by basalts
erupted through new volcanic foci. These exhibit an abun-
dance of olivine in a microlitic groundmass of labradorite and
pyroxene. The outflow of basalts in turn ceased, however, and
the field was left anew to the hypersthene rocks which charac-
terize the lavas of the volcanoes now in activity. This alterna-
tion is illustrated by contrasting the olivine-basalts of Jorullo of
the middle of the last century with the present outflows of
Ceboruco and Colima which present good types of trachytes
and pyroxene-andesites with vitreous groundmasses.

In the northern region of the country, over the Mesa Cen-
tral and along various points of the eastern Cordillera Madre,

478 OLIVER C. FARRINGTON

basalts occur cutting their way through Mesozoic sediments and
covering the Tertiary eruptives. In the plain extending to the
south of the Cordillera of Mazapil and in the portion between
the mountains of Grufiidora and Ahorcados, Tertiary basalts
come up through the schistose Cretaceous limestones and along
the upper surface of the latter marked metamorphism has been
produced by the contact.

After the work of eroding waters had filled the valley of
Mexico and made it habitable by man, a mighty cataclysm
devastated the southern part of the valley. A flow of basalt
ten miles in length, accompanied by showers of ashes, came
from the volcano of Xitli and buried much of the inhabited
region. Hence in the layers of pumiceous tuffs upon which
these lavas rest, numerous utensils of primitive industry, human
bones and bones of other modern vertebrates are found. The
volcano of Toluca had ceased activity at this time, but Popocat-
apetl continued to pour forth eruptions of hypersthene-andesites.
The eruptions of the latter volcano ceased at the beginning of
this century, and now only a solfataric activity exists. The
same is true of the Pico de Orizaba.

About the middle of the last century a new volcano appeared
in the Mal Pais in the state of Michoacan. Its products were
black basalts highly charged with olivine. With this last vol-
canic phenomenon was closed the prolonged inundation of
basaltic and andesitic lavas which began to make itself felt at

the end of the Tertiary period.
OLIVER C. FARRINGTON.

LHE -SURALIGRAPHY OF THE: POTOMAC GROUP IN
MARYLAND."

. CONTENTS.

Introduction.

Description of the deposits.

The Patuxent formation.
Name and areal distribution.
Leading features of the deposits.
Characteristic local sections.
Fossils.

The Arundel Formation.
Name and areal distribution.
Leading features of the deposits.
Characteristic local sections.
Fossils.

The Patapsco formation.
Name and areal distribution.
Leading features of the deposits,
Characteristic local sections.
Fossils.

The Raritan formation.
Name and areal distribution.
Leading features of the deposits.
Characteristic local sections.
Fossils.

Interpretation of the deposits.
Sedimentation and structural relations.
Correlation.

The Taxonomic views of other writers.
Comparative Taxonomic table.

INTRODUCTION.

The recent controversy regarding the age of the Potomac
formation, which has been precipitated as the result of the con-
flicting evidence presented by the palaobotanists and the verte-
brate paleontologists, suggests the necessity of determining the

*The investigations have been carried on under the auspices of the Maryland
Geological Survey and the Woman’s College of Baltimore.

479

480 CLARK AND BIBBINS

sequence of the Potomac deposits, together with the horizons
from which the fossils have been derived, if the questions at
issue are to be finally settled. The authors of this paper have
been engaged upon the investigation of these relations during
the past year, and believe that much of the difference of opinion
is due to the lack of knowledge regarding the stratigraphic
position of the beds which have yielded the various plant and
animal remains. They desire at the outset, however, to express
their obligations to their predecessors in the field, without the
results of whose work their own investigations would have been
seriously retarded, if not rendered entirely abortive. The great
volume of data which the paleobotanists have presented to us
during the past few years, and the more meager evidence of the
vertebrate paleontologists, have been of signal service in inter-
preting the stratigraphy of the Potomac formation. It is a
pleasure to witness to the splendid achievements of Professors
Ward, Fontaine, and Newberry, in the study of the fossil floras,
and of Professor Marsh in extricating from poorly fossiliferous
beds the important vertebrate remains which he states he has in
store for us. The junior author of this paper has also made
collections of the flora and fauna which will be discussed by him
in a subsequent contribution.

The conclusions reached by those who have studied these
two classes of organic remains may be briefly stated as follows:
The palzobotanists, largely upon the discovery of dicotyledon-
ous types of plant life, claim the Cretaceous age of the Potomac
group, while Professor Marsh upon the evidence of the verte-
brate remains, particularly of the Dinosauria, is as firmly con-
vinced of the Jurassic age of the deposits.

It seems to the authors that the difficulty lies in the fact that
each side has assumed too largely the unity of the Potomac
group and has not sufficiently regarded the possibility of its rep-
resenting more than a single formation. A marked exception
to this is found in the late work of Professor Ward who has
discovered several distinct stages in the fossil floras—a dis-
crimination which is of much importance in determining the

SiRAITGRAPTY OF THE POTOMAC GROUP 481

stratigraphic relations of the higher portions of the Potomac
deposits.

It is the conclusion of the authors, founded upon a detailed
stratigraphic study of the Potomac group, that all the beds
which have afforded dicotyledonous types of plant life are above
those which have yielded the vertebrate remains, and, more-
over, that a marked unconformity exists between the two
series of deposits. The evidence for this conclusion will be
brought out in the succeeding pages.

DESCRIPTION OF THE DEPOSITS.

The several formations into which the larger unit of the
Potomac group has been divided are as follows:

(Raritan Formation)

Lower Cretaceous - (Patapsco a ) Potomac
Upper Jurassic (?) - ee * Group

THE PATUXENT FORMATION.

Name and areal distribution. —The Patuxent formation
receives its name from the Patuxent River in the basin of which
deposits of this horizon are found typically developed. As the
basal member of the Potomac group the Patuxent formation
occupies a position near the landward margin of the Coastal
Plain, although the higher members of the series frequently
overlap it and are found resting upon the crystalline rocks of the
Piedmont Plateau to the westward. The Patuxent formation has
been traced as a narrow, broken belt from Cecil county across
Harford, Baltimore, Anne Arundel, and Prince George’s counties
to the borders of the District of Columbia.

Leading features of the deposits —The deposits of the Patuxent
formation consist mainly of sand, at times quite pure and gritty,
but generally containing a considerable amount of kaolinized
feldspar, producing a clearly defined arkose. Clay balls are at
times distributed in considerable numbers through the arena-
ceous beds, which in places contain lenses of gravel, sometimes

482 CLARK AND BIBBINS

with cobble stones. Frequently the sands pass over into sandy
clays and these in turn into more highly argillaceous materials
which are commonly of light color, but at times become lead-
colored, brown or red, and not unlike the variegated clays of
the Patapsco formation. Those arenaceous materials which lie
adjacent to ferruginous clays are not infrequently indurated by
hydrous oxides of iron, forming ferruginous sandstone. The
more arenaceous deposits are commonly cross-bedded, and the
whole formation gives evidence of rapid deposition.

The strike of the beds is in a general north-northeast south-
southwest direction, corresponding to the eastern border of. the
Piedmont Plateau. The dip of the strata, so faras can be deter-
mined from the narrow exposures which have been obtained,
is probably between thirty and forty feet to the mile. The
irregular character of the sedimentation, together with the small
areal extent of the deposits, renders it very difficult to make any
satisfactory measurement.

The thickness of the Patuxent formation is rather variable,
but, so far as has been determined, has not been found to exceed
150 feet, although it may be considerably thicker at some points.

Characteristic local sections-—The deposits of the Patuxent
formation outcrop, among other places, in the valley of the Little
and Big Patuxent rivers, having been reached in the iron-ore
openings which have been made at many points in the overlying
Arundel formation. An excellent section is found in a cutting
on the Baltimore and Ohio Railroad a short distance to the
south of Contee. At the latter locality the coarse gravelly
phase of the formation is well developed, and is unconformably
overlain by the iron-ore clays of the Arundel formation. At the
southern end of the cut the gravels have become cemented near
the contact with the Arundel into a considerable ledge of con-
_glomerate, by the leaching into them of the hydrous oxide of
iron from the overlying deposits.

One of the most comprehensive sections of the Patuxent
formation is at School House Hill, Baltimore county, about three-
quarters of a mile northwest of Lansdowne on the Baltimore and

STRATIGRAPHY OF THE POTOMAC GKOUP 483

Ohio Railroad, where a gulch, known as ‘Deep Ditch,” on the
southern side of the hill, has opened up one of the finest sections
of the Potomac group. The Patuxent, Arundel, and Patapsco

Fic. 1. View at School House Hill, Baltimore County, showing Patuxent sands
overlain by Arundel clays.

formations are all exposed at this locality. The section is as
follows:

SECTION AT SCHOOL HOUSE HILL, BALTIMORE COUNTY.

Patapsco. Argillaceous sands more or less iron-stained, with varie-

gated clays, and with ferruginous crusts ; ash-colored, lig-

nitic and somewhat indurated toward the base; silicified
coniferous and cycacean trunks. . . - - Eon ite

Arundel. Slightly indurated, ferruginous ledge containing abundant
impressions of monocotyledonous plants. - - aE it,

Drab-colored clays, with beds of lignite, containing

“brown”’ and ‘white ore,’”’ exhibiting impressions of ferns;
dinosaurian teeth; ferruginous ledge at base. - - - 50 ft.

484 CLARK AND BIBBINS

Patuxent. Compact, yellowish, reddish, and variegated sands, locally
carbonaceous; brown clays containing flakes of iron ore
(hydrous oxide); lead-colored clays with fragmentary plant
remains; ferruginous ledge containing pipe ore. - - 30 ft
Compact jointed clays of great variety of color, red,
lilac, and white predominating; ‘‘ paint rock” and lenses of
coarse gravel containing balls of clay and silicified conifer-

ous wood, passing into - - = - - - - 20 ft
Cross-bedded sand, slightly carbonaceous - - - 10 ft
Total thickness, - - - - - 121 ft

The slope of the hill is thickly covered with a wash com-
posed of highly ferruginous sand charged with broken crusts of
ironstone,

Another section of much interest is found near Federal Hill
Baltimore city, where the Patuxent sands are apparently directly
overlain by the Patapsco formation, lenses of the Arundel for-
mation having been observed occurring in their proper strati-
graphic position in the immediate vicinity. The section at
Federal Hill, somewhat generalized, is as follows:

SECTION NEAR FEDERAL HILL, BALTIMORE CITY.

Raritan. Sand and ferruginous sandstone containing silicified
coniferous wood - - - - - =) 5 ftaomm'
Carbonaceous clays containing flakes of “white ore” 1 ft. 4 in
Patapsco. Variegated clays with ironstone crusts - - = By ite, © iim
“Short” blue slickensides clay with logs of lignite
and occasional fern impressions - - > 7p ittks © Was
Fossiliferous “slaty clay,’’ with ferns, cycads, coni-
fers, monocotyledons and dicotyledons - - - 7 ft. Io in.
Indurated ferruginous layer containing “paint rock’’ _o ft. 6 in.

Arundel. Represented in immediate vicinity by lenses of lig-
nitic clay with nodules of “white ore” and its

derivatives - - - - - - =) (outt) opm

Patuxent. White sand - - - - - - - 7, eons
Coarse sand with clay-balls — - - - - = AG te onins

White clay - - - - - - - i sales () THN,

Indurated gravel - - : - - - =) 9) ASE opine

Total thickness - - - - - 76 ft. 8 in.

SURATIGRAPHY (OF THE POTOMAC GROUP 485

Many other occurrences of the Patuxent formation might be
cited both to the north and south of Baltimore, but enough
have already been given to show its character and relations.

Fossils—Very few traces of organic remains have as yet
been found in the Patuxent formation. Those which have been
obtained consist of lignetized coniferous wood, and various
indeterminable vegetable fragments, among which no traces
of dicotyledonous forms have been observed. A silicified
coniferous trunk has been found zm s¢tu at School House Hill.
One cycad trunk is also reported to have been seen in place in
these beds. No animal remains have yet been with certainty
detected.

THE ARUNDEL FORMATION.

Name and areal distribution — The Arundel formation receives
its name from Anne Arundel county where the deposits of this
horizon are well developed. It has been traced as a broken
belt all the way from Cecil county to the borders of the District
of Columbia, and occurs as long narrow belts that extend ina
general northwest-southeast direction forming a low angle with
the border of the Piedmont Plateau.

Leading features of the deposits—The deposits consist of a
series of large and small lenses of iron ore-bearing clays which
occupy ancient depressions in the surface of the Patuxent forma-
tion. These clays as most typically developed (‘blue charcoal
clays’’ of the miners) are drab colored, tough, and frequently highly
carbonaceous, lignitized trunks of trees and limbs lying horizon-
tally strongly compressed and frequently charged with or
enclosed by carbonate and sulphide of iron. Sometimes these
trunks are encountered in an upright position, with their larger
roots still intact. Scattered through the dark clays are vast
quantities of nodules of iron carbonate, at times reaching
many tons in weight, and known to the miners as ‘white ore,”
‘hone ore”’ or ‘‘steel ore.’’ Inthe upper portions of the for-
mation which have been exposed to atmospheric influences the
carbonate ores have sometimes to considerable depth changed

486 CLARK AND BIBBINS

to hydrous oxides of iron, which the miners recognize under
or ‘‘red”’ ore. Under these conditions

d

the name of ‘‘brown’
also the originally drab-colored clays containing the carbonate

Fic. 2. Section at Reynold’s Mine, Anne Arundel County, showing Arundel
clays overlain by Patapsco formation.

ores have suffered a like chemical change, resulting in red or
variegated clays. Where these clays chance to contain but
little lignite the iron ore may consist almost entirely of these
oxides.

The peculiar relations which the Arundel formation presents
to the other members of the Potomac group render it difficult to
say much regarding the strike and dip of the deposits, although
the fact that they lie exposed in depressions upon the surface of
the Patuxent formation renders it probable that these’ features do
not differ materially from that observed in the other formations.

The lenses vary greatly in thickness, and from their charac-
ter are at times lacking in portions of the country. The esti-

STRATIGRAPHY OF THE POTOMAC GROUP 487

mates which were made of the thickness of the largest lenses
observed render it probable that they attain at least 125 feet.

‘Characteristic local sections—QOne of the best sections is
found at Reynold’s Mine on Piney Run, Anne Arundel county,
one mile south of Hanover. It occurs on the western flank of
the so-called “Elk Ridge” in a heavy lense constituting its
axis and largely conditioning its existence. The section at
‘Reynold’s Mine is as follows:

SECTION AT REYNOLD’S MINE, ANNE ARUNDEL COUNTY.

Raritan. White and light brown sand and gravel containing
crusts of iron-stone - - - - - =" Rov Oram,
Patapsco. White, varigated argillaceous sands, “fuller’s earth,”
clay and paint clay, with paint rock at the base;
silicified coniferous and cycadean trunks. = PDOukt..OF1n-
Ferruginous ledge, more or less conglomeritic —- o ft. 3 in.
Arundel. Drab colored compact laminated clays containing
beds of lignite and bearing fern impressions ;
nodules, flakes and ledges of ‘ white ore,” slightly
plant bearing - = - - - - - 70+ ft.

Total thickness” - - - - - go ft. 3 in.

Another important section is found at Muirkirk, Prince
George’s county, where also the iron ore clays have been
extensively worked for many years. The Muirkirk section
exposed at the “‘Old Blue Bank” on the Tyson estate is as

follows:

SECTION OF ‘‘OLD BLUE BANK’ MUIRKIRK, PRINCE GEORGE'S

COUNTY.

Raritan. Sandy gravel’ - - - - - - - Bieceatdae, ober

Patapsco. Mottled gravelly loam; silicified coniferous and cyca-
dean trunks” - - - - - - - P22 afte

Arundel. Massive blue clay containing ‘white ore;” bones of
Dinusauria at base - - - - - = 4 QOVa TEE
Highly lignitic lens with “charcoal ore”’ . - 20 2 Ett
Tough, “dry,” blue clay with ‘“‘white ore” - - <a) Ge Pett
Patuxent. White sand~ - - - - - - - - 1o-+ ft.

Total thickness” - - . - - = OS tamte

CLARK AND BIBBINS

488

ine,

Arundel formation showing nodules of “white ore” at Reynold’s M

Anne Arundel County.

FIG. 3.

STRATIGRAPHY OF THE POTOMAC GROUP 489

Many other characteristic local sections might be given,

since the Arundel formation has been opened at numerous
points for iron ore. Lenses have been observed among other
places at the head of Elk River neck in Cecil county, in
the vicinity of Joppa, Harford county, on Stemmers Run,
Baltimore county, at Locust Point, Baltimore city, and at
numerous localities in Anne Arundel and Prince George’s
counties.
« Fossils —Animal and plant remains have been observed at
several localities in the Arundel formation. The Muirkirk area
has afforded much the largest number. It was in this section
that the vertebrate and cycadean remains of the Potomac group
were first discovered by Mr. Philip T. Tyson. Later Professor
O. C. Marsh of New Haven made extensive collections at this
locality and upon this material based his conclusions regarding
the age of the Potomac group. The vertebrate fossils consist
largely of Dinosauria.

The plant fossils consist of ferns, conifers and mono-

cotyledons. No dicotyledonous forms have yet been recog-
nized.

THE PATAPSCO FORMATION.

Name and areal distribution. — The Patapsco formation is

so called from its typical occurrence in the valley of the
Patapsco River. It extends entirely across the state from the
Delaware border to the Potomac River, and throughout this
distance is one of the most important members of the Potomac
group. It has a much larger areal extent than either of the
two formations before described, and in places overlaps them,
resting directly upon the crystalline rocks of the Piedmont
Plateau.

Leading features of the deposits—The deposits of the Patapsco
formation consist chiefly of highly colored and variegated
clays which grade over into lighter colored sands and clays,
while sandy lenses of coarser materials are sometimes interstrati-
fied, which are occasionally indurated and at times form “pipe

490 CLARK AND BIBBINS

ore.” The clays are in places dark colored, massive and
more or less lignitic. At times they are laminated (‘slaty’’)
and bear large numbers of leaf impressions. Fossiliferous

’

flakes and nodules of ‘‘white” and ‘‘red ore” also occasionally
occur. The sands sometimes contain much decomposed feld-
spar, and rounded lumps of clay are also found. The sands are
frequently cross-bedded and give evidence of rapid deposition.
Workable beds of ‘paint rock,” as the highly ferruginous clays
are termed, are found at many points, usually near the base of.
the formation.

The strike of the formation has a general north-northeast
south-southwest direction, following the eastern margin of the
Piedmont Plateau. The dip of the beds is somewhat less than
that of the underlying formations, the deposits of the Patapsco
formation transgressing the older strata, and as a result often
come to lie directly upon the crystalline rocks to the west-
ward.

A very marked unconformity is found between the deposits
of the Patapsco and underlying formations. The thickness of
the formation is estimated to reach fully 200 feet.

Characteristic local sections —In addition to the several char-
acteristic sections which have been already given, in which
deposits of the Patapsco formation are found represented, the
highly important locality of Cedar Hill in the area of Timber
Neck in Anne Arundel county is also described. The section
is on Licking Run one mile southwest of Hanover and is as
follows:

SECTION AT CEDAR HILL, ANNE ARUNDEL COUNTY.

Raritan. Reddish sands, somewhat gravelly, containing “pipe ore” 12 ft.
Patapsco. White, red and brown sands, more or less argillaceous,
containing clay pellets” - - - - - =eeZOnLte
Arundel. Drab colored pyritous clays with beds of lignite; pellets,
nodules and flakes of carbonate of iron (“white ore”) Ioo ft.
White clay (in bed of Licking Run) - - - SG lit

Total thickness - - - - - - WOT silt

STRATIGRAPHY OF THE POTOMAC GROUP 491

Another interesting section is found on the opposite side of
Licking Run in Reynold’s ‘‘Spring Drain’? mine, where the
basal member of the Patapsco formation consists of a ledge of

Fic. 4. View of Timber Neck, Anne Arundel County, showing Arundel, Pata-

psco, and Raritan formations.

ferruginous conglomerate and is found lying unconformably
upon the Arundel iron ore clays below. Innumerable sections
of the Patapsco deposits are found in other mines and along
the streams, railroads, and highways which cross this region.

Fosstls.—The fossils which have been found in the Patapsco
formation consist chiefly of plant remains. A few poorly pre-
served molluscan shells have been observed but no study has
yet been given to them. No dinosaurian remains have yet been
with certainty detected.

The plant remains consist mainly of ferns, cycads, conifers,
monocotyledons and dicotyledons. The dicotyledonous forms
are not uncommon and according to Professor Lester F. Ward

492 CLARK AND BIBBINS

who has made a very exhaustive study of the flora from this
horizon, represent among their number a few archaic types,
while others approach quite closely to modern types of vege-
tation.

THE RARITAN FORMATION.

Name and areal distribution—The Raritan formation receives
its name from the Raritan Bay, New Jersey, where the deposits
of this formation are typically developed. The name was given
by the senior author of this paper in the annual report of the
state geologist of New Jersey for 1892 although the term Raritan
clays had been somewhat loosely used for deposits of this age
by earlier writers.

The Raritan formation extends as a constantly narrowing
belt from northern New Jersey into Maryland and disappears by
the transgression of the upper Creteaceous formations near the
borders of the District of Columbia.

Leading featurcs of the deposits —TVhe deposits of the Raritan
formation consist of sands and clays, the former largely pre-
dominating in the upper portion of the formation. The sands
are frequently very pure and white but at times, especially in
the lower portion of the formation are more or less colored and
indurated by hydrous oxide of iron which produces the char-
acteristic tube-like structure which is known as ‘pipe ore.’
The indurated beds are well exhibited at Rocky and Stony
creeks on the south side of the Patapsco River, and at White
Rocks in the immediate vicinity. The latter locality afforded the
name of ‘‘ Albirupean”’ which was applied by Professor Uhler to
the upper portions of the Potomac group.

The clays are generally of very light color but at times
become dark colored in the leaf-bearing zones. Beds of brown,
black or earthy lignite, containing much pyrites, and occasion-
ally amber (Cape Sable, Magothy River), have been observed at
a few points. The clays are generally more or less arenaceous
and grade over into the sandy deposits which largely character-
ize this formation.

SLIRATIGRAPHY OF THE POTOMAC GROUP 493

The strike of the beds is ina generally north-northeast to
south-southwest direction, corresponding to the Patapsco for-
mation already described. The dip of the strata is probably

Fic. 5. Section of Raritan formation near Rocky Point above Round Bay,

Severn River, Anne Arundel County, showing hard sandstone ledges at the right and
white cross-bedded sands in the center.

slightly less than that of the underlying formation, and a slight
transgression is noticeable to the northward.

The thickness of the Raritan formation in central Maryland
is probably not far from 500 feet. It declines in thickness
gradually to the southward where it finally disappears near the
limits of the District of Columbia.

Characteristic local sections —Very characteristic sections of
the Raritan formation are shown in the bluffs of the Severn
River in the vicinity and about Round Bay. On Rocky Point
just above Round Bay an excellent exposure of the Faritan
sands with the interbedded clays is exhibited, with a capping

494 CLARK AND BIBBINS

of marine Cretaceous. The section at this point is as fol-

lows:
ROCKY POINT, ROUND BAY, SEVERN RIVER.
Matawan. Black laminated sands highly weathered, producing
a reddish and grayish motted appearance to ft.
Raritan. Coarse, gritty sands with lenses of clay; the sand
cross-bedded and often indurated, forming heavy -
ledges of ironstone 30 ft.
Total thickness Ao ft.

Other excellent sections are seen on the Magothy River, on
the Lower Patapsco and its tributaries, on Elk Neck, and near
the mouth of the Sassafras River, in which very much the same
characters are exhibited. The light colored sands are espe-
cially well developed on Elk Neck where they attain a very
great thickness.

Fossils —The fossils of the Raritan formation consist mainly
of plant remains. Several brackish water molluscan shells have
been obtained from the Raritan formation, farther to the north
in New Jersey and it is not improbable that the same may be
observed in Maryland when the deposits have been further
studied. The fossil plants include dicotyledons of much more
recent affinities than those of the Patapsco formation, the break
between the two floras being very marked.

INTERPRETATION OF THE DEPOSITS.

The interpretation of the Potomac group involves the con-
sideration of the sedimentation and structural relations of the
deposits as well as of the entombed fossils, and each has an
important bearing in the elucidation of the other. The con-
ditions of sedimentation explain in no small degree the char-
acter of the fauna and flora while their features likewise throw
light upon the physical conditions which existed during Potomac
time.

Sedimentation and structural relations —The sedimentation of
this period can best be understood after an examination of

STRADIGRAPAVOOR THE POLOMAC GROUP 495

the physical conditions which prevailed during the time immedi-
ately preceding the opening of Potomac deposition. The results

of recent work in the study of the physiography of the North

Fic. 6. Section below Round Bay, Anne Arundel County, showing Raritan
formation overlain by Matawan formation.

American continent during the Mesozoic show that the eastern
side of the country had been largely base-leveled, so that a long
period of rock disintegration preceded the Potomac. With the
advent of this period the land was tilted southeastward, and the
increasing erosion brought about by this movement afforded
the deposits of the Potomac group. That this movement was
not continuous or persistent in the same direction is evidenced
by the varying character of the deposits which have been already
described. With the close of Potomac sedimentation a gradual
transgression of the later marine formations across the margin

496 CLARK AND BIBBINS

of the Potomac group took place, by means of which the higher
strata were gradually cut off to the southward. The details
of this transgression will be further explained in the subsequent
pages.

The basal deposits of the Potomac group, which have been

described under the name of the Patuxent formation, indicate
in their arkosic character, their proximity to the ancient con-
tinent, the rocks of which had suffered extensive disintegration.
These features so pronounced where the deposits he adjoining
geneissic or granitic rocks largely disappear where these rocks
are poorly developed and where the deposits themselves were
evidently laid down at some distance from the old shore line.
Rapid deposition in shallow waters is seen in the cross-bedded
character of the strata and their rapid change in character
The appearance of clay balls, so widely disseminated at certain
points, as above described, indicates the shallowing of the seas
and the breaking down of pre-existing clay beds by wave action
and the incorporation of the rolled materials by the later
deposits.
_ The close of the Patuxent epoch was evidently marked by a
gradual elevation of the deposits and the trenching of the surface
by streams, so that a series of broad, shallow valleys was formed
While this was going forward, a landward depression of the con-
tinent border evidently took place, producing series of long
marshes in the ancient valleys, in which sedimentation was slow
and in which swamp vegetation flourished. The tough clays,
filled with lignitic accumulation, in which the tree trunks are
sometimes found erect, with their roots still intact, can hardly
find a satisfactory explanation upon any other basis. It was in
these ancient marshes that the iron was deposited. It is also
probable that some connection existed between these marshes
and the area of basic eruptive rocks of central and northern
Maryland. It was in these marshes that the bones of Dinosauria
became entombed which, with the evidences of dense vegeta-
tion, suggests a sub-tropical climate.

The marked line of unconformity separating the Patapsco

STRATIGRAPHY OF THE POTOMAC GROUP 497

formation from the two basal members of the Potomac group
points to elevation after the close of the Arundel epoch and toa
prolonged period of denudation. A striking feature of this
erosion is the greater resistance which the Arundel clays pre-
sented when compared with the deposits of the Patuxent forma-
tion. The partially eroded clay lenses which project above the
com.non line of contact can readily be explained upon these
grounds. It was over this uneven surface that the deposits of
the Patapsco formation were spread, reaching far beyond their
western limits until they rested directly upon the crystalline rocks
of the Piedmont Plateau. Their materials, so largely arkosic in
the vicinity of the feldspathic rocks (gneiss and granite), point
to the rapid stripping off of the disintegrated surface materials,
and their deposition along the continent border. To how large
an extent subsequent disintegration has kaolinized these mate-
rials it is difficult to determine, but that they had been exten-
sively weathered prior to their removal seems justified. The
highly colored and variegated clays which were evidently formed
in the quieter and deeper waters of the Patapsco epoch bear
some relation to the great belts of basic eruptive rocks which lie
to the west and north of them. This phase of sedimentation is
much more marked in central Maryland where the rocks of this
character are most highly developed and where the proximity to
the eastern margin of the Piedmont belt is most apparent. It is
also probable that these highly colored clays were in part
derived from the weathered surface of the Arundel iron-ore
beds.

The unconformity separating the Raritan from the under-
lying deposits is less prominent than that which has been above
described at the base of the Patapsco formation, although the
gradual thinning of the Patapsco along its western margin and
the overlapping of the Raritan points strongly toward a struc-
tural break. The Raritan deposits also obliquely transgress the
other materials of the Potomac group northward until in the
Delaware valley they come to rest directly upon the crystalline
rocks of the Piedmont belt. The thick deposits of sand and

498 CLARK AND BIBBINS

clay indicate rapid deposition in shallow waters and the general
continuity of the beds points to wider and deeper water areas.
The close of Raritan sedimentation by the depression of the
continent border and the gradual transgression of the deposits
of the marine Cretaceous southward is a phenomenon of unusual
interest.

The line of unconformity which separates the Potomac group
from the later Cretaceous formations is so poorly defined in
local sections that absolute unconformity could hardly be proved
except by the evidence of this gradual southward transgression
which finally cuts off the entire Raritan formation on the banks
of the Potomac River.

This review of the conditions of sedimentation during the
Potomac period and of the relations which the individual for-
mations hold to one another and to the rocks above and below
them points to the probability of the existence of extended areas
of fresh and brackish waters along the eastern border of the
North American continent during Potomac time. Just how these
conditions could have been produced in all instances is not clear
and speculation regarding them seems hardly warranted by the
facts which are at present before us.

Correlation.— The correlation of the formations composing
the Potomac group must rest largely upon the fossils which
have been derived from them, although the physical history
of the continent renders it possible to establish certain broad
comparisons along the Atlantic and Gulf borders that are not
without their value. The similarity of conditions during the
deposition of the Tuscaloosa beds in the south is clearly indi-
cated, and the corroborative evidence which paleontology
affords in this connection will be presently mentioned.

As was stated in the introduction to this article the tendency
of most authors hitherto has been to regard the Potomac group
as a single stratigraphic unit and the discovery of fossils of
known affinities within its beds to be conclusive evidence of the
age of the entire series of strata. FYrom what has been said in the
preceding chapters it is evident that the Potomac group is made

SIRATIGRAPHY OF THE POTOMAC GROUP 499

up of a series of formations, containing clearly defined faunas
and floras, and separated by marked structural breaks at various
points. It is necessary, therefore, to correlate each division of
the group upon its own merits, and not upon the floral or faunal
relations of the underlying and overlying formations.

The absence of knowledge regarding the character of the
organic remains entombed in the Patuxent formation renders it
impossible to speak with definiteness regarding the age of this
division. Its position beneath the Arundel beds and the physi
cal relations which it holds to this formation render it probable
that they must both be assigned to approximately the same
position in the geological time scale. The Arundel formation
has afforded a number of vertebrate forms, largely Dinosauria,
which Professor Marsh regards as indisputable proof of the
Jurassic age of the deposits. The fossil plants which have been
hitherto found in this formation are altogether in harmony with
this view. No dicotyledonous types have been observed, while
the ferns, conifers and monocotyledons could, so far as at present
known, be as well referred to the Jurassic as to a later horizon.
The evidence afforded by the vertebrate fossils is unfortunately
incomplete as but few forms have as yet been figured and des-
cribed, although Professor Marsh states that he possesses a large
amount of unpublished material which fully corroborates the views
which he has promulgated regarding the age of these beds. Pro-
fessor Marsh admits the equivalence of these beds with portions
at least of the Wealden formation of Europe which most authorities
refer to the Cretaceous. The final interpretation of the verte-
brate fauna evidently involves, therefore, the determination of
the upper limits of the Jurassic itself rather than the correlation
of the Potomac group simply, and this article is hardly the place
to discuss the merits of so broad a question. It is not impossible,
however, that portions of the Potomac as well as the Wealden
may antedate the oldest known marine Cretaceous, and for that
reason as well as on account of the distinguished authority of
Professor Marsh the Patuxent and Arundel formations are pro-
visionally referred by the authors to the Jurassic. The discov-

500 CLARK AND BIBBINS

ery of vertebrate remains of Jurassic affinities in these forma-
tions is not, however, sufficient grounds for the reference of the
entire Potomac group to the Jurassic period.

The Patapsco formation has afforded a rich flora in which
dicotyledonous types are not uncommon. The fact that dicoty-
ledonous forms have never been found elsewhere in rocks earlier
than the Cretaceous is strong presumptive evidence of the
Cretaceous age of these deposits; at the same time the fact that
many other forms are identical or closely related to those of
European horizons, generally referred to the Cretaceous, further
substantiates this view. It is the opinion of Professor Ward,
who has exhaustively studied the flora of this formation, that it
is equivalent to the lower divisions of the Lower Cretaceous of
Europe. Professor Ward has divided what the authors here
recognize as a single stratigraphic unit into several zones, each
with its characteristic plant forms, which, he states, give evi-
dence of constantly progressive types in passing from the lowest
to the highest members of the series. Whether these different
zones represent a sequence of floras, or to a considerable extent
local aggregations of forms under different physical conditions
but of equivalent age, the authors are unable to determine,
although they strongly incline to the latter view. The abun-
dance of vegetation having a prominent cycadean element sug-
gests a repetition of the mild climatic conditions which prevailed
during the Arundel deposition.

The fossils of the Raritan formation are in the main distinct
from those of the Patapsco and include a large assemblage of
dicotyledonous types with much more modern affinities. Simi-
lar forms are found in the Tuscaloosa beds of the south, and
it is the belief of Professor Ward that these deposits repre-
sent the Raritan formation in the north. The Raritan beds
show strong floral affinities with the upper portions of the lower
Cretaceous of Europe (Albian), and, according to Professor
Ward, it is not impossible that the higher members of this for-
mation to the north of New Jersey may even represent the basal
portions of the upper Cretaceous as well (Cenomanian).

SPRATIGRAPAY OF THE. POTOMAC GROUP 501

The Patapsco and Raritan formations have afforded no
animal remains which are of determinative value; the fossil
plants all point strongly to the lower Cretaceous age of the
beds. So large an amount of evidence has been brought for-
ward in support of this view by Professors Ward, Fontaine and
Newberry, that the authors have no hesitancy in accepting their
_conclusions, and these two formations are therefore placed in the
Cretaceous.

THE TAXONOMIC VIEWS OF OTHER WRITERS.

The earlier writers did not differentiate the Mesozoic deposits
of the middle Atlantic slope into independent formations. For
many years the basal clays and sands, which border the crystal-
line rocks of the Piedmont Plateau on the east, were considered
the eastern equivalent of the red sandstones and shales with
their enclosed coals farther west.

Professor W. B. Rogers, state geologist of Virginia, first
sharply differentiated the eastern deposits from the western, and
described the former under the name of the ‘‘Upper Second-
any. in his state report. In later articles Professor Rogers
refers these deposits ‘‘at least in part to the horizon of the
Upper Jurassic. Possibly we may find here a passage group
analogous to the Wealden of British Geology.”* On his geo-
logical map of the Virginias, and in his more recent publications,
the deposits of the Potomac group are referred to as the
‘‘Jurasso-Cretaceous.”’

In the reports of Professor J. T. Ducatel, who was state
geologist of Maryland between the years 1834 and 1841, com-
paratively little attention was given to the clays and sands at
the base of the Coastal Plain series, and neither their strati-
graphic nor taxonomic position was clearly defined. The
reéstablishment of official geological work in Maryland by
Philip T. Tyson,3 who, as state agricultural chemist, published

*Geology of the Virginias. Report of 1840, p. 438.

? Geology of the Virginias, p. 712.

3First Rept. State. Agri. Chem., 1860, pp. 41-43.

502 CLARK AND BIBBINS

his first report in 1860, led to a much fuller description of the
Potomac deposits. He recognized two divisions in these basal
strata, although his descriptions do not make it altogether clear
that he understood their stratigraphic relations. He, however,
differentiated the ‘‘Iron-ore Clays” which he described and
mapped as distinct from another member composed of variegated
materials (‘‘a thick group of sands and clays of various colors’’).
He stated that this latter member in places abounded in lignite
derived from coniferous plants, and in places contained beds of
ferruginous sandstone. These deposits were referred with the
sandy clays and greensand above them to the Cretaceous or
Upper Secondary. In his second report, published in 1862, he
referred the ‘“‘Iron-ore Clays,’ on the supposed occurrence of
fossil cycads in the beds, to the ‘‘ Oolitic period.”

In the “Memoir of the Geological Survey of Delaware,’’*
published by Professor J. C. Booth, the state geologist of Dela-
ware, in 1841, the deposits which we are now considering were
denominated the ‘Red Clay formation,’ and together with the
‘Greensand formation”’ above them classed as ‘‘ Upper Second-
ary Deposits.”

Professor H. D. Rogers, who published reports upon the
geology of New Jersey in 1836 and 1840, described the deposits
of that region as ‘‘Clays and Sands” without clearly defin-
ing their stratigraphic relations. Upon the organization of
the second Geological Survey of New Jersey in 1854 under the
direction of Wm. Kitchell, Professor George H. Cook began his
extended investigations of the Coastal Plain series of that state.
At a later period, as state geologist, he elaborated and classi-
fied these deposits in a manner that for many years met with
wide acceptance. This classification is given in much detail in
the Geology of New Jersey published in 1868.2 The lowest of
these formations is described by Professor Cook under the name
of ‘Plastic Clays” and referred by him to the Cretaceous.

Little further attempt was made at the investigation of the

*Mem. Geol. Surv. Del., pp. 38-43.
* Geology of New Jersey 1868, pp. 249-257.

STRATIGRAPHY OF THE POTOMAC GROUP 503

Potomac deposits until almost within the last decade. In 1885
Professor R. P. Whitfield, as the result of several years’ study,
published an important monograph upon ‘‘The Brachiopoda and
Lamellibranchiata of the Raritan Clays and Greensand Marls of

’

New Jersey,” in which several Lamellibranchs from the ‘Plastic
Clays” of Professor Cook are described. While the investiga-
tions leading up to Professor Whitfield’s report were in progress
Professor William M. Fontaine, of the University of Virginia,
began his elaborate study of the Mesozoic flora of Virginia.
The published account of this work, however, did not appear
until after the important stratigraphic study of Professor W J
McGee, of the United States Geological Survey, which began a
few years subsequently.

The investigations of Professor McGee upon the Potomac
deposits were seriously commenced in the summer of 1885, and
were participated in by Professor L. F. Ward, of the United
States Geological Survey, and these gentlemen also codperated
soon after with Professor Fontaine. Some preliminary work
had already been done by Professor McGee’ in the previous
year and the name ‘“‘Potomac formation”’ proposed. Professor
McGee continued his investigations of the Potomac formation
during several years, and published a number of important
papers regarding its stratigraphic features, the most compre-
hensive of these being entitled ‘‘Three Formations of the Middle
Atlantic Slope.”’?

During this same period Professor P. R. Uhler,3 of Baltimore,
investigated the relations of the Potomac deposits in the
Patapsco basin of central Maryland and proposed the division of
these basal deposits into a lower member which he called the

”)

‘‘Baltimorean,” and an upper member which was designated the
“Albirupean.” In later publications+ the term Potomac was
accepted as the equivalent of the Baltimorean, and the ‘“‘Alter-

*Rept. Health Officer, Dist. Columbia 1884-5 (1886), p. 20.

? Amer. Jour. Sci., 3d ser. Vol. XXXV, 1888, pp. 120-143.

3Proc. Amer. Phil. Soc., Vol. XXV, 1888, pp. 42-53.

4Md. Acad. Sci., Vol. I, 1892, pp. 185-202.

504 CLARK AND BIBBINS

nate Clay Sands” placed at the top of the group as part of the
Albirupean.

The senior author of this paper, in a study of the Coastal
Plain formations of New Jersey, proposed in 1892 the name
“Raritan formation’’* for the ‘Plastic Clays” of Professor
Cook, the term Raritan having been somewhat loosely used by
several authors in earlier years in speaking of the clay deposits
of this formation.

Mr. N. H. Darton,? of the United States Geological Survey,
as a result of his study of the Coastal Plain in southern Mary-
land, differentiated a part of the sands at the top of the Potomac
group as the ‘“‘Magothy formation,” which he considered might
be equivalent to Professor Uhler’s ‘Alternate Clay Sands.”

The elaborate investigations of Professor Ward, which began
as already described in 1885, have been continued to the present
day. His exhaustive researches upon the fossil plants in the
Potomac group have added largely to our knowledge of that
formation. His most important publication? appeared in 1895,
in which the Potomac formation is subdivided into a number of

series, ViZ.:—
Albirupean Series, Newer Potomac.
Iron Ore aS
Aquia Creek ‘“
Mt. Vernon ‘“ Older Potomac.

Rappahannock Series,
James River is

__~,-_

The interest aroused in the age of the Potomac formation
led tothe collection by Mr. J. B. Hatcher under the direction of
Professor O. C. Marsh‘ of the United States Geological Survey
of vertebrate remains from the iron ore beds in the vicinity of
Muirkirk, Prince George’s county, Maryland. Upon the basis
of these remains Professor Marsh has unequivocally referred
the Potomac group of Maryland to the Jurassic. He has sub-

t Ann. Rept. State Geol., N. J., 1892 (1893), pp. 181-186.

2 Amer. Jour. Sci., 3d ser., Vol. XLV, 1893, pp. 407-419.

315th Ann. Rept. Dir. U.S. Geol. Survey 1893-4 (1895), pp. 307-397.

4 Amer. Jour. Sci., 3d ser., Vol. XX XI, 1888, pp. 89-97.

505

STRATIGRAPHY OF THE POTOMAC GROUP

COMPARATIVE TAONGMIC TABLE.

CRETACEOUS

JURASSIC ?

———

(

4

Rogers’ tenn | eG, Pan eCiee | Repeee | ay, Sen Way ale WANE | ER Nee ED a aOUC i008
(state (aren), Booth Tyson Cook | Whitfield |Newberry] McGee | Fontaine | Uhler Darton Marsh Ward
report)
? ? ? Alter-
Raritan nate ee Albirupean
E ] agot i
Plastic | Raritan | Amboy : oy ae Zl ckee
sands
clays clays clays
? ?
Albiru- Potomac] Iron ore seri
Upper | Jurasso-|Red clay} Varie- Potomac|Potomac] pean (gman. aN on Gee
Patapsco| Secon- | Creta- | Forma- | gated or sic) dais
dary ceous tion clays Younger Mite AVesaeGr
(upper | and Meso- eee
| secon- | sands zoic |Potomac}/Potomac R |
dary) - appahannock
Arundel Baltimo ScHesy
nee James River
series
2
Patuxent
Tron ore
clays
? ?

506 CLARK AND BIBBINS

sequently placed all of the Coastal Plain deposits beneath the
marine Cretaceous in the same geologic division.* Professor
Marsh claims the more recent discovery of a large amount of
vertebrate material which throws much light upon the age of
the Potomac formation and which he proposes shortly to describe.
The last contribution of Professor Marsh brought about an
extended discussion regarding the age of the Potomac group
which was participated in by Messrs. Gilbert,? Marcou,3 Hollick,
Hill,4 and Ward.5

The important postumous work of Professor J. S. Newberry
entitled “The Flora of the Amboy Clays’’® is a valuable con-
tribution to the geology of the New Jersey portion of the Raritan
formation. This work, which was edited by Arthur Hollick,
represents the results of many years of investigation on the part
of the late Professor Newberry.

The conclusions of the authors of this paper, as set forth in
the preceding pages, are formed upon an extensive study of
the Potomac group both in Maryland and New Jersey, and are
seen to be quite different from those advanced by their predeces-
sors. The comparative table on page 505 exhibits in a graphic
manner the taxonomy of the several writers referred to, as inter-

preted by the authors of this paper.
Wm. BULLOCK CLarRK,

GEOLOGICAL LABORATORY, ARTHUR BIBBINS.
JoHNs HOPKINS UNIVERSITY,

July 1897.

tJurassic Formation of the Atlantic Coast, Amer. Jour. Sci., 4th ser., Vol. II,
1896, pp. 433-447; Science, n. ser., Vol. IV, pp. 805-816.

2 Science, n. ser., Vol. IV, 1896, pp. 875-877.

3 Jbid., pp. 945-947; Vol. V, n. ser., 1897, pp. 149-152.

4 Jbid., pp. 918-922.

5 [bid, 1897, pp. 411-423.

© Monographs U. S. Geol. Surv., Vol. XX VI, Washington, 1895.

SUD resS FOR >TUDENTS.

COMPARATIVE STUDY OF PALASONTOGENY AND
PEvwicOGE NY.

CONTENTS.

Introduction.
Law of acceleration of development.
Nomenclature of stages of growth.
Palzontogeny.

Groups available.

Brachiopoda.

Crustacea.

Mollusca.

Pelecypoda.

Cephalopoda.

Method of working.

INTRODUCTION.

PALAZONTOLOGY ought to be synonymous with phylogeny, and
biology with ontogenetic study; but when most paleontologists
are content to describe species from a few characteristics of
adults, and to guess at their relationships and history, and when
many zodlogists are satisfied with basing species on color or
some other minor mark, while the life history of even most liv-
ing forms is wholly unknown, the need of higher ideals is
evident.

All modern classification is intended to be genetic and is
based on comparison of a series of adults from successive ages
of the earth, of which the present time is but anepisode. Inter-
esting and valuable investigations in phylogeny have been
made in this way, but such genealogies cannot, as a matter of
course, be more than approximate, for the geologic record itself
is incomplete, and the life record still more fragmentary. We

507

508 SIMUEDIOES. JRO SI(QLOIBIN IGS

have nowhere a uniform succession of rocks, and nowhere an
unbroken genetic series. It has been shown how often the facies
of the Pacific coast? region has changed, and how it now belonged
to one faunal region, and now to another, each great change in
faunal geography showing some physiographic revolution here
or elsewhere. Thus the local series is broken and filled in from
other regions, species being classed together because of resem-
blance, while their real relationship is unknown.

LAW OF ACCELERATION OF DEVELOPMENT.

Since the geologic record is so badly broken, and since mod-
ern faunas and floras are but the topmost branches of a tree
whose stock is only partly known, naturalists were merely grop-
ing in the dark in their efforts to get a genetic classification.
There was however a glimmer of light, although scarcely heeded.
No one man seems to have been the discoverer of the law of
acceleration of development, but like the idea of evolution, it
was in the air, and disclosed itself in various ways to the pro-
phetic vision of seekers after truth. J. F. Meckel,? a German
naturalist, seems to have been the first to give scientific expres-
sion to the biogenetic law, in his formula, ‘‘Gleichung zwischen
der Entwicklung des Embryo und der Thierreihe,” comparison of
development of the embryo with the race of animals. But Louis
Agassiz, although not the discoverer, was undoubtedly the first
to use the law as an aid in the systematic study of biology.
While he regarded the various genera, not as ancestors and
descendants, but as progressive steps in creation, still he saw the
analogy between the stages of growth of the individual and these
progressive steps. It was reserved for Alpheus Hyatt to formu-
late the law, and to strengthen theory with practical examples
based on study of Cephalopoda.’ In his later papers Professor

t Jour. GEOL., Vol. III, May-June 1895, Mesozoic Changes in the Faunal Geog-
raphy of California. J. P. SMITH.

2 Syst. Vergl. Anat., I., Theil Halle, 1821.

3A. Hyatt, Mem. Boston Soc. Nat. Hist., Vol. I, 1866-7, and Proc. Boston Soc.

Nat. Hist., Vol. I, 1866, “‘ Parallelisms of Individual and Order among the Tetrabran-
chiate Moliusks.”

PAL EONLOGLNY AND -PHVEOGENY 509

Hyatt has given a more exact and comprehensive definition of the
law of acceleration or fachygenesis: ‘‘ All modifications and varia-
tions in progressive series tend to appear first in the adolescent or
adult stages of growth, and then to be inherited in successive
descendants at earlier and earlier stages according to the law of
acceleration, until they either become embryonic, or are crowded
out of the organization, and replaced in the development by
characteristics of later origin.’’* A still more definite statement
by the same author is the following: ‘‘ The sub-stages of develop-
ment in ontogeny are the bearers of distal ancestral characters
in inverse proportion and of proximal ancestral characters in
direct proportion to their removal in time and position from the
protoconch or last embryonic stage.” * Since Hyatt’s first paper
the law has been rediscovered and renamed by Haeckel,3 ‘das
biogenetische Grundgesetz”’ and by Wirtenberger.* But these
naturalists, instead of adding anything to Hyatt’s definition,
have failed to reach its clearness and simplicity. The only real
addition that has been made is Cope’s$ idea of retardation, by
which is explained the separation in the ontogeny of the descend-
ant of characters that occurred simultaneously in the ancestor.
Cope says: ‘The acceleration in the assumption of a character,
progressing more rapidly than the same in another character,
must soon produce, in a type whose stages were once the exact
parallel of a permanent lower form, the condition of znexact
paralleism. As all the more comprehensive groups present this
relation to each other, we are compelled to believe that accelera-
tion has been the principle of their successive evolution during
the long ages of geologic time. Each type has, however, its
day of supremacy and perfection of organism, and a retrogres-
sion in these respects has succeeded. This has no doubt followed

tA. Hyatt, Smithsonian Contributions to Knowledge, No. 673, “Genesis of the
Arietidz,” Preface, p. ix.

2 Proc. Am. Phil. Soc., Vol. XXXII, No. 143, A. Hyatt, “Phylogeny of an
Acquired Characteristic,” p. 405.

3“ Morphologie der Organismen,” Vol. II; and “ Anthropogenie,” 1874.

4 Ausland, 1873, and “ Studien iiber die Stammesgeschichte der Ammoniten,” 1880.

5 Origin of the Fittest.

510 SIL GLOIOE SS I MONS SSI GIOY PIM TOS

a law the reverse of acceleration, which has been called vetarda-
tion. By the increasing slowness of the growth of the individ-
uals of a genus, and later and later assumption of the characters
of the latter, they would be successively lost.

By a proper application of the law of acceleration as defined
by Hyatt, and modified by Cope, all the facts of biology may be
explained; there is no such thing as “‘ falsification of the record.”
But as yet the law has had no great effect in classification, for
most paleontologists have not approached their work from the
biologic side, and biologists have been equally neglectful of the
results attained by paleontology. A distinguished zodlogist once
said to the writer, on being shown an ontogenetic series of
ammonites, and the conclusions reached, ‘‘It is all beautiful, but
almost too good to be true.” In paleontology it is especially
true that a naturalist may be a specialist in the fauna of one age,
and know little of that of another. Hence the animals of various
periods have been classified according to varying standards, all
artificial, The only cure for these discrepancies is study of
ontogeny, and comparison of stages of growth of the individual

yy

with ancestral genera. This will also prevent the description of
supposedly new genera and species based on immature specimens,
as has so often been done. The writer remembers once collect-
ing numerous Ceradites in the Karnic limestone of the California
Trias, much to his astonishment, for they ought not to occur so
high up. He afterwards found, however, that they were not
adults, but adolescent ceratitic stages of Avpadites ; a similar
case was the finding in the same horizon a 7zrolites above its
proper range, but it turned out to be the young of a Tvachyceras
that persisted unusually long inthe 77zvolites stage. At that time
there was nothing in the description of these genera or any of
their species to guide one, and so their ontogeny had to be worked
out independently. But there is nothing in the description of
almost any fossil genera and species to prevent just such mis-
takes, and they are constantly being made.

By careful study of ontogeny in comparison with phylogeny

* Origin of the Fittest, p. 142.

PALZONTOGENY AND PHYLOGENY S11

the paleontologist can correlate correctly fossil beds where even
all the genera and species are new; he can even prophesy con-
cerning the occurrence of unknown genera in certain horizons
when he finds their minute counterparts in youthful stages of
later forms; infact he could often furnish just as exact a descrip-
tion of the form as if he had the adult genus before him.

NOMENCLATURE OF STAGES OF GROWTH.

In order to correlate ontogenetic stages with the generic
changes seen in the development of the race it is necessary to
have an exact scientific nomenclature. The most satisfactory is
that given by Professor Hyatt in ‘‘Phylogeny of an Acquired
Characteristic.’’?

TABLE OF ONTOGENETIC STAGES.
Stages Stages Substages Comparison with phylogeny
Embryonic (1) Embryonic Protembryo |
Mesembryo |
Metembryo |

Phylembryonic |

Neoembryo [
Typembryo |
Phylembryo }

Epacme

|
Larval (2) Nepionic Ananepionic (
Metanepionic + Phylonepionic

:)

lL

Paranepionic
Adolescent (3) Neanic } Ananeanic

t
t

Metaneanic Phyloneanic
Paraneanic

Adult (4) Ephebic Anephebic
Metephebic Phylephebic

Parephebic

Acme

Senile (5) Gerontic Anagerontic
Metagerontic + Phylogerontic

Paragerontic

Parac-
me

With the embryonic stage the paleontologist can do noth-
ing, except the very last substage or phylembryo, when the
Mollusca, Brachiopoda and other groups begin to secrete their
shells; but all the later stages are easily accessible in well-
preserved material.

* Proc, Am. Phil. Soc., Vol. XXXII, No. 143, pp. 391 and 397.

512 SLOUDIES FOR STUDENTS

The best example of correlation of ontogenetic stages with
phylogeny is the genealogy of Medticottia, worked out by Kar-
pinsky,* who has shown that the Carboniferous genus Pronorites
goes through the following stages: latisellate protoconch, phyl-
embryonic; with the second suture it reaches the Anarcestes
stage, nepionic; about the end of the first revolution the
lbergiceras stage begins, paranepionic; second revolution shows
the Paraprolecanites stage, neanic; on the third whorl begins the
Pronorites stage, adult. Thus with regard to Pronorites the genus
Anarcestes is phylonepionic, /éergiceras is phyloparanepionic,
Paraprolecanites is phyloneanic. In the same work Karpinsky
has shown that Medlicotta is a direct descendant of Pronorites
and in its development goes through all the stages of the ances-
tral genus and adds several more. The first revolution of Wedh-
cottia could not be studied, but on the second revolution was
seen the /éergiceras stage, metanepionic; on the third whorl the
Paraprolecanites stage, paranepionic; at the end of the third whorl
the Pronorites stage, beginning of the neanic; on the fourth whorl
the Szcanites stage, end of the neanic: on the the fifth whorl the
Promedlicottia stage, anephebic; and lastly, at end of the fifth
whorl, Medticottia, adult in characteristics, though not yet in size.

PALASONTOGENY.

Groups available.—Vertebrates are out of the question for
this sort of work, being too highly accelerated in their develop-
ment; the stages that might be useful in phylogeny are gone
through before the animal is capable of being preserved as a
fossil. Inthe Ce@lenterata the relations between Cenozoic and
Paleozoic forms are not understood, and the ontogeny of avail-
able forms does not show stages that are striking enough to tell
much. In Echinodermata difficulty of preservation of fossil
forms makes ontogenetic study almost impossible, and recent
forms have been too little studied for any comparison of stages
of growth with ancient genera to be possible.

*Mém. Acad. Impér. Sci., St. Pétersbourg, VII Ser., Tome XXXVII, No. 2.
‘* Ammoneen der Artinsk-Stufe. ”’

PALZZONTOGENY AND PHYLOGENY Rie,

The available groups are the Brachiopoda, the Mollusca, and
the Crustacea.

Brachiopoda.—The brachiopods have this decided advantage,
that they can be hatched in marine laboratories, and the various
stages studied from the egg up, as has been done by Brooks,
Kovalevski, Lacaze-Duthiers, Morse and Shipley, with the genera
Cistella, Glottidia, Lacazella, Liothyrina, and Terebratulina. But it
was reserved for the paleontologists Beecher, J. M. Clarke, and
Schuchert to correlate the ontogeny of living forms with ances-
tral genera and give a biogenetic classification of the Lrachiopoda*
based on ontogenetic study.

In living specimens the subdivisions of the embryonic stage,
protembryo, mesembryo, neoembryo, and typembryo may easily
be made out, but since these are shell-less the work of the pale-
ontologist begins with the phylembryonic substage, when the shell
gland secretes the protegulum. From this upwards the paleon-
tologist works on equal terms with the zodlogist, for the suc-
ceeding stages are capable of preservation, and may be compared
with ancestral genera. Thus even the phylembryonic stage, or
protegulum, is represented by the Cambrian genus Paterina, the
ancestral prototype of all Lrachiopoda.

Beecher and Schuchert? have also demonstrated that the
Ancylobranchia (Terebratuloids) all go through a primitive Cen-
tronelliform stage, and that the Helicopegmata (spire-bearers) do
the same andare fora while genuine Ancylobranchta. Schuchert’s
classification of the Brachiopoda, published in Eastman’s trans-
lation of Zittel’s Text-Book of Paleontology, 1896, may be
taken as strictly biogenetic so far as the data now at hand make
such athing possible. And this is the only group of which we
have a biogenetic classification.

‘For correlation of stages of growth with generic changes, and for the literature on
ontogeny and phylogeny of Brachiopoda, see papers by Dr. C. E. Beecher, Amer. Jour.
Sci., Vol. XLIV, Aug. 1892, “ Development of Brachiopoda,” Part 2.; and Trans.

Connecticut Acad. Sci., Vol. IX, March 1893, “Revision of the Families of Loop-
bearing Brachiopoda;” and ‘“ The Development of Terebratalia Obsoleta Dall.”

2Proc. Biol. Soc. Washington, Vol. VIII, July 13, 1893, ‘* Development of the
Brachial Supports in Dielasma and Zygospira.”

514 SINGIQVIRS, SHOW, SI GHONEIN IGS

Crustacea.—The only Crustacea that are useful for the study
of paleontogeny are the trilobites, and since they are all extinct
without leaving any descendants, modern biology can give us
little help. Weare thus toa greater extent than with the Brach-
iopoda thrown entirely on the ontogeny of fossils, and in this case,
too, the various stages must be worked out from separate indi-
viduals. Many naturalists, beginning with Barrande, have worked
on the ontogeny of trilobites, have described various stages,
sometimes as larvee, sometimes as adult genera or species, but they
met with seemingly insuperable difficulties in correlating these
stages with the genealogy. Dr. C. E. Beecher, however, has
overcome these difficulties, presenting his results in a recent

yy

paper on ‘‘The Larval Stages of Trilobites,’’* in which he shows
that all trilobites go through a phylembryonic stage, protaspis,
homologous to the protonauplius of the higher Crustacea. While
no known genera are exactly like the protaspis, still there are
several that retain many of its features. After the protaspis
stage the various groups of genera develop in different directions,
but all go through larval stages analogous to generic changes in
their group. The protaspis itself of the later groups becomes
more complicated by acceleration of development, but always
retains its essential features. By means of this study Dr.
Beecher has been able to give the beginning of a truly genetic
classification of trilobites. ?

Mollusca.—Of the Mollusca only the Pelecypoda and the Ceph-
alopoda are of use to the student of paleontogeny, for the Gas-
tropoda have not been classified in a satisfactory manner, and the
larval stages even of living forms not well studied.

Pelecypoda.—Almost all that has been done in comparing
genera of Pelecypoda with stages of growth is the work of Dr. R.
T. Jackson,3 who has shown that they all go through a phylem-
bryonic stage, prodissoconch, analogous to the protegulum of

tAmer. Geol., Vol. XVI, Sept. 1895.

2 Amer. Jour. Sci., Feb. and March 1897, ‘‘Outline of a Natural Classification of
Trilobites.”

3Mem. Boston Soc. Nat. History, Vol. IV, No. 8, 1890, “Phylogeny of the Pele-
cypoda.”

PALAZZONTOGENY AND PHYLOGENY 515

Brachiopoda, the protoconch of Cephalopoda and Gastropoda, and
the protaspis of trilobites. The prodissoconch is a straight-
hinged, two-muscled, toothless, smooth-shelled, bivalve stage,
corresponding to the primitive group of Pelecypoda. Even the
monomyarian Ostrea goes through this dimyarian stage. Pro-
fessor W. H. Dall? has used this and other facts in the develop-
ment of the pelecypods, giving the most satisfactory classification
up to this time. But from the very nature of the case, when the
ontogeny of few living and no fossil forms is known, an evo-
lutionary classification of pelecypods is impossible.

Cephalopoda.—The living dibranchiate cephalopods, Octopus,
Loligo, Spirula, Argonauta and other common forms, are incapable
of preserving the larval stages as fossils. The only living tetra-
branchiate genus, Vautilus, can have its larval stages preserved as
fossils, but is one of the old unspecialized types, not having
changed greatly since the first nautilian shell, and consequently
having no striking changes in its ontogeny.

The animals that are capable of giving the best proof of
evolution are the ammonites. These branched off from the
nautiloids at the beginning of the Devonian, continued increas-
ing, diverging, became highly specialized and accelerated until
their final extinction at end of the Cretaceous. Each ammonite
goes through a larval history that is long and varied in direct
proportion to the length of time from its period back to the
Lower Devonian. Thus the Vautelinide@ are the first of the new
stock, and their ontogeny is comparatively simple, there being
no great changes from the larval up to the adult stages. The
higher Devonian and Carboniferous forms go through several
generic changes before they become adults, and the Mesozoic
genera have still longer larval and adolescent periods, that 1s,
longer in the sense of more complicated.

From the work of L. von Buch, Quenstedt, and others of the
older paleontologists the increasing variety of forms from the
goniatites of the Paleozoic to the ammonites of the Mesozoic

*Pelecypoda, Text-book of Paleontology, kK. A. VON ZITTEL, Revised English
Edition, Vol. I, Part 1. Macmillan & Co., 1896.

516 SL QWOIIES SHOU, iS) H(QYOVIIN TGS

was known long ago; these naturalists knew, too, that ammon-
ites went through a goniatite stage of growth, without connect-
ing this with evolution. By using their work we can get a com-
prehensive view of the development of ammonoids from the
most primitive goniatites to the most highly developed ammon-
ites, and thus construct a tentative family tree.

The simple primitive forms of the Lower Devonian branch
out by the end of that age into two distinct stocks, the Prole-
canitide and the Goniatitide, mostly low whorled, involute, with
simple sutures and little ornamentation. Before the end of the
Carboniferous some genera have already become ammonitic in
the digitation of their sutures, as Popanoceras, Thalassoceras,
Pronorites, and some have taken on ammonitic ornamentation of
the shell, while the sutures remain simple and entire, as Gastrio-
ceras. None of these forms, however, are very evolute, and
the whorls are mostly rather low. In the Permian Pronorites
and its descendants Stcanites and Medlcottia play an important
part, Arcestide are already become important members of the
fauna, the 7ropitide are just beginning, while the Glyphioceratide
are dying out. Some few genera still persist in the gontiatitic
stage, but most of them became ammonitic before the Trias was
well on.

In the Trias the important groups are Arcestide, Pinacocera-
tide, Tropitide, Ceratitide, with numerous others less impor-
tant as members of the Triassic fauna, but of great interest as
ancestors of many of the chief families of the Jura and Creta-
ceous. In the Jura these ammonites reached their acmre,
branching out into very many families and subfamilies, increas-
ing usually in complexity of sutures and variety of ornamenta-
tion. Inthe Cretaceous they gradually declined, dropping off
one at a time until all were gone. The total number of Ammon-
oidea now described reaches about 5000, of which only a few
hundred belong to the Palzozoic goniatites, the others belong-
ing to the ammonites of the Carboniferous, Permian, and Meso-
zoic. Later than this no ammonoids are known.

Only simple radicles or stocks persist, but from time to time

PALAZAONTOGENY AND PHYLOGENY S17

certain genera branch off from the main stock, become highly
specialized, and often give rise to so-called abnormal’ forms,
such as Hamutes, Baculites, Crioceras, Scaphites, phylogerontic or
_ degenerate genera, which do not perpetuate their race. These
do not form a natural group, but are themselves even in some
cases polyphyletic, as shown by their ontogeny; so far as exam-
ined their larval stages all correspond to various normal genera.

Of course there were phylogerontic genera that were not
abnormal in shape; thus Clymenia branched off in the Upper
Devonian into a variety of species, and disappeared as suddenly;
Medhicottia reached its culmination in the Permian, barely man-
aged to live on until the Trias, and disappeared without pos-
terity, while the main stock of unspecialized Prolecamtide
endured as long as the race. The number of phylogerontic
forms increases in the Mesozoic, showing a constantly increas-
ing tendency to become abnormal, until before the end of the
Cretaceous the entire race of ammonoids becomes phylogerontic,
and dies out from sheer lack of plasticity to modify itself further
with changing conditions.

Such a general view or family tree of the ammonoids may
be seen in any of the text-books of paleontology, especially
those of Steinmann,? and of K. von Zittel,3 where we get the
best attempts to represent our present knowledge and ideas of
the genetic relationships of ammonites. These genealogies are,
however, purely tentative, based not on ontogeny but on com-
parison of series of adults. This would undoubtedly be the
safest way if we had a perfect series of genera and species, but
such a thing is unknown, and can never be obtained, on account
of the incompleteness of the geologic record, and the mixing of
faunas by migration in the past.

The researches of Hyatt, Branco, and Karpinsky have given
us a surer way; from their work we have learned that the
Ammonoidea preserve in each individual a complete record of

tJ. F. Pompecky, Ueber Ammonoideen mit Anormaler Wohnkammer. Stuttgart,
1894.

? Elemente der Palzontologie. 1890. 3 Grundziige der Palzeontologie. 1895.

518 SLUDIES HOR SLODENTS

their larval and adolescent history, the protoconch and early
chambers being enveloped and protected by later stages of the
shell. And by breaking off the outer chambers the naturalist
can in effect cause the shell to repeat its life history in inverse
order, for each stage of growth represents some extinct ances-
tral genus. These genera appeared in the exact order of their
minute imitations in the larval history of their descendants, and
by a comparative study of larval stages with adult forms the
naturalist finds the key to relationships, and is enabled to
arrange genera in genetic series. They were all marine, never
parasitic, and so with them there is no obscuring of the record;
also in the Mollusca generic and specific characters show in the
shell better than in the soft parts; so the classification of fossil
ammonites is just as good as that of living shellfish.

Although genera appeared in the order of corresponding
larval stages, they did not disappear in the same order; and so
their survival under favorable conditions is liable to make con-
fusion in the record, if one depends wholly on the study of
series of adults. Such forms, for instance, as Styrites, Tropicel-
tates, Miltites and others that are now known only in the Karnic
zone of the Upper Trias are undoubtedly such survivals, for they
still have simple goniatitic sutures, very little ornamentation,
and in general are more like Lower Triassic ammonites than
members of the Zvopites subbullatus fauna. The stray Tzrolites
foliaceus, which appears in the Alps and in California in this
same fauna, is another survival of a Lower Triassic type, but for-
tunately we do know 7Z7rolites in the horizon where it belongs.
If this were not the case the naturalist would be very much puz-
zled at finding 7rachyceras of the Karnic horizon going through
a Lirolites stage in its early youth.

One great drawback to this work is that the ammonite faunas
of the various ages have been classified by different specialists
and on different principles, but all artificial. Thus the Triassic
ammonites are divided into Leiostraca (smooth shelled), and
Trachyostraca (rough shelled), a classification that cannot be
extended even to Jurassic groups. The Trachyostraca are fur-

PALAtONTOGENY AND PHYLOGENY 519

ther divided into Zvop:tide, with long body chamber, and Cera-
titide, with short chamber. But neither of these groups is mon-
ophyletic, for it is quite probable, judging from their ontogeny,
that members of both groups are derived from the Gomattide,
and others from the Prolecanitide. Further, the authorities agree
in deriving the 7vopitide from the Glyphtoceratide, but the larval
stages of some of the Zvopfittde show the undivided ventral
lobe and an unmistakable resemblance to certain Prolecanitide ;
other so-called Tvopitid@ show the divided ventral lobe at an
early age, and a decided resemblance to the stock of Glyphio-
ceratide.

Inthe same way most authorities agree that the Trachyostraca
were all extinguished at end of the Trias, and that all the Juras-
sic and Cretaceous ammonites, with the exception of Lytoceratide
and Phylloceratide, were derived from the radicle Pszloceras, and
this, too, in spite of the fact that many of the genera are rough
shelled, and in their larval stages show marked likeness to trach-
yostracan genera. Any naturalist can convince himself of this by
looking at the young stages of Jurassic ammonites figured by
Quenstedt.* Quite recently Professor W. Waagen?’ has called
attention to the likeness of certain Trachyostraca to Jurassic
genera, and indicated the probability of genetic relationships.
But Mojsisovics3 says that these similarities have nothing to
do with relationship, but are purely ‘‘convergence phenomena,”
whatever that may mean. Resemblance of adults of Triassic
and Jurassic forms might with some reason be ascribed to this
mysterious agency, but surely no biologist would thus explain
away the resemblance of larval and adolescent stages of Juras-
sic ammonites to adult Trachyostraca of the Trias. There
was some excuse for such opinions as long as the fauna of
the upper Trias was not well known, and there was apparently
a ereat, break in the Series, of ammonites. But -after the
appearance of the monographs of G. von Arthaber, Diener,

tAmmoniten des Schwabischen Jura.

? Pal. Indica, Salt Range Fossils, Vol. II, p. 122.

3 Das Gebirge um Hallstadt, Bd. II, p. 265.

520 STUDIES FOR STUDENTS

Mojsisovics and Waagen,’ on the Triassic faunas of the Alps,
Himalayas, the Salt Range of India, and Siberia, there is no
longer any such excuse. Ancestral types, long predicted by
larval stages of Jurassic ammonites, may be seen in these
works, as, for instance, 7vopiceltites, which is exactly like the
neanic stage of Amaltheus; but the great variety is confusing,
and correlation difficult, on account of unsatisfactory classifica-
tion.

The only solution of the problem is to classify genetically
the Paleozoic goniatites, and from them work upwards into the
Permian and Lower Triassic ammonites. These older groups
have simpler larval stages, are not very greatly accelerated, and
repeat clearly their ancestral history. When this is done the
radicles will all be known, and when we know the stock of
the tree, the branches that came off in the higher Trias, Jura,
and Cretaceous will offer no difficulties. The most systematic
attempt to do this is Haug’s paper, ‘‘ Les Ammonites du Permien
et du Trias;’’* but his classification is based wholly on the char-
acter of the sutures, and neglects other characters, such as
sculpture and shape of the whorls. Thus Haug’ places Lutom-
oceras with the prionidian family Zvachyceratide, disregarding
its ontogeny, which places it undoubtedly with the 77vopztide.
But no classification based entirely on one character can be
truly genetic. Hyatt* in his monographs on the ontogeny of
ammonites has shown us the way; Branco by his studies of the
larval stages of ammonoids has accumulated a great mass of
accurate data that can be used with confidence even by the student
that rejects his theories as to classification. And Karpinsky, by
using the methods and principles discovered by these naturalists,
has worked out the genealogy of one of the chief stocks of the
earlier ammonites.

1 For the literature on’ Triassic faunas see JoUR. GEOL., Vol. IV, No. 4, J. P.
SmirH, “ Classification of Marine Trias.”

2 Bull. Soc. Géol. France, II Ser., Vol. XXII. 1894, No. 6.

3Op. cit., p. 408.

4Bull. Mus. Comp. Zool., Vol. III, No. 5, 1872; and Smithsonian Contrib. to
Knowledge, “Genesis of the Arietidae,”’ and other papers.

PALAZFONTOGENY AND PHYLOGENY 521

This way lies the truth, and not in groundless speculations
such as many students of cephalopods are prone to indulge in.

Method of working.—In order to succeed, one must select
material with great care, preferably limestone that is soft but
not so weathered as to crumble, nor so brittle as to shatter.
One’s finger nail and some steel dental chisels are all the tools
needed for breaking off the outer whorls of young ammonites. A
microscope with thirty diameters magnifying power is the most
satisfactory, although higher powers are occasionally needed.
For studying surface markings a strong pocket lens is usually
sufficient; the specimen should then be placed dry on white
cardboard. For observing the sutures, or shape of the whorls,
the specimen should be placed on cardboard in a drop of water,
spread out so as not to distort the object. The water, being
slightly viscous, will also hold the small object in any position.
For taking measurements a micrometer eyepiece is needed,
especially in drawing, for the camera lucida is not very satisfactory
for drawing opaque objects. Sections can easily be cut by
grinding with emery powder on a glass plate.

The accompanying illustrations will give an idea of how the
facts are ascertained. A number of well-preserved adults of a
species are selected, and the outer coils are pulled off piece at a
time under water, until a complete series is obtained, represent-
ing every change .in growth. All the pieces of whorls are pre-
served, but often it is possible to have a complete series in one
specimen. The individuals representing stages of growth are
kept separate, in small glass tubes attached to cards for labels,
on which are noted the measurements of the specimen, stage of
growth, and such other facts as are wanted for ready reference.

On plate A are shown the results of some work of this char-
acter. The species selected was Schloenbachia aff. chicoensts
Trask, from the upper Horsetown beds, top of Lower Creta-
ceous, from Phcenix, Oregon. Fig. 1 shows the protoconch with
part of the first whorl drawn as if unrolled. The protoconch is
phylembryonic, representing the primitive ammonoid; the first
suture, angustisellate, with narrow lateral lobes and saddles, is

STUDIES FOR STUDENTS

522

PALAZONTOGENY AND PHYLOGENY 523

ananepionic; the second suture with the abdominal lobe is meta-
nepionic, and represents the ammonoid radicle Anarcestes; the
third and fourth sutures correspond to Jornoceras and Prionoceras ;
the fifth suture is*a transition from Prionoceras to Glyphioceras ;
and the sixth with the divided ventral lobe represents Glyphuoceras.

Fig. 2 shows the larval stage, at diameter of 0™”.68, three-
fourths of the first whorl. It has a low broad involute whorl,
with divided ventral lobe, one lateral lobe, and another on the
umbilical border. This stage is paranepionic, and is like the
older species of Glyphioceras.

Fig. 3 shows the development of the sutures from the third
to the tenth, on a specimen of diameter 0™™.64.

Fig. 4 shows the advanced Glyphioceras stage, with lobes and
saddles, well developed, at diameter of 1™™.20; the second lat-
eral lobe already begins to show on the umbilical shoulder.
This stage is transitional to Gastrioceras.

Fig. 5 shows the end of the paranepionic stage, correspond-
ing to Paralegoceras, at 2™.25 diameter; the umbilicus widens,
the whorls become higher and narrower, and a third lateral lobe
appears on the umbilical border. The sutures still remain goni-
atitic, but in the next stage, ananeanic, ammonitic ornamenta-
tion, in the shape of a keel, appears at 2™™.70; and at 3™™.20
diameter the first lateral saddle becomes indented, and the
adolescent stage is well along.

Fig. 6 shows a cross section through the center, diameter
6™™".25, four whorls, paraneanic. The inner whorls are low and
broad, and the later ones become successively higher and _ nar-
rower in proportion.

Fig. 7 shows a section through the protoconch, diameter
22™™ 2c, six whorls, adult stage; the relative increase of height
of the whorls and the squaring of the abdominal shoulder is’
quite marked as the adult stage advances.

On these figures may be seen increase in number of lobes and
saddles, change in position of the siphon from median to exter-
nal, and the development of the whorls, in height, width, and
involution.

524 SHODIES OK SHMIDEN DS

By following this method on suitable material the complete
ontogeny of any species may be worked out. In order to work
out the phylogeny of any form it is necessary to combine this
with comparative study of antecedent genera and species. When
this is done for all the Ammonodea, their genealogy will be more
perfectly known than any other family tree possibly can be.

JIL ANAS, 413

Fic. 1. Protoconch of Schloenbachia, showing the first six sutures of the
attached coil. Enlarged thirty times.

Fic. 2. Larval stage of Schloenbachia, diameter o™™.68; thirty times
enlarged ; three-fourths of first whorl. 2a, side view; 20, front view.

Fic. 3. Larval stage of Schloenbachia, diameter o™".64; thirty times
enlarged. Showing sutures from the third to the tenth. From above.

Fic. 4. Larval stage of Schloenbachia, diameter 1™™.20; fifteen times
enlarged. One anda half whorls. 4a, front view; 44, side view.

Fig. 5. End of larval stage of Schloenbachia, diameter 2™™.25 ; fifteen
times enlarged. Paralegoceras stage. 5a, side view; 50, front view.

Fic. 6. Cross section of Schloenbachia, diameter 6™™.25; fifteen times
enlarged; four whorls. Adolescent stage. The protoconch is seen in the
center P.

Fig. 7. Cross section of Schloenbachia, 22™™.25; three and a half times
enlarged; six whorls. Adult stage.

JAMES PERRIN SMITH.
STANFORD UNIVERSITY,
California.

EDITORIAL.

THE press announce the auspicious starting of Andrée on
July 11. The result of this first experiment in Arctic aérial
navigation will be awaited with unusual interest. If Andrée
shall succeed in floating at a suitable elevation for even a week
and shall make good his return, he can scarcely fail to bring
back data of vital importance. It is of trivial consequence
whether he passes near the pole or not, and his geographical
discoveries are uncertain, for his course may not take him over
new territory, but he will determine the course pursued by the
body of air in which he floats if he is able to keep his location,
of which there is little ground for question. The course pur-
sued by a given body of air in a region which bears such critical
relations to the whole system of atmospheric circulation is a
matter of radical importance. Observers at fixed points upon
the earth can only determine the transient local direction of
passing bodies of air. They cannot directly demonstrate the
actual circulation. They can only infer it from a combination
of local observations. But the actual circulation can be dete1-
mined by means of the balloon floating with the body of air,
subject, of course, to certain obvious qualifications, particularly
those that relate to vertical movements. Andrée’s trip should
therefore bring forth data of vital consequence to all hypotheses
relating to polar atmospheric circulation. Among these hypoth-
eses is one suggested by the ice drift which the writer has never
seen in print, and which pointedly illustrates the possible value
of Andrée’s experiment.

It is now well known that the free ice off the Siberian coast
drifts westward until it impinges upon the east coast of Green-
land, when it is diverted to the south, but on reaching Cape

525

526 EDITORIAL

Farewell it rounds to the westward and even northward, until it
is again arrested by Baffin Land and the American mainland,
and forced southward. The marvelous trip of Nansen has given
this a heroic demonstration not likely to be questioned. It is
also known that the ice fields north of Greenland and Grinnell
Land press hard against the coast, and crowd through the straits
between these lands in a southwesterly direction. It is also
known that the ice presses hard on the north side of the Parry
Islands and pushes southward and eastward, effectually block-
ing all the straits between them as well as Jones Sound on the
east. It is also known that Banks strait and McClintock chan-
nel, trending from the northwest to the southeast, are effectually
blocked by the persistent jam of the ice crowding in from the
northwest. It is the strong and unremitting jam of ice into this
channel that has rendered all attempts at the northwest passage
abortive. Correlating these movements, it appears that there is
a common drift towards some point not far distant from the
magnetic pole.

Now it is well recognized that this ice drift is essentially con-
trolled by the winds. The sea currents are, to be sure, a factor,
but, except as they are an expression of wind action, they seem
to be relatively ineffectual. These movements have therefore
suggested the hypothesis that the pole of the winds is not identi-
cal with the pole of the earth, but lies somewhere in the quarter
toward which the ice drift tends to concentrate itself. This is
based on the assumption that the supposed spiral course of the
winds about the atmospheric pole tends to concentrate the ice
at it. It is not difficult to find data in lower latitudes that fall
in with this hypothesis, as, for instance, the predominant course
of mid-latitude cyclones in this country and the trend of the
Asiatic arid belts.

This is not the place to argue the hypothesis nor to set forth
the numerous and important corollaries that spring from it. A
sufficient number of significant corollaries will doubtless suggest
themselves to indicate its importance, 2févwe. The purpose in
' hand is to show how decisive the determination of the course

EDITORIAL #27

of any representative body of air in those regions must be on
such a hypothesis and on similar hypotheses. If Andrée’s
balloon follows a spiral course (cyclonic gyrations aside) whose
center lies in the quarter toward which the ice concentrates,
the hypothesis will receive encouragement. If not, it becomes
a hopeful candidate for the limbo of unsupported inferences.
The reverse may be said respecting the common assumption
of astrictly axial whirl, but as that rests on general probabilities
it does not so well illustrate the critical value of an actual test of
the movement of the air.

On quite other grounds it might equally well be affirmed that
the navigation of the Arctic air by balloons will, if found practi-
cable, have its own peculiar function which neither ship nor
sledge can supply. ee:

*

THE state of Missouri has recently had deep disgrace thrust
upon it by the removal of the efficient director of the Geological
Survey and by the appointment of men to its care and conduct
who possess, according to information that we deem trust-
worthy, not only no competency to perform their duties, but
not even a plausible semblance of competency. These appoint-
ments have apparently no other motive than the conferring of
personal or political favors. No causes of complaint, we are
informed, were even alleged against the previous conduct of the
Survey or against the officials in charge of it. The scientific
public has had ample demonstration of the vigor and energy
with which the Survey has been prosecuted, the promptness
with which its results have been published, and the adaptation
of the work to the development of the economic as well as sci-
entific resources of the state. It appears, therefore, that the
moneys appropriated by the state of Missouri for the laudable
purpose of investigating and advertising its resources and of
informing its people concerning their own sources of material
and intellectual wealth are being virtually diverted from the
purposes specifically indicated by the statute of the state, and
are being used for the personal and political interests of the

528 EDITORIAL

governor and his friends in the form of payment for worthless
services. We are not sufficiently informed in the technicalities
of law and the processes of the courts to know how legal action
in a case of this kind can be instituted and maintained, but if
the appointees are as obviously incompetent as information
indicates, they are simply consuming the funds of the state to
no purpose save their own, and we think that an effort should
be made to procure a formal declaration by the courts whether
this is not a virtual embezzlement, and if so, to secure the award
of the proper punishment. If there is now no way of compel-
ling a governor to respect the laws of a state and the purposes
of its statutes, a way should be provided. Le :Caet

REVIEWS.

The bedford Oolitic Limestone of Indiana. By T. C. Hopxrns and
C. E. SIEBENTHAL. Extr. 21st Ann. Rep. Dept. of Geology
and Natural Resources (of Indiana). W. S. Blatchley,
State Geologist, Indganapolis, 1896.

All of the older geological maps of Indiana show the various rocks
across that state in broad, sweeping lines, and that, too, in spite of the
fact that the rocks are everywhere nearly horizontal and have been
deeply trenched by the streams. ‘The last two reports of State Geolo-
gist Blatchley have shown a great improvement in this respect—the
maps by Hopkins and by Kindle in the twentieth report and those by
Hopkins and Siebenthal in the twenty-first report are by far the best
that have yet appeared of the areas represented, showing, as they do,
the dendritic form of ‘outcrop to be expected.

From the earliest to the latest of the Indiana reports, almost every
one has had something to say of the well-known odlitic limestone ;
but hitherto there has been no report on this rock that could lay
claim to being a systematic description and discussion of it. The
present report bears internal evidence of having been prepared under
pressure, but it is nevertheless a highly creditable and valuable piece of
work, and by far the best report ever made on the Bedford stone. The
maps show a vast amount of field work, and exhibit for the first time
the distribution of this valuable building stone. We are glad to see
that the authors do not feel it incumbent upon themselves to ‘ puff”
the Bedford stone. This and every other good building stone, once
it is given a chance, may be trusted to take care of its own reputation
without any such help from geologists as that quoted on page 323.
Evidently some people think the truth can be improved upon. What
Mr. Hopkins says is certainly as much as reasonable people can ask.
“The Bedford oGlitic limestone can unhesitatingly be recommended as
one of the most durable building stones on the market, where not
exposed to the action of acids. It is fireproof up to the point of cal-

529

530 REVIEWS

cination, in which property it can be surpassed by no other limestone
and but few other building stones, as very few are absolutely fire-
proof.” The list of the more important buildings made of the odlitic
limestone at the end of the report shows that it is already used in
almost every state of the Union, in which use the cities of Chicago,
Indianapolis, and New York lead.

Statistics show that over six million cubic feet of Bedford stone
was quarried in 1895, worth more than a million and a half of dollars ;
1784 men were employed that year in the quarries, to say nothing of
those engaged in stone-cutting, transportation, and building. ‘The
work includes valuable statistics, tests, and analyses, and many
instructive photographs of quarries, machinery, exposures, and build-
ings, and closes with a bibliography of oGdlites in general and of the
Bedford stone in particular.

In the way of minor criticisms abandoned quarries are indicated on
the maps, but not those in operation; while the lithographing of the
maps is neatly done, the distinctions between formations might have
been clearer in some cases without increasing the cost of the maps.

The most serious criticism of the report is one for which the
authors are not responsible, but it is one that unfortunately applies to
many of our state reports, and is referred to here rather on general
principles than on account of it being especially applicable to the
present case; we refer to the short time allowed for its preparation.
No matter what the worker’s aims, intentions, or abilities may be,
behind him is the state geologist demanding much work in a short
time and at little expense; the state geologist imagines the legislature
is making the same demands on himself, while behind the legislature
are the people asking for practical results. In our national surveys we
have pretty much the same state of affairs—a constant demand for
something to show for the money used. As a matter of fact, the prac-
tical results of hasty work cannot be the best results. Haste in work
of this kind, like haste in other things, is waste. It is our decided
opinion that no member of a legislature or of Congress will object to
allowing a state or a national geologist time to do good work if only
the truth is placed fairly before him. Last year we had a valuable paper
by Professor Hopkins on the carboniferous sandstones of Western Indi-
ana; this year we have the present report on the Bedford stone, and
some other year we shall have reports on other building materials of
Indiana. Thus the matter that ought to have formed a single mono-

REVIEWS 531

graph is scattered through several volumes, disconnected, and there-
fore less known and less valuable either to the state or to the general
public. Nevertheless, the state geologist is to be congratulated on his
selection of men to do this work and on the results obtained in so short
atime, for it is unquestionably one of the very best reports made in
this country upon building stones. J. C. BRANNER.

The Ancient Volcanoes of Great Britain. By SiR ARCHIBALD
Gekiz~ee. ok. Ss: Macmillan & Co, London and New
York, 1807.

This work, as Sir Archibald Geike states in the introduction, is the out-
growth of his presidential addresses before the Geological Society of Lon-
don in which he sketched the volcanic action in ancient times in Great
Britain, whose record is left in the igneous rocks of several epochs from
pre-Cambrian to Tertiary. No other part of the earth, so far as now
known, presents within a comparatively small area such evidences of
oft repeated volcanic action through so great a period of time. Com-
mencing in pre-Cambrian times with three definitely localized volca-
noes, the series is found to have extended through the Cambrian, Silur-
ian, Devonian, Carboniferous, Permian and Tertiary times. The impor-
tance of the evidence furnished by so extensive a series of periods of
volcanic activity as to the cause of volcanic action, and the source of
the materials erupted must be apparent.

Its bearing on the question as to whether volcanic phenomena dif-
fered materially in the earlier periods of geological history from those
of recent date, is also most valuable. And it is to be noted that the
conclusion reached is that they arealike. The presentation of the facts
known about these ancient volcanoes involves a description of rocks
that were formed in various situations in the volcanoes ; upon their sur-
face, within their mass or within rocks beneath or about them; and
which were subjected during the ages to processes that have modified
their internal character and sometimes their external form. In order
that these descriptions may be understood by the general reader the
first chapters of the work are devoted to a consideration of general
principles and methods of investigation. The nature and causes of vol-
canic action, and the phenomena connected with modern volcanoes are
briefly noted. Considerable space is given to the characteristics of

BR REVIEWS

Ancient volcanoes, the nature of the material erupted, and the several
types of volcanoes. Underground phases of volcanic action are also
described ; and the effects of subsequent denudation in exposing the
rocks and their influence on the topography and scenery are discussed.

The major part of the work treats in detail of the volcanic phenom-
ena connected with each period of activity, beginning with that in the
pre-Cambfian time. Upon petrographical grounds the most ancient
Lewisian gneiss, corresponding to what is often called Archean, is
considered to have been originally a mass of various eruptive rocks.
Although they have been subjected to great mechanical deform-
ation, the present banded structures are connected with the original
igneous condition of the rocks. They were probably underground
lavas, possibly connected with extrusive bodies. With these rocks are
associated dikes of basic and acid rocks. Rocks of volcanic origin
undoubtedly occur in the Dalradian schists of Scotland and in the
gneisses and schists of Anglesey. The Uriconian, Malvern, and Charn-
wood Forest volcanic rocks are all of pre-Cambrian age. The volcanoes
of Cambrian time occurred in South Wales, North Wales, Malvern Hills,
and Warwickshire; those of Silurian time occurred in Wales, North of
England and in Scotland, and Ireland ; partly in the Lower, partly in
the Upper Silurian. Volcanic activity was pronounced in Middle
Devonian times but in certain districts extended into the Upper Devo-
nian. Inthe period of the Old Red Sandstone there existed numer-
ous centers of volcanic activity. In Lower Old Red Sandstone time
they extended from Shetland to the Chevoit Hills in England and even
to Lake Killarney, and from the coast of Berwickshire on the North
Sea to near Lough Erne in the north of Ireland. They are less numer-
ous in Upper Old Red Sandstone time, occurring in the southwest of
Ireland and the north of Scotland. The Carboniferous age was
marked by prolonged volcanic activity in Scotland and by restricted
activity in England and Ireland. ‘The volcanoes were partly of the
plateau, partly of the puy type, accompanied, of course, by intrusive
bodies. The Permian volcanoes of Scotland and England are much
less important.

Four fifths of the second volume are devoted to the volcanoes of
Tertiary time, for the reason that they are the most recent and their
rocks are the freshest and most abundant. They occur along the west
coast of Scotland and the northeast of Ireland. ‘The dikes, plateau, and
fragmental rocks are described in detail, and an account of the mod-

BOOK REVIEWS 533

ern volcanoes of Iceland is introduced by way of illustration. ‘The
eruptive vents and the intrusive bodies, as sills and bases, both basic
and acid, are also described.

The work closes with an account of the subsidences and disloca-
tions of the plateaux and the effect of denudations. ‘The final chapter
consists of a brief summary together with the following general deduc-
tions: The distribution of the centers of volcanic activity has been along
the western side of the country in a north and south line. ‘The per-
sistency of volcanic activity in this region and its restriction to particu-
lar localities are some of its most marked features. ‘The sites of volcanic
vents in Britain do not seem to have been determined by any obvious
structures in the rocks now visible. Volcanic phenomena cannot be
regarded as mere isolated and incidental features in the physics of the
globe. ‘They are intimately connected with profound terrestrial move-
ments. They have been essentially uniform since the beginnings of
geological time. In extent and rigor the earliest eruptions of which
we have records did not differ in any important respect from those of
the present time. However volcanic energy has not manifested itself
uniformly throughout geological time. There have been periods of
maximum and of minimum effectiveness. The character of the vol-
canic rocks and the general sequence of their eruption have been the
same with slight modification for all the periods of activity in this
region. Jo- Pp DINes;

The Submerged Valleys of the Coast of Califorma, U. S. A., and of
Lower California, Mexico. GEORGE Davipson, A.M., Pu.D.,
Sc.D. (Member of the National Academy of Sciences,
etc) coc. Calinncad «Scr, Vhird Semes, Geology, Vol: 1,
No. 2. With Nine Plates. San Francisco, 1897.

This paper gives a brief description of the Pacific coast from the
southern extremity of Lower California to the Strait of Fuca. The
general character of the coast, south of Cape Mendocino, is bold and
rocky, reaching considerable elevations within a few miles of the shore.
These coastal ranges are broken by valleys and plains of varying width
which may or may not correspond to the submarine depressions des-
cribed.

Bordering the coast from about Cape Mendocino southward there is
generally a submarine platform, having an average width of ten miles,

534 REVIEWS

and extending to the 1oo-fathom curve. Beyond this platform the
descent is usually rapid, 2000 fathoms being reached in from 35 to 100
miles from the shore.

In this 100-fathom platform the submarine valleys are found, head-
ing either close to the shore or only a short distance out, and extend-
ing to a depth of from about 100 to at least 600 fathoms. These
valleys vary largely in direction, form, and character of the bottom.
Four valleys are found off the coast of Lower California and seventeen
are described from the California coast. They are most numerous
near the southern end of the state, and near Cape Mendocino, where
four of considerable size are found within a stretch of twenty miles.
These four are peculiar in heading under the highest parts of this strip
of coast, while the majority of the channels are opposite valleys or
openings in the coast ranges. All of the valleys are described in some
detail and are well shown by submarine contours on the accompany-
ing maps. North of Cape Mendocino no submarine valleys have been
noted with the exception of one indicated near the mouth of the
Columbia River.

Although this paper is of importance to geologists, no direct attempt
is made in it to give the geological bearing of the facts stated. One
assumption, which is open to criticism, is made by the author in using
the term ‘‘submerged” where he formerly used “submarine,” to
describe these valleys, since it is doubtful whether all of them can be
considered as submerged channels. ‘The studies of the present writer
on the submarine topography of a part of the California coast have led
him to the conclusion that no general statement can be made as to the
origin of these valleys. They may be due to one or more of three
causes — either (1) they are structural, due to faulting or folding; or
(2) they are due to the forces of subaérial erosion, and therefore are
strictly ‘‘submerged valleys ;’’ or (3) they may possibly be due to sub-
aqueous erosion in delta deposits. Under which of these heads a
given valley should be placed must be determined by a special study
not only of the submarine features but of the topography, stratigraphy

?

and structure of the neighboring land area, and possibly also of the
characters of the shore-currents at that point.
W.S. TANGIER SMITH.

—

TECENT Ue UBLICATIONS.

Abhandlungen zur Geologischen Specialkarte von Elsass-Lothringen.
Band V. Heft V. J/é:d, Heft VI. Strassburg, 1897.

—ANDERSSON, J. G., Till Fragan om de Baltiska Postarkaisk Eruptivens
Alder. Stockholm, 1896.
Annales de la Real Academia de Ciencias Medicas, Fisicas, y Naturales
de la Habana. Revisita Cientifica. Entrega 390, Havana, 1897.
—Batn, H. F., Relations of the Wisconsin and Kansan Drift Sheets in
Central Iowa and Related Phenomena. A dissertation presented to
the Faculty of Arts, Literature and Science of the University of Chi-
cago in candidacy for the degree of Doctor of Philosophy. University
of Chicago, 1897.

—BARzour, Erwin H., History of the Discovery and Report of Progress
in the Study of Daemonelix.

— BIGELOW, FRANK H., Storms, Storm Tracks and Weather Forecasting
U.S. Dept. of Agriculture, Weather Bureau, 1897.

—CLARK, W.B., Upper Cretaceous Formations of New Jersey, Delaware
and Maryland. Bulletin Geol. Society of America, Vol. VIII, pp. 315—
358, pls. 40-50.

—COHEN, E. and W. DEEcKE, Uber Geschiebe aus Neu-Vorpommern und
Riigen. Berlin, 1896.

Davenport Academy of Sciences, Proceedings, Vol. VI, 1896-7. Daven-
port, Ia., 1897.

—Emmons, F. S., The Geology of Government Explorations. Presidential
Address Geological Society of Washington, December 1896.

—FAIRCHILD, H. L., Proceedings of the Ninth Annual Meeting G. S.A.
held at Washington, December 29, 30 and 31, 1896. Bulletin Geol.
Soc. America, Vol. VIII, pp. 359-446, pl. 51.

Geographical Society of Philadelphia. Map of the Arctic Regions com-
prising the most Recent Explorations of Robert E. Peary, F. Nansen
and F. Jackson, by Angelo Heilprin (drawn by J. W. Ross).

Geological Survey of Canada.

Annual Report New Series, Vol. VIII, 1895 and accompanying maps.

535

536 SSR OIIIN TG, PUBLICATIONS

Part D, Ann. Rept., Vol. VIII, Report on the Country between Athabasca
Lake and Churchill River, by J. BURR TyRRELL, assisted by D. B.
DOWLING.

Part R, Am. Rept., Vol. VIII, Report of the Section of Chemistry and
Minerology, by G. C. Hoffman.

Geological and Topographical Map of the Northern Part of the Lake of
the Woods and Adjacent Country—Part C. C., Vol. I, New Series,
1885. Ottawa, 1897.

—HALttL, C. W., The Conservation of Government Energy through Educa-
tion and Research. From the Proceedings of the Society for the Pro-
motion of Engineering Education, Vol. IV.

—HAFTET, TJUGUFEMTE. Meddelander fran Industristyrelsen i Finland,
Helsingfors, 1896.

—Hircucock, C. H., The Eastern Lobe of the Ice Sheet. American
Geologist, Vol. XX, July 1897.

—Ho.meEs, W. H., Archeological Studies Among the Ancient Cities of
Mexico, Part II. Field Columbian Museum, Chicago, 1897.

—Hopkins, T.C., The Building Materials of Pennsylvania. J.—Brown-
stones. Appendix to Annual Report of State College, Pa., 1896.

—HAvER Von, DR. FRANZ RITTER. Annalen des K.K. Naturhistor-
ischen Hofmuseums. Band XI. Nr. 3-4. Wien, 18096.
Hydrographic Office., Pilot Charts of the North Atlantic and North
Pacific Oceans, J. E. Craig, U.S. N. Hydrographer, Washington, 1897.
Imperial Survey of Japan. Catalogue of Articles and Analytical Results
of the Specimens of Soils Exhibited at the Seventh International Geo-
logical Congress, St. Petersburg, Russia. Tokyo, 1897.

—lInstituto Geoldgico de México.— Boletin Nums. 4, 5, y 6, 269 pp., map.
Mexico, 1897.

Journal of School Geography, Vol. I, No. 5. New York, 1897.
Jahresbericht der Kgl. Ung. Geologischen Anstalt Fiir 1893; Budapest,
1895.

—JENTSCH, ALFRED, Das Interglacial bei Marienburg und Dirschau Geo-
logischen Landesanstalt. Berlin, 1896. Neue Gesteins-Aufschlusse
in Ost- und Westpreussen 1893-1895. Geologischen Landesanstalt,
Berlin, 1897.

—Kansas Board of Irrigation Survey and Experiment. Report for 1895
and 1896, 237 pp., 24 pl. Topeka, 1897.

Kansas University Quarterly, Vol. VI, No. 2, 1897.

—KUMMEL, H.B., The Newark System, Report of Progress. From the

Report of the State Geologist of New Jersey, 1896.

RECENT PUBLICATIONS Sai

—LEVERETT, FRANK. Soils of [llinois.—Final Report [linois Board
World’s Fair Com., 77-92, 1 pl. Springfield, 1895.

—Low, A. P. Report on Explorations in Labrador.— Geol. Surv. Canada,
Ann. Rept., VIII, Pt. L, 387 pp. Ottawa, 1897.

—Macmillan & Co. A Treatise on Rocks, Rock-weathering, and Soils, by
George P. Merrill,—411 pp., 25 pl. New York, 1897. Elementary
Geology, by Ralph S. Tarr.—499 pp., 25 pl. New York, 1897.

Minnesota Academy of Natural Sciences. Bulletin, Vol. IV, No. 1, Part
I, 6 pls. Minneapolis, 1896.

—-Missouri Geological Survey. Biennial Report of State Geologist, 63 pp.,
7 pl. Surface Features of Missouri and Bibliography, Vol. X, 533 pp..
22 pl. Clay Deposits, by H. A. Wheeler, Vol. XI, 622 pp., 39 pl.
Jefferson City, 1897.

—MuntHe, Henr., Till Fragan om Foraminiferfaunan i Sydbaltiska
Kvartarlager. Aftryck ur Geol. Féren.i Stockholm Férhandl. Bd.
Toe) deed. S1OQG:

—North Carolina and Its Resources— State Board of Agriculture, 413 pp.
Raleigh, 1896.

Quarterly Journal Geological Society, Vol. LIII, Part II, No. 210, Io pls.
London, 1897. General Index No. 200 b, Part II La-Z.

—Revisita de Obras Publicas e Minas, tomo XXVIII, Nos. 325-326, 80

pp. Lisbon, 1897.
Revue de Géographie. Paris, May 1897.
Revisita de Obras Publicas e Minas. Nos. 327 E 328. Lisbon, 1897.

—Ruirs HEINRICH, The Clays and Clay-Working Industry of Colorado.
The Fullers Earth of South Dakota. (Published by permission of
Director U. S. Geol. Survey).

—-SARDESON, F. W. On the apical end of Endoceras, by Gerhard Holm.
—(Review.) Am. Geol. XIX, 60,61, 1897. Nomenclature of the
Galena and Maquoketa Series.—Am. Geol., XIX, 330-336, 1897. The
The Galena and Maquoketa Series—Am. Geol., XVIII, 356-368 ;
XIX, 21-35, gI-I11, 180-190, 2 pl. Minneapolis, 1896-7.

—SCHAFARJIK, DR. FRANZ., Die Pyroxen-Andesite des Cserhat. Eine
petrographische und geologische Studie. Mittheilungen aus dem
Jahrbuche der Kgl. Ungarischen Geologischen Anstalt. IX. Band.
7. Budapest, 1895.

Schriften der Physikalisch-Okonomischen Gesellschaft zu Kénigsberg
in Pr., 1895; Do., 1896. Kdénigsberg.

—SJOGREN, Hj., Bulletin of the Geological Institution of the University of
Upsala. Edited by Hj. Sjégren. Vol. II, Part 2, No. 4, Upsala, 1896.

538 RECENT PUBLICATIONS

—SMITH, JAMES PERRIN. Marine Fossils from the Coal Measures of
Arkansas.— Reprint, Proc. Am. Philos. Soc., XXXV, 72 pp.,g pil.
Philadelphia, 1897.

—STANTON, TimotHy W. Faunal Relations of the Eocene and Upper
Cretaceous on the Pacific Coast.— Seventeenth Ann. Rept. U. S. Geol.
Surv., pp. 1005-1048, pl. 63-67. Washington, 1896.

—STEVENSON, J. J. A Summary Description of the Geology of Pennsyl-
vania.— (Review.) Science, N. S., III, No. 76, 2-3, 1896. Notes
on the Geology of the Bbermudas.— Trans. N. Y. Acad. Sci., XVI, 96—
UZAG ES IPle Ooze

—SVEDELIUS, GusTAF E., Om Jarnets kirtiska Langd- och Temperatur-
f6randringar, Upsala, 1896.

U. S. GEOLOGICAL SURVEY.

Bulletin of the Geological Survey, No. 148. Analyses of Dock and
Analytical Methods U. S. Geol. Survey, 1880-1896. Clarke and
Hildebrand.

Geologic Section Along the New and Kanawha rivers in West Virginia,

by Marius R. Campbell and Walter C. Mendenhall, 17th Ann., Part II,
Economic Geology and Hydrography, 1895-6.

Glacial Brick Clays of Rhode Island and Southeastren Massachusetts,
by N.S. Shaler, J. B. Woodworth and C. F. Marbut, 17th Ann.
Rept., Part I, Director's Report and other papers. Washington,
1897.

—SWERINZEW, L. Zur Entstehung der Alpenseen.— Pam. 36 pp. St.
Petersburg, 1896.

—TARR, RALPH S. Evidences of Glaciation in Labradorand Baffin Land.
—Am. Geol., XIX, 191-197, 1 pl., 1897. Former extension of Cor-
nell glacier near the southern end of Melville Bay.— Bull. Geol. Soc.
Am., VIII, 251-268, 4 pl., 1897. Rapidity of Weathering and Stream
erosion in the Arctic latitudes—Am. Geol. XIX, 131-136, 1 pl.
Minneapolis, 1897. The Arctic Sea as a geological agent.— Am. |
Jour. Sci., (4), Vol. III, 223-229. New Haven, 1897.

—TAYLOR, FRANK B. Correlation of Erie-Huron beaches with outlets
and moraines in southeastern Michigan.— Bull. Geol. Soc. Am.,
VIII, 31-58, 2 pl. Rochester, 1897. Scoured bowlders of the Mat-
tawa valley.—Am. Jour. Sci., (4), Vol. III, 208-218. New Haven,
1897.

—TuRNER, HENRY W. Further contributions to the geology of the Sierra

Nevada.— Seventeenth Ann. Rept. U. S. Geol. Surv., pp. 521-740, pl.
17-47. Washington, 1897.

RECENT PUBLICATIONS 539

—TYRRELL, J. BURR. Report on the country between Athabasca Lake
and Churchill River.— Geol. Surv. of Canada, Ann. Rept., VIII, Pt.
D, pp. 120, map. Ottawa, 1896.

—UssinG, N. V. and Victor MADSEN, Beskrivelse til Geologisk Kort
over Danmark (i Maalestok 1: 100,000). Kortbladet Hindsholm. Geol.

Survey Denmark. Copenhagen, 1897.

—VAN OrNuM, J. L. Topographical Surveys, their methods and value.—
Bull. Univ. Wisconsin, Eng. Ser.,"I, 331-369, 1896.

—WAHNSCHAFFE, FELIX. Ueber Aufschliisse im Diluvium bei Halbe.
Jahr. d. K. K. Preuss. Geol. Landesanstalt, 1896, 126-135, 1897.

—WaAkD, LESTER F. Descriptions of the species of Cycadeoidea or
fossil Cycadean trunks thus far found in the Iron Ore Belt, Potomac
formation of Maryland.—Proc. Biol. Soc. Washington, XI, 1-17,
1897.

—Watson, THoMAS L. Bibliography of the geological, mineralogical,

Bull. Am.

and paleontological literature of the state of Virginia.
Pal:, 1 No: 7, pp. 109. . Ithaca, 1897.

—WHITE, DAvip. Age of the Lower Coal of Henry County, Missouri. -—
Bull. Am. Geol. Soc., VIII, 289-304, 1897.

—WHITEAVES, J. F. Palzozoic Fossils, III, iii; No. 4. The fossils of
the Galena, Trenton, and Black River formations of Lake Winnepeg
and its vicinity.—Geol. Surv. Canada, 129-242, pl. 7. Ottawa, 1897.

—-WHITFIELD, R. P., Descriptions of New Species of Silurian Fossils from
Near Fort Cassin and Elsewhere on Lake Champlain. Pls. IV and
V. Bulletin American Museum Natural History, Vol. IX, Article XI,

pp. 177-184.
—Descriptions of Species of Rudiste from Cretaceous Rocks of Jamaica,
W. I. Collected and Presented by Mr. F.C. Nichols. Bulletin
American Museum Natural History, Vol. 1X, Article XII,pp. 185—196.

—WHITNEY, MILTON, Frank D. Gardner and Lyman J. Briggs. An
Electrical Method of Determining the Moisture Content of Arable
Soils. Bulletin No. 6, U. S. Dept. of Agriculture, Washington, 1897.

WHITNEY, MILTON, and THomAS MEANS, An Electrical Method of
Determining the Soluble Salt Contents of Soils with some Results on
the Effect of Water and Soluble Salts on the Electrical Resistance
of Soils. Bulletin No. 8, U. S. Dept. of Agriculture, Washington,
1897.

—WHITNEY, MILTON, and LYMAN J. BriaGs, An Electrical Method of
Determining the Temperature of Soils. Bulletin No. 7, U. S. Dept.
of Agriculture, Washington, 1897.

540 RECENT PUBLICATIONS

—WILLIAMS, HENRY S. On the southern Devonian Formations.— Am.
Jour. Sci, (4), Vol. III, 393-403, 1897.

—WooLMAN, LEwIs, Report on Artesian Wells in Southern New Jersey.
From the Annual Report of the State Geologist of New Jersey for the
year 1896. Keport on Artesian Wells mostly in Northern New Jersey.
fbid. Stratigraphy of the Fish House Black Clay and Associated
Gravels. /dzd.

-—WyYSOGORSKI, JOHANN and W. DAMES. Ueber das Alter der Sadewitzer
Diluvial-Geschiebe.— Zeit. d. Deutsch. geol. Gesellschaft, 407-413,
1806.

THE

POON NL OOF GEOLOGY

SEPTEMBER-OCTOBER, 1897

THE NEWARK SYSTEM OF NEW JERSEY:

Tue Newark system extends across the northern part of New
Jersey, forming a belt which is about thirty-two miles wide along
the Delaware River, while its width at the New York state line is
about fifteen miles. The southeastern boundary from Trenton
northeastward to Staten Island is for the most part formed by
the overlying Cretaceous beds. Near Trenton, however, the
underlying Philadelphia gneiss outcrops for a few miles. The
waters of the Kill von Kull, New York Bay and Hudson
River form the boundary from Staten Island northward. The
northwestern boundary is irregular and is formed entirely by
older rocks, —crystallines and Paleozoic shales and limestones.
This paper has to do with that part of the area lying southwest
of a line drawn from Metuchen, through Plainfield to Peapack.

Topography.—In general the area is a gently rolling plain,
having an average elevation of 100 to 250 feet A.T. The plain
is interrupted by the valleys and trenches of the present streams
and hills, ridges and plateaus of harder rock. The largest of
these is the Hunterdon plateau. Commencing at Raven Rock on
the Delaware River a prominent escarpment extends northeast-
ward, past Flemington, where it bends north and then northwest,
finally terminating near Lansdown about eighteen miles from the

* Published by permission of the State Geologist of New Jersey. For a more
detailed statement of all the facts upon which this paper is based, see Annual Report

of the State Geologist for 1896, pp. 25-88.
VOL: V., No.6: 541

542 HENRY B. KUMMEL

Delaware River. Northwest of this line is a broad plateau, hav-
ing an average elevation of about 600 feet. It extends west-
ward into Pennsylvania, being dissected by the Delaware to a
depth of 4oo to 500 feet. Its highest part is along the south
and east, about a mile back from the top of the escarpment.
Thence it declines in elevation very gently northward and west-
ward. The escarpment is most marked in the vicinity of Flem-
ington, where the contrast in hardness between the rocks of the
plateau and of the low ground is the most marked.

Sourland plateau extends from Lambertville on the Delaware,
northeastward for seventeen miles. It has an average width of
four and a half miles and varies in height from 450 to 560 feet.
The backbone of the plateau is a belt of trap rock, a mile in
width, but the hard sandstones and argillites on either side rise
nearly to the same elevation. In the vicinity of Hopewell and
northward, the plateau is separated from the low plain to the
southeast by an escarpment varying from 200 to 400 feet in
height. Other masses of trap rock forming minor hills and
ridges rise from 200 to 500 or 600 feet above the general level.
Along the northwestern boundary also there are several marked
elevations due to massive quartzite conglomerates.

THE ROCKS.

It has been found possible to divide the sedimentary rocks
of the Newark system into three subdivisions.* These are not
based upon paleontological evidence, since fossils are too few to
be used for this purpose, but on lithological differences, which
permit the establishment of recognizable horizons. While fully
aware of the dangers attending the use of lithological characters
in correlation, the author is confident that in this case they have
been reduced to a minimum, owing to the care with which the
beds have been traced step by step. The beds of the three series

* Practically all the outcrops and sections—many hundreds in number — have
been examined and plotted. All the roads and nearly all the stream beds have been

traversed. So monotonous are the beds that it is only by this detailed work that there
is any possibility of detecting and tracing the structural complications.

THE NEWARK SYSTEM OF NEW JERSEY 543

grade into each other vertically through transition zones several
hundred feet in thickness, so that it is not always easy to delimit
them exactly in the field. Moreover, all three members lose to
a great extent their distinctive characteristics when traced along
the strike of the northwestern boundary north of Pittstown. With
these exceptions, however, the beds of each division are en masse
quite unlike and readily separable from each other. The accom-
panying map shows their location and the main faults by which
they are repeated.

Stockton series—TYhe basal beds of the system are found at
Trenton where they rest unconformably upon the older crystal-
line rocks. They consist of (a) coarse, more or less disinte-
grated arkose conglomerates; (4) yellow, micaceous, feldspathic
sandstone; (c) brown-red sandstones or freestones, and (ad)
soft red argillaceous shales. These are interbedded and many
times repeated, a fact which indicates rapidly changing and
recurrent conditions of sedimentation. Although there are many
layers of red shale in this subdivision the characteristic beds are
the arkose conglomerates and sandstones, the latter of which
afford valuable building stones.

In addition to the cross-bedded structure which often prevails
in the sandstones, ripple-marks, mud-cracks and impressions of
rain drops occur. The rapid alternation from conglomerates to
shales and wice versa, the changes in composition in individual
beds, the cross-bedding, ripple-marks, etc., all indicate very
clearly that these beds were deposited in shallow water in close
proximity to the shore. The bulk of the material of which they
are composed was derived from the crystalline rocks on the south
and southwest.

Owing to the tilting and faulting, the Stockton beds out-
crop in several belts as shown by the map. The most important
areas are (a) the Trenton area, which extends northeastward to
Princeton beyond which place it is mostly buried by Cretaceous
and Jamesburg deposits ; (4) the Hopewell area along the south-
eastern face of the Sourland plateau, where the upper part of the
series has been brought to the surface by a fault; (c) the

544 HENRY B. KUMMEL

Stockton area, where the upper layers are exposed in numerous
quarries near the village of Stockton; (2) the area north of
Flemington.

In the Stockton area the upper limit of the series extends
along the crest of the escarpment of the Hunterdon plateau, the
steep slope being formed by the upper beds of Stockton series
which are here predominantly red shales, with an occasional
sandy layer. Northeastward this belt is terminated by a great
fault which crosses the beds obliquely so that the belt becomes
narrower and finally pinches out a few miles southwest of Flem-
ington. Within this area the more massive conglomeratic beds
form three broad low ridges, each of which terminates somewhat
abruptly at the fault.

An important modification was found in the character of this
series within the area north of Flemington. Where the rocks
first occur near Flemington, they consist of coarse arkose sand-
stones and red shales. The transition here to the overlying series
is through sandy shales similar in texture and thickness to the
uppermost layers northwest of Stockton. As the northwestern
border of the formation is approached the arkose conglomerate
and sandstones give place to red shale beds or sandstones and
conglomerates of a different type. For a distance of four miles
southeast of Clinton the basal beds of the formation rest uncon-
formably upon Silurian shales, limestones, and still older quartz-
ite and gneiss. Material from these formations has determined
the local character of the Newark beds. In place of the free-
splitting brown and red sandstones, there occur coarser beds
made up largely of thin bits of shale, and small quartzite pebbles.
Although the Stockton beds rest in part upon the limestone and
gneiss, these rocks occur but rarely in this part of the newer
formation. Their comparative absence has not been satisfactorily
explained.

Lockatong series—Above the Stockton beds there is a series
of hard, dark-colored shales and flagstones, which I have called
the Lockatong beds from the name of the creek in Hunterdon
county, along which they are best exposed. They consist of

THE NEWARK SYSTEM OF NEW JERSEY 545

(a) carbonaceous shales, which split readily along the bedding
planes into thin laminz, but have no true slaty cleavage ; (0)
hard, massive, black and bluish-purple argillites; (c) dark gray
and green flagstones; (a) dark red shales approaching a flag-
stone; (¢) and occasional thin layers of highly calcareous shales.
There are all gradations between these somewhat distinct
types, so that the varieties of individual beds are almost
countless. Some of the argillites are specked with minute crys-
tals of calcite-and the faces of jdint planes and cavities are fre-
quently covered with deposits of the same mineral. Minute
crystals of iron pyrites occur frequently in some layers, but
apart from them and the calcite, secondary minerals were not
found, macroscopically, in these beds.

Both ripple-marks and mud-cracks occur at all horizons in
the Lockatong beds, showing that shallow water conditions pre-
vailed throughout the time of their deposition. On the other
hand, the absence of strong currents or violent shore action is
indicated by the extreme fineness of the material.

Owing to the faulting these beds occur in several well-marked
belts, in each case overlying conformably the Stockton series.
The first belt reaches the Delaware between Wilburtha and
Washington’s Crossing, and extends northeastward through
Ewingville, Lawrenceville, and Princeton, where there are several
large quarries in the argillite beds. East of the Millstone River
the limits of this belt cannot be determined accurately owing to
the veneer of the Jamesburg formation, but from a few scattered
outcrops and borings, these beds probably cross the Raritan
River below the mouth of Lawrence Brook.

The Lockatong beds occur again along the southeastern side
of the Sourland plateau, resting upon the narrow belt of Stock-
ton sandstones which forms the escarpment of this upland. From
the Delaware River to the village of Newmarket the upper lmit
of the beds lies a little below the trap sheet which forms the
backbone of the upland. The interval between them is occu-
pied by the softer red shales of the third series, which are some-
what metamorphosed near the igneous rock. Northeast of New-

546 HENRY B. KUMMEL

market, owing to a sharp curve in the trap sheet by which it
crosses the beds nearly at right angles, the Lockatong beds occur
on both sides of the trap, their upper limit being about 1760

s
Ty
ys.
(c}
v :
\o)

A

Plainfield

Frenchtown\\#

il Crystallines

Paleogoic
F223] Stockton
Lockatong
(a) Brunswick
peste Trap

= Cretaceous Lambertville

Faults

a si . [ z
---- Trap Dikes P = ,
SUBDIVISIONS OF THE NEWARK-SYSTEM : CS

AND
PRINCIPAL TRAP AREAS

BY HENRY B. KUMMEL
Scale of Miles 5

Sytstown
=

SIN gers ome eas dO)

J AR Prince Del.

feet above the latter. The plateau, which owes its elevation to
the hardness and durability of the argillite flagstones and trap,
is terminated on the northeast by the fault.

The most extended outcrop of the Lockatong beds occurs on
the Hunterdon plateau, in the region known as “the Swamp.”
As shown on the accompanying map the width of the outcrop is
greater here than elsewhere due to diminished dips, 10° to 13°
here as against 15° to 20° on the Sourland plateau, and the belt

THE NEWARK SYSTEM OF NEW JERSEY 547

forms a broad regular curve, due to the synclinal structure. The
height of the Hunterdon plateau is due to the wide outcrop,
curving strike and hardness of these rocks and of the upper layers
of the Stockton series, all of which have retarded greatly the
forces of denudation, so that whereas the adjoining softer rocks
have been reduced to an average elevation of under 200 feet, this
belt has an elevation of from 500 to 700 feet.

Along the Lockatong and Wickecheoke creeks, which have
deeply incised the margin of the plateau, rapids and falls abound.
Hard dark red flags are interbedded with the black argillites,
and some of the more pronounced beds can be easily traced for.
several miles along the curving strike. This was done in so
many cases at different horizons as to render it almost certain
that this belt is not traversed by faults of any magnitude. The
width of outcrop is due to the great thickness and the gentle
dip.

Modification of the Lockatong beds.—Important modifications
were found to occur in this series near the northwestern bound-
ary. The shales and argillites grade into sandstones, and these
into coarse conglomerates. Some layers become slightly arkose.
This change occurs along the strike, and is accomplished within
six miles or less. Within a mile and one-half along the strike
from the point where the first pebble-bearing layers were noted,
the series is composed chiefly of massive conglomerates in which
the pebbles are frequently six or eight inches in diameter. Since
not only the Lockatong beds but the next higher series also
grade into these marginal conglomerates, it will be well to post-
pone further consideration of them for a brief space.

The Lockatong beds give rise toa rather heavy wet clay
soil. The surface is quite thickly strewn with slabs of argillite
and flagstone, and on the slopes outcrops are generally abun-
dant. Except in places favorable to the accumulation of the
soil from higher slopes its depth is generally less than five or six
feet.

The Brunswick shale series —I\ have applied this name to the
great thickness of soft shales and occasional sandstone layers

548 HENRY B. KUMMEL

which overlie the Lockatong beds, and which are so well exposed
in the valley of Raritan, particularly near New Brunswick. They
are predominantly red in color, although a few purple, green,
yellow, and black layers occur. In general this series consists
of a monotonous succession of very soft argillaceous red shales
which crumble readily to minute fragments, or split into thin
flakes. Much of it is porous, the minute, irregular-shaped cavi-
ties being often partially filled with a calcareous powder. Cal-
cite veins and crystals are common in some layers. Locally
lenticular masses of green shale occur in the red. In size these
ange up to a foot or two in diameter, and vary in shape from
nearly spherical to lenticular masses, narrowing down to thin
sheets along cracks. They are undoubtedly due to chemical
changes resulting in the leaching of the shale.

Although the majority of this series are soft red shales, there
are some hard layers, chiefly near the base, and occasional beds
of fine-grained sandstone and flagstones, some of which afford
valuable building material. Massive conglomerates along the
northwestern border are in part the shoreward correlatives of the
red shales.

Evidence that the shales were deposited in shallow water is
abundant. Ripple-marks, mud-cracks and rain-drop impressions
occur at many horizons. In some quarries imprints of leaves, of
tree stems, or the stems themselves are frequently found. The
numerous reptile tracks which have made the Newark beds
famous occur chiefly in this subdivision. Typical exposures
occur along the Raritan River, particularly near New Brunswick.

The Brunswick beds underlie all the region under discussion
except that occupied by the Lockatong and Stockton beds and
the trap rocks. This area is considerably more than two-thirds
of the whole, partly because of the great thickness of the series
and partly because the beds have been bent into broad, gentle
folds. Standing on the northern end of Sourland plateau one has
a magnificent view of the low plain formed on the Brunswick
shales, chiefly in the Raritan valley, of the trap ridges which
interrupt its continuity and of the enclosing highlands. To the

THE NEWARK SYSTEM OF NEW JERSEY 549

west is the Hunterdon escarpment, forming the westward limit
of the Brunswick shales and marking the line of a great fault,
by which the rocks of the plateau have been uplifted several
thousand feet."

Thirteen to sixteen miles to the north across the low shale
plain are the gneiss highlands, and eight miles northeastward
are the curving level crests of the Watchung trap ridges which are
interbedded with the Brunswick shales, and beyond which the
shale lowland extends. No high ground meets the eye to the
east toward New Brunswick thirteen miles away, but to the south
rises the Rocky Hill trap ridge, at one point deeply cut through
by the Millstone, and there marking the approximate limit of
the Brunswick shales. To the southwest there stretches away
on either side of the narrow plateau on which we stand, a
strip of rolling lowland, likewise underlain by the Brunswick
shales.

These rocks also outcrop above the Lockatong series in the
northern part of the Hunterdon plateau. They are exposed in
high bluffs along the Delaware above and below Frenchtown.
It was found that the shales of this area when traced along their
strike towards the margin of the formation became rapidly coarser,
passing along some horizons into massive conglomerates. , It
will be remembered that similar changes were found to take place
in the Lockatong and Stockton beds, so that within two or three
miles of the margin the distinctions between the three subdi-
visions are largely obliterated.

Quartzsite conglomerates At a number of points along the
northwestern boundary of the Newark system there are thick
accumulations of massive conglomerates, composed chiefly of
quartzite and hard sandstone. Pebbles of limestone, gneiss and
shale occur in some layers, but sparingly. All the constituent

*The height of the plateau above the red shale plain is not due to the fault,
although the latter lies along the foot of the escarpment. As shown by Professor
Davis (Proc. Bost. Soc. of Nat. Hist., Vol. XXIV, pp. 365-423) this region was base-
leveled in Cretaceous times or thereabouts, and the present topography is due to dif-

ferential degradation of rock masses of unequal hardness, consequent upon an uplift
which affected the whole region.

550 HENRY B. KUMMEL

materials are well rounded, a fact which in the case of the hard
quartzites indicates a long period of attrition.

These conglomerates interbedded with sandstones and shales
are best exposed in the ‘pebble bluffs” along the Delaware,
above Milford. The conglomerates form lenticular beds which
occasionally thin out in the distance of a few rods, to be replaced
by beds of different texture. The alternation of the beds beto-
kens shore conditions.

The heaviest accumulations of the quartzite conglomerate
underlie the high region stretching northwest from Pittstown
and south of Pattenburg. This region is known as ‘‘the Bar-
rens”’ from the nature of the soil, an exceedingly gravelly clay
resulting from the disintegration of the conglomerate. Less
massive accumulations occur, also, at other points, chiefly south
of Clinton, and again four miles north of Peapack, where there
is an outlier of this rock called Mount Paul.

Calcareous conglomerates.— Conglomerates composed almost
entirely of limestone fragments, occur at a number of localities
along this border. This rock is in appearance almost the exact
counterpart of the famous ‘‘ Potomac marble” quarried at Point
of Rocks, Maryland. The limestone pebbles are usually bluish
or gray, sometimes reddish, set in a red mud matrix, so that the
rock has a variegated appearance. The average diameter of the
larger constituents is six or eight inches, but bowlders three feet
in diameter have been seen. The larger fragments are generally
rounded, but the majority of the smaller are sharp cornered, or
at most subangular. Compared with the pebbles in the quartzite
conglomerate, the limestone pebbles are poorly rounded, a fact of
some significance in connection with the origin and source of the
materials, since with equal transportation, the softer limestones
must have been most worn. In many localities this conglomer-
ate is so pure a limestone that it is quarried and burnt for lime
for local use.

The relations of these conglomerates to the older rocks along
the border are significant. In some localities the calcareous
conglomerates adjoin small areas of Paleozoic limestone from

THE NEWARK SYSTEM OF NEW JERSEY 551

which the materials may have been and probably were derived.
In other cases, and this is true of the largest areas, the calcare-
ous conglomerates abut against the gneissic rocks, and for much
of this distance it is certain that no limestone occurs between the
gneiss and conglomerate, at least not at the surface horizon.
Gneissic pebbles, however, occur but rarely in the conglomerate.
Substantially the same conditions prevail in the case of the
quartzite conglomerate. For the most part it adjoins the gneiss,
but gneissic pebbles in it are very rare. The known areas of
quartzite from which the materials could have been derived are
small, and in general not near the massive conglomerate beds.
These facts can be explained on the hypothesis of a fault or
series of faults along the northwestern border. But on the Del-
aware River, at Monroe, Pa., the only locality along the border
where even an approach to a good section was found, the con-
glomerates seem rather to overlap the older rocks at a low
angle, than to be faulted against them. In view of the contra-
dictory nature of the evidence, the question of faults along this
border is still an open one.

The relation of the conglomerates to the shales is also an
interesting and significant one. When traced along the strike
the shales and argillites are found to grade into coarser beds which
at some horizons become the massive conglomerates near the
border. That this is the case has been established beyond a
shadow of a doubt by numerous observations. Time and again
thin pebbly layers were seen to appear in the shales and to
increase in thickness and numbers until they became massive
conglomerates. This is true both of the calcareous and of the
quartzite conglomerates.

These conglomerates do not, therefore, form a separate
horizon but range through the whole formation. Those in the
bluffs on the Delaware River above Milford belong with the Bruns-
wick shales. So also do a part of those of the Barrens south-
west of Pattenburg. Those of the Barrens north and northwest
of Pittstown pass into the Lockatong beds and are therefore
older than the conglomerates nearer the Delaware. The pebbly

Ri HENRY B. KUMMEL

beds south of Clinton belong in the Stockton series. Both the
calcareous and quartzite conglomerates near Pottersville and
Peapack belong with the Brunswick beds.

It must be understood that what has been said concerning
the above conglomerates does not apply to the conglomerate
layers interbedded with shales and sandstones, which occur
either along the southeastern part of the formation, near Hope-
well or near Stockton. The latter are comparatively thin beds
of little importance from a topographical standpoint, and belong
to the Stockton series. They present no features of particular
interest.

Thickness of the Newark sedimentary beds.— All estimates of
the thickness of these sedimentary rocks contain an element of
uncertainty. This arises from the monotonous character of the
beds and the difficulty of detecting and measuring the faults.
In addition to several very large dislocations which have been
located accurately, a number of smaller fractures have been
observed in quarries, railroad cuts, stream bluffs, and other
exposures. Most of these could not be traced beyond the point
of exposure. After making all possible allowance for known
faults, 1 am compelled to admit that the facts in hand indicate a
vastly greater thickness than has usually been supposed.

The thickness of the Stockton beds between Trenton and
Wilburtha seems to be 2300 feet. No estimates can be made in
the area near Hopewell, since only the upper part of the series,
650 feet or so, is there exposed. At Brookville below Stockton
the base of the formation is brought to the surface by a fault and
the thickness seems to be 4700 feet. No positive evidence of a
fault could be found within this area to account for the greater
thickness as compared with the belt near Trenton, whereas there
is slight evidence that the whole series is not found near the
latter place.

The thickness of the Lockatong beds is best shown on Hun-
terdon plateau. Here the upper and lower limits can be care-
fully located. The dip is more than ordinarily uniform and
outcrops are sufficiently numerous to prevent any great error in

THE NEWARK SYSTEM OF NEW JERSEY 553

the calculation. More than this, the sweeping curve of these
rocks, the uniform width of the belt, and the possibility of
tracing certain subordinate but well-marked layers continuously
along the strike, precludes the idea that any great part of its
apparent thickness is due to repetition by faulting. Three
independent measurements, made at intervals several miles
apart gave results of 3540 feet, 3450 feet, and 3500 feet
respectively.

Three measurements of the thickness of these same beds in
the Sourland plateau gave substantially the same results, z. é.,
3600 feet, 3650 feet, and 3660 feet. The fact that for a part of
the distance a great trap sheet has been intruded into these
beds and elsewhere has caused changes in the adjoining red
shales, makes it a little more difficult to measure these beds.
The fact that the thickness of these beds in Sourland plateau
agrees so closely with that of the same beds on Hunterdon
plateau is further reason for believing that the figures here given
represent very closely the actual thickness. To suppose other-
wise is to assume that these two separate areas are each trav-
ersed by faults, whose throw, by a remarkable coincidence, is
almost exactly the same, but no traces of which have been dis-
covered by areal work of the most detailed character.

The thickness of the Lockatong beds of the belt near Ewing-
ville and Princeton seems to be only about half of that in the
other two regions, z.¢., 1700 to 1800 feet. As noted above, the
same relative thinness was observed in the Stockton beds near
Trenton as compared with those further north. The explana-
tion may lie in the fact that the beds of the thinner belts are
nearer the old shore line than the others. Stratified deposits
have the form of an unsymmetrical lens which thins out very
rapidly shoreward and very gradually seaward. It is to be
expected, therefore, that the thickness of this belt would be
somewhat less than that of the others, but it may be fairly ques-
tioned whether in the case of such fine deposits the difference
would be so great as that indicated by the figures.

The thickness of the Brunswick beds is even more difficult

554 HENRY B. KUMMEL

to estimate accurately. This is due to the uniformity of the red
shale, which renders it very difficult to detect the presence of
faults, to the folded structure, and to the fact that the entire
thickness is not present in this part of the state.

West of Ringoes the shales form a syncline whose axis
plunges northwest. Estimates made here show that between
7000 and 8000 feet of shales are involved in this folding.
Between the mouth of Lawrence Brook, east of New Brunswick,
where the shales disappear beneath the Cretaceous cover, and
the base of First mountain, back of Bound Brook, the beds are
10,000 feet thick, provided there are no faults in the interven-
ing region. Inthe Raritan River bluffs below New Brunswick
three fault breccias were found, but nothing is known as to
the amount of dislocation beyond the fact that it was not suffi-
cient to expose the Lockatong beds which are here at a horizon
about 1000 feet lower. From the amount of disturbance and
crushing which is known to accompany great faults in other
parts of this area, the presumption is that these are Staal lan
deduction of 1000 feet from the above estimate would seem to
be ample for these and any undiscovered fractures. Nine thou-
sand feet, however, is not enough, since neither the base nor the
top of the Brunswick beds is included in this section. They
certainly extend for 2000 to 3000 feet above the base of First
Mountain. In the light of the present facts an estimated thick-
ness of 12000 feet for the Brunswick shales does not appear
excessive, although in view of the uncertainties connected with
the structure, too much emphasis must not be placed upon it.

The total thickness, therefore, of the sedimentary rocks of
the Newark system in western New Jersey seems to be about
20,000 feet. These figures are so great that one naturally hesi-
tates to accept them, but the facts, so far as known, do not per-
mit any other interpretation. I began my work feeling confident
that the thickness of the beds was much less than this, and that
they were many times repeated by faults. However, many of
the faults found cross the beds at such angles as to be ineffec-
tive in repeating the strata. Furthermore, the fact that the

THE NEWARK SYSTEM OF NEW JERSEY 555

three estimates of the thickness of the Lockatong beds in the
Hunterdon plateau, where the outcrop is so curved, agree closely
one with another, and also with the various estimates of the
same beds on Sourland plateau, make it improbable that the
great thickness of this series is due to faults. So, too, the thick-
ness of a part of the Brunswick shales involved in a synclinal
fold can be accurately determined and the possibility of the
faulting there eliminated. Again a narrow trap dike was traced
uninterruptedly from the back of Sourland Mountain near Rock-
town to Copper Hill, a distance of five miles. The dike crosses
the strike at an angle of 45° and the thickness of the shales
thus traversed is between 6000 and 7000 feet. There are
reasons which cannot here be specified for concluding that the
Sourland trap sheet, and therefore the dike, were intruded into
the shales during Newark time, and before or contemporaneous
with the tilting. If these reasons are valid the continuity of the
dike is proof that the shales traversed by it are not cut by
faults along the strike. Since such great thicknesses prevail
in these beds, which are only a part of the whole system, there
is the more reason for accepting the figures given above. It
can certainly be claimed for these estimates that they rest upon
a much larger basis of fact than any previous figures.

Trap rock.—The trap rocks in the Newark series have been
described by various writers’ who have shown that both intrusive
and extrusive sheets occur. In this connection I desire briefly
to call attention to a few new facts which confirm the conclusions
of some of the earlier observers.

Three narrow dikes were found to start from the upper sur-
face of the Sourland Mountain trap mass, and were traced
through the overlying shales for several miles. Their existence
proves conclusively that this sheet is intrusive. It would naturally
follow that the continuation of Sourland Mountain in Penn-
sylvania is also intrusive, although Lyman? has published very
positive views to the contrary. Moreover the fact that the trap

*Chiefly Cook, RUSSELL, DAvis, DARTON, IDDINGs.
2 Pennsylvania State Geol. Surv., Final Rept., Vol. III, Pt. II, p. 262.

556 HENRY B. KUMMEL

locally cuts across shales for a total of 1800 feet is certainly well ©
established. The Rocky Hill trap sheet does not follow the
strike of the shales but crosses them more or less obliquely.
Where it terminates near Hopewell it is 6000 feet’ or more
above the base of the Brunswick shales, whereas at Deans sta-
tion where it disappears beneath the Cretaceous beds, it is 1500
feet below them. If we are correct in assuming that Rocky
Hill is a continuation of the Palisades, the sheet descends still
further, since along the Hudson it is found in beds which cer-
tainly belong to the Stockton series. A recently dug quarry
opposite Point Pleasant, Pa., on the Delaware, shows that the
trap mass there crosses the shales at a steep angle and is also
intrusive.

Near Sand Brook village, southwest of Flemington, there is
a low horseshoe-shaped ridge of trap formed by the outcropping
edges of a synclinal sheet whose axis plunges northwestward.
This sheet is extrusive in origin, as is shown by the following
facts: (a) It is conformable to the enclosing shale; (6) the
upper surface is everywhere extremely vesicular and only the
lower portion is dense and full grained; (c) the overlying shale
is absolutely unaltered within one and two feet of the trap; (@)
red shale has filled some of the cavities of, the vesicular trap,
and in one locality a thin layer of finely comminuted trap, glass
and red shale lies between the normal red shale and the vesicular
trap. This sheet has not heretofore been described or shown
upon published maps.

Metamorphosed shales—Numerous allusions are made in the
earlier reports to metamorphosed or ‘‘baked”’ shales associated
with the trap and in some cases found far away from any igneous
rocks. The black argillites of the Lockatong series have been
called ‘‘ baked shales”’ by some writers and their hardness and
blackness ascribed to the contact with the trap, although no
igneous rocks occur near them. Metamorphosed shales do occur
in connection with the larger in usive trap masses, but all the

* These figures are correct just so far as the above given figures of the total thick-
ness are reliable.

THE NEWARK SYSTEM OF NEW JERSEY 557

hard black shales are not ‘‘baked” shales. The most marked
macroscopic changes induced in the altered shales are (a) a
greater or less induration, (d) change in color,—the red shales
in general becoming purple and then a blue-black or green near
the trap, and (c) the development of secondary minerals, —
very commonly epidote and tourmaline. Where the change
has not produced definite crystal forms or nodules, an incip-
lent segregation has often occurred, giving the rock a more
or less mottled aspect, and on weathered surfaces a warty
appearance, although this latter characteristic is not limited to
the metamorphosed beds, but occurs in some layers of the Lock-
atong beds far from any known trap.

Of these three changes the third is believed to be the most
significant. Mere induration or change of color do not neces-
sarily signify ‘‘baking,” but when all three occur together and
only in layers in close proximity to certain trap sheets, proved
to be intrusive by their structural relations, the changes can be
safely ascribed to the igneous rock. Many of the baked shales,
on weathering, become a pale blue or ashy gray color, a tinge
never taken by other layers.

Metamorphosed shales occur both above and below the trap
of Sourland Mountain and are well exposed in the bluffs near
Lambertville. They are associated also with the Rocky Hill
sheet, fine exposures being found along the canal near Rocky
Hill village. In fact all the intrusive trap sheets are surrounded
by shales which have been more or less altered in texture, color,
and mineralogical constitution. Baked shales surely exist near
some of the trap sheets, but all hard, black shales of the system
are not baked, as was formerly supposed.

Unclassified beds —It has been impossible to classify definitely
the beds of a small area between Mount Airy, Lambertville, and
the mouth of Alexsocken Creek. Their structure is complex,
the dips vary greatly in direction and amount, and in many cases
they are crushed and distorted. Two small masses of trap
occur within the area, and some of the beds are certainly meta-
morphosed. Whether they belong to the Lockatong or Bruns-

558 HENRY B. KUMMEL

wick division I am unable to say on account of the complexity
of structure and their varied lithological character.

STRUCTURE.

Folds.—TYhe general structure is that of a faulted monocline,
the beds of which trend N- 30° 'E., and dip 12° or 157 to the
northwestward. Examined in more detail the structure is seen
to depart locally from the monocline. Several broad, gentle
flexures occur, in addition to a few sharply marked folds in the
vicinity of the intrusive traps and greater fault lines. A good
example of the former is seen in the shales of the Hunterdon
plateau, where the beds are so inclined that their outcropping
edges describe a great curve parallel on the east and southeast —
to the escarpment of the plateau. The structure is a shallow
syncline, whose axis is inclined to the northwest. Low folds
were found along the valley of the Raritan, particularly in the
region north of Somerville. From New Brunswick to Bound
Brook the dip is quite uniformly to the northwestward, averag-
ing 10°, but to the west the monocline is interrupted by gentle
flexures and swells which are difficult to trace because of the
absence of individuality in the layers. The broad outcrop of
the Brunswick shales in the Raritan valley is due in large part
to these low folds.

More definite folds—all synclines—occur (a) near the Sand
Brook trap sheet southwest of Flemington, (4) the New German-
town trap sheet, and (c) the Watchung traps whose great cres-
cent curves are due to the synclinal structure of the inclosing
shales.t In consequence of this fold the beds which outcrop
near the crystallines along Mine Brook, northeast of Bedminster
are at the same horizon as those between the two trap sheets
back of Plainfield and Bound Brook.

Several examples of sharp folds occur near Glen Moore south-
west of Hopewell and not far from the end of Rocky Hill ridge.
Other instances were noted near the faults.

The beds of the Stockton and Lockatong divisions are most

Cook, DARTON, DAVIs, et al.

THE NEWARK SYSTEM OF NEW JERSEY 559

constant in dip and strike, sa that the monoclinal structure is
most marked in these belts. The Brunswick shales are marked
by shallow folds, some covering an area of several square miles.
These combined with a fortunate arrangement of faults, have
greatly increased the area of red shale outcrop, and so permitted
the formation of the broad, rolling lowland, so characteristic of
the greater part of the Newark system.’

Faults —The location of the most important faults by which
these rocks are traversed is shown on the map. The Hopewell
fault, heretofore unrecognized, extends in a sinuous course from
near the Delaware River by Harbourtown, Hopewell, and thence
along the foot of the Sourland plateau escarpment, passing a
little west of Flagtown station on the Lehigh Valley Railroad.
It probably crosses into Pennsylvania, but its exact location at
the Delaware River could not be definitely determined.

The evidence of faulting along this line is as follows: (a)
the repetition of the strata; (0) crushed and contorted shales,
slickensided surfaces or overthrown dips at every exposure along
or near the fault line; (c) diversity of structure, dip and strike
—on opposite sides of the fault line; (d) contrasts in topog-
raphy and the termination of ridges at the fracture. The repe-
tition of the strata has already been alluded to in describing the
rocks. The map shows how the Stockton, Lockatong and
Brunswick beds are repeated, the beds to the northwest hav-
ing been uplifted. In the bed of every stream crossing the
fault, evidence of the fracture was found in the crushed and
slickensided condition of the rocks, but the fault plane was
nowhere exposed. Locally the rock has been so greatly sheared
as to destroy all traces of the bedding planes. Very marked
overthrown dips occur in a cut just west of Flagtown station,
which increase in steepness towards the fracture. Folds in the
Brunswick beds on the southeast side terminate abruptly against
the fault and do not affect the beds on the opposite side. The
high Sourland plateau composed of the hard trap and resistant

The details of structure, which must be omitted here, are given in the Annual
Report of the State Geologist of New Jersey for 1896, pp. 72-78.

560 HENRY B. KUMMEL

Lockatong argillite terminates abruptly where the fault crosses
the strike of its beds. The height and prominence of the escarp-
ment north of Skillman station is due to the contrast in hardness
of the Lockatong and Brunswick shales brought into juxtapo-
sition by the fracture.

The dislocation has been sufficient to bring to the surface
the upper part of the Stockton beds, and place them side by
side with the middle layers of the Brunswick shales. On the
basis of the above estimates of thickness the throw cannot be
less than 10,000 feet. The hade of the fault cannot be deter-
mined, since the fracture is nowhere exposed in section and its
location can rarely be determined within fifty yards. North of
Flagtown, where the Brunswick shales occur on both sides of the
fracture, its course could not be determined.

Flemington fault——The course of this fault previously noted
by other workers" is best seen by reference to the map. It is
located in the bluffs of the Delaware River by the juxtaposition
of the coarse arkose conglomerate (Stockton) with the black
argillite (Lockatong) a mile or more south of Stockton. The
line of dislocation is concealed by the talus of a small ravine.
From this point it extends in a northeasterly direction for three
miles, thence curving a little to the north so as to pass east of
Headquarters, southeast of Sand Brook and a mile west of the
center of Flemington. For much of this distance it extends
along the foot of the Hunterdon plateau escarpment.? For sev-
eral miles north of Flemington its exact location becomes doubt-
ful owing to the similarity of the adjoining beds, but one or
perhaps both of the two faults along the border west of Cushe-
tunk Mountain mark its northern extension. There is some rea-
son for believing that the trap of Round mountain, south of Cushe-
tunk Mountain, has ascended along the fracture, but this is not
conclusively proven.

The evidence of this fault is as complete as in the case of

*LEWIs, DARTON, NASON, LyMAN, and others.

?On a “conjectural” map of the Newark formation of New Jersey (Lyman, Pa.,
Geol. Surv. Summary Final Report, Vol. III, Pt. II, Plate 597, also Proc. Am.

THE NEWARK SYSTEM OF NEW JERSEY 561

the Hopewell fault. It consists of (a) repetition of the strata,
(6) diversity of structure and topography on the two sides, (c)
local disturbances, crushed beds, overthrown dips and slicken-
sides.

The uplift was on the northwest and was sufficient to bring
to the surface the base of the Stockton beds and just across the
river in Pennsylvania, the Paleozoic floor on which the New-
ark beds rest. East of Headquarters and Sergeantsville, lower
members of the Stockton series abut against beds of the
Brunswick series apparently 2600 feet above the base. If we
accept the thicknesses already given, the throw of the Flemington
fault near Headquarters is not less than 10,000 feet.

Half a mile east of Sand Brook village a small fault splits off
from the main fracture. By it a part of the Lockatong beds of
the plateau have been downthrown so that they occur to the
east, and apparently below the Stockton beds. The beds between
the two faults are much confused in structure.

Another and larger split fault was observed to branch from
the main fracture between Headquarters and Dilt’s Corners. It
crosses the Delaware about midway between Stockton and Lam-
bertville, and from a cursory examination I am inclined to
believe that it joins the Flemington fault again in Pennsylvania
about a mile from the river. The rocks of this block belong to
the Lockatong and Stockton series with some intrusive trap
masses. The general dip is south of west, although near the
faults there is much diversity. The beds on the east and south-
east have been downthrown relatively to the others. The com-
bined throw of this fault and the Flemington fault is about equal
to that of the latter further north.

Faults of a few feet throw have been noted in not a few cases
in quarries, railroad cuts and other exposures. In still other
cases the amount of dislocation could not be determined, but they
could not be traced beyond the point of exposure, and the throw

Philos. Soc., Vol. XX XIII, p. 194), the fault has been located several miles from its
proper position. A similar error is found on the map in Proc. Am. Philos. Soc.,
XXXI, No. 142.

562 HENRY B. KUMMEL

probably was not great. It is not believed that there are other
faults in the area examined whose throw is even one-tenth that of
the two great ones. I have alluded elsewhere to the possibility
of faults along the northwestern border. Two are shown upon the
map and others are believed to exist, but are not mapped. The
recurving horn of the Second Watchung Mountain is quite cer-
tainly separated from the crystallines bya fault. Further inves-
tigation of these points together with the study of the region not

yet examined, is now in progress.
Henry B. KUMMEL.
Lewis INSTITUTE, Chicago.

Tite GOrOGKAPEHY OF CALIFORNIA,

CONTENTS.
Introduction.

Method of making the relief map.
Topographic regions.

General topographic features.

The Sierra Nevada.

Cascade and Lava Sheet Mountains.

Klamath Mountains.

Coast Ranges.

The Great Valley of California.

Sierra Madre Mountains.

Owens River— Death Valley district.

Mohave — Colorado River district.
Minor topographic features.

Terraces.

Mesas.

Alluyial cones and fans.

Superimposed drainage.

Effects of vegetation on topography.

Sand dunes.

Hill slopes.

Topography as modified by rainfall.

INTRODUCTION.

THE writer has recently completed a relief map of California
on. a scale of I inch to,12 miles, and a vertical scale of I inch
to 12,000 feet. This makes it about 4 by 5 feet square, and the
highest peaks nearly 1% inches high.

The accompanying plate was taken from a photograph of
this map, and illustrates the main topographic features of the
state. To give some idea of the accuracy of the topography as
shown, the method of making the map is given.

Method of making the relief map.—As no topographic map of
the state was available, all the maps, levels, and other topographic
data were collected and a contour map of the state compiled.

563

564 IMOVAT al IDIVPILIOVNS IDA SD,

The topographic data were obtained principally from maps of
the State Mining Bureau,’ the United States Geological Survey,
the United States Coast and Geodetic Survey, various reconnais-
sance surveys, and from topographic descriptions and railway
surveys, and from elevations of peaks, passes, and places obtained
from various sources, both published and unpublished.

The gross relief of the state was then built up on a rigid
wooden base by cutting out card-boards of the proper thickness
in the shape of each 1000-foot contour and nailing them in place
one on’ top of the other. | Dle steps or terraces made) byathe
card-board and the minor details of relief were then filled in
with wax.? The best reference maps of the particular area being
modeled, were kept constantly at hand during the process of
filling in the details. After the completion of the original, a
negative was made in plaster of Paris, and from this the positives
are made. ihe completediirelich” map represents) ab outuesix
months of continuous and careful work. It shows the relief
with all the detail which the scale permits except in those parts
of the state in which topographic data are wanting. But even
in these parts the drainage made it possible to show the general
features fairly well.

TOPOGRAPHIC REGIONS.

General features—TVhe northern part of the state is largely
composed of three parallel and almost equally extensive topo-
graphic belts running lengthwise the state. These belts are the
Sierra Nevada on the east, the California Valley in the center,
and the Coast Ranges on the west. The Sierra Nevada, with its
main crest from 6000 to 13,000 feet above tide and its highest
peak reaching an elevation of nearly 15,000 feet, is the highest
and most prominent mountain system of the state. The con-
tinuation of the Sierra Nevada in extreme northern California is

*The Preliminary Mineralogical and Geological Map of California, issued in
1891 by the State Mining Bureau, was used as a base.

2This wax was composed of 16 parts of beeswax, 8 of cornstarch, 4 of Venice
turpentine, 1 of Venetian red, and 1 of sweet oil.

THE TOPOGRAPHY OF CALIFORNIA 565

called the Cascade and the Lava Sheet mountains. The moun-
tains next in importance to the Sierra Nevada are the Coast
Ranges, which have an average elevation of about 4000 feet, a

RELIEF MAP

CALIFORNIA

ny

GEOLOGICAL DEPARTMEN™
STANFORD UNIVERSITY, CALIFORNIA

width of 50 to 100 miles, and with the exception of a break at
San Francisco Bay, extend along the coast for the full length of
the state. The Coast Ranges, however, are more or less broken
at a number of places, thus giving rise to rather distinct groups
of mountains which have received special names. The southern

566 NOAH FIELDS DRAKE

end of the Sierra Nevada makes a sharp curve to the west, meet-
ing and uniting at Téjon Pass with an eastward curving branch
of the Coast Ranges.

The Klamath Mountains, occupying the northwestern part of
the state, unite the Coast Ranges and the Cascade Mountains.
Between these mountain ranges lies the California Valley, which
extends nearly northwest and southeast, and is about 400 miles
long by 50 miles wide. It is drained by the Sacramento and
San Joaquin rivers. .

The southern part of the state has three distinct topographic
areas, one of which lies along or near the coast, and is the con-
tinuation of the Coast Ranges under the name of the Sierra
Madre Mountains. This mountain system is composed of several
different ranges, the principal ones being the San Gabriel, the
San Bernardino, and the San Jacinto. The breaks between these
mountain ranges are not complete, so the system is prolonged
by successive ranges to and beyond the southern boundary of
California.

Another of these topographic districts is the northern part
of southeastern California; this is composed of narrow and
parallel mountains and valleys running north and south. The
mountains are high, and the valleys narrow and closed. Farther
to the south the relief is composed of irregularly grouped and
rather low mountains, flat intervening table-lands and closed
drainage basins.

The Sierra Nevada.—The Sierra Nevada is essentially a single
mountain chain with a summit line deviating but little from the
general trend of the mountains. This summit line is near the
eastern edge of the range, except in the extreme northern part
where it extends nearer to the western limit of the mountains.
The eastern slope of the mountains is especially abrupt. The
fall from Mt. Whitney to Owen’s Valley, a distance of ten miles,
is about 10,000 feet.t The western slope approximates a long,
broad, inclined plain, furrowed deeply and closely by numerous
canyons. By observing the accompanying plate it may be seen

‘J. D. WHITNEY, Geological Survey of California, Vol. I, p. 456.

THE TOPOGRAPHY OF CALIFORNIA 567

that if these canyons were filled level to the tops of the ridges
the result would be an irregular, slightly warped, tilted plain.
In general the grade of this tilted plain is quite regular from
the low elevation of the California Valley to the top of the moun-
tains. This western slope was probably once a region worn
down almost to base level or to a peneplain. By the uplift of
the mountains a great fault was developed along the eastern face
and the whole Sierra crust-block tilted to the westward. The
streams quickened by the uplift again set to work on the pene-
plain and carved it to its present condition. According to Pro-
fessor Joseph Le Conte :*

The Sierra was formed, as we now know, by lateral crushing and strata-
folding at the end of the Jurassic. But during the long ages of the Creta-
ceous and Tertiary this range was cut down to very moderate height. ....
The rivers by long work had finally reached their base-levels and rested.
The scenery had assumed all the features of an old topography, with its
gently flowing curves. .... At the end of the Tertiary came the great lava
streams running down the river channels and displacing the rivers ; the heav-
ing up of the Sierra crust-block on its eastern side, forming the great fault-
cliff there and transferring the crest to the extreme eastern margin; the
great increase of the western slope and the consequent rejuvenescence of the
vital energy of the rivers; the consequent down-cutting of these to form the
present deep canyons and the resulting wild, almost savage, scenery of these
mountains.

J. S. Diller’s researches in the northern part of the Sierra
Nevada further strengthen these theories, as the following quo-
tations from him will show:

A study of the ancient topographic features upon the borders of the
Sacramento valley, in the Klamath Mountains, and upon the western slope of
the Sierra Nevada, shows that during the earlier portion of the auriferous
gravel period northern California, by long-continued degradation, was finally
reduced approximately to base-level conditions. The mountain ranges were
low, and the scenery was everywhere characterized by gently flowing slopes.
.... The topographic revolution consisted in the development out of such
conditions of the conspicuous mountain ranges of today. The northern end
of the Sierra Nevada has since been raised at least 4000 feet, and possibly as
much as 7000 feet, and a fault of over 3000 feet developed along the eastern

* Bull. Geol. Soc. Am., Vol. II, pp. 327-328.

568 NOAH FIELDS DRAKE

face of that portion of the range... . . The amount of uplift decreases rap-
idly towards the Sacramento valley.”

Mr. Waldemar Lindgren thinks the Sierra Nevada was eroded
to, or almost to, a peneplain during Cretaceous times, and that
the mountains elevated ina later Cretaceous period were worn
down during Tertiary times merely to a gentle topography.”

Of the origin of the range he says:

At this time’... . the first break took place, separating the Sierra
Nevada from the interior basin. The orogenic disturbance was probably of
a twofold character. It included the tilting up of the whole region between
the Wasatch and the Pacific in arching form, and a simultaneous breaking in
and settling down of the higher portions of the arch. Thus the Sierra
Nevada crust fragment was formed, the larger part of which has ever since
remained a comparatively rigid block. Along the eastern margin the sys-
tem of fractures was outlined which toward the close of the Tertiary was to
be still further emphasized.

The evidences that the Sierra Nevada is a tilted and eroded
peneplain with a fault line along its eastern edge may be summed
up as follows:

(1) The present features of the western slope of the moun-
tains resemble a tilted and dissected peneplain. The precipitous
slope on the eastern side marks the fault line.

(2) Fossil plants, which indicate a low altitude at the time
of the deposition, have been found in the auriferous gravels in
the northern part of the Sierra Nevada.

(3) The auriferous gravels now found in the old river beds
along the western slope of the Sierra Nevada must have been
deposited in streams flowing down gentle grades.

(4) Many of the old river valleys are terraced, showing suc-
cessive stages of elevation as well as low stream grades.5

(5) The present rivers flow directly across the upturned edges

14th Ann. Rept. U.S. Geol. Surv., Part II, p. 433.

2Jour. GEOL., Vol. IV, pp. 882, 894, 897, and 808.

3JouR. GEOL., Vol. IV, p. 894.

4J.S. DILLER, 14th Ann. Rept. U. S. Geol. Surv., pp. 421-422.
5J. S. DILLER, 8th Ann. Rept. U. S. Geol. Surv., Part I, p. 429.

THE TOPOGRAPHY OF CALIFORNIA 569

of Mesozoic and Paleozoic beds on the lower slopes of the
mountains.

(6) The Tertiary lavas on the western slope of the Sierras
cover a gentle topography."

It has been noted that the Sierra Nevada is now deeply
carved by the streams flowing down its western slope. The
canyons vary in depth from a few hundred to six thousand feet ;
their walls are very steep, and in places perpendicular; in the
Yosemite and King’s River canyons there are perpendicular walls
over three thousand feet high.? These canyons run approxi-
mately at right angles to the trend of the mountains and parallel
with each other. This direction and parallelism is especially
true of the larger canyons, which form a series quite regularly
spaced throughout the length of the mountains.

The parallelism of the canyons is due principally to the two
causes of uniform direction of tilting and the parallel system of
fault and fissure lines. It is generally conceded that the great
canyons, as well as many smaller ones, run along fault lines.

And it has been observed*+ that often the canyon following
one system of fissures crosses over to another system and fol-
lows it. G. F. Becker has pointed out that in places these
fissure lines are so close together as to amount to shattered
zones, and that the main fissure systems cross at right angles.‘

So a probable explanation for such places as King’s River
and Yosemite Valleys is that they are the locations of shattered
zones removed by erosion, so that the fissures bounding the
shattered zone now form the faces of the perpendicular exposed
valley or canyon walls.

It may be seen from the accompanying plate that the can-
yons west of Lake Tahoe, especially North Yuba River, Middle

WALDEMAR LINDGREN, JOUR. GEOL., Vol. IV, p. 897.

2J. D. WHITNEY, Geol. Surv. Calif., Vol. I, pp. 410 and 421. JOHN MuIR, Cen-
tury Magazine, Vol. XVIII, p. 488, and Vol. XXI, p. 80.

3G. F. BECKER, Bull. Geol. Soc. Am., Vol. II, p. 68. The Rocks of the Sierra
Nevada, by H. W. TuRNER, 14th Ann. Rept. U. S. Geol. Surv., p. 443.

4G. F. BECKER, Bull. Geol. Soc. Am., Vol. II, p. 68.
5 Bull. Geol. Soc. Am., Vol. II, pp. 50-51 and 68.

570 NOAH FIELDS DRAKE

Yuba River, Bear River, North Fork and Middle Fork of Amer-
ican River, receive almost all their drainage from the north
side, which would seem to indicate that each of these main
canyons followed a fault line, and that in addition to the west-
ward tilting of the mountain mass these separate smaller blocks
between the canyons tilted to the southward also.

The regularity of the canyon system and the westward-
sloping, eroded plain is somewhat more broken to the south of
Merced River, where the principal rivers, z. e., the San Joaquin,
the Kings, the Kaweah, and the Kern, have a wide range of
tributary streams and have carved out more basin-like drainage
areas. It appears that the southern end of the Sierras has
existed longer as a mountain range; and also that the Tertiary
lava flows that spread over northeastern California as far south
as Merced River did not bury the drainage systems farther to
the south. Thus it seems that these drainage systems are
older and naturally more basin-like or collected in larger
groups.

The Kern River is the first to break the general westward
course and flow south for most of its length before turning
towards the California Valley. The parallelism in the tribu-
taries of the upper course of the Kern forcibly suggests faulting
and folding along parallel north and south lines, and probably
southward tilting also, to guide the streams.

Cascade region.—The northeast part of California is a table-
land with cone-shaped peaks here and there rising above the
general level. Toward the east the flat table-lands are broken
by ridges extending north and south which usually have a steep
slope on the east side and a gentle slope on the west side. The
lava outflows that spread over southeastern Oregon extend in a
sheet over this area forming the table-land. The cone-shaped
peaks are lava outpourings, where the lava flows were concen-
trated at points. Mt. Shasta and Lassen peaks are notable
examples of volcanic cones on the western side of this area.
In the northeast corner of this area fault lines are prolonged
southward from a fault system extended down from southeastern

THE LOPOGRAPHY OF ‘CALIFORNIA 571

Oregon.* Small orographic blocks between these fault lines are
usually tilted westward and form ridges and basins such as
Warner Mountains, Alkali Lakes basin, and Goose Lake basin.

Klamath Mountains —To the west of the lava sheet lies the
irregular group of mountains known as the Klamath Mountains.

This region has long been subjected to erosion, and to oscil-
lations? from archipelago to high land elevations. The outpour-
ing of lava and accumulations of sedimentary beds on the flanks
of the granitic core and the irregular tilting, and faulting, have
produced a complex mountain mass and an area of tortuous
stream courses.

The Coast Ranges.—Joining the Klamath Mountains on the
southwest, and extending southward along the coast are the Coast
Ranges. The typical part of this system lies west of the Califor-
nia Valley. This part of the Coast Ranges is composed of
numerous parallel ranges, ridges, valleys, and canyons which
extend in almost straight lines along and parallel with the coast.
The elevations of opposite ranges are usually approximately the
same. At places the opposite ranges are completely separated, but
usually they coalesce, only to break again along the same lines.
Thus along any given line through and parallel with the ranges, a
topographic feature may disappear but it occurs again after a short
break. These parallel lines of topographic features show the
close kinship of the ranges and extensive fault lines and folding
axes.

tJ. C. RUSSELL, A Geological Reconnaissance in Southern Oregon. 4th Ann.
Rept. U. S. Geol. Surv., pp. 436-464.

2“ At the close of the Taylorville Jurassic there was an upheaval by which the
Klamath Mountains were outlined.””—J.S. DILLER, Bull. Soc. Am., Vol. IV, p. 224.

“During the Cretaceous period, especially during that portion represented by the
Shasta-Chico beds, northern California gradually subsided.... . The Klamath
Mountains during a part of this time, at least, formed an island.”—J. S. DILLER, Ter-
tiary Revolution in the Topography of the Pacific Coast. 14th Ann. Rept. U.S. Geol.
Surv. 1892-3, pp. 23-24.

“During Miocene times .... the Klamath Mountains were low with gentle
slopes as compared with those of the present ranges; and the streams flowed down
their flanks in broad shallow valleys instead of in deep canyons as they do now.”’—JourR.
GEOL., Vol. II, p. 44; also 14th Ann. Rept. U. S. Geol Surv., p. 423.

572 NOAH FIELDS DRAKE

Lawson has shown? that a considerable part of this region
has been eroded to base level and when this area was elevated
to a plateau, erosion followed the weak lines, dissecting the
plateau until only the tops of ridges are now left as evidence of
the once leveled region. The larger ranges and valleys, how-
ever, appear to be of orogenic rather than erosive origin. Local
shifting of land elevations or the irregular tilting of some small
blocks of the earth’s crust has divided some of the larger val-
leys such as Russian River—Petaluma Valley, and the Santa
Clara-San Benito Valley.. In both cases the adjoining valleys
are continuous, but from tilting of earth-crust blocks the valleys
are slightly divided so that their drainage runs into the ocean or
bays at different places. An elevation of the southern end of
the Santa Clara Valley has turned the San Benito River to one
side so that it now flows through a narrow outlet into the Bay
of Monterey instead of continuing in the straight and open val-
ley to the north and emptying into San Francisco Bay. Simi-
larly the southward continuation of the Russian River Valley
leading into San Pablo Bay is so tilted as to throw the Russian
River drainage to one side through a narrow outlet into the
ocean. Such local tilting of the earth’s crust causing the flood-
ing of valleys is the origin of San Francisco Bay, Tomales Bay,’
and probably? Monterey Bay. This shifting has been so late
that the effects of subsidence are plainly shown in adjoining val-
leys. Tomales Bay‘ is clearly one of these drowned valleys.
It is a long riverlike bay that is about three-quarters of a mile in
width and fifteen miles long. The valley of the bay continues
to the southward until it reaches the ocean again.

The great valley of Californa.—The California Valley, lying
between the described mountain systems, is a low, level area
about 400 miles long and 50 miles wide. The width of the val-
ley is quite regular throughout, but is somewhat greater at the
southern end and a little north of the center. At this latter

* Bull. Dept. Geol. Univ. Calif., Vol. I, No. 8, pp. 242-244.

? A. C. Lawson, Bull. Dept. Geol. Univ. Calif., Vol. I, pp. 263-269.

3A. C. Lawson, Bull. Dept. Geol. Univ. Calif., Vol. I, p. 59.
4A. C. Lawson, Bull. Dept. Geol. Univ. Calif., Vol. I, No. 8, p. 264.

THE TOPOGRAPHY OF CALIFORNIA 573

place the San Joaquin and Sacramento rivers, which are the
principal streams of the valley, are confluent and flow westward
through the straits of Carquinez, thence through San Francisco
Bay into the ocean. Well borings at different places over the
valley show the upper 1000 feet or more of the valley deposits
to be fluviatile and subaérial,' for the strata consists of alternat-
ing beds of sand, clay, and gravel, and in places contain loess-
like? strata and organic remains} of land and fresh water animals.

The origin and growth of the valley, as stated by F. L. Ran-
some, is in brief as follows: 4

With the post-Pliocene elevation of the crest of the Sierra and with the
gradual upward diastrophic movement of the Coast Ranges during Pleistocene
times . . . . the valley became closed in by mountains as we find it at the
present day i... s 6

All through Pleistocene and recent times, the streams flowing down from
the Sierra, and from the eastern slope of the coast ranges have been pouring
detritus into the deepening valley, depositing the coarser materials in broad
alluvial fans and carrying the finer silt farther out to be spread over the plain
in flood seasons.

So it seems that this area has been largely built up at equal
pace with its subsidence, usually existing as a low, marshy tract,
retaining a large part of the detritus brought down from the
Sierras and Coast Ranges. The southern end of the valley is a
low, marshy area, with no well-defined outlet, and at the present
time retains all the detritus and sediment brought there from the
adjoining mountains.

The Sterra Madre Mountains.—\t has been noted that west of
the California Valley the axes of the coast ranges run nearly
northwest and southeast, but the further continuation of the
coast ranges to the southward is first marked by almost east and

west axes, which are in turn followed by ranges running north-
west and southeast. In each case the coast line turns and runs

parallel with the axes of the mountains along the coast. The

«Eighth Ann. Report Calif. State Mineralogist, 1888, pp. 558-560 ; Tenth Report,
1890, pp. 548-564; Twelfth Report, 1893, pp. 350-351.

? Bull. No. 3, Calif. State Mining Bureau, p. 16.

3 Bull. No. 3, Calif. State Mining Bureau, pp. 20 and 68.

4The Great Valley of Calif., Bull. Dept. Geol. Univ. Calif., Vol. I, p. 398.

574 NOAH FIELDS DRAKE

islands off the coast of southern California have their longer
axes lying in the same direction as the opposite shore line and
mountain range, showing that these islands belong to the sys-
tem of orogenic movements that created the mountain ranges of
the mainland and are remnants of partly submerged mountain
ranges.

The parallel grouping of mountain chains, which is so prom-
inent a feature of the Coast Ranges to the north, is much less
marked in the Sierra Madre Mountains, where the mountain sys-
tem consists essentially of successive single ranges, somewhat
elongated in the axial direction, but consisting of a central mass,
from which spurs radiate in all directions.

Owens River—Death Valley district.—This topographic region
is the southern end of the Great Basin mountain system. The
mountains and valleys of this system are parallel and run north
and south. The mountains are usually high, and the valleys low
and narrow. This topography is one of block faulting, which
gives the great extremes in elevation and the narrow straight
lines of mountain ranges and valleys. Drainage is now poorly
defined, because the rainfall is so light that no permanent streams
of any considerable length exist. Nearly every valley is a closed
basin that has been filled to a considerable depth with detritus
from the adjoining mountains. Death Valley, though having
this usual filling of detritus, is, at its lowest place, 480 feet*
below sea level.

Mohave—Colorado River district—Southeastern California has
rather low, irregular-shaped mountains, flat table-lands, and low,
closed drainage basins. Nearly all the mountains and hills have
the appearance of being partially buried, so that only their tops
project, island-like, above the surrounding plains. In this region
there is but little or no drainage to carry off the disintegrated
rocks. The débris, blown and drifted around, fills the valleys

until only the tops of the hills project above the débris-covered
plain. This area is a meeting point for several mountain sys-

tems, and therefore has a mixed arrangement of its mountains.

*North American Fauna, No. 7, Death Valley Expedition, Part II, p. 367.

THE TOPOGRAPHY OF CALIFORNIA 578

MINOR TOPOGRAPHIC FEATURES.

Besides the general topographic features which may be seen
from the accompanying plate, there are others too small to show,
but nevertheless of considerable importance.

Terraces —There are, along almost the whole length of the
coast, benches and rounding bluffs of more or less prominence.
Some of these terraces are only seen after close observation,
while others form benches of considerable width.

As shown by Lawson," these are marks of old seashores, and
show successive elevations of the land through Quarternary
times.

Mesas and table-lands——TYhese are marked features of the
coastal plain north of San Diego, and occur on the sides of river
valleys farther to the north. This characteristic feature may be
observed in the Salinas Valley at King City. Lawson has shown?
that the Pliocene corresponds to a time of general subsidence
of the coast, when the sea encroached upon the land, flooding
the low coast lands and valleys. These flooded coast margins
and valleys thus became the dumping ground for the sediment
from neighboring lands until the accumulations grew to great
thickness. Then, when the land rose and erosion carved this
accumulated sediment, mesas and table-lands were left.

Alluvial cones and fans.—In parts of the state where the rain-
fall is light or not sufficient to carry the disintegrated rocks any
considerable distance it is common to see along the valleys, at
the mouths of mountain canyons, the valley built up higher, so
that the mouth of the canyon is buried beneath a cone of débris.
The writer has observed this in the White Mountains near the
California-Nevada state line, where, standing at a commanding
place some five or six miles from the mouth of a large canyon,
it seemed as if all the débris removed to cut out the canyon had
been distributed at the mouth of the canyon and extended in

tBull. Dept. Geol. Univ. Calif., Vol. I, Nos. 1, 4 and 8.

2 The Geology of Carmelo Bay, Bull. Dept. Geol. Univ. Cal., Vol. I, No. 1.
The Post-Pliocene diastrophism of the Southern Coast of Calif., Bull. Dept.
Geol. Univ. Cal., Vol. I, No. 8.

576 NOAH FIELDS DRAKE

decreasing amount for two or three miles into the valley and to
the right and to the left along the mountain side. This feature is
beautifully shown on some of the United States Geological Survey
topographic sheets* of southern California, where at the mouths
of large canyons, such as the San Gabriel, instead of the contours
running up towards the canyon, they circle around or away from
it. Where the rainfall is somewhat greater the débris is carried
further and distributed over a wider area, forming a fanlike
extension of sediments. This feature has already been referred
to in the discussion of the California Valley.

Superimposed drainage —Near the head of Salinas Valley or
immediately south of Santa Margarita, there is a valley from
one to two miles wide underlaid by rather soft Tertiary sand-
stones and shales. To the east of the valley there is a granitic
mountain range nearly 2000 feet high, while to the west there is
a parallel range about 3000 feet high which is composed of
rather soft Tertiary shales and sandstones. The Salinas River,
instead of running through this valley, runs close by and paral- -
lel to it through a narrow deep canyon in the granitic mountain
range. One stream in particular, and others to some degree,
that run down from the western or sedimentary range of moun-
tains, follow the valley for a few miles and then cut through the
granitic hills by narrow canyons and flow into the Salinas River.
The divides in the valley deflecting the streams are only about
100 feet? above the bed of the river while the narrow strip of
granitic hills cut off between the river and valley, rises six and
seven hundred feet above the river bed.

It seems most probable that in this case the soft sandstone
and shales originally extended over the granitic mountains, as
well as the valley and mountains to the west, and that the river
was originally situated vertically over its present course, so that
it has carved its way down through the soft covering and thence
into the granite, and has so far kept below the more recent
erosion-valley in the soft beds by its side.

*The Cucomonga and San Bernardino sheets of the U. S. Geol. Survey.

?See San Luis Obispo sheet U. S. Geol. surv. maps, surveyed in 1895.

THE TOPOGRAPHY OF CALIFORNIA 577

EFFECTS OF VEGETATION ON TOPOGRAPHY.

Sand dunes.—During the summer of 1895 the writer assisted
in mapping a number of sand dune areas along the coast in San
Luis Obispo county. In all these areas there seemed to be no
exception to the rule that where the sand was free from vegeta-
tion or obstruction, it was piled in ridges at right angles to the
prevailing sea breezes, and that where patches of vegetation
grew the dunes became parallel to the direction of the wind,
and where the vegetation became thicker over the ground, the
regularity of arrangement of the dunes was more broken. It
seems that the change in direction of the dune ridges (from
right angles to parallel with the winds where vegetation began),
is due to the fact that vegetation once started would check the
sand from moving at that point and make a shelter for deposits
to the leeward. This point of the sand dune now being more
stable, other plant growth would spring up, mainly on the iee-
ward side, so as to lengthen and increase the elevation of the
ridge while the unprotected sands at either side would drift
away, thus forming narrow parallel ridges in the direction of
the prevailing winds. Ridges fifty to seventy-five feet high and
400 to 600 feet long, or even longer, were not uncommon where
the sand dunes are extensive.

Fiill slopes —While mapping over the area south of San Luis
Obispo for some twenty or twenty-five miles, it was observed
that the slope of the north side of the hills was steep while that
of the south side was gentle. This proved to be almost invaria-
bly true, no matter in what direction the strata dipped or
whether the underlying rock was loose sand.

This part of California, like most of the state, has a dry sea-
son and a wet one. During late spring, all summer, and early
fall there is no rain and therefore any shelter from the sun’s
heat insures thicker and more permanent growth. So the north
sides of the hills are more thickly covered with vegetation,
especially perennial growths, and timber is often completely
confined to them. The roots, leaves, and débris of the vegeta-
tion would protect the soil from washing away, while on the

578 NOAH FIELDS DRAKE

south side of the hills the almost barren ground would lose
much of its soil at every freshet. Over most of this area erosion
is lowering the hill tops about as fast as stream corrasion lowers
the creek beds. So the vertical distance between hill top and
stream bed remains nearly the same, while the horizontal dis-
tance on the north side of the hill becomes less because the hill
top recedes to the north as its south side is the principal one to
be trimmed back by erosion. Such a process would in time
almost produce a bluff. Suchsteep hill-sides may be seen
immediately east of Arroyo Grande along the south side of Tar
Springs Creek, San Luis Obispo county.

Topography as modified by rainfall—tn southeastern Cali-
fornia where it is especially arid, there is almost no vegetation
to hold the soil and disintegrated rock in place, so the weathered,
loose, rock-fragments are soon blown to low ground leaving the
rocks of the hillsides exposed in rough angular forms and the
topographic outlines strongly fixed by the character of the rock
mass or strata.

In the humid portion of the state, however, vegetation holds
the soil from washing or drifting away and as the rocks con-
tinue to disintegrate, the hills are covered and rounded off by
this mantle of soil and débris. Besides this reason for the roll-
ing character of the topography, the following causes may be
added: The sedimentary rocks as a rule are soft and much
broken by numerous fissures, faults, and folds, so hard and fast
lines or horizons to resist weathering do not often exist. The
igneous rocks are usually great masses and necessarily show
their characteristic rolling topography.

Taken as whole probably the most characteristic feature of
the topography of the Pacific Coast is the rolling nature almost
everywhere seen where relief is shown. This feature is espe-
cially impressive to one familiar with the bench, bluff, and flat
topped mountain topography of the Mississippi valley region.

NoauH FIELDS DRAKE.

STANFORD UNIVERSITY,
California.

im COMPARATIVE SEUDY OF THE, LOWER, CRETA-
CEOUS, FORMATIONS AND FAUNAS, OF THE
CNITED STATES?

,INTRODUCTION.

BEsIDEs the facts of wide distribution and economic impor-
tance the Cretaceous is notable for the problems of more purely
scientific nature than it presents. For example, near the middle
of Cretaceous time or at the beginning of the neo-Cretaceous
(to adopt William’s term) there was a great transgression of the
sea upon the land—perhaps the greatest and certainly one of the
most clearly recorded extensive one in geologic history. During
the Trias and Jura almost all the present area of the continent
was above sea level, as is shown by the absence of marine strata
of those periods, excepting in limited areas of the Rocky
Mountain and Sierra Nevada regions. The advance of the sea
commenced with the Cretaceous, covering nearly all of Mexico
and extending northward in the United States to southern
Kansas, besides encroaching on the coast range region in the
West while the lower Cretaceous sediments were forming.
Then there was a greater and more rapid advance until at its
maximum extent the sea covered almost the entire area between
the Mississippi River and the Wasatch range, extending north-
ward to the Arctic Circle. It also washed the western slope of
the Sierra Nevada and covered the entire coastal plain of the
Atlantic and the Gulf. The advance was not continuous nor
constant, however. There were retrograde movements so that
locally fresh-water and brackish-water deposits with associated
coal beds are interstratified with the marine formations. Before
the close of the Cretaceous while the Laramie beds were being

tThesis submitted in partial fulfillment of the requirements for the degree of

Doctor of Philosophy in Columbian University, Washington, D. C., June 1897.
579

580 TIMOTHY WILLIAM STANTON

laid down the sea had retreated from most of the continental
area and it has never since invaded it beyond the coastal border
regions. It is a noteworthy fact, as Neumayr* and others have
pointed out, that there was a similar invasion of the sea upon
the other continents in mid-Cretaceous time.

The occurrence of contemporary marine, fresh-water and
brackish-water formations has greatly complicated the classifica-
tion and correlation of the Cretaceous beds. Deposits formed
under such diverse conditions naturally have few features in
common, either lithologically or paleontologically, and their
correlation must usually depend on similarity of stratigraphic
and structural relations with formations of known age. Ina few
cases, however, the same flora and other land organisms have
been preserved in both marine and fresh-water beds, and have
thus demonstrated their practical contemporaneity.

Besides the sharp contrasts between marine and non-marine
beds there are several distinct facies within the marine Creta-
ceous formations. Whether the paleontological differences are
due to climate, to isolation, to differences in depth or in the
nature of the sea bottom, are questions that should be solved
independently in each case, but their solution is usually diffi-
cult. The first essential is to determine that the formations
compared are actually contemporaneous or homotaxial. A
failure to do this has led to serious errors in the past. For
example, Roemer? noticed that the Cretaceous fauna of New
Jersey is very different from that found in Texas in beds that he
supposed to be contemporaneous. He also noticed that the
former corresponded rather closely with the Cretaceous fauna of
northwestern Germany, while the Texan fauna found its nearest
analogues in the Cretaceous of southern Europe bordering on
the Mediterranean. He concluded, therefore, from these geo-
graphic relations that the faunal differences were due mainly to
climate, that the present climatal zones were already established
in Cretaceous) time and. even {that “the ocean ‘currents had

t Erdgeschichte, Bd. 2, p. 377.
2 Am. Jour., Sci. 2d. ser., Vol. II, 1846, p. 364. Kreideb. v. Texas, 1852, p. 25.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 581

approximately their present positions, since the European
localities are respectively several degrees farther north than
their American analogues, corresponding to the position of
isothermal lines on opposite sides of the Atlantic at the present
time. This was one of the first attempts to establish climatal
zones at such an early period, as it was published even before
von Buch’s* generalization that the absence of Cretaceous faunas
in the polar regions is due to the climatic conditions of that
period. In Neumayr’s studies of Mesozoic climates use was
made of the difference between the Cretaceous faunas of New
Jersey and Texas, and it has recently been cited by Kayser? and
by J. Perrin Smith.3 There is some evidence of the existence of
climatal zones in the Cretaceous and even earlier in Mesozoic
time, but Roemer’s original examples should no longer be cited
as proof, for it is now known that the faunas Roemer compared
were not contemporaneous, the base of the marine Cretaceous
beds in New Jersey being somewhat newer than the uppermost
horizon that furnished the fossils he described from Texas. If
he had made his comparisons with the Ripley fauna, which
occurs near the top of the Texan Cretaceous and only a few
miles east of the beds studied by him, Roemer’s conclusion
would probably have been very different, for a very large per-
centage of the species are identical with the New Jersey forms,
and there is nothing suggestive of a warmer climate.t The
Upper Cretaceous faunas of the Atlantic and Gulf border regions,
when comparison is made with strictly homotaxial zones, are
remarkably uniform along the whole coast from Texas to New
Jersey.

The correlated faunas of the Rocky Mountain region and
the great Plains show much greater differences when compared
with the faunas just mentioned, and these may reasonably be

tVerbreitung und Grenzen d. Kreidebildungen. Verhandl. des Naturhist. Vereins
d. Preuss. Rheinlande u. Westphalien, Bd. 7, pp. 211-242.

2Text-book of Comparative Geology, translated by Lake, p. 283, Lond., 1893.

3 Jour. of GEOL., Vol. III, p. 485, Chicago, 1895.

4See WHITFIELD; Bull. Am. Mus. Nat. Hist., Vol. II, 1889, pp. 113-116 and
WHITE, Bull. U. S. Geol. Surv., No. 82, pp. 84, I11.

582 TIMOTHY WILLIAM STANTON

attributed in part to the influence of climate, but it would carry
us too far from our subject to discuss this question fully.

The life of the Cretaceous period offers many other points of
general interest, chief among which is the fact that while it is
essentially Mesozoic in character, and is thus allied with the life
of earlier periods, it nevertheless includes the earliest recorded
repres ntatives of very many recent generic and family types
and some groups of higher rank, and in the later stages this
modern element is often relatively large. This statement refers
chiefly to plants and invertebrates, for, with the exception of
the Teleost fishes, which are introduced for the first time, the
vertebrates nearly all belong to types now extinct or of rela-
tively little importance. So far as the record goes the great
group of placental mammals was not yet introduced, and the
vertebrate fauna consists largely of Mesozoic types of reptiles,
such as dinosaurs, pterosaurs and pythonomorphs, with a few
small mammals of the lowest groups, and birds of archaic types.

Among the invertebrates the Ammonoidea are very greatly
differentiated and finally become extinct with the close of the
period. Many other forms, such as Inoceramus, certain types
of Ostreidae, Nerinea, Anchura, Pugnellus, etc., do not pass the
upper limits of the Cretaceous. On the other hand, the Ostre-
idae, Anomiidae, Mytilidae, Unionidae, Veneridae, Mactridae,
Turritellidae, Naticidae, Volutidae, etc., are represented by
forms closely related to living species. The flora is completely
revolutionized and modernized during the Cretaceous. Early in
the Cretaceous the first Dicotyledons occur and by mid-Creta-
ceous time they largely predominate and numerous genera of
trees that time still live in our forests are already introduced, so
that the biologist who is studying recent species must often go
back to the Cretaceous faunas and floras to complete his data
for a rational classification.

RECOGNITION OF THE LOWER CRETACEOUS IN THE UNITED STATES.

Before going farther it may be well to recall the general clas-
sification of Cretaceous deposits as adopted in Europe. It is

LOWER CRETACEOUS FORMATIONS AND FAUNAS 583

now customary to recognize only two principal divisions — Lower
Cretaceous and Upper Cretaceous — instead of three as formerly.
The number and nomenclature of the subdivisions varies in dif-
ferent countries and with different authors, but the terms Neoco-
mian, Urgonian, Aptian, Albian, Cenomanian, Turonian, Senonian
and Danian proposed by d’Orbigny are frequently used and
universally understood.

In Neumayr’s Erdgeschichte* the following arrangement is

adopted:
Upper Cretaceous. Lower Cretaceous.
Senonian. Gault.
Turonian. Aptian.
Cenomanian. Neocomian.

In this classification of the Lower Cretaceous the Wealden
is treated as simply a non-marine facies of the Neocomian,
the Urgonian is made a subdivision of the Neocomian (as
it was by d’Orbigny also) and the English name Gault is sub-
stituted for Albian. Some authors place the Gault in the Upper
Cretaceous, but for comparison with American formations it is
more satisfactory to classify it with the older beds.

These minor subdivisions are not applicable to the American
Cretaceous excepting in the most general way, and, as Dr.
White has insisted, it is not probable even that the correspond-
ing principal divisions as recognized on the two continents are
strictly homotaxial, but the accumulating evidence tends to show
that the difference is not very great. In making an independent
and natural classification of our formations we have perhaps
placed a few beds in the Lower Cretaceous that by European
standards would go in the Upper Cretaceous.

The first definite recognition of Lower Cretaceous in this
country based on good evidence was by Professor Jules Marcou,?
who in 1855 identified a number of fossils from Texas as Neoco-
mian, and asserted that rocks of that age cover considerable

* Bd. 2, p. 344.

? Pacific R. R. Reports, 8vo edition, Vol. IV, pp. 40-48, 1855; republished in 4to
edition and in Geology of North America.

584 TIMOTHY WILLIAM STANTON

areas in Texas and Indian territory. Marcou has maintained the
correctness of his determination in numerous subsequent papers,
but for various reasons his opinion, though essentially correct,
did not meet with general acceptance for many years. The
principal causes that conspired to prolong this misconception
were (1) Marcou’s own error in referring to the Jurassic certain
New Mexican exposures of a part of the same series; (2)
Roemer’s previously published important work, ‘Die Kriede-
bildungen von Texas,” in which on paleontological grounds all the
Texan Cretaceous beds were referred to the Upper Cretaceous ;*
(3) the publication of Shumard’s? section in which the strati-
graphic succession is very erroneously given, and (4) the fact
that the investigation of other regions in the United States did
not reveal any Lower Cretaceous beds that were really compara-
ble with those of Texas. The subject remained thus until 1887
when the publication of papers by Dr. C. A. White3 and Mr. R.
T. Hill,4 based on the latter’s field work, established the fact that
there is in Texas a great series of Cretaceous rocks underlying
the generally recognized Upper Cretaceous of other parts of the
country. This is the Comanche series that has since become so
familiar through the numerous papers of Mr. Hill.

« The idea has been current for some years that ROEMER’S principal error was a
stratigraphic one in placing his “‘ Cretaceous of the Highlands” above the “‘ Cretaceous
at the foot of the Highlands” as he did tentatively in his earlier work ‘“‘ Texas,” but a
careful perusal of the introductory pages—especially page 19——of the “ Kreibil-
dungen” will show that he did not finally attempt to establish any stratigraphic
succession, and that he admitted that there were both paleoritologic and physical
reasons for regarding the beds of the Highlands as older than the others, and he
suggested that their topographically higher position might have been caused by a
fault. His real error was that in his paleontological comparisons with the Cretaceous
of southern Europe, he did not recognize the now well-known fact that there are two
distinct horizons, one in the Upper Cretaceous and the other in the Lower, each char-
acterized by peculiar species of Rudistae, Chamidae, etc.

2Trans. Acad. Sci., St. Louis, Vol. I; pp. 582-589, 1856-1860.

3On the Cretaceous formations of Texas and their relations to those of other parts.
of North America. Proc. Phila. Acad. Nat. Sei., 1887, pp. 39-47.

4The topography and geology of the Cross Timbers and surrounding regions in
northern Texas. Am. Jour. Sci., 3d ser., Vol. XXXIII, pp. 291-303, pl. 6. The
Texas section of the American Cretaceous. Am. Jour. Sci., 3d ser., Vol. XXXIV;
1887, pp. 287-319.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 585

Some years before the investigation of the Texan Cretaceous
was begun several geologists described strata in Virginia, Mary-
land, Delaware, and New Jersey that are now usually referred to
the Potomac formation, but they had few facts on which to base
their age determination. Thus W. B. Rogers* described these
beds as Upper Secondary, and provisionally referred them to the
Upper Jurassic, though he later? suggested that they might form
a ‘‘passage-group analogous to the Wealden of British geology.”
Tyson also described a part of the same series under the desig-
nation of ‘iron ore clays’’ which he at first referred to the Cre-
taceous, but afterward‘ placed ‘‘at least as low as the Oolitic.”
According to Dawson’ and Fontaine® Tyson considered that
these beds belonged to the Wealden, but he seems not to have
published that opinion. In 1886 Mr. W J McGee’ named and
described the Potomac as a distinct formation including the
above mentioned beds that had been discussed by Rogers and
Tyson. Its determination as of Lower Cretaceous age has been
mainly due to the paleobotanical work of Professors L. F.
Ward? and W. M. Fontaine.?

In 1869 Gabb and Whitney’ defined the Shasta group of
California, stating that ‘It contains fossils seemingly represent-
ing ages from the Gault to the Neocomian, inclusive.” The
Shasta group has ever since been referred to the Lower Creta-
ceous, and subsequent investigations have only confirmed the

* Report of Prog. of Geol. Surv. of Va. for 1840, Richmond, 1841. Idem for
1841, Richmond, 1842. Both reprinted in Geology of the Virginias, 1884, pp. 413-
546.

2 Proc. Bost. Soc. Nat. Hist., Vol. XVIII, 1875, p. 105.

3 First Rept. State Agricultural Chemist of Md., pp. 41-43, Annapolis, 1860.

4Second Rept. State. Agri. Chemist, p. 54, Annapolis, 1862.

5 Trans. Roy. Soc. Canada, Vol. III, 1885, sec. 4, p. 18.

6 Monograph U. S. Geol. Surv., No. 15, p. 5.

7Rept. of Health Officer for the Dist. of Columbia for 1885, pp. 23-25; Am.
Jour. Sci., 3d ser., Vol. XX XV, 1888, pp. 120-143.

8 Am. Jour. Sci., 3d ser., Vol. XXXVI, 1888, pp. 119-131.

9 Monograph 15, U.S. Geol. Surv., 1889. See also many subsequent articles by
both authors and by McGkrE, DarToN, WHITE, MARSH, and CLARK listed in the
accompany bibliography.

to Paleeont. of California, Vol. II, p. xiv.

586 TIMOTHY WILLIAM STANTON

original suggestion as to its age. The stratigraphy and pale-
ontology of the Shasta beds have been described or discussed
by Gabb, Becker, White, Diller, Turner, Fairbanks, and Stanton.

Soon after the definition of the Shasta, Richardson? described
strata in the Queen Charlotte Islands that were recognized by
Billings from the invertebrate fossils as in part the equivalent of
the Shasta, and on the evidence of a few plants were assigned
to either the Jurassic or the Lower Cretaceous by Dawson. The
fauna of these beds and of their equivalents on the mainland of
British Columbia has since been described by Whiteaves, who
regards them as not later than the Gault.

A few years later a series of fresh-water coal-bearing beds,
the Kootanie formation, in the Rocky Mountain region of south-
ern Canada, was recognized and defined by Dr. Geo. M. Daw-
son. The accompanying flora was studied by Sir William Daw-
son, who determined its age to be Lower Cretaceous and pub-
lished the first account? of the formation in connection with the
description of the flora. In 1887, the coal-bearing rocks of
Great Falls, Mont., were referred to the Kootanie by Professor
J. S. Newberry,3 who later discussed the flora more fully and
pointed out its close relationship with the flora of the Potomac.
The possible occurrence of beds of the same age in the Black
Hills, South Dakota, has been shown by Professor L. F. Ward*
on the evidence of cycads and a few other plants of Lower
Cretaceous aspect in beds that have formerly been referred to
the Dakota.

Before this time and soon after the Potomac formation
became known, Smith and Johnson’ had described the Tusca-
loosa formation in Alabama. It is now correlated with the
upper portion of the Potomac or the Raritan beds.

™Geol. Surv. of Canada, Rept. of Progress for 1872-3, pp. 32-65.

2Science, Vol. V, 1885, p. 31; Trans. Roy. Soc. Canada, Vol. III, 1885, sec. 4,
pp. 1-22; idem, Vol. X, 1892, sec. 4, pp. 79-93.

3School of Mines Quarterly, Vol. VIII, 1887, pp. 327-330; Am. Jour. Sci., 3d
ser., Vol. XLI, 1891, pp. 191-201.

4Jour. GEOL., Vol. II, 1894, pp. 250-266.
5 Bull. U. S. Geol. Surv., No. 43, 1887, p. 95.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 587

From this review it is seen that the Lower Cretaceous forma-
tions now known in the United States are the Comanche series
of the Texan region, the Shasta group (including Knoxville and
Horsetown beds) of the Pacific Coast, the Kootanie of Montana
and possibly of the Black Hills, the Potomac of the Atlantic
coastal plain, and the Tuscaloosa of the Gulf border. Only the
first two are marine formations. In our comparisons of these
formations it will not be necessary to enter into minute details
of stratigraphy and lithology, since the most general descrip-
tions will show that in most cases we have to deal with contrasts
rather than with resemblances. This is true not only when the
marine beds are compared with the non-marine, but also when
the two marine formations are compared with each other, or the
Potomac is compared with the Kootanie. In the descriptions
that follow, mainly summarized from the latest published
accounts, the principal characteristics of each formation are
given, beginning with the fresh-water beds. The statements
concerning the invertebrate faunas embody more of the results
of my own studies.

GEOLOGIC DESCRIPTION OF THE FORMATIONS.

The Potomac formation.— This term was originally applied by
McGee to certain non-marine beds in Maryland, the District of
Columbia, and Virginia, resting against the old crystalline rocks
of the Piedmont region, and unconformably overlain by marine
Upper Cretaceous deposits. The Potomac as thus defined is
composed of irregular deposits of variegated clays, sand, arkose,
pebbles, and bowlders, with local lenses of iron ore and lignitic
seams. The sand and arkose are sometimes indurated, but fre-
quently are unconsolidated deposits. In general, the arenaceous
deposits seem to predominate in the lower part of the series
and argillaceous beds in the upper, though no single stratum
retains the same lithologic character over any considerable
area. The estimates of thickness vary from 500 or 600 feet
(McGee) to 1175 feet (Ward). Professor Ward,’ who has

*See 15th Ann. Rept. U. S. Geol. Surv., pp. 313-397, and 16th idem, pp. 469-540.

588 TIMOTHY WILLIAM STANTON

studied the stratigraphy and the flora of the Potomac in great
detail, retains under that name all the strata originally included
in it, and also makes it comprise all the beds that have been
named the Raritan formation, extending from Maryland across
Delaware and New Jersey to the islands off the southern coast
of New England. That is, he makes it coextensive with Dr.
White’s? non-marine division of the Cretaceous of the Atlantic
border region which was believed to consist of two distinct
formations, separated by a time interval that marked the dis-
tinction between Lower and Upper Cretaceous. Though assign-
ing these beds all to a single formation Professor Ward recog-

’

nizes in it six distinct ‘‘series,’’ as follows:

(6. Albirupean [in part equivalent to Raritan |.
| 5. Iron Ore,
: 4. Aquia Creek,

Powsomumeye . Mount Vernon,

w

| 2. Rappahannock,
L 1. James River.

Each of these divisions, excepting No. 5, is, according to the
author cited, characterized by a distinct florula altogether consti-
tuting a flora of from 800 to 1000 species. Detailed discussions
and comparisons of this flora are contained in the articles above
referred to in the fifteenth and sixteenth annual reports of the
U.S. Geol. Survey. From these it appears that while the whole
formation is referred to the Lower Cretaceous the flora of the
lower beds, in which the earliest known dicotyledons appear, has
Jurassic affinities, and is related tothe Wealden flora. There is a
progressive change, the modern types predominating more and
more until in the uppermost beds (No. 6) the plants show a
marked affinity to the Upper Cretaceous Cenomanian flora. An
interesting comparison of the Potomac flora with the Lower Cre-
taceous flora of Portugal, shows that while they have but few
species in common the general characters of the two floras are
very similar, and as Professor Ward remarks, ‘‘the lower Creta-
ceous flora of Portugal is, botanically speaking, a very close repe-
tition of that of America.’ This fact is in interesting agreement

t Bull. U. S. Geol. Surv., No. 82, pp. 74-100.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 589

with other independent sources of evidence, for the Portuguese
plant beds are interstratified with strata carrying marine faunas
that are, as we shall see, closely related to the fauna of the Com-
anche series, and one of the lower horizons in the Comanche has
yielded fossil plants closely connected with the flora of the lower
Potomac.

Invertebrate fossils are remarkably scarce in the Potomac,
and the few that have been found do not afford any definite
evidence as to the age of the beds. The only mollusks known
from the lower horizons developed in Maryland and Virginia,
are a few internal casts apparently belonging to small simple
forms of Unio, whose only geological value is to show the fresh-
water origin of the beds. In New Jersey, besides some Unios
that probably came from a much later formation, five species of
mollusks have been reported from the Raritan formation.* They
have been referred to Astarte, Corbicula, Gnathodon, and
Ambonicardia (gen. nov.), but not one of them is well enough
preserved to show generic characters, and in invertebrate paleon-
tology, at least, age determinations, based on new species of
doubtful genera, are worthless.

Vertebrate fossils have been collected from the Lower Poto-
mac in a limited area between Washington and Baltimore. One
species based on a tooth, Astrodon Johnsoni, has been described
by Dr. Leidy, and Professor Marsh? has named five others:
Pleurocoelus nanus, P. altus, Priconodon crassus, Allosaurus medius,
and Coelurus medius. He states that associated with these there
are remains of crocodiles and_ tortoises, of Jurassic types,
some fishes and a few mollusks. Also that ‘‘The fossils here
described, and others from the same horizon seem to prove con-
clusively that the Potomac formation in its typical localities in
Maryland is of Jurassic age and lacustrine origin.’”” The genera
Allosaurus and Coelurus were originally described from the
Atlantosaurus beds (Jurassic) of the Rocky Mountain region,
and Pleurocoelus has since been found in the same beds repre-

*Monograph 9, U.S. Geol. Surv., pp. 22-28,

? Am. Jour. Sci., 3d. ser. Vol. XXXV, 1888, pp. 89-94.

590 TIMOTHY WILLIAM STANTON

sented by a Potomac species. According to Lydekker Pleuro-
coelus also occurs in the Wealden of England. In recent papers
Professor Marsh’ has attempted to establish the Jurassic age
of the whole Potomac formation in its broadest sense. He
correlates it by the relationship of the vertebrate faunas on the
one hand with the Atlantosaurus beds, and on the other with the
European Wealden, asserting that they are homotaxial equiva-
lents. Assuming that the Atlantosaurus beds are Jurassic, it
consequently follows, according to his reasoning, that the
Wealden and the Potomac are also Jurassic. But even admit-
ting that the vertebrate faunas are so closely related as to estab-
lish the equivalence of the deposits in these three widely
separated regions, the correlation can apply only to the beds in
which the fossils occur, and in the Potomac they have so far
been found only in the lower portion. Recent stratigraphic
studies by Professor W. B. Clark and Mr. Arthur Bibbins on the
Potomac in Maryland, have an important bearing on this ques-
tion. A preliminary statement of their results, including a new
classification of the deposits, was published? some months ago,
and a more detailed account has been issued since the present
paper was first written. Their most important results are sum-
marized as follows:

“Tt is the conclusion of the authors, founded upon a detailed
stratigraphic study of the Potomac group, that all the beds
which have afforded dicotyledonous types of plant life are
above those from which Professor Marsh has obtained vertebrate
remains, and moreover, that a marked unconformity exists
between the two series of deposits. ....

“The several formations into which the larger unit of the
Potomac group has been divided, are as follows:

tAm. Jour. Sci., 4th ser., Vol. II, 1896, pp. 295-298, 375-377, 433-447. See also
articles on the same subject by HOLLICK, WARD, HILL, and GILBERT, Science, Vols.
IV and V, 1896, 1897.

? Physical Features of Maryland; Maryland Geol. Surv., Vol. I, Pt. 3, pp. 56-59,
April 1897.

3JouR. GEOL., Vol. V, pp. 479-506, July-Aug. 1897.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 59!

Raritan re 8
Lower Cretaceous Patapsco * Potomac.
é Arundel - Group”
PY
Upper Jurassic (?) ee a

According to these authors all of the Potomac vertebrates
that have been recorded have come from the Arundel formation,
while practically the whole of the Potomac flora occurs in higher
horizons above the principal unconformity which separates the
Patapsco from the Arundel. All of Professor Ward’s plant-
bearing ‘‘series” below the Albirupean are believed to be local
subdivisions and variations of the Patapsco formation. The
underlying beds are doubtfully assigned to the Upper Jurassic
on the authority of Professor Marsh’s determination of the
affinities of the vertebrates. It has been shown, however, that
his comparisons are chiefly with the Wealden fauna, and if the
difficult stratigraphy of the Potomac has now been correctly
determined the evidence tends to prove the post-Wealden age of
the principal plant-bearing horizons.

There have long been differences of opinion as to the age of
the Wealden, and it may well be that it is partly Jurassic, but its
constantly close association with the Cretaceous, and the fact
that where it is present the lowest marine beds of the Neocomian
are always absent, are strong arguments for regarding it asa
non-marine facies of the Neocomian. If all the Wealden
deposits are transferred from the Cretaceous to the Jurassic
because the dinosaurs are closely related to those of the Jurassic,
then we know practically nothing of the land fauna of the Lower
Cretaceous, and no one can say whether the dinosaurs that must
have lived in early Cretaceous time, were very different from
those of the Jurassic or not. Professor Marsh’s statements may
be fairly interpreted to mean that the age of the Atlantosaurus
beds is dependent on that of the Wealden, and if the latter is
Cretaceous the former are also. There is nothing in the strati-
graphic relations of the Atlantosaurus beds that would prevent
their reference to the Lower Cretaceous, for they are every-
where immediately overlain by Upper Cretaceous strata.° How-

There is a possible exception to this in the Black Hills of South Dakota, where

592 TIMOTHY WILLIAM STANTON

ever these questions may be finally decided, it is evident that the
discussion as to the Potomac formation is not so much on its
correlation with deposits elsewhere as on the more general
question of the upper limits of the Jurassic.

The Tuscaloosa formation The beds known under this name
have their principal development in Alabama, extending thence
eastward into Georgia and westward into Mississippi. According
to Prof. E. A. Smith* the formation consists of ‘‘heavy bedded
purple and mottled and gray clays in the lower parts, alternating
with more distinctly stratified clays containing an abundance of
plant remains, chiefly in the form of leaf impressions. Above
these clayey beds are sands of various colors, white, yellow, gray,
pink, and purple, usually micaceous and strongly cross-bedded.
In many places irregular pockets of small angular chert pebbles
are interbedded with the sands, but these pebble beds make only
a very small proportion of the strata. In places also beds of
dark red and mottled clay occur in the upper part of the forma-
tion.” In the eastern part of the area it rests on ancient crystal-
line rocks while farther west it laps up on the Paleozoic sed-
iments. The overlying beds are of Upper Cretaceous age.

The thickness of the Tuscaloosa is estimated at 1000 feet.

Lithologically and stratigraphically the Tuscaloosa is seen to
correspond closely with the Potomac and the evidence of the
flora leads to the same correlation. Professor Smith? publishes
a list of 35 species of fossil plants determined by Professor Ward,
who compares them with the Amboy Clay (2. e. Uppermost Poto-
mac) flora. In later publications Professor Ward3 definitely
correlates the Tuscaloosa with the Amboy and Raritan clays,
suggesting that possibly one of the older horizons of the Poto-
mac may also be represented in Alabama. No animal remains
Protessor Ward obtained plants that he regards as Lower Cretaceous, and the Atlanto-
saurus fauna has also been found in this same region, but what relation the plant-beds

have to the vertebrate horizon, and whether the plants and vertebrates do not really
occur in the same bed has not been determined. ;

* Rep. on Geol. of the Coastal Plain of Ala., pp. 307-308, Montgomery, 1894.

2 [bid., p. 348.

315th Ann. Rept. U.S. Geol. Surv., pp. 337-338; 16th Ann. Rept., p. 470.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 593

have been reported from these southern beds. According to
Mr. N. H. Darton’ the Potomac deposits are practically contin-
uous along the whole Atlantic coastal plain until they connect
with the Tuscaloosa. It is evident that conditions of deposition
were remarkably uniform throughout this long coastal border
region during Potomac time but the earlier part of the epoch is
recorded by deposits now visible only in the middle portion of
the area. The northern and southern ends either did not receive
deposits until towards the close of the epoch or else the early
deposits were overlapped and concealed by the later beds.

The Kootanie formation.— A somewhat detailed description of
the typical area of the Kootanie is given by Dr. Geo. M. Dawson.?
It is found in the Rocky Mountains of Canada between latitudes
49° and 51°30’.
of over 7000 feet and consist chiefly of shales and sandstones of

The beds there havea total estimated thickness

very varied texture and appearance, with beds of coal. The
Canadian localities have yielded a flora3 of about 27 species
which show by identical and allied species a very close relation-
ship with the Potomac. No animal remains have been reported
excepting one imperfect specimen of a Goniobasis indicating
fresh waters, and a fragment of a belemnite which was very
probably derived from an older formation.

In the United States the Kootanie occurs at Great Falls, Mon-
tana, near which place a thick coal bed in the formation is mined.
The section has been described by Mr. W. H. Weed‘ who states
that the Kootanie ‘is a series of rapidly alternating sandstones
and clay shales with few and thin beds of impure limestone.
Individual beds are inconstant, the heavy ledges of heavy sand-
stone passing laterally into arenaceous clays and vice versa.”

The top of the formation is not clearly defined but the thick-
ness is evidently several hundred feet. About 38 species of fossil

* Bull. Geol., Soc. Am., Vol. VII, 1896, pp. 514-517.

?Rept. Geol. Surv. of Canada for 1885, Rept. B. A more general account in
Am. Jour. Sci., 3d ser., Vol. XX XVIII, pp. 120-127.

3Trans. Roy. Soc. Canada, Vol. III, 1885, Sec. 4, pp. 1-10. Idem, Vol. X, 1892,

SCA PO OS mee lGem- a VOlm Nl TSO2s SEG. Anise
4Two Montana coal fields. Bull. Geol. Soc. Am., Vol. III, 1892, pp. 301-323.

TIMOTHY WILLIAM STANTON

plants have been listed or described from the Kootanie of this
neighborhood by Professors Newberry*tand Fontaine.* Theseshow
a close connection with the not distant Canadian Kootanie, and
more than half of them (21 out of 38) have also been identified
from the Potomac. It is noteworthy, however, that no dico-
tyledons have been found in the Kootanie, thus indicating that
the higher horizons of the Potomac are possibly not represented
there. Invertebrates are represented in the Great Falls area only
by a few imperfect specimens of Unio. A higher bed which may
belong to a later formation has yielded undescribed species of
Neritina, Goniobasis, and Corbula (?).

It is evident that the Kootanie and Potomac were laid
down in distinct basins of fresh and brackish waters and that the
floras prove that they are in part homotaxial equivalents.

The Shasta group.— This general name was given by Gabb
and Whitney to all the Lower Cretaceous rocks of California.
Incisss DiC Ao Whites and Dr TG: i Becker. mamiedmino
subdivisions of the Shasta, the Knoxville and the Horsetown beds,
that have since been generally recognized. Detailed sections
have been described by Turner,‘ Diller5 and the present writer °
who has recently reviewed the geology of the Knoxville beds
and described their fauna.

The Shasta is a marine formation distributed along the western
side of the Sacramento valley and in the coast ranges of Califor-
nia, Oregon, and Washington. The lower divisions have been
recognized as far north as latitude 35°.

“Dark clay shales greatly predominate over all other kinds
of rocks in the Knoxville beds, but there is also considerable
sandstone, usually in thin beds. In some places the lower part
of the formation consists of alternations of shale and sandstone,

t Am. Jour. Sci., 3d ser., Vol. XLI, 1891, pp. 191-201.

2 Proc. U.S. Nat. Museum, Vol. XV, 1892, pp. 487-495.

3 Bull. U. S. Geol. Surv., Nos. 15 and Io.

4 Bull. Geol. Soc. Am., Vol. II, 1891, pp. 303-314.

5Am. Jour. Sci., 3d ser., Vol. XL, 1890, pp. 476-478. Bull. Geol. Soc. Am.,

Vol. IV, 1893, pp. 205-224. Idem, Vol. V, pp. 435-464.
6 Bull. U. S. Geol. Surv., No. 133, 1896.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 595

or calcareous material, in bands only a few inches thick. There
are also occasional thicker bands of sandstone, and sometimes
' massive conglomerates. The larger bodies of shale frequently
contain many calcareous concretions, and such concretions are
sometimes found even in the coarse conglomerates. More rarely
there are larger bodies of limestone, several feet in thickness,
but they do not form continuous beds of any great extent. The
conglomerates also appear to be local deposits of no great
length, though sometimes of very considerable thickness.” The
overlying Horsetown beds have essentially the same lithologic
character and are distinguished mainly by marked differences in
the fauna—especially by the absence of Aucella and the greater
abundance and variety of the ammonites. Where the base of
the Shasta has been observed it rests on metamorphic rocks of
undetermined age. It is conformably overlain by the upper
Cretaceous Chico formation which in its basal portion is proba-
bly as old as the Cenomanian.

The Lower Cretaceous has an enormous thickness at some
localities on the Pacific coast. A sectionon Elder Creek, Tehama
county, Cal., measured by Mr. Diller, showed about 20,000
feet of Knoxville and 6000 feet of Horsetown beds without any
evidence of duplication of strata. This thickness is exceptional,
though other localities in the same region show apparent thick-
messes of 12,000 to 15,000 feet:

Although the Shasta group is of marine origin it has yielded
a number of land plants from several different horizons ranging
from the upper third of the Knoxville to near the top of the
Horsetown beds. Professor Fontaine has recognized twenty-six
different forms among them. He says that ‘all have their
nearest relations in Lower Cretaceous forms, and there is no
plant that would indicate an age different from Lower Creta-
’ A large proportion of the species occur in the Potomac
and a feware found in the Kootanie and in the Comanche series,
none of which offers any other means of direct comparison with
the Shasta. Here, as in the Kootanie, no dicotyledons have
been found.

ceous.’

590 TIMOTHY WILLIAM STANTON

Injemiy jecent work on the Knoxville fauna the following

species are described :

Rhynchonella schucherti S.
R. whitneyi Gabb
Rhynchonella sp.
Terebratula sp.
Terebratula californica S.
Ostrea sp.

Anomia senescens S.
Spondylus fragilis S.
Lima multilineata S.
Pecten californicus Gabb?
Pecten sp.

Pecten complexicosta Gabb
Avicula whiteavesi S.
Aucella piochii Gabb

A. piochii var. ovata S.
A. crassicollis Keyserling
Inoceramus ovatus S.
Modiola major Gabb
Myoconcha americana S.
Pinna sp.

Arca textrina S.
Pectunculus ? ovatus S.
Nucula gabbi S.

Nucula storrsi S.

Leda glabra S.
Cardiniopsis unioides S.
Solemya occidentalis S.
Astarte corrugata S.
Astarte californica S.
Astarte trapezoidalis S.
Opis californica S.
Lucina ovalis S.

L. colusaensis S.

Cyprina occidentalis Whiteaves

Solecurtus ? dubius S.
Corbula? persulcata S.
Corbula filosa S.

To quote again from my previous paper: ‘‘When studying
the Knoxville fauna as a whole, either in the field or from aver-

Dentalium californicum S.
Helcion granulatus S.
Fissurella bipunctata S.
Pleurotomaria sp.

Turbo paskentaensis S.

T. wilburensis S.

T. trilineatus S.

T. colusaensis 5.

T. morganensis S.

T.? humerosus S.
Amberleya dilleri S.
Atresius liratus Gabb
Turritella sp.
Hypsipleura ? occidentalis S,
Hypsipleura gregaria S.
Cerithium paskentaensis S.
C. strigosum S.

Cerithium sp.

Aporrhais sp.

Phylloceras knoxvillense S.
Lytoceras batesi (Trask)
Desmoceras californicum S.
Desmoceras sp.
Olcostephanus mutabilis S.
O. trichotomus S.

Hoplites hyatti S.

H. storrsi S.

H. angulatus S.

H. crassiplicatus S.

H. dillenS.

Perisphinctes sp.
Diptychoceras ? sp.
Crioceras latus Gabb
Aptychus ? knoxvillensis S.
Belemnites impressus Gabb
Belemites tehamaensis S.
Belemites sp.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 597

age collections, one is impressed with the excessive preponder-
ance of the Aucelle, so far as number of individuals is
concerned. In many places they are so abundant that they
must have actually monopolized the sea bottom, crowding out
everything else.

‘Considering the fauna as an assemblage of species, the pro-
portion of brachiopoda, though there are so few, is somewhat
greater than in other American Cretaceous faunas. Among
the mollusca the variety of forms of Turbinide is noteworthy.
The proportion of ammonoids is also quite large, and there is
an unusual development of the genus Hoplites.”’

The Aucellz.do not pass above the Knoxville, or to speak
more accurately, the top of the Knoxville is drawn at the upper
limit of the Aucella beds. Several other Knoxville species, how-
ever, do pass up into the succeeding Horsetown fauna. This
fauna has not yet been revised and a considerable number of
undescribed species are known in recent collections, but the fol-
lowing lists, though incomplete, will give a correct idea of its
general character. In the lower part of the Horsetown ammon-
ites are locally very abundant, the genera Lytoceras and Phyl-
loceras being especially well represented in individuals. The
following species occur in this portion of the series:

Pentacrinus sp. Potamides diadema Gabb
Rhynchonella sp. Helicaulax ? bicarinata Gabb
Pecten operculiformis Gabb Actzon impressus Gabb
Plicatula variata Gabb Lytoceras batesi (Trask)
Avicula whiteavesi Stanton Phylloceras onoense Stanton
Inoceramus sp. Hoplites remondi (Gabb)
Nemodon vancouverensis (Meek) Olcostephanus traski (Gabb)
Trigonia equicostata Gabb Desmoceras hoffmanni (Gabb)
Trigonia leana Gabb ? Crioceras latus Gabb

Opis sp. Crioceras percostatus Gabb
Eriphyla sp. Ancyloceras remondi Gabb
Protocardia sp. Helicancyclus zquicostatus Gabb
Pleuromya papyracea Gabb Diptychoceras levis Gabb
Lunatia avellana Gabb Belemnites impressus Gabb

The few fossils that have been collected from the middle
portion of the Horsetown do not show any decided change in

598 TIMOTHY WILLIAM STANTON

the fauna until the extreme upper beds are reached, when a
more abundant fauna appears that shows a blending with the
succeeding Upper Cretaceous Chico fauna. These upper Horse-
town beds have yielded the following species :

Rhynchonella sp. © Mactra sp.

Exogyra parasitica Gabb Pleuromya papyracea Gabb
Pecten operculiformis Gabb Panopza concentrica Gabb
Mytilus quadratus Gabb Lunatia avellana Gabb

Mytilus cf. lanceolatus Sowerby Liocium punctatum Gabb
Cucullzea truncata Gabb Acteonina californica Gabb
Nemodon vancouverensis (Meek) Ringicula varia Gabb

Leda translucida Gabb Desmoceras hoffmanni (Gabb)
Trigonia equicostata Gabb Desmoceras cf. beudanti (Brongniart)
Trigonia leana Gabb Haploceras brewer (Gabb)
Meekia sella Gabb Lytoceras sacya Forbes
Meekia navis Gabb Schloenbachia inflata (Sowerby)
Meekia radiata Gabb Acanthoceras cf. mammillare
Chione varians Gabb (Schloth.)

Tellina matthewsonii Gabb Belemnites sp.

After weighing the available paleontologic evidence and
making all practicable comparisons with foreign Mesozoic fossils
the conclusion was reached that the whole of the Knoxville is
referable to the Neocomian and that the Horsetown includes all
the rest of the Lower Cretaceous and possibly extends up into
the Upper Cretaceous.

The abundance of Aucelle gives the Knoxville fauna a decided
boreal appearance, for the distribution of that genus has been
considered essentially circumpolar. Some of the ammonitic
types also point in the same direction, but the genera Lytoceras
and Phylloceras are also represented, and these are the genera
that Neumayr considered especially characteristic of the southern
or tropical zone. With the disappearance of Aucella the fauna
of the Horsetown becomes almost purely southern in type, so
far as the ammonites are concerned, as Professor J. P. Smith*
has stated; but this change can hardly be attributed to a change
in climate, for it will be remembered that Aucella beds occur as

tMesozoic Changes in the Faunal Geography of California, JouR. GEOL., Vol.
III, 1895, pp. 381-382.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 599

far south as the Himalayas in India and almost to the tropics in
Mexico. Besides, the fossil plants of both divisions of the Shasta,
as well as those of the more northern Kootanie, indicate at least
a warm temperate climate.t The facts seem to support Dr. Koss-
mat’s? opinion that Neumayr exaggerated the influence of cli-
mate on the distribution of ammonites [and other Mesozoic
invertebrates as well], and that the climatic influence was of
little importance when compared with geographic relations, the
presence or absence of opportunities for free communica-
tion, etc. Neumayr3 himself referred the California Creta-
ceous to his Indo-Pacific region, and spoke of the persistent
conservative character of the Mesozoic faunas of that region.
The earliest Cretaceous deposits are apparently not preserved on
the Asiatic side of the Pacific, but beginning with the Upper
Cretaceous beds, usually classed as Cenomanian, on about the
horizon of the uppermost Horsetown beds, very closely related
faunas are widely distributed around the borders of the great
Pacific basin. They occur in southern India, Japan, Saghalin,
Queen Charlotte Islands, Vancouver, and, according to Stein-
mann,+ on the west coast of Chile. While Lower Cretaceous
deposits are not so widespread in that region, the character and
distribution of their fauna down the west coast of North America
seem to indicate that the Pacific was then the home of a uni-
form fauna, and that it was directly connected with the boreal
sea that covered Russia and Siberia, but was not in communica-
tion with the Atlantic. This subject can be discussed more
satisfactorily after reviewing the Cretaceous of the Texas region.

The Comanche series.~-In area and in faunas the greatest
development of the Lower Cretaceous in the United States is the
Comanche series of the Texan region. Its outcrops extend from
western Arkansas through southern Indian Territory to Denison
and Preston, thence southward through Fort Worth, Austin, and

™S1r J. W. Dawson, Trans. Roy. Soc. Canada, Vol. X, 1892, Sec. 4, pp. 81-82.

2 Jahrb. der k. k. geol. Reichsanstalt, 1894, Bd. 44, p. 476.

3Erdgeschichte, Bd. 2, p. 391, 1883.

4 Neues Jahrb. f. Mineral., Geol. und Palaont., Beilage Bd. 10, 1895, pp. 1-118.

600 TIMOTHY WILLIAM STANTON

San Antonio to the Rio Grande at Del Rio, covering large areas
west of that line. It is known to underlie a large part of
Mexico, extending as far west as Arivechi in Sonora. Small
outlying areas occur in southern Arizona, at El] Paso, Texas,
in eastern New Mexico, in Oklahoma, and in southern Kansas.
The stratigraphic details have been published mainly by Messrs.
Ry Ue Bi fs AN enae, 185 1, IDimanole, We Je. Conamamins, 10, \\) .
Vaughan, and C. S. Prosser.

The main features of Mr. Hill’s classification of the deposits
are as follows:

( Shoal Creek limestone,

’ Washita | Denison beds,

1 Fort Worth limestone,
| Preston beds.

| Caprina (Edwards) limestone,
Comanche series ~ Fredericksburg + Comanche Peak limestone,
| Walnut clays.

io Paluxy sands,
| Trinity Glen Rose limestone and clays,
: | Trinity sands.

This list gives the principal recognized subdivisions and ind1-
cates the lithologic character of the section in central Texas.
Calcareous sediments of varying texture and composition largely
predominate over all other kinds, thus contrasting strongly with
the Shasta deposits. Considerable beds of sand are locally
developed in the lower or Trinity division, and in the middle of
the Washita clays and sandy layers usually predominate, but as
a rule much more than) halt of the total thickness or sthe
Comanche series consists of calcareous beds. Near the borders
of the Comanche sea the limestones decrease in relative thick-
ness or disappear entirely. At El Paso they form but a small
proportion of the section, and in the Tucumcari region of New
Mexico and in southern Kansas the rocks are all sandstones and
clay shales. In the latter region the total thickness is only
about 200 feet, and apparently the Washita division is the only
one represented. In central Texas the entire series has a thick-
ness of about 1500 feet, which increases southwestward, until

LOWER CRETACEOUS FORMATIONS AND FAUNAS 601

in northern Chihuahua it reaches 4000 feet, as estimated by Dr.
C. A. White,’ and still farther south very much greater thick-
nesses have been reported. Lithologically the Comanche series
as a whole contrasts strongly with the Cretaceous rocks of all
other parts of the United States, and indeed of North America,
excepting Mexico, which is directly connected with the Texan
area. Judging from the descriptions, lithologically similar Cre-
taceous rocks are developed to some extent in the northern part
of South America and in southern Europe. We must go to these
regions also, and especially to Portugal and Spain, as Mr. Hill
has pointed out, to find closely related faunas.

Fossil plants have been obtained from two horizons, one in
the Glen Rose beds of the Trinity division, about 250 feet above
the base of the series, and the other in the so-called Cheyenne
sandstone, at the base of the Cretaceous section in southern
Kansas, but apparently within the Washita division. The
plants from the lower horizon, which are directly associated with
an abundant marine fauna, have been described by Professor
Fontaine. He recognized twenty-three distinct forms, consist-
ing mainly of conifers and cycads, with a fern, an Equisetum,
and a few forms of uncertain affinities. Of these seven are rep-
resented by identical and six by similar species in the Potomac,
four occur in the Wealden of Europe, two in the Urgonian, with
an additional one represented by a similar form, and six are
peculiar to the Glen Rose. In discussing the age and affinities
of these plants Professor Fontaine says: ‘‘The plants found at
Glen Rose show, so far as can be judged from so imperfect a
collection, that the Trinity flora finds its closest resemblance in
the older portion of the lower Potomac. There is, however, this
important difference: no trace of angiosperms, even the most
archaic, has been found in the Texan region, We have only the
four elements of the typical Jurassic flora. This, then, makes the
Trinity flora somewhat older than that of the oldest Potomac.
The absence of angiosperms and the presence of the forms that

* Am. Jour. Sci., 3d ser., Vol. XX XVIII, 1889, pp. 440-445.

?Proc. U.S. Nat. Museum, Vol. XVI, 1893, pp. 261-282.

602 TIMOTHY WILLIAM STANTON

are found indicate decidedly that the Trinity flora is not younger
than the earliest stage of the Cretaceous. The number of plants
found to be identical with certain of those of the oldest Potomac
shows that there is little difference in the age of the two formations.
The plant-bearing portion of the Trinity is somewhat older thanthe
basal Potomac strata, but the difference in age cannot be great.”’

In this reasoning it seems to me that too much stress is laid
on negative evidence, the absence of angiosperms. The present
habits and distribution of plants do not warrant the assumption
that a small collection containing only twenty-three species from
a very limited area would necessarily include all the important
types of plants living at the time they were entombed. The
still more striking incompleteness of the Lower Cretaceous
faunas will be discussed beyond. It will be remembered that the
Kootanie flora and the plants from the Shasta, which were also
compared with the Potomac flora, likewise showed the absence of
dicotyledons and this was true even in the Horsetown beds
which are known from their fauna and stratigraphic position to
be far above the base of the Lower Cretaceous.

Among the plants from the Washita horizon in southern
Kansas, Dr. Knowlton" has recognized seven species of which
five are dicotyledons and two are conifers. The species identi-
fied had before been found only in the Dakota group ina flora
usually assigned to the Cenomanian. It has been shown by
Cragin,” however, that a part of the beds referred to the Dakota
probably belongs to the Comanche series. At all events it is
certain that the upper part of the Comanche approaches the
Upper Cretaceous in character and it probably is not far from
the horizon of the uppermost Potomac beds.

The vertebrates obtained from the Comanche series are few
and mostly fragmentary. The descriptions and determinations
of Williston,3 Cragin,¢ and Cope’ show the presence of fishes,

*In a paper by Mr. HIL1, Am. Jour. Sci. 3d. ser. Vol. L, 1895, pp. 212-214.

?Am. Geologist, Vol. XVI, 1895, pp. 162-165.

3 Kansas Uni. Quarterly, Vol. III, 1894, pp. 1-4.

4 Colorado College Studies, Vol. V, 1895, pp. 69-73.
5Jour. Acad. Nat. Sci. Phila., Vol. IX, 1895, pp. 443-447.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 603

turtles, crocodiles, and plesiosaurs but they have not furnished
any very definite evidence as to the age of the beds. One of the
fishes (described by Cope) came from the Glen Rose beds and
another from an unknown locality in Texas. All the other
vertebrates mentioned are from higher beds near Camp Supply,
Oklahoma, and in southern Kansas. Fragmentary bones that
are supposed to be dinosaurs but have not been definitely identi-
fied have been collected in the Trinity sands by Mr. Hill.

The invertebrate fossils are,very numerous throughout almost
all of the series above the basal Trinity sands, and constitute
several distinct subfaunas though all are connected by species
that pass from one zone to another and a few species range
through a large part of the series. The species have been mostly
described in various books and papers by Roemer, Giebel, Mar-
cou, Shumard, Gabb, White, Hill, and Cragin. The revision of
the invertebrate species with the description of new forms con-
tained in recent collections on which I am at present engaged
has not progressed far enough to enable me to give complete
lists of the fossils of each zone but the general features of the
fauna can be profitably discussed and some interesting compari-
sons can be made.

Mr. Hill’s* reviews of the subfaunas of the Trinity division
and of the Caprina limestone in the Fredericksburg division
afford a basis for comparing these horizons with other Creta-
ceous beds. The list given for the Trinity (Glen Rose) includes
about forty invertebrate species and this number will be con-
siderably increased by the study of recent collections. The fol-
lowing characteristic forms, mostly from the same horizon as
the Glen Rose plants, are the most important for our present
purpose :

Ostrea franklini Coquand Requienia cf. texana Roemer
Trigonia stolleyi Hill Monopleura cf. marcida White
Trigonia crenulata (Lam.) Roemer Monopleura cf. pinguiscula White
Trigonia lerchi (Hill) Cyprina sp.

Trigonia n. sp. Natica (Lunatia) pedernalis Roemer

«Proc. Biol. Soc. Washington, Vol. VIII, 1893, pp. 9-40, 97-108.

604 TIMOTHY WILLIAM STANTON

Tylostoma sp. Glauconia cf. picteti Coquand

Glauconia branneri (Hill) Nerinea sp.

Glauconia cf. helvetica (Pictet and Neumayria? ? walcotti Hill
Renevier) Stoliczkaia justinae (Hill)

Excepting the ammonites and the last two species of Tri-
gonia these forms are all very abundant in certain layers and
give character to the fauna. The Ostrea is a simple form of
little diagnostic value mentioned merely on account of its abun-
dance. The Trigonias represent three groups, two of which,
scabre and quadrate, are characteristic of the Cretaceous and
the other, glabre, occurs in both Jura and Lower Cretaceous.
Requienia and Monopleura are not known outside of the Creta-
ceous and are found in the Urgonian and higher horizons of
Portugal and other southern European countries. Watica pied-
ernalis is very like NV. stmillinus Choffat of the Urgonian of Portu-
gal, and Choffat speaks of the great abundance of large Naticas
in that horizon, though similar forms also occur in the Valanginian
(Lower Neocomian) of the same region. The species of Glau-
conia are all represented by very similar southern European
forms ranging from the Urgonian to the Aptian and perhaps
higher. The two species of ammonites are not well enough
known to be compared satisfactorily but their nearest relatives
apparently are Lower Cretaceous species.

Several other forms have representative species in southern
Europe but when the comparisons are all made the final result is
not a definite correlation of the lowest fossiliferous beds of the
Trinity with any particular horizon of the Lower Cretaceous,
though the evidence is clear that it cannot be earlier than the
Lower Cretaceous and that it probably is not the base of the
Cretaceous.

*For stratigraphy and related species mentioned in this discussion see, CHOFFAT
Recueil de Monog. Stratig. sur le Systéme Crétacique du Portugal, Lisbonne, 1885
Recueil de Monog. paléont., etc., 1886.

PICTET et RENEVIER. Fossiles du Terrain Aptien de la Perte du Rhone.

PICTET et CAMPICHE. Fossiles du Terrain Crétacé des environs de Sainte Croix

Der LorIoL et DE LORIERE. Fossilés du Neocomien superieur de Utrillas.

CoQuaND, Monographie paléontologique de l’etage Aptien de l’Espagne.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 605

In the lower part of the Fredericksburg division the Naticas
and Tylostomas, in part identical with those of the Trinity con-
tinue to play an important part. Here we find the first beds of
Gryphaea belonging to the series of species that have often been
grouped under the single name Gryphaea pitchert Morton, but
which are now separated into several species. These Gryphaeas
occur in immense numbers at intervals to the top of the Co-
manche. Other ostreidae such as Exogyra and Alectryonia have
a great development of individuals representing several species.
Echinoids, belonging to the genera Enallaster, Hemiaster,
Epiaster, Holaster, Holectypus Pseudodiadema, Cidaris, and a
few others are also numerous and continue in greater or less
abundance in the calcareous beds to top of the series. Among
other common forms are Cyprimeria, with difficulty distinguish-
able from Upper Cretaceous species, several species of Nerinea,
Aporrhaidae, etc. Three important species of ammonites,
Engonoceras piedernalis (von Buch), Schloenbachia acutocarinata
(Shumard) and S. “rinitensis (Gabb) also occur.

The Caprina limestone constituting the upper part of the
Fredericksburg divison has an interesting and remarkable fauna
consisting largely of Requienia, Monopleura, Ichthyosarcolites
and other Chamidae, with Radiolites or Spheerulites, Nerinea,
many other gastropods, corals, etc. The general assemblage
of forms is very much like that in the ‘“Schrattenkalk” or
‘“Caprotina limestone” of the Urgonian and the similarity
extends to specific forms in many cases. There is aiso a more
superficial resemblance to the Upper Cretaceous ‘ Hippurite”’
limestone and it was partly this resemblance that caused Roemer
and Heilprin* to refer the Comanche series to the Upper Creta-
ceous. While it would perhaps not be justifiable to call the
Caprina limestone Urgonian (as defined by Choffat) or to say
that they are exact homotaxial equivalents yet such a statement
could not be very far from the truth. The two faunas resemble
each other in so many particulars that there must have been free
communication between the two areas and the conditions of

*Proc. Acad. Nat. Sci. Phila., 1890, pp. 445-4609.

606 TIMOTHY WILLIAM STANTON

marine life must have been very nearly the same in both but as
we do not know where the faunas originated nor the direction
and rate of migration we can not determine the exact time
relations of the deposits.

In the Washita division many of the elements of the Freder-
icksburg fauna continue either unchanged or but slightly modi-
fied. Among identical species that occur in the lower beds of
the Washita Exogyra texana, Turritella seriatim-granulata and
Schloenbachta acuto-carinata may be mentioned. The Engonoceras
group" of ammonites also reappears in the upper part of the
division. Ammonoids are more abundant in the lower Washita
(Preston and Forth Worth beds) than in any other part of the
Comanche series, though only a few types are represented.
Besides those already mentioned, the large Pachydiscus bra-
goensis (Shumard) and Hamites fremonti Marcou are abundant,
and there is a large development of the genus Schloenbachia,
mostly of the type S. fata (Sowerby). These forms together
with the large Turrilites brazoensis Roemer, if occurring in Europe
would probably be taken to indicate either uppermost Gault or
lowest Cenomanian. A large development of littoral forms in the
Denison beds of northern Texas, in the Tucumcari region of
New Mexico, and in southern Kansas also gives the faunaa
rather modern aspect. But its close relationship with the fauna
of the underlying Fredericksburg division and the fact that the
next succeeding fauna, that of the Timber Creek beds, contains
species of Acanthoceras and other types resembling those that
are characteristic of the Cenomanian in Europe tend to place it
lower in the Cretaceous system. The uppermost beds of the
Washita may possibly be as late as the Cenomanian, but the
lower beds in which Schloenbachia is so abundant can hardly
be more recent than the Gault. However this point may be
decided, the most natural major plane of division in the Texan

*This group including Ammonites piedernalis van Buch, frequently spoken of as
“Cretaceous Ceratites,” or as “ Buchiceras,” in the broad sense in which it was origi-

nally defined, is considered characteristic of the southern European or Mediterranean
Cretaceous.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 607

Cretaceous is at the top of the Comanche series, and this plane
seems to coincide very closely with the top of the Potomac and
the top of the Shasta.

It has already been mentioned that the Cretaceous of part of
the west coast of South America has some resemblance to the
Comanche series, but little is published about the stratigraphy,
and in describing the fossils few attempts have been made to
indicate the different horizons, so that it is now impossible to
make close comparisons. In Peru Schloenbachia acuto-carinata,
and several large Naticas and Tylostomas, occur with a few
other forms related to Comanche species. Similarly in Colum-
bia Ptychomya buchiana (Karsten), Exogyra boussingaulti d’Orb.
and several others have representatives in the Comanche. It
has been assumed by some authors that these forms lived in the
Pacific basin, and that they prove that the Pacific and Atlantic
were connected during Lower Cretaceous time.

By independent comparisons with European Cretaceous
faunas— principally northern European in one case and southern
or Mediterranean in the other—aided by stratigraphic relation
with overlying beds and by the evidence of the fossil plants we
have reached the conclusion that the Shasta group and the
Comanche series were essentially contemporaneous deposits.
And yet their faunas are almost totally distinct. This separate-
ness of the two faunas has frequently been mentioned by Dr.
White? and the present writer,” but the real character of the dif-
ferences has not been clearly Stated.« simemuiherences are, not
dependent on fine discrimination of closely related species. On
the contrary, whole genera and in some cases much higher
groups that are abundant and characteristic in one area are
entirely absent in the other. The following table will exhibit
some of the more striking contrasts :

tBull. U. S. Geol. Surv., No. 15, 1885, pp. 30-31; zdzd., No. 82, 1891, pp.
180-108.

2Bull. Geol. Soc. Am., Vol. 1V, 1893, p. 254; JouR. GEOL, Vol. III, 1895, pp.

858-861; Bull. U. S. Geol. Sury., No. 133, 1896, pp. 27, 31; DILLER and STANTON;
Bull. Geo. Soc. Am., Vol. V, 1894, p. 462.

608 TIMOTHY WILLIAM STANTON

Comanche,
Echinoids.......... Very abundant in several
horizons
Terebratula ....... Abundant in two beds
Rhynchonella...... Absent
OSTEICEDS Goo 040006 Immensely abundant and

represented by Ostrea,
Gryphaea, Exogyra, and

Alectryonia
MGM: co cococane Absent
Pirigomiayyeere tcl Common
IRWGLISS Gooncddc0c Abundant in Caprina Limest.
Chamide ......... Abundant in Caprina Limest.
Cyjomlineay ococ0b 0000 Very abundant
Protocardia ....... Large species abundant
Cyprimeria........ Abundant
Naticidzenme joc Large species abundant
Glauconia......... Abundant
eiurnitellayeyoceren-rert Abundant
INGMINEEs 6566000000 Abundant
Acteonella........ Locally abundant
Wy LO CET ASH ecier-ielcl ar: Absent
Phylloceras ....... Absent
lnloypobties coco bancée Rare
Ancyloceras....... Absent
Criocerasyecce ec Absent
JElaNaaitis cooo oo0G00 Abundant in one bed
Pachydiscus....... Abundant in one bed

Schloenbachia..... Abundant in Fredericksburg
and Washita divisions.
Several species
Engonoceras and
related Ammon-

ALES Pe rereexetaycverersyalt Common «
Auriitesimeroeerery Locally abundant
Belemmnitesee-e sce Absent

Shasta.

Presence barely indicated at
one locality in the Knox-
ville

Rarely represented

Locally abundant

Very scarce. A small Ostrea
in the Knoxville and
Exogyra at top of Horse-
town

Immensely abundant in the
Knoxville

Common, species not closely
related

Absent

Absent

Rare

One very small species of
distinct type

Absent

One or two small forms com-
mon

Absent

Very rare

Occurrence doubtful

Rare

Abundant

Abundant

Common

Common

Common

Absent

Absent

One species. Rare at top of
Horsetown

Absent
Absent
Common

The comparisons cquld be carried further, showing many other

genera that are found in only one of the areas, and that those

occurring in both are not represented by closely related species.

The two faunas are complements of each other, and both

must be taken together to make up a really representative Lower

Cretaceous fauna.

Their differences agree in a general way

with those that exist between the northern and southern

LOWER CRETACEOUS FORMATIONS AND FAUNAS 609

European Cretaceous, but there are some variations, such as the
occurrence of Lytoceras and Phylloceras with boreal forms in
the Shasta and their absence from the southern Comanche where
they belong.

As to the causes of the sharp contrasts between the Creta-
ceous faunas of the Texan region and the Pacific Coast, reasons
based on the distribution of the fossil plants and on the geo-
graphic relations of the deposits have already been given for
denying any considerable influence to climate, that is, difference
in temperature. Dr. White has argued for the existence of a
long, narrow, continental land barrier between the two areas of
deposition, and that is doubtless the only single cause that seems
at all adequate to explain the facts. But how far south the barrier
extended and whether its position was constant we do not know.
It is known that the Comanche fauna at one time extended
almost to the present Pacific Coast in northern Sonora, and there
is evidence that the Pacific fauna may have extended as far east
as Catorce in San Luis Potosi, but whether the two seas were
really connected or what their exact relations were we can only
hope to learn when the details of Mexican geology are fully
studied. Besides the existence of a barrier, the depth and clear-
ness of the sea and the character of the bottom also probably
had considerable influence. These conditions would at least
explain the abundance of echinoids in one case and their
absence in the other. The Shasta beds give every evidence of
rapid deposition near shore in shallow waters, with usually a
muddy bottom, while a large part of the Comanche series was
laid down in deeper waters, or at least little influenced by clastic
deposits derived directly from the land. One other factor has
suggested itself, though it is probably not of much weight, and
that is that the gregarious mollusks, like Aucella and the
Ostreidz, actually monopolized the sea bottom where either
became well established, so that there was not room for both in
the same area.

The study of these two incomplete faunas should emphasize
the danger in depending on the statistical method in correlating

610 TIMOTHY WILLIAM STANTON

formations— the method in which each specific name is treated
as a unit and the relative affinities of different deposits or local-
ities are determined automatically by counting the number of
common species. Here there are two great series of beds, each
with a fairly large fauna, and not very far separated geographic-
ally, and yet if directly compared they show no identical and
very few related species. Again, these conditions are sugges-
tive when considering a sudden complete change in successive
faunas, such as is often seen. If the barrier between the
Comanche and Shasta seas had been suddenly removed and the
succeeding conditions had been favorable for the continuation
of only one of the faunas, we would have had in one of the areas
such a complete and sudden change in faunas in two successive
beds that a long time interval might have been erroneously
invoked to explain it.

BIBLIOGRAPHY.
I. PAPERS RELATING TO LOWER CRETACEOUS OF THE UNITED STATES.

1823 Say, Thomas. Notes on fossils. Account of an expedition from Pitts-
burg to the Rocky Mountains, by Maj. Stephen H. Long, Vol. II, pp.
410, 411. Philadelphia.

1834 Morton, S. G. Synopsis of the organic remains of the Cretaceous
Group of the United States. Philadelphia.

1840 Rogers, Henry D. Description of the geology of the state of New
Jersey. Philadelphia.

18417 Booth, J.C. Memoir of the Geological Survey of Delaware, including
the application of the geological observations to agriculture, pp. 38-
43. Dover.

Rogers, W. B. Report of progress of Geological Survey of Virginia
for 1840. Richmond. Reprinted in Geology of the Virginias, pp.
437-449, 1884.

1842 Rogers, W. B. Report of progress of Geological Survey of Virginia
for 1841. Richmond. Reprinted in Geology of the Virginias, p.
542, 1884.

1846 Roemer, F. A sketch of the geology of Texas. Am. Jour. Sci., 2d
ser., Vol. II, pp. 358-365.

1848 Buch, L. von. Ueber Ceratiten. Abhandl. Akad. der Wissenschaften
fiir 1848, pp. I-30, pls. 1-6. Berlin.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 611

Roemer, F. Contributions to the geology of Texas. Am. Jour. Sci.,
2d ser., Vol. VI, pp. 21-28.

1849 Roemer, F. Texas. Mit besonderer Riicksicht auf deutsche Auswan-
derung. Bonn.

1852 Roemer, F. Die Kreidebildungen von Texas und ihre organischen
Einschliisse, mit einem die Beschreibung von Versteinerungen aus
paladozoischen und tertidren Schichten enthaltenden Anhange, und
mit 11 von C. Hohe nach der Natur auf Stein gezeichneten Tafeln.
100 pp. Bonn.

1853 Conrad, T. A. Descriptions of new fossil shells of the United States.
Jour. Acad. Nat. Sci., Phila., 2d ser., Vol. II, Part III, pp. 273-276,
pl. 24. Philadelphia.

Giebel. C. G. Beitrag zur Paldontologie des texanischen Kreidege-
birges. Jahresbericht des Naturwissenschaftlichen Vereines in
Halle. Berlin.

Marcou, Jules. Secondary rocks. Geol. Map. U. S. and British
provinces of N. A., pp. 39-47, pls. 6, 7. Boston.

Shumard, B. F_ Description of the species of Carboniferous and Cre-
taceous fossils collected. Expl. Red River of Louisiana, 1852. R.
B. Marcy. App. E., pp. 199-211, pls. 1-4. Washington. Another
edition, 1854, pp. 173-185.

Shumard, Geo. G. Remarks upon the general geology of the country
passed over by the exploring expedition to the sources of Red River.
Expl. Red River of Louisiana in 1852, pp. 179-195. Washington.
Another edition, 1854, pp. 156-172.

1855 Marcou, Jules. Résumé of a geological reconnoissance extending from
Napoleon, at the junction of the Arkansas with the Mississippi, to the
Pueblo de los Angeles, in California. Rept. Expl. fora railroad
route near the 35th parallel of lat. from the Mississippi River to the
Pacific Ocean. By Lieut. A. W. Whipple, Vol. IV, pp. 40-48, 8vo,
Washington. Reprinted in 4to Rept., Vol. III, Part IV, pp. 165-175.
Washington, 1856.

Marcou, Jules. Résumé explicatif d’une carte geologique des Etats-
Unis et des provinces anglaises de l’Amerique du Nord, avec un
profil geologique allant de la vallee du Mississippi aux cotés du
Pacifique et une planche de fossiles. Bull. Soc. Geol., France, 2d
ser., Vol. XII, pp. 813-936, pl. 21. Paris.

Marcou, Jules. Notes géologiques sur le pays compris entre Preston,
sur le riviére Rouge, et el Paso, sur rio Grande. Bull. Soc. Géol.,
France, 2d ser., Vol. XII, pp. 808-813.

1856 Blake, W.P. Report of the geology of the route near the 32d parallel.
Expl. and surveys for railroad route from the Mississippi River to

| the Pacific Ocean, Vol. II, Part IV.

612 TIMOTHY WILLIAM STANTON

Conrad, T. A. Descriptions of one Tertiary and eight new Cretaceous
fossils from Texas, in the collection of Major Emory. Proc. Acad.
Nat. Sci., Phila., Vol. VII, pp. 268-269. Philadelphia.

Marcou, Jules. Résumé and field notes. Rept. Expl. for railroad
route from Mississippi River to Pacific Ocean, Vol. III, Part IV, pp.
121-164. Washington.

1857 Conrad, T. A. Descriptions of Cretaceous and Tertiary fossils. Rept.
U. S. and Mex. Bound. Surv., Vol. I, Part II, pp. 141-143, 147-174,
pls. 2-21. Washington.

Hall, James, Geology and Paleontology of the Boundary. Rept. U,
S. and Mex. Bound. Survey, Vol. I, Part II, pp. 103-140. Wash-
ington.

Hall, James. Observations upon the Cretaceous strata of the United
States with reference to the relative position of fossils collected by
the Boundary Commission. Am. Jour. Sci., 2d ser., Vol. XXIV, pp.
72-86.

1858 Marcou, Jules. Geology of North America, with two reports on the
prairies of Arkansas and Texas, the Rocky Mountains of New
Mexico, and the Sierra Nevada of California, 4to, pp. 144, with 7
plates of fossils. Zurich.

1860 Gabb, W. M. Descriptions of new species of American Tertiary and
Cretaceous fossils. Jour. Acad. Nat. Sci., Phila., 2d ser., Vol. IV,
Part IV, pp. 375-406, pls. 47-49. Philadelphia.

Owen, D. D. Cretaceous fossils from Arkansas. Second Rept. Geol.
Reconnoissance of Arkansas. Philadelphia.

Shumard, B. F. Observations upon the Cretaceous strata of Texas.
Trans. St. Louis Acad. Sci., Vol. I, pp. 582-590.

Shumard, B. F. Descriptions of new Cretaceous fossils from Texas.
Trans. St. Louis Acad. Sci., Vol. I, pp. 590-610. St. Louis.

Tyson, Philip T. First Rept. State Agri. Chemist to the House of
Delegates of Maryland. Annapolis.

1861 Marcou Jules. Notes on the Cretaceous and Carboniferous Rocks of
Texas. Proc. Boston Soc. Nat. Hist., Vol. VIII, pp. 86-97. Boston.

1862 Shumard, B. F. Section of the Cretaceous strata in Texas. Proc.
Boston Soc. Nat. Hist., Vol. VIII, p. 89.

Shumard, B. F. Descriptions of new Cretaceous fossils from Texas.
Proc. Boston Soc. Nat. Hist., Vol. VIII, pp. 188-205. Boston.

Tyson, Philip T. Second Rept. State Agri. Chemist to the House of
Delegates of Maryland. Annapolis.

1864 Gabb, W. M. _ Description of the Cretaceous fossils of California.
Geol. Surv. Cal., J.D. Whitney, State Geologist, Vol. I, Palzeontology,
sec. 4, pp. 55-243, pls. 9-32. Philadelphia.

1868 Cook, Geo. H. Geology of New Jersey. Newark.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 613

1869 Coquand, H. Monographie du genre Ostrea. Terrain crétacé. 215

pp. Marseilles.

Gabb, W. M. Palzontology of California. Geol. Surv. Cal., J. D
Whitney, State Geologist, Vol. II, Paleontology, pp. 299, pls. 36
Philadelphia.

Kimball, James P. Notes on the geology of western Texas and of
Chihuahua, Mexico. Am. Jour. Sci., 2d ser., Vol. XLVIII, pp. 378-
388.

1875 Credner,G. R. Ceratites fastigatus und Salenia texana. Zeitsch. fiir

die Ges. Naturw. Neue Folge, Band XII, pp. 105-116, Taf. 5. Berlin.
Rogers, W. B. On the gravel and cobblestone deposits of Virginia
and the Middle States. Proc. Boston Soc. Nat. Hist., Vol. XVIII,
pp. lo1-1o6. Boston. Reprinted in Geology of the Virginias, pp.

709-713.

1876 Meek, F. B. Descriptions of the Cretaceous fossils collected on the

San Juan exploring expedition under Capt. J. N. Macomb, U. S.
Engineers. Rep. Expl. Exped., Santa Fé, New Mexico, to junction
Grand and Green Rivers, 1859, pp. 119-133, pls. 1-3. Washington.

1879 Fontaine, William M. Notes on the Mesozoic strata of Virginia. Am

Jour. Sci., III, Vol. XVII, pp: 25-39, 151-157, 229-239.

White, C. A. Contributions to Invertebrate Paleontology, No. 1. Cre-
taceous fossils of the western states and territories. Eleventh Ann.
Rep. U.S. Geol. and Geogr. Surv. Terr. (Hayden), for 1877, pp. 273—
319, pls. I-10. Washington.

1880 White, C. A. Contributions to Invertebrate Paleontology, No. 2. Cre-

taceous fossils of the western states and territories. Twelfth Ann.
Rept. U. S. Geol. and Geogr. Sur., Terr. (Hayden), for 1878, Part I,
pp. 5-39, pls. 11-18. Washington.

White, C. A. Descriptions of new Cretaceous Invertebrate fossils from
Kansas; and! Tiexas: |Proc: U.S: Nats Maus; Vols If, for 1879, spp.
292-298, pls. 2-6. Washington.

1884 Rogers, W. B. A reprint of Annual Reports and other papers on the

Geology of the Virginias. New York.

White, C. A. On Mesozoic fossils. Bull. U. S. Geol. Survey, No. 4,
pp. 1-36, pls. 1-9. Washington. Part I. Description of certain
aberrant forms of the Chamide from the Cretaceous rocks of Texas.
Part II. On a small collection of Mesozoic fossils collected in Alaska
by Mr. W. H. Dall, of the U. S. Coast Survey.

White, C. A. A review of the fossil Ostreidz of North America, and a
comparison of the fossils with the living forms. Fourth Ann. Rept.
U. S. Geol. Surv., pp. 273-430, pls. 34-82. Washington.

1885 Becker, Geo. F. Notes on the stratigraphy of California. Bull. U. S.

Geol. Survey, No. Ig.

614

1886

1887

TIMOTHV WILLIAM STANTON

Cook, Geo. H. Sketch of the geology of the Cretaceous and Tertiary
formations of New Jersey. U.S. Geol. Surv., Monog., Vol. IX, pp.
ix—xilil, and map.

White, C. A. Remarks upon certain California fossils which have been
identified with eastern species. Bull. U. S. Geol. Survey, No. 15, pp.
27-31. Washington.

Whitfield, R. P. Brachiopoda and lamellibranchiata of the Raritan
clays and greensand marls of New Jersey. Monog. U. S. Geol.
Surv., Vol. IX, pp. xvii-xx and 1-264, pls. 1-35. Washington.

Diller, J.S. Notes on the geology of northern California. Bull. U.S.
Geol. Survey, No. 33.

McGee, W J Geology of Washington and vicinity. Rept. of the
Health Officer of the Dist. of Columbia for the year ending June 30
1885, pp. 19-20, 23-25.

Shumard, Geo. G. A partial report on the geology of western Texas,
consisting of a general geological report and a journal of geological
observations along the route traveled by the expedition between
Indianola, Texas, and the valley of the Mimbres, New Mexico,
during 1855 and 1856, with an appendix giving a detailed report on
the geology of Grayson county. 145 pp. Austin.

Hill, R. T. The present condition of the knowledge of the geology of
diexas. Bull) USS. Geolaisunvey,) Now4i5:

Hill, R. T. The topography and geology of the Cross Timbers and
surrounding regions in northern Texas. Am. Jour. Sci., 3d ser., Vol.
XAXXIII, pp. 291-303.

Hill, R. T. The Texas section of the American Cretaceous. Am.
Jour. Sci., 3d ser., Vol. XXXIV, pp. 287-309.

McGee, W J. The Tuscaloosa Formation. Bull. U.S. Geol. Surv.,
No. 43, pp. 247-255.

Newberry, J. S. The Great Falls coal field, Montana. School of
Mines Quarterly, Vol. VIII, pp. 327-330.

Roemer, F. Graptocarcinus texanus, ein Brachyure aus der oberen
Kreide von Texas. Neues Jahrb. f. Geol, u. Paldont., pp. 173-176,
figs. a and J in text. Stuttgart.

Schliiter, C. Ueber die regularen Echiniden der Kreide Nordamerika’s
unter Vorlegung einer neuen Salenia. Verhand. Naturhist. Vereines,
preuss. Rheinlande, 44 Jahrg., 1 Halfte. Bonn.

Smith, E. A. and Lawrence Johnson. Tertiary and Cretaceous strata
of the Tuscaloosa, Tombigbee and Alabama rivers. Bull. U. S.
Geol. Survey, No. 43.

“White, C. A. On new generic forms of Cretaceous mollusca and their

relation to other forms. Proc. Acad. Nat. Sci., Phila., pp. 32-37,
pl. 2. Philadelphia.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 615

White, C. A. On the Cretaceous formations of Texas and their rela-
tion to those of other portions of North America. Proc. Acad. Nat.
Sci., Phila., pp. 39-47. Philadelphia.

1888 Hill, R. T. The Neozoic geology of southwestern Arkansas. Ann.
Rept. Geol. Surv., Arkansas, 1888. J.C. Branner, State Geologist.
Vol. II, pp. 1-319, pls. 1-7. Little Rock.

Hill, R.T. The Trinity formation of Arkansas, Indian Territory, and
Texas) (science, Vol. XVII, p. 21.

McGee, W J_ Three formations of the middle Atlantic slope. Am.
Jour. Sci., 3d ser., Vol. XXXV, pp. 120-143, 367-388, 448-466.

McGee, WJ The geology of the head of Chesapeake Bay. Seventh
Ann. Rep. U. S. Geol. Survey. pp. 537-646.

Marsh, O.C. Notice of a new genus of Sauropoda and other dinosaurs
from the Potomac formation. Am. Jour. Sci., 3d ser., Vol. XXXV,
pp- 89-94.

Roemer, F. Ueber eine durch die Haufigkeit Hippuritenartiger
Chamiden ausgezeichnete Fauna der oberturonen Kreide von Texas.
Palezontologische Abbandlungen herausgegeben von W. Dames und
E. Kayser, Vierter Band. No. 4, pp. 1-18 (281-296), Taf. 1-3,
(xxxi—xxxiii). Berlin.

Uhler, P. R. The Albirupean formation and its nearest relatives in
Maryland. Proc. Am. Philos. Soc., Vol. 25, pp. 42-53.

Ward, L.F. Evidence of the fossil,plants as to the age of the Potomac
formation. Am. Jour. Sci., 3d ser., Vol. XXXVI, pp. II19g-131.

1889 Becker, Geo. F. Geology of the Quicksilver deposits of the Pacific
Slope. Monog. U.S. Geol. Survey, Vol. XIII.

Cragin, F. W. Contributions to the palzontology of the plains, No. 1.
Bull. Washburn Coll. Lab. Nat. Hist., Vol. II, No. 10, pp. 65-68.
Topeka. .

Fontaine, W. M. The Potomac or younger Mesozoic Flora. Monog.
U.S. Geol. Survey, Vol. XV.

Hill, R. T. A preliminary annotated check list of the Cretaceous
Invertebrate fossils of Texas, accompanied by a short description of
the lithology and stratigraphy of the system. Geol. Surv., Texas,
Bull. No. 4, pp. 57. Austin.

Hill, R. T, Paleontology of the Cretaceous formations of Texas.
University of Texas. School of Geology. Part I, pp. 5 (not num-
bered), pls. 1-3. Austin.

Hill, R. T. A portion of the geologic story of the Colorado River of
Texas. Am. Geologist, Vol. III, pp. 287-299.

Hill, R. T. Events in North American Cretaceous history illustrated
in the Arkansas-Texas division of the southwestern region of the
United States. Am. Jour. Sci., 3d ser., Vol. XXXVII, pp. 282-290.

616

1890

1891

TIMOTHY WILLIAM STANTON

Marcou, Jules. The Jura in Texas. Proc. Boston Soc. Nat. Hist.,
Vol. XXVII, pp. 149-158.

Marcou, Jules. The original locality of Gryphea fitchert Morton.
Am. Geologist, Vol. III, pp. 188-193.

Marcou, Jules. Jura, Neocomian and Chalk of Arkansas. Am.
Geologist, Vol. IV, pp. 357-367.

White, C. A. Remarks on the genus Aucella, with especial reference
to its occurrence in California. Monog. U.S. Geol. Survey, Vol. XIII.
appendix to chap. 5, pp. 226—232, pls. 3 and 4. Washington.

White, C. A. Lower Cretaceous of the Southwest, and its relation to
the underlying and overlying formations. Am. Jour. Sci., 3d ser.,
Vol. XXXVIII, pp. 440-445.

White, C. A. The North American Mesozoic. Proc. Am. Assoc. Adv.
Sci., Vol. XX XVIII, pp. 205-226.

Whitfield, R. P. Notes on the faunal resemblance between the Cre-
taceous formations of New Jersey and those of the Gulf States.
Bull. Am. Mus. Nat. Hist., Vol. II, pp. 41-63.

Cragin, F. W. On the Cheyenne Sandstone and the Neocomian Shales
of Kansas. Bull. Washburn Coll. Lab. Nat. Hist., Vol. II, No. 11.
Also in Am. Geologist, Vol. VI, pp. 233-238; Vol. VII, pp. 179-181.

Cummins, W. F. and Lerch, Otto. A Geological Survey of the Concho
country. Am. Geologist, Vol. V, pp. 321-335.

Diller, J. S. Note on the Cretaceous rocks of northern California.
Am. Jour. Sci., 3d ser., Vol. XL, pp. 476-478.

Hill, R. T. Occurrence of Goniolina in the Comanche Series of Texas,
Non, OW Sele, excl Keey, WO, IL. 9, Ol.

Hill, R. T. A brief description of the Cretaceous rocks of Texas and
their economic value. First Ann. Rep. Geol. Survey of Texas, pp.
103-144.

Marcou, Jules. The American Neocomian and the Gryphea pitcher.
Am. Geologist, Vol. V, pp. 160-174.

White, David. Cretaceous plants from Martha’s Vineyard. Am.
Jour. Sci., 3d ser.. Vol. XX XIX, pp. 93-101. Abstract, Bull. Geol.
Soc. Am., Vol. I, pp. 554-555.

Becker, Geo. F. Notes on the early Cretaceous strata of California
ander Oregon!. Bulli GeolkaySoces Am: amGlem lu, spp Zon—2O05e
Rochester.

Clark, W. B. A revision of the Cretaceous Echinoidea of North
America. Johns Hopkins University Circular, Vol. X, No. 87, pp.
75-77. Baltimore.

Darton, N. H. Mesozoic and Cenozoic formations of eastern Virginia
and Maryland. Bull. Geol. Soc. Am., Vol. Il, pp. 431-450.
Rochester.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 617

Darton, N. H. Geology of sedimentary rocks, Washington sheet.
Guide to Washington prepared for the International Congress of
Geologists.

Hill, R. T. The Comanche Series of the Texas-Arkansas region. Bull.
Geol. Soc. Am., Vol. I], pp. 503-528. Rochester.

Newberry, J.S. The flora of the Great Falls coal field, Montana. Am.
jours Sein, 3d'ser., Vol. XI, pp. 191-201.

Taff, J. A. The Cretaceous deposits of Trans-Pecos, Texas. Second
Ann. Rept. Geol. Survey of Texas, pp. 714-738.

Turner, H.W. The Geology of Mount Diablo, California. Bull. Geol.
Soc. Am., Vol. II, pp. 383-414. Rochester.

White, C. A. Correlation papers— Cretaceous. Bull. U. S. Geol.
Survey, No. 82.

1892 Cummins, W. F. Geography, Topography, and Geology of the Llano
Estacado or Staked Plains. 3d Ann. Rep. Geol. Survey of Texas, pp.
129-223.

Dumble, E. T. Notes on the Geology of the valley of the middle Rio
Grande. Bull. Geol. Soc. Am., Vol. III, pp. 219-230. Rochester.
Fontaine, W. M. Descriptions of some fossil plants from the Great
Falls coal field of Montana. Proc. U.S. Nat. Museum, Vol. XV, pp.

487-495.

Gregory, J. W. The relations of the American and European Echinoid
faunas. Bull. Geol. Soc. Am., Vol. III, pp. 101-108. Rochester.
Hill, R. T. On the occurrence of artesian and other underground
waters in Texas, eastern New Mexico, and Indian Territory west of

the ninety-seventh Meridian.

Hill, R. T. Notes on the Texas-New Mexico region. Bull. Geol. Soc.
Am., Vol. III, pp. 85-100. Rochester.

Hollick, Arthur. The Paleontology of the Cretaceous formation on
Staten Island. Trans. N. Y. Acad. Sci., Vol. XI, pp. g6—102.

Taff, J. A. Report on the Cretaceous area north of the Colorado River.
3d Ann. Rep. Geol. Survey of Texas, pp. 269-379, and 4th Ann. Rep.,

pp. 241-354.
Uhler, P. H. Albirupean Studies. Trans. Md. Acad. Sci., pp. 185-
200.

Weed, Walter Harvey. Two Montana Coal Fields. Bull. Geol. Soc.
Am., Vol. III, pp. 301-330. Rochester.

White, C. D. The Cretaceous at Gay Head, Martha’s Vineyard. Sci-
ence; Vol Xx, ps 332:

1893 Clark, W.B. The Mesozoic Echinodermata of the United States. Bull.

U. S. Geol. Survey, No. 97, 207 pp., 50 pls. Washington.

Cummins, W. F. Tucumcari Mountain. Am. Geol., Vol. XI, pp. 375—
383.

618

1894

TIMOTHY WILLIAM STANTON

Cummins, W. F. Geology of Tucumcari, New Mexico. Science, Vol.
XXI, pp. 282-283.

Darton, N. H. The Magothy formation of northeastern Maryland. Am.
Jour. Sci., Vol. XLV, pp. 407-419. New Haven.

Diller, J.S. Cretaceous and early Tertiary of northern California and
Oregon. Bull. Geol. Soc. Am., Vol. IV, pp. 205-224. Rochester.
Dumble, E. T., and Cummins, W.F. The Kent section and Gryphea

tucumcariz Marcou. Am. Geol., Vol. XII, pp. 309-314.

Stanton, T. W. The faunas of the Shasta and Chico formations. Bull.
Geol. Soc. Am., Vol. IV, pp. 245-256. Rochester.

Calvin, Samuel. On the Geological position of Bennettites dacotensis
Macbride, with remarks on the stratigraphy of the region where the
species was discovered. Proc. lowa Acad. Sci., Vol. I, Part IV, pp-
18-22; also Am. Geologist, Vol. XIII, pp. 79-84.

Clark, W. B. Cretaceous and Tertiary Geology — Report of Progress,
1893. Geol. Surv. N. J., Ann. Rept. State Geologist, pp. 333-355.
Trenton.

Cope, E. D. Observations on the Geology of adjacent parts of Okla-
homa and northwest Texas. Proc. Acad. Nat. Sci., Phila., pp.
63-68.

Diller, J. S., and Stanton, T. W. The Shasta-Chico Series. Bull. Geol.
Soc. Am., Vol. V, pp. 435-464. Rochester.

Fairbanks, H. W. Review of our knowledge of the Geology of the Cali-
fornia Coast Ranges. Bull. Geol. Soc. Am., Vol..VI, pp. 71-102.
Rochester.

Fairbanks, H. W. Geology of northern Ventura, Santa Barbara, San
Luis Obispo, Monterey, and San Benito counties. California Mining
Bureau, 12th Ann. Rept., pp. 493-526.

Hollick, A. Cretaceous Flora of Long Island. Am. Jour. Sci., 3d Ser.
Vol. XLVII, p. 402.

Cragin, F. W. New and little known invertebrata from the Neocomian
of Kansas. Am. Geol., XIV, pp. 1-12, pl. 1.

Hill, R. T. Geology of parts of Texas, Indian Territory, and Arkansas
adjacent to Red River. Bull. Geol. Soc. Am., Vol. V, pp. 297-338.
Rochester.

Marcou, Jules. Growth of knowledge concerning the Texas Creta-
ceous. Am. Geologist, Vol. XIV, pp. 98-105.

McBride, T. H. North American Cycads. Proc. Iowa Acad. Sci., Vol
I, Part IV, pp. 62-65.

Smith, E. A. Geology of the Coastal Plain of Alabama. Geological
Survey of Alabama.

Ward, L. F. The Cretaceous Rim of the Black Hills. Journal of
Geology, Vol. II, pp. 250-266. Chicago.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 619

Williston, S. W. On various vertebrate remains from the lowermost
Cretaceous of Kansas. Kan. Univ. Quart., Vol. III, pp. 1-4.

1895 Smith, James Perrin. Mesozoic changes in the Faunal geography of
California. Journal of Geology, Vol. III, pp. 369-384.

Bibbins, Arthur E. Notes on the Paleontology of the Potomac Forma-
tion. Johns Hopkins Univ. Circular, Vol. XV, No. 121, pp. 17-20.
Baltimore. -

Clark, W. B. Cretaceous deposits of the northern half of the Atlantic
Coastal Plain. Bull. Geol. Soc. Am., Vol. VI, pp. 479-482.

Cragin, F. W. The Choctaw and Grayson Terranes of the Arietina
Colorado Coll. Studies, 5th Ann. Publication, pp. 40-48. Colorado
Springs.

Cragin, F. W. Descriptions of Invertebrate Fossils from the Comanche
Series in Texas, Kansas, and Indian Territory. Colorado Coll.
Studies, 5th Ann. Publication, pp. 49-68. Colorado Springs.

Cragin, F. W. Vertebrates from the Neocomian of Kansas. Colorado
Coll. Studies, 5th Ann. Pub., pp. 69-73, pls. 1-2. Colorado Springs.

Cragin, F. W. A Study of the Belvidere Beds. Am. Geologist, Vol.
XVI, pp. 357-385.

Cragin, F. W. The Mentor Beds: A Central Kansas Terrane of the
Comanche Series. Am. Geologist, Vol. XVI, pp. 162-165.

Dana, James D. Manual of Geology. 4th edition, pp. 812-828.

Darton, N. H. Notes on the Relations of the Lower Members of the
Coastal Plain Series in South Carolina. Am. Geologist, Vol. XVI, p
238.

Hill, R. T. On outlying areas of the Comanche Series in Kansas,
Oklahoma, and New Mexico. Am. Jour. Sci., 3d Ser., Vol. L, pp.
205-234.

Lawson, Andrew C. Sketch of the Geology of the San Francisco Pen-
insula. 15th Ann. Rept. U.S. Geol. Survey, pp. 401-476.

Le Conte, Joseph. Elements of Geology. 3d edition, pp. 469-500.’
New York.

Rauff, Hermann. Ueber Porocystis pruniformis Cragin (? Araucarites
wardt Hill) aus der unteren Kreide in Texas. Neues Jahrb. f.
Mineral., Geol. und Paldont., Bd. 1, pp. 1-18, with 1 plate.

Smith, Jas. Perrin. Mesozoic changes in the faunal geography of Cali-
fornia, Journal of Geology, Vol. III, pp. 381-382.

Smith, Jas. Perrin. Studies for Students: Geologic Study of the Migra-
tion of Marine Invertebrates. Journal of Geology, Vol. III, p. 481-
495.

Stanton, T.W. Boletin de la Comision Geologica de Mexico, Num. 1:
Fauna fossil de la Sierra de Catorce, San Luis Potosi. [Review of.]
Journal of Geology, Vol. III, pp. 858-861.

620

TIMOTHY WILLIAM STANTON

Ward, L. F. Palaobotany of Lower Cretaceous in the Black Hills.
Science, new series, Vol. I, pp. 137, 138.
Ward, L. F. The Potomac formation. 15th Ann. Rept. U. S. Geol.

Survey, pp. 313-397.

1896 Fairbanks, H.W. The Geology of Point Sal. Univ. of Cal. Bull. of

1897

the Dept. of Geol., Vol. II, pp. 1-92.

Fairbanks, H. W. The age of the Californian Coast Ranges. Am.
Geologist, Vol. XVIII, pp. 271-282.

Fontaine, W. M. The Potomac formation in Virginia. Bull. U. S.
Geol. Survey, No. 145.

Gilbert, G. K. Age of the Potomac formation. Science, new series,
Vol. IV, pp. 875-877.

Hill, R. T. A Question of Classification. Science, new series, Vol. IV,
Ppp. 918-922.

Hollick, A. The Geology of Block Island. Science, new series, Vol. IV,
Pp- 571-572.

Marcou, Jules. The Jura in the United States. Science, new series,
Vol. IV, pp. 945-947.

Marsh, O. C. The Geology of Block Island. Am. Jour. Sci., 4th ser.,
Vol. II, pp. 295-298, 375-377.

Marsh, O. C. The Jurassic formation on the Atlantic Coast. Am. Jour.
Sci., 4th ser., Vol. II, pp. 433-447.

Marsh, O. C. The Dinosaurs of North America. 16th Ann. Rept. U.
S. Geol. Survey, Part I, pp. 133-414.

Newberry, J. S. Flora of the Amboy Clays. Edited by Arthur Hollick.
Monog. U. S. Geol. Survey, Vol. XXVI.

Stanton, T. W. On the genus Remondia Gabb: A group of Cretaceous
bivalve Mollusks. Proc. U.S. Nat. Museum, Vol. XIX, pp. 299-301.
Washington.

Stanton, T. W. Contributions to the Cretaceous Paleontology of the
Pacific Coast: The Fauna of the Knoxville Beds. Bull. U. S. Geol.
Survey, No. 133. Abstract Am. Jour. Sci., 4th ser., Vol. I, pp. 320—
22K.

Stanton, T. W., and T. Wayland Vaughan. Section of the Cre-
taceous at El Paso, Texas. Amer. Jour. Sci., 4th ser., Vol. 1, pp.
21-26.

Ward, Lester F. Some analogies in the Lower Cretaceous of Europe
and America. 16th Ann. Rept. U.S. Geol. Survey, Part I, pp. 463-
542.

Clark, W. B. Physical features of Maryland. Md. Geol. Survey, Vol.
levRattallils

Clark, W. B., and Bibbins, Arthur. The stratigraphy of the Potomac
Group in Maryland. Journal of Geology, Vol. V, pp. 479-506.

Il.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 621

Hollick, A. Geological Notes: Long Island and Block Island. Trans.
N.Y. Acad. Ser, Vol. XVI, pp. 9-18.

Prosser, Chas. S. The Upper Permian and Lower Cretaceous [of
Kansas], Univ. Geol. Survey Kansas, Vol. II, pp. 51-194. Topeka.

Ward, Lester F. Professor Fontaine and Dr. Newberry on the age of
the Potomac formation. Science, new series, Vol. V, pp. 411-419.

PAPERS ON RELATED FOREIGN FORMATIONS AND MISCELLANEOUS
REFERENCES.

1839 Galleotti, H. Notice sur le calcaire crétacé des environs de Jalapa, au

Mexique. Bull. Soc. Geol. France, Vol. X, pp, 32—39. Paris.

1840 Nyst, H., and Galeotti, H. Sur quelques fossiles du Calcaire Jurassique

de Tehuacan, au Mexique. Bull. Roy. Acad. Bruxelles, tome, 7, Part
IT, pp. 212-221.

1849 Buch, L. von. Betrachtungen ueber die Verbreitung und die Grenzen

der Kreidebildungen. Verhandl. des Naturhist. Vereins der preuss.
Rheinlande und Westphaliens, Bd. 7, pp. 211-242.

1858 Pictet, F. J., et Renevier, Eugéne. Description des fossiles du terrain

Aptien de la perte du Rhone et des environs de Ste. Croix. Mat.
pour la Paléont. Suisse, 1° Serie.

1858-73 Pictet, F. J., et G. Campiche. Description des fossiles du terrain

Crétacé des environs de Sainte Croix. Materiaux pour la Paléont.
Suisse. Series 2-6. Genéve.

1866 Coquand, H. Monographie paléontologique de l’étage Aptien de l’Es-

pagne. Marseilles.
Rémond, A. Notice of geological explorations in northern Mexico,
Proc. Cal. Acad. Sci. Vol. III, pp. 244-257.

1868 Verneuil, E. de, et G. de Loriére. Description des fossiles du Neoco-

mian superieur de Utrillas et ses environs. Paris.

1871 Neumayr, M. Der Penninische Klippenzug. Jahrb. d. k. k. Geol.

Reichsanstalt, Bd. 21, pp. 451-536. Wien.

1872 Gabb, W. M. Notice of a collection of fossils from Chihuahua, Mexico,

Proc. Acad. Nat. Sci. Phila., pp. 263-265, pls.g-11. Philadelphia.
Neumayr, M. Ueber Jura-Provinzen. Verhandl. k. k. Geol. Reichs-

anstalt, pp. 54-57.

1873 Billings E. On the Mesozoic fossils from British Columbia. Geol. and

Nat. Hist. Surv. of Canada, Rept. for 1872-3, Appendix II, pp.
71-75.
Neumayr, M. Ueber Charakter und Verbreitung einigen Neokomce-
phalopoden. Verhandl. k. k. Geol. Reichsanstalt, pp. 288-291.
Richardson, James. Report on the coal fields of Vancouver and
Queen Charlotte Islands. Rept. Geol. Survey, Canada, for 1872-3,

pp. 32-65.

622

1876

1877

1878

1879

1880

1881

1882

1883

TIMOTHY WILLIAM STANTON

Whiteaves, J. F. On some invertebrates from the coal-bearing rocks
of the Queen Charlotte Islands, collected by Mr. James Richardson.
Geol. Surv. Canada, Mesozoic fossils, Vol. I, Part I, pp. I-92, pls.
1-10, Montreal.

Barcena, M. Materiales para la formacion de una obra de Paleontolo-
gia Mexicana. An. Museo. Nac. Mex. Tome |, pp. 85-91, 195-202,
283-286. Mexico.

Dawson, Geo. M. Report on explorations in British Columbia. Geol.
Surv. Canada, Rept. for 1875-6, pp. 233-265.

Gabb, W. M. Description of a collection of fossils made by Dr. Rai-
mondi in Peru. Jour. Acad. Nat. Sci. Phila., 2d ser. Vol. VIII, pp.
263-336.

Neumayr, M. Ueber unvermittelt auftretende Cephalopodentypen im
Jura Mittel-Europa’s. Jahrb. k. k. geol. Reichsanstalt, pp. 37-80.
Dawson, Geo. M. Preliminary report on the physical and geological
features of the southern portion of the interior of British Columbia.

Geol. Surv. Canada, Rept. for 1877-8, pp. 1-173 B.

Dawson, Geo. M. Sketch of the geology of British Columbia. Cana-
dian Naturalist, Vol. IX, pp. 445-447.

Dawson, Geo. M. Report on the Queen Charlotte Islands. Geol.
Surv. Canada, Rept. for 1878-9, pp. I-IoI.

Ramirez, S. Informe que como resultado de su exploracion en la
Sierra Mojada. An. Min. Fomento Rep. Mex. tome 3, pp. 627-687,
Lam. 1-4. Mexico.

Dawson, Geo. M. Geology of British Columbia. Geol. Mag., Dec. 2,
Vol. VIII, pp. 156-162, 214-227.

Steinmann, G. Tithon und Kreide in den peruanischen Anden. Neues.
Jahrb. f. Mineralogie, etc. Bd. 2, pp. 130-153.

Steinmann, G. Zur Kenntniss der Jura- und Kreide-formation von
Caracoles. Neues. Jahrb. f. Mineral, etc. I Beilageband, pp. 239-
301.

White, C. A. Description of a very large fossil gasteropod from the
state of Pueblo, Mexico. Smithsonian Misc. Coll., Vol. XXII, pp.
140-142, pls. 2. (Proc. U. S. Nat. Museum, Vol. III.) Washington.
Spanish translation in La Naturaleza, t. 6, 1884, pp. 219-221.

Steinmann, G. Ueber Jura und Kreide in den Anden. Neues. Jahrb. f.
Mineralogie, etc., Bd. 1.

Urquiza, M. Exploracion del Distrito de Coalcoman, Estado de Mich-
oacan. Ann. Min. Fomento Rep. Mex., Tome 7, pp. 195-261.
Mexico.

Neumayr, M. Ueber klimatische Zonen wahrend der Jura- und Krei-
dezeit. Denkschr. k. Akad. d. Wissenschaften, Math.-Naturw.
Classe. Bd. 47, pp. 1-34.

LOWER CRETACEOUS FORMATIONS AND FAUNAS 623

Whiteaves, J. F. On the Lower Cretaceous rocks of British Columbia.
Proc. and Trans. Roy. Soc. Canada, Vol. I, sec. 4, pp. 81-86 (three
wood cuts). Montreal.

1884 Whiteaves, J. F. On the fossils of the coal-bearing deposits of the
Queen Charlotte Islands, collected by Dr. G. M. Dawson. Geol. and
Nat. Hist. Surv., Canada. Mesozoic Fossils, Vol. I, Part III, pp. tg1—
262. Montreal.

1885 Choffat P. Recueil de Monographies Stratigraphiques sur le Systeme
Crétacique du Portugal. Commission des Travaux géologiques du
Portugal, 68 pp. 3 pls. Lisbonne.

Dawson, J. W. On the Mesozoic floras of the Rocky Mountain region
in Canada. Trans. Roy. Soc. Canada, Vol. III, Sect..4, pp. 1-22.

Whiteaves, J. F. Notes on some Mesozoic fossils from various local-
ities on the coast of British Columbia, for the most part collected by
Dr. G. M. Dawson. Geol. and Nat. Hist. Surv. Canada, Vol. II (new
series). Ann. Rept. for 1886, pp. 108-114.

1886 Choffat, P. Recueil d’études paléont. sur le Systeme Crétacique du
Portugal. Commission des Travaux géologiques du Portugal, 40
pp., 18 pls. Lisbonne.

Dawson, G. M. Preliminary report on the physical and geological
features of that portion of the Rocky Mountains between Lat. 49° and
50° 30’. Ann. Rept. Geol. Surv, Canada, new series, Vol. I, Part B.

Dawson, J. W. Cretaceous floras of the Northwest. Canadian Record
of Science, Vols Tipp: 1-0:

Karsten, Herman. Geologie de l’ancienne Columbie Bolivarienne,
Venezuela, Nouvelle-Grenade et Ecuador. Avec huit planches et
une carte géologique. Berlin.

1887 McConnell, R.G. On the geological structure of a portion of the
Rocky Mountains. Geol. Surv. Canada, Ann. Rept. for 1886, pp. 7—
40D.

Neumayr, M. Erdgeschichte, Bd. 2, pp.342-394.

1889 Dawson, G. M. On the earlier Cretaceous rocks of the northwestern
portion of the Dominion of Canada. Am. Jour Sci., 3d ser., Vol. 38,
pp. 120-127.

Whiteaves, J. F. On some Cretaceous fossils from British Columbia,
the Northwest Territory, and Manitoba. Cont. to Canadian Paleont.,
Vol. I, Part II, pp. 151-196, pls. 20-26. Montreal.

1890 Cotteau, Gustave. Note sur quelques echinides du terrain crétacé du
Mexique. Bull. Soc. Géol. France, 3d ser. Vol. XVIII, pp. 292-299,
pls. 1 and 2. Paris.

Heilprin, Angelo. The geology and paleontology of the Cretaceous
deposits of Mexico. Proc. Acad. Nat. Sci. Phila., pp. 445-469, pls.
12-14 [11-13]. Philadelphia.

624 TIMOTHY WILLIAM STANTON

1891 Felix, J. Versteinerungen aus der mexicanischen Jura- und Kreide-
Formation. Beitrage zur Geologie und Palzontologie der Republik
Mexico, von J. Felix und H. Lenk. Palzontographica, Bd. 37, pp.
(24-78), 140-194, pls. 22-29. Stuttgart.

Steinmann, Gustav. Sketch of the geology of South America. Am.
Naturalist, Vol. XXV, pp. 825-860.

1893 Dawson, J. W. Fossil Floras and Climate. Nature, Vol. XLVII, p.
d/

Dawson, J. W. The correlation of early Cretaceous floras in Canada
and in the United States. Trans. Roy. Soc. Canada, Vol. X, sec. 4,
PP- 79-93-

Hill, R. T. The Cretaceous Formations of Mexico and their relations
to North American geographic development. Am. Jour. Sci., 3d ser.,
Vol. XLV, pp. 307-324.

Kayser, E. Text-Book of Comparative Geology. Translated by Philip
Lake. London.

Whiteaves, J. F. Description of two new species of Ammonites from
the Cretaceous rocks of Queen Charlotte Islands. Canadian Rec. of
Sci., Vol. V., pp. 441-446.

Whiteaves, J. F. The Cretaceous System in Canada. Trans. Roy. Soc.
Canada, Vol. XI., sec. 4, pp. 3-19.

1894 Kossmat, Franz. Die Bedeutung der Siidindischen Kreide-formation fiir
die Beurtheilung der geographischen Verhdltnisse wahrend des spa-
teren Kreidezeit. Jahrb. d. k. k. geol. Reichsanstalt, Bd. 44, pp. 459-
478. Wien.

1895 Castillo, Antonio del, et J. G. Aguilera. Fauna fosil de la Sierra de
Catorce, San Luis Potosi. Bol. de la Com. Geol. de Mexico, No. 1.

Gill, A. Capen. A geographical sketch of the Sierra Tlayacac, in the
state of Morelos, Mexico. Am. Geologist, Vol. XVI, p. 240.

Steinmann, G., W. Deecke, and W. Moricke. Das Alter und die Fauna
des Quiquirina Schichten in Chile. Beit. zur Geologie u. Palont.
von Siidamerika, III. Neues Jahrb. f. Min. Geol. und Palzont. Bei-
lage Bd x, pp. 1-118, pls. 1-8.

1896 Choffat, Paul. Coup d’oeil sur les mers mesozoiques du Portugal.
Vierteljahrssch. der Naturforsch. Gesellsch. in Zurich. aus Jahrgang
XLI, pp. 294-317.

1897 Aquilera, J. G. Sinopsis de Geologia Mexicana. Bol. de la Com. Geol.
de Mexico, Nos. 3-6, pp. 189-226.

TimotHy WILLIAM STANTON.

CORRELATION, OF THE, DEVONIAN FAUNAS IN
SOUTHERN ILLINOIS.

INTRODUCTION.

Tue Devonian faunas of the interior of America are of two
distinct types, and occur in two more or less distinct geological
provinces. The eastern interior province is typically represented
in New York; it extends westward into Canada and southwest-
ward into the Ohio valley. The western interior province is
typically represented in Iowa; it extends to the northwest into
British America and is connected with the European region.
The southern Illinois Devonian is of much interest because of its
geographic position between the New York and the Iowan areas,
but in all the study which has hitherto been devoted to the
region, it has never been definitely shown with which one of
these provinces it is connected. Recent investigation shows the
Devonian faunas in southern Illinois to be intimately related to
the New York faunas, and that the strata containing them are
but a western extension of the formations of the eastern province.

The ‘“ Devil’s Back Bone” and the ‘“ Devil’s Bake Oven,” near
Grand Tower, in Jackson county, Illinois, have long been recog-
nized as localities rich in Devonian fossils. In 1855 Norwood
and Pratten’ described as new several species of Chonetes from
this locality. In 1867 Hall made frequent mention, in Vol. IV of
the Paleontology of New York, of the occurrence of species of
brachiopods at the ‘‘ Bake Oven,” Jackson county, IIlinois, anda
few were described from this locality exclusively. In 1868 the
geology of Jackson county was published in Vol. HI of the
Geological Survey of Illinois, several sketches of the ‘Bake
Oven” and the ‘‘Back Bone” being reproduced and mention
being made of the fossils collected. In the same volume are

tJour. Acad. Nat. Sci., Phil., ser. 2, Vol. III, pp. 23-32.
625

626 SLUART, WHEELER:

descriptions and illustrations of several species of fossils from the
locality.

The ‘ Back Bone”’ is a narrow, rocky ridge, rising about one
hundred feet above river level and extending northward from
the town of Grand Tower along the east bank of the Mississippi
River for a distance of about one-half mile. It consists of strata
of Devonian limestone, with beds which are probably of Lower
Helderberg age below, dipping to the northeast at an angle of
about.25°. @her< Bake Ovenkyus weally the northempendyor
this ridge, but is isolated from the main ‘‘Back Bone” by an
interval of several hundred feet.

The field work upon which the present paper is based was
done in August 1896. As the time which could be devoted to
the work was limited, it was concentrated upon the north face of
the “Bake Oven.” The section here studied is about 167 feet
in thickness. An attempt was made to select the fossil-bearing
zones in the section, and to make as complete collections from
them as the time would allow. Twenty-six zones were recog-
nized, eighteen of them being fossil-bearing to a greater or less
extent. Additional time in the field would doubtless materially
increase the number of species, and perhaps the number of zones,

”)

and a careful examination of the entire ‘‘ Back Bone’’ would be

exceedingly valuable.

DESCRIPTION OF THE SECTION, WITH LISTS OF FOSSILS.

The field number given to the section was 5A. The beds,
with their fossil contents, will be described, beginning with the
lowest, 5A* and passing upward through the successive zones to
5A”, which is the highest. The relative abundance of the
species is designated as follows: (a) abundant, (c) common,
(Ge), aves,

5A* About fifteen feet of coarsely crystalline, gray limestone exposed,
variable in texture, and often more or less arenaceous, especially near the
top. Fossils numerous but not well preserved.

1. Leptena rhomboidalis Wilck. (c).
2. Chonetes laticosta Hall? (r).

5A?

CORRELATION OF THE DEVONIAN FAUNAS 627

. Orthis (Rhipidomeltla) semele Hall ? (a).
. Rhynchonella sp. (r).

. Eatonia sp. (1).

. Cyrtina hamiltonensts Hall (r).
. Spirifer macrothyris Hall (c).

. Spirifer raricostus Conrad (c).
. Nucleospira elegans Hall? (r).

. Nucleospira ventricosa Hall (r).
. Mertstella sp. (Cc).

. Platyceras sp. (a).

. Orthoceras sp. (r).

. Phacops cristata Hall? (1).

. Corad, fragments (r).

. Bryozoa, fragments (c).

V7

Fish teeth, fragments (r).

Two and one-half feet of rather coarse, light-colored sandstone.

Fossils similar to those in the bed below, but poorly preserved.
1. Leptena rhomboidalis Wilck. (c).

Oo ON Am fW N

5A?

. Chonetes laticosta Hall (r).

. Orthis (Rhipidomella) semele Hall ? (c).
. Eatonia sp. (r).

. Spirifer macrothyrts Hall ? (r).
SSPErLfEr SP. (x):

. Nucleospira elegans Hall ? ? (r).

. Platyceras sp. (a).

. Dalmanites sp. (r).

Forty-five feet of impure, thin, irregularly bedded, dark limestone,

variable in texture, and affording no fossils. Doubtless a more thorough
examination of these beds would disclose a more or less abundant fauna.

5A*

Six inches of impure, shaly limestone, lighter colored than that

below and much decomposed upon the surface. Fossils poorly preserved.

ie
. Chonetes laticosta Hall (r).

. Orthis (Rhipidomeltla) sp. (Cc).

. Rhynchonella sp. (x).

. Centronella glans-fagea Hall (r).
. Spirifer duodenaria Hall (c).

. Spirifer sp. (r).

. Platyceras sp. (r).

. Pleurotomaria ? sp. (r).

. Phacops cristata Hall ? (r).

. Bryozoa, fragments (a).

=H OO ON Am ff WwW N

—

Pholidostrophia nacrea Hall (r).

628

STUART WELLER

5A 5%. Ten inches of dark brown, impure, limestone, with chert nodules.

Nm PW YN

. Productella spinulicosta Hall (r).

. Dielasma ? sp. (x).

. Spirifer griert Hall (r).

. Platyceras, cf. young of P. bucculentum Hall (r).
. Phacops cristata Hall ? (r).

. Bryozoa, fragments (a).

5A°. Four and one-half feet of unevenly bedded, partially crystalline,

impure brown limestone.
1. Strophodonta patersoni Hall (c).

CON OA” PW N

. Strophonella ampla Hall (1).

. Chonetes mucronata Hall (a).

. Orthis (Rhipidomella) vanuxemi Hall var? (r).
. Orthis (Schizophoria) propingua Hall (a).
. Atrypa reticularis Linn. (c).

. Cyrtina hamiltonensts Hall (r).

. Spirifer griert Hall (r).

. Paracyclas elliptica Hall (r).

. Platyceras sp. (C).

. Lichas (chonolichas) ertopsts Hall? (r).

. Phacops cristata Hall? (r).

Tae

Cystodictya sp. (a).

5A’. Six feet four inches of thin, unevenly bedded gray-brown limestone
nearly identical in lithological characters with the last.
1. Strophodonta patersoné Hall (c).

Nm & WW N

. Chonetes mucronata Hall (a).

. Orthis (Rhipidometla) vanuxemt Hall var? (c).
. Atrypa reticularis Linn. (c).

. Spirifer varicosus Hall (r).

. Nucleospira concinna Hall? (r).

5A®. One foot four inches of impure, semicrystalline, brown limestone with
numerous fragments of corals too imperfectly preserved for identification.

5A°%. Three feet of limestone similar to the last but without fossils.

GALS
Ite
2,
GALE

One foot of limestone similar to the last.

Strophodonta concava Hall (r).

Corads, imperfect fragments (a).

Three feet ten inches of hard, brittle, semicrystalline, much frac-

tured limestone, with an abundant fauna.

Ie
2. Strophodonta concava Hall (a).

ay

4. Strophodonta inequistriata Conrad (c).

Strophodonta patersont Hall (a).

Strophodonta perplana Conrad (c).

CORRELATION OF THE DEVONIAN FAUNAS 629

5. Strophodonta demissa Conrad (r).
6. Pholidostrophia nacrea Hall (r).
7. Leptena rhomboidalis Wilck. (r).
8. Orthothetes chemungensis Conrad var. arctostriata Hall (r).
9. Orthothetes chemungensis Conrad var. pandora Billings (c).
10. Chonetes mucronata Hall (a).
11. Productella spinulicosta Hall (r).
12. Orthis (Rhipidomella) vanuxemi Hall var.? (a).
13. Orthis (Schizophoria) propingua Hall (r).
14. Rhynchonella louisvillensis Nettelroth ? (r).
15. Rhynchonella cf. horsfordi Hall (1).
16. Rhynchonella (Pugnax) sp. (r).
17. Atrypa reticularis Linn. (a).
18. Cyrtina hamiltonensts Hall (a).
19. Spirifer varicosus Hall (a).
20. Spirifer duodenaria Hall (c).
21. Nucleospira concinna Hall (r).
22 Paracyclas elliptica Hall (r).
23. Modiomorpha ? cf. M. recta Hall (r).
24. Grammysia cf. rhomboidalis M. & W. (r).
25. Conocardium cuneus Conrad (c).
26. Aviculopecten sp. (a).
27. Pterinea sp. (r).
28. Pterinea flabellum Conrad ? (r).
29. Platyceras bucculentum Hall ? (c).
30. Callonema lichas Hall ? (c).
31. Loxonema ? cf. L. pexatum Hall ? (c).
32. Bellerophon 2 sp. (r).
33. Lichas (Ceratolichas) cf. grypes Hall (r).
34. Dalmanites cf. calypso Hall cf. erina Hall (c).
35. Phacops cristata Hall? var. (1).
36. Zaphrentis ? imperfect fragments (c).
37. Bryozoa fragments (c).
38. Fash Teeth fragments (r).
5A, Nine feet of impure, brown limestone with thin bands of chert.
No fossils collected.
5A%, Five feet of limestone similar to the last.
. Strophodonta perplana Conrad (c).
. Strophodonta demissa Conrad (r).
. Strophodonta ineguiradiata Hall (c).
. Orthothetes chemungensts Conrad var. pandora Billings (c).
. Chonetes mucronata Hall (a).

mn & Ww N et

630

5AM.

STUART WELLER

. Productella Spinulicosta Hall (r).

. Pentamerella cf. arata Conrad (r).
. Rhynchonella sappho Hall (r).

. Rhynchonella cf. horsfordi Hall (r).
. Dielasma ? sp. (1).

. Atrypa reticularis Linn. (a).

. Spirifer sp. (x).

. Paracyclas elliptica Hall (r).

. Phacops cristata Hall? var. (r).

. Bryozoa, fragments (a).

Twenty feet of impure brown limestone, variable in character and

texture, thin bedded and shaly in part.

5A.

oO ON AM FW N

5A 16

Am PW N

GACT.
lected.
5A 18

Five feet of impure reddish brown limestone.

. Strophodonta concava Hall (a).
. Strophodonta demissa Conrad (c).

Leptena rhomboidalis Wilck. (a).

. Chonetes cf. deflecta Hall (a).

. Orthis (Rhipidomella) vanuxemt Hall (c).
. Paracyclas elliptica Hall (r).

. Bellerophon sp. (x).

. Gomphoceras lunatum Hall? (c).

. Gomphoceras tmpar Hall? (c).

Three feet ten inches of brown limestone.

. Strophodonta ineguiradiata Hall (r).

. Chonetes cf. deflecta Hall (r).

. Orthis (Rhipidomella) vanuxemi Hall? var. (a).
. Orthis (Schizophoria) ? sp. (a).

BU SDL72Z/C7a Sp (G):

. Paracyclas elliptica Hall (r).

Five feet five inches of impure brown limestone. No fossils col-

Three feet six inches of impure, reddish-brown limestone, com-

posed almost wholly of a single species of Chometes.

N OW SW YN &

GAG

. Chonetes yandellana Hall (a).

. Productella spinulicosta Hall ? (r).

. Productella sp. (r).

. Camarophoria sp. (r).

. Dielasma cf. D ? navicella Hall (r).
. Paracyclas elliptica Hall (r).

. Platyceras sp. (x).

Nine feet of impure brown limestone with few fossils.

BA:

species of

The

2

siren
fossils.

FIN

5A,
stone with

ON AM SW NN

aes

CORRELATION OF THE DEVONIAN FAUNAS 631

Two feet impure shaly brown limestone with multitudes of a single
Chonetes.

Chonetes littont N. & P.? (a).

Spirifer fornaculus M. & W. (r).

Six feet of impure, thin bedded, brown limestone with few

Six inches impure brown limestone.

. Pholidostrophia nacrea Hall (a).
. Productella spinulicosta Hall (r).
. Dielasma sp. (tr).

. Atrypa reticularis Linn. (r).

. Spirifer ziczac Hall ? (a).

. Spirifer fornaculus M, & W. (r).
. Favosites ? sp.(r).

Three feet of dark, often nearly black, somewhat siliceous lime-
many fossils.

. Strophodonta ineguiradiata Hall (a). :
. Strophodonta demissa Conrad (c).

. Pholidostrophia nacrea Hall (a).

. Leptena rhomboidalis Wilck. (a).

. Chonetes deflecta Hall (a).

. Chonetes pusitla Hall (a).

. Orthis (Schizophoria) towensis Hall (c).
. Spirifer fornaculus M. & W. (c).

. Athyris vittata Hall (c).

. Paracyclas elliptica Hall (c).

. Paracyclas lirata Conrad (r).

. Pleurotomaria sp. (c).

. Bellerophon sp. (r).

. Orthoceras sp. (r).

. Phacops rana Green (a).

. Proetus rowit Green (r).

. Zaphrentis? sp, (1).

. Cystodictya sp. (a).

Nine feet of unexposed, covered at the time of examination with

mud and water.

5A,
sively of s
Te

Fe

Bh

Three feet of dark brown impure limestone made up almost exclu-
pecimens of Chonetes coronata.

Chonetes coronata Hall (a).

Tropidoleptus carinatus Conrad (a).

Spirifer fornaculus M. & W. (a).

632 SLOARD WEEE ET:

4. Bellerophon sp. (r).
5. Gyroceras cf. trivolve Conrad (r).
6. Tentaculites bellulus Hall? (c).
7. Phacops rana Green (c).
8. Proetus canaliculatus Hall (r).
9. Zaphrentis sp. (x).
0. Cystodictya sp. (Cc).
5A*, Four inches of impure brown limestone like the last, but with few
specimens of Chonetes coronata.

1. Orthothetes chemungensts Conrad var pandora Billings (r) .
2. Chonetes coronata Hall (c).

3. Spirifer fornaculus M. & W. (a).

4. Gomphoceras sp. (r).

DISCUSSION OF THE FAUNAS.

From a general survey of the entire fauna of the section,
seven conspicuous divisions may be recognized. The first of
these include zones 5A’ and 5A? The conspicuous species are
Orthis (Rhiphidomella) semele ? and Platyceras sp. Orthis (Riupid.)
semele was originally described by Hall from very imperfect
material found in the Onondaga limestone in Erie county, N. Y.
The Illinois specimens are not perfectly preserved, but seem to
agree more nearly with this species than with any other. The
Platyceras is of a type which might be present in any fauna from
the Lower Helderberg to the Hamilton inclusive. Well preserved
specimens of spirifer macrothyris and spirifer raricostus are present,
which are good Upper Helderberg species. Associated with these
are Nucleospira ventricosa and Nucleospira elegans? which were
described from the Lower Helderberg, and an undescribed
species of Zatonta, which genus has not hitherto been recognized
above the Oriskany. There is no fauna comparable to this one
in the western interior Devonian province, but in the eastern
province this association of species is about equivalent to the
lower half of the Upper Helderberg group in the New York
series.

The second division of the general fauna includes zones 5A*
to 5A. The association of species in these zones is a typical

CORRELATION OF THE DEVONIAN FAUNAS 633

Corniferous limestone fauna, as seen in Indiana, Ohio, and New
York. The conspicuous species in the fauna are the large and
robust Strophodontas, the Atrypa reticularis of the large, robust
form so common at the falls of the Ohio, Spurifer varicosus,
Spirifer duodenaria, Orthis (Schizophoria) propinqua, Paracyclas
elliptica, Conocardium cuneus, Lichas (Ceratolichas) cf. grypes,
Dalmanites cf. calypso cf. erina, etc. Nowhere in the western
interior province does a fauna at all allied to this one occur,
but it is identical with the Corniferous fauna of the eastern
province.

The third division may be called the Gomphoceras zone, and
includes only the bed numbered 5A*. It is characterized by
numerous specimens of several large, robust species of Gompho-
ceras. The specimens as they occur on the surface of the out-
crop are generally too imperfect for certain identification, but
are of a general type of the genus which is common in both the
Corniferous and the Hamilton faunas. The associated species
are nearly all identical with those in the Corniferous fauna
below.

The fourth division is the Chonetes yandellana zone, 5A™.
The bed is made up almost exclusively of multitudes of speci-
mens of this one species, all the others recorded being rare or
uncommon.

The fifth division is the Chonetes littont? zone, 5A*. It is
similar to the Chonetes yandellana zone in being made up almost
entirely of great numbers of individuals of a single species of
Chonetes. C. littont, with three other species of the same genus,
was originally described from this locality by Norwood and
Pratten, but their descriptions and figures are so imperfect that
it is difficult to recognize their species. In the faunas of the sec-
tion there are three conspicuous Chonetes zones, each containing
exclusively a single species of the genus. Three of Norwood
and Pratten’s species, C. macluret, C. martini, and C. tuomyt, may
be certainly identified as different stages of a single species, C.
coronatus, which characterizes the uppermost Chonetes zone. The
chances are, therefore, that their fourth species, C. /ittoni, is

634 SLUART WELLER

either one or the other of the two additional conspicuous species
at the locality, and from careful examination and comparison of
the specimens, descriptions and figures, it seems most probable
that the species occurring in such numbers in zone 5A ” is the C.
littont of these authors.

The sixth division is zone 54 *3, and has a fauna quite differ-
ent from any of those below. Leptena rhomboidalis is the most
abundant species. Some of the additional conspicuous species
are Chonetes deflecta and Chonetes pusilla, which are apparently
variations of a single species, Pholidastrophia nacrea, Athyris vittata
of the type common at the falls of the Ohio, Phacops rana, Para-
cyclas elliptica and Paracyclas lirata. As a whole the fauna is of
a Hamilton facies, but is more like the Hamilton fauna at the
falls of the Ohio than the typical New York fauna. Orthis
(Schizophoria) towensis is an uncommon species which is con-
spicuous in the Devonian faunas of Iowa, but is absent from the
New York faunas until after the incursion of the Chemung faunas
from the west.

The seventh and last division is zone 5A *5,and may be termed
the Chonetes coronata zone. The bed is made up of multitudes
of individuals of Chonetes coronata, with perhaps one-tenth as
many individuals of 7vopidoleptus carinatus. Both of these species
are peculiar forms and are characteristic of the New York Hamil-
ton. They appear suddenly both in the New York and the Illinois
localities without any known forerunners. Tvopidoleptus carina-
tus is an abundant species in the South American Devonian
faunas, and Chonetes coronata is of a type otherwise unknown in
North America, but common in South America, where it is
represented by C. arcet Ulr., C. riickt Ulr., and other species. There
is evidence in the Hamilton fauna of the east-American province
of an immigration from the southern hemisphere which did not
affect the western Devonian faunas. The details of this epoch
in Devonian history are not yet fully understood, but the pres-
ence of this Chonetes coronata and Tropidoleptus fauna marks the
point where this immigration first made itself felt in the south-
ern Illinois region.

CORRELATION OF THE DEVONIAN FAUNAS 635

CONCLUSION.

It is believed that the facts here set forth satisfactorily
demonstrate that the Devonian faunas in southern IIlinois are not
related to the Iowan Devonian faunas as has sometimes been
suggested, but are a western extension of the faunas of the New
York province. Atthe “ Bake Oven” section the fauna of the
lowest beds is of an age corresponding to the lower portion of the
Upper Helderberg period, while the uppermost faunas are of
Hamilton age. The line of demarkation between the Upper
Helderberg and Hamilton faunas cannot be exactly drawn, but
it comes somewhere between zones 54 %5 and 5A *3.

In conclusion I wish to acknowledge the assistance given by
Mr. A. W. Slocom, who has skillfully prepared the material for
study.

STUART WELLER.
THE UNIVERSITY OF CHICAGO.

VION TU OIRICAIE,

THE attendance at the Detroit meeting of the American
Association for the Advancement of Science was notably smaller
than usual, a result doubtless due in part to the meeting of the
British Association at Toronto which followed at such an inter-
val as to invite busy men to select the one at the expense of the
other. The attendance upon the geological section was also
adversely affected by the International Congress at St. Peters-
burg. The papers presented, however, were perhaps even more
than usually important and interesting. The location of the
meeting naturally invited an unusual number of papers relative
to the problems of the Great Lake Basins and these easily
took precedence. The widest popular interest was undoubtedly
called forth by Mr. Gilbert’s announcement of a definite tilting
of the area of the lake basins towards the southwest. His deduc-
tion that the rate of change amounted to five inches per hundred
miles per century, and his prophecy that at a specified date the
drainage would be reversed, Niagara abandoned, and Detroit and
Chicago flooded, naturally created something akin to a sensation
in the great cities of the lakes. Incidentally this contribution
to prophetic geology is having a good effect in removing the too
wide impression that geology is a science of the ancient earth.
The present and future belong to it as much as the past. The
activity of recent years in current geomorphy is helping to
awaken an appreciation of contemporaneous geology. A few
decisive predictions will doubtless establish the value of prog-
nostic geology.

This is not the first time that Mr. Gilbert has essayed the
role of geological prophet, but it is, we believe, the first instance

in which he has given us a definite time factor which holds out
636

EDITORIAL 637

the prospect that we may be able to bring him face to face with
his responsibilities at a fixed day of fulfillment, though his dates
are inconveniently distant. A prophecy which definitely courts
atest of its accuracy by giving dates and amounts has a grateful
moral flavor. The prospect of honor for fulfillment and punish-
ment for failure is equitably distributed. Writing from this
doomed locality we cannot lay claim to that indifference to results
which is the prerequisite of complete impartiality in weighing
the merits of the prophecy, but we have this comforting alterna-
tive that whatever the outcome we shall be able either to rejoice
in the triumph of a friend or else join in the laugh of our neigh-
bors at his failure.
*

OnE of the features of especial interest at the Detroit meet-
ing was the joint session of the anthropological and geological
sections for the discussion of the relics of man found on the Dela-
ware at Trenton, N. J., participated in by Putnam, Knapp, Kim-
mel, Wright, Holmes, Mercer, Wilson and Salisbury. Previous
to the meeting all of these participants had visited the ground
where excavation under the direction of Professor Putnam has
been for some time in progress, and were thus armed with fresh
facts from personal observation. The good influence of the
“higher criticism’ was manifest in the great care obviously taken
in making and presenting the observations and in the critical and
cautious attitudes assumed in their interpretation. The discus-
sion was an altogether admirable one and formed an important
episode in the progress of anthropic geology in this country.
The discussion was essentially confined to the interpretation of a
surface bed of sand three or four feet thick embracing scattered
pebbles and irregular seams of ferruginous and silty materials, and
of the artifacts found in it. This superficial bed rests upon the
glacial gravels and lies on the brink of the terrace which overlooks
the Delaware bottoms. The geological discussion centered upon
the origin of this sandy deposit. The majority opinion and the
weight of evidence seemed on the whole to favor a wind origin.
No substantial evidence that it was of glacial or glacio-fluvial

638 EDITORIAL

origin, or that it was contemporaneous with any part of the ice
age was presented. The anthropological discussion centered
upon the question whether any civilization different from that of
the early Algonkian Indians was shown by the relics. The for-
mer contention that the base of the deposit only carries argillite
artifacts, while the upper carries quartz and jasper flakes also,
was weakened by the reporting of a few jasper and quartz chips
from the lower part. The hypothesis that the artifacts are
paleolithic was weakened by the discovery of a small arrowhead
in the heart of the deposit. On the whole the discussion seemed
to leave the general impression that the evidence of any very
ancient or very primitive form of civilization at this locality is of
a quite slender and doubtful nature. The hypothesis of a glacial
man was scarcely in serious discussion although incidentally
alluded to, there being no proof that the beds are of glacial age.
No new evidence of relics in the undoubted glacio-fluvial beds
below was presented.
*

Avr the Toronto meeting a similar joint session was held at
which the broader subject of ancient man in America was dis-
cussed. The added point of interest there was the attitude of the
British geologists and archeologists who are familiar with the
character of the evidence in Europe where the antiquity of man
is not seriously questioned. Their general disposition toward
the evidence presented was that of marked conservatism. The
foreign anthropologists and geologists seemed keenly alive to the
inherent incongruities and self-destructive aspects of much of the
supposed evidence for the great antiquity of man in America.

The influence of the two discussions will be very wholesome
both within and without scientific circles.

The geological papers presented at the meeting of the Brit-
ish Association at Toronto were notable for the wide range of

their themes and their high order of excellence. la, Ce

*

Papers offered at the Detroit meeting of the Geological
Society of America, August 10, 1897:

EDITORIAL 639

“The Granite Mountain Area of Burnet County, Texas.” By FREDERIC
W. Srimonbs, Austin, Texas.

“Exposures near Detroit of Helderberg Limestone and Associated
Gypsum, Salt and Sandstones.” By W. H. SHERZER, Ypsilanti, Mich.

“Notes on the Geology of the Lower Peninsula of Michigan.” By
ALFRED C. LANE, Houghton, Mich.

“The Nomenclature of the Carboniferous Formations of Texas.” By
ROBERT T. HILL, Washington, D. C.

“Stratigraphy and Structure of the Puget Group, Washington.” By
BAILEY WILLIS, Washington, D. C.

‘The Loess as a Land Deposit.”” By J. A. UDDEN, Rock Island, II.

“Tce-transported Bowlders in Coal Seams.”” By EDWARD ORTON, Col-
umbus, O.

‘““Clay veins Vertically Intersecting Coal Measures.” By W. S. GRrEs-
LEY, Erie, Pa.

“Analogy Between Declivities of Land and Submarine Valleys.” By
J. W. SPENCER, Washington, D. C.

“Great Changes of Level in Mexico and the Interoceanic Connections.”
By J. W. SPENCER, Washington, D. C.

sal

Papers offered at the Session of the Geological Section of
the American Association for the Advancement of Science,
Detroit, August 11-13, 1897:

Address of VICE-PRESIDENT WHITE. Subject: ‘‘The Pittsburg Coal
Bed.”

“The Geological Age and Fauna of the Huerfano Basin in Southern
Colorado.” By PROFESSOR HENRY F. OsBporn, Columbia University, New
WionknNh Ys.

“An Account of the Researches relating to the Great Lakes.’’ By Dr.
J. W. SPENCER, Washington, D. C.

“Lake Chicago and the Chicago Outlet.” By FRANK LEVERETT, U. S.
Geological Survey, Denmark, Ia.

“The Lower Abandoned Beaches of Southeastern Michigan.” By
FRANK B, TAYLOR, Fort Wayne, Ind.

“Some Features of the Recent Geology around Detroit.” By FRANK B.
TAYLOR, Fort Wayne, Ind.

“Recent Earth Movement in the Great Lake Region.” By G. K,
GILBERT, U. S. Geological Survey, Washington, D. C.

640 EDITORIAL

“Preglacial Topography and Drainage of Central-Western, New York.”
By PROFESSOR H. L. FAIRCHILD, University of Rochester, Rochester, N. Y.

“A Supplementary Hypothesis respecting the Origin of the American
Loess.” By PROFESSOR T. C. CHAMBERLIN, University of Chicago,
Chicago, III.

“Progress of Hydrographic Investigations of the U. S. Geological Sur-
vey.” By F. H. NEWELL, U. S. Geological Survey, Washington, D. C.

“Stylolites.”” By PROFESSOR T. C. HOPKINS, State College, Centre Co.
Pa.

“A suggestion in regard to the Theory of Volcanoes.’’ By PROFESSOR
WILLIAM NoRTH RIcE, Wesleyan University, Middletown, Conn.

“The Ores and Minerals of Cripple Creek, Colorado.” By H. P. Par-
MALEE, Charlevoix, Mich.

“Observations on the Genus Barrattia.”” By PROFESSOR R. P. WHIT-
FIELD, American Museum Natural History, New York, N. Y.

“Tce Jams and what they Accomplish in Geology.” By Dr. M. A.
VEEDER, Lyons, N. Y.

REVIEWS.

Geological Survey of Canada, Annual Report, Vol. VIII, 1895. By
G. M. Dawson, Director, Ottawa, 1897.

This large volume embracing over a thousand pages contains a
summary report of the work of the geological survey for the year 1896
by Director Dawson; ‘A report on the Country between Athabasca
Lake and Churchill River” by J. Burr Tyrrell and D. B. Dowling; “A
Report on the Geology of a Portion of the Laurentian Area lying to the
North of the Island of Montreal,” by Frank D. Adams, with appendices;
“A Report on Explorations in the Labrador Peninsula along the East
Main, Koksoak, Hamilton, Manicuagan and Portions of other Rivers
in 1892-5,’ by A. P. Low, with biological, petrological and mineralo-
gical appendices ; “‘A Report of the Section of Chemistry and Miner-
alogy,” by G. C. Hoffman ; and of the ‘Section of Mineral Statistics and
Mines,” by E. D. Ingall. The report is accompanied by numerous maps
and by photographic and other illustrations.

The summary by the director possesses the clearness and compre-
hensiveness which characterize all of Dr. Dawson’s general papers. It
gives an admirable synoptical review of the widely extended and varied
enterprises of this great survey. The report of Mr. Tyrrell, and his
assistant, Mr. Dowling, embraces observations made chiefly in the sum-
mer of 1892. They cover Recent, Pleistocene, Cretaceous, Keeweenawan,
Huronian and Laurentian formations, besides topographic, biologic
and other matters. The most important contributions are those which
relate to the Athabasca sandstone, which appears to be the equivalent
of the Keeweenawan of Lake Superior, to the Laurentian gneisses
and associated formations, and to the Pleistocene deposits. These
confirm and extend the previous well-known determinations of Mr. Tyr-
rell in the region west of Hudson Bay.

Dr. Adams’ discussion of the crystalline rocks north of Montreal
shows notable progress in the elucidation of the difficult problems of
that region. Among the most important features are the advances

made in the discrimination of original igneous gneisses from those of
641

642 REVIEWS

metamorphic origin and the additional evidence of the degenerative
granulation of the crystalline rocks as a result of great pressure.

The report of Mr. Low on his remarkable explorations in the
Labrador peninsula contain a vast amount of new and important infor-
mation respecting this heretofore ¢erra incognita. It isimpossible to sat-
isfactorily summarize this. It shows that besides vast areas of gneisses
and granitoid rocks presumably referable to the Laurentian series,
there are extensive belts of later rocks of clastic origin referable to the
Huronian and Cambrian series as interpreted by the Canadian survey.
The rocks classified as Cambrian comprise beds of arkose rock, sand-
stone, chert, dolomite, felsitic shale, argillite and argillaceous shale»
together with gabbro, diabase and fine-grained decomposed traps and
volcanic conglomerates. ‘They appear to embrace those debatable beds
which are referred by some of the United States geologists to pre-Cam-
brian horizons. There is ground to hope that this extended area of
these formations will afford the means for their complete elucidation.
The observations of Mr. Low have made it clear that this great Labra-
dorean area has a complex geological structure and is far from being
properly characterized as simply Laurentian or even Archean.

Mr. Low’s contributions to glacial geology are very important.
They show an outward movement in all directions from the center of
the peninsula. He locates the central névé ground (which is charac-
terized by only slight traces of glacial motion) midway between the
east and west coasts of the peninsula, and between 53° and 55° latitude.
Its southern boundary is in places from 150 to 200 miles north of the
southern water-shed. ‘The report is accompanied by ‘“ Notes on the
Microscopical Structure of some of the Rocks of the Labrador Penin-
Sulla.” loyy IMile, Wi. Ihe leeriniere,

The chemical, mineralogical and statistical reports embrace a large
mass of valuable data. Altogether the report is one of the most
important issued by the survey. THEE

Iowa Geological Survey, Vol. VI. Report on Lead, Zinc, Artesian

Wells, etc. SAMUEL CALVIN, State Geologist, A. G. LEON-

ARD and El.) FE. Bat) Assistant) State Geologistss) (Des
Moines, 1897.

This volume of 487 pages embraces reports on the ‘‘ Lead and Zinc

Deposits of lowa,” by A. G. Leonard; “‘The Sioux Quartzites and Cer-

REVIEWS 643

tain Associated Rocks,” by S. W. Beyer; ‘The Artesian Wells of Iowa,”
by W. H. Norton, and the ‘Relations of the Wisconsin and Kansan
Drift Sheets in Central Iowa, and Related Phenomena,” by H. Foster
Bain.

Mr. Leonard describes the formations which embrace or are con-
tiguous to the lead and zinc deposits, the mode of occurrence of these
deposits, the association of the minerals and the particular forms of the
ores. ‘To these he adds special descriptions of the mines and a dis-
cussion of the origin of the deposits and the general methods of
working them. He makes an important contribution to the general
relationship of the ores in showing that in the Dubuque district zinc
occurs in the higher horizons of the Galena limestone associated with
the lead. This appears to require a modification of the generalization
previously reached in Wisconsin and northwestern Illinois to the effect
that the zinc usually occurs in lower horizons than the lead. ‘The
additional data appear to indicate that in their original deposition in
the strata the zinc and lead were immediately associated with each other,
and that their distribution in the crevices as the result of secondary
action has been dependent upon the conditions of precipitation which
were not uniform in all districts. Mr. Leonard regards the Archean
rocks as the original source of the lead and zinc, having been derived
thence by surface decomposition and carried into the Silurian sea, from
which in turn they were precipitated along with the gathering limestone.
The precipitating agency he thinks was chiefly organic. He discusses
the different theories of the localization of the metallic deposits, and
concludes that on the whole Chamberlin’s theory of oceanic currents
offers the most plausible explanation. He regards the crevices as
chiefly due to flexures of the strata aided by solution. He holds to
the view that the minerals were carried into the crevices by lateral
secretion from the surrounding limestones.

The rocks which Mr. Beyer finds associated with the Sioux quartz-
ites embrace a series of slates and some olivine diabases. The slates
he finds to conformably overlie the quartzite and to be somewhat inter-
bedded with or graduated into the upper quartzitic layers. He regards
the slates as an upward extension of the quartzite formation. In
respect to the thickness of the quartzite formation he favors the lower
estimate of Todd (1500 feet) rather than the higher estimate of Irving
(3000 to 4000 feet), but regards both estimates as doubtful. He con-
firms the view of Irving that the quartzites were formed from siliceous

644 REVIEWS

sandstones by interstitial growth. He favors the view that the quartz-
ites are of early age, the probable equivalents of the Mankato and
Baraboo quartzites.

Professor Norton introduces his discussion by a statement of the
theory of artesian wells and their requisite conditions. He then describes
the conditions of the lowa field, discussing the geological struct-
ure, the area of supply, the reservoir and the conditions of transmission.
This is followed by a description of the wells classified by sections.
Under the head of chemistry of the waters he treats of the mineral
ingredients, of the interpretation of analyses, and of the classification
based on these; and also of the therapeutic, sanitary, and industrial
qualities of the waters. He also touches upon the questions of public
supply, of cost, of purity and of practical matters relative to drilling,
thus giving to the report much popular as well as scientific interest.

The paper of Mr. Bain embraces a special study of the relations of
the two drift sheets found in the vicinity of the capital. After a
careful statement of the history of investigations, he describes, critically,
the Des Moines lobe of the Wisconsin drift as it appears in Pope, Dal-
las, and Guthrie counties, and follows this by a similar critical discus-
sion of the characteristics of the older drift which underlies it, and
occupies the region lying to the south. An important feature of the
paper is the discussion of time ratios as indicated by erosive and other
phenomena. From the computation of special cases selected as being
best suited to the purpose, he reaches the conclusion that the time
ratio between the Wisconsin and the Kansan ranges from 1:10 to 1:15,
being probably nearer the latter than the former. ee

The Iowa survey is to be congratulated upon the excellence of this
report. ibs G.

Geology and Natural Resources of Indiana, Twenty-first Annual
Report. By W. S. BiaTcHLey, State Geologist. Indian-
apolis, 1897.

This report of 718 pages embraces ‘‘An Introduction” and ‘The
Natural Resources of Indiana,” by W. S. Blatchley ; ‘‘The Petroleum
Industry in Indiana,” by the same; ‘The Composition of Indiana
Coals,” by W. A. Noyes; ‘“‘Some Notes on the Black Slate or Genessee
Shale of New Albany,” by Hans Duden; “The Indiana Caves and their
Fauna,” by W. S. Blatchley ; ‘“A Report on the Geology of the Middle

REVIEWS 645

and Upper Silurian Rocks of Clark, Jefferson, Ripley, Jennings and
Southern Decatur Counties,” by August F. Foerste; “‘The Bedford
Odlitic Limestone of Indiana,” by T. C. Hopkins and C. E. Sieben-
thal; “The Report of the State Natural Gas Supervisor,” by J. C.
Leach ; ‘The Report of the State Inspector of Mines,” by Robert
Fisher ; ‘The Report of the State Supervisor of Oils,” by C. F. Hall ;
“The Geology of Vigo County,” by J. T. Scoville ; and ‘“‘ A Catalogue of
the Ferns and Flowering Plants of Vigo County,” by W. S. Blatchley.

The paper of the state geologist on the petroleum industry of
Indiana treats of the geographical and geological distribution of
petroleum, of its origin, and the physical and chemical properties of
the Indiana petroleum. He describes the oil fields by counties, intro-
ducing local details. The report closes with a chapter of a practical
and economical character relating to the choosing of a locality for
operating, the locating, drilling, and shooting of the wells, and their
cost, accompanied by statistics with regard to the Indiana oil pro-
duction.

Mr. Noyes gives the results of the twenty-seven analyses of coals,
with an interpretation of results and a comparison of the coals.

The Notes on the Genessee Shale of New Albany, embrace chemical
analyses, a statement of the previous experiments in utilizing the shale,
and of new methods proposed by Mr. Duden, together with a discus-
sion of the source of the bitumen embraced in the shales. The paper
is accompanied by a description of some of the fossil plants discovered.

The discussion of the Indiana caves by the state geologist
embraces descriptions of eighteen caves located in Owen, Monroe,
Lawrence, Washington, and Crawford counties, accompanied by maps
and photographic illustrations. This is supplemented by a description
of the fauna of the caves, embracing mammals, batrachians, fishes,
insects, and crustaceans, the descriptions being by W. S. Blatchley, J.
M. Aldrich, Mary Murtfeldt, H. F. Wickham, and W. P. Hay.

In his discussion of the geology of the Middle and Upper Silurian
rocks of the southeastern counties of Indiana, Dr. Foerste subdivides
the formations for the purpose of more exact and refined study, as
follows in descending order: The Niagara, into (1) the Louisville
limestone or Utica lime rock, (2) the Waldron shale, (3) the Laurel
limestone or Cliff rock, (4) the Osgood or cystidian beds, divided in
places into (a) the Upper Osgood clay, (4) the Osgood limestone, (c)
the Lower Osgood Clay. The Clinton group he does not subdivide.

646 REVIEWS

The Cincinnati group he divides into (1) the Madison beds and their
northern equivalents, (2) the richly fossiliferous shales and limestones
below the Madison beds, (3) the Gastropod or Marvel Hill beds, and
(4) a great section below not studied. The author enters into detail
in the discussion of these formations and their special features in the
more important localities, in the course of which the fossil contents
receive special attention.

The discussion of the Bedford Odlitic limestone by Hopkins and
Siebenthal is introduced by a discussion of the general geographical
and stratigraphical features of the formation and associated strata.
The body of the report embraces a discussion of the structural and
economic features of the Bedford limestone, a discussion fully war-
ranted by the very extensive use of the limestone as a building
material. The treatment covers the results of both physical and
chemical tests, and embraces the determination of the strength of the
rock in various attitudes, its elasticity, absorption, resistance to fire
and to water, its workability and accessibility. A chapter is devoted
to the commercial features of the formation embracing the quarrying,
handling of the stone, methods of work, machinery used, uses and
adaptabilities of the stone, its transportation facilities, statistics of pro-
duction, etc., which is followed by local descriptions. The discussion
is closed by a classification of odlitic limestones.

The reports of the supervisors of gas, of mines, and of oil, embrace
statistical and economic matter of value to those interested in these
industries.

Dr. Scoville’s ‘“‘Geology of Vigo County”? embraces the general
topography and stratigraphy of the region, the ancient channels which
cross the territory, but are now buried by the glacial deposits, the
Pleistocene glacier of Vigo county, and the recent geology, embracing
the soils and archeology.

The report has the same general form as preceding annual
reports, but is more fully and better illustrated. Cre

Geological Survey of Alabama, Eugene Allen Smith, State Geologist.
Report on the Valley Regions. Part Il, On the Coosa Valley.
By Henry McCattey, Assistant State Geologist.

In this report the physical features of the Coosa Valley Region are
classified into natural divisions, consisting of (1) broad, flat-topped

REVIEWS 647

synclinal mountains bounded by bluffs ; (2) uniform anticlinal valleys
with sharp, well defined limits ; (3) monoclinal mountains with steep
northwest sides and gentle southeast slopes; (4) monoclinal valleys
with ill-defined and irregular northwest limits; (5) flatwoods; (6)
irregular valleys with jagged edges; and (7) chert hills and ridges.
Each of these subdivisions is described and illustrated by local
examples. The geology is introduced by brief reference to the
changes due to denudation, after which the faults of the region, to the
number of sixteen, are named and described. A general description of
the geological formations of the region, ranging from the crystalline
Talladega slates to the Lafayette, follows. The minerals, rocks, and
other substances of special use and interest, are next discussed, and
this is followed in turn by a chapter devoted to the soils, agricultural
features, timber, water power, climate, health, and drainage of the
region. ‘The remainder of the report is occupied with county details,
embracing Etowah, St. Clair, Jefferson, Tuscaloosa, Bibb, Shelby,
Talladega, Calhoun, Cherokee, Clayborn, Coosa, and Chilton counties.
The report is accompanied by maps and illustrated by excellent half
tones.

The economic factor has a very prominent place throughout the
report, and will doubtless render it very helpful in developing the
important resources of the region. Cc:

First Report of the Geological Commission of the Colony of the Cape
of Good Hope. Capetown, 1896.

The Geological Survey of the Colony of the Cape of Good Hope
was recently organized by the appointment of Professor Corstorphine
as geologist, and Arthur W. Rogers and Ernst H. L. Schwarz as
assistant geologists. Considering the limitations of time, of means,
and of personnel, this first report indicates an active prosecution of
the work entrusted to the commission. The report in hand contains
brief contributions on the following subjects: ‘‘Report on the
Laingsburg Coal,”’ by Professor Corstorphine ; ‘“‘Summary of the Work
done in the Southwestern Districts,” by Rogers; ‘Survey of the Beau-
fort West District,” by Schwarz ; ‘‘Summary of the Work done in the
Tulbagh Area and Worcester District,” by Schwarz; ‘‘ Report of the
Subcommittee on Deep Artesian Well Borings,”’ by Stewart, Corstor-
phine, and Saunders ; ‘“‘ Report of a Preliminary Geological Survey of

648 REVIEWS

the Oudtshoorn and Prince Albert Districts made with a view to the
Selection of a Site for a deep Borehole for Artesian Waters,’ by
Corstorphine, and ‘The Cango Cave,” by the same. Geologists will
wish this new survey in a far-off land all possible success. C..

North Carolina and Its Resources. Ussued by the State Board of
Agriculture, Raleigh, 1896.

This is a general work intended to set forth the natural and cultural
interests of the state. The subjects of geological interest are the
topographic sketches illustrated by half tones, the climatic statistics, a
geological map, a list of native minerals, a sketch of the gold, silver,
copper, iron, corundum, mica, talc, monazite, marl, phosphate, coal,
graphite, kaolin, and clay industries, and of the gems and gem stones
of the state. The building stones and road material are also briefly
treated. The work is well illustrated with excellent half tones, and is a
very creditable book. C.

Bulletin of the Minnesota Academy of Natural Sciences, Vol. 1V, No.
1, Part I. Proceedings and Accompanying Papers 13592 to
7594. By C. W. Hatt, Editor. Minneapolis, 1896.

The papers of geological interest are: ‘Notes on the Alpine
Characteristics of the Minnesota Flora of the Coteau des Prairies,”
by E. P. Sheldon; “The St. Peter’s Sandstone,” embracing descrip-
tions of its fauna, including fourteen genera and twenty-eight species,
and a discussion of its origin and correlation, by F. W. Sardeson ;
and ‘The Fauna of the Magnesian Series with Descriptions of its
Fossils,” by F. W. Sardeson. The large additions to the fauna of the
Magnesian and St. Peter’s horizons gives special value to these two
papers. Cc

Proceedings of the Iowa Academy of Sciences for 1596. Vol. IV,
Des Moines, 1897.

The volume contains a portrait of the late Charles Wachsmuth,
accompanied by a memorial by Dr. Charles R. Keyes. The papers of
geological interest are “The State Quarry Limestone,” by Samuel
Calvin; ‘Stages of the Des Moines, or Chief Coal-Bearing Series of

REVIEWS 649

Kansas and Southwest Missouri and their Equivalents in Iowa,” by
Charles R. Keyes; “The Vertical Range of Fossils at Louisiana,”
embracing an extended table, by Charles R. Keyes and R. R. Rowley ;
‘‘ Natural Gas in the Drift of Iowa,’ by A. G. Leonard; “‘ The Results
of Recent Geological Work in Madison County,” by J. L. Tilton;
“The Drift Section at Oelwein,” by Grant E. Finch ; ‘‘ Evidence of
a Sub-Aftonian Till Sheet in Northeastern Iowa,” illustrated by a
section and three full page half tones, by S. W. Beyer; ‘“‘A Pre-Kansan
Peat Bed,” by T. H. MacBride ; ‘‘ A Summary of the Discussion of the
Preceding Papers on the Oelwein Section,” by Professor S. Calvin ;
and ‘“‘ Additional Observations on Surface Deposits in Iowa,” by B.
Shimek. The remaining papers are chiefly biological.

Proceedings of the Davenport Academy of Natural Sciences, Vol. VI,
1889 to 1897. Davenport, 1897.

In this volume of 400 pages the archeological contributions very
notably predominate. Some of these, however, possess geological
interest from their connection with recent deposits. The dignity of
the volume and of the society is lowered by an endorsement of the
ridiculous claims of Captain Glazier, which are unworthy of serious
consideration.

Stone Implements of the Potomac-Chesapeake Tidewater Province.
By Wititram H. Hormes. From fifteenth Annual Report of
the Bureau of Ethnology. J. \W. Powe ., Director. Wash-
ington, D. C., 1897.

This paper, though primarily archeological, possesses much geo-
logical interest because of its bearing upon anthropic geology. It
consists of an elaborate discussion of the manufacturing of flaked
stone implements and of the ancient quarry workshops of the District
of Columbia, in which this manufacture was extensively carried on.
The geological relations of these quarries and of the terranes in which
they occur are accurately and fully set forth by sections, photographs,
and sketches of the clearest possible type. The various stages of
manufacture are fully elucidated by drawings and photographs, so
that every feature of the process is most completely and convincingly
elucidated. The conclusions reached by Professor Holmes are already

650 REVIEWS

familiar to the readers of this magazine. The results of his pro-
longed investigations are here brought together, summed up and
illustrated with a beauty and force which make the paper a monu-
mental contribution to archeology and anthropic geology. (S.

Glacial Observations in the Umanak District, Greenland. By PRo-
FESSOR GrEorGE H. Barton. Report B of the Scientific Work
of the Boston Party on the Sixth Peary Expedition to Greenland.

The paper embraces the observations made by Professor Barton on
the border of the inland ice in the vicinity of Umanak fiord and upon
the large Karajak, Itivdliarsuk and several small valley glaciers. Mr.
Barton found the border of the ice usually nearly vertical to the
height of ten to forty feet. The surface in the vicinity of the margin
was covered with dust holes ranging in diameter from a fraction of an
inch up to at least three feet, with an average depth of about two feet.
Except the dust found in these holes no detritus occurs on the sur-
face of the inland ice. The largest surface stream found flowed in a
channel having a width of twenty feet with a depth of fifteen feet to
the surface of the water which was about five feet in depth. At the
point observed this river was flowing directly toward the interior with
a velocity of three or four miles an hour. The average gradient of
the surface measured on the Karajak glacier was found to be 1 in 52.
Professor Barton observed that the overhanging marginal faces were in
many cases apparently due toashearing motion of the upper layers over
the lower. ‘‘This was indicated quite strongly in one instance, where
a layer projecting slightly beyond the ones above had caught a little
detritus as it rolled down. ‘This same ledge continued from the
slightly inclined face along a portion of the overhanging face, and
here still the detritus remained which had been caught in its descent
before the shearing motion had changed this part of the face to an
overhanging one. A cavern presented a chance for a study of the
material forming the layer upon which the detritus had lodged, and
also for several feet above, showing them to be free from detritus and
consequently that the detritus could only have come from the upper
surface and caught upon the shelf, while the face was inclined, and
that its present overhanging form was due to the shearing motion in
the upper portion of the ice’’—a very important observation.

Professor Barton gives interesting illustrations of the hold of the

REVIEWS 651

ice upon bowlders, and of its methods of behavior in passing over
projecting knobs of rock. He also gives an instructive diagram of
the method of discharge of the ice foot where it protrudes into the
water. Professor Barton believes that the ice ‘once extended over
all this portion of Greenland, passing out beyond the farthest limits
of the present coast line into the open waters of Baffin’s Bay.” He
is not altogether fortunate in his suggestions with reference to Dal-
rymple Rock, a figure of which he introduces for comparison, with the
suggestion that it “presents a marked stoss and lee side, apparently
in their appropriate positions as related to the mainland topography
seen in the distance.’”’ The apparent stoss side faces Baffin’s Bay and
not the inland ice. There is a radical difference between Dalrymple
Rock and the peaks of Ikerasak and of Umanak Island, with which it
is put in comparison, in the fact that the pedestals of the two latter
are distinctly glaciated, showing that they have been typical nunataks,
while the base of Dalrymple Rock shows no signs of glaciation and
belongs in an entirely different category.
The paper is admirably illustrated with half tone photographs.
ex C.

Seventeenth Annual Report of the United States Geological Survey
Eat 1) Director's Report and other papers; Part II, Eco-
nomic Geology and Hydrography; Part III, Mineral
Resources of the United States. CHARLES D. WaALCcoTT,
Director, Washington, D. C., 1896.

This volumnious report embracing three thousand pages of matter
which has just come to hand can only be briefly noticed here. It is
hoped that special reviews of its important papers may be given here-
after. The report opens with the usual statement of the operations of
the survey by the Director. It includes the work done in the years
1895-6 by the nearly forty parties in geology and paleontology, by
the divisions of chemistry and hydrography, by the statisticians, and by
the topographic and publication branches. This is followed in Part I
by papers on “The Magnetic Declination in the United States,” by
Henry Gannett; ‘““A Geological Reconnaissance in Northwestern Ore-
gon,” by J. S. Diller; ‘“ Further Contributions to the Geology of the
Sierra Nevada,” by H.W. Turner ; “A Report on the Coal and Lignite of
Alaska,” by W. H. Dall ; ‘“ The Uintaite (Gilsonite) Deposits of Utah,”

652 REVIEWS

by G. H. Eldridge; ‘“‘The Glacial Brick Clays of Rhode Island and South-
eastern Massachusetts,’ by N.S. Shaler, J. B. Woodworth and C. F.
Marbut; and “ The Faunal Relations of the Eocene and Upper Cre-
taceous on the Pacific Coast,” by T. W. Stanton.

Part II embraces “ The Gold-Quartz Veins of Nevada City and Grass
Valley, California,” by Waldemar Lindgren ; ‘‘ The Geology of Silver
Cliff and the Rosita Hills, Colorado,” by Whitman Cross; ‘“‘ The Mines
of Custer County, Colorado,” by S. F. Emmons ; ‘fA Geological Section
Along the New and Kanawha Rivers in West Virginia,” by M. R. Camp-
bell and W. C. Mendenhall ; ‘‘ The Tennessee Phosphates,” by C. W.
Hayes ; “‘ The Underground Water in the Arkansas Valley in Eastern
Colorado,” by G. K. Gilbert; ‘A Preliminary Report on the Artesian
Waters of a Portion of the Dakotas,” by N. H. Darton; and “ The
Water Resources of Illinois,” by Frank everett, accompanied by an
account of the “‘ Palaeozoic Rocks Explored by Deep Borings at Rock
Island, Lll.,” by J. A. Udden.

Part III embraces the ‘‘Report on the Mineral Resources of the
United States for 1895,” by Dr. David T. Day and associates. This
includes reports on The Iron Ores, by John Birkinbine; on The
Present Condition of the Iron and Steel Industries of the United
States, by James M. Swank; on Copper, Lead and Zinc, by Charles
Kirchoff ; on Chromic Iron, by William Glenn; on Antimony, Coal,
Asphaltum, Soapstone, Abrasive Materials, Sulphur and Pyrites, Gyp-
sum, Salt, Asbestos. Mineral Paints and Barytes, by Edward W.
Parker ; on Manganese, Coke, Petroleum and Natural Gas, by Joseph
D. Weeks; on Stone, by William C. Day; on Clay, by Jefferson Mid-
dleton; on Pottery, by Heinrich Reis; on Portland Cement, by
Spencer B. Newberry ; on American Rock Cement, by Uriah Cum-
mings ; on Precious Stones, by George F. Kunz; on Mineral Waters,
by Alfred C. Peale; and on Gold, Quicksilver, Tin, Aluminium, Nickel,
Cobalt, Platinum, Phosphate Rock, Fluorspar, Chryolite, Mica and
Graphite, by the chief of the division.

Altogether the list of papers is one of unusual range and impor-
tance. Cs

THE

(OUR EOF GEOLOGY

Cenenek NOVEMBER, 1507

A GROUP OF HYPOTHESES BEARING ON CLIMATIC
CEANGES:

WuiLe the atmosphere is the most active of all geological
agencies, it has received the least careful study from geologists.
Its very activity destroys its relics almost as soon as formed
and gives them peculiar evanescence. This has invited the
neglect of geologists laudably prone to concentrate their
attention upon agencies which have left enduring and unequivo-
cal records. The atmospheric element in geological history bids
fair to long remain obscured by elusive factors and uncertain
interpretations. None the less it is an element of supreme
importance and should be persistently attacked until it yields up
its truths. This must be my excuse for offering a paper which,
I am painfully aware, is very speculative in many of its parts.

All our attempts at the solution of climatic problems pro-
ceed on some conscious or wuconscious assumption concerning
the extent and nature of the atmosphere at the stage involved.
These assumptions are too often unconscious and the conclusions
reached command a confidence which might not be reposed in
them if the underlying assumptions were frankly stated. It may
not be unwholesome, therefore, to raise some radical doubts
respecting current assumptions regarding the early stages of the

tRead before the British Association for the Advancement of Science at Toronto,
August 20,1897. For obvious reasons it was necessary to treat the many factors
involved with extreme brevity and hence with some obscurity and much lack of ade-

quate qualification. I have taken the liberty of adding some tables and other matter
Vole NOT 7: 653

654 TC CHA MEE RIETIN

atmosphere and to offer for trial a competitive hypothesis or
group of hypotheses. To admit a competitive hypothesis to the
working list is a concrete form of embodying a doubt respect-
ing existing hypotheses and serves better than any abstract
skepticism to keep alive the sources of doubt. I assume that
the system of multiple working hypotheses is accepted as
furnishing the most wholesome conditions for research, and that
any additional hypothesis not in itself incredible will be wel-
comed.

If we compute the mass of the several constituents of the
present atmosphere, and estimate the rate at which they are
being consumed in alterations of the superficial rocks, we find
that the carbon dioxide will last but a short period unless there be
some source of supply. A group of careful estimates by different
methods gives results ranging from five thousand to eighteen
thousand years’ with a weighted mean of about ten thousand
years. Only the alteration of the crystalline terranes was
admitted to the computations. The estimates assumed the
degradation rates of current geological opinion. Granting these
may be too high, and multiplying the results accordingly, it still
appears that we are confronted by the early exhaustion of a vital
factor of the atmosphere, if there be no compensating source of
supply.

There is, however, an immediate source of compensation.
The ocean is an atmosphere in storage. It is not improbable

and of slightly extending and modifying the treatment on some points, but it still
remains merely synoptic. The treatment of the periodicity of Pleistocene atmospheric
changes is especially incomplete, but this is only a particular case under a general
hypothesis whose value does not necessarily hang upon this individual application.

I desire to add that most of the questions involved in the paper have been dis-
cussed with scientific friends and with the advanced graduate students of my classes
during the past two years, and that I have, received from them much valuable aid.
Computations and quantitative estimates have been made by F. R. Moulton, H. L.
Clarke, A. W. Whitney, J. P. Goode, H. F. Bain, Samuel Weidman, C. F. Tolman, Jr.,
N. M. Fenneman, and C. E. Siebenthal, which I desire to gratefully acknowledge.
The main points of the paper were presented to the Geological Club of the University
of Chicago, October 1896.

™Made by A. W. Whitney, H. Foster Bain, J. P. Goode, Samuel Weidman, C. F.
Tolman, Jr., and the writer.

HYPOTHESES BEARING ON CLIMATIC CHANGES 655

that every portion of it has once been a constituent of the
atmosphere and may be again. In atmospheric studies it must
be recognized as a potential atmosphere. According to the best
data at command, the ocean holds in solution about eighteen
times as much carbon dioxide as the atmosphere. But even this
reserve supply if fully available leaves the perpetuity of atmos-
pheric conditions congenial to life very short, viewed geologically.
This threat of disaster is not, however, a scientific argument,
whatever function it may have in awakening interest and neutral-
izing inherited prejudice.

A broad comparison between the atmosphere of Palzozoic
times and that of Cenozoic times fails, I think, to give proof of
any radical difference in the constitution of the two atmospheres.
The magnolia flora in North Greenland in Tertiary times indi-
cates a scarcely less wide distribution of warm climate than the
life of the same regionin Paleozoic times. Glaciation in northern
Norway announced by Reusch and confirmed by Strahan, in
times apparently just preceding the Paleozoic era, is as sugges-
tive of atmospheric poverty as anything that introduces the Cen-
ozoic times. The signs of glaciation at the close of the Palzo-
zoic erain India, Australia, and South Africa, reaching within 20°
of the equator, indicate a thermal depression even more mar-
velous than that which closed the Cenozoic era. The salt
deposits of the middle latitudes in Paleozoic times, notably
those of Michigan and New York, in areas where the great
basins now overflow voluminously, seem to imply an aridity quite
comparable to anything which has succeeded. The extensive
terranes of hematite-stained rocks, contrasted with the limonite-
stained terranes, while their interpretation is more problematic,
make suggestions of concurrent import.

A comparison of early with later life, stripped of theoretical
presumptions, does not seem to me clearly to imply any great
difference in the content of carbon dioxide. Air-breathing
life, to be sure, has left no certain record earlier than the middle
Palzozoic, but these earliest forms afford no clear proof that
they were determined by non-susceptibility to an excess of carbon

656 He (Oz Cle VANIIESBISSEI ENS

dioxide. The delay in the appearance of land life is sufficiently
assignable to the obstacles to its evolution to make needless a
theoretical appeal to a noxious condition of the atmosphere.

But if we compute the amount of carbon which has been
extracted from the atmosphere in the production of the carbon-
ates and the carbonaceous deposits, and restore this to the
atmosphere, following a time-honored custom, we are led to the
time-honored conception of an exceedingly extensive, dense,
warm and moist atmosphere. The amount of carbon dioxide
represented by the limestones and carbonaceous deposits has
been variously estimated at twelve thousand to one hundred and
fifty thousand times the present content of the atmosphere. My
own estimates lead me to favor figures lying between twenty
thousand and thirty thousand. These estimates do not go back of
the Palaeozoic series and leave an unknown factor to be added for
the pre-Cambrian limestones and carbonaceous deposits. The
amount of carbon extracted from the atmosphere since the
introduction of air-breathing life is probably not less than 8000
or 10,000 times the amount now in the air. This forces the
question whether this large amount of carbon dioxide or any
major part of it was ever in the atmosphere at any one time.

The alternative is to assume that the atmosphere was origi-
nally less ample and has been fed as well as robbed during all
the geological ages, its history being a struggle between enrich-
ment and depletion. In some measure this is an accepted view,
but it is part of the purpose of this paper to show that the way
is open to freer hypothesis in this direction.

The current view of a vast original atmosphere is derived
less perhaps from the computation of material extracted from it
than from theoretical views regarding the origin and early history
of the earth. There has been quite general assent to the nebu-
lar theory of the origin of the earth. Even where dissent from
the gaseous features of this theory has been entertained there
has been acquiescence in the doctrine of the earth’s early molten
condition and all that it implies. If the earth were in a thor-
oughly molten condition, there would seem at first thought but

HVPOTHESES BEARING ON CLIMATIC CHANGES 657

scant ground for any dissent from the inference that the present
hydrosphere was then mainly a part of the atmosphere. It does
not rigorously follow, however, that this was so. Hypothesis may
go so far as to attribute much of the subsequent ocean and
atmosphere to vapors thrown out of the molten magma as it
cooled and to vapors gathered from space since. But I venture
to question the supposed original molten state. While making
no claim to disprove it, 1] doubt whether it rests on sufficiently
solid theoretical grounds to justify the assumptions so unhesita-
tingly built upon it. There is still some ground to doubt the
nebular hypothesis and to entertain some of the various phases
of the meteoroidal hypotheses. The nebular hypothesis corre-
lates a wonderful array of remarkable facts and has gained a
profound hold upon the convictions of the scientific world, yet
some of its great pillars of support have recently weakened or
have fallen away entirely. Of the 5000 known nebule to which
we naturally look for analogy very few, if indeed any, strictly
interpreted, exemplify in a clear and decisive manner the sys-
tematic annular evolution postulated by Laplace. The pho-
tographs of the nebula of Andromeda, that were hailed with such
delight on their first appearance as exemplifying the Laplacean
hypothesis, appear upon more critical study to support it only in
vague and general terms, if indeed they lend it support at all.
The Saturnian rings, the trite source of illustration and analogy,
prove under the test of the spectroscope to be formed of discrete
solid particles, and not of gas, and the investigations of Roche
have put a new phase on their theory. While in their form they
tally with the annular hypothesis they do not support its gas-
eous phase, if indeed they lend it any support at all. But our
chief interest is not in the general theory, but in the special
inferences drawn from it respecting the early stages of the earth.
Let us assume the possible or, if you please, probable truthful-
ness of the nebular hypothesis so far as the separation of an earth-
moon ring from the shrinking sun is concerned. Do the subse-
quent steps commonly postulated logically follow ?

The vast radiating surface of such a ring, its attenuated

658 Th, (O (CLELAN OSI BISIL ION

nature and the extremely high temperature necessary to main-
tain its refractory substances in a volatile condition combine to
suggest its speedy passage from the vaporous to the Saturnian
or discrete solid condition from loss of heat. It seems a severe
tax upon probabilities to suppose that such a ting would remain
in the gaseous condition during the long period of its aggrega-
tion into a spheroidal form.

But a graver source of doubt is found in the high molecular
velocities of the gases under these conditions. Dr. Johnstone
Stoney * and others have attempted to show that the attractive
power of small planets is insufficient to control gases of the
higher molecular velocities, especially aqueous vapor. To this
is attributed the measurable absence of atmospheres on the
satellites and small planets. An endeavor to apply a similar
line of reasoning to the conditions of the early earth leads to
such disquieting results that I may be justified in briefly sketch-
ing it.

Each celestial body has an attractive power sufficient to con-
trol molecules shot away from it at velocities below a certain
limit. At these velocities the discharged molecules pursue ellip-
tical paths and return to the starting point. At the limit of
these velocities they pursue parabolic courses and never return.
Hence arises the expression “‘ parabolic velocity ’’ to indicate the
limital speed at which particles shot away from the body will
not return. The parabolic velocity of the earth at its surface is
about 6.9 miles (1118127) per second. A molecule discharged
from it at that speed or a greater one will not return to it. The
parabolic velocity is but an expression of effective gravity and

t™“ On the Cause of the Absence of Hydrogen from the Earth’s Atmosphere and
of Air and Water from the Moon.”” Royal Dublin Society, 1892. Since this paper
was put in type I have been permitted to see an advanced copy of Dr. Stoney’s later
paper, “Of Atmospheres upon Planets and Satellites,” Trans. Royal Dublin Society,
Vol. VI, Part 13, Oct. 25, 1897, in which the author’s investigations are much more
fully set forth and his conclusions greatly strengthened. He takes account of the
rotary speed of the outer equatorial zone and of westerly winds as projectile aids,
factors which are neglected in this discussion. He also bases a very strong argument

on the absence of helium from the present atmosphere, which on account of its chem-
ical inertness would accumulate if it were not discharged.

HYPOTHESES BEARING ON CLIMATIC CHANGES 659

depends not only upon the amount of the material embraced in
the body, but on its distribution and other conditions. The
parabolic velocity declines with height, as shown in the follow-
ing table prepared for me by Mr. F.. R. Moulton."

IG

TABLE OF THE EARTH’S PARABOLIC VELOCITIES (V,’ )
FOR VARIOUS HEIGHTS ABOVE ITS CENTER (X) THE EFFECTS OF
ROTATION BEING NEGLECTED.*

When ~ (height above center) =o Vy’ =-+

When
When
When

When -
When -

When
When
When
When
When
When
When
When

Wain. oe =
When -
When -
When -

*p'—
2 V

8

2oe— 107422 ft —m19-004 meters.

x
x
aX

Sy I Ay SN) Gn tS GEO AP oR

== + (earth’s radius) Vy’ = 11181.3 meters
yee a> Meters Vea T0072. hae.
= § < ice & ue — OG 32.
S510) Bie V5, ==" QA12.2 ° “
== (10! Vy' = 8914.1 *
ee eet S lee

= iil X ee Vy = 7546.6 *
== 17 3 1OL Vy’ = 6848.4 a
Orato. | O31 3.0) ei
= 25 5 ne? SOAs 8
= ROR eLOo a‘ Vie esas Sh a
= © < 10" Vy’ = 4464.6 ob
==(ele) Sine Lem OAIE ES yf
== 6% ie 2823.7" ot
== 15 X< 10” V5 == 2305.5

5 Se LO ae Ve 2O2. 8, ©
Die KOS I Fae 5047)

7—=06,37'7,377, meters.

Log. 2g = 1.2923447.

Log. r? = 13.6092842.

Log. V 2g r? =7.4508144.

The parabolic velocity is also reduced by the centrifugal com-
The effect of this is shown in the following

ponent of rotation.
tables computed by Mr. Moulton:

t Assistant in Astronomy at the University of Chicago.

- 660

LAG N GLAM TARIEIIN,

Ol,

TABLE OF PARABOLIC VELOCITIES OF THE EARTH (V,)
FOR VARIOUS HEIGHTS ABOVE ITS CENTER (X) WHEN THE PERIOD
OF ROTATION IS 23 HOURS, 56.067 MINUTES.*

Ve, — UU oir2 7 meters

CGIFUG
OMIA. 6
SOuUAO5
SUFmawd
7546.52 ©
6848.31 GG
O31137,0 aan
5047-17
HUG 5oud
4464.39 “
3644.98 ©
BOAR iG
2304.70 we
1260.14 se
HH odh@
229.19 i
.00 Be

When +x (height above center) = o V5 — co
When «+ = ¢ (earth’s radius)

Wienke — F< WO? wanes (( 45349 miles) 7" — 100722405
When + = 8 >< 1@?) % ( Aye 8 )\ Wa" =
When + = Cie GLO eae 5508. 8 Nis
When + = TO << 1@?_ % ( Gar 8 )\ Ws) =
When + = EH. SSe iol as OUT Doligy 8) UA" =
When # = na S<1©2® % ( 10,700 -)/) Va! =
Winein ao = 7 STO? 8 ( 1O@,GO2 ) Yer =
When # = HO) SK TEP. ( RAB OF) IE
Wihenina— DEO aOD fai nei Tai OE )) es
When x = BO >< 1@? ( Ti SAOA ee a) ie —
When x = AO} XeMOr ta saa PST) EN a ee
When x CO STO?) (BO, 8) IAT
Winn ar = TOO Sue? KH ( Awan OC )) Wg =
Winen 2s WSO SK WO (OR ve =
WANE er = FOO) SX Os | (BRO W2@ 2 ) Va
WISIN ge == BFOO) we? F(T Boor) )) 3”
Wiheneai——lOOOODX< soon ass (Opa AAMC). 09 )) 5"
Wien" 3 O44 <a Ocemie ce (18,002,005 “ )) vg" =
ol = ie at aie 7223)" 561007 — Soloed:
Log. V 2¢7? = 7.4508144. Log. = 9.7257080.

ee

TABLE OF PARABOLIC VELOCITIES OF THE EARTH. (v,) FOR VARIOUS
HEIGHTS ABOVE ITS CENTER WHEN

I HOUR, 2

THE ROTATION PERIOD IS
MINUTES, AT WHICH THE CENTRIFUGAL COMPONENT
OF ROTATION EQUALS THE ACCELERATION OF GRAVITY AT THE
EQUATORIAL SURFACE.*

When + (height above center) = 0 V,'

When

When -
When -
When +

4“ —=~yr(earth’s radius)
7 X 10° meters

3 << 16?
OQ < 16"

“cc

in

Vy

+ ©

11171.39 meters
NOOO MOON amie

9970.8
9398.2

ce

ec

HYPOTHESES BEARING ON CLIMATIC CHANGES 661

l1l—continued.

Whenss— 10>¢10° “ 5-8 8O055 es
Witten bee 3O° V5 —— O02 ¢
Wihene— id e< Toe senna me
When — 07 >< bo° V5 — 6822.0 OY
Wihente——z0p~ To" © VZe— 6282-0 e
When ¢ia—a5ec res 5 5005.4 e
When. 300% 10° =“ V5 — OS. 7; uf
When += 40 XI10° “ Vy —) s4o2.4 at
When. — Gor roo * Vy’ = 3552.0 ss
When — too. re® ' < bg = 2668.3 és
Whenw—a5oecro i —— 207 2A as
Whenrm— cope toe “ 07, ae
When —jiogh ator. Wa .0
V 2g 7? 41? x Log. 1 2 gr? = 7.4508144
le = :
Vex z*
t= 1 247 — Sono" Log. HT 6.1914987

7?

The molecular velocities vary with temperature. The fol-
lowing table computed for me by Mr. A. W. Whitney exhibits
these velocities for temperatures ranging from zero to 4000° C.:

TV:

TABLE OF AVERAGE MOLECULAR VELOCITIES FOR VARYING TEMPERA-
TURES, IN CENTIMETERS PER SECOND, STANDARD PRESSURE.

°° 100° 1000" 1250" 500° 2000° 3000° 4000°

He 169611 198257 367258 400428 432243 489410 587282 671029
H,O 56522 66067 122054 133501 144042 163093 195707 223619
CO, 33259 38876 71819 78556 84759 695965 115160 131580
O, 39155 45768 84551 92482 99786 112983 135576 154907
N, 41735 48784 90122 98574 106359 120425 144508 165115

The molecules of a gas of a given temperature have a mean
velocity, but this does not express the actual velocity of the
individual molecules. By their interaction upon one another the
velocities of some are depressed, the limit being zero, and the
velocities of others are increased, the limit being infinity.

662 Ue, Cx CLAN IBIZIRIL IONS

Theoretically both these limits may be reached, but extremely
high velocities are acquired at such distant intervals as to be
negligible. Very considerable exaltations of velocity are how-
ever attained with sufficient frequency to be effective in dis-
charging a large part of the gas under suitable conditions, since
each molecule in succession is liable to acquire a high velocity.
The following table shows the proportion of. molecules that
_ reach or exceed the designated multiples of the average velocity
at any instant :*

We

TABLE SHOWING THE PROPORTION OF MOLECULES WHICH HAVE A
GIVEN NUMBER OF TIMES THE AVERAGE OC. VELOCITY (OR
MORE) AT ANY INSTANT, STANDARD PRESSURE, FOR TEMPERA-
TURES RANGING FROM OC. TO 4000°C.

Froperioniot Times Average o°c. Velocity for different Temperatures

t—ORCe t= 000°C. t—Ir500.C. t= 2000°G, t= 3000°C. t= 4000°C.
Meo LO * I DoD 2.5 2.9 3.5 3.9
to? XK IO =" 2 4.3 5.1 5.8 6.9 7.9
Ae 2X Ome 3 6.5 7.6 8.7 10.4 II.9
Hall SX LO? 4 8.6 10.2 itt 13.9 15.3
On <6 1O— 5 10.8 127, 14.4 173} 19.8
GO << 1O— 6 12.9 15.3 107 08 20.8 B27
38 LO 7 Taso 17.8 20.2 24.2 Dei
MND XX WO 8 7S 20.4 DBr oN DBO Sy] Bil o7/
10) << LO 9 19.4 22.9 25.9 Byie2 35.6
Oa5, < 1O—-8 10) Pit sO) 25.5 28.9 34.6 39.6

The molecules of water vapor at o° C. have an average
velocity of 56522" per sec. The foregoing table shows the

™This table was computed by means of the formulz given by Risteen (“ Molecules
and the Molecular Theory of Matter,” pp. 24-28), which are based on Maxwell’s
determinations. The high velocities assigned to a part of the molecules are mathe-
matical deductions from data not altogether perfect, and are doubtless to be held
with something less of firmness than would be warranted if they were experimental
demonstrations, but in the absence of an available method of experimental demonstra-
tion these deductions may be accepted as the nearest approximation at present
obtainable. A brief non-mathematical statement may be found in Maxwell’s “ Theory
of Heat,” pp. 314-316. The results require some modification for mixed gases and
for special conditions, but this is not thought essential in this general argument.

HVPOTHESES BEARING ON CLIMATIC CHANGES 603

number of times this velocity a given proportion of molecules
attain at any instant when they have certain specified tempera-
tures. For example, the table shows that when the gas is at
o> ©. A7 Xee, ot 47 per cent. of the molecules have a
velocity greater than the average velocity at zero centegrade ;
when the gas is at 1000° C., 47 per cent. of the molecules have
a velocity 2.2 times the average velocity at 0° C.; when at 1500°
C., the same per cent. have 2.5 times the average velocity at
o°C.,etc. To raise the velocity of these molecules to the para-
bolic velocity of the earth the multiplier must be about 19.8
(since 1118127 per sec. is the parabolic velocity of the earth
at the suriacel and miré127 —- 56522 — 19:8, nearly). ‘The table
shows that the proportion of molecules attaining this velocity or
over (taking the figure nearest to 19.8) is as follows:

For 1600" 1.0) << 10,44 HOr 3200088 7-5 6 LOs2°

Porson,” 4.0605 10735 For 4000° 9.7 X 10-%4

RorZzoooee 7-22. lOs7

It now becomes important to ascertain how frequently all
the molecules, on the average, will acquire the parabolic velocity
of the earth. Every time a collision occurs the velocities of the
colliding particles change. The formula for the time required
for complete change will therefore be y,, where JV is the num-
ber of collisions per second at o° C. standard pressure, and Pm
is the proportion of molecules having the parabolic velocity,
given in terms of 0° C. velocity, standard pressure.

The number of collisions per second for 0° C. standard pres-
sure is given by Maxwell as 17,750,000,000 for hydrogen, 7,646,-
000,000 for oxygen, and 9,720,000,000 for carbon dioxide. For
the number of collisions for water vapor I find no authentic esti-
mate, but it probably sustains the same ratio to the collisions of
hydrogen and oxygen that their velocities do to each other,
increased by a certain factor representing the effect of the size
of the molecules. It will here be assumed that the number of
collisions of the molecules of aqueous vapor is 10,000,000,000
pet second ato Co standard pressures lhe results can easily
be modified for any other figure that may be thought nearer the

664 T. C. CHAMBERLIN

truth. The number of collisions also increases with the density
of the gas. In the supposed case of an atmosphere containing
all the water of the globe, the density would perhaps be 300
times the standard density. In the upper regions the density
would be low and ;4, of the standard density may be taken as
a representative of the conditions there. Making the assump-
tion ‘that ithe collisions (of waterivapon are VOL!) perm secs mune
periods required for all the molecules, on an average, to acquire

the parabolic velocity of the earth would be as follows:

At At qty At 300 times
Temperature Standard Pressure Standard Pressure Standard Pressure
1000° 1.7 X 107° years io XX WO? Ears 5.7 X 1073 years
I500° 8) < UO! TODS TOM AS Beis SM noe
2000° AKI «& AK Ie iol KTE® &
3000° 33 years 3300 years 4o days
4000° 1030 seconds 28.5 hours 3.4 seconds

Under the current hypothesis of a molten earth derived from
a gaseous one the temperature of the atmosphere would probably
exceed 4ooo C. during the stages of condensation of the
refractory material of the earth from the form of a gas to the
form of a liquid. From this fervid stage the temperature would
fall to 2000° C., or below before the crust would begin to form
and the external louid condition cease. The temperatures of a
liquid earth may therefore be assumed to range from 4000° C.
to 2000° C. or below, and the figures of the preceding table may
be interpreted on this basis.

If the question were simply the acquisition of molecular
velocities at the surface of the liquid mass greater than the
parabolic velocity of the earth at that point within an available
length of time, it would appear that the retention of the water
vapor would be put in serious jeopardy during the hotter stages,
but that it might survive the cooler ones in large part if it
reached them, unless they were very prolonged. But there are
other considerations to be taken into account. Under the most
favorable conditions only a part of the molecules which attain a
speed beyond the limital velocity of the earth’s control would

HYPOTHESES BEARING ON CLIMATIC CHANGES 665

escape because they would not be projected away from the earth.
Besides, the escape of molecules projected outwards is seriously
limited by the interference of thé particles above. This inter-
ference is practically prohibitory for the molecules in the base
of the atmosphere. The problem, therefore, involves the extent
to which the high velocities of the lower hot atmosphere would
be communicated to the upper atmosphere whence escape would
be possible. The interpretation of this is beset with great diffi-
culties. The molecular velocities of the higher parts of an
atmosphere surrounding a molten earth involve factors which
cannot be safely estimated from the phenomena of a cold earth.
It must of course be assumed that the molecular velocities of
the molecules of the rising air would be lowered in proportion to
the work done by them or the energy lost, but in convectional
movements certain parts of the air are recipients of motion
rather than generators of it, and do not lose the energy their
movements might seem to imply. It is probable that the inter-
change of lower and upper air about a molten earth would be
extremely violent. It is not unlikely that explosive convection
like that of the sun would be the customary mode of action. If
hot bodies of vapor were shot violently into the outer limits of
the atmosphere, molecular discharge would seem to be probable
if not inevitable, whatever might be true of the more quiet mode
of action. Besides this the current nebular hypothesis appar-
ently involves the passage of even the outer atmosphere through
very hot stages during the early period when the refractory
gases of the now solid material were condensing and separating
themselves from the atmospheric gases.

The case in this form seems at present indeterminate. There
is an apparent probability that a large loss would be suffered
while the temperatures ranged from 3000° to 4000°. At the
same time there is a possibility that a residue would remain if
the period of this high temperature were not prolonged, and a
probability that a large part of the atmosphere would be retained
if it survived until the temperatures were near the melting point
of rock.

5

666 fT. C. CHAMBERLIN

The considerations that grow out of altitude above the sur-
face which reduces the parabolic velocity have been neglected
thus far. These are not very important in a shallow atmos-
phere as may be seen by reference to the tables previously
given, but they might be consequential in an exceedingly
extended atmosphere. While it would be hazardous to esti-
mate the height of a superheated atmosphere embracing the
whole present hydrosphere, it seems not improbable that its
outer portion would be appreciably affected by the reduction
of the parabolic velocity due to its high altitude.

To this is to be added also the effect of the high rotation
which the earth is assumed to have had. Inthe supposed dis-
charge of the moon under either the nebular or fission hypothesis
the attraction of the earth in the equatorial zone must have been
nearly or quite neutralized by the centrifugal effect of rotation.
This must have greatly promoted the expansion of the atmos-
phere in that zone and correspondingly reduced the earth’s power
to control its outer portion, indeed it is difficult to see how the
moon could have separated from the earth without carrying away
the atmosphere, unless indeed the separation took place while
the material of both bodies was in a perfect gaseous condition
and the atmospheric constituents were diffused throughout the
entire gaseous mass. But even in this case the subsequent con-
traction of the earth should apparently have accelerated its rota-
tion to such an extent that the retention of the outer equatorial
atmosphere would be put in jeopardy.

There is still another consideration whose importance may
possibly be decisive—the dissociation of water. Dr. Stoney
has maintained that even under present conditions the earth is
incompetent to retain hydrogen. This conclusion is in harmony
with the fact that hydrogen does not permanently exist in
the atmosphere, though this absence may be otherwise explained.*
At 1000° C. all molecules of hydrogen would acquire the para-
bolic velocity of the earth some hundreds of thousands of times

‘In his last paper, referred to in a previous footnote, the weakness of the argu-
ment from the absence of hydrogen owing to the ease with which it may combine

HVPOTHESES BEARING ON CLIMATIC CHANGES 667

per second. Now the temperatures of the supposed molten
earth reached and probably much exceeded the temperatures of
effective dissociation of water vapor. The dissociation is prob-
ably due to violent impact of molecules of high velocities. It
probably takes place in some degree even at moderate temper-
atures." The proportion of dissociated molecules greatly
increases with temperature until the dissociation so far exceeds
the recombination that it may be said to be nearly or quite com-
plete. Authorities differ as to the temperature of effective dis-
sociation. The estimates commonly given lie in the lower half
of the range of temperatures above assigned to the molten stage
of the earth. If, therefore, the temperatures of the molten globe
ranged as high as the current hypothesis seems to require, the
dissociation of the aqueous vapor would seem to be inevitable
and the loss of hydrogen would be endangered notwithstanding
its disposition to recombine.

If the retention of the atmosphere be put in jeopardy by the
earth’s temperatures ina supposed liquid state much more would
it be endangered if the temperatures were those of volatilization
of the refractory material of the earth, as assumed by the
Laplacean hypothesis, for not only would the molecular veloci-
ties be enormously increased, but the extension of the mass
would push its exterior portions out into the regions of low
parabolic velocity.

If the mass be still further dispersed into the vast gaseous
ring of the Laplacean hypothesis the argument from molecular
velocities is immeasurably strengthened, for not only must the
temperatures requisite to the retention of the refractory sub-
stances of the earth in the attenuated condition of such a gaseous
ring be exceedingly high, but the parabolic velocity of the body
with the free oxygen of the air is in a large measure covered by resting the argument
chiefly on the absence of helium, which is chemically very inert. As helium is given
off slowly by hot springs, it is urged that in the vast lapse of the geological ages it
should have accumulated to an appreciable quantity if it had not escaped. As it has
twice the molecular mass of hydrogen it is held that the minimum speed of control”
at existing temperatures lies below the molecular velocities of gases which are twice

as heavy atomically as hydrogen.
* RISTEEN, Molecules and Molecular Theory, pp. 50-51.

668 Wey (Go (CLAANIM SS PISSLION.

in such an extremely distributive form would be exceedingly
low. It would seem, therefore, that unless the argument from
molecular velocities is radically and grievously at fault the
hypothesis of a gaseous earth-moon ring is untenable unless a
degree of tenuity be assumed which separates the molecules
beyond the limits of effective kinetic relations. Inthis case the
argument from rapid cooling becomes peculiarly strong and
seems to leave no alternative but the conversion of the refractory
matter of the ring into the discrete solid condition.

Impressed by these considerations and following what seem
to be the legitimate implications of molecular studies, I have vent-
ured for myself to place the atmospheric inferences from the
supposed gaseous and molten conditions of the primitive earth
in the list of uncertain deductions and to add an alternative
hypothesis to my working list.

But occasion for doubt concerning an early molten earth and
its vast atmosphere is not limited to this line of approach. On
other grounds we cannot fail to recognize that some form of the
meteoroidal hypotheses of the origin of the earth is entitled to
be reckoned among the possibilities. Whether an accretion of
meteoroidal matter would give rise to a molten earth or not
would depend upon the rapidity and violence of the infall. If
the intervals between falls were sufficient the heat would be lost
concurrently. A relatively cold earth is theoretically as possible
as a hot one until it is shown that the aggregation must be rapid.
Even following the general line of the nebular hypothesis a cold
earth is hypothetically possible. We have found reason for
thinking that the earth-moon ring, if formed, would probably
become cooled to discrete solid particles while still in the ring
form. Now it does not appear that there are any conditions
inherent in such a ring that tend toward sudden concentration
into a spheroidal body. Quite on the other hand, the problem
presented by such a ring is to find agencies which will lead to
its concentration at all. Just how the concentration would take
place is an unsolved question.’ But two things seem certain; first,

*I have ventured to speculate a little upon this, though beyond the province of a

HYPOTHESES BEARING ON CLIMATIC CHANGES 669

the process would be slow; the individual conjunctions more or
less distant in time, and the heat generated by one impact so far
forth lost before another took place; second, the conjunctions
would not be opposing collisions but overtakes in which both
bodies were moving at nearly the same speed, and the heat of
conjunction hence relatively small. It would appear, therefore,
that the aggregation might take place without the development
at any one time of a general high temperature. The present
accretions of the earth show us that growth is possible without
notable increase of temperature. Following the general line of
the nebular hypothesis, therefore, it 1s possible to suppose the
earth to have been affected by relatively low surface temperatures
at all stages of its growth. By changing our assumptions as to
the rate and vigor of accretion we can correspondingly change
our conclusions respecting the earth’s temperature. The range

geologist, because it involves a supposed objection to meteoroidal aggregation. Ina
solid rotating ring the outer part moves faster than the inner and if broken and con-
densed to the globular form the rotation must be direct. But in a ring of planetoids
the inner members move faster than the outer and if the several concentric orbits be
symmetrically drawn together so that the inner planetoids uniformly or usually collide
with the inner sides of the outer planetoids retrograde rotation follows. But this is
inconsistent with the facts of the solar system except in the case of Uranus and
Neptune (Cf. Faye, sur !’Origine du Monde, 1896, pp. 165, 270-281). But it seems
improbable that this would be the mode of union except in the case of the outer planets,
for the mutual gravitation of minute planetoidsis very slight and expresses itself chiefly
in perturbations under such conditions (see On the Stability of Motion of Saturn’s
Rings, Scientific Papers of James Clerk Maxwell, Vol. I, pp. 288-376), while the disturb-
ing influence of the great planets is appreciable, as the ellipticity of the orbits of the
planets testify. If the orbits of the particles or planetoids of the supposed earth-
moon ring were at first nearly circular and concentric the conjoined attractions of
the outer planets would render them elliptical. But the line of their apsides would
not be concordant and would be subject to subsequent shifting in a more or less
non-concordant fashion. It is therefore conceived that they would be brought to
cross each other and that this would lead to collisions. Now an outer orbit could
only cross an inner one by a more or less perihelion portion of it coming into coinci-
dence with a more or less aphelion portion of the inner one. But the perihelion
movement of a body in an outer orbit is greater than the coincident aphelion move-
ment of a body in an inner orbit. Hence on the average the outer body in collision
will have the greater speed and the consequent rotation wiil be direct. As this
reasoning applies to the inner planets and not to the outer, and as the inner planets
have direct rotations while the outer probably have retrograde rotations, it has at
least the merit of coincidence with the facts.

‘

670 T. C. CHAMBERLIN

of rational hypothesis seems therefore to be wide. It is herein
urged that it is wholesome at present to recognize this wide
range in its fullest amplitude.

But if we question current conceptions we should present
alternatives which account for the atmosphere and for internal
heat. Let us therefore hastily follow the hypothetical growth
of a planet built up by the slow aggregation of small bodies
which join it at low velocities and develop a minimum heat.
Let the case be purposely made rather extreme to develop —
sharply the difficulties springing from it. Let the infalling par-
ticles be small and their rate such as not to generate a high
surface temperature. The growth of such a body up to the size of
the moon may be taken as an hypothesis of lunar history and
the phenomena of the moon may serve as a check upon it. The
moon may, however, have originated by fission even though the
earth were built up by accretions. In the early stages of growth
the gravity being low the aggregation may be supposed to have
remained uncondensed. Volcanic aggregations of bombs, cinders
and ashes are perhaps the nearest terrestrial analogues. The
ingathering particles obviously carried with them so much of
the atmospheric material as was entrapped or occluded within
them in their solidification, or was absorbed into their pores or
adhered to their surfaces. Judging from meteorites the amount
of this might have been large. Gaseous molecules moving as
independent bodies may have joined the aggregation and become
absorbed in its porous body, but they would not have been col-
lected into an appreciable atmospheric envelope until the body
passed the size of the moon if the molecular considerations
urged earlier in this paper hold good, though an atmospheric
envelope would not have been entirely absent. As the mass
grew the central pressure increased and condensation produced
heat at the center proportional to the work done. I find the
explanation of internal heat chiefly in this self-condensation, it
being essentially the application of the Helmholtz solar theory
to a solid body. Tidal kneading and chemical action doubtless
added their contributions. When the growing mass reached the

HYPOTHESES BEARING ON CLIMATIC CHANGES 671

size of the moon a definite problem was presented of which the
present moon stands as a possible representative and invites
computation. If in its loose state of aggregation the mass had
a specific gravity of 2. and if it shrank by self-condensation to
3.4, the average specific gravity of the moon, the possible heat gen-
erated by the gravitative fall would have equaled 3900° C. for the
whole mass, the specific heat being assumed to be .2, which is
very prudent. I owe the computation to Mr. Moulton. For
convenience of computation the condensation was assumed to be
uniform and the distribution of heat uniform. The original
distribution of internal heat would perhaps have varied with the
square root of the pressure, according to Laplace’s formula.
As the computed temperature is more than twice the melting
temperature of average rock not under pressure it seems ample
for all igneous phenomena indicated on the moon with a large
residue for secular loss.

Assuming that the exterior temperature remained below zero
during the pre-atmospheric stages of growth, the hypothetical
structure of the planet when it reached the size of the moon may
be pictured as embracing (1) a dense central portion raised to a
high temperature by compression, giving a potentiality of lique-
faction under relief of pressure; (2) a zone of declining temper-
ature and less compressed structure, graduating toward a porous
condition, and (3) at the surface the still unconsolidated open
aggregation. The low average specific gravity of the moon
(3.4) encourages the belief that the outer porous zone was deep
and open. The notion is entertained that the central heat and
compression would lead to the expulsion of a part of the cen-
trally entrapped gases and vapors, and that these would be
driven outward into the exterior porous portion, which having a
low temperature, like that of the moon today, condensed the
aqueous vapor in the spaces of the open texture and the whole
became bound together more or less completely with a matrix
of frost and ice. It is assumed that the internal condensation
would be attended by readjustments of matter of the nature of
diffusions, differentiations and concentrations, and that there

672 Me (Cy CLELANIMETEIRICION,

would be deformations and igneous extrusions as on the earth
today. Perhaps the reduction of metallic oxides and the working
of the slag toward the surface may have been an incident of the
process. Now whenever igneous extrusions invaded the zone of
congealed vapor conditions would be afforded favorable for the
generation of great quantities of steam temporarily restrained by
the overlying fragmental mass and facily subject to explosive
discharge. The peculiar constitution of such a body invites the
notion of exceptionally explosive eruptions, as’ do also the
extraordinary pits of the moon. Asa matter of fact the sug-
gestion arose from studying the pits and not from the peculiar
constitution of the body to which the speculation had led.
These remarkable cavities seem to be the close analogues of
the few explosive craters which the surface of the earth pre-
sents.

The pre-atmospheric stage of the evolution would obviously
cease when the growing earth acquired a size sufficient to measur-
ably control its exhaled and ingathered gases. A certain meas-
ure of control was incidental to all stages, for even a small
planetoid has some power to control gases of very low initial
velocity if it continues at low temperatures. At the size of the
moon gases of much more than the average molecular velocity
Of those of the earth at oc ©: could be held it them velocires
were not exalted by interaction. This exaltation would become
ineffective when the gases became extremely rare and the sur-
face very cold. The molecular argument does not therefore affirm
the total absence of an atmosphere on the moon, but rather on
the contrary its scanty presence. An effective control would
perhaps begin to be gained by the growing planet when the size
of Mercury or thereabout was attained. After this the vapors
and gases of lower molecular velocity would collect upon the
surface and initiate the appreciable history of the external atmos-
phere. Whensoever the accretions of this atmosphere acquired
the power of retaining the heat of the sun to such a degree as
to give a surface temperature above the freezing point, the inau-
guration of the hydrosphere would take place and with its pro-

HVPOTHESES BEARING ON CLIMATIC CHANGES 673

gressive development the familiar phenomena due to superficial
waters would appear. The surface would soon lose its extremely
fragmentary condition and take on the terrestrial form; the sub-
terranean frozen zone would disappear and the vulcanism assume
the terrestrial type.

This hypothesis, it will be observed, departs radically from
the familiar view in that it initiates the atmospheric history by
a tenuous envelope which continued to slowly increase. By the
hypothesis, as thus far sketched, the atmosphere was derived
from the interior. After the earth reached the requisite size the
collection of wandering gases would supplement it. The compe-
tency of this external source is almost wholly a matter of con-
jecture and its vague possibilities need not be discussed here.
It need only be remarked that the hypothesis of molecular dis-
charge involves the peopling of space with flying molecules.

The measure of competency of the interior to supply an
atmosphere is obviously a critical question. Unfortunately we
are almost entirely without specific quantitative data bearing on
the subject. We know that there is not a little atmospheric mate-
rial in the interior as demonstrated in volcanic action and in the
content of the minute pores of the hypogene rocks, but we do
not know how far this was derived from the surface. If the
moon never has had an appreciable external atmosphere its
explosive eruptions were not due to surface infiltration and the
implications of its numerous and vast craters are very sug-
gestive. We can also draw inferences from meteorites which

/ sometimes contain several times their volume of gases, as well
as solid matter susceptible of conversion into atmospheric con-
stituents. But at best we can only form very vague quantitative
notions. On the other hand, we are liable to overestimate the
amount required. The atmosphere and the ocean combined are
little more than ;,),, of the mass of the earth. To be com-
petent, the ingathered matter need therefore only contain about
sy Of I per cent. of atmospheric and aqueous material, plus an
added factor for what may have been lost and what still remains
in the interior. This percentage does not seem large enough

674 T. C. CHAMBERLIN

to render the hypothesis improbable in the present state of
knowledge.

The competency of self compression to generate the internal
heat of the earth is also a critical question already touched upon.
Estimates made by different methods seem to give an ample
supply. Thesafest seemingly is that of Mr. Moulton who simply
computed the energy that would be required to lft the matter
of a homogeneous earth of 5.6 sp. gr. against gravity alone to
such a height as to give the whole a uniform specific gravity of
3.5. This is more than the present specific gravity of the moon
and is obviously extremely conservative. The fall of this matter
was found capable of raising the whole mass (specific heat being
taken at the over-figure of .2), to 6560° C., or about four times
the average melting, pointyot =rock) at) the ‘sunacesa) tacme
original specific gravity be taken at 2. on a gross average, which
seems much more probable than 3.5, when the supposed loose
state of aggregation is taken into account, the possible tempera-
ture, if all the potential energy were converted into heat and
retained, would exceed 13,000°. A portion of the energy might
take other forms than heat and a portion would be lost concur-
rently, but as the heat was generated in the interior and must
have been conducted to the surface very slowly, the secular loss
must have been of the conservative order. On the other hand,
tidal friction and possibly chemical action would add to the
interior heat and more or less offset these sources of loss. On
the whole, therefore, self condensation seems a competent source
of internal heat unless the rate of aggregation was excessively
slow.

Although aside from my central purpose, it may be remarked
that the recognition of a progressive self-condensation of the
earth from a loose aggregation to a more dense one by a pro-
longed and still incomplete process presumes a degree and
quality of shrinkage peculiarly suited to explain the inequalities
of the earth’s surface. An explanation must be found not only
for the mountainous wrinklings of the crust in post-Cambrian
times and the great crumplings and crushings of the Archean

HYPOTHESES BEARING ON CLIMATIC CHANGES 675

ages, so much neglected, but also for the great continental eleva-
tions and their superposed plateaus, and the deep oceanic depres-
sions with their abyssmal anti-plateaus—— phenomena with which
current hypotheses have struggled so unsatisfactorily. It is also
necessary to find an explanation for the unequal distribution of
densities which have been partially revealed by gravity observa-
tions, but which are more broadly suggested by the unsym-
metrical aggregation of the hydrosphere. The total shrinkage
of the earth from first to last, under the hypothesis here pro-
posed, would perhaps be sufficient to reduce its volume as much
as one-half or even more, this, of course, depending on the
original density. While the most of this contraction would
antedate known geological history, the process can scarcely be
supposed to have been complete in pre-Cambrian times, or even
to be complete now. A part of the condensation must, there-
fore, quite certainly have fallen within geological history, and a
part must remain yet to be accomplished, for, in addition to the
retardation of the process of condensation caused by the heat
generated, by the rigidity of the outer rocks and by the rapid
rotation of the sphere, the maximum condensation of the mass
could only be attained by means of a general rearrangement of
the heterogeneous material of the meteor-built globe through
the agency of diffusion, segregation, re-combination, re-crystal-
lization and other processes which aid in giving a maximum
compactness to mixed material. This internal readjustment
must necessarily have been a slow process if the globe has been
solid throughout its entire history, and must doubtless be yet
incomplete. This progressive rearrangement of internal material
_adds a special agency of contraction to loss of heat, change of
rotation and similar processes now recognized and which would
act under this hypothesis essentially as under the current view.

If we make the plausible assumption that a slow process of
diffusion, differentiation, concentration and gravitative readjust-
ment has been in progress throughout the whole history and is
yet active, and that matter has crept up from the hot compressed
center into the superficial parts where relief of pressure would

676 T. C. CHAMBERLIN

cause liquidity, we seem to have an equally facile basis for the
explanation of molten extravasations.

It may also be remarked that the acquisition of an atmosphere
and hydrosphere at a moderate temperature when the growing
earth reached a medial size introduced conditions congenial to
life at a stage sufficiently anterior to the Cambrian period to
satisfy the most strenuous demands of theoretical biology. Most
of the restrictive arguments of Lord Kelvin and others lose their
application under this hypothesis.

Returning to the atmospheric problem, it is to be remarked
that the assumption of a limited early atmosphere may be enter-
tained quite apart from the foregoing accretion hypothesis.
Under the current hypotheses of the separation of the moon, ©
whether by the annular mode of Laplace or the fission mode of
George Darwin, great rotary speed and high temperature are
assumed as necessary or probable conditions. We have seen
that these seem to put the retention of the atmosphere in jeop-
ardy. The balance of theoretical probabilities, as I now see
them, favors the presumption that the atmosphere would have
been greatly reduced under these conditions. There does not
therefore seem to me any firm ground, even on current theories
of the earth’s origin, for insisting on the acceptance of the doc-
trine of a vast primitive atmosphere, as the great reservoir from
which subsequent abstractions have been chiefly taken. I think
we are free, therefore, toassume just such a Paleozoic atmosphere
as the life and deposits of that time seem to imply, interpreted
by the phenomena of today. Such an interpretation seems to me
to indicate conditions not radically dissimilar to those of the
recent geological ages; warm climates in high latitudes at
times, colder climates in lower latitudes at times, moisture at.
times, aridity at times, and like oscillations. This view carries
with it the necessary corollary that the atmosphere has been
supplied by accessions in some near proportion to its losses.
That additions have been made to the atmosphere of vital
importance is a familiar doctrine, but it is here pressed to an
unfamiliar degree.

HVPOTHESES BEARING ON CLIMATIC CHANGES 677

If we push the doctrine thus far it is important to assign
J causes for the fluctuations of supply and exhaustion of the
atmosphere, to give the doctrine a working form and to devise
means of putting it to the test. Concerning external sources of
enrichment we know so little that we can scarcely say that there
is a leaning of probabilities either toward or against practical
uniformity. The internal supplies were probably correlated in
- some measure with igneous extravasations— not that such extrav-
asations were the sole mode of liberating gases, but that other
modes probably worked concurrently with them. The escape
of gases was probably also correlated with crustal move-
ments, especially those that compromised the continuity of the
surface rocks, particularly the profound crushings which mining
and the microscopic study of the hypogene rocks reveal. In
these phenomena therefore, may be found a rational basis for
inferring the times of probable atmospheric enrichment. For-
mulated as a proposition, it may be postulated that special
enrichment coincided with special igneous extravasation and
crustal disruption, taking the earth as awhole. The supply may
be assumed to have been uniform in so far as these and other
means of liberation were on the average uniform.

The phases of depletion are susceptible of more satisfactory
treatment. In the first place, the depletion was differential.
The loss of nitrogen was doubtless slight, because of its chem-
ical inertness, and hence, though the supply may have been
small, the nitrogen grew to ultimate dominance. The depletion
of oxygen through the alteration of surface rocks was notable,
but less than that of carbon dioxide. As a result the latter
became the minimum factor of the atmosphere and the critical one.
The enormous reserve supplies of water rendered its consump-
tion inconsequential.

In the second place, the depletion was conditioned upon the
exposure of the surface rocks to atmospheric alteration. This
in turn was conditioned upon topography. In stages of ele-
vation the water table of the land is depressed and the zone
of atmospheric penetration is deepened. At the same time the -

«

678 Le Cx (CLLANEBIER LTV:

zone of effective penetration of aerated water below this is also
deepened. Hence the alteration of the rocks is promoted. In
stages of low elevation — stages of baseleveling, for example —
the zone of atmospheric penetration is shallow and rock altera-
tion proceeds slowly. From this may be deduced the law that
during stages of depression or baseleveling, depletion pro-
ceeded slowly. The aggregate surface must, of course, be con-
sidered.

To apply this law, let us assume for the moment, a uniform
supply equal to the average rate of exhaustion. With the inau-
guration of any great epoch of general uplift there would begin
an era of relatively rapid atmospheric exhaustion, which would
proceed continuously during such elevated stage and might result
in notable atmospheric impoverishment, as the computations cited
early in this paper show. As the cutting down of the surface
approached baselevel, the depletion would be retarded and, the
supply continuing the same by hypothesis, the rate of exhaus-
tion would fall below that of supply and an epoch of enrichment
begin. A second elevation would re-inaugurate the depletion,
and so oscillations of enrichment and impoverishment would fol-
low the general oscillations of the land surface.t. Applying this
law by itself, atmospheric poverty should follow at some distance
the stages of general elevation, and, on the other hand, atmos-
pheric enrichment should follow at some distance the stages of
baseleveling or depression.

But the assumption of a uniform average supply needs revi-
sion. In the main the igneous extrusions and crustal disrup-
tions that are presumed to favor gaseous emanation probably
fell in with the initiation of the elevated stages that favored
depletion. Ina general way the curves of supply and of deple-
tion ran together in geological history and gave a measurably

‘More strictly, the oscillations of that part of the land surface whose rocks con-
sumed the atmosphere by their alteration — in general terms, the crystalline areas.
Periodic general elevations followed by general baselevelings or some notable
approach to baselevelings, are here assumed. It would be obligatory to state the

grounds for this in an ampler discussion, but the all too narrow limits of this paper
make this impracticable.

HYPOTHESES BEARING ON CLIMATIC CHANGES 679

constant atmosphere, but their occasional failures to run in
consonance are herein assigned as possible causes of exceptional
climatic episodes, for it is almost axiomatic to say that climatic
changes would attend changes in the constitution of the atmos-
phere. I assume that atmospheric poverty, especially in the
critical item of carbon dioxide, is correlated with low tempera-
ture, as urged by Tyndall and others.

It is impossible here to attempt to apply the doctrine in
detail to geological history. But it may be noted in passing
that the Pleistocene glaciation followed at a notable interval the
formation of the great plateaus and epeirogenic uplifts of late
Tertiary times. The glaciation of India, Australia and South
Africa occurred about the the time of the crustal revolutions
that marked the close of the Paleozoic era. The uncertainty
of the homotaxis of the strata involved makes a precise cor-
relation at present impossible. The glaciation perhaps came too
early to fitthe hypothesis.t. Here, at least, is an excellent chance
to put it to trial. Allother hypotheses of glaciation have fared
badly when brought to the supremely severe test of the ancient
oriental low-latitude glaciation, and if this hypothesis shall fol-
low them to the junk shop of broken down theories it will find
an already beaten path. The glaciation of northern Norway
as determined by Reusch and Strahan succeeds the pre-Cam-
brian stage of elevation, but in what precise relations is not
known.

The great extensions of warm climate to the high north
appear to be associated with baseleveling periods in a general
way ; but whether ina specific connection of sufficiently declared
nature to indicate the relation of cause and effect remains to be
determined.

Another source of atmospheric depletion needs recognition.
Dr. S. W. Johnston is responsible for the opinion that the entire
carbon dioxide of the atmosphere would be removed by the pres-
ent annual growth of vegetation if there were no return through
decomposition and animal life provided it were continued uni-

‘It may fall under the organic factor of the hypothesis mentioned later.

680 The (C3 (CLEANSE STRILION,

formly for one hundred years.t. Animal life, however, makes
such nearly complete returns that the permanent loss is usually
regarded as negligible. Nevertheless it is something. In cer-
tain stages of the world’s history it has been important, as the
coal beds testify. The loss in the Carboniferous age has been
held sufficient to remove a noxious excess from the early atmos-
phere. On the same basis it might be held to cause serious deple-
tion in the absence of the excess. It is necessary at least to
consider whether, under the theory of a limited early atmosphere,
conditions which restrain the animal factor of the organic cycle
may not so far impoverish the air as to seriously affect climate.
But this cannot be entered upon here. ‘The organic cycle is very
sensitive and very rapid in its action. It would naturally be
greatly influenced by the topographic conditions which were
concerned in the supply and exhaustion of the atmosphere, and
lend to them either its concurrent or its counteracting influ-
ences.

It is now a little more than fifty years since Tyndall sug-
gested that the periods of terrestrial glaciation might be depend-
ent upon the carbon dioxide of the atmosphere whose peculiar
competence to retain solar heat he had demonstrated. The sug-
gestion of the origin of glaciation through the depletion of this
atmospheric constituent is, therefore, not at all new. It has
been entertained by others than Tyndall. If it has failed to
find much acceptance this has perhaps been partly from a
doubt as to its adequacy and partly from the lack of any
definitely assignable cause for the requisite intermittent deple-
tion. Dr. Arrhenius has recently contributed to the subject
a most important discussion bearing especially upon the
former point.? By an elaborate mathematical analysis of data
derived from Langley’s experiments he has endeavored to
ascertain what degree of depletion of the carbon dioxide of the
present atmosphere would bring on the conditions of Pleisto-
cene glaciation, and, on the other hand, what degree of enrich-

t How Crops Feed, p. 47.

2Svente Arrhenius, Phil. Mag. S.5, Vol. XLI, No. 251, April, 1896, pp. 237-279.

HYPOTHESES BEARING ON CLIMATIC CHANGES 681

ment would produce the warm climate of the Tertiary. He
arrives at the conclusion that the removal of 38 to 45 per cent.
of the present carbon dioxide would bring on glaciation and that
an increase of 2.5 or 3 times its value would produce the mild
temperatures of the Tertiary times. He quotes the opinion of
Professor Hégbom in support of the competency of earth changes
to produce this depletion, and also the competency of the interior
and other sources to re-supply the impoverished atmosphere.
He, therefore, carries the suggestion of Tyndall and others a very
notable step in advance, and, what is especially important, has
given it quantitative expression on the basis of deductions from
observed data. He does not, however, postulate the conditions
which control the enrichment and depletion of the atmosphere
which has been the essential endeavor of this paper.’

But we do not meet geological demands when we simply
offer general explanations of climatic changes. Our theories
must ultimately be found to fit the precise phenomena. How
are we to explain the profound glacial oscillations? Here is
where existing hypotheses are put to the stress and our atmos-
pheric hypothesis seems at first thought even less adaptable to
the phenomena than most others. If we could deny that the
oscillations were profound, as some do, it would be convenient.
But I fear we cannot. We may appeal to variations of atmos-
pheric supply, to the precession of the equinoxes, etc., but field
experience leads me to doubt whether these will fully fit the
phenomena, though they must doubtless be reckoned as factors.
I have endeavored to follow out the doctrine of atmospheric
gain and loss on its own lines, and although the studies are
incomplete, the results are at least encouraging. I seem to find
a rhythmical action that may in part explain the glacial oscilla-
tions. To do it justice it should have elaborate and careful
statement, but I can here only suggest its nature in bald outline

*T may here remark that the main features of the ideas herein advanced were
entertained and expressed to my students some time before I saw Dr. Arrhenius’
important paper, but I fear I might not have felt justified in giving them a more pub-

lic statement but for the encouragement of his weighty opinion on the vital point of
quantitative sufficiency.

682 LCs GAN TLER ISIN,

and in terms that need qualification. The idea hinges (1) on
the action of the ocean as a reservoir of carbon dioxide and (2)
on the losses of the organic cycle under the influence of cold.
Cold water absorbs more carbon dioxide than warm water. As
the atmosphere becomes impoverished and the temperature
declines, the capacity of the ocean to take up carbon dioxide in
solution increases. Instead, therefore, of resupplying the atmos-
phere in the stress of its impoverishment, the ocean withholds its
carbon dioxide to a certain extent, and possibly even turns
robber itself by greater absorption, though the diminution of the
tension of the carbon dioxide of the atmosphere as its amount
is reduced tends to increase the discharge of carbon dioxide
from the ocean to restore the equilibrium, and, to the degree of
its efficiency which is undetermined, offsets the increased absorp-
tion of the cold water. So also, with increased cold the process
of organic decay becomes less active, a greater part of the
vegetal and animal matter remains undecomposed, and its car-
bon is thereby locked up, and hence the loss of carbon dioxide
through the organic cycle is increased. The impoverishment
of the atmosphere is thus hastened and the epoch of cold is pre-
cipitated.

With the spread of glaciation the main crystalline areas,
whose alteration is the chief source of depletion, become cov-
ered and frozen, and the abstraction of carbon dioxide by rock
alteration is checked. The supply continuing the same, by
hypothesis, reénrichment begins, and when it has sufficiently
advanced warmth returns. With returning warmth, the ocean
gives up its carbon dioxide more freely, the accumulated organic
products decay and add their contribution of carbonic acid,
and the reénrichment is accelerated and interglacial mildness
hastened.

With the reéxposure of the crystalline areas, alteration of
the rocks is renewed and depletion reéstablished and a new
cycle inaugurated. And so the process is presumed to continue
until a change in the general topographic conditions determinesa
cessation.

HYPOTHESES BEARING ON CLIMATIC CHANGES 683

The rhythmic curve which represents these oscillations
should have an increasing or declining amplitude, according to
the advance or decline of the topographic conditions which con-
trol the depletion of the atmosphere. This brief sketch needs
much elaboration and qualification, but as the studies are still in
progress, and the paper has already transgressed the limits due
the occasion, it must be deferred.

T. C. CHAMBERLIN.

AN ANALCITE-BASALT PROMPEOLONAD OF

THE discovery that analcite plays the role of an important
primary constituent of certain igneous rocks must be regarded
as one of the most interesting developments of recent petro-
graphical investigations; and I, for one, am inclined to believe
that Pirsson has not gone too far in his general conclusions, pub-
lished in this JoURNAL a year ago,’ that analcite is an essential,
primary component of many rocks now assigned to the mon-
chiquites, a rock group described some years ago by Hunter and
Rosenbusch. As each definitely proven instance of primary
analcite in igneous rocks must for some time to come be of value
in establishing its true rank as a rock constituent, the following
description is offered, although some important details of occur-
rence cannot be given. |

The rock in question was found by myself in 1893, while
engaged in the geological survey of the Pike’s Peak quadrangle.
The exact locality, which may be identified by reference to the
published map of that area,3 is in the small park called ‘‘ The
Basin,’ twelve miles nearly west of Cripple Creek. Near the
southern end of The Basin, and on its western side, at the end
of a little ridge between two branches of High Creek, there is
an outcrop of black basaltic rock directly on the line where a
great complex of andesitic and basaltic breccia and agglomerate
rests on the Dakota Cretaceous sandstone. This volcanic series
extends far to the westward, between South Park and the Arkan-
sas River, but only a few tongues and remnants now exist to
the eastward of The Basin. The outcrop mentioned was regarded

t Published with the permission of the Director of the U. S. Geological Survey.
2“ The Monchiquites or Analcite Group of Igneous Rocks,” by L. V. PIRSSON.
Jour. GEOL., Vol. 1V, 1896, pp. 679-690.
3 Geological Atlas of the United States, Pike’s Peak Folio (No. 7), Washington,
1894.
684

AN ANALCITE-BASALT FROM COLORADO 685

at the time of discovery as indicating a short dike parallel to the
ridge, but no contact was seen, owing to detritus. Although the
rock had a somewhat unusual habit, it was not supposed to be
materially different from many other basaltic dikes which had
been observed cutting the fragmental series referred to. It turns
out on examination, however, that this rock of The Basin is an
analcite-basalt, quite unlike any other rock collected in the entire
district.

The rock is dark and very fresh looking, with many small
crystals of augite and olivine, and a white mineral occurring in
roundish grains, all these averaging about 1™™ in size. A few
augite prisms are larger, and terminations exhibiting the usual
pinacoidal twinning were seen. The white mineral, by its rounded
grains and the absence of cleavage, presents the only marked
deviation from the normal habit of the neighboring plagioclase-
basalts. A black, aphanitic groundmass holds the phenocrysts.

Under the microscope augite, olivine, and magnetite possess
a development common in basalts. Augite of pale, yellowish
green color, and very faint pleochroism, occurs in phenocrysts,
which are usually almost free from inclusions, but a few aygre-
gates of similarly colored grains are full of irregular or sack-
shaped glass inclusions. There is commonly a narrow outer zone
to the purer augite, in which inclusions of glass and magnetite
are seen, and the substance of this outer rim has a faint purplish
tinge, like that of the smaller groundmass grains. An analysis
of the pure augite is given below.

Olivine appears in moderate abundance, of usual habit, and
is the only mineral showing any sign of alteration. Perhaps
half of the olivine is serpentinized with pale brown biotite leaves
inclosed in the serpentine of the most altered grains, as an
apparent secondary product. Primary dark, reddish brown bio-
tite also appears very sparingly. Magnetite and apatite have
the customary development.

A considerable part of the rock is colorless and isotropic in
polarized light; a much smaller part is colorless but doubly
refracting, and is mainly assignable to three species of feldspar.

686 WHITMAN CROSS

The isotropic constituent embraces most of what is megascop-
ically visible, and also much more, in small grains, which, with
corresponding ones of augite, magnetite, and feldspar, make up
the groundmass. There is, in fact, a regular gradation between
large and small isotropic grains. No crystal form was observed
for the isotropic substance, but neither does it appear in any way
to play the rdle of a glassy base. It seems throughout to be an
irregularly granular mineral constituent, of the isometric system.

The larger grains are almost wholly free from inclusions, and
while probably the last substance to crystallize the isotropic
mineral has in its growth pushed back the smaller grains of
augite and magnetite so that they often form a distinct zone
about it. This phenomenon seems clear evidence of a crystalliz-
ing force. Thesmaller grains mingle with augite, magnetite, and
feldspar.

While no crystal form has been observed, rings or wreaths
of small inclusions were noticed in a few grains, and these so
strongly suggested leucite that until the chemical analysis was
made I felt quite sure that the rock must bea leucite-basalt. A
smoky tinge is present in a very few grains, and in one the col-
oring matter is arranged in zones, clearly suggesting a regular
crystal form. Irregular fractures traverse the substance, and its
index of refraction is less than that of the Canada balsam, as
indicated by Becke’s method.

The feldspathic constituent appears in small, irregular, clear
particles, some of which have most characteristic microcline
structure, with an extinction of 15°; others can only be consid-
ered as sanidine, with Carlsbad twinning in some grains; and
the remainder is a plagioclase rich in soda, with very delicate
albitic twinning. Its angle of extinction is always small. There
is possibly some nepheline associated with the feldspar.

The purity, freshness and abundance of the isotropic mineral
invited the attempt to determine its composition by isolation and
analysis. This was done by Dr. W. F. Hillebrand, and the
result is given in column I of the table below. Under I|* is
given the molecular ratio deduced from the analysis. The

AN ANALCITE-BASALT FROM COLORADO 687

amount and composition of the portion of the rock soluble in
hydrochloric acid is shown in column II. The augite was, in
the main, so free from inclusions that an analysis was made by
Dr. Hillebrand for comparison with other rock augites. The
material was isolated by the Thoulet solution, and was found to
be very pure on microscopical examination. III is the analysis
of the augite.

I Ja II Ill

SHO 51.24 854 21.97 49.26
AOE 153
Al,O, 24.00 235 9.943 6.01
FeO, 1.204 Syria: SS
FeO 4223
CaO 1.62 29 1.95 21.79
SrO .06 08 06
BaO ? ?
MgO ie 8 2.87 12.40
KO gals 13 56 41
Na,O II.61 187 4.04 79
H,O .627 3.915
H,O 8.47? 470
BeOr
SOF none
Cl trace 05

100.40 49.08 99-79
WOver HsSO,. 3 Includes P,O;. 5 Assumed from rock analysis.
2 Remainder of water. 4 Total iron as Fe,O3.

The isotropic mineral could not be secured entirely free
from attached or included particles of doubly refracting sub-
stances. But these made up a small part of the material sub-
jected to analysis. After treatment with hydrochloric acid
there remained an insoluble residue, amounting to 4.22 per cent.
of the substance taken, and this was found on microscopical
examination to consist of augite and feldspar. From the molec-
ular ratio the following proportion may be derived:

SiO5 Al, On Ro Or Oh: 85 40235n-.287 2 470. oF

2:6 = vewlbeeee oT? 2
In this result CaO and MgO are united with the alkalis and iron

688 WHITMAN CROSS

is neglected. This ratio is exactly that of analcite except for
the silica. It cannot be assumed that the material isolated was
pure, and small amounts of various substances no doubt went
into solution. But we can reasonably consider it demonstrated
that the isotropic substance acting like a mineral constituent
has practically the composition of analcite. I can see no reason
for doubting this identification.

The analysis of the soluble portion of the rock leads to prac-
tically the same result as that of the isolated analcite. By
deducting olivine, apatite, and magnetite, there remains a resi-
due having about the ratio 1 : 1 for Al,O, to alkalis. Silica is
again low. If nepheline were present in the rock the low silica
of both analyses might be explained. It is possibly there in
some small amount but probably not in sufficient quantity to
entirely explain the figures of the analyses.

The augite proves to be quite high in alumina and to have
more titanic acid than would be inferred from the pale violet
tinge it exhibits. It is thoroughly normal augite.

An analysis of the rock of The Basin was also made by Dr.
Hillebrand, and it is given in column IV of the following table,
in which analyses of several allied rocks are introduced for pur-
poses of comparison. Of the other analyses, V is of a rock from
Shelburne Point, Vermont, described by J. F. Kemp and V. F.
Marsters,’ with other dikes of the Lake Champlain region, In
the original description Kemp published another analysis of this
rock, the accuracy of which he was afterward led to question,
and the analysis here quoted, made by H. T. Vulté, was published
by Pirsson, at Kemp’s request, in his cited discussion of the mon-
chiquite group. VI is of one of the original monchiquites from
Brazil, by M. Hunter. The relation between the analcite-basalt
and the other basalts of the region is illustrated by analysis VII,
by W. F. Hillebrand, of a normal plagioclase-basalt occurring in
Saddle Mountain, a few miles northwest of The Basin.

t The trap dikes of the Lake Champlain region. Bull. 107,U.S.G.5S., 1893 p. 32

2 Uber Monchiquit, ein camptonitisches Ganggestein aus der Gefolgschaft der Elz-
olithsyenite, Tschermak’s Min. und petr. Mitth. Vol. XI, 1890, p. 445.

AN ANALCITE-BASALT FROM COLORADO 689

TABLE OF ROCK ANALYSES.

TVie Vi VI. VII.
Analcite-basalt, Monchiquite, Monchiquite, Plagioclase-basalt,
The Basin, Colo. | Shelburne Point, Vt. Brazil. Saddle Mt., Colo.
W. F. Hillebrand. H. T. Vulté. M. Hunter. W. F, Hillebrand.
SiO, 45.59 45.58 46.48 48.76
TiO, T32 undet. .99 1.65
FiO) 03 76 Oh Stee none
Al,O; 2208 15.87 16.16 15.89
Fe,0, 4.97 4.65 6.17 6.04
FeO 4.70 6.37 6.09 4.56
MnO A trace meres 1
CaO II.09 9.91 Teas 8.15
SrO ae Tee: peseks .06
BaO a) Bestel SHG cil 77
MgO 8.36 8.32 4.02 5-98
K,O 1.04 1.61 3.08 2.93
Na,O 4.53 3-42 5.85 3-43
Its (O) trace eens sisters none
H,O yi ) ~ 1 ( .40
H,O 3.40 J oa S ot) / 1.48
P.O; OI rity eyes .60
Cl 05 Res cette
Cor Ser 45
99.87 98.87 100.91 100.23

Were the greater part of the water in the analcite-basalt
deducted, and the remainder recalculated to 100, the analysis
IV might stand for an ordinary nepheline-tephrite. It is lower
in alumina than many analyses of basalt, but if TiO,, P,O,,
and MgO were accurately estimated in all such rocks the alu-
mina would often fall 2 or 3 per cent. below the published figures.
The magma of this basalt was relatively quite rich in soda with
low silica and much water. The formation of analcite in the
final stages of consolidation of such a magma seems to me much
more natural than that glass should be the result, provided only
that the conditions were in general favorable to crystallization.
As the rock probably occurs in a dike and ina region where
there are many dikes of holocrystalline plagioclase-basalt, the
presumption must be that the conditions were favorable to crys-
tallization.

690 WHITMAN CROSS

The monchiquite of Shelburne Point agrees very closely in
composition with this analcite-basalt. Its high alumina would
no doubt be materially reduced if TiO, and P,O, were deducted.
Of this particular rock Kemp quotes Professor Rosenbusch, to
whom it had been shown, as saying that it is a ‘‘true monchiquite

yy

of typical habit. From a microscopical examination of a speci-
men of this rock which is in the reference collection of the
Geological Survey it is plain that there is a great difference in
the development of the two rocks. In the Shelburne Point rock
there is a cloudy gray base of indistinct radially fibrous struc-
ture and of weak double refraction. It is neither glass nor nor-
mal analcite at present, whatever it may have been originally.
It is clear from the analysis, however, that the rock of Shelburne
Point and that of The Basin resulted from magmas of almost
identical composition.

The original monchiquite (analysis VI) varies somewhat from
the others, being higher in alumina, iron and alkalis and lower
in lime and manganese. Its alumina must contain considerable
phosphoric acid. Its isotropic base, interpreted by Hunter and
Rosenbusch as glass, has been shown by Pirsson’s recalculation
of Hunter’s analysis to have practically the composition of
analcite.

The plagioclase-basalt of Saddle Mountain is so near to
the monchiquite of analysis VI in chemical composition that
if its magma had contained 2 per cent. more water it might
in all probability have yielded a monchiquite. As many normal
basaltic dikes occur near The Basin it seems reasonable to
assume that the analcite-basalt magma contained more water at
eruption than did those of the plagioclase-basalt dikes.

In the original description of monchiquite Messrs. Hunter and
Rosenbusch call attention to the association of all the rocks of
that type then known to them with eleolite-syenite, and express
the belief that magmas of this kind must have given rise to the
monchiquites together with some complementary acid rocks.
The expression of this belief in the positive form of the title to

Sell, WOv/5 Uy > (Ga Sey 19 B50

AN ANAELCITE-BASALT FROM COLORADO 6gI

their communication — ‘‘ Uber Monchiquit, ein camptonitisches
Ganggestein aus der Gefolgschaft der Elaolithsyenite”—is of
course in harmony with the well-known attempts of Professor
Rosenbusch to make geological occurrence the foundation stone
in the classification of igneous rocks. And whether one believes
or does not believe that the ‘‘dike rocks’’ of Rosenbusch have
individually or collectively that restricted geological occurrence
and that constant association indicating their origin which are
assumed in the system of that master, it is of great importance
to the development of petrography to know the facts. An asso-
ciation of rocks, the importance of which may be exaggerated
from certain standpoints, should not on that account be slighted
by those who occupy other points of view.

The analcite-basalt of The Basin occurs in a region where
there is a great series of volcanic rocks, mainly andesitic, with
basalts, trachytes, and rhyolites, all more or less prominent within
five miles of The Basin. Phonolites occur in abundance at and
near Cripple Creek, but there seems to be no reason for assum-
ing any relation whatever between the magma of this analcite-
basaltand that of the Cripple Creek center. . As has been des-
cribed' there are basic dikes at Cripple Creek, some of them
plagioclase-basalts and some containing a scanty, colorless,
residual material of indistinct character, which was interpreted
as nepheline in large part, and hence these rocks were called
nepheline-basalts. From the much decomposed condition of
these dikes I am unable to say upon reéxamination that they
may not originally have contained analcite or a glassy base, but
still believe it more probable that they were nepheline rocks.

Since it is evident that the monchiquite or analcite-basalt
magma contains nothing peculiar to itself except water, it is diffi-
cult to see why Rosenbusch should regard it as a differentiation
product of different origin from other basaltic magmas. Nor is
it plain why any significance, as to genetic relations, should be
attached to the fact that the supposed glassy base of the mon-

"Geology of the Cripple Creek District, Colorado, by WHITMAN Cross, Six-
teenth Ann. Rep. U. S. Geological Survey, 1895.

692 WHITMAN CROSS

chiquites is similar to eleolite-syenite in composition. The
residual parts of any moderately basic rock, after crystallization
of the ferro-magnesian constituents, will be identical with some
possible extremely feldspathic rock.

As for the question whether the colorless isotropic base of
the so-called monchiquites is really glass or analcite it must be
admitted that both are possible, although the former has not
been proven in any special case known to me. The point raised
by Pirsson, however, seems very important, namely, that as the
monchiquites are supposed to be rather deep-seated dike rocks,
it is much more reasonable to suppose that the residual substance
would crystallize rather than forma glass. This argument has
special weight where it can be shown that the residue has prac-
tically the composition of analcite, and where associated rocks
of the same or more silicious composition are found to be holo-
crystalline. :

The name analcite-basalt has been used for the rock here
described because it accurately expresses its relation to allied
types, because the name has priority over monchiquite through
its use by Lindgren* for the rock of the Highwood Mountains,
Montana, and further because the definition of monchiquite by
Rosenbusch implies a glassy base, which is certainly a possibility,
so that there may be rocks to which the name monchiquite
applies in the sense originally proposed. It is probable that in
many cases it cannot be demonstrated whether the colorless iso-
tropic residual matter is glass or analcite, and where decomposed
it will be clearly a matter of inference, in most instances. Criteria
will doubtless be discovered by which analcite can be more readily
determined than at present. The advisable course then seems
to be to apply the name analcite-basalt where the determination
can be rendered probable and to apply monchiquite in other
cases. The fact that an analcite-basalt would have been a mon-
chiquite if its residue had not cystallized shows the extremely
close relationship of the two rocks. But it does not follow that

*Eruptive rocks from Montana. Proc. Cal. Acad, Sci., Ser. 2, Vol. III, 1890, pp.
39-57 (reference).

AN ANALCITE-BASALT FROM COLORADO 693

all monchiquites would have yielded analcite-basalt on crystalliza-
tion, for the ratio of SiO, : Al,O, : R,O0 : H,O must probably
be vety neatly/4.; 131: 21\in order that this unusual rock con-
stituent may form. With lower silica, nepheline and analcite,

or glass, would presumably result.
WHITMAN Cross.

SIUIDIOSS OW Wells; SO2CAEILIEID WOMEN GINIEISS
OF NEW HAMPSHIRE.

CONTENTS.

Introduction.
Historical summary of opinion on the “ porphyritic gneiss.”’.
Geographical distribution of the formation.
Brief description of the rock-nomenclature.
Field relations.

The Winnipiseogee area.

The Ashuelot area.

The Main area.
Contact Metamorphism.
The origin of the foliation. Criteria of flow structure.
Significance of the uniformity of the porphyritic granite.
Pegmatite veins cutting the porphyritic granite.
The age of the intrusions.
Summary.

Introduction.—The following paper embodies the results of
some weeks of field work on the New Hampshire terrane,
heretofore considered by some writers to be a metamorphosed
Archean sediment, but suspected by others to be eruptive. The
conclusions of the author corroborate this suspicion and he has
attempted to express them here with the special point in mind.
The author desires to express his best thanks to Professor J. E.
Wolff, of Harvard University, for valued suggestions and very
material aid during the progress of the work.

fiistorical summary of opinion on the ‘‘porphyritic gneiss.’’—From
the conspicuous nature of its outcrops the ‘‘ porphyritic gneiss” of
New Hampshire early attracted the attention of geologists. In
the first annual report of the Jackson survey, in 1841, Whitney
and Williams, in describing its occurrence remark that “large
bowlders of porphyritic granite are very numerous over the sur-

694

SO-CALLED PORPHYRITIC GNEISS OF NEW HAMPSHIRE 695

face, from the west parish of Concord to the center of Warner,
where we find the rock itself in place. It is a peculiar rock,
having large crystals of feldspar uniformly distributed through its
mass ; they are often glassy, so as to furnish beautiful and striking
specimens. This bed of granite extends across the state in a gen-
eral northeast and southwest direction. It is from eight to ten
miles in width, though often interrupted with veins of granite of
various texture.”? With the physical difficulties of a rugged, for-
est-clad country, it was not to be expected that accurate determina-
tions of boundaries could be made by these geological pioneers.
To this fact is due the confusion of the ‘‘porphyritic gneiss” and
associated schists in the published Portsmouth-Claremont sec-
tion of the Final Report.

In their section, ‘“‘from Haverhill to the White Mountains,”
Whitney and Williams again refer to the formation thus:
“From Meredith to Centre Harbor the rock in place is por-
phyritic granite, often traversed by beds and veins of fine
grained, dark colored granite and trap. Some specimens of the
porphyritic granite, in which the crystals of feldspar are flesh
colored, are wweny beamtituls o>)... ‘‘From Centre Harbor to
Plymouth the rock in place is porphyritic granite, traversed by
occasional beds of mica slate.’’?

The first distinct mention of the ‘‘porphyritic gneiss” in the
second (and last) survey of the state, that under the control of
‘Professor C. H. Hitchcock, occurs in the second annual report,
1870. The preliminary map issued with that report roughly
outlines the formation which he calls porphyritic granite. He
describes it as ‘‘common granite full of large crystals of
feldspar, generally from one-half of one to two inches long,
which gives a checked appearance to the ledges. Some portions
of it have evidently been injected, while the arrangement of the
feldspathic crystals in parallel lines leads to the suspicion of
stratification in other cases. When accurately mapped the area
will resemble the trunk and branches of a decayed tree, the

‘Final Report on the Geol. of N. H., C. T. JACKSON, 1844, p. 51.

2Op. cit. pp. 73 and 137.

696 NSH CSONEULIO! AIO VM OVR AIS. JOVAIL NZ

branches corresponding to the veins which have been injected
from the original mass."

In the yreporte fornvthe mext year) kirofessonmaitehcoes
adopted the view which was held throughout the later publica-
tions of the survey. On the map, of a scale of five miles to one
inch, he differentiates the Lake Winnipiseogee and White Moun-
tain areas, and gives a brief description of the rock, to which
INS VENIDXES WS MENS “lxorplyiatine emesis, Isle Sayse Wins
is an ordinary gneiss, carrying numerous crystals of orthoclase
or potash-feldspar, from a quarter of one to two inches long.
The longer axes may be parallel to the strike or arranged
helter-skelter. It passes into granite with the same porphyritic
peculiarity of structure. . . . . We suppose this to be the oldest
formation among the mountains. Geologists speak of a rock of
this character as common in the Laurentian in various parts of
North America and Europe.’’?

At the twenty-first meeting of the American Association for
the Advancement of Science, held in 1872, Professor Hitchcock
expressly referred the ‘“‘prophyritic gneiss” to the Laurentian$
and noted the common parallel structure of the rock which he
concluded to be the trace of an almost obliterated stratifi-
cation.

An indication of doubt as to an exact correlation appears in
Professor Hitchcock’s ‘Classification of the Rocks of New
Hampshire,” published in 1873.5 He divides the various forma-

Second Ann. Rep. upon the Geol. and Mineralogy of N. H., 1870, p. 33.

2 Geology of New Hampshire, 1874, Vol. I, p. 33.

3Explanation of a New Geological Map of New Hampshire. Proc. A. A. A.S.,
1872, p. 134.

4Recent Geological Discoveries among the White Mountains, N. H. Proc. A.
A. A.S., 1872, p. 135. In this paper the author states his grounds for the correla-
tion, viz., that of lithological similarity between the porphyritic gneiss and the Lau-
rentian of Canada and Europe. At each of the next two meetings of the Association,
he reaffirmed his position that there is nothing older in the state than the porphyritic
gneiss which was held to be Archean in age. See Geological History of Lake Winni-
piseogee. Proc. A. A. A. S., 1873, B. p. 122, and the Physical History of New
Hampshire, zézd., 1874, B. p. 76.

5 Proc. Bos. Soc. Nat. Hist., Vol. XV., p. 304.

ad

SO-CALLED PORPHVRITIC GNEISS OF NEW HAMPSHIRE 697

tions of the lower series into two groups—the Laurentian, which
he qualifies by an interrogation point, and the Labradorian. The
former included the ‘‘porphyritic gneiss,’ Bethlehem gneiss,
White Mountain, or andalusite-gneiss, and the breccia of Fran-
conia, in the order of decreasing age. The eight members of
the Labradorian ‘“ constitute one horizontal series of formations,
the lowest resting upon the upturned edges of all the parts of
group I.” The greater antiquity of the “porphyritic gneiss”
than thaworm une souner series “is inferred from the occurrence
of several bands of andalusite and granitic gneisses upon both
flanks.”” Itis interesting to note that in discussion on this paper
Dr. C. T. Jackson declared his belief that ‘‘the classification pro-
posed was hypothetical to a great extent, and that sufficient
reason for the adoption of the New York nomenclature was not
shown.”

The first volume of the Final Report of the Hitchcock Sur-
vey was issued in 1874. The ‘ porphyritic gneiss’’ was there
explained as the product of altered sediment, the primitive
stratified rocks having been metamorphosed in Archean, or, as
then expressed, Eozoic time.t The second volume, published
three years later, reiterated this opinion, making the terrane the
representative of the ‘first territory in the state that was
redeemed from the primeval ocean.’

‘“A porphyritic, or augen-gneiss, is eminently characteristic
of the fundamental rocks in every part of the world, and hence
ours may readily be called Laurentian.’’3 A still closer correla-
tion was suggested whereby the “ porphyritic gneiss” of the
White Mountain district, and inferentially that of the whole state,
was put in the ‘‘upper division of the Laurentian system, as it is
developed in Canada and New York.’* In the general résumé
of the stratigraphical relations, a thickness of five thousand feet
was estimated for the formation. With it was included the
‘younger Bethlehem and Lake Winnipiseogee gneisses to form
the whole Laurentian, aggregating 34,900 feet in thickness.

=(Caolk OF INic ley WOlls Ie, me joe Ie 3 [oid., p. 668. 5 [bid., p. 668.

(Ell OF ING Isl, Wola Wh USF jos Huo) 4 Tbtd., p. 252.

698 REGINALD ALDWORTH DALY

From this brief review it is seen that the placing of the
‘“porphyritic gneiss’ so low in the geological scale was largely
due to the prevalence of two pernicious doctrines then held in
the study of crystalline schists. The application of the ‘‘litho-
logical canon”’ was a constant feature in the efforts of the sec
ond survey to work out their difficult field. The coarse granitic
eneisses, the augen-gneiss, and the andalusite-gneiss were each
supposed to be represented in the typical Laurentian of the
better known regions, thereby establishing synchrony. Again
the distinct foliation in many parts of the ‘‘ porphyritic gneiss ”’
led to the other serious error of considering the rock as a meta-
morphosed sediment, which still preserved traces of its original
planes of stratification.* This position being taken, it was but
natural to look for structural relations with the surrounding for-
mations, and at many contacts, the greater antiquity of the por-
phyritic rock would often appear evident. Needless to say, how-
ever, in the light of present knowledge, that all such reasoning
is without foundation so far as it refers to large isolated areas of
thoroughly crystalline schists. Thus the character of the
terrane had to be determined by other methods. The latter were
very sparingly used by the survey, and consequently its final con-
clusions assigned to the ‘‘porphyritic gneiss” the very important
position of a foundation member in the entire geological series.

The interpretation of other terranes was, of course, greatly influ-
enced by this fundamental idea. The survey fixed the geologi-
cal position of the Bethlehem gneiss,? and of the Montalban
group and the Lake Winnipiseogee gneiss 3 directly by reference
to the ‘‘porphyritic gneiss,” and the later succession was corre-
spondingly affected. In fact, Professor T. Sterry Hunt’s con-
ception of and nomenclature of the Montalban group was
founded on the conclusion that there is this demonstrable Lau-

rentian in New Hampshire.

' Geol. of N. H., Vol. II, p. 99.

Zitis\7ily sae Ceol, Ot ING Jala Wolk Il, jos B43 Wolk Wh joy AS.
3 [bid., Vol. II, pp. 564,662.

4 Geol. Mag., 1887, p. 1499; Nature, Sept., 1888, p. 52.

SO-CALLED PORPHYRITIC GNEISS OF NEW HAMPSHIRE 699

We have already referred to some hints of an igneous,
intrusive origin for the ‘‘ porphyritic gneiss,” that were given by
the survey officers. Similar suggestions appear in many parts of
the different reports.t The facts described in these passages
were supposed to be explained on the metamorphic theory as
being characteristic of only those parts of the ancient stratified
rocks which had been altered to the extent of complete fusion.

In his address as vice president of section & of the Ameti-
can Association in 1883, Professor Hitchcock expressed some
modification of his earlier opinions on the origin of the por-
phyritic gneiss. Hesaid: ‘A careful study of the crystalline
rocks of the Atlantic slope indicates the presence of scattered,
ovoidal areas of Laurentian gneisses. Those best known have been
described in the geology of New Hampshire. Instead of a few
synclinal troughs filled to great depths with sediments, the oldest
group is disposed in no less than twenty-two areas of small size,
scattered like the islands in an archipelago. There are no
minerals in these Laurentian islands that do not occur in eruptive
granite ; and the schistose structure is often so faint that the
field geologist need not be blamed if he acknowledges his inability
to detect it. Likewise we discover the same fluidal inclusions
and the vacuoies that pertain to granite.’3 Comparing these
islands to volcanic oceanic islands of the present day, he suggests
that the foliation of the porphyritic gneiss may be the result
of the superposition in quaquaversal sheets of lava about each vol-
canic cone, aided by flows of mud and wear by water between
igneous flows. In this way we might have a ‘“ concentric stati-
form arrangement in the whole mass.’’ Subsequent metamor-
phism by heat and pressure would lead to the development of
new minerals in foliated beds.

The next important notice of this formation appears in Whit-
ney and Wadsworth’s ‘‘ Azoic system.’’* They instituted a close

“isis Ceol, GEING Isl, Il Dh B75 BSB IWS eh Ow, aya, Gack

2RLOC WAAL EAG SEL OOR WE DaloO.

S1Op cite, Palo.

4 Bull Mus. Comp. Zool., Harvard College, Vol. VII, 1884, p. 383 ff.

700 REGINALD ALDWORTH DALY

criticism of the general methods of the New Hampshire survey,
and looked with especial disfavor upon the liberal use of the
as accepted by the members of that survey.

”

“lithological canon,
A convenient résumé of the various classifications proposed for
New Hampshire rocks is given in tabular form at page 396 of
the memoir. The possibility of an eruptive origin for the
‘“‘porphyritic gneiss ’’’ was remarked by the authors.

In 1884 Professor Hitchcock stated that ‘all thoroughly
crystalline series of the Atlantic region are of Eozoic age.’’*
Two years later he edited the ‘‘ Geological Map of the United
States,” in which the “‘porphyritic gneiss” is colored as Lauren-
tian.2 A somewhat full account of his opinions on the forma-
tion was given ina paper on the “ Significance of Oval Gran-
itoid Areas in the Lower Laurentian,’3 from which it is evident
that in 1890 Professor Hitchcock held practically the same views
on the present subject as those which he published in 1883.

While the present paper was in process of preparation the
last word on the formation was given by Professor Hitchcock in
this JourNnaL. After tracing in a general way the history of
geological surveying in New Hampshire, he makes the following
significant statement of a changed point of view: ‘“‘The question
now arises, how can our early classification [ of the rock series |
be improved? It is eighteen years since the New Hampshire
report was published, and there are many new workers in the
field, all placing great reliance upon petrographical principles,
such as were inaugurated in Dr. Hawes’ report. Some are
advocates of extreme metamorphism, and hence the conclusions
are not harmonious. It seems to us that our early views may
be modified by the following principles: (1) The mineral
characters of crystalline rocks are not a sure guide to geological
age. (2) Protogenes, diabases, and diorites, more or less inter-
stratified with hydro-micas, are of true igneous origin. (3) The

*Trans. Am. Inst. Min. Eng. XII, 1884, p. 68. Cf. a paper in Proc. A. A.A.S. of
the same year (p. 396) where he again holds the porphyritic gneiss to be Laurentian.

? Trans. Am. Inst. Min. Eng., Vol. XV, 1886, p. 465.
3 Bull. Geol. Soc. Am., I, 1890, p. 557.

SO-CALLED PORPHYRITIC GNEISS OF NEW HAMPSHIRE 70!

Archean gneisses and protogenes may also be of igneous origin,
and their apparent stratification has no connection with sedi-
mentary or chemical deposition, etc. .... Applying such prin-
ciples to the classification of the rocks of northern New England,
we may improve on the report in several particulars. (1) Arch-
gan rocks are not eliminated from our list. They exist as oval
areas, such as have been indicated in the Stamford gneiss, and
south of Mount Killington, Vt., in the Hinsdale, Mass., area, the
Hoosac Mountain, and elsewhere. I recognize the porphyritic
gneiss in the Stamford rock, and in the Hoosac tunnel as Arch-
ean. (2) Our hesitancy about the place of the Bethlehem
gneiss is met by recent observations. They are batholites, con-
taining inclusions of the adjacent mica-schists. It does not
follow that all these protogene areas are of the same character ;
each one must be studied by itself.’’*

However satisfactory such conclusions may be in their appli
cation to most of the formations in the state, a clear statement
of the true relations of the porphyritic gneiss has not yet been
made. The author’s recognition of the correct methods which
must be used in interpreting crystalline schists has as yet not
been supplemented very largely by their positive exercise in the
field, and the implication in the foregoing extract that the

”)

Archean appears in the state in ‘“‘oval areas,” either igneous or
non-igneous, is still without demonstration.

We shall hereafter adhere to the name porphyritic granite,
for the rock under discussion instead of porphyritic gneiss
‘which has been so far used. As will appear later, the former
name, while not embodying all the generalized features of the
rock, is preferable to the official one of the second geological
survey.

Geographical distribution—The porphyritic granite, as shown
on the survey maps, occupies four large areas with several
smaller ones. Of these the largest one extends from Mount
Monadnock, N. 5° E. to the northern flank of Cardigan Moun-
tain, a distance of sixty miles; while it varies from three to

*The Geology of New Hampshire. Jour. GEOL., Chicago, Vol. IV, 1896, p. 57.

702 REGINALD ALDWORTH DALY

twelve miles in width. Since this occurrence covers more than
four times as many square miles as any other, it may well be
called the ‘‘ Main area.’’ Associated with it in Sullivan, Merri-
mack, and Hillsboro counties, are some half dozen much smaller
outcrops of the same rock which are surrounded by schists, and
are thus outliers from the larger mass. Twelve miles west by
south of Mount Monadnock, a second important mass of regular
elliptical or oval-shape cuts cross the Ashuelot division of the Bos-
ton and Maine railroad. The longer axis runs north and south,

and is about ten miles long, while the shorter, transverse to the

g,
former, is six miles long. From the village of Ashuelot, situated
on porphyritic granite, we shall derive a distinctive name, and
call this the ‘‘ Ashuelot area.” The survey has mapped a large
‘White Mountain area,

ted form at the north of the Main area from Mount Stinson to

”)

which ts distributed in irregular elonga-

Mount Lafayette. Some twenty miles long, it also varies con-
siderably in width, being only a mile wide near the Profile
House, but broadening out to six miles at the Kinsman Notch.
From there a long tongue of the rock runs southerly down the
valley of the Pemigewasset River. The strike of this area is
like that of the Main area, a few degrees east of north. Follow-
ing the common axis of both areas northward from the Profile
House, a small but important ‘‘Littleton area” of some eight
or ten square miles in extent, appears near the town of Littleton.
The fourth widespread occurrence of the porphyritic granite is
found in another irregular mass thirty miles long, and from one
to eight broad, running parallel to the Main area from Laconia
to Waterville. This may be referred to as the ‘‘ Winnipiseogee
area,’ from its proximity to the beautiful lake of that name.
The very local outcroppings of this rock in other parts of the
state are in point of size insignificant, but they are of value in
helping to determine the relations of the whole formation. Nota-
ble among these are the small patch on the top of Mount Prospect
west of Squam Lake and the long dikelike mass north of New
Boston in Hillsboro county. The grounds for coloring in the
mass of porphyritic granite at the southeast base of Mount

SO-CALLED PORPHYRITIC GNEISS OF NEW’ HAMPSHIRE 703

Monadnock did not appear to be corroborated by the present
writer in a somewhat careful study of that region. The mantle
of glacial drift is there very heavy, but the few outcrops which
were discovered seemed to prove the bedrock to be of the same
nature as the schists round about. Again, a visit to Mount
Osceola showed that the area of porphyritic granite plotted on
the survey map as occurring on its southern side is really
occupied by the same coarse-grained hornblende-granite which
occurs in the bed of Mad River, the ‘‘Conway Granite”’ of the
survey. ,

So great being the extent of the formation, it was impossible
in the time at the disposal of the writer to make a close exam-
ination of all parts of the porphyritic granite. Accordingly,
most of the observations in the following pages refer to three
areas, the study of which promised to be most fruitful in the
problem before us. Those selected were the Winnipiseogee
area, the Ashuelot area, and the contact of the Main area
from the town of Jaffrey to Henniker on the Peterboro and
Hillsboro branch of the Boston and Maine Railroad. We shall
consider these areas separately, treating of the geological results
obtained in each along with certain other facts whose arrange-
ment would be difficult by any other method of discussion.

Brief description of the porphyritic granite— General macro-
scopical descriptions of the granite are given in several parts of
the ‘Geology of New Hampshire.” The rock is remarkably
simple in its phasal differentiation; so far as a considerable
collection shows, there are only two important variations in
it throughout its whole extent. It may be either a porphy-
ritic granitite or a porphyritic granite proper, and either of
them may have the foliated structure. They pass into each
other by insensible gradation in all the areas and it seems to be
impossible to map them separately. With the exception of this
and a few other variable features noticed in the sequel, the por-
phyritic granite is essentially uniform; it is thus possible to dis-
miss its characterization in a comparatively summary manner.
In a future paper, the author hopes to give an account of certain

704 REGINALD ALDWORTH DALY

petrographical features whose description here is not rendered
either advisable or necessary for our present purpose.

The name “‘porphyritic granite” for this rock is regarded as
the best available one both on the ground of inherent meaning

f

Fic. 1.— Photograph of a specimen of the porphyritic granite—obtained near
New Hampton Centre — illustrating general habit of granitic phase, twinned pheno-
crysts, etc.— about natural size.

and of precedent. The composition and order of crystallization
make it a true granite rather than a gneiss although the pseudo-
schistose structure is so generally present. For very similar
ae BB ean s seas DD (56 Taq] 1 2)
rocks, the names “ granite-porphyry,” ‘‘gneissic granite,” etc.,

SO-CALLED PORPAVAITIC GNEISS OF NEW HAMPSHIRE 795

have been employed. It seems best to use the original name at
first used by each of the New Hampshire surveys and in this we
follow the nomenclature of Lehmann, Sederholm, Giimbel and
others who have dealt with very similar rocks.

Fic. 2.— Photograph of a specimen of the porphyritic granite, showing a foliated
phase near Hancock Station. The lowest phenocryst displays two prismatic partings
besides the normal cleavages, parallel to Pand JZ. The base is nearly in the plane
of the paper. About one-half natural size.

The granite is always striking and handsome in appearance
The groundmass is a coarse-grained, light to dark gray, granular
aggregate of quartzand feldspar interspersed with flecks, blotches
and lines of greenish muscovite and brilliant brown biotite.

706 REGINALD ALDWORTH DALY

Within are embedded the lustrous phenocrysts which generally,
though not always, lie in the foliation plane when the rock has
the plane-parallel structure.

The phenocrysts are glassy to opaque white and seem to be
in every case either orthoclase or microcline, which may be inter-
grown with another (triclinic) feldspar in the usual microper-
thitic fashion. The largest ones are as much as twelve centi-
meters long. The usual habit is that of simple Carlsbad twins.
They present straight edges to the surrounding matrix, giving the
planes (001) (O10) (110) and (101). This idiomorphic appear-
ance is often lost in the slide through the great amount of resorp-
tion and marginal corrosion. Occasionally small shreds of biotite,
a minute individual of apatite, or a few grains of quartz may
appear in the core of the feldspar, but as a rule it is notably free
from primary inclusions. The results of decomposition are nor-
mal. The changing to a reddish hue is common in some weath-
ered phases.

The matrix of the rock is simply a typical coarse granitite
on the one hand or a granite proper (in the classification of
Rosenbusch) on the other, in either case with or without the
foliated structure. The feldspars have the same general charac-
ters as those of the earlier generation except that a triclinic
feldspar, probably andesine, now appears as an independent con-
stituent. Quartz, biotite and muscovite constitute the other
essentials. Large but relatively few individuals of magnetite,
titanite, apatite and zircon are accessory. The quartz and feld-
spars are roughly equidimensional with diameters becoming as
much as a centimeter in length; in fact the feldspars are often
transitional into the phenocrysts. Quartz very often crystallized
simultaneously with the feldspars resulting in the formation of
a true micropegmatite which is extremely common in slides of
the granite from all the areas. It is best shown in specimens
collected along the railroad from Hinsdale to Ashuelot. There
can be little doubt that the structure is primary in the formation
as a whole. It is possible, however, that in zones of stress
the development of the structure has been aided by the meta-

SO-CALLED PORPHVRITIC GNEISS OF NEW HAMPSHIRE 707

morphic cause of crushing, as described by Howitt, Hobbs and
other writers.

The proportions of phenocrysts to matrix and of acid to basic
constituents are quite constant in the porphyritic granite. The
latter relation is that usually found in most highly acid granites.
Now and then, a well-foliated segregational mass of biotite,
quartz, much titanite and apatite, wrapping about phenocrystic
cores of feldspar, may be encountered. Again, a phase of the
rock nearly devoid of phenocrysts is not rare, although quanti-
tatively it is insignificant as compared with the porphyritic
phase. Both of these variations from the type will be discussed
in what follows.

Field relations: The Winnipiseogee area —The general dis-
tribution of the porphyritic granite in the Winnipiseogee area is
described at length in ‘“‘The Geology of New Hampshire.”’*

The topography of the area is, on the whole, not of a very
definite nature. The greater reliefs, which vary from 800 to
1500 feet above sea level, are without distinct trends, and are
the forms which might be expected as the result of eroding a
massive rock of pronounced homogeneity. Upon this rolling
ground the glacial drift has been deposited in unusual thick-
ness, especially in the southern half of the area, where the hills
are commonly composed of washed drift and till. Correlative
with glacial reliefs are the glacial depressions seen in the
numerous lakes and ponds which make such picturesque variety
in the landscape of Carroll county. These modern deposits
make it difficult to work out the relations of the bed-rocks.
The variety of outcrops in many parts renders the determination
of contact lines almost impossible, and it is largely to this cause
that the suppositional nature of some of them is due.

The geological relations of the Winnipiseogee area.—TVhe sur-
vey map places the porphyritic granite of this area in contact
with the Lake Winnipiseogee gneiss, the Montalban group of
schists, the Rockingham mica-schist, and the vartous eruptive
masses of Waterville. For convenience we shall briefly indicate

Viol sip 5O2.

708 REGINALD ALDWORTH DALY

the facts of field observation which have been adduced in con-
nection with each of these formations.

The porphyritic granite in contact with the Lake Winnipiseogee
gneiss.—Close by Gilford Station, on Smith’s Neck, the bound-
ary line of the porphyritic granite and the Winnipiseogee gneiss
appears, and, so far as known, this is its most southerly exten-
sion in this district. It is a typical acid biotite-gneiss at this

place, elsewhere muscovite may be found. A few of the out-_

crops are significant. Here and there in the porphyritic granite
masses of rock very similar to the main body of the schist occur
in a horselike relation, although nowhere could the actual contact
be found, and thus render possible a proof of that derivation of
the masses. On Governor’s Island, two miles to the westward,
a large outcropping of a coarse muscovite-biotite-gneiss occurs.
This is a typical representative of the Lake Winnipiseogee gneiss,
and this mass is completely surrounded by porphyritic granite
for a distance of at least a quarter of a mile in all directions.
About that distance from this outcrop of schist, the real contact
of the porphyritic granite and Lake Winnipiseogee gneiss was
found, and it became evident that in the first occurrence we had
to deal with an outlier removed by some means from the parent
schist terrane. This relation could hardly be explained except
on a hypothesis of the igneous intrusion of the coarser rock in
which the schist was enclosed as a great horse. The truth of
this supposition was strengthened by the discovery of two marked
apophyses of the porphyritic granite running into the inclusion.
Returning to the molar contact, a corroboration of our conclusion
from a study of the outlier appears in a clearly defined tongue
of the porphyritic granite which can be traced for some dis-
tance into the schist. Whereas on Smith’s Neck the porphyritic
granite was largely granitic, here a well-defined foliation char-
acterizes the rock. The strike of the foliation planes is N. 3° E.,
and the dip is 82° to the east. It is noteworthy that the strike
and dip of the schistosity in the adjacent schist is the same. In
other words, there is an apparent conformity between them. At
several places among the numerous outcrops of porphyritic gran-

— 7

SO-CALLED PORPHVRITIC GNEISS OF NEW HAMPSHIRE 709

ite on the island, very coarse pegmatitic dikes appear which are
similar to the granite, and do not appear to belong to the class
of pegmatite veins of segregational origin so common in the
crystalline area of the state.

About a mile and three-quarters from Weirs there is a small
inlet, on the south side of which the porphyritic granite is in
contact with a dark coarse-grained gneiss. This seems to be
equivalent to the Lake Winnipiseogee gneiss. It is cut by an
apophysis of the porphyritic granite, and a horse of the schist
can be seen on the bare ledges enclosed within the other rock.
Again, as on Governor’s Island, there is an apparent conformity
of position.

Just across Meredith Bay, on Spindle point, an interesting
contact occurs. The porphyritic granite outcrops occasionally
on and about the road from Meredith with pretty definite folia-
tien, the strike varying from N. 20° Eto N..4o° E., the dip
high, but changing from easterly to westerly in an irregular
fashion. On the top of the hill at which the road ends, an
solated mass of another rock is conspicuously displayed in the
well-smoothed ledges. It is dikelike in its form, being fully
four hundred yards long and from ten to twenty wide. There
is a distinct schistosity with its planes parallel to the longer
axis of the mass which strikes S. 4o° W. The dip is high
at about 75° to the southeast, making an apparent conformity
with the enclosing porphyritic granite, which is here well foli-
ated. Within a distance of 300 yards south of this long band,
and oriented with the longer axis parallel to it, smaller bodies
of the same rock occur, again completely enclosed by porphy-
ritic granite. They have the same pronounced structure-planes
with a similar relation to the foliation of the country rock.
From the hill top the largest of all these parallel bodies strikes
toward a larger body of the same rock. Like the other, this
mass is characterized by a strong gneissic structure. It also pos-
sesses an elongated form. We have here to deal with a number
of horses immersed in a once molten magma which chrystallized
out as porphyritic granite. The patent differences of grain and

FLO KS GTN ATED VALED VORA DATA

structure, the sharp boundary between the two rocks, the irreg-
ular thinning and thickening along the length of the inclusions,
all point to this belief. Here and there, within their boundaries,
obscure apophysal extensions of the coarser rock may be
observed. But this conclusion reaches practical certainty when
the molar contact of the porphyritic granite and the ‘“ Lake
Winnipiseogee gneiss”’ is studied. The latter is seen to be pre-
cisely the same coarse-grained biotite-gneiss as that in the
inclusions, except for certain differences which can be explained
as due to exomorphic change wrought by the porphyritic
granite. Apophyses of the latter may be seen at the neck or
isthmus of the peninsula cutting the gneiss. An important rela-
tion subsists between this line and the arrangement of horses on
the hill. Not only are they parallel to one another, but they lie
parallel to the line of molar contact.

Transition zone at Centre Harbor.—At Centre Harbor the
gneiss lies on the east side of the boundary and at some dis-
tance from it is the usual coarse-grained muscovite-biotite
rock of the Lake Winnipiseogee gneiss terrane. Its foliation
planes strike N. 15° W., and the dip is about 60° easterly. As
one approaches undoubted porphyritic granite through a dis-
tance of fifteen feet from the contact, one notes the large ortho-
clase and microcline feldspars two inches long, which normally
are confined to the porphyritic granite, now scattered through
the finer-grained rock with their longer axis parallel to its
schistosity. They grow more numerous as the porphyritic
granite is neared, until finally some four or five yards from their
first appearance, the outcropping rock is typical porphyritic
granite. It possesses the same strike and dip as the gneiss,
being well foliated. There is thus a complete and slow gradua-
tion of the one terrane into the other, making it impossible to
draw any line between them.

Transition zone near New Hampton Station—A similar zone
of transition between these two terranes occurs a mile and a
quarter from New Hampton Station on the road running south-
east from the station. The zone of passage is here much wider

SO-CALLED PORPAYVRITIC GNEISS OF NEW HAMPSHIRE 711

than at Centre Harbor, but the properties of its magmalike
gneiss with the sprinkling of large porphyritic crystals of feld-
spar are identical with those of the other locality. Asa rule,
there is a sharp contact between the porphyritic granite and the
invaded rocks, like that which in general characterizes plutonic
bodies. These belts of transition have at first sight a puzzling
appearance. That they are, in reality, eruptive contacts seems,
however, to be unquestionable. Durocher long ago noted such
an intimate union along the boundary of gneiss cut by stock-
granite. He considered the temperature of the igneous rock in
such instances sufficiently high to produce a melting up of the

bf

gneiss the “ particules”’ of which ‘‘ont dtii posséder une assez
grande mobilité, et cristalliser a peu pres dans les mémes condi-
tions que les molécules du magma granitiques.* In his ‘‘ Geog.
Beschreibung Bayerns,’’* Gumbel speaks of there being numer-

d

ous transitions from ‘‘bunter gneiss’ to ‘“‘ bunter granit ’’ which
cuts the former. Michel-Lévy has very clearly discussed the
plucnomenon im general Ee says:3-> ““C’est ici le cas de
remarquer que lorsque deux grandes masses de roches acides se
touchent, le plus souvent elles se trouvent réunies par une zone
de passage plus ou moins puissante, dans laquelle les caractéres
pétrographiques des deux roches sont, pour ainsi dire, confondus
et mélangés.t In the same paper from which this quotation has

been taken, the author cites many examples of such transition,
among which that from granite to gneiss’ and that from
granite to ‘‘micro-granulite”’ may be especially mentioned. He
explains them as due to an impregnation of the older rock by
‘‘les éléments fluides en voie de dégagement ”’ from the igneous
rock. When the temperature and pressure are suitable, a part

*Mém, de la Soc. Géol. de France, 2¢ sér. t. VI, p. 47.

? Abtheil. II, p. 272.

3 Bull. de la Soc. Géol. de France, 3° sér., t. VII, 1878-9, p. 852.
4Cf. Ch. Vélain, Conférences de Petrographie. Paris, 1889, p. 6.

5 Cf. LEHMANN, Untersuch. iiber die Ent. der alt. kryst. Schiefergesteine, p. 76.
GREGORY, Q. J. Geol. Soc., 1894, p. 260 ff. BARROW has noted a complete amalga-
mation at the contact of granitite and diorite, of which the former is the intrusive
member, Q. J. Geol. Soc., 1892, p. 121.

Ie REGINALD ALDWORTH DALY

of the constituents of the older rock will become mobile and
will tend to assume the same structure as those of the second
period of consolidation in the younger rock.

McMahon pointed out how difficult it was to explain the pres-
ence of zones of transition about the Dalhousie granite of the
Himalayas in some places and their absence in others on the
old metamorphic theory of the central gneiss. He favored
the opinion that, whether a zone of passage characterizes the
contact or not, depends on the closeness of mineralogical sim1-
larity between the Dalhousie granite and the invaded strata.
Only in places where the latter had been regionally metamor-
phosed did he find the appearance of gradual change from the
granite into the country rock. The transition zone described
by Lawson between the Laurentian gneiss and hornblende-schist
in Rainy Lake region is so similar to the zones of the porphyritic
granite that it will be well to read his own words on the subject:
“Within the hornblende-schist, distinctly recognizable as such,
there may occasionally be detected large crystals of red feldspar,
which is quite foreign to these rocks, as if the feldspathic magmas
had penetrated within the schist and crystallized there in the
same large crystals in which they are wont to appear in the
coarse gneiss.”

These authentic determinations of transgressive junctions
between plainly eruptive rocks and their respective country
rocks, coupled with the expectation that they should appear in
contacts of that nature, lead us to follow Gregory ? in concluding
that they may form a useful criterion for a decision on an
eruptive origin for massive rocks. So far as this principle is
concerned then, the porphyritic granite can be eruptive.

The foregoing description of contact phenomena seems to
us to indicate that the porphyritic granite has been intruded into
the schistose rocks which have been grouped together in the
terrane of the Lake Winnipiseogee gneiss by the survey. This
conclusion is forced upon one as well in the study of the northern

tAnn. Rep. Ceol. Surv. Canada, 1887-8, Part. F. p. 33.

JOM Geos SocamSo4nps2o2%

SO-CALLED PORPHYRITIC GNEISS OF NEW HAMPSHIRE 713

extension of the “fishhook” as in the southern part to which
attention has been so far called.

The porphyritic granite in contact with the Montalban group of
schists—We shall not consider in this place the grounds on
which the survey has separated the Lake Winnipiseogee gneiss
from the Montalban group. Our field observations have shown
us pretty clearly that, although the lithological characters of
the two terranes may be on the whole different, any distinc-
tion between them from a supposed difference of age is as yet
without demonstration. Be this as it may, the problem before
us can be solved without either proof or disproof of such a
contention. At many points along the contact, the schists of
the Montalban group are intersected by apophyses from the
porphyritic granite, and appear as inclusions in the latter rock.
The evidences of an intrusive origin for the porphyritic granite
are of the same nature as in the case of the Lake Winnipise-
ogee gneiss, and are just as conclusive.

The Montalban group and porphyritic granite come in con-
tact along the line running from Long Bay to Great Bay, and
about one half mile east of Great Bay. Here a number of
well-marked horses of the neighboring Montalban gneisses
occur in the porphyritic granite. They possess a thoroughly
gneissic structure, being as well foliated as their parent mass less
than a hundred yards away. In this case the horses are not
elongated and do not show any definite relation of position,
either to one another or to the main contact line. Apophyses
of porphyritic granite were also discovered along this part of the
boundary.

An interesting occurrence of the gneiss appears in the road
on the north side of Shaw’s hill. It is isolated and completely
surrounded by porphyritic granite whose nearest molar contact
is nearly a mile away. This great horse is highly schistose, and
several tongues of the granite here and there cut across the
structure planes. The development of garnets in the horse may
hint at some degree of contact metamorphism.

A second large horse which is some distance from its parent

714 REGINALD ALDWORTH DALY

terrane outcrops one mile anda half north of Holderness on the
upper road. Here a gigantic slice of the country rock, about
sixty feet wide and three hundred feet long, has been floated
off and rests with its longer axis north and south, 2. e., parallel
to the molar contact. It is composed of the usual biotite gneiss
in which a thick sheet of hornblende-gneiss lies embedded,
making up most of its mass. The latter has itself the appear-
ance of being an eruptive rock which is thus older than the
porphyritic granite. Associated with it are a large number of
smaller biotite gneiss fragments which have no definite arrange-
ment, but make a confused medley of discreet masses in the
porphyritic rock. The whole looks like a huge flow breccia.
Rather more than a half mile further north on the same road,
there is a breccialike aggregation very similar to the last, even
to its containing hornblende-gneiss folded up in a large mass of
biotite-gneiss.

Three hundred yards west of where Dr. Dana's road leaves
the four corners at New Hampton Centre we note another of
those zones of transition between the porphyritic granite and
the schists in contact with it. It is some twenty feet wide, and
is strikingly similar in appearance to the case already described
at Centre Harbor. Here the schist is cut by intrusive tongues
with more or less sharp boundaries. These apophyses run across
the gneissic planes.

On the extreme eastern end of the Sandwich Mountains
at an elevation of about seven hundred feet above the Bear
Camp River, a remarkable flow breccia or ‘‘ permeation aed
outcrops in some extensive pasture fields. The rock presents
all the features of a plutonic flow. The horses are here almost
entirely hornblende-gneiss, some of them massive, both fine-
grained and coarse-grained, others distinctly schistose. The
porphyritic granite is on the whole granitic in appearance, but
at the boundaries of the fragments, the feldspar phenocrysts are
often oriented about them in a way which is strongly suggestive
of a flow structure. The usual trendless nature of its constitu-

* Barrow, Q. J. Geol. Soc., 1893, p. 331.

SOKCAULILIEID LAOS AE NABH TTA” (EINEMS Ss (OVE INP EWE AAA ES BK ID ANE

ents is also lost in some of the tongues of porphyritic granite
which penetrate the fragments in all directions. There the
minerals are pulled out in planes parallel to the walls of the
intrusion. The source of the hornblendic inclusions was dis-
covered within a hundred yards of the breccia. An unknown
thickness of the hornblende-gneiss lies interbedded in the
biotite-gneiss. This great breccia outcrops at several places
through a distance of three hundred yards along the base of the
mountain and is only one hundred yards from the massive
terrane of the Montalban group, which is continuous all the
way from Morgan Mountain.

These occurrences of hornblende-gneiss in the porphyritic
granite throw light upon the ‘‘hornblende rock ” which was noted
by Hitchcock in the Survey Report* as occurring to the east of
Wickwas Pond. It covers altogether about an acre in extent.
The rock is a hornblende-gneiss closely related in composition
to the masses already described. It has a strong schistosity
which lies parallel to the foliation of the granite enclosing it.
The latter sends intrusive tongues into the gneiss which is
evidently a large floe of the country rock moved far from its
original source.

The small oval area of the porphyritic granite on the top of
Mount Prospect is a stocklike body which suggests from its
position an intrusive origin. Field study confirms this opinion.
The rock is typical of the porphyritic granite in composition, in
grain, and in the size of the phenocrysts. Within this por-
phyritic granite there are embedded several horses of the sur-
rounding Montalban schists. The latter are extensively crum-
pled, perhaps by the intensity of the granitic intrusion. Again
one can notice the parallelism of the phenocrysts to the margins.

The porphyritic granite in contact with the Rockingham muica-
schist— One of the most important localities in the state to
suggest an intrusive origin for the porphyritic granite is on
Saddle Hill, where that rock comes in contact with the Rock-
ingham mica-schist. Here the formation is composed of well-

tVol. II, p. 594.

716 REGINALD ALDWORTH DALY

foliated, fine-grained, muscovite-biotite-schist with abundant
mica. The molar contact is found on the eastern end of the
hill. It strikes N. 25° W., and is parallel to the schistosity of
the mica-schist and to the pronounced foliation of the por-
phyritic granite. All the structure planes dip westward at a
high angle. Going across the strike from the contact toward
the porphyritic granite a remarkable series of elongated
horses of the schist interrupt the continuity of the granite.
They are usually much longer than their width, as, for example,
a large one 150 feet long by 35 feet wide, which appears on the
west side of the saddle. In most cases there is a definite ori-
entation of the horses parallel to the contact line, while the
foliation of the porphyritic granite wraps around the inclusion
in a significant way. They are uniformly schistose with that
structure as well developed as in the main body. Crumpling of
the horses is also characteristic. For about two hundred yards
east of the contact, the schist is cut by several intercalated
sheets of porphyritic granite, varying from five to ten yards in
thickness. Their phenocrystic feldspars lie parallel to the walls
between which the sills were intruded. Similar sheets can be
found in the pasture on the southern flank of the hill and west
of Randlett Pond.

Relation of the porphyritic granite to the Waterville eruptives.—
It is probable that the porphyritic granite is older than all of the
intrusive rocks of the Waterville Mountains. The contacts were
discovered in only one place, namely, on the southern slope of
Mount Whiteface; there the hornblende-granite composing the
mountain distinctly cuts the porphyritic granite. In the path
from the Elliott House, at Waterville, to the top of the Sand-
wich Dome, many outcrops of several types of granitic rocks
present a problem of correlation which the writer has had no
opportunity to solve. It is possible that these rocks are chilled
phases of the Conway granite; for there is, in the main, a ten-
dency towards a porphyritic structure throughout, which on “the
one hand becomes more pronounced as one approaches the por-
phyritic granite, and is entirely lost in the very coarse Conway

SO-CALLED PORPHYRITIC GNEISS OF NEW HAMPSAIRE 717

(hornblende). granite in the bed of the Mad River. If this
hypothesis be correct, the Conway granite is younger than the
porphyritic granite, for at about 1800 feet above the river the
porphyritic phase distinctly cuts the coarser rock.

The Ashuelot area—The country rock about the porphyritic
granite of the Ashuelot area is referred by the survey to three
different formations. the Bethlehem gneiss, the schists of the
Coés group and the Montalban group. Specific reference to this
area was made in the second volume of the Survey Report. In

3P, 470.
their general correlation, the survey considered the markedly
oval form of this and other occurrences of the porphyritic
granite as allying it in point of age to similarly shaped masses
in the Archzan elsewhere. Such a form has a nearer homo-
logue to the batholites described by Emerson in western Massa-
chusetts, and as we shall see, these similar forms have similar
origins. That the porphyritic granite of the Ashuelot area is
eruptive and of an intrusive nature can be amply proved. We
shall not attempt to trace the evidence from the contact-
phenomena, as it might be traced in a complete description of
the whole boundary. It is of the same nature as that outlined
for the Winnipiseogee area. With that fact in mind, we have
considered it expedient to refer to a few only of the possible
localities which can be readily visited for confirmation of our
views.

A representative contact of the porphyritic granite and
Coés mica-schist outcrcps where the boundary line between them
crosses the road running southwest from Ashuelot over Gun
Mountain. Here and along the western ridge of Gun Mountain
the typical biotite-muscovite-schist is strongly charged with
interbedded actinolite-schist and quartzite. Several apophyses
of the porphyritic granite cut the schist. One of them, twenty
feet wide, cuts across the strike, extending a considerable
distance from the contact before it disappears under the soil-
cap ; another over two feet in width is also well exposed, but lies
nearly in the planes of schistosity. Horses of schist are embed-

TS REGINALD ALDWORTH DALY

ded in the granite, but the overlying loose deposits prevent the
discovery of any definite arrangement among them. The
granite itself has a good parallel structure, and it is important to
note that its structure-planes are conformable in strike and dip
with those of the adjacent schists. This same conformity was
several times observed along this western side of the area.
Sometimes, even at the contact, the porphyritic granite is quite
granitic without a trace of the foliated structure. A good
example of this appears at the contact on Hall’s hill, near
Chesterfield factory. At this locality, too, there is no doubt as
to the relation of the two formations. The intrusive tongues of
porphyritic granite cut across the schists and associated gneissic
bands in a very marked way; the sharp contrast of grain and
composition enabling one easily to differentiate the igneous
masses. Occasionally dikes of the porphyritic granite may be
found traversing the schists at a distance from the contact. At
the three corners, about a mile south of Chesterfield, numerous
great veins of coarse pegmatite outcrop and with them occurs a
set of true porphyritic granite dikes which are probably apophy-
ses of the main mass, half a mile away.

Facts of like character refer to the contact with the Beth-
lehem gneiss on the eastern side of the oval. Field evidence
shows that the latter is of the same metamorphic epoch to which
the Cods mica-schist is referred; thus, the argument regarding
the better exposed part of the boundary applies to it in its
entirety.

Fitzwilliam area.—We have seen already that the survey
suspected an eruptive origin for certain parts of the porphyritic
granite, and had cited facts,from the Fitzwilliam area as in part
the basis for the conception. The contact line of this little patch
of the rock is very clear in its teaching. Even more graphic
than that of the bowlders described in the survey report*is the
evidence where the rock is in place. About a mile southwest
of the village the porphyritic granite is found in a pasture field
by the roadside. Included in it are many horses of biotite-

Vol. II, p. 471.

SO-CALLED PORPHVRITIC GNEISS OF NEW HAMPSHIRE 719

gneiss, some of which are large, being as much as twenty-five
feet in diameter. Within one of the latter an interesting irregular
injection of the porphyritic granite is well exposed. One
feature exceptionally well shown is the fine-graining along the
margins. At this place, too, dikes of the Concord granite cut
the porphyritic granite, and the former rock is thus the youngest
terrane in the region. Since it surrounds the porphyritic granite
on all sides, this Fitzwilliam occurrence may itself be a large
floe brought up from below from a much larger mass.

The Main area—Our observations on the Main area were
extended only to its southern half. The great thickness of the
various glacial deposits make it, on the whole, less satisfactory
for a study of contact relations than the Winnipiseogee area.
We have aimed in the course of a somewhat hasty examination
to discuss the facts as regards the schists grouped by the survey
under the names of the ‘“‘Ferruginous slates,” and the ‘“ Ferru-
ginous schists.” In both, the rocks consist of two-mica-schists,
biotite-schist, biotite-gneiss, and muscovite-biotite-gneiss, all of
which may be garnetiferous. Between them we can trace no
definite distinction, either of composition or of age, and the area
on the eastern border, marked ‘‘Lake Winnipiseogee gneiss,”
encloses stripes of schistose rocks which are identical with those
of the above-mentioned groups. Here, as often elsewhere, the
grounds for the subdivision carried out by the survey do not
appear in the field.

The great sill of porphyritic granite to the north and north-
east of Greenfield has one contact well exposed with interrup-
tions for the distance of amile. It is an intrusive one. The
granite was erupted into the schists along a plane of foliation,
and there is the usual development of parallel structure in many
of its outcrops which accords with that of the walls. The
intrusion is, on the whole, sheet-like in its form, though in some
places where the schists are intensely folded, it cuts across their
structure-planes. In such cases the foliation of the porphyritic
granite remains parallel to the boundary line. The apophyses
penetrate the schists irregularly in all directions, generally pay-

720 REGINALD ALDWORTH DALY

ing no attention to planes of weakness. They are finer-grained
than their parent sill, but show here and there a feldspar as much
as two inches in length.

One of the most interesting parts of the contacts is that
which belongs to the area marked ‘‘ Lake Winnipiseogee gneiss”’
by the survey in the towns of Antrim and Hillsboro. It is
exceptionally well exposed at intervals for a distance of five
miles, and especially on the long ridge some two miles west of
Antrim. The name thus given the rock with which the porphy-
ritic granite here comes in contact is a decided misnomer. The
new terrane consists of an ancient metamorphosed eruptive cut-
ting the ‘“‘Ferruginous” rocks in every way similar to the schists
that extend from Bennington to Henniker. This complex is
itself cut by the porphyritic granite.

The older eruptive rock is a typical coarse granitite containing
a good deal of muscovite which is all secondary. The quartz is
the common blue variety of New Hampshire crystallines. Both
orthoclase and a basic plagioclase occur, but they are generally
badly decomposed. It is a difficult rock to diagnose thoroughly
on account of the vast amount of crushing which appears in the
thin section. The quartz and feldspars ge much granulated
marginally, the unbroken cores showing the characteristic wavy
extinction. The plagioclase lamellae are often bent through
large angles. Minute faulting is common in them, and through-
out the slides the shreds of biotite are bent and twisted in a
striking manner, while the extinction on the base of biotite
plates is most irregular. In fact the condition of this rock is in
marked contrast with that of the porphyritic granite close by.
The granite is quite without any signs of serious disturbance; the
granitite has endured the very severe mechanical strain of
extensive mountain-building. Often the signs of developed
schistosity in this once massive rock are easy to discern in the
ledges, and these new structure planes strike a few degrees east
of north, z.e., they lie in the main parallel to the strike of the
Fenrucimous e tetrante:

Now, within the crushed granitite there is an extraordinary

SO-CALLED PORPHYVRITIC GNEISS OF NEW HAMPSHIRE 721

display of inclusions, varying in size from small fragments to
masses twenty feet square, all of which have evidently been
derived from the older schists to which they are mineralogically
and structurally similar. These horses are highly ferruginous,
and weather with the same rusty appearance that characterizes
the parent rock. So great is their number in some places that
considerable stretches are veritable flow breccias. But it is
rather the remarkable crumpling and other evidences of intense
folding which attract one’s attention to these outcrops. The
sliverlike horses are very often bent into sigmoid flexures;
sometimes one is seen to be completely doubled back on itself
in a nearly closed fold. They are usually much jointed, and
here and there actual movement along a fault plane may throw
one part of the inclusion a foot or more out of its normal con-
tinuity. While there is not much difference mineralogically
between these inclusions and the rock of the ferruginous terrane,
yet there is some evidence of a metamorphic change due to the
granitite. About one of them, some two feet long and a foot
and a half broad, in particular, a two-inch zone filled with large
biotites was developed. The biotite of the granitite itself is
often segregated in large individuals. Many of the horses have
been considerably melted up, and it is probably the absorption
in this way of so much of the iron oxides that conditions the
characteristic deep reddish brown color of the weathered granitite.

This terrane has but few affinities with the simple Lake
Winnipiseogee mica-gneisses, where they occur in their normal
fresh uncrushed habit. No evidence is yet forthcoming that the
latter are eruptive. Not only do these multitudinous horses
prove the eruptive origin for the granitite, but its actual contact
with the ferruginous schists was found on Riley Mountain, and it
tells the same story. The usual field criteria of the presence of
horses, apophyses, and intrusive sheets are there exhibited. A
rock zone of the foregoing description, averaging rather more
than a quarter of a mile in width, runs southward five miles to
the Antrim ridge above mentioned, always appearing between
the porphyritic granite and the main body of schists.

722 REGINALD ALDWORTH DALY

At many places along its western margin the porphyritic
granite cuts the granitite, but often passing into it by a zone of
transition analogous to those described in the Winnipiseogee
area. Thus we have added another to the crystalline terranes
which have been profoundly affected by dynamic processes since
their formation; they are in this respect to be contrasted with
the younger relatively unaltered porphyritic granite, and lastly,
they are of interest not only from their relation to the history of
igneous activity in the state, but also from the light that they
throw on the age and origin of the granite.

REGINALD ALDWORTH DALY.

(To be continued.)

te vw A SURE MENT OF FAULTS:

AccorDING to the definition given by Dana, “ faults are dis-
placements along fractures.”” Whenever the rocks of the earth’s
crust are subjected to strain, fractures take place in them as in
any other body under similar conditions, and the different parts
of the rock tend to move past one another along the fracture-
planes, seeking to obtain relief from the strain and to accommo-
date themselves to new conditions. In this movement one part
of the fractured rock-mass may move upon the other in any
direction, up, down, sidewise or obliquely, according to the
conditions, which are different in each instance. There is, so
far as I know, no law governing the direction of movement in
faults which is of any use in geological diagnosis. Naturally,
when there is any preéxisting plane of weakness of the rock
which is subjected to strain the movement takes place by prefer-
ence along this plane; and, hence, in sedimentary beds, it is
probable that movements along the stratification planes consti-
tute the commonest variety of faults. Inasmuch, however, as
the beds in disturbed districts lie in every conceivable position,
the probability just stated does not give any clew to the average
attitude of faults.

The movement in faults can be completely ascertained only
by the aid of independent and accidental phenomena. In homo-
geneous rock-masses (leaving out of consideration fault scarps,
fault gulches, and other topographic phenomena, and treating
the faulted mass as a solid without boundaries), the amount of
movement cannot be ascertained or even approximately esti-
mated; although the exzstence of a fault can be determined by
the records left on the slipping surface or surfaces in the shape
of ground-up rock or fault-breccia, in polished and striated rock
faces, and so on. It is certain, however, that the amount of
friction as displayed by trituration and polishing is not neces-

723

724 J. EDWARD SPURR

sarily proportionate to the amount of movement, since faults
with slight displacement are often accompanied by zones show-
ing profound trituration, while others of far greater movement
show to a much less degree the effects of friction. The friction
in each case seems to depend upon the angle of the chief stress
to the sliding plane, rather than on the amount of movement
along this plane. In heterogeneous rocks the amount of move-
ment of a fault can ordinarily be estimated with more or less
accuracy, the degree of closeness depending upon the nature of
difference in the composition of the rock-mass. In such heter-
ogeneous rocks the amount and direction of a fault movement
must be judged by any available phenomenon or phenomena.
By far the commonest variations in rock-masses which are con-
stant enough to be reliable as data are sedimentary beds, and
therefore the commonest means of measuring a fault movement
is the separation of the two parts of an originally continuous
stratum. On this account it is easy to fall into the error of
considering faults simply as dislocations of strata. In careful
geological work, however, such as mining work must necessarily
be, it is important to cultivate a more correct conception, and to
regard sedimentary beds as phenomena accidentally associated
with faulting, whose dislocation must be associated with all other
available criteria, each one as valuable as the other, to deter-
mine the amount and direction of the total movement or dis-
placement. Any fault, for example, in which the direction of
movement is parallel with the plane of sedimentation will not
cause any apparent displacement in a sedimentary bed ; and this
may be the case in faults having any conceivable attitude, since
the sedimentary beds themselves may be folded so as to stand
in any conceivable attitude with reference to any fixed plane,
such as the earth’s surface.

When the direction of movement in a fault lies at a slight
angle to the plane of sedimentation, the apparent displacement
of a stratum resulting from this fault will be only a slight part
of the actual fault movement; and it is only when the direction
of movement is perpendicular to the plane of sedimentation that

THE MEASUREMENT OF FAULTS 725

the separation of the parts of the faulted stratum is an accurate
measurement of the movement. Theoretically speaking, the
chances are infinitely against any such coincidence, and in actual
practice it is rare that the movement may be even approximately
estimated in this way. In mining geology it has been found
that the most valuable criteria for measuring faults are, besides
sedimentary beds, igneous bodies, such as dikes ; bodies of ore ;
striz on the fault plane, showing the direction of movement ;
and the composition of the fault breccia, which may show, in
some degree, the amount of movement. By taking several of
these criteria together it is often possible to actually ascertain
the movement of a fault.

It is sometimes possible to find out the amount and direction
of movement immediately ; but more often it must be indirectly
calculated, and to do this it is important to have clearly in mind
the nature and value of some of the principal functions of a fault
movement, and to have specific terms by which to designate
them. The terms already in use are of a rather vague and gen-
eral character, resulting from the usual conception of a fault as
a dislocation of strata; the four generally employed are ds-
placement, throw, heave, and offset. Vhe words displacement and
throw are used interchangeably, and commonly refer to the
separation of beds by a fault as seen ina vertical section. Each
of these terms is used by some to indicate the distance along
the fault plane between the broken ends of the bed as seen in the
section, and sometimes the perpendicular distance between the
parts of such beds, projected, if necessary. There is no agree-
‘ment, however, which definitely assigns the terms to separate
measurements, and, indeed, it is very common for a writer to use
the terms interchangeably for one or the other function. Heave
and offset are also used interchangeably, and are usually held to
signify the perpendicular distance measured on a horizontal
plane, such as the earth’s surface, between portions, projected,
if necessary, of a bed separated by a fault.

In mining work it is generally necessary to clearly differen-
tiate the different functions of a fault movement, and I have

720 ED VVATTO SO ihe

adopted the following terms descriptive of the most important
of these; these terms include nothing very novel in the way of
nomenclature, but are intended simply to affix definite names to
definite things.

Dislocation and displacement are general terms, applicable to
any part or the whole of a fault movement. Each of the func-
tions defined below, and to which specific names are given, may
be called simply a dislocation or displacement.

Total displacement is the distance which two points originally
adjacent are separated by the fault movement; the line connect-
ing these two points lies in the fault plane in all straight faults.
It is occasionally possible to determine the total displacement
directly by such criteria as the separation of the parts of an ore
body, the intersection of a given dike with a given stratum when
found on both sides of the fault, and in other ways; but ordina-
rily it can only be calculated or approximately estimated from
some of its more easily measured functions.

The lateral separation is the perpendicular or shortest distance
between the two parts of any continuous zonal body (such as a
sedimentary bed), which has been separated by a fault, the dis-
tance being measured along the fault plane. The lateral separa-
tion may be measured: in a vertical, horizontal, or oblique line,
according to the attitude of the bodies between which it is meas-
ured, and in any fault it may vary from zero to the total dis-
placement. In the case of dikes cutting sedimentary beds, of
marked unconformity, of abrupt folds, and so on, it may be pos-
sible to measure two or more lateral separations in a single fault.
In this case, and in a number of others which are possible, the
total displacement may often be calculated from the lateral
separation, since the latter is always the side of a right triangle
of which the former is the hypotenuse.

The perpendicular separation is the perpendicular distance
between corresponding planes in the two parts of any single body
available as criterion (such as a sedimentary bed), when this
body has been separated by a fault, the planes on each side of

the fault being projected for the purpose of measuring, if neces-

THE MEASUREMENT OF FAULTS 7PM

sary. The perpendicular separation thus has a certain relation to
the lateral separation; for it constitutes a side of a right triangle,
the hypotenuse of which is the lateral separation, except in the
possible case where the perpendicular and lateral separations
coincide.

This mathematical relation makes it often possible to estimate
the lateral separation from the perpendicular separation, and from
the latter the total displacement. Of these three functions, the
perpendicular separation is most easy of measurement, and its
value may vary from zero to the full amount of lateral separation.
The lateral separation is easier to ascertain than the total dis-
placement, and its value may vary from zero to the total displace-
ment.

The measurements which have been defined have no constant
direction, since they refer to fault movements which are capable
of infinite variation. In general geological work, however, it is
often only possible to measure fault movements along certain
arbitrary planes. The most valuable of these planes, are the
earth’s surface, which may be considered a horizontal plane, and
vertical sections, into which available data are put, with the gaps in
the chain of information often theoretically filled out. In such
cases, where some dislocation is evident, but the information is
so meager that it is not possible to know the fault so accurately
as to estimate even approximately its total displacement or lat-
eral or perpendicular separation, it is necessary to employ spe-
cific terms to designate the known or estimated dislocations,
although the relations of these dislocations to the total displace-
ment may be unknown. For this purpose the terms offset, throw
and vertical separation may be used. The terms ¢hrow and verti-
cal separation are applied to the dislocations of a fault as seen in
a vertical section; the term offsef to the dislocation as seen in
a horizontal section, such as the earth’s surface may be con-
sidered to be.

A throw may be defined as the distance between the two
parts of any body available as a criterion (such as a sedimentary
bed), when these parts have been separated by a fault, the dis-

728 J. EDWARD SPURR

tance being measured along the fault plane as shown in a verti-
cal section.

The vertical separation is the perpendicular distance between
the intersection of the two parts of any faulted body available
as a criterion (such as a sedimentary bed), with the plane of a
vertical section, the lines of intersection being projected if neces-
sary for the purpose of measurement. In perpendicular faults
the vertical separation is identical with the throw; in all others
it is less than the throw, but sustains a certain relationship to it,
being one side ofa right triangle of which the throw is the hypote-
nuse. Thus the vertical separation may vary from zero to the full
amount of the throw. The throw is always a part of the total
displacement, although with no definite relationship to it, and
varies from zero to the full total displacement.

The term offset may be used to designate the perpendicular
distance between the intersections of corresponding: plane in
the two parts of any faulted body available as a criterion, such
as a sedimentary bed, with a horizontal planes such as the
earth’s surface may be considered to be; the planes being pro-
jected for the purpose of measuring, if mecessary. like the
throw, the heave or offset is a part of the total displacement, but
has no definite relationship to it.

Tosum up, there are six terms proposed to designate the differ-
ent parts of a fault movement, each term applying to a measure-
ment which varies in accuracy and proximity to the total dis-
placement in proportion to the available amount of information.
For general outline work where accurate data are not obtainable,
the terms “row and vertical separation, referring to the measure-
ments of a fault at its intersection with a vertical plane, and the
term offsef, indicating a measurement of a fault at its intersection
with a horizontal plane, are adopted. The throw and offset are
parts of the actual fault movement, but of unknown value, while
the vertical displacement sustains a certain relationship to the
throw. Where more complete data are obtainable, the terms
total displacement, lateral separation, and perpendicular separation are
adopted. The perpendicular separation sustains a certain rela-

THE MEASUREMENT OF FAULTS 729

tionship to the lateral separation, as the lateral separation does
to the total displacement.

The terms which have been adopted above have purposely
been made as few as is consistent with the plan of furnishing a
scheme for complete fault-analysis. The number might be
increased indefinitely ; yet ordinarily this is undesirable, for most
other fault measurements are simple mathematical functions of
the terms above adopted, and can be easily reduced to one of
these; and the great multiplication of terms leads to confusion
in a study which is at best not too simple. In specific instances,
however, it may be desirable to increase the number of terms, and
to give separate names to other fault measurements.

J. EDWARD SPuURR.

1503, INUIT VAINID GeQIOGIC. WuUMes,,

ASSUMING the correctness of the ice-sheet or glacier theory
of the origin of the drift which, according to one supposed to
be of high geological authority,’ ‘‘has passed from the region of
hypothesis to that of demonstration, and should form the basis

b

of all reasoning on the subject,” there are still many problems
that are open to discussion and in regard to which writers widely
vary in their opinions and statements. One of these is the lapse
of time between the beginning and the end of the period, that
portion of geologic time required to prepare for and lay down
the drift deposits and to return to present climatic and physical
conditions. Of late years there has been a tendency in some
quarters to reduce the estimated length of this period. Accord-
ing to Prestwich? 25,000 to 35,000 years would suffice for the
whole period of formation and retreat of the ice-sheet. Pro-
fessor Wright endorses this estimate,3 and Warren Upham‘ even
abbreviates it a little, allowing only 20,000 or 30,000 years for
the actual glacial period, and 6000 to 10,000 years for the since
intervening time. Becker,> figuring on astronomical data, thinks
that conditions favoring the glaciation of the territory covered
by the drift may have existed within 40,000 years, and presum-
ably gives that as the probable outside figure for their occur-
Re meee

On the other hand, perhaps the larger number of glacialists
have allowed in their estimates very much longer periods. To
say nothing of Croll, Ramsay, Geikie, and earlier writers, we

™Geol. Mag., new ser., Decade IV, Vol. IV, 75, February 1897. (Review of
Croll’s Life and Work.”)

2“ Geology,” p. 534, 1888.

3 Man and the Glacial Period, p. 364, 1895.

4Bull. Am. Geol. Soc., V, 99, 1894.

5 Am. Jour. Sci., 3d ser., XLVII, 95-113.

730

Lae ite bh AND GEOLOGIC TIME 731

have, amongst recent writers, R. Bell,t who thinks the estimates
of the above-mentioned authors mot excessive. Chamberlin?
estimates the lapse of time since the Kansan epoch to be equal
to fifteen times the lapse since the last epoch, which would give
a high figure for the whole period on any tenable estimate of
this last factor, and to this is to be added an undetermined num-
ber of years for the pre-Aftonian (Albertan ) stage., -Penck, at
the recent Toronto meeting of the British Association, is reported
to have allowed at least 500,000 years for the glacial epoch,
including all the interglacial stages, and very secenitly Be
Taylor,3 in an article on the moraines of recession of the latest
(Wisconsin) ice-sheet, gives as his estimate of the time required
for the retreat of this single ice invasion from the latitude of
Cincinnati to the straits of Mackinac, a period of from 75,000
to 150,000 years. Adding to this an equal lapse of time for its
advance, and we have an estimate of 150,000 to 300,000 years
for the whole time occupied by this most recent member of the
drift.

In addition to the actual periods of the ice occupancy of the
territory we have to reckon in the interglacial epochs of which
there is considerable evidence, and which must materially add
to the length of Pleistocene time. I have not seen many esti-
mates of the time required by these, the most noteworthy cne
being that of Professor McGee, of the time required for the
deposition of the forest bed overlying the earlier Iowa till.
Taking for his unit the period of written history, the very
least figure he gives for this formation is about 112,000 years,
and this is far exceeded by his estimate of its possible maximum
duration. The thickness of some of these intercalated beds
would naturally indicate a considerable period for their deposi-
tion, but McGee’s estimate certainly seems an extreme one, and
is the more noticeable when considered in connection with the
relatively very short allowance of time he has given for the ice
invasions themselves, even allowing, as we should, that he is

* Bull. Am. Geol. Soc., I, 295. 3JouR. GEOL., V, 1897, July-August.

2Jour. GEOL., IV, 875, 1896.

Wie H. M. BANNISTER

considering only the peripheral portion of the ice-sheet and not
its greatest development. The length of the interglacial epoch
must in any case enter as a very important element in our esti-
mates of the total time required for the deposition of the driit,
and the limited data from exposures are at best more suggestive
than definite in the information they convey as to this point.

With these divergent views as to geologic time it would not
appear as if the glacier theory afforded a very satisfactory basis
for reasoning upon this particular phase of the subject. There
certainly seem to be decided difficulties in utilizing the drift
phenomena for the measurement of geologic time, each appar-
ently possible solution of the difficulty seeming to present still
more impossible problems. Some of the estimates made appear
to be compromises, therefore, or alternatives, accepted only as
better than something else. Thus Prestwich and Wright find it
easier to limit the duration of the glacial period than to admit
the possibility of man having existed 80,000 years on the earth,
or that the fauna or flora of today could possibly be the same as
that of 240,000 years ago. The elements of individual prepos-
session and mental idiosyncrasy enter largely into the considera-
tion of scientific questions, and all the more into such as this
where the chances of legitimate difference of opinion are
so ample.

It is the object of this paper to call attention to the method
of calculating geologic time by the transportation of erratics, a
method that has up to the present time hardly received the
attention, it deserves im the literature of they subjects a liteissat
first sight a little remarkable that this should be the case. That
some at least of those who have alluded to it appear to have dis-
credited its value is also remarkable, as any method that adds
any degree of certainty to our estimates ought to be regarded
as a boon to science. While, as I shall attempt to demonstrate,
it has its value even with the rather indefinite notions we have
hitherto had as to the flow of continental glaciers, recent
researches by Chamberlin and others on the Greenland ice-sheet
have added very much to its importance and applicability. We

THE DRIP i AND GEOLOGIC TIME WAS

have by it at the present time the data which enable us to form
a definite minimum estimate of the time required for the depo-
sition of the drift in North America, on the presumption that
this was done through the agency of land-ice, or glaciers. If it
is assumed that the drift was water laid, either altogether or to
any considerable extent, altogether different elements enter into
and affect the calculation, but that is not the assumption of the
present paper.

It is perhaps conceivable that the climatic conditions during
the formation of the ice-sheet were such that it was deposited
by precipitation simultaneously over the greater part of the
area it occupied. The névé, in other words, might have been
almost coterminous with the glacier, only a narrow external rim
being excluded. The evidence, however, of motion throughout
at least the greater part of its extent is afforded by the erratics
many of which have traveled 600 or 700 miles or even more
from their original beds. A bit of jasper conglomerate found
south of Cincinnati must clearly have traveled from the north
shore of Lake Huron, and fragments of Archean or eruptive
rocks found abundantly along the southern limit of the drift in
Illinois could have had no nearer source than northern Wisconsin
500 or 600 miles away, if indeed they have not a still more north-
ern origin. A bowlder or pebble from the north shore of Lake
Superior, if found in southern Illinois, would have traveled nearly
or quite 800 miles, and while Iam not sure that any such have
been identified, their occurrence there is altogether within the
bounds of probability. Such erratics, according to the glacier
theory, must have been conveyed as subglacial or intraglacial
detritus and must have progressed with the ice certainly at no
greater rate than the ice itself and almost certainly at a much
slower one. We have no certain evidence what the progress of
the glacier was, but it could not have beena rapid one. In exist-
ing glaciers the most rapid rate of motion is about seventy-five
feet a day, but this occurs only during one or two months in
summer, and in two or three exceptional Greenland glaciers
where the ice,so to speak, is under pressure down a favorably

734 H. M. BANNISTER

inclined valley from the great Greenland ice-cap, the nearest
analogue to the immense glaciers of the drift period with which
we have at present any satisfactory acquaintance. These rapid
flowing glaciers are exceptional in Greenland, where the general
movement of the ice is unquestionably very slow. They can be
compared to rapids at the outlet of a lake. The Greenland ice-
cap far overtops the bordering mountains, and yet in only some
seventeen places along the whole Danish Greenland coast are
there free outflows to the sea. While we know less of the other
portions of the coast the general character is the same; a rapid
motion is exceptional and it is a reasonable certainty —to quote
Taylor’ whose paper contains the latest discussion on this ice motion
—‘‘that the average movement of that portion of the border of
the Greenland ice-cap that rests upon the land is extremely small.
Of that portion which ends in the sca only a small fraction has
a high rate of motion, as is shown by the lack of activity in the
discharge of icebergs. When it is considered that the land
border is very much greater than the sea border, and that of the
sea border a portion has a relatively slow movement, it will be
evident that the average rate of movement of the great ice-sheet
of Greenland cannot be high; and the average rate of this border
is the nearest available analogue to the border movement of the
still more extended periphery of the ancient American or Lauren-
tide glacier.”

In fact it is impossible, when we consider that the Greenland
ice-cap only abuts on the sea along a small portion of its border
in the form of glacial tongues, and that the average movement
of these is so small, not to believe that towards its interior the
ice movement must be almost imperceptible—almost if not
absolute stagnation. The Antarctic ice-cap is very little known
to us, but its movement must also be very slow, judging from
the discharge of icebergs. All the icebergs of the North Atlantic
come practically from a few Greenland glaciers, making up
altogether only a minute fraction of the whole Greenland coast.
In the Antarctic, on the other hand, we know of hundreds of

tJourR. GEOL. Vol. V, 442, 1897,

LHE DWkRT AND GEOLOGIC FIME 735

miles of continuous ice cliffs ending directly in water hundreds
of fathoms deep, and have reason to believe that this is only a
fraction of what exists, and yet icebergs are sometimes almost
unknown in the southern seas for years at atime. Again there
will be years in which they are abundant and extraordinary in
size, but at no time is their quantity comparable to what ought
to exist were the discharge anything like a free one along the
barrier.‘ It can be reasonably assumed, therefore, from what we
know at present that the movement of the southern ice-cap is
also extremely slow, notwithstanding the favoring conditions
of direct discharge into deep water.

Yhe great Laurentide glacier, extending over four million
square miles of surface, can also be safely assumed to have hada
very slow motion as a whole, fully as slow as that of the Green-
land or southern ice-cap. In fact the question arises, and is not
at first sight readily answerable, how it had any motion at all.
Gravitation certainly had less play than in Greenland, for instead
of an area nowhere more than three hundred miles from the
ocean * we have one eighteen hundred or two thousand miles in

t** As has already been stated, there are years of very few or no icebergs, and then
years when great numbers are reported. In the year 1832, the southern ocean was so
covered with icebergs that a number of whaling vessels, bound round Cape Horn,
encountering them, put back to Valparaiso to await a more favorable season, because
it appeared too dangerous to undertake the voyage. Again in 1854 there was a great
accumulation of icebergs, and now during the past few years, notably 1892 and 1893,
there has been another notable output from the great berg factories of the Antarctic
regions. During the intervals between these periods there have been very few bergs
reported. What causes this occasional great accession of bergs? Some authorities
offer as a probable explanation the breaking off of the ice margin by volcanic erup-
tions, and others that earthquakes cause numerous pieces of the glacier to become
detached and set adrift as icebergs, and others that unusual heavy annual snowfall
is favorable for increase in number of bergs. The rapidity of glacier movement seems
usually to regulate the number of bergs cast off. If the ice at the bottom of the glacier
moves so slow that the melting of the margin on coming in contact with the salt water
equals the advance, then we would have no icebergs, except perhaps those breaking
off from the upper part of the outer margin, and these would be comparatively small.”
W.T. Gray, M.S. U.S. Hydrographic Office, Pilot Chart, N. Pacific Ocean, Novy.
1895.

‘Prof. Chamberlin finds no evidence that the ice-sheet of Greenland ever very
greatly exceeded its present limits.

730 H. M. BANNISTER

diameter and one in which no reasonably supposable elevation
could give a uniform slope varying appreciably from the hori-
zontal. An elevation at the center of radiation of ten thousand
feet (which is much beyond the most favorable interpretation
which any known data will bear) with an ice-cap of as much more,
would only make a slope of under half a degree in eight hun-
dred miles, and of considerably less in some directions to the
outer limits of the ice. Some glacialists, however, are liberal in
their allowances of earth movement to account for the flow of
the glacier. Mr. Upham," for example, thinks that the strong
current needed to transport bowlders from the southeast shore
of Hudson Bay one thousand miles southwestward to southern
Minnesota, would require a slope of at least fifty feet or more
per mile, apparently unmindful of the fact that such a slope for
the given distance would require an elevation of the ice-cap to
the height of 50,000 feet, where precipitation would, if it
occurred at all, probably be so slight as to seriously embarrass
the formation of any considerable ice-cap whatever. It is not
probable, however, that there was any uniform slope over the
glacial field, and whatever effect was produced by gravitation
could not be such as would cause a rapid motion of the ice,
“faster than the Swiss glaciers.”* The other theories that have
been invoked for the glacier motion, the effects of thawing and
freezing, expansion under varying temperatures, etc., are none
of them, we think, counted as sufficient to cause rapid movement
in so large a mass, as a whole, even by their upholders, and such
estimates as two to five feet per day are hardly based upon a
due consideration of the probable or possible physical condi-
tions. Dana’s? estimate that ‘the rate of motion could hardly
have exceeded a foot a day, and may have been in most parts
no more than a foot a week”’ is much more likely to be near the
truth. Ice, except under special conditions of pressure or vis a
tergo, barely moves ona slope of one degree, and an average slope
"Greenland Ice Fields and Life in the North Atlantic, p. 304.
°? WARREN UPHAM. Bull. Geol. Soc. Am., III, 401, 1892.

3 Geology, 3d ed, p. 539.

THE DRIFT AND GEOLOGIC TIME EU

of a quarter of a degree for a thousand miles would require an
elevation at the point of origin of the flow of something approach-
ing five miles. The probability, and we may say the certainty, is
that the slope was not uniform and that over large distances the
ice traveled over dead levels, and in parts even stagnated, the
upper part flowing over the lower débris-laden portions. That
the contained débris has a retarding influence on the flow of
glaciers has been urged by O. P. Hay," I. C. Russell,? and R. D.
Salisbury,3 and it appears that this may even cause absolute stag-
nation under some circumstances. Even detached erratics seem
to progress more slowly than the body of the ice in certain
instances; witness the well-known observation of Professor W.
H. Niles# on the Aletsch glacier where ice moved so much more
rapidly than a contained bowlder as to leave a free tunnel fora
considerable distance on its lee side. Even lighter substances
appear to be occasionally retarded in their progress as compared
with the ice. Recognizable remains of buried travelers have
been taken out of Alpine glaciers even hundreds of years after
their loss.5 It is impossible, therefore, to claim that these errat-
ics could have traveled at the same rate as the surface of the
glacier, and when we consider that they bear the marks of hav-
ing been subjected to scouring in the ground moraine that has
left their surfaces flattened and striated, the probability of such
a rate of progression is certainly very much diminished.
Allowing a flow of two feet per day to the ice-sheet, which is
undoubtedly far above the real rate of the ice movement, it would
require 7200 years for Mr. Upham’s bowlder to travel its thousand
miles from Hudson Bay to southern Minnesota, and this with-
out any delay from friction or attrition in the ground moraine,
or stagnation in the lower strata of the ice. Taking, also, into
account the fact that the northern erratics are found at all dis-

tAm. Jour. Sci. and Arts, 3d ser.. XXXIV, 52, 1887.
2 Jour. GEOL., III, 823-883, 1895.

3 Jéid., Vol. 1V, 769-810, 1896.

4 Am. Jour. Sci., 3d ser., XVI, 367, 1878.

5 SIR HENRY HoworTtH. Geol. Mag. N. S., Decade IV, Vol. IV, 127.

738 Vals Wil JEAN INGE S ATI

tances from their point of origin and at all levels in the drift, it
seems sufficiently clear that we cannot measure the duration of
any single ice invasion by the period required for the transpor-
tation of a single erratic from its northern origin to its outer
verge, even allowing for all the retardation in the ground
moraine. Every one of the Archean fragments so commonly
seen along the southern borders or the drift must have required
some four thousand years, even if we allow it to have advanced
two feet a day, to reach its present. position and probably a
much longer period, for there is no good reason to suppose that
the mass of the ice-sheet itself advanced at any such rate. We
can also allow a somewhat more rapid transportation of débris
near the margins by floods, subglacial drainage, etc., and yet
find our time limit tending to be too small. The Alpine and
Scandinavian glaciers, with their steep gradients affording full
play to the action of gravity, move on an average only a few
inches a day. How the continental glacier derived its move-
ment, except at its elevated origin and near its periphery, is one
of the questions that no one has yet satisfactorily answered, and
the inevitable conclusion from the known facts is that while
motion undoubtedly occurred it must have been extremely slow.
The formation of the ground moraine must have required a
very prolonged period of time, involving as it did the grinding
up and working over of the rocks and other material that
together make up the till. It does not matter whether it is held
that it was mainly deposited under the ice-sheet by stagnation
of contained débris, as suggested by O. P. Hay,’ or as a contin-
uous terminal moraine as the glacier retreated, as was held by
Newberry.* In either case a long time must have been required.
In what has been said I have tried to show that a great ice-
sheet thousands of feet in thickness, extending over a third
of a continent, expanding from its center in the direction of
least resistance towards its periphery, having over the greater
portion of its area a very slight slope, and probably none at all
SILO, Cit
2 Geol. Survey of Ohio, Vol. Il, 29; III, 34.

DAE DRILL AND GEOLOGIC TIME 739

in parts; hampered by inequalities of the underlying surface
and by the detritus it shears off trom these, must have had. a
very slow, though irresistible, progress; and that, accepting the
existence of such an ice-sheet and taking account of this slow
rate of progression, the contained erratics, whose origin can be
identified by the situations in which they are found and the dis-
tances they have traveled, will afford a better means of making
an approximate minimum estimate of the duration of the Pleis-
tocene period than any other at our command. By this we can
assure ourselves with almost absolute certainty that a single ice
invasion could not have taken place carrying a single erratic
from north of the lakes to the southern limit of the drift in less
than four or five thousand years, and this without taking any
account of the time required for the change of climate, the
gradual gathering of the ice, its recession, the probable slower
motion of the erratics than of the ice mass as a whole, or its
retardation by friction, as evidenced by its facetted and striated
surfaces. Taking all these into the reckoning, we ought, it
would seem, to triple or quadruple the time; and if, instead of
taking the highest estimates of glacier motion, we accept the
more reasonable and probable ones, the period will be still more
prolonged. It is difficult to see how, under these circumstances,
a single ice invasion could have begun and run its course within
the limits of less than thirty or forty thousand years; and if we
accept Dana’s estimate of the glacier flow at one foot a day for
a maximum, and one foot a week as a possibility, we would have
to carry our figures very much higher. We have, however,
according to some of the highest authorities, Chamberlin, Lev-
erett, and others, five separate ice invasions to account for,
besides interglacial periods of possibly equal or greater duration ;
and this greatly magnifies the necessary estimate of time for the
whole glacial period. One of these ice invasions appears to have
transported bowiders one thousand miles, which, at the liberal
rate of two feet per day, would require 7200 years, and the
others, from the average extreme distance to which erratics were
transported, will equal certainly 500 miles, which would require

740 Jal Nile Sey IN UNI ESS TBI

3600 years, or, in the aggregate, 14,400 years. The total,
therefore would be, in round numbers, about 22,000 years for
the mere transportation of a single erratic in each invasion, and
that at an improbable rate of speed and without any allowance
whatever for the time occupied in the formation, culmination, or
retreat of the glacier, or for interglacial periods. It is suffi-
ciently evident from these figures that the ice-sheet theory of
the till formation is utterly incompatible with such estimates as
those of Prestwich and Wright, which give the whole glacial
period a duration of only 20,000 to 40,000 years.

It has been matter of surprise to me that so little weight has
been given by authorities to the arguments from the calculation
of the transportation of erratics in the estimation of the dura-
tion of the glacial period. Most of them absolutely ignore, or
at least fail to utilize it, and those who do allude to it at all,
like Helland,’ give it only the briefest and most casual men-
tion. It appears to me to be the one method by which we can
obtain, not the actual, but the utmost possible minimum of
duration of such an ice-sheet as the generally accepted glacial
theory demands.

Professor W. J. Crosby* has offered the suggestion that, as
the great mass of the rock débris of the till is local and has never
traveled far from its place of origin, the northern erratics were
transported largely by water in the glacial lakes that formed
along the borders of the ice-sheet. Inasmuch as these are found
throughout the till at all levels, his suggestion amounts practi-
cally to an admission that the whole mass in which they are dis-
seminated was thus deposited, which is altogether inconsistent
with the general tenor of his argument, and is almost, if not
quite, equivalent to giving up the land-ice theory of the deposi-
tion of the till:

It may be worth while here to notice one or two estimates
or statements in regard to the duration of certain stages of the
glacial period by prominent glacialists. The recent estimate of

t Zeitschr. der deutschen Geologischen Gesellsch. XXXI, p. 76, 1879.

2Am. Geologist, XVII, 1896, p. 234.

THE DINFT AND GEOLOGIC TIME 741

F. B. Taylor of from 75,000 to 150,000 years for the recession
of the Wisconsin ice-sheet from Cincinnati to Mackinac has been
already alluded to in the early part of this paper. As against
this apparently large, but possibly not too large estimate (that
is, admitting the land-ice formation of the Wisconsin drift), it
is interesting to quote Wright and Upham’s* dictum that ‘the
late divisions of the glacial period were far shorter than its
Kansan, Aftonian and Iowan stages,” and the estimate of Cham-
berlin? that makes the ratio of time to the present from the
earliest Wisconsin and from the Kansan stages as 2% and 15
respectively, leaving an undetermined figure for the still earlier
portion of the glacial period. That would make, according to
Taylor’s figuring of 150,000 to 300,000 years for the Wisconsin
invasion and retreat, a period of somewhere between 900,000
and 1,800,000 years back to the beginning of the Kansan drift.
These figures are, it is true, rather staggering, but it is not abso-
lutely necessary to accept the two estimates and combine them.
There may be other ways of reckoning the duration of the sepa-
rate stages of the drift. Certain it is at least that neither of these
authors is to be held responsible for the estimates of the other,
or the combination of the two.

In conclusion, the reasoning of this article may be summar-
ized as follows:

The estimates of the duration of the glacial period by promi-
nent geologists vary almost as widely as possible. It is probably
useless to attempt to obtain any approximate estimate of its
maximum duration, but we have in the transportation of erratics
a simple method by which an ultimate minimum of the time
occupied may be obtained. Accepting the land-ice hypothesis
of the deposition of the till, we must from all analogies, and all
our knowledge of glaciers and ice-caps, admit that the motion of
the ice-sheet was slow, and that it probably did not exceed a few
inches a day ; indeed, apart from the evidence of the till and its
contained erratics, it is hard to find any grounds for belief in its
motion over large proportions of the occupied territory. Erratics

t Loe. cit., p. 360. 2 Voc. cit.

742 H. M. BANNISTER

that are known to have been transported distances of from 500
to 1000 miles could not have traveled faster than the main body
of the ice, and must, as we know from the evidences they bear
of retardation and friction, have traveled much more slowly.
Even allowing the extravagant estimate of two feet per diem for
the ice movement throughout (and the recent investigations of
Chamberlin and others on the Greenland ice-cap have demon-
strated that this is an improbability) we can demonstrate that
a single invasion competent for the transportation of a single
erratic from its northern source to the southern limits of the
drift would have required a period of from 15,000 to 20,0Q0
years.* If we admit, as is more reasonable, that the average
ice motion was much less than this,—probably not over a very
few inches per diem, we will have to more than quadruple this
estimate. Taking into account, however, the inevitable conclu-
sion that the duration of a single ice invasion was not limited to
the conveyance of a single erratic or simultaneous group of
erratics, and that there were, in all probability, several of these
invasions with intermediate periods of sufficient length to allow
the development of extensive forests and the accumulation of
heavy deposits of vegetable mold, indicating a lapse of proba-
bly many thousand years, we are compelled to multiply the
above figures by an indefinite multiplier. The outcome in any
case is that the brief duration allowed for the glacial period by
some recent authorities is absolutely incompatible with the evi-
dence of erratics, according to the land ice or glacier theory of
the deposition of the drift.

tT have not in my argument taken account of the slowness of advance of the ice
border which must also be considered in calculating the total. Opposed to each year’s
advance there must have been a summer’s melting, and judging from the evidence of
the Greenland ice-cap, this latter element must have been of considerable importance.
The Greenland ice-sheet hardly gains at all upon the unoccupied land even in North
Greenland, the ice surplus all escaping by the few glacial outlets which are much less
active than those in South Greenland. In the case of the Laurentide glacier trench-
ing upon a fairly temperate region with a long summer, the estival melting must have
been quite marked. The additional transportation by flood torrents, etc., can be esti-
mated by the extent of the till deposits as compared with glacial striz, which even in

southern Illinois are reported as found on the underlying rocks nearly to the southern
margin of the drift.

THE DRIFT AND GEOLOGIC TIME 743

I have not attempted in this article to exhaustively discuss
the evidence of the slow motion of the ice in the Laurentide
glacier. Much more could have been said on that point, but any-
one who has followed the recently published studies of glacial
phenomena in Greenland by Chamberlin, Salisbury, and others,
will be able to supply most of the deficiencies in my argument.
The present paper is simply the statement of views that were
suggested by a consideration of some aspects of the glacial
theory as an amateur geologist.

I wish to also acknowledge here my indebtedness to Profes-
sor T. C. Chamberlin for valuable suggestions on certain points
here discussed.

H. M. Bannister, M.D.

CHICAGO.

ON Tis IIKI3 SJ INCIS Ol WIVOQUSIEIS MUAIT IC IOS SUL
MEDUSA IN 2th NIAGARA EIMESTONE
OW INOURINSUTIUN INCIVIONOUS 4

For more than a year past my attention has been directed to
some peculiar fossils from the dolomitic Niagara limestone of
northern Illinois, in the collections of Walker Museum at the
University of Chicago and of the Chicago Academy of Science.
The exact horizon and location from which the specimens were
obtained have in no case been recorded, but the general local-
ity for them all is Joliet, Ill. Additional specimens have recently
been secured from the excavations of the Chicago drain-
age canal, by Mr. L. H. Hyde, of Joliet, and these have been
kindly loaned for study.

The complete specimens of this peculiar fossil are disk-like
impressions, subcircular in general outline, with the periphery
lobed, and with the surface radiately corrugated or smooth. In
the center of the disk is a funnel-shaped depression and from
the center of this depression a stemlike process rises to about
the general level of the surface of the disk. The disk is divided
by four ridges, radiating at right angles from the center, into four
quadrants. The entire disk is rarely preserved intact, the larger
number of specimens being the separate triangular quadrants.
Several species are represented in the collection which differ in

t Just as this paper is going to press additiona] material from the collection of
Mr. E. E. Teller, of Milwaukee, Wis., has come to the writer, which throws a very
different light upon the nature of Cryptodiscus. One of the specimens in this collec-
tion shows a complete disk of Cryftodiscus situated at the summit of a tube composed
of plates which are arranged essentially as the plates in the anal tube of Callcrinus.
The evidence of these specimens seems to establish the fact that Cryptodzscus is a
remarkable disk-like expansion of the four plates forming the terminal ring of the
anal tube of some crinoid, probably Cadcrinws. Additional evidence for the correla-
tion of Cryptodiscus with Callicrinus is found in the fact that the genus Calhcrinus

occurs at every locality where Cryptodiscus has been observed. The specimens in
Mr. Teller’s collection will be illustrated and more fully described at another time.

744

FOSSIL MEDUSA IN THE NIAGARA LIMESTONE 745

the lobing of the periphery and in the ornamentation of the disk.
As in the case of most of the fossils in this formation, the actual
substance has been dissolved out leaving a mold in the rock,
and the specimens which have been collected are generally but
one side of a thin disklike cavity. None of the specimens have
been actually observed zm sztu, but it is believed that the speci-
mens usually collected, viz., those with the central depression
and elevation, are the lower sides of such cavities. The upper
sides are not so striking in appearance, and have usually not
been preserved by collectors. A few have been observed, how-
ever, and they differ from the lower sides in being nearly plane
over the central part, the funnel-shaped central depression with
the central stemlike process being absent. Figure A represents
diagramatically a cross-section of the fossil, cutting the disk
diametrically.

Fic. A. £f points upon the periphery of the disk. / the funnel-shaped depres-
sion in the center of the lower side. s the stemlike elevation in the center of the
funnel-shaped depression.

In examining the literature, two references have been found
to fossils similar to those under consideration. The first of
these is in the Twentieth Report of the Regents of the New
York State Cabinet of Natural History, where Dr. James Hall,
on Plate XJ, Fig. 18, gives an illustration of a similar fossil, also
from the Niagara limestone. No description of the specimen is
published further than the note in the explanations of the plate,
which is as follows: ‘‘The calyx of a Crinoidean? of a new and
peculiar type, for which I suggest the name Cryptodiscus.” No
locality for the specimen is given, but the species in the accom-
panying paper are all from southeastern Wisconsin or northern
Illinois.

Ata more recent date, in the Eighteenth Report on the Geol-

746 STUART WELLER

ogy and Natural History of Indiana, Mr. S. A. Miller has illus-
trated a single quadrant of a similar fossil from the Niagara lime-
stone at St. Paul, Ind. A short description is published, but no
name is given to it. - Mr. Miller states in his description that he
has seen a similar fossil from the Niagara limestone near Chi-
cago, circular in outline, and made up of four such segments as
he illustrates from St. Paul. The fossil he had in mind is doubt-
less one of those illustrated in the present paper.

Since the fossil to which Hall gave the name Cryftodiscus is
without doubt a form similar to those under discussion, his
name will be used in their description, although it has never
been properly published.

No satisfactory explanation of the nature of Cryptodiscus has
been given by either Hall or Miller. Hall’s statement with a
query, that it is the calyx of a crinoidean can hardly be correct as
the quadrangular symmetry is unlike that of the corresponding
part of any crinoid. Miller states that some collectors have con-
sidered the fossil to be the operculum of a coral, but he himself
does not seem to regard this interpretation of it as the correct one.
The genus Gontophyllum is the only coral possessing an operculum
of four triangular plates, but Cryptodiscus, from the configuration
of the disk, need not be compared with the operculum of Gonzo-
phyllum.

After a careful consideration I am led to believe that these
peculiar fossils may be the remains of meduse. Though the mod-
ern jellyfish are often of large size, they are singularly unfitted
for preservation as fossils because of the entire absence of hard
parts. Under favorable conditions, however, impressions of
these organisms have been preserved which admit of syste-
matic determination. Such impressions have been described
from the Upper Jurassic and the Upper Cretaceous in Europe.
Of a more questionable nature are the Cambrian fossils from
Sweden and America which have been referred to the Meduse
by Nathorst and Walcott.

Although Cryptodiscus has in general the symmetry of the
medusz, the idea of its being the mere impression of such a

FOSSIE MEDUSAS IN THE NIAGARA LIMESTONE 747

creature is abandoned for two reasons: First, the specimens
are not mere impressions in the rock, but are cavities with an
upper and a lower side, from which the actual solid substance of
some fossil has been dissolved. In the second place there is no
reason why the mere impression in the mud of the umbrella of
medusez, should generally break into regular quadrants and be
preserved as such. If we consider, however, that the specimens
of Cryptodiscus are the casts of the gastric cavities of meduse.
both of these difficulties are eliminated. The gastric cavities of
some living meduse are divided by thin partitions into four
pouches.’ If such a gastric cavity were filled with a fine sediment,
and if after the decomposition of the soft parts of the creature,
this cast should become fossilized, it is easy to imagine that the
four lobes of the cast might often become partially or wholly sepa-
rated or destroyed during the process. The one serious objec-
tion to this theory is that probably the material originally filling
the cavity of the medusa would be so nearly identical with that
in which the cast was buried, that it would not be leached out,
as would the shell of a brachiopod, for instance, which was of a
different character from the matrix in which it was buried.

DESCRIPTION OF SPECIES.

In reading these descriptions and examining the illustrations,
it should be kept in mind that they have all been drawn from
the impressions in the limestone and are consequently the
reverse of what the actual fossil would be. That is, what is
described as a groove in these impressions would be a ridge in
the actual fossil.

Cryptodiscus corrugatus n. sp. Figs. 1-2.

Disk 7 to 10™ in diameter, finely and deeply lobed on
the periphery. Funnel-shaped depression in the center 10 to
15™™ in diameter on the plane of the disk, narrowing below to
the base of the central stemlike process which is from 3 to 5™™
across and rises 6 to 8™™ to the general plane of the disk. Sur-

™See figure of a Calycozoon (Lucernaria), CLAUS and SEDGWICK, Text-Book of
Zoology, Vol. I, p. 257, Fig. 197.

748 STUART WELLER

face of the disk ornamented with from 18 to 20 radiating cor-
rugations on each quadrant, which extend about two-thirds of the
distance from the periphery to the center. Each groove upon the
corrugated surface extends to the tip of one of the narrow lobes
of the periphery. Central portion of the disk within the prox-
imal ends of the corrugations, with the exception of the central
depression, plane. The whole surface of the disk, in well-pre-
served specimens, minutely pitted. The four ridges which
divide the disk into lobes start from four angles upon the cen-
tral stemlike process. These ridges upon the more weathered
specimens become nearly or quite obsolete distally. The lobed
periphery of the disk is rarely perfectly preserved, and in only
the best-preserved specimens can the minutely pitted surface be
observed.

The specimens figured are from the collection of Mr. L. H.
Hyde; beside these the species is represented in the collections
of Walker Museum and of the Chicago Academy of Science. It
is the commonest species of the genus which has been observed,
and to it may probably be referred the specimen figured by
Miller from St. Paul, Ind.

Cryptodiscus hydet n. sp. Figs. 3-4.

Disk 5 to 8° in diameter, deeply lobed between the quadrants
giving the entire specimens much the form a of Maltese cross.
Distal margins of the lobes in no case perfectly preserved. Fun-
nel-shaped depression in the center 10 to 12™" in diameter on
the plane of the disk, narrowing to the base of the central] stem-
like process which is 5 to 6™™ in diameter, rounded over the top,
and rising from 5 to 7™™, a little above the general plane of the
disk. Surface of the disk smooth, sometimes with shallow, ill-
defined radial depressions extending from the center along the
lateral margins of each lobe to the distal angles. In one speci--
men a shallow, ill-defined radiating depression is seen extending
from near the center of the distal margin towards the proximal
angle. The four ridges which divide the disk into quadrants, start
from four angles upon the central stemlike process and are
prominent to the bottoms of the lobes of the periphery.

FOSSIL MEDUS4 IN THE NIAGARA LIMESTONE 749

The specimens figured are from the collection of Mr. L. H.
Hyde.

Cryptodiscus digitatus n. sp. Figs. 6-7. 5?

Only the detached quadrants of this species have been observed.
Each quadrant is deeply divided into three primary lobes, the
two lateral lobes being again divided in a manner not clearly
shown in the specimens. Surface covered with fine pits which
are coarser towards the proximal angles. Central depression
narrow and deep.

In one specimen, Fig. 5, which may belong to a distinct
species, the central lobe of the quadrant is deeply bifurcate, and
the lateral lobes are more deeply and more divergently divided
than in the type. This specimen is also of interest in showing
two quadrants somewhat separated, but still holding their rela-
tive position.

The specimens figured are from the collection of Mr. L. H.
Hyde.

Cryptodiscus bilobus n. sp. Fig. 8.

A single quadrant of this species has been observed, but that
one is nearly perfect. The distal margin is divergently bilobed,
with each lobe marked by a well defined, rounded, radiating
furrow which extends nearly to the proximal angle, dividing the
plane of the quadrant into three subequal triangular areas.
Each of these areas is ornamented with fine stria which diverge
from the margins of the two radiating furrows. The central
depression of the disk narrow and deep.

The type specimen is in the collection of Walker Museum.

EXPEANATION OF PEATE.

FIGS. 1-2. Cryptodiscus corrugatus.
1. A complete specimen with the periphery imperfect.
2. A single quadrant showing some of the narrow lobes of the
periphery.
Fics. 3-4. Cryptodiscus hydri.
3. A complete specimen with the periphery imperfect.
4. A single detached quadrant.

STUART WELLER

J 52

FOSSIL MEDUS4 IN THE NIAGARA LIMESTONE 751

Fics. 5-7. Cryptodiscus digitatus.
5. Two quadrants detached but still holding their relative position.
Possibly a distinct species.
6. The lower side of the type specimen.
7. The upper side of the type specimen.
Fig. 8. Cryptodiscus bilobus.
The type specimen.

STUART WELLER.
WALKER MUSEUM,
University of Chicago.

JE INT OIRILAUL,

Tue seventh session of the International Congress of Geolo-
gists was, and undoubtedly will always remain, the most remark-
able in the history of this organization. In conception and in
execution its plans far exceeded those of any session that pre-
ceded it, and were much greater than may be expected for any
that may follow. Governmental, industrial and social forces”
conspired to secure the success of the programme prepared by
the Russian geologists. A most powerful government not only
lent its hearty sympathy but furnished material assistance and
codperation. The Emperor and Empress received a delegation
from all the countries represented at the congress, and all mem-
bers in attendance were given a luncheon in the summer palace.
The Grand Duke Constantine Constantinovitch and the Princess
d’Oldenbourg and the Minister of Agriculture and Domains
opened the session and welcomed the members to St. Petersbourg.
The Grand Duke Constantine and the Grand Duchess Elisabeth
Mavrikievna entertained a large number of the geologists at their
palace. The mayor of St. Petersbourg invited all the members
to a reception in the city hall. These tokens of good will and
approval could not have been stronger; their genuineness was
proved by the material benefits enjoyed by all who took part in
the congress and the excursions. First-class passes were furn-
ished over all the railroads of European Russia and Finland,
good for three months, and entitling one to the use of sleeping
cars. Many official courtesies were also extended which often
amounted to complete freedom from customs and police surveil-
lance, and greatly simplified traveling through various govern-
mental provinces into remote parts of the empire. Industrial
enterprises, in any way indebted to geological science, exhibited

752

EDITORIAL 753

the same energy in advancing the interests of the visiting geo-
logists that characterizes their development of the natural
resources of the country making it possible to inspect mines
and study artificial exposures of great interest. The magnitude
of their hospitality also will long be remembered. It was
prompted by a generosity that seemed common to all classes of
people throughout the empire, as was shown upon one occasion
by the presentation of bread and salt by the miners of Colou-
bovka in token of the humble hospitality they would be glad to
show us in their houses if we could have visited them. The
same hearty welcome was met with in the cities and on the
farms of Finland, among the miners in the Urals, and in the
town, or camp, or monastery in Transcaucasia — everywhere the
same generous spirit and the same expressions of good will.
*

Tue brilliant success of the seventh session reflects great
credit on Russian geologists. To them are due both the con-
ception and execution of the programme. The labor required
for the preparation of maps and guides and for the arrangement
for the meeting and the excursions can hardly be realized by
anyone who has not been engaged in similar undertakings. The
general secretary, Professor Tschernyschew, devoted two years
to the preliminary work, and others, no doubt, had a very con-
siderable share init. The management of the excursions was
admirable, when it is remembered what difficulties of transporta-
tion and limitations of accommodation had to be overcome and
when the number of participants is taken into account. The
gratitude of all the excursionists is due to the leaders of the
several expeditions for the manner in which everything within
their control was conducted. Their labors and good intentions
were fully appreciated, except by those unfortunates whose first
impulse on all such occasions is to criticise and complain, and
whose subsequent effort is to find excuse for having done so.
When it is remembered that in addition to their responsibility
for the details of the excursion, the leaders have also to expound
the geology and undergo a cross fire of questions and scientific

754 EDITORIAL

criticism, and not infrequently to have judgment hurriedly passed
against them on insufficient evidence, the degree of indebtedness
to those who undertake such responsibilities is even greater than
at first appears.

*

THE actual meetings of the congress were reduced to a mini-
mum. Of the eight days set apart for the session in St. Peters-
bourg, four only were occupied by the reading of papers and by
discussion; two were given to the opening and closing cere-
monies, and two were taken for excursions. The wisdom of this
allotment is open to criticism. But it was evident at the time
that the most interesting feature of the session for the general
member was the social intercourse between members, proving
that the individuality of those present was of more immediate
interest than the papers read. The audience room unfortunately
was not well adapted to the purpose, owing to its large size and
the interruptions by members passing through it. It was appar-
ent to many that there would be a distinct gain if in future ses-
sions there should be meetings by sections for those interested
in specialized branches of geology, in connection with general
meetings, in which all might be interested. It would permit the
specialist to present more technical papers, and would allow of
more time for their discussion without encroaching upon the
time of others. Topics so diverse as paleontology and petrol-
ogy could be treated at the same time without conflict, and with
mutual advantage. The consciousness that a paper would be
too technical for a general audience, and that it should be made
as short as possible often deters one from devoting the necessary
time to its preparation. But with the possibilities of an audi-
ence such as might be commanded at an international congress,
and with time enough at one’s disposal, there could be no stronger
incentive for the presentation of one’s best possible production.
It is to be hoped that the French geologists will inaugurate this
practice at the session in Paris in 1900.

The nature of the scientific proceedings of the session will
be noted in another issue of the JOURNAL. jnce ale

EDITORIAL 755

Ir 1s pleasant to announce that our colleague of the JOURNAL
staff, Dr. Hans Reusch, has been engaged to give two courses
of lectures at Harvard University during the current year. In
the first half of the year he will treat of vulcanism, volcanoes,
eruptive rocks, earthquakes and other movements of the Earth’s
crust. In the second half he will describe the geology of
northern Europe and its relations to general geology. He will
give a weekly seminar to advanced students and will take part
in their field and laboratory work, his special subjects being the
geology of the seashore and the geology of special districts in
Europe. These lectures are given on the Sturgess- Hooper
foundation recently occupied by Professor J. D. Whitney, but
vacant since his death. (es

REVIEWS.

The Unpublished Papers of the Geological Survey of Brazil. (Fra-
balhos restantes ineditos da Commissio Geologica do Brazil.)
Boletim do Musen Paraense, Vol. II, No. 2. Oct. 1897,
pp. 155-204.

At the suggestion of Professor O. A. Derby, now chief of the State
Geological Survey of Sao Paulo, the Para Natural History Museum
(Museu Paraense) has undertaken to publish the unpublished papers
of the defunct Geological Survey of Brazil relating to the geology and
physical geography of the lower Amazon. The October number of the
Boletim contains the first installment of these papers. The parts thus
published consist of an “Introduction,” “The Breves Region,” and
“The Rio Tocantins” by Ch. Fred. Hartt, and of “The Island of
Marajo” and a “ Reconnaissance of the Rio Maecurti” by O. A. Derby.
These are to be followed later by other chapters on “‘ Rio Trombetas”
by Derby, on “ Paracary” by Herbert H. Smith, and on the “Tajury,”
“Paranaquara,” “Serra da Maxira,” and “Monte Alegre and Ereré”
by Hartt.

These papers represent work done by the extinct Commissao Geo-
logia do Brazil from 1875 to 1878, and it might be supposed that it is
now too late to publish them, especially as the Museu Paraense has
lately begun active work in the same region. But it should be remem-
bered that the State of Para, occupying the whole of the Lower Ama-
zon, covers an area of 443,900 square miles—nearly twice that of the
state of Texas—and that the difficulties of exploration in the dense
and trackless forests that cover that sparsely inhabited region are
almost or quite beyond the comprehension of those who have not
encountered them.

As Hartt well says, when he entered the Amazon valley for the first
time in 1870, it was, geologically, a ¢erra incognita. Since that time
and as the result of the tireless efforts of Hartt and Derby a vast
amount of important information has been gathered and published

756

REVIEWS Aa

upon the geology of the Amazon valley. Among these contributions
are Hartt’s and Rathbun’s papers on the Devonian fossils of Para,
Derby’s papers on the Carboniferous and on the Physical Geography
of the Lower Amazon, and Clarke’s report on the Ereré tribolites,
besides a number of papers of minor importance, but all of them of
value.

Director Goeldi deserves great credit for bringing out at last the
work of the men who have done so much and such important pioneer
work for geology in Brazil.

The Devonian fauna of the Red Maecurt. By Dr. F. Karzer.

The same number of the 4o/etim contains an interesting paper by
Dr. Friederich Katzer on “The Devonian fauna of the Rio Maecurt,
and its relations to the faunas of the other Devonian terranes of the
globe.” His studies are based upon the materials gathered by Hartt
and Derby and some later collections made in 1896. The conclusion
is reached that the Rio Maecurti fauna resembles more closely that of
the middle Devonian of North America than it does the lower Devon-
ian with which it has hitherto been correlated. One of the beds he
correlates more exactly with the Hamilton of the New York section.
In comparing the fauna with the Devonian of Europe he says it should
be compared to the upper part of the lower Devonian. ‘‘ But as there
can be no doubt that the Rio Maecurt' fauna corresponds to that of
the Hamilton of North America, which is now considered to belong to
the middle Devonian we are obliged to assume a@ non-stmultaneous
development of certain forms in the American and European provinces of
the Devonian sea, or a migration of these forms from the latter to the
former provinces. Thus the spirifers with long wings show their prin-
cipal development in the Rhenish Lower Devonian, but in North
America and on the Rio Maecurti only in the middle Devonian. /yvo-
pidoleptus carinatus Conrad is found on the Rhine in the lower Coblenz
beds, while in America, including the Rio Maecurt territory, it occurs
only in the middle Devonian. ‘The same is true of corals of the genus
Pleurodictyum which, in Europe, are found predominating in the lower
Devonian and in America in the middle Devonian.

“All this shows that these groups of animals, probably on account
of progressive alterations, especially of depth, in the sea of the first

758 REVIEWS

Devonian epoch, migrated from Central Europe to America where
they are now presented in the middle Devonian.”

Dr. Katzer’s study of these Brazilian fossils is especially interesting
in connection with the work of Dr. Henry S. Williams on the fauna of
the Cuboides Zone. (Bull. G. S. A. I. 481-500.)

Joun C. BRANNER.

Report of the United States Deep Waterways Commission. By the
Commissioners JAMES B. ANGELL, JOHN F. RussELL, LYMAN
E. CooLey. Washington, 1897.

The Deep Waterways Commission was appointed by the President
in response to a joint resolution of Congress, introduced in February
1895, to make inquiry and report after conference with such similar
Commissioners as might be appointed on behalf of Great Britain or
the Dominion of Canada, concerning the feasibility of the construction
of canals which will enable vessels engaged in ocean commerce to pass
into the Great Lakes. The United States Commissioners and also
those appointed by the Canadian government have devoted a year or
more to the investigation and have prosecuted their inquiries with such
thoroughness that their report contains much of value to geologists
and hydrographers as well as the commercial world. It embraces 263
pages of descriptive and statistical matter and an elaborate series of
maps, diagrams and profile sections.

Of interest to geologists and hydrographers are the tables and dia-
grams exhibiting the fluctuations in the levels of the Great Lakes and
their outlets for each month from 1860 to 1895; a report and dia-
grams setting forth the effects of gales on Lake Erie ; and an accurate
map of the basin of the Great Lakes. The length of the ice season is
treated with great fullness, there being 176 specific tables and five dia-
grams, covering not only the basin of the Great Lakes but much sur-
rounding territory. The profiles setting forth the variations in depth
of the several lakes with their connecting channels and of the St. Law-
rence and Hudson rivers, give a clearer impression than can be obtained
from charts. The great inequalities in depth found in the lower por-
tions of the Hudson and St. Lawrence rivers are brought out with
especial clearness, and they will stimulate inquiry into the history or
mode of development of such abnormal stream beds.

REVIEWS 759

The leading deductions from the work of the commission are as
follows: First, that it is entirely feasible to construct canals between
the several Great Lakes and the seaboard which will be adequate to
any scale of navigation that may be desired; second, the most eligible
route from the heads of Lakes Michigan and Superior is through the
several Great Lakes and their intermediate channels, together with a
proposed ship canal from Tonewanda to Olcott in Lake Ontario, from
which the Canadian seaboard may be reached by way of the St. Law-
rence River, and the American seaboard may be reached by way of the
St. Lawrence River, Lake Champlain, and the Hudson River, or by
way of the Oswego-Oneida-Mohawk Valley, and the Hudson River.
The direct line through Georgian Bay, Lake Nipissing, Mattawa, and
Ottawa rivers, although presenting no great engineering difficulties, is
not considered an available alternative to the route by way of Lake
Erie, since the work of construction 'is much more serious, the water
supply limited, the ice season longer, and the amount of traffic along
the line much smaller. Until comprehensive surveys have been made
it will be impossible to say how far lockage and restricted channels will
offset the apparent saving in distance. Boyle

The Former Extension of the Appalachians across Mississippi, Loutsi-
ana and Texas. By PRoFEssoR J.C. BRANNER. From the
American Journal of Science, Vol. 1V, November 1897.

The paper is a brief and compact statement of the ground upon
which the author concludes that the Appalachian Mountains formerly
had the extension indicated by the title. That the mountains disap-
peared by subsidence over the area named is evidenced by the following:
(1) the reversal of the drainage of both the Arkansas and the Texas
Carboniferous areas; (2) the truncation of the eastern part of the
Ouachita uplift by Cretaceous and Tertiary sediments; (3) the general
slope of the Ouachita uplift is toward the east; (4) the general direction
of the drainage of the Ouachita uplift is toward the southeast, which is
the direction of the principal axis of disturbance; (5) the faults and
folds across the eastern end of the Boston Mountains are approximately
parallel to the Cretaceous and Tertiary margin; (6) the great fault
near the Tertiary border of Texas and the still greater faults in Ala-
bama, with the downthrow (which is great) on the embayment side of

760 REVIEWS

the Appalachian axis; (7) the eruptive rocks and hot springs accom-
panying the faults and Tertiary border in Texas and Arkansas; (8) the
great thickness (5000 to 10,000 feet) of the Cretaceous and post-Creta-
ceous sediments in the depressed area.

Among other important things, the author concludes that the
Ouachita uplift is the structural equivalent of the Cincinnati-Nashville
arch; that the Coal Measure drainage of the Illinois-Indiana-Kentucky
area was into the Carboniferous mediterranean sea through the Arkansas
valley; and that the drainage of the Arkansas and Texas Carbonifer-
ous areas was reversed about the close of Jurassic times, when the
orographic movements to the east submerged the Appalachians in
Mississipi, Louisiana and Texas.

The Palzeozoic sediments on the south side of the Ouachita uplift
are coarser than on the north side, indicating that they came from the
the south. The same change of sediments is seen in the Silurian
novaculites of the Ouachita uplift. It is on this ground that the
Ouachita uplift is made the equivalent of the Cincinnati arch.

A. H. PURDUE.

ARKANSAS STATE UNIVERSITY.

Maryland Geological Survey, Vol. 1. Wm. BuLLock Criark, State
Geologist. The Johns Hopkins Press, Baltimore, Md.

Following the good example set by some of the recent state
geological surveys, the survey of Maryland presents in its first published
volume a summary of the geological work which has already been
done within the state. This ground is covered in Parts II, III and IV
of the present volume, each of which treats of the subject from a dif-
ferent point of view. ‘The first gives a history of the various organi-
zations which have carried on geological work within the state, and
references to the work of individuals not immediately connected with
organizations. The next presents a summary of existing knowledge
concerning the geology of the state, unencumbered by references to
the men who did the work, the dates at which their results became
known, and the publications where they were set forth, references
which, if present, would seriously interrupt the continuity of the
sketch. In this sketch are incorporated some of the results of the
reconnaissance work of Dr. Clark and his assistants since the organiza-

MA CIINT PUBLICA TIONS. 761

tion of the present survey. The third part of the report referred to
above (by Dr. E. B. Mathews), is a careful bibliography of the publica-
tions, both textual and cartographic, touching the geology and natural
resources of the state. These chapters, which constitute the strictly
geological part of the volume, are prefaced by a chapter which sets
forth the plans and purposes of the survey — a chapter well worth the
perusal of those who are charged with the organization or execution of
such surveys.

Part V is areport by Dr. L. A. Bauer on the magnetic work in
Maryland, and includes a sketch of the history and objects of magnetic
surveys. Dr. Bauer has determined the magnetic elements at a num-
ber of points, and has brought together all data which are now known
concerning this interesting subject, so far as applied to the state.

The volume is illustrated by seventeen well-executed plates and
maps, among which are a geological map of the state as now under-
stood, an isogonic map, and a map showing lines of equal magnetic
inclination .and the preliminary lines of equal magnetic force (for
January 1897).

The volume is to be commended not only for its contents, but for
the excellence of its typographic work. In this respect it is in pleasant
contrast with the cheap volumes sometimes issued by similar organi-
zations. Regs S.

RECENT PUBLICATIONS.

—ANDRE#, PROFESSOR DR. Die Foraminiferen-Fauna im Septarienthon
von Frankfurt a. M. und ihre vertikale Verteilung. Frankfurt a. M.
Germany, 1894.

Annales de la Société Geologique de Belgique. May 1897, Liege, Bel-

gium.

—Annual Report, Department of Minesand Agriculture, New South Wales,
for the year 1896. Sidney, Australia, 1897.

—ASHE, WILLIAM WILLARD, Assistant in Forestry, North Carolina Geo-
logical Survey. The Possibilities of a Maple Sugar Industry in
western North Carolina. Winston, N. C., 1897.

—BAIN, H. F. Geology of Polk County.—lowa Geological Survey, Vol.
VII. Des Moines, Ia., 1897.

—BAKER, FRANK COLLINS. Onthe Modification of the Apex in Gastropod,
Mollusks. Reprinted from the Annals of the New York Academy of
Sciences, IX. 1897.

762 RECENT PUBLICATIONS

—BaARsour, ERwIN H. Additional Notes on the New Fossil Daimonelix.
Its Mode of Occurrence, its Gross and Minute Structure.—University
of Nebraska, Lincoln, 1894. Nebraska State Board of Agriculture,
1896, Report of the Geologist.

—Baur, G. New Observations on the Origin of the Galapagos Islands.
With Remarks on the Geological Age of the Pacific Ocean.—Nos. I
and II. Reprinted from American Naturalist, October 1897.

—BayLey, W.S. and W. H. Hogpss. A Summary of Progress in Miner-
alogy and Petrography in 1894. (From Monthly Notes in the Amer-
ican Naturalist.) Waterville, Me., 1895.

—BECKER, GEORGE F. On Certain Astronomical Conditions Favorable
to Glaciation.—American Journal of Science, Vol. XLVIII, 1894.
—BERTOLOLY, DR. ERNST. Ripplemarken. Inaugural-Dissertation.

Frankenthal, Germany, 1894.

—BLATCHLEY, W. S., State Geologist. Twenty-first Annual Report, 1896,
Department of Geology and Natural Resources. Indianapolis, 1897.
Bulletin de la Société Geologique de France, July 1897. Paris.
Bureau of American Ethnology. W J McGee, Director Fifteenth
Annual Report (1893-4).

—BRANNER, J.C. The Former Extension of the Appalachians Across
Mississippi, Louisiana, and Texas.—American Journal of Science,
Vol. IV, November 1897.

—Buffalo Society of Natural Sciences, Bulletin, Vol. V, No. 4, 1894.

—CALL, M. ELiswortu, La Cartographie de Mammoth Cave (Kentucky).
Extrait du Bulletin de la Société De Spéléologie. Janvier-Mars et
Avril-Juin, 1897.

—CALLAWAY, CHARLES. On the origin of some of the gneisses of Ang-
lesey.—Quarterly Jour. of Geological Society for August 1897. Vol.
LIII. London.

—Club Alpin Frangais.

Bulletin Mensuel. Nos. 6 et 7, 1897.
Annuaire du Club Alpin Frangais, 1896. Paris, 1897.

—CORSTORPHINE, GEORGE S., Geologist. First Annual Report of the
Geological Commission of the Cape of Good Hope, 1896.

Cape Town, Africa, 1897.

—DAVIDSON, GEORGE. The submerged valleys of the coast of California,
U.S.A., and of Lower California, Mexico.—California Academy of
Sciences, San Francisco, June 26, 1897.

—Davis, WILLIAM Morris. The Harvard geographical models with a
note on the construction of the models. (4 plates.) Proc. Bost. Soc.
of Nat. Hist., Vol. XXVIII, No. 4, pp. 85-110.

—DAWSON, GEORGE M. Some observations tending to show the occur-
rence of secular climatic changes in British Columbia.—Trans. Royal

RECENT PUBLICATIONS 763

Society of Canada, Vol. II, Section V, Second Series, 1896, Ottawa,
1897.
The Physical Geography and Geology of Canada. Toronto, 1897.

—Dawsov, G. M., Presidential Address, Geological Section British Assn.
for the Advancement of Science. The Pre-Cambrian Rocks of Canada.
Toronto, August 1897.

—DopGE, RICHARD E. School Geography in the United States.
Reprinted from the Scottish Geographical Magazine for October 1897.

—FAIRBANKS, HAROLD W. Review of our knowledge of the geology of
the California coast ranges.— Bulletin Geol. Soc. of America, Vol. VI,
pp. 71-102.

An analcite diabase from San Luis Obispo County, California. University
of California, Berkeley, 1895.

—FAIRCHILDS, HERMAN LEROY. Proceedings of the Sixth Summer
Meeting Geol. Society of America, at Brooklyn, N. Y., Aug.14 and 15,
1894.

The Geological History of Rochester, N. Y.—Proc. of the Rochester
Academy of Science, Vol. II.

The evolution of the ungulate mammals.—Ibid.

The length of geologic time.—Ibid, Vol. IX.

—Geological Institution of University of Upsala, Bulletin, edited by H.
SJORGREN. Upsala, 1896.

—Geological Survey of Alabama.

Report on the Valley Regions of Alabama _ Part II. The Coosa
Valley Region. By Henry McCalley, Asst. State Geologist. Mont-
gomery, 1897.

—Geological Magazine, Vol. IV, No. 7, London, July 1897.

—GRESLEY, W.S. The “slate binders” of the “Pittsburg” coal bed.
From American Geologist, Vol. XIV, December 1894.

—GRIMSLEY, G. P. The Crinoids of Cecil County in Northeastern
Maryland.—Journal of Cincinnati Society of Natural History, April
and July 1894. ,

—HALL, C. W. and F. W. SarpEson. The magnesian series of the north-
western states.—Bull. Geol. Soc. of America, Vol. VI, pp. 167-108,
Rochester, Jan. 1897.

Diceratherium Proavitum.—Am. Geol., Vol. XX, November 1897.

—HATCHER, J.B. The Cape Fairweather Beds; a new Marine Tertiary
Horizon in Southern Patagonia. Princeton University, August 2, 1897.
On the geology of Southern Patagonia.—Amer. Jour. Sci., Vol. IV,
November 1897.

Iowa Geological Survey: Vol. VI. Report on Lead, Zinc, Artesian
Wells, etc., by S. Calvin, State Geologist, A. G. Leonard and H. F.
Bain, Asst. State Geologists.

704 LIE CSBIN TIE JAQISL INCA IOV OUN GS,

—Hopkins, T.C. and C. E. SIEBENTHAL. The Bedford Oolitic Limestone
of Indiana. From the Twenty-first Annual Report of the Department
of Geology and Natural Resources. 4 maps. Indianapolis, 1896.

—Hovey, E.O. A study of the cherts of Missouri—American Journal of
Science, Vol. XLVIII, Nov. 1894.

—Instituto Geologico de México, Boletin, Nums. 7, 8 y 9. El Mineral de
Pachua. Mexico, 1897

—IlIowa Academy of Sciences, Proceedings, 1896. Vol. 1V. Des Moines,
1897.

—lowa Geological Survey, Annual Report, 1896, Vol. VII, Des Moines,
1897.

—KnowLTON, F. H. A new fossil Hepatic from the Lower Yellowstone
in Montana (plate 219).—Bulletin of the Torrey Botanical Club, Vol.
21, No. 10, 1894.

—Lawson, A.C. The geomorphogeny of the coast of Northern Cali-
fornia. University of California, Berkeley, 1894.

—LyMAN, BENJAMIN SMITH. Some Coal Measures sections near Peytona,
West Virginia (with 2 large maps). Reprinted from Proc. American
Philos. Society, Vol. XX XIII, Nov. 23, 1894. Philadelphia.

—MarsH, O.C. Principal Characteristics of the Protoceratide. Am.
Jour. of Sci., Vol. IV, 6 plates. September 1897. On the Pithecan-
thropus Erectus Dubois from Java (1 plate). Amer. Jour. Sci., Vol.
XEEXG Pebanhso se

The Reptilia of the Baptanodon Beds. /dzd., Vol. L, November 1896.
Note on Globular Lightning, /ézd., Vol. I, January 1897.

The Age of the Wealden. Jézd., Vol. 1, March 1896.

The Affinites of Hesperines, /ézd@., Vol. III, April 1897.

—Maryland Geological Survey, Vol. I. Johns Hopkins Press, Baltimore,
Md., 1897.

—MERRIAM, J. C. Ueber die Pythonomophen der Kansas-Kreid. Stutt-
gart, 1894.

—MILLER, GERRIT S., Jk. North American fauna No. 13. Review of
the North American beds of the family Vespertilionide. U.S. Dept.
of Agriculture, Washington, D. C., 1897.

—Mining Bulletin. Vol. III, No. 3, May 1897. State College, Pa.

—MUSCHKETOW, J. Allegemeine geologische Karte von Russland, Blatt
114. Geologische Untersuchungen in der Kirgisen-Steppe in Jahre
1894. St. Petersburg, 1896. k

—North Carolina Geological Survey: First Biennial Report of the State
Geologist, 1891-2, J. A. Holmes.—Bulletin No. 1, Iron Ores of North
Carolina. A preliminary report by Henry B. C. Nitze, Assistant Geol-
ogist.—Bulletin No. 3, Gold Deposits of North Carolina, by Henry B.
C. Nitze and George B. Hanna.—Bulletin No. 5, The Forests, Forest

KRECENE PUBLICATIONS i 765

Lands and Forest Products of Eastern North Carolina, by W. W.
Ashe, in charge of investigation.—Bulletin No. 9, Monazite and Mona-
zite Deposits in North Carolina, by Henry B. C. Nitze, Assistant
Geologist.— Bulletin No. 11, Corundum and the Basic Magnesian
Rocks of Western North Carolina, by Joseph Volney Lewis.

—NORTON, WILLIAM HARMON. Artesian Wells of Iowa. Iowa Geol.
Survey, Des Moines, 1897.

—ORrRTMANN, A. E. Oysters of Patagonia.—(Plate XI,) Am. Jour. Sci.,
Vol. IV, 1895.

—PENCK, L. A., ED. BRUCKNER, and Dr. LEON DU PASQUIER. Le Sys-
téme Glaciare des Alpes. Neuchatel, 1894.

—PIPEROFF, DR. CHARLES. Geologie des Calanda.—Beitrage zur Geol-
ogishen Karte der Schweiz. Bern, 1897.

—PRESTWICH, JOSEPH. A possible cause of the origin of the tradition of
the flood.—Author’s copy, copyright. London.

—PROSSER, CHARLES S. Kansas River section of the Permo-Carboniferous
and Permian rocks of Kansas.—Bull. Geol. Soc. of America, Vol. VI,
pp. 29-54. Rochester, 1894.

—Rasot, M. CHARLES. Les Variations de Longuer des Glaciers dans les
Régions Arctiques et Boréalis. Genevé, 1897.

—RANSOME, LESLIE F. The geology of Angle Island.—University of
California. Berkeley, 1894.

—READE, T. M. Present Aspects of Glacial Geology. Extracted from
Geological Magazine, December 1896.

The Glacio-Marine Drift of the Vale of Clwyd. From the Quarterly
Journal of the Geological Society for August 1897, Vol. LIII. London,
1897.

—READE, T. MELLARD. The Dublin and Wicklow-Shelley drift.—Proc.
of the Liverpool Geological Society, 1893-4. Liverpool, 1894.

—Revisita de Obras Publicas E Minas. Nos. 329 E. 330. Lisbon, 1897.

~-ROLFE, C. W. List of altitudes in the state of Illinois.—Article IV,
Vol. IV, Bulletin of the State Laboratory of Natural History, Cham-
paign, Ill. Springfield, 1894.
—SARDESON, F. W. On Streptelasma Profundum (Owen) S. Cornicu-
lum, Hall.—Am. Geol., Vol. XX, Minneapolis, November 1897.
—SCUDDER, PROFESSOR S. H. The fossil insects of North America.
Vols. land II. With special reference to Canadian specimens, by
H. M. Ami, M. A.—Reprinted from the Canadian Record of Science,
October 1893. ;

--SEARS, JOHN H. Report on the Geology of Essex County, Mass., to
accompany map.—Bulletin of Essex Institute, Vol. XXVI, 1894.
Salem, Mass. Geological and Mineralogical Notes, Nos, 7 and 8.
Ibid, Vol. XXVI, 1894. Salem, 1895.

766 TE CENA OBIE CA ALOIS

—SHALER, N.S. Evidences as to change of sea level.—Bull. Geol. Soc.
Am., Vol. VI. pp. 141-166. Rochester, 1895.

SmiTH, E. A. Sketch of the life of Michael Tuomey.—Am. Geologist,
Vol. XX, October 1897. Sketch of the mineral resources of Alabama.
—Published by direction of the Commissioner of Agriculture.

—SmitH, J. P. The development of Glyphioceras and the Philogeny of
the,Glyphioceratide. (3 plates.) Proc. California Academy of Sci-
ences. San Francisco, October 16, 1897.

—SmytTH, B. B. The age of Kansas.—Trans. Kansas Acad. Sci., Vol. IX,
1883-4. Topeka, Kan.

—SPENCER, J. W. The Yumuri Valley of Cuba.—Geol. Mag., November
1894, London, Eng.

— Transactions of the American Institute of Mining Engineers, Vol. XXVI.
Index Vols. XXI to XXV.

-— Transactions of the Edinburgh Geological Society, Vol. VII, Part I.
Edinburgh, 1894.

—U. S. Geological Survey: Seventeenth Annual Report of the United
States Geol. Survey, Part I, Director's Report and other papers; Part
II, Economic Geology and Hydrography ; Part III, Mineral Resources.
Water supply and irrigation papers, No. 4—A reconnaissance in
Southeastern Washington, by I. C. Russell. Washington, 1897.

—WAHNSCHAFFE Dr. F. Mittheilung itber Ergebnisse seiner Aufnah-
men in der Gegend von Obornik in Posen. Berlin, 1897. Die Lager-
engsverhaltnisse des Tertiars und Quartars der Gegend von Buckow-
Berlin, 1893.

—WestTGaTE, Lewis G. The age of the crystalline limestones of Warren
County, New Jersey.—Am. Geologist, Vol. XIV, December 1896.
—WHITEAVES, J. F. Description of a New Genus and Species of Cys-
tideans from the Trenton Limestone at Ottawa. Reprinted from the

Canadian Record of Science, January 1897.

—WHITFIELD, R. P. On new forms of Algz from the Trenton limestone,
with observations on Buthograptus laxus Hall.—Bull. Am. Museum of
Natural History, Vol. VI, Article XVI, pp. 351-358. New York, 1894.

—WriGuT, A. A. The ventral armor of Dinichthys—Am. Geologist,
Vol. XIV. November 1804.

THE

JOURNAL OF GEOLOGY

NOVEMBER-DECEMBER, 18597

hit GEOUOGleReLATIONS OF THE MARTINEZ
GROUPOM CAEIBORNIA AT THE Twerrcak
LOCA LIA

THE term ‘“ Martinez Group” was first used by W. M. Gabb
in his classification of the Cretaceous of California, the group
of strata provisionally so designated being considered by him
as standing between the Chico of his Cretaceous A and his Tejon
or Cretaceous B. The Martinez was said to be of small geograph-
ical extent and to bear such a relation to the Chico that future
investigation might show it to be a part of that group. About
sixty species were listed by Gabb from the group, most of them
having been collected near the town of Martinez, in Contra Costa
county.

For a number of years after the publication of the second
volume of Gabb’s work on the paleontology of California, the
Martinez group was scarcely mentioned in geological literature,
probably because, as described by him, it was not well under-
stood. However as the Cretaceous B or Tejon came to be
generally considered as Eocene the importance of the group, as
a possible connecting link between the Chico-Cretaceous and
the Tejon-Eocene, became evident.

See Rep. Geol. Surv. of Cal. Paleontology, Vol. II, p. 13 of Preface. Gabb
divided his Californian Cretaceous into a lower division, A, including the Shasta,
Chico, and Martinez (?), and an upper division, B, or the Tejon. His Cretaceous B

is now generally regarded as Eocene.
VoL. V, No. 8. 767

768 JOHN C. MERRIAM

In a recent publication’ by Mr. T. W. Stanton the fauna and
stratigraphy of a number of the most important of Gabb’s Mar-
tinez localities have been clearly discussed and a complete reor-
ganization of the hitherto heterogeneous group effected. Mr.
Stanton has shown the Martinez of Gabb to consist of two parts,
one characteristic Cretaceous and inseparable from the Chico
group, the other being more closely related faunally and strati-
graphically to the Tejon-Eocene than to the Chico. The upper
portion was therefore placed with the Tejon and designated as
Lower Tejon. Asa possible modification of his classification
Mr. Stanton states that, ‘‘if more detailed field work makes it
desirable to retain the name (Martinez) at all, it should be
festricted to) the Hocene) (uppem)Eportion ja a

In the following discussion the name Martinez is applied to

””

that portion of Gabb’s Martinez group which remains, after the
removal of the Chico-Cretaceous element. The writer’s state-
ments are based on observations, extending over a period of
several years, made in the typical region for the group, viz., that
adjacent to the town of Martinez.

In the hills to the southwest of Martinez strata of unques-
tioned Chico age, containing a characteristic fauna, occur over a
considerable area. Ina fine outcrop of compact, bluish sand-
stone occurring on the west side of Alhambra Valley, and near
the top of the Chico, the writer found an abundance of fossils,
characteristic of this group, which are listed in the table below,
under Locality No. 1.. From this point to the east and west the
structure of the strata is anticlinal, showing an apparently con-
formable series up as far as the Miocene on each side.

From the standpoint of stratigraphy, one would hardly be
disposed to find fault with Gabb’s conception of the Martinez,

since in this, the typical locality, the Chico, Martinez, and Tejon,
appear everywhere to be conformable, while numerous com-
plications of the stratigraphy have still farther increased the dif-
ficulty of separating these three groups on stratigraphic grounds.

*The Faunal Relations of the Eocene and Upper Cretaceous on the Pacific Coast
17th Ann. Rep. U.S. Geol. Survey, 1895-6.

GEOLOGIC RELATIONS OF THE MARTINEZ GROUP 769

Lithologically there are some differences between the Mar-
tinez and the adjoining formations, the most important of which
are the slightly different aspect of its sandstones and the fre-
quent presence in them of considerable quantities of glauconite.
The sandstones are often grayish, differing from the yellowish
or bluish rocks of the Chico and the massive white to dull red
Tejon sandstones. In many places the Martinez contains large
quantities of glauconite disseminated evenly through the sand-
stones in rounded grains of considerable size. Glauconite does
not seem to occur at all in the Chico but may possibly be found
toward the base of the true Tejon. The truly glauconitic rocks
belong principally to the Martinez.

While the group shows little which would serve to separate
it stratigraphically or lithologically from the over and under-
lying formations, its fauna, on which Gabb based his classifica-
tion, contains numerous elements throwing light on its geologic
relations. Between the Chico-Cretaceous and the Miocene there
are two distinct faunas present, viz., the Martinez (in part) and
Tejon of Gabb, or the Lower and Upper Tejon of Mr. Stanton.
As other criteria failed to separate satisfactorily the Chico, Mar-
tinez, and Tejon, extensive fossil collections were made by the
writer at all possible points. A series of rich localities running
across the strike from the Chico to the Tejon furnished the
sequence of faunas as shown in the table on pages 770 and 771.

An examination of these lists shows that the lower Martinez
beds, as stated by Mr. Stanton, have a fauna distinct from that
of the Chico, and that, while the two sets of rocks may seem to
be conformable, an unconformity, as yet unobserved, probably
exists. “here are mo, Species “common to localities 1-and 2
excepting Dentalium Coopert which ranges up into the Tejon and
appears to be identical with a form occurring in the lowest Mio-
cene. Other localities furnishing a few imperfect fossils are
known in beds perhaps somewhat lower down than Locality No.
2 but as yet no distinct overlapping of the two faunas has been
discovered.

Locality No. 3, higher up in the group, furnishes a fauna of

To

TABLE SHOWING CHANGES OF FAUNA FROM CHICO TO TEJON."

JOHN C. MERRIAM

LocaLity No. 1.—TYPICAL
CHICO.

Corbula cultriformis Gabb....
Meekia sella Gabb..........-
Meekia navis Gabb
Meretrix arata or fragilis Gabb
Mytilus quadratus Gabb......
Mytilus pauperculus Gabb....
Nucula truncata Gabb
Pecten martinezensis Gabb...
Pectunculus Veatchi Gabb....
Tellina Hoffmanniana Gabb..
Tellina aequalis Gabb (?)....
Venus varians Gabb.........
Cinulia obliqgua Gabb
Cylindrites brevis Gabb (?)...
Dentalium Coopert Gabb
Gyrodes expansa Gabb.......
Perissolax brevirostris Gabb

ee eee ce weer

ol
OO CONT ANH WN

II

ean ln a |
NS OMDB WN

Pugnellus hamulus Gabb....
Solarium tnornatum Gabb...
Helicoceras vermicularis Gabb.
Sharks’ teeth 2 sp...........
Teleost fish scale ...........
Locaity No. 2.--LOWER
MARTINEZ.

Flabellum Remondianum Gabb
Placosmilia n. sp
Schizaster (?) n. sp
AFEANS SP. 0.00 ec eneses ee
Cardium Coopert Gabb......
Cucullea Mathewsoni Gabb.. .
Leda Gabor. Contes. see
Lucina sp
Meretrix sp
MW Cehie Ws SD50'500.005955 coc
Pholadomya nasuta Gabb.....
Tapes quadrata Gabb (aff)...
Tellina n. sp
14 Actacon (?)n. sp
15 Cylichna costata Gabb........
16 Dentalium Coopert Gabb
17 Discohelix n. sp....
18 Fusus n. sp. (a)
19 Fusus n. sp. (0)
20 Indet. nov :
21 Neptunea mucronata Gabb....
22 Perissolax Blakei Conr. n. var.

No ee
Ooo Co

tN
Noe

ON oOMBWN SS

No}

10
II
12
12 SUGDEN Fors 0000005000

sec e ee ee ee ee

Chico
| Martinez

| Tejon

| Chico

Tejon

HHH HH XE KK KKK KEK KK

+

*

NNN LY
AWN B Lo

tw

NON
Oo

CN OMB WN

Il
I2
13
14
15
16

17
18

Siphonalia lineata Stanton....
Turritella sp
Urosyca caudata Gabb......-.
Urosyca 1. Sp
Xenophora n. sp
Glauconite
Horamimifenarererreieeeriiierer
LocaLity No. 3.—UPPER
MARTINEZ.

Arca 0. S
Cardium Coopert Gabb
Cucullea Mathewsont Gabb..
Mii GBRGE (COR 5 5.05 6000 5006
Modiola ornata Gabb
Pholadomya nasuta Gabb.....
Solen n. sp
Tellina (?) unduiifera Gabb. .
Brachysphingus liratus Gabb.
Bullinula (2) n. sp..s.....--
Dentalium Coopert Gabb
JEESIS Mo Si506006 2000000006
Heteroterma Gabbi Stanton...
Perissolax Blakei Conr. n. var.
Stiphonala lineata Stanton....
Strepsidura pachecoensis, Stan-

we es 0 0 eee «© 0 © ee ©

see

Turritella infragranulata Gb.
Urosyca caudata Gabb.......

LocaLity No. 4.—NEAR UPPER

ON AnNBRWN 4

LIMIT OF MARTINEZ.
Nummuloid
Schezastera(e)emyiSpraie eet
Cardium Coopert Gabb
Cardita Hornti Gabb........
WIDQHTMO DE FV00600 600% 000006
SUG i Gso00000c000006006
Tellina Hornit Gabb
Tellina n. sp
THEIR (2) We GOs o6'o0 56 6000
Ampullina striata Gabb (cozf.)

Dentalium stramineum Gabb..|*

Ficopsis sp. (near Remonat)..
Megistostoma striata Gabb....
Morio sp. (tuberculatus?).....
SWOUTE Ws Sooosacedooso0c
Tritonium N. SP ...eeevevees
Tritonium (?) n. sp
Turris n. sp
UGA. 5. Fo (Bo no00 000%

eee wee

%* * * * * | Martinez

XX eK KK HFK KKK

%* %* *

HE a

*

*—t+

x * * *

= An asterisk indicates common or characteristic; a dagger, rare or characteristic

of some other horizon.

GEOLOGIC RELATIONS OF THE MARTINEZ GROUP 771

TABLE.— Continued.*

yy a

o\-El« ol-s|«

O|zlo Ole ho

al Slo a(S] 2

O|;a |e O\4|F

LocaLity No. 5.—TEJON, A 10 Amauropsis alveata Gabb.... *

SHORT DISTANCE ABOVE Lo- Il CylichnacostataGabb........ Eo!

CALITY NO. 4. 12 Conus Remondi Gabb........ *

1 Trochosmilia striata Gabb.... * 1113 Dentalium Coopert Gabb....|*|* | *

2 Cardium Brewert Gabb...... * 114 Ficopsis Remondi Gabb....... *

3 Cardium Coopert Gabb...... *| 7115 &2copsts sp. (near Remondz)... * | *

4 Cardita Hernit Gabb........ * 1/16 orto sp. (tuberculatus)...... Tales
5 Meretrix Hornit Gabb....... *\\17 Lertssolax Blaket Conr. Typ.

6 Meretrix uvasana Conr...... * VAT a ste erereasieter eis tereteeteio: eters *

7 Modiola ornata Gabb........ T|*||18 Remelia canalifera Gabb..... *

8 Nucula truncata Gabb....... */)*1%*|!19 Turritella uvasana Cont..... ca:

g Pectunculus sagittatus Gabb. . * 1120 Oliveratocalifornica Cooper .. *

the same type as that of No. 2 but containing some forms as
Tellina (?) undulifera, Turritella infragranulata, and Brachysphingus
firatus, not present in the lower beds. One minute specimen of
the characteristic Tejon form, Modiola ornata, was obtained at
this horizon.

At Locality No. 4, near the upper limit of the Martinez,
about one third of the fauna is composed of species known from
the Tejon. Of these forms Dentalium stramineum is a long-lived
species ranging from Chico to Tejon. Cardium Cooperi, though
known from Tejon beds, is not a common or characteristic fossil
of that group, while it ranges through the Martinez and is one
of its most characteristic species. The Cardita belongs to the
Tejon species described as Hornit by Gabb but may be a new
variety. MJegistostoma striata, Tellina Horn and the Morio seem
to be typical Tejon forms and are not found below the uppermost
beds of the Martinez. The Ficopsis sp. is a form known from the
Upper Martinez and Lower Tejon. Imperfect specimens of a
foraminifer related to Nummulites are abundant at this locality.
Though the fauna at this horizon is certainly closely related to
that of the true Tejon, only three good species are common or
characteristic forms in that group.

t An asterisk indicates common or characteristic; a dagger, rare or characteristic
of some other horizon.

772 JOHN C. MERRIAM

At Locality 5, a short distance (less than 100 feet) above No.
4, fossils of the well-marked fauna to which Gabb gave the name
Tejon are found in abundance, Cardium Coopert being the only
really characteristic Martinez species associated with them. No
localities showing more gradation between the Martinez and
Tejon faunas than those here discussed have so far been discov-
ered by the writer.

Numerous other collections made between Localities 2 and 3
and between 3 and 4 furnished gradations from one to the other,
with some additional species not mentioned in the foregoing
lists.

In the following table there are placed together all of the
species known to the writer from the strata between the Chico
and the true Tejon near Martinez, along with those which have
been collected elsewhere by Mr. Stanton, in beds of the same
age. A study of this list shows clearly that the fauna is a unit,
and that it is quite distinct from both the Chico and the Tejon,
though it grades to some extent into the latter.

The existence between the Chico and the Tejon of a fauna
not belonging clearly to either group, was evidently not unknown
to Gabb, and this fauna formed the real basis of his Martinez.
Unfortunately the involved stratigraphy led him or his col-
lectors into the error of supposing that certain Chico forms
belonged in the same horizon with Martinez species, while the
first error led to a second, viz., the belief that, since Chico forms
were present in his Martinez fauna, the whole group might be
found later to represent a subdivision of the Chico. As has
been shown in the comparison of faunas, there can be little doubt
that the Chico group is widely separated from what is here
called Martinez.

In considering the relations of the Martinez to the Tejon, it
might be well to determine first what was intended in the origi-
nal definition of the Tejon group and what it really is. The
name was proposed by Gabb on faléontological grounds tor a set
of rocks, supposed by him to be Cretaceous, but now generally
regarded as Eocene, ‘‘most extensively developed in the vicinity

GEOLOGIC: RELATIONS OF THE MARTINEZ GROUP 773

THE FAUNA OF THE MARTINEZ GROUP WITH GEOLOGICAL RANGE
OF THE SPECIES.”

3 yy
glels g|=\g
| Neil = 2) eS
6s /a 6\2\a

1 Foraminifera Nummuloid .. as 36 Dentalium stramineum Gabb| * | * | *

2 Foraminifera 3 sp. Indet..... Bo JOpxAN Agee il, Sonn be Soon Se Fe *

3 Flabellum Remondianum 38 LFicopsis sp (near Remondz)... * |

Gabbi.cehincone POET ane ene *|%* || 39 Fusus n. sp (2) *

A JAKES GUE MG Gs 60006 o0a55¢ * 40 Fususn.sp. (6).... *

5 SHOOT? ((@)) tls Sos 6000555050 * 41 Heteroterma Gabbi Stanton. 7

6 Terebratula tejonensis Stanton * 42 Heteroterma striata Cramtonte *

ORV BO ORA SROC AC SAnS Gc * 43 Heteroterma trochoidea Gabb.| |(?)

8 Cardita Hornii Gabb........ of (irl 44 indete mows.s-icia vette siete *

9g Cardium Coopert Gabb....... *|+ || 45 Leanatia Horniti Gabb. ..... ie
10 Crassatella untotdes Stanton .. * 46 Megistostoma striata Gabb... + *
It Cucullea Mathewsoni Gabb.. . ce 47 Morio sp. tuberculatus?...... 0 fs
12 Leda aleformis Gabb.......- * fils) INGER I 5 5c2 080 onseccoubS
mewiena (Gace Conkeee se eer * 1% || 49 Meptunea mucronta Gabb.... co
14 Lima multiradiata Gabb..... * 50 Perissolax Blaket Conr. nov.

15 Lucina Turneri Stanton..... * Vial eae te craetteterersierach ok: *
MW OMAVICTELP2IGES Dat ohelstahewel etal hee Ret eNal a 51 Szphonatia lineata Stanton. *
0G) MMGTQIORN, Sos coonc eh da coat * 2D SOMALTE Do FD) 555 0000 00006 *
18 Modiola ornata Gabb........ T|* || 53 Stripstdura pachecoensis Stan-

19 Nucula truncata Gabb...... * | ok | OMe Sis tate epersysney cater wre iets *
20 Pectunculus Veatchi var. major IN AOI Me So ((@)) Boos 480 a

Stanton s.\.2 40 anon reer * Be Manone (2) ily Sth (hacen a

21 Pholadomya nasuta Gabb..... * 56 Turbinella crassitesta Gabb .. =
22 Plicatula ostreiformis Stanton * 57 Turritella infragranulata
DEM SGLC7L PINS Dietitian: - (CHllo)\ ¢ooanunet co auc eudd ce
24 Tapes quadrata Gabb (aff.)... *1%* 1158 Turratella pachecoensis Stan-
As THE, We Do osen acon doto0c * Loman essa terns shale vterens *
26 Tellinma Hornit Gabb........ 6 || 59 Lrritela D. Spi(P))-.% ‘0p
27 Tellina (?) esi Gabb. ae 0) AAS Ms FVoboee coeuoonn oc *
28 Teredo (?).. 2 onep nee pe ches 61 Urosyca caudata Gabb....... *
29 Thracia (2)n. sp yeitvaeynieeerae ee 62) Grasyea WS. seein ossieiss='- *
340), Alana? (3) a9 0oqa5 Gn6cboce = 12 AIP te SDne oo sooo noo as
31 Ampullina striata Gabb (conf) os 64 Crustacean remains, brachy- ois
32 Brachysphingus liratus Gabb. * UITATNS ser ovroyessartePonvsy say sareysretec ohare» ie
28) JSUT (2) Ty Soaes co6506 * 65 Crustacean remains, macruran
34 Cylichna costata Gabb........ WES WO Waele oc saccocgasooceacee
35 Dentalium Coopert Gabb..... 203 || Ets

of Fort Tejon and about Martinez.’ It was stated? to contain
“a large and highly characteristic series of fossils, the larger

part peculiar to itself, while a considerable percentage is found

tAn asterisk indicates common or characteristic; a dagger, rare or characteristic
of some other horizon.

?Rep. Geol. Surv. Cal. Paleontology, Vol. IT, p. 13 of Preface.

774 JOHN C. MERRIAM

extending below into the next group, and several species still
farther down into the Chico group.” Since Gabb’s work was
published the Tejon has been recognized at numerous points on
the Pacific coast, outside the limits of its distribution as known
to him, and has always been found to contain an easily recog-
nized fauna, of which a number of the most common and char-
acteristic forms are found in the list of species from locality No.
5. As may be seen in the last quotation, the true relation of
the Martinez to the Tejon, as shown by the partial mingling of
species, was not unknown to Gabb.

In the vicinity of the town of Martinez, the Martinez and
Tejon groups form an apparently conformable series between two
and three thousand feet in thickness and about equally divided
between the two. The faunas, though overlapping, are in the
main quite distinct and no great difficulty has been experienced
by the writer in separating the groups on this basis. While some
intermingling of species exists, it is not greater than we should
expect to find in adjoining groups or periods. It should also be
observed that the beds with a Tejon-like Martinez fauna and
those containing an assemblage of characteristic Tejon forms are
comparatively close together. The change from one fauna to the
other may possibly have taken place in a short time by migra-
tion, but we cannot assert positively as yet that the apparent con-
formity of the beds is a real one, sedimentation may have been
interrupted between the times of deposition of the two groups.
It is at any rate quite clear that the two sets of strata, or two
faunas, while belonging perhaps to the same series, represent dif-
ferent periods in the geological history of California, periods
quite as distinct, so far as faunal evidence is concerned, as the
Miocene and Pliocene, or the Pliocene and Quaternary. The
upper division of this series has already, on the grounds of its
characteristic fauna, been named the Tejon. Toa mixed group
of rocks, to which the fauna here called the Martinez gave indi-
viduality, the name Martinez group was applied by Gabb. Itseems
desirable, after having cut out the Chico portion of Gabb’s Marti-
nez which was probably not the one on which he based the group,

GEOLOGIC RELATIONS OF THE MARTINEZ GROUP 775

to apply the name used by him tothe distinct fauna or group which
remains. As to the nomenclature of the supposedly conforma-
ble series, including the Martinez and Tejon, it seems best to
apply to it for the present the term Martinez-Tejon series, though
future convenience may demand a special series name. To apply
the name Tejon to the whole series would be to modify consid-
erably the meaning of this term as used originally, and would
have besides the fault of taking the name from a smaller division
to apply it to a larger, leaving the first to be virtually renamed.

In conclusion, the group under consideration might be char-
acterized as follows: The Martinez group, comprising in the
typical locality between one and two thousand feet of sandstones,
shales, and glauconitic sands, forms the lower part of a pre-
sumably conformable series, the upper portion of which is formed
by the Tejon. It contains a known fauna of over sixty species,
of which the greater portion is peculiar to itself. A number of
its species range up into the Tejon and a very few long-lived forms
are known to occur also in the Chico. Since the Martinez and
Chico are faunally only distantly related it is probable that an
unconformity exists between them. Though satisfactory corre-
lation of Californian formations with the subdivisions of the
standard geological scale can be accomplished only when the
local scale is fully worked out, we may, for the present at least,
accept Mr. Stanton’s correlation of the Martinez with a portion
of the Eocene.

Joun C. MERRIAM.
BERKELEY, CALIFORNIA.

SIGIDIUBS JON) Wels SOLGAOUISID IPOS NISIINUG (GaN aISs:
OF NEW HAMPSHIRE. II.

Contact Metamorphism.— The endomorphic changes wrought
by the granite intrusions are relatively slight. Thus the biotite-
gneiss and hornblende-gneiss southwest of Lake Wakawan have
the same mineralogical composition at the contact as they have
a quarter of a mile away from it along the strike. On Spindle
Point, gneisses of like nature show the only exomorphic change
discovered throughout the whole terrane of the Lake Winnipi-
seogee gneiss. Yet even this is a doubtful case, since the only
evidence is the presence of some sillimanite needles and a few
garnets in the schist near the granite. Again, the interbedded
biotite-gneiss, muscovite-biotite-gneiss, and actinolite-gneiss, at
the outlet of Little Squam Lake, are practically unaffected by
the granite. The same is true of the large biotite-gneiss-inclu-
sion on the north side of Beech Hill, as well as of the whole
contact-line of the Montalban group.

The schists on Saddle Hill exhibit the best metamorphic belt
which appears in the Winnipiseogee area. Specimens of the
country-rock were taken at localities from one to eight hundred
feet from the contact, and in all of them the country-rock proves
to be a typical muscovite-biotite-schist with accessory sillimanite
in long needles. Inside that zone toward the granite, however,
a pronounced metamorphic aureole encloses phases of the ter-
rane which represent important modifications of the schist. One
of them, some eighty feet from the contact, is a hornfels largely
made up of zoisite and andalusite (?) with quartz and magnetite.
Another, four feet from the granite, is a compact mica-schist
richly charged with garnets; while within five inches of the
contact this garnetiferous schist has absorbed a large amount of
orthoclase and plagioclase which seem to have been derived

from the neighboring granite.
776

SO-CALLED PORPAWRITIC GNETSS QF INEW HAMPSHIRE 777

The Ashuelot area is even more nearly devoid of distinct
zones of contact-alteration. Several suites of specimens were
taken across the marginal belt of schists at several different
localities, but in none of them was a definite alteration of mineral
content observable, as one goes toward the igneous rock. While
the Coés schists are highly garnetiferous at the contact, they
are often just as metamorphic in habit a mile or more from the
granite. Interlaminated actinolite-schists are abundant among
the common mica-schists of the area. They show no change at
the contact. The Bethlehem gneiss is often garnetiferous, and
in some slides the garnets are seen to be larger and more idio-
morphic near the granite than away from it. Apart from this
fact, one would not suspect from an inspection of the marginal
alterations that the porphyritic granite was once an igneous body
intruded in these same rocks in a molten state.

Finally, it would be difficult to point to any particular part
of the Main area as exhibiting metamorphic phases in the schis-
tose country-rock of the porphyritic granite which could not
have been produced before the granite was erupted. One
hundred and fifty feet from the great Greenfield sheet a typical
quartz-garnet-hornfels can be found, but from that rock to the
granite one passes over the typical biotite-muscovite-schist of
the region. The latter itself may be garnetiferous. It does not,
however, differ from similar phases of the ferruginous rocks
several miles from the contact. North of Henniker there out-
crops another hornfels at a contact with a prophyritic granite
apophysis and about 50 feet from the molar contact. It is a
compact aggregate of quartz and garnet with a large admixture
of a colorless pyroxene and a little accessory plagioclase and
muscovite. Notwithstanding this kind of association, these and
other examples cannot as yet with safety be considered as con-
tact phases, nor do they afford positive evidence of an eruptive
origin for the porphyritic granite.

The small amount of exomorphic change in the contact-belt
is that which might be expected from the conditions of the erup-
tions. It is well known that, other things being equal, acidic

778 REGINALD ALDWORTH DALY

igneous rocks are less likely to be altered by intrusive masses
than are the more basic rocks. In the same way sedimentary
rocks are in general more susceptible to contact metamorphism
than the crystalline chists or than igneous rocks.* Pohlig noted
important differential effects of the trachyte in the Siebengebirge.
Fragments of gneiss enclosed in the eruptive rock were rela-
tively unchanged as compared with inclusions of clay-slate in
which andalusite and other metamorphic minerals were devel-
oped.? Lehmann has described granulite inclusions in the gra-
nite of Markersdorf which he found to be entirely unchanged by
the granite.3 No student of contact-belts needs, however, to be
reminded that in them there is pronounced selective metamor-
phism depending upon the nature of the rocks invaded. Those
which have advanced furthest in the direction of mineralogical
stability will usually be the rocks which are least altered. IH,
then, there had been regional metamorphism of the country-rock
before a given intrusion occurred, such terranes will tend to be
without distinct zones of alteration. Such is the case with the
New Hampshire rocks. In the sequel the chief evidence for this
conclusion will be given, but we can anticipate somewhat by
stating the fact that the same series of schists which are cut by
the porphyritic granite are just as thoroughly crystalline many
miles from the porphyritic granite as they are in its immediate
vicinity. Moreover, they attained this crystalline character in
the process of mountain-building and not by any kind of local
thermo metamorphism induced by underlying areas of the por-
phyritic granite.t The eminent schistosity of these rocks was
anterior to the granitic intrusion, and it is an effect concomitant
with the recrystallization. Thus it was a series of terranes already
regionally metamorphosed that were cut by the porphyritic gran-
ite. They had reached a state of approximate mineralogical
equilibrium and but little rearrangement of the constituent
elements was possible by mere contact action.
*Cf. HUDLEsTON, Address Pres. Geol. Soc., 1894; Q. J. Geol. Soc., p. 121.
?Tschermak’s Mitth., 1880-1, p. 353.

3 Untersuch. iiber die Entsteh., der altkryst. Schiefergesteine, 1884, p. 7.
4Cf. BARROW, Q. J. Geol. Soc., 1893, p. 352.

SO-CALLED PORPHYRITIC GNEISS OF NEW HAMPSHIRE 779

Moreover, at Fitzwilliam, where the inclusions of the neigh-
boring biotite-gneiss are extremely well exposed, there does not
seem to be the slightest change in the horses. Yet there can be
no doubt that the porphyritic granite is here distinctly eruptive
in the gneiss. In the same way, the ancient granitite described
on the west and northwest of the village of Antrim has produced
no material alteration in the composition of the schist inclusions,
for in that feature they are identical with their parent terrane for
several miles from the contact.

It seems reasonable, then, to conclude from the brief account
of exomorphic contact-phenomena just given that they do not
invalidate the argument for the porphyritic granite’s being erup-
tive. It means that the conditions were not such as to permit of
the development of the well-marked metamorphic aureoles which
one might expect in invaded terranes composed of relatively
unaltered rocks.

Endomorphic changes — More often than not where the actual
contact between the porphyrictic granite and the older forma-
tions appears, there is practically little change either in the
composition or grain of the granite. This fact is characteristic
of apophyses as well asof the mainbody. Inthe Winnipiseogee
and Main areas particularly, the feldspat phenocrysts and their
matrix are remarkably persistent in the size of individual min-
erals. The reader will remember that a broad band of the
porphyritic granite with rare phenocrysts appears on the western
side of the Ashuelot area, and again that, on the eastern side,
there is evidence of fine-graining in the Bethlehem gneiss-contact
which can hardly be explained except as belonging to a chilled
phase of the igneous rock. It is true, however, that this phe-
nomenon is, on the whole, rather the exception than the rule in
the different areas. We cannot but think that the invaded
schists must have been at a high temperature themselves when
the granite was intruded. Witness the widespread zones of
passage between the two. The great coarseness of the matrix
shows that the granite was long in crystallizing and in that
process would naturally lose much heat to the surrounding rocks.

780 REGINALD ALDWORTH DALY

Thus the latter could not in the final stage of consolidation
cause a serious differential cooling in the marginal part of the
granitic magma. That there was some influence exerted upon the
igneous rock is indisputable. Almost universally thin sections of
the contact-zone exhibit a very marked granophyric intergrowth
of the quartz and feldspar of the matrix. This micrographic
development is quite independent of that noted as common about
the phenocrysts, and is quantitatively much superior in value to
the latter. The occurrence of the graphic structure in the matrix
is usually restricted to the contact-zone of not more than a few
inches or feet in width. It is noteworthy, however, that in parts
of the Ashuelot area where there are evidences of some crush-
ing, this structure is found in various parts of the coarse matrix,
though far from a contact. It doubtless originated as a result
of rearrangement during the period of stress which the rock has
here undergone. :
The origin of the foliation in the porphyritic granite —It is now
well established that gneisses may belong to three classes which
in the words of Gregory’ may be named metapyrigen-gneisses,
clastic-gneisses, and fluxion-gneisses. The first kind is produced
by the pressure-metamorphism of igneous rocks, the second by
the complete alteration of sediments. The third division has its
origin in molten rock-magmas which have undergone ‘fluxional
movements anterior to complete consolidation in a mass not
perfectly homogeneous.’? The porphyritic granite of New
Hampshire owes its foliated structure to the same cause as that
of fluxion-gneisses. Inshort, this porphyritic gneiss is a porphy-
ritic granite with a flow-structure. The parallelism among the
constituents was assumed when the rock was not yet fully
crystallized out and cannot thus be referred to any metamorphic
result of mountain-building acting on an already solidified mass.
It is a primary structure. Since this fact is not as yet demon-
strated in what has been said, and since we are dealing with a

™Q. J. Geol. Soc., 1894, p. 266.
?'T. G. BONNEY, Some Notes on Gneiss, Geol. Mag., 1894, p. 118. Cf. Hitt and
BONNEY, Q. J. Geol. Soc., 1892, p. 137.

SO-CALLED PORPHYRITIC GNEISS OF NEW HAMPSHIRE 7381

great terrane characterized everywhere by this foliation which
has been the subject of serious misapprehension among early
investigators in the state, we shall go into some detail to establish
this position.

It was not until the next generation after von Buch* described
flow-structure in lavas that the phenomenon was studied with
reference to the origin of gneisses. Scrope? in 1840 and Dar-
win3 in 1844, closely followed by Naumann,‘ first laid emphasis
on the truth that ‘dragging movements” on a cooling granitic
magma may lead to the formation of gneiss. Since that time, a
host of observations have confirmed their idea so completely
that it is now possible to frame the most important criteria which
ought to be applied to a problematical case, and, if satisfied,
should enforce belief in the gneissic structure of that particular
instance being of fluxional origin. It is proposed to consider
briefly these criteria with respect to their validity and to their
relation to our particular problem.

I. Since the fluxion-structure is due to differential stress, we
should expect some parts of a mass, to display a greater excel-
lences of the foliation. thames others.” “here wall) be zones of
relatively rapid movement and zones of more static conditions ;
at least during the geological movement of final consolidation.
Thus, we may expect to find transitions from trendless granite
to well-foliated granite or gneiss.5 We have already seen how
abundantly this change is exemplified in all the areas of the
porphyritic granite. Both of the State Surveys noted this rela-
tion between the massive and foliated phases.° The earlier one
seized upon the former as indicating simply a granite, the second

tGeognost. Beobacht. auf Reisen durch Deutschland und Italien, 1809, II, p. 209.

2Trans. Geol. Soc., 2d ser., II, p. 228.

3 Geological Observations, etc., Ist ed., 1844, ch. iil.

4Neu. Jahrb., 1847, p. 297. Q.J. Geol. Soc., Notices of Memoirs, p. I.

5 MICHEL LEvy, Bull. Soc. Geol. de France, 1878-9, p. 852. McMauon, The
Gneissose-Granite of the Himalayas. Geol. Mag., 1887, p. 214. Jézd., 1888, p. 63.
HARKER and MARR, The Shap Granite, etc. Q. J. Geol. Soc., 1891, XLVII, p. 284
EMERSON, Bull. Geol. Soc. Am., I, 1890, p. 559.

© Note, Geol. of New Hampshire, Vol. II, p. 99.

782 REGINALD ALDWORTH DALY

survey regarded the non-foliated parts as fused parts of a series
of altered sediments.

2. The parallel structure ought to be best assumed along the
contact, because there the essential condition of an appropriate
viscidity will be assumed within a zone which has a dominant
trend. Where the interaction effects of more than two cooling
surfaces meet, as they do in a mass of considerable breadth,

there is a tendency towards the obliteration of parallelism
induced in any one zone of chilling at a plane of contact. Con-
vection currents will further complicate the flow-structure and to
a greater extent in the hotter core of an intrusive mass than in
the chilled zone. For these reasons parallelism among the con-
stituent minerals should be most clearly exhibited along the
boundaries where the structure-planes of the igneous mass will
accord in direction with the plane of contact. The central area
may either lose any incipient foliation or show sudden irregular
changes of strike and dip of fluxional planes which do exist. In
other words, wherever else it may appear, the fluxional struc-
ture is to be looked for chiefly at the margins."

™ BROGGER (Die Silurischen Etagen 2 und 3; Kristiania, 1882, pp. 325, 326),
describes the endomorphic zone of contact of his granitic and syenitic eruptives as
possessing a parallel structure “wodurch gestreifte Gesteine, bisweilen wie echte

krystallinische Schiefer aussehen. It is parallel to the irregular boundaries of the
igneous rocks.

McMahon, Note on the Foliation of the Lizard Gabbro; Geol. Mag., 1887, p. 76.

BARROIS states that inthe granulites of Morbihan the parallelism is most perfect
when the contact-line is in the strike of the enclosing strata. In such parallel con-
tacts, the granulite is apt to change to a “granulite porphyroide, a grands éléments,
alignés fluidalement.” In “contacts perpendiculaires”’ the rock has an aplitic phase
in which the crystalline constituents have regular geometric forms. He considers
that such differences in the intruded granite depend on the country-rock as an agent
chemically inactive but ‘“‘diversement conducteur de la chaleur et de la pression.”
Sur les modifications endomorphes des massifs granulitiques du Morbihan ; Comptes
Rendus, CVI, 1888, p. 428.

GEIKIE, A., The History of Volcanic Action during the Tertiary Period in the
British Isles ; Trans. Roy. Soc. Edin., 1888, p. 37.

BARLOw, On the Contact of the Huronian and Laurentian Rocks North of Lake
Huron, Am. Geol., VI, 1890, p. 22.

SMITH, W. H.C., Ann. Rep. Geo. Surv. Canada, 1890-1, map.

GReEGorRY, J. W., The Waldensian Gneisses and their Place in the Cottian

SO-CALLED PORPHYRITIC GNEISS OF NEW HAMPSHIRE 783

The reader will remember how often this principle was illus-
trated in our detailed account of contact-phenomena. It
undoubtedly explained the greater perfection of the foliation in
the long and narrow Winnipiseogee area than that in the
broadly eliptical Ashuelot area or Main area. At the Benning-
ton reservoir in the large size of the feldspar phenocrysts and
their definite orientation with respect to the adjacent contact
we have a good example of what characterizes the endomorphic
zone of the Main area throughout the eastern contact as
mapped. Within the zone the structure is much less determi-
nate. Again, on Sandwich Mountain the porphyritic granite in
and about the ‘‘permeation-area’”’ described above, is largely
granitic with the exception of those parts which display the
fluxional habit about the horses. We are not without sugges-
tion that the sudden changes of dip and strike within the cores
of the igneous masses are largely the result of convection act-
ing with massive pressure in the still viscid rock-body. Two
miles from Weirs, on the highway to Meredith village, several
outcrops appear in a clear field some three hundred yards to the
right of the road. At one of these, a well-marked anticlinal
arrangement can be observed in typical porphyritic granite.
This structure is not part of a general system of parallel folds,
nor of folds with any recognizable relation to the behavior of
solid rock acted upon by lateral force. It is rather to be cor-
related with the irregular flow-structure assumed in the internal
parts of many rhyolites; the well-known “ felsites”” of eastern
Massachusetts furnish a good example."

3. An analogous appearance will tend to characterize the
margins between the intrusive rock and any foreign bodies which
Sequence ; Q.J. Geol. Soc., 1894, p. 249. On page 265 the author says of the folia-
tion in these Alpine gneisses that it is “‘ a contact-fluxion, and has no connection with
the dynamo-metamorphism of the district. Thismarginal orientation also occurs on a

microscopic scale. Mr. C. L. Whittle has described good examples in the contacts
of the Connecticut Triassic lavas.

BONNEY, T. G., Some Notes on Gneiss; Geol. Mag., 1894, p. 118.

”

Cf. MEHNER, “ Fluctuationstructur” described in certain of “die schiefrigen
Porphyren” of Westphaiia ; Tsch. Mitth., 1877, p. 177.

784 REGINALD ALDWORTH DALY

are caught up from the surrounding terranes.t In many cases,
however, it is due not only to differential cooling, but to the
pulling of the horses along in the direction of the migrating
viscid magna. Such is the case with the examples of the cir-
cumferential arrangement of feldspars noted on Sandwich
Mountain, on Saddle Hill, and in the Fitzwilliam area, and else-
where.

4. Many observers have described the orientation of horses
parallel to the margins of contact in cases where the inclusions
have distinct elongated form.? The latter condition is usually
furnished in the case of fragments derived from a country-rock
with plane-parallel-structure. Consequently, we can understand
this very general marginal arrangement described in all of the
principal areas.3 i

5. The greater the heterogeneity among the constituents of
the igneous body at the time of proximate consolidation, the
more pronounced will be the flow-structure. As suggested by
Bonney,* horses may be melted up and thus give local variations
in the mineralogical constitution of the igneous body. ‘‘ Band-
ing’’ is sometimes produced by the imperfect mixing of more

tLawson, The Geology of the Rainy Lake Region; Ann. Rep. Geol. Surv.
Canada, 1887-8, F’, 137-138. BARLOW, op. cit., p.29. DAKyYNs and TEALL, On the
Plutonic Rocks of Garabal Hill and Meall Breac; Q. J. Geol. Soc., 1892, p. 106.

Koto, B., The Archean Formation of the Abukuma Plateau; Jour. Coll. Sci. Imp.
Univ., Tokio, 1893, p. 288. GREGORY, Q. J. Geol. Soc. 1894, p. 242.

2 DUROCHER, Mém. de la Soc. Géol. de France, 2° sér., t. VI. See his descrip-
tions of several gneiss-granite contacts in Scandinavia; LEHMANN, Untersuchungen
tiber die Entstehung der altkryst. Schiefergesteine. Bonn, 1884, pp. 16, 21; GEIKIE,
A., op. cit., p. 39; GRANT, U.S., Field observations on certain granitic areas in north-
eastern Minnesota; 20th Ann. Rep. Minn. Surv., 1891, p. 40.

3Cf. EMERSON, Bull. Geol. Soc. Am., I, 1890, p. 559.

4Geol. Mag., 1894, p. 119. Cf. BONNEY, zézd., 1894, p. 118. C. CHELIUS has
recently described a stage leading to the complete fusion of enclosed masses, which is
of interest. In this case granite cuts diorite and includes so many lenses of the latter
in parallel arrangement as to simulate a “grobflaseriger gneiss.’’ Notizbl. d. Ver. f.
Erdk. Darmstadt, IV, Folge, 14 Heft, 3-8, 1893. Ref. in Neu Jahrb., 1895, p. 72.

J. J. SEDERHOLM speaks of “Schlieren” rich in mica and garnets in the “ druck-
schieferiger Granit” of Finland. They are taken to represent remnants of schist-
inclusions which have been dynamically metamorphosed. Om Borggrunden i Sodra
Finland, 1893. Ref. in Neu. Jahrb., 1895, p. 335.

SO-CALLED PORPHVYRITIC GNEISS OF NEW HAMPSHIRE 785

than one phase of a magma." It is conceivable that it might be
locally brought about by the pulling out of basic segregations
in a plutonic rock by mechanical force operating during or after
complete consolidation.

On the road along the north shore of Wickwas pond a strik-
ing phase of the porphyritic granite was found which had been
discovered before but never in such perfect development. It
forms a strongly schistose mass a few inches thick which lies
parallel to the foliation of the normal rock. Composed largely
of brown biotite with here and there a large feldspar phenocryst,
it is very different in appearance. With the biotite large apatites
and considerable masses of titanite and magnetite make up the
groundmass. This band had much the appearance of a shear-
zone, like that described in the crystallines of the Malvern Hills.”
But the microscope discloses no strong evidences of crushing in
the feldspars which are clearly original or primary in their nature.
Now there are plenty of cases on record where biotite segrega-
tions in granitic rocks grow to large size. Those at Graniteville,
Missouri, vary from a few inches to five feet or more in diameter.
It may be that this and similar local bands in the rock in question
are due to the tailing out of such segregations before the final
solidification of the whole rock had set in. The resulting bands
would thus be parallel to neighboring structure-planes and take
their place as primary elements in a fluxional mass.

But the most favorable chance for the exhibition of a parallel
structure over large areas would be given in cases where there
is more than one generation of minerals; 7. ¢@., in porphyritic
rocks. Such, indeed, has been the character of most of the plu-
tonic rocks where extensive flow-structure has been described.
The large size of the phenocrysts of the porphyritic granite is one
of the chief conditions leading to this peculiar and widespread
foliation. Possessed of large growth before the final magmatic
crystallization set in, each feldspar phenocryst was, as it were,

*HARKER and MARR, Q. J. Geol. Soc., 1891, p. 283; A. GEIKIE and TEALL,
ibid., 1894, p. 656.

© Geol soc. 1580s pai4i7 7
3Geol. Surv. Missouri, Ann. Rep., VIII, 1894, p. 154.

780 REGINALD ALDWORTH DALY

of the nature of a foreign body embedded in the matrix. Thus,
it would behave in the same manner as the truly exotic inclusion
and a conspicuous alignment would result. It was observed in
the field that, as arule, the greater the dimensions of the pheno-
crysts, the more clearly was the structure displayed.

It is clear that the porphyritic granite with its elongate
feldspar phenocrysts abundantly fulfills this criterion. In fact,
the study of it suggests that plutonic rocks would more generally
show a flow-structure were their constituents more varied in
shape and relative size from the usual forms.

Quite rarely a broad banding is observable which is the result
of the juxtaposition of layers containing different proportions
of the phenocrysts."

6. The negative criterion is valuable and in this New Hamp-
shire case is most conclusive. If it canbe shown that mountain-
building could not induce the parallel structure in any secondary
fashion, z. ¢., by the pressure-metamorphism of consolidated,
igneous or sedimentary rocks, we can fairly assume that the only
other recognized cause has been operative. The evidence
necessary therefore is threefold.

First, it may be derived from the study of foreign inclusions.
The schistosity of the horses in all the observed localities where
they occur within the porphyritic granite was evidently produced
before the existence of that rock in its present state of crystalliza-
tion. In practically all cases where comparison was possible,
the excellence of this structure in any one inclusion was reflected
in its parent-terrane. As the one varied from massive to
schistose with a high degree of fissility, so did the other. Now
the perfection of the schistosity was found to be irrespective of
the attitude of the horses, z. e., whether they were in parallel
arrangement or not. Callaway used the correlative of this
principle as an aid in determining the nature of the foliated
granites of Northern Donegal.*? He finds in them inclusions of
massive diorites. His conclusion is, that on any theory of a

*Cf. G. H. WILuiAMs, Bull. U. S. Geol. Surv., No. 28, p. 26.

? READE, Origin of Mountain Ranges, p. 139.

SO-CALLED PORPHVRITIC GNEISS OF NEW HAMPSHIRE 787

mechanical origin for the foliation, it would be “ hard to explain
the escape of the diorite inclusions from the same influence.”
But if the intrusion of the porphyritic granite followed the period
of plication and metamorphism, we should expect it to follow
commonly the structural planes of the preéxisting schists."
Again referring to our detailed description of contacts in the
three large areas, it will be seen how commonly this is the case.
The intrusions are batholitic in their nature. They entered the
overlying rocks by melting’ their way through the axial zones
of flexures. It is for this reason that the general distribution of
these granite bodies is along the strike of terranes in this part
of New Hampshire. The equivalence of strike and dip in the
region in the narrow part of the “ Fish-hook” north of Squam
Lake between the foliated igneous rock and the adjacent schists
is especially conspicuous.3. Such pronounced apparent conformity
is probably owing to an exchanging of the usual batholitic form
of intrusion for a sill or sheet-form.

Secondly, the study of apophyses will be of much conse-
quence. If we there see parallelism of the minerals composing
the intruded tongue to its walls, no matter what the compass-
direction of the apophysis may be, it is evident that the struc-
ture cannot be referred to mechanical deformation applied after
the cooling of the whole intrusive mass. Scheerer early

*See GUMBEL, op.cit., p. 522, 523, 524. He describes “‘ Lagergranite”’ intruded
into various schists. It is rather remarkable that his “ Krystallgranit ” of Bavaria does
not possess a decided flow-structure. The rock is very similar to the porphyritic
granite otherwise. Cf. also LAwson, Ann. Rep. Geol. Surv. Canada, 1885, CC, p. 73,
LEHMANN, op. cit., pp. 10, 23; WILLIAMS, G. H., Proc. A. A. A. S., 1887, XXXVI;
Sect. E, p. 225; CaLLaway, Geol. Mag., 1887, p. 354; Lawson, Ann. Rep. Geol.
Sury. Canada, 1887-8, F, p. 32; DANzic, Mitth. aus dem Min. Inst. der Univ. Keil
Bd. I. heft 1, 1888, p.66; BaRLOw, Am. Geol., VI, 1890, pp. 21-22; HARKER and

MARR, op. cit., p. 284; ADAMS, Jour. of Geol., 1893, p. 334: SMITH W. H. C., Bull.
Geol. Soc. Am., 1893, p. 338.
2 From the author’s previous statements there is no evidence that melting took

place in connection with these intrusions. [ED.

3See the map of Hunter’s Island by Mr. W. H. C. SMITH, which shows a very
remarkable parallelism of the foliation in his “ granite gneiss” with the strike of the
enclosing schists. Ann. Rep. Geol. Surv. Canada, 1890-1.

4Lawson, The Geology of the Lake of the Woods Region; Ann. Rep. Geol.

788 REGINALD ALDWORTH DALY

described an occurrence of the opposite of this.t_ He deter-
mined that the red gneiss of the Erzgebirge is plainly eruptive
into the gray gneiss. The apophyses of the former have a
distinct parallel arrangement among the constituents. It is,
however, not parallel to the walls, but inclined to them. He,
hence, concludes that it is due to pressure exerted after the
consolidation of the ancient granite.» That the apophyses
should be as coarsely porphyritic as the main body, is of itself
a strong suggestion of the exotic origin of the latter3 As
we have seen, such is the case with the porphyritic granite,
and in many instances, as on Saddle Hill, on Sandwich Moun-
tain, in the Greenfield dike, and at Fitzwilliam, the apophyses
have a more or less well-developed foliation, parallel to the
walls and transverse to the structure-planes of the schists.
Lastly, while the porphyritic granite shows in certain areas
evidence of strain, there is none of that very intense crushing
which might be looked for if the foliation were of a mountain-
built origin.4 The signs of pressure in some of the pheno-
crysts may be due to the shearing set up among them in the
tough, but still viscid magma, just on the instant of final con-
solidation. At the south end of the Ashuelot area we have
the most schistose phase of the rock. It has evidently been
squeezed to some extent. It is crumpled and even changed
to an augen-gneiss whose lenticular feldspars represent the
idiomorphic phenocrysts of the original rock.’ Small faults of
a half foot throw were observed in the Winnipiseogee area, just
Surv. Canada, 1885, CC. p. 83, Danzic, Ueber die eruptive Natur gewisser Gneisse

sowie des Granulits im sachsischen Mittelgebirge ; Mitth. aus dem min. Inst. der
Univ. Kiel. Bd. I, Heft 1, 1888, p.67. RruscH, Neu. Jahrb., Beil. Bd, V., Heft 1.
1887, p. 57.

tDie Gneisse des sachsischen Erzgebirge ; Zeit. d. d. geol. Ges., 1862, pp. 122-123.

2Credner attempted to prove that the red gneiss of the Erzgebirge is of sedi-
mentary origin and not eruptive, as held by von Cotta, Scheerer, Stelzner, and others.
Zeit. d. d. geol. Ges., 1877, p. 757.

3Cf. MCMAHON, Geol. Mag., 1888, p. 63; Q. J. Geol. Soc., 1893, p. 357.

4Cf. Lawson, The Geology of the Rainy Lake Region, Ann. Rep. Geol. Surv.
Canada, 1887-8, F, pp. 137-138.

5Cf. HAWEs, Geol. of N. H., III, p. 214.

SO-CALLED PORPHYRITIC GNEISS OF NEW HAMPSHIRE 789

north of Wickwas pond. But there is nothing to indicate that
any batholite as a whole has undergone any such enormous
stresses as have affected the anorthosite of Canada, the proto-
gine of the Alps, or even the gneisses of the Malvern hills.’
Under the microscope the New Hampshire rock always shows
that the essential minerals crystallized in place and that they
have only been affected, except locality, by moderate pressures.

From the complete satisfaction of these several criteria one
cannot escape the conviction that the foliation of the porphy-
ritic granite has nothing to do with stratification, and has not
been caused by the alignment of the constituents in a time of
pressure metamorphism acting on a consolidated rock.

The significance of the uniformity of the porphyritic granite and tts
wide geological distribution One of the most striking character-
istics of the porphyritic granite is the lithological sameness
which pertains to it to a great degree throughout all the areas
examined. This property is retained irrespectively of the nature
of the rock-terranes which it invades. From the many examples
of endomorphic changes induced in plutonic rocks by the melting
up of foreign inclusions, we have selected a few which are
described in the annexed footnote.” In view of this principle,

tT CALLAWAY, Q. J. Geol. Soc., 1887, p. 525.

2 Michael Lévy finds that by an endogenous action granulite cutting diabases and
diorites is enriched in plagioclase at the contact (Bull. de la Soc. Géol. de France
1882-3, p. 296). Lehmann states that where the granitite of Dobeln is intruded
into biotite-bearing rock, it is practically unchanged, but when it cuts in contact with
sericitic schists, siricite is an important constituent (Untersuch. tiber Ent. d. altkryst.
Schiefergesteine, Bonn, 1884, p. 19). Again, on classic ground, Lawson determines
his Rainy Lake eruptive rock to bea quartzose biotite-granite gneiss where it comes
in contact with quartz porphyries, yet the same rock-body cutting the more basic horn-
blende schists becomes a hornblende syenite with little quartz (Ann. Rep. Geol. Surv.
Canada, 1887-8, F, 31). In one of the great batholites of western Massachusetts, Emer-
son notes three phasal differentiations, a heavy hornblende granite, a hornblende gran-
itite, and a granite proper, all of which he attributes to the melting up of three
various sorts of crystalline schists respectively (Bull. Geol. Soc. Am., I, 1890, p. 559).
A similar affection of a porphyritic granite by a hornblendic country-rock is found in
Chor Mountain, India (Geology of India, 2d ed., by Oldham; Strat.and Struc., p. 43);
while quite recently Harker notes a good case of a relatively basic modification of
granophyre at its junction with gabbro, and ascribes it mainly to an incorporation of
re-fused gabbro (Q. J. Geol. Soc., 1895, p. 134).

790 REGINALD ALDWORTH DALY

it may be asked, why does the porphyritic granite not show more
variations of mineral content? To this question we have no
conclusive answer. It is possible that the rock which now fills
the areas of the porphyritic granite was in general not ata tem-
perature high enough to cause vigorous melting up of the walls,
and that the great spaces in the earth-crust now filled by the
granite were opened during the passage upward of earlier and
hotter parts of the same magna. However this may be, the dif-
ficulty remains just as great for any theory of a metamorphic
origin for the granite. It is impossible to believe that a rock
with such continuity of like characters should have resulted
from the alteration of the stratified or schistose rocks in the
accompanying terranes of New Hampshire. Although the deter-
minations of relative age among these terranes are as yet neces-
sarily imperfect, we know that the porphyritic granite is in
contact with rocks of many different horizons and of very varia-
ble composition. From this fact, it seems reasonable to con-
clude that the porphyritic granite is an exotic eruptive, finding
its source of supply elsewhere than in any metamorphic center
in immediate connection with the encircling schists. McMahon
lays considerable stress on this idea in his argument for an
eruptive origin of the Himalayan granites.‘ Lawson, in his
study of the Laurentian gneisses, and Barlow, in a similar prob-
lem among the ancient rocks north of Lake Huron,’ refer their

”

‘irruptive ’ masses to a fusion of the granitic floor on which the
post-Laurentian rocks were laid. The New Hampshire rock is
thus, in respect to its origin, more closely allied to the Hima-
layan granite than to the gneiss of the Canadian Laurentian.

Coarse veins cutting porphyritic granite— McMahon and others
describe plutonic eruptives intersected by dikes and veins of
very similar material to that of which their hosts are composed.
Besides the usual evidences of aneruptive origin for the Dal-
housie gneissose granite of northern India, McMahon adds a
criterion which is certainly without the weight of its associates,

™ Geol. Mag., 1887, p. 216; Rec. Geol. Sury. India, XVIII, 1885, p. 106.

2 Bull. Geol. Soc. Am., IV, 1893, p. 331.

SO-CALLED PORPHYRITIC GNEISS OF NEW HAMPSHIRE 791

but which has been recently used more than once. He states
that ‘the granite contains veins similar to those caused by
shrinkage on cooling in granites of admittedly eruptive origin.’’?
Emerson makes the principle more definite. Speaking of the
largest granitic intrusion in Massachusetts west of the Connecti-
cut River, he says: ‘The great mass is cut everywhere by a
very great number of dikes of a coarse muscovite-granite, which
seem to represent later intrusions of the central portions of the
mass into shrinkage cracks in the already cooled peripheral por-
tions, and thus to represent more truly its original composi-
tion.’’? This seems to be the best interpretation of those coarse
dikes cutting the porphyritic granite composed of large individ-
uals of the same minerals that make up that rock. They occur
everywhere, though there is a concentration of them along the
boundaries. With them are often associated the pegmatite
veins of variable mineralogical constitution of aqueo-igneous
origin and apparently without direct connection with the under-
lying magma.? On Gun Mountain, on Bear Hill, on the road
following the valley of Rixford brook, and in the eastern area
near New Hampton Centre, dikelike bodies of the former kind
transect the porphyritic granite. Such localities suggest that in
this respect also the main granitic mass is eruptive.

The age of the porphyritic granite—We have seen that the
porphyritic granite intrusions were posterior to the stress-period
during which the chief metamorphism of the New Hampshire
rocks was brought about. The position of the axis of flexure
determined largely the shape of the different important areas.
Each one is batholitic in its nature. Since the eruptions ceased,
no considerable deformation has occurred. In this, all the areas
are alike, and from other facts, too, they were without much
doubt essentially contemporaneous.

Now, the geologically highest fossiliferous zone within the

*Geol. Mag., 1887, p. 216.

? Bull. Geol. Soc. Am., 1890, p. 559. Cf. HARKER and Marr, Q. J. Geol. Soc.,
1891, p. 284.

3Cf. BARLOw, Am. Geol., VI, 1890, p. 29.

OZ REGINALD ALDWORTH DALY

mountain-built strata is the well-known one at Bernardston,
Mass., some seven miles to the southwest of the Ashuelot area.
The first studies of the organic forms enclosed in the limestones
at this place referred them to the Helderberg or lower Devon-
ian. More recent determinations now fix the age of the lime-
stones as being at the Hamilton-Chemung stage of the Upper
Devonian. They are folded up with quartzites and mica- and
hornblende-schists which are intensely metamorphic. The care-
ful field work of Professor Emerson and of the late Professor
Dana has shown that these metamorphic rocks are a part of the
same terrane which throughout this paper and the survey
reports of the New Hampshire survey has been called the
‘“Coés group.” As early as 1873, Dana concluded that “the
Bernardston, South Vernon, and Northfield beds being of Hel-
derberg age, the Coéds group, which is but the northern contin-
uation of the same series, is, if correctly traced out, also Helder-
berg.”’* Professor C. H. Hitchcock adopted this view, although
he disagreed with Dana as to the stratigraphic order of the
rocks adjacent to the limestones.?_ Professor Emerson followed
with the publication of his results after a painstaking lithological
and structural study of the whole area. In this paper he most
emphatically states his conviction and advances new proof that
Dana’s position was the correct one. Two years later Dana
reiterated his opinion,‘ and in his last and greatest work clearly
shows that it persisted for the rest of his lifes Professor Emer-
son is inclined to place the faults and folds which dislocate the
Bernardston rocks in Carboniferous or post-Carboniferous time.
He attains this result by combining his observations at Bernard-
ston with those in the more richly fossiliferous localities farther
south, in the state of Massachusetts. Thus we may conclude
that the porphyritic granite is probably a post-Carboniferous

t Am. Jour. Sci. (3), Vol. VI, 1873, p. 349.

2Am. Jour. Sci. (3), Vol. XIV, 1877, p. 380.

3 Am. Jour. Sci. (3), Vol. XL, 1890, pp. 263 and 366; especially p. 366.
4 [bid. (3), Vol. XLIII, 1892, p. 456.

5 Manual of Geology, pp. 310, 325.

SO-CALLED PORPHYVRITIC GNEISS OF NEW HAMPSHIRE 793

intrusive and certainly younger than the upper Devonian at any
rate.

Posterior to the schists, to the so-called protogines, and to
other old eruptives on the one hand, the porphyritic granite is,
of course, older than the aplitic and lamprophyric dikes which
intersect it. It is also older than the Fitzwilliam granite, the
hornblende granite stock of Mount Whiteface, the Franconia
breccia,* and probably older than the complex stocks of the
Waterville area. It is impossible with the facts now in hand to
go further in fixing an epoch for these great intrusions. The
porphyritic granite may even belong to the Tertiary.

SUMMARY.

Briefly stated, the chief conclusions which have been arrived
at in the foregoing pages, are as follows:

1. The so-called ‘ porphyritic gneiss” of New Hampshire is
at least in the three most important areas, an eruptive porphyritic
granite with a common tendency to develop planes of foliation.

It is not to be regarded as indigenous, that is, as the pure
fused product of the surrounding formations—a deep-seated
exotic origin must be posited for the granite. The evidences for
an igneous instrusive origin include the composition and struc-
ture of the rock itself, the study of field-relations, the fluxional
nature of the foliation, the uniformity of the rock in all its extent
and the prevalence of secondary dikes and veins of injection
apparently derived from the same magma. Besides _ these posi-
tive facts, there are also those embodied in what may be termed
negative evidence. It includes all those observations that have
been made in which the peculiarities of the region and of each
intrusion will explain why some of the usual criteria of eruptive
origins are not perfectly fulfilled. Chief among them is the fact
of small certain and undoubted metamorphic effects at contacts
— one which we have seen can be readily understood from the
characters of the invaded rocks. Lastly, the contacts at first
sight equivocal prove to be intrusive contacts on comparative

"Geolhrot Nei. Viol: ll, ps 257.

794 REGINALD ALDWORTH DALY

evidence. The existence of zones of passage between the por-
phyritic granite and the schists with which it comes in contact
is a fairly common phenomenon in the case of stocks of plainly
eruptive material. Such transitions then form no inherent
objection to a similar origin in this instance.

2. The intrusions necessarily took place under great depth of
strata. The latter were elevated by the last great period of White
Mountain flexure and were practically holocrystalline products
of the consequent metamorphism before the porphyritic granite
was intruded. The subsequent disturbance of the greatest inter-
est to us in this connection is that which caused the porphyritic
granite to assume the parallel structure of flowage under differ-
ential stress analogous to that of the Himalayan and Alpine
central granites. Since that time, the force operating on the
terranes has been relatively slight. It has not sufficed to rub
out completely, in any part, this initial structure of the por-
phyritic granite.

3. The molten rock entered the overlying schists in an irreg-
ular fashion but in general followed the regional line of strike of
the White Mountain district.

4. Various considerations lead us to believe that the three
areas of porphyritic granite described are virtually contempo-
raneous. They are, in every case, post-Devonian in age, — how
much younger is unknown. Not being a basal formation, the
terrane loses much of its value in an elaboration of the strati-
graphic sequence and areconstruction of the New Hampshire
geological scale is necessary.

5. The porphyritic granite adds its testimony to the value of
the opinion recently formulated among geologists that a highly
important class of gneisses owes its parallel structure to fluxional
movement. And it has the other general kind of interest in
exemplifying the truth of Barrois’ prophecy ‘‘que les terrains
paléozoiques sont destinés a s’étendre de plus en plus sur les
cartes géologiques aux depens des terrains primitifs.”’

REGINALD ALDWORTH DALY.

HARVARD UNIVERSITY.

SUPPLE MENTE eeyY POTHESIS. RESPECTING, THE
ORIGINSOPS THE, LOESS OF THE sMISSISSIPE!
VALELENE:

Tue loess problem still remains obstinate. While it has
yielded somewhat to progressive research, there is, I think, a
nearly universal feeling of dissatisfaction with all theories thus
far advanced. The eolian hypothesis appears to be the better
supported so far as concerns the chief deposits of China and
perhaps some of those of western America, while the aqueous
hypothesis seems best supported so far as concerns the deposits
of the Mississippi valley and western Europe. It is the judg-
ment of some students that the ultimate solution will lie in the
recognition of both hypotheses, but the means of discriminating
between the two and of applying the criteria are as yet wanting.
The present paper is intended to be a contribution in this direc-
tion. It is confined to the loess deposits of the Mississippi
valley, but is probably applicable to the loess of western Europe.

The distribution of the loess in the Mississippi valley seems
to be very significant inits peculiarities. These may be summed
up in two great features.

1. The loess is distributed along the leading valleys. These
embrace not only the great valleys, the Missouri and the Mis-
sissippi, but some of the subordinate valleys, as the Illinois, the
Wabash, and others. The loess is found along the Missouri
River from southern Dakota to its mouth; along the Mississippi
River from Minnesota to southern Mississippi ; along the illinois
and the Wabash from the points of their emergence from the
territory of the later glacial sheets to their mouths. Along
these valleys the loess is thickest, coarsest and most typical in
the bluffs bordering the rivers and grades away into thinness,
fineness and non-typical nature as the distance from the rivers

tRead before Section E, Am. Asso. Adv. Sci. Aug. 12, 1897.
795

796 T. C. CHAMBERLIN

increases. In some instances the loess mantle rises to the divide
and connects with the similar deposit of an adjacent valley, but
the law of progressive fineness and thinness still holds. This
relationship is such as to create a very strong conviction that
the deposit of the loess was in some vital way connected with the
great streams of the region.

2. The second significant feature is the distribution of the
loess along the border of the former ice-sheet at the stage now
known as the Iowan. (Strictly speaking there was more than
one stage of loess formation, but for convenience only the main
stage will be here discussed.) The elaborate paper of McGee
made us familiar some years ago with this relationship in eastern
Iowa. The studies of Calvin and his colleagues, Bain, Beyer, and
Norton, of the Iowa Survey, of Winchell and Upham of the Min-
nesota Survey, of Todd of the South Dakota Survey, and of Salis-
bury, Leverett, Udden, Buell, Hershey, and the writer of the
United States Survey, have greatly extended the evidence of this
relationship. It has recently been much advanced by the Iowa
geologists and by Leverett and Hershey in northwestern IIlinois.
Next the border of the ice-sheet the loess is thick and typical,
but graduates away with increasing distance from the ice border
ina manner similar tothe graduation away from the river valleys.
On the border next the ice there are developed the formations
designated by McGee paha, elongated domes of quasi-drumloidal
_ contours which are mantled by loess. This superficial loess grad-
uates downwards into loess of coarser and coarser texture until
it often passes into a nucleus of sand. Below this there is often
an embossment of till. These pahas seem to be ice border phe-
nomena. Whatever their special mode of formation their distri-
bution seems to connect them in some more or less direct genetic
relationship with the ice.

It has been affirmed by several independent observers that
the loess graduates into glacial clays and glacial till and this
relationship further tends to confirm the association of the loess
with glacial action.

It has been shown by the microscopical examinations of

ORIGINGOR THE LOESS OF THE MISSISSIPPI VALLEY °797

Salisbury that the loess particles are composed in part of feld-
spars, amphiboles, pyroxenes and other common constituents of
the glacial clays. These silicates are decomposable under pro-
longed weathering, and hence cannot well be supposed to come
from residuary clays under the ordinary conditions of the Mis-
sissippi valley. The presence of the calcium and magnesium
carbonates, independent of the presence of shells, points in the
same direction. This inference is strengthened ina peculiar way
by observations in the lower Mississippi valley. Above the
Lafayette gravels and below the loess there is a stratum of silt
which does not habitually contain the characteristic silicate
particles of the loess. This stratum has been by most observers
associated with the loess, but it is separated from it by a soil
horizon as abundantly affirmed by the observations of Salisbury .
and the writer. On the other hand it graduates more or less
freely into the Lafayette sands and gravels. The stratum is,
as we interpret it, the last deposit of the Lafayette stage. It is
a typical finishing deposit succeeding a fluvial sand and gravel.
Now this has special significance in this relationship, in that it
shows that in the stage closely preceding the loess deposit, the
Mississippi did not lay down silts of the same constitution as
the loess. The inference therefore is that the loess is not simply
a fluvial silt brought down from the surface of the river basin,
nor common wind drift borne into it, but that it had a special
origin connected with glacial action which was competent to
supply precisely the kind of silt of which the loess is made.

It is hard to resist the force of this argument from the con-
stitution of the loess taken in connection with the two distribu-
tive relationships. Jointly they seem to force the conviction
that the loess had its origin in some relationship to the ice of
the Iowan stage and to the rivers that led away from the ice
edge at that time.

But the hypothesis that the loess is simply an outwash of
glacial grindings distributed along the river valleys by the
glacio-fluvial waters is attended by grave difficulties. This
remains true whether the deposition be supposed to have taken

798 T. C. CHAMBERLIN

place either in a strictly fluvial fashion, or in a fluvio-lacustrine
fashion, or in a true lacustrine fashion, or in an arm of the sea.
In the first place, the vertical distribution of the loess cannot
easily be explained. The extreme vertical range is not far from
a thousand feet. The range within a score of miles is frequently
from 500 to 700 feet. The loess sometimes seems to the field
observer to have a special fondness for summit heights. It
sometimes mantles topography of a pronouncedly rolling type.
It does not then appear to be a deposit which once had a level
or even a smooth surface out of which the rolling surface has
been eroded, but to be a mantle laid down upon a previously
undulatory surface. Such a mantle might perchance be laid
down from water, but I am not aware that we have any demon-
strative deposition of the kind which closely simulates the
mantling of the loess in some of the upland territory. To sup-
pose that the Mississippi, Missouri, Illinois, Wabash and lower
Ohio rivers were so swollen that they united over their divides
and threw down a mantle of fine silt over the southern and
western half of Iowa and the southern parts of Illinois, Indiana
and Ohio, is a somewhat severe tax upon belief. It is difficult
to imagine the conditions which should have maintained such a
body of water. This has been so much discussed that I need
not dwell upon it. But even if such a body be supposed, it is
difficult to imagine how the deposition could have been precisely
what we find in the case of the loess. It is futhermore difficult
to account for the presence of the land shells which abound in
it; for if this great flood had the ice-sheet for its northern
border, it is extremely difficult to imagine how it could have
been peopled so widely with the terrestrial mollusks.

The limit of the loess does not appear to be a strictly topo-
graphic one. It is difficult to bring its border into strict accord
with a horizontal plain as required by the lacustrine and marine
phases of the hypothesis, or even into a consistent gradient as
required by the fluvial phase, without an arbitrary warping of
the surface. The spread of the loess in the lower Mississippi
valley is more extensive and reaches greater heights on the east

ORIGIN. OF THEILOESS OF THE MISSISSIPPI VALLEY 799

side than on the west side, so far as present knowledge goes. A
similar fact seems to be true of the Missouri valley. I think
this is generally true, but my observations are not sufficient to
justify its unqualified affirmation as a generalization.

There are other difficulties attending the aqueous theory in
its simple application, but I need not attempt an exhaustive
recitial here as they have received emphasis in the long battle
between the eolian and aqueous hypotheses. The foregoing
will I trust suffice to show that there is abundant occasion to
still cast about for a more satisfactory explanation of the loess
puzzle.

The supplementary hypothesis herewith proposed attempts
to divide the honors between the aqueous and eolian agencies.
It recognizes the tremendous force of the arguments from the
distribution and the constitution of the loess in favor of the
glacio- fluvial hypothesis, and it adopts that hypothesis as
the fundamental explanation of the origin of the Mississippian
loess. It assumes the presence of the Iowan ice at the chief
stage of loess deposition. It assumes a very low slope of the
land and a consequent wide wandering of the glacial waters. It
assumes the development of extensive flats over which the silts
derived from glacial grinding were spread. It assumes that the
glacial waters were subject to great fluctuations; 1° as the result
of periods of warm weather in the melting season,and 2° as the
result of warm rains, which not only added directly to the
volume of water, but forced the rapid melting of the ice. Gil-
bert has acutely observed that there is no way in which the
atmosphere can convey its heat energy to a glacier so effectually
as through warm rains.

Let it be imagined, therefore, that the silty waters from the
margin of the ice-fields wandered over broad flats and constantly
built them up by their sediments, and that at periodical flood
stages they extended themselves widely over the plains, while
between the flood stages they withdrew to more limited courses.

The territory covered by the maximum extension of the
waters would be the zone of accumulation of fluvial loess. It is

800 HE (Os (Cla ANNES EISILI ONY.

not necessary to suppose that the periodic extensions of the floods
were destructive of the vegetation over all the flat region. In
some portions not only could vegetation persist, but the land
mollusks and other animals dependent upon the vegetation could
find a temporary retreat from the flood on the taller vegetation
that may have prevailed.

After each of the periodical retreats of the water there
would be left extensive silt-covered tracts facily exposed to the
sweepings of the wind and from these, when dried, dust could be
derived in great quantities to be borne away over the adjoining
lands and lodged in their vegetation. The material thus
derived would be essentially identical with the glacio-fluvial
deposition, and thus the hypothesis seeks to account for the
glacial element in the constitution of the eolian portion of the
loess. The presence of land mollusks in the upland eolian loess
finds in this way a ready explanation, while their presence in the
lowland loess mingled with aqueous mollusks finds an almost
equally obvious elucidation ; for not only would the upland shells
be washed into the lowlands, as we observe they are at the
present time, but they would periodically invade the lowlands in
the intervals between submergence and would be caught and
buried there. Occasionally the shells of the lowland and aqueous
mollusks would be borne to the uplands by organic agencies,
and possibly in rare instances by the severest type of winds,
and hence their occasional presence there is not remarkable.

To make this a good working hypothesis it would appear
that there must be an accommodation between the breadth and
fluctuations of the fluvial deposits and the extent and massiveness
of the eolian deposits, for if we suppose the glacial floods to be
confined within narrow channels, the sweeping ground of the
winds would have been too scant to give origin to the great
mantle of silt then attributable to them, for we must remember
that in proportion as the river work is narrowed the wind work
is expanded. It is obvious that the eolian factor will cut away
its own ground if pushed too far.

There is little question that loess-like accumulations are now

ORIGIN OF THE LOESS OF THE MISSISSIPPI VALLEY 801

taking place on the bluffs adjacent to the Mississippi and Mis-
souri valleys. Observation seems to clearly indicate this. But
such accumulations are relatively scant in amount and limited in
extent, and it is difficult, if not impossible, to believe that the
great loess mantle had its origin from the wind drift of flood
plains no more extensive than those of today. It must be con-
stantly borne in mind that the eolian deposits are measured, not
by the quantity of silt borne by the winds and lodged on the
surface, but by the difference between such lodgment and the
erosion of the surface. Under most conditions with which we
are familiar the erosion is more than a match for the dust
accumulations. The conditions must then have been extraor-
dinary which would give a dust deposition sufficient to supply
erosion and still leave so large a residuum as the loess mantle
implies. The unleached and relatively unweathered nature of
the body of the loess is specially in point here. These con-
siderations warn us of the theoretical danger of too greatly cir-
cumscribing the fluvial action.

On the other hand, if we attempt to extend the fluvial
hypothesis too greatly we fail to leave sufficient feeding ground
for the molluscan life and we encounter the topographical and
physical difficulties which have been previously urged against
the pure aqueous theory. A Janus-faced hypothesis is here
offered in the hope that by a judicious reference of a part of the
loess to one class of action and a part to the other, a joint
explanation may be found to afford a true elucidation of the
perplexing formation. At any rate, it has seemed worth while
to propose the hypothesis for trial. It will doubtless be
extremely difficult to find a line of demarkation between the two
classes of deposits. Such attempts as have been made in this
line justify this apprehension. This supplementary theory has
been in mind for several years and was briefly suggested in my
paper on the Genetic Classification of the Pleistocene Deposits, pre-
sented at the Fifth Session of the International Congress of
Geologists at Washington in 1891." An effort has been made

x Compte-Rendu of the Fifth Session of the International Congress of Geologists,
Washington, 1891, p. 192.

802 We, (C, (CSaVAN ML ILILION

by some of my colleagues and by myself to find criteria of dis-
crimination between aqueous and eolian loess. While individual
types of both deposits are not difficult to find, a criterion or a
series of criteria of general applicability which shall distinguish
the two and assign to each its appropriate part is yet wanting.

Richtofen in his classic work on China urged as the explana-
tion of the great Chinese loess an eolian hypothesis supple-
mented by a fluvio-lacustrine hypothesis. He insisted that the
original and chief loess deposits were formed by dust blown
from the great arid plateaus and lodged on the more fertile plains
of China, and that from these primary deposits the streams
gathered and subsequently redeposited in fluvial or lacustrine
form a subordinate portion, thus giving origin to a secondary
loess formation. Going beyond that field he and his supporters
have apparently tried to apply this secondary factor to the
explanation of difficulties in the European and American loess,
to which its application is more than doubtful. It is interesting,
however, to note that the loess puzzle of China, even in the mind
of its chief exponent, finds a full solution only in a combination
of eolian and aqueous hypotheses. The present writer herein
urges the trial of a similar combination of hypotheses, but
reverses the order of the terms in their Mississippian applica-
tion. The aqueous loess is made primitive and the eolian loess
secondary. The Richtofen loess may be said to be first eolian
and secondarily aqueous; the Mississippian loess, first aqueous,
and secondarily eolian. The Richtofen loess in its ultimate
origin is residuary. The Mississippian loess, in its ultimate
origin, is glacial. The Richtofen mode of origin may be said
to be eolio-fluvial, the mode herein advocated, fluvio-eolian, in
which terms the order of the words indicates the order of deri-
vation and each word signifies a variety of loess.

T. C. CHAMBERLIN.

CieverOpisSCus, FALE.

IN a recent paper in this JourNAL,’ I figured and described
some peculiar disk-like fossils from the Niagara limestone at
Joliet, Ill., identifying them with Hall’s genus Cryftodiscus, and
interpreting them as the possible casts of the gastric cavities of
Meduse. At the time these descriptions were written a part of
the material had been in my hands for two years or more. As
the paper was going to press, too late for revision, additional
material which suggested an entirely different interpretation,
came into my hands from the collection of Mr. E. E. Teller, of
Milwaukee, Wis. These new specimens are from the dolomitic
Niagara limestone of Racine, Wis., and like the others are casts,
the actual substance of the fossil being dissolved out. This new
material shows that the disk-like bodies are not the complete
fossils, but that they are attached to the summit of a tube com-
posed of regularly arranged plates.

The disk portion of the fossil, to which Hall gave the name
Cryptodiscus, was fully described in my former paper. It consists
of an expanded disk with a variously lobed periphery, composed
of four equal plates which occupy the position of the four quad-
rants of the disk. Figure 1, Plate A, and Fig. 6, Plate B repre-
sent the impressions of the lower and upper sides of a very com-
plete specimen from Racine. It is similar to the specimen to
which the name Cryftodiscus digitatus was given in my former
paper, but differs from that species in the lobing of the periph-
ery. If broken off at the bottoms of the lobes it would have
the contour of C. kydet. The lower side of the disk with its
central funnel-shaped depression with the central elevation is
not different from those formerly described, but the upper side
of the specimen is more nearly perfect than any of those. It is

™“ On the Presence of Problematic Fossil Medusz in the Niagara Limestone of

Northern Illinois.”—Jour. GEOL., Vol. V, p. 744.
803

804 STUART WEELER

flat across the central portion with the exception of a small
_ square fractured area in the exact center. This fractured por-
tion corresponds to a similar fractured area at the summit of the
central prominence of the lower side, and really represents a
perforation through the disk in its perfect condition.

The impression of the upper side of the disk of another
species is seenin Fig. 4, Plate A. The lobing of the periph-
ery is different in this species, but its greatest peculiarity is in
the presence of the impressions of four rather slender diverging
spines, one on each quadrant, surrounding the fracture represent-
ing the central perforation of the disk.

In the limestone at Racine, associated with Cryptodiscus, the
internal casts of some peculiar tubelike bodies have been found
by Mr. Teller. Two views of the most perfect of these specti-
menspare) Shown on later Eige 3.sand later a). ice /emmeeabe
tubes are composed of plates arranged in ranges of four each,
and in the specimen illustrated the impressions of three such
ranges are preserved. The top range consists of two longer
plates and two shorter ones; the middle range consists of two
plates. below the shorter plates of the top range, which are placed
higher than the two plates below the longer plates of the top.
The lower ends of the basal range of plates are not preserved,
but the summits are alternately higher and lower, to correspond
with the plates of the middle range.

The specimen which forms the connecting link between the
disk and the tube 1s illustrated on) Elate sas wince: 25. lnsthis
specimen the disk and the tube are both incomplete, but the
relative position of the two is perfectly shown. The four quad-
rants of the disk are shown to be but the greatly expanded
margins of the four plates in the top range of the tube, and the
central elevation seen in the impressions of the lower side of the
disk, is the summit of the internal cast of the tube.

When the relationship of the disk to the tube was recognized,
the crinoidal character of Cryptodiscus could not be questioned ;
and a comparison of the arrangement of the plates in the tube
with the arrangement of the plates in the dome of Calli crinus,

CRYPTFODISCUS, TALL 805

Stuart Weller del

PLATE A

806 STUART WELLER

Sys ZN
: VS =

Staard Weller, adel.

PLATE Bb

CRAP TODISCUS, HAHL 807

showed Cryptodiscus to be but a portion of the dome of mem-
bers of that genus.

Figure 9, Plate B, isa diagram adapted from Wachsmuth and
Springer, to show the arrangement of the plates in the calyx of
Callicrinus costatus His., the type of the genus. The dome is
composed of four ranges of plates, of which the first contains
ten, and the second, third, and fourth ranges, four plates each.

Figure 8, Plate B, shows diagramatically the arrangement of
the plates in the Racine specimen. The three ranges of plates
present in these specimens correspond to the second, third, and
fourth ranges in the dome of C. costatus. The plates in the
Racine specimens differ from those of C. costatus in the third
range; the two lower plates of this range are not in contact lat-
erally, as in that species, but are separated by the downward
extension of the two upper plates, which meet the truncated
upper ends of the two corresponding plates of the second range.
The most conspicuous difference between the Racine specimens
and C. costatus, is in the greatly expanded margins of the plates
of the fourth range, forming the disk to which the name Cryféo-
discus has been applied.

Figure 5, Plate A, which shows the external impression of a
portion of a disk attached to the tube, is introduced to show
a peculiar ring-like canal which surrounds the tube just below
its junction with the disk. This canal is open entirely around
the tube so far as it is preserved, and a pliable wire inserted at
one side passes around and out on the opposite side. On the
impression itself, just above the angle between the disk and the
tube, is a series of small slit-like openings which apparently
connect with the ring canal. In the actual specimens, of course,
these openings were represented by a solid ring around the tube,
which was supported by a series of small bars connected with
the basal portion of the under side of the disk. No explanation
of these characters can be offered.

In their monograph, ‘“‘The North American Crinoidea Cam-
erata,’’ Wachsmuth and Springer recognize from the dorsal cups
alone, four species of Cadlicrinus—C. beachleri from St. Paul,

808 STUART WELLER

Ind., C. acanthus from Lockport, N. Y., C. cornutus from Racine,
Wis., and Chicago, Ill., and C. vamifer from Tennessee. From
the St. Paul beds in which C. deachlert occurs, Miller* has figured
a specimen of Crypfodiscus. From the Racine beds, associated
with C. cornutus the specimens illustrated in this paper were
obtained. From Lockport, N. Y., and from Tennessee there is
as yet no record of Cryptodiscus, but specimens may yet be found
in these localities. The known localities for Cryptodiscus are
Racine; Wis., Joliet, lily est. Raul ind: and jones; county,elas
and in all these, with the exception of the last, the dorsal cups
of Callicrinus are found associated with it.

The correlation of Cryptodiscus as a genus with Callicrinus
seems complete, but material has not yet been found by means
of which the species of Cryptodiscus may be correlated with the
species of Callicrinus described from the dorsal cup.

The genus Cryptodiscus, founded by Hall, was never properly
described, nor were the relationships of the fossils to which the
name was applied, properly understood. D’Orbigny’s name,
Callicrinus, also has priority over Hall’s, so it becomes necessary
to drop Cryptodiscus entirely, and to refer all the specimens to
Callicrinus. The different forms of disks doubtless represent
distinct species of the genus, but there may be a difference of
opinion as to whether species should be established upon the disk
alone without a knowledge of the dorsal cup, and no names will
be given to the Racine specimens for the present.

STUART WELLER.
THE UNIVERSITY OF CHICAGO.

*Eighteenth Rep. Dep. Geol. and Nat. Rec., Indiana, p. 260, Pl. I, Fig. 7.

A NOTE ON TEE MIGRATION OF DIVIDES:

SAN CLEMENTE ISLAND, one of a group lying off the southern
coast of California, is a typical orogenic block,? formed by fault-
ing in geologically recent times. Its drainage is still in its
infancy, and is therefore very simple. A study of the topo-
graphical features of this isolated mass has led the writer to
consider the effect on a previously established drainage system,
of faulting with consequent migration of divides.

In the case of San Clemente, as the slope toward the line of
faulting is by far the steeper, erosion on that side is much more
rapid, and. consequently the main watershed of the unmodified
crust-block migrates away from that side toward the other. In
this case then, the movement of the divide is from the line
along which the elevation takes place—that is, from the line of
faulting. This differs from an uplift along an axis, without
faulting, in a topographically simple region of homogeneous
rocks, as in the latter case the axis of uplift itself forms the
ultimate divide, while in the former case the resulting divide is
situated at some distance to one side of the line of faulting.
Thus the effect on a simple drainage system already established
will be different for the two kinds of crustal movements, and the
law for the migration of divides as given by Campbell? must be
modified in order to make it applicable to an uplift accompanied
by pronounced faulting.

This may be illustrated as follows, assuming, as Campbell
has done, the simplest possible conditions, in order to eliminate
disturbing elements from the problem: In Figs. 1, 2 and 3,
C represents the divide between the symmetrical drainage slopes

«Published by permission of the Director of the United States Geological
Survey.

2 Bull. Dept. Geol. Univ. Cal., Vol. I, No. 4, p. 129.

3 Jour. Geol. Vol. IV, No. 5, July-August 1896, p. 580.
809

810 WM. SIDNEY TANGIER SMITH

of the two stream profiles, CBA and CDE. If faulting
occurs parallel to this divide, with a downthrow toward the left,
it may occur on either side of C (leaving out of the question
the possible occurrence of a fault at C itself). Suppose, first,
that the fault is to the left of C, at B (Fig. 1), and that the

B! Ct
3 Gi D’
A B Zp
ee Cc Ec
B’ D
Fic. 1.

faulted portions have assumed the positions indicated by B” C’
D’ Eand AB’, A and E representing the limits of movement
in either direction.t The part B C will have had its angle of
slope decreased by elevation, and therefore the rate of erosion
on this slope will be diminished. The angle of the slope CDE,
however, will have been increased, and its rate of erosion will be
correspondingly greater. The slope C’D’E, then, will be cut
away more rapidly than the opposite slope, C’B", and the divide,
C’, will migrate toward Bis in, accordance with) the mormnal
operation of the law. This condition, however, will last only a
comparatively short time, for on account of the high angle of
BB’ erosion on this slope will be very vigorous, and the point
B" will be rapidly carried back toward C’, till the two meet.
When this stage is reached the edge of the faulted block will be
represented by C", and the profile, approximately, by B’C'E.
Further erosion will tend to carry the crest C" toward E, owing
to the more rapid cutting on the steeper slope, B’ C’. The
final result will be that the point C” is carried to some point
such as D’, the exact position of which depends on the relative
attitude of the points which correspond to B’ and E, when
erosion has reached this stage.
The second case (Fig. 2), when the faulting is between the
« These sections are diagrammatic, and do not attempt to give the exact relative

positions of the two parts, as these positions depend on the circumstances obtaining
at the time of faulting.

A NOTE .ON THE MIGRATION OF DIVIDES Sil

divide, C, and the point E, is similar to the last in the movement
of the crest of the faulted block toward D, or away from the line
of faulting. In the former case, however, the initial movement
(for the fault-block) was toward the fault-line, while in this case
that feature is eliminated, as the faulted portion D" E excludes

iG. 2:

the original divide C. In this second case, this movement of
the crest of the block D’ D" E is thus away from the divide, C,
also, and the final result of the uplift is the establishment of a
divide for the crust-block, at some point betwen D’ and E,
depending on the relative attitude of these two points.

If the faulting has been sufficient this resultant divide will
form the main watershed for the region, the original divide, C
being now of insignificant proportions. The faulting may,
however, be such that the portion ABCD cannot be left out of
account. If, as shown in Fig. 2, the final position of ABC D is
more elevated than its original position, the slope CD will have
been decreased, while ABC will have been slightly increased.
As a consequence there will be a migration of C’ toward D’.
If the faulting is sufficient in amount, the migrating crest will
finally reach D’, and there will be no divide other than that of
the faulted block, D’ D” E. As the movement of the crest-line
in this case is toward E for the parts on both sides of the fault-
line, the resultant crest must be at some point between C’ and E,
whether the amount of faulting be great or small.

If, on the other hand, the movement of ABCD is one of
depression (Fig. 3), the result is more complicated, and the
final position of the crest C’ will depend on the relative attitudes
of the faulted portions AB’ C’ D’ and D’ D" E._In other words,
if the sum total of movement in the two parts produces eleva-
tion, the migration of the divide will be in the direction of E,

812 WM. SIDNEY TANGIER SMITH

while if the resultant of the movement is a depression the divide
will migrate toward A.

If the faulted block D’ D” E were elevated from submarine
depths to a position similar to that of San Clemente, the final

Dp"
:
A B y. E
; Cano;
FIG. 3.

result of erosion would be a divide midway between the limiting
waters on the two sides.

The results here arrived at must be true in all cases, whether
the movements causing faulting are slow or rapid, continuous or
intermittent in their action, and small or great in amount. Varia-
tion in these factors, however, will cause a variation in the rate of
the migration, or in its extent. Other modifying factors are the
relative positions of the divide and the line of faulting, and the
dip of the fault-plane.

To sum up: Where simple crustal movements occur, causing
faulting with resultant elevation, a migration of the stream divide
will follow, in the direction of the line of faulting when the fault-
scarp faces the divide, away from the line of faulting when it
does not. Or, in other words, the migration is from the axis of
faulting when the faulted block includes the divide, and toward
the axis of faulting when it does not.

Wy. SIDNEY TANGIER SMITH.

DISCOVERY OF MARINE JURASSIC ROCKS IN
SOUTHWESTERN. TEXAS.

SEVERAL announcements of marine Jurassic rocks in New
Mexico and Texas have been made by authors, the earliest as
also the latest by Mr. Jules Marcou; but the marine sediments
hitherto called Jurassic in these states belong to the Comanche
series. Modtola jurafacies, Homomya jurafacies, Exogyra hilh, and
possibly one or two other members of the fauna of the latter
series, which are more or less clearly analogous with fossils of
the European Jurassic, should doubtless be regarded as survivals
from a preceding age. Such survivals are only to be expected,
and these therefore do not contradict the results arrived at by
Professor R. T. Hilland Mr. F. H. Knowlton, who have shown that
the lowest formation of the Comanche series presents a Wealden
fauna and flora. The data of old-world stratigraphy seem to
show that the Wealden formation is part of the Cretaceous system,
or, more definitely, is the estuarine and arenaceous extension of
lower Neocomian sediments that are elsewhere of purely marine
origin and largely calcareous.

It is a principle recognized by many geologists that where
the conditions afford only paleontological data for correlation
and these data show a commingling of fossils of two successive
systems, we should not suppose that the latest occurrence of
fossils of the earlier system characterizes the highest rocks of
that system, but should assume that the first appearance of a
fauna essentially characteristic of a later system, whether it be accom-
pamed by survivals from an older fauna or not, marks the beginning
of a new rock-system and age. By this criterion Professor C. S.
Prosser of the United States Geological Survey has recently drawn
the line separating the Permian system from the Carboniferous in
the Plains region; and in ‘accordance with the same principle,

if the prevalent European acceptation of the Cretaceous system
813

814 eV a GCA GHUNG

be adopted for America, the entire Comanche series belongs to
the Cretaceous.

No true Jurassic of marine origin, therefore, has hitherto
been recognized in the southern part of the United States."

In 1893, when studying the Cretaceous fauna of Texas, as
represented in the museum of the Geological Survey of that
state, I was led to suspect the occurrence of Jurassic rocks in
the vicinity of Malone, a flag-station of the Southern Pacific
railway between El] Paso and Sierra Blanca Junction. The
evidence of such possible Jurassic formation was derived from
the study of a small collection of Mesozoic fossils that had been
obtained by Messrs. W. H. von Streeruwitzand Ralph Wyschetzki,
according to the field-labels, ‘‘in hills about a mile northeast of
Malone.”’ The collection, though small, revealed a fauna quite
different from any known in the North American Cretaceous,
and one which, it was therefore surmised, might be pre-Comanche.
All of the material that was deemed sufficient for study was
treated of in the writer’s ‘Contribution to the Invertebrate Pale-
ontology of the Texas Cretaceous,” in the Fourth Annual Report
of the Texas State Geological Survey. It included six species, all
apparently new to science, which were described under the
following names: Anatina tosta, Cucullea transpecosensis, Cyprina
(? Roudairia) streeruvitsi, Trigonia vyschetzki, T. taffi, and Venus
matonensis. These fossils threw little light on the question of
Jurassic or Cretaceous age of the rocks in which they occurred,
as all of the genera were known to be common to both of these
geological systems, and the two species of Trigonia were regarded
as presenting features that allied them to both certain Jurassic
and certain Cretaceous trigonias. The problem was therefore
left unsolved.

Besides the Malone hills, the only locality where any fossil

*The Morrison Formation (Cross) of Colorado and Wyoming was traced along
the front of the Rockies many years ago by Dr. F. V. Hayden at least as far south as
Las Vegas, and its occurrence at the latter point has been recently confirmed by
Professor Alpheus Hyatt. But this, though it has usually been called Jurassic, is now

beginning to be regarded by some as probably lower Cretaceous (Wealden), and,
whatever its age, is a fresh-water formation.

MARINE JURASSIC ROCKS IN SOUTHWESTERN TEXAS 815

purporting to belong to the same fauna had been collected was
Bluff mesa, upon which Mr. J. A. Taff of the Texas Survey had
obtained part of the type-material of 77zgonia taffi, the remainder
being labeled as from the Malone locality. The rocks of Bluff
mesa having been referred by Mr. Taff to the ‘‘ Washita division”
(though the fossils he named from them were Glen Rose species)
there was literary evidence that seemed to connect the Malone
fossils with the Comanche series. Awaiting further light, they
were therefore left among the fossils of that series. The
‘“Washita”’ intended by Mr. Taff included both the true Washita,
as originally established by Dr. B. F. Shumard under the name,
Washita limestone, and the Denison formation of Professor Hill.

I did not, however, feel satisfied with this disposal of them,
and | determined to reéxamine the matter at the earliest oppor-
tunity. This came in a journey made to Guaymas, Mexico, in
the spring of 1895, by my friend, Mr. Robert W. Goodell, who,
at my request, and assisted by his father, Mr. R. R. Goodell,
very kindly made a side trip to the Sierra Blanca Mountains
and the Malone hills to obtain further collections and data from
those localities. From the Sierra Blanca Mountains, one of the
localities of Comanche rocks nearest to the Malone hills, the
Messrs. Goodell brought back many species of Mesozoic fossils,
all of them apparently from Comanche rocks, most of them
Washita forms, and many of them profusely abundant, but
not one of them identical with fossils of the Malone hills.
The Goodell collections from the Sierra Blanca Mountains and
the Malone hills not only emphasized the distinctness of the
fauna of the latter locality from that of the Comanche series,
but they also settled the age of the Malone fauna. For, from
the Malone hills they included, besides three of the species
collected there by earlier explorers, several other forms, all of
which seemed to be new to science,? and one of which was a

*Second Annual Report of the Geological Survey of Texas, pp. 719, et seq., and
Plate XX VII.

?Since this was written, two of these forms have been found to be probably
identical with two fossils that have been described from the Jurassic of Mexico. See
footnote relating to Pleuromya and Lucina.

816 FF. W. CRAGIN

Trigonia of the section, Undulat@, a type exclusively character-
istic of Jurassic rocks. This beautifully ornamented shell is of
medium or smaller than medium size in the genus, ovate, strongly
inflated, and has the partly continuous and partly tuberculated
ribs abruptly angulated. I have named it, after Mr. Robert W.
Goodell, Trigonia goodellt. Moreover, a careful reéxamina-
tion of Trigonta vyschetzki, made possible by the new material
in the Goodell collection, indicated that it belonged to the
Clavellaté section of its genus, asection chiefly of Jurassic occur-
rence. As Trigonia is, among lamellibranchs, relatively important
as a means of stratigraphic diagnosis, and as none of the Malone
fossils agreed with species known in the lower Comanche, the
evidence from the Goodell collection has led me to refer the
Malone fauna and formation to the Jurassic system.

The vicinity of Malone was visited but once by the Messrs.
Goodell (March 30, 1895), and then for only part of a day,
their journey thither having been made from Sierra Blanca by
wagon.

Iam indebted tothe kindness of Mr. Robert W. Goodell for the
use of his field notes on the Sierra Blanca region, and partic-
ularly for those on the Malone hills, which include a section
across the latter at a point considerably west of that at which
Mr. R. R. Goodell collected the fossils and presenting different
but apparently related conditions. His Malone hills notes are
as follows:

A careful search of the western end of the line of hills one mile N. E. of
Malone failed to reveal any fossils. The following is a section across the
western end of this line of hills.

Bearing [magnetic] of line from station to beginning of section-line,
INS FO? 13,

Bearing [magnetic] of section-line, N. 20° E.; one-half mile from station.
[ Malone station. |

1) 340 feet heavily bedded limestone ; no fossils; seams of calcite abun-
dant; dip ; labeled M.

2) 30 feet coarse gypsum; dip 75° S. 40° W.; labeled N.

3) 10 feet laminated gypsum; dip 75° S. 40° to 50° W.; labeled O.

4) 50 feet red grits interspersed with seams of gypsum of various widths ;
dip 75° S. 40° to 50° W..; labeled P.

MARINE JURASSIC ROCKS IN SOUTHWESTERN TEXAS 817

5) 110 feet coarse gypsum, same as N.

6) 450 feet heavily bedded limestone, with many seams of calcite which
in places are several feet wide. That is, there are places several feet wide
where there is more calcite than limestone. Dip hard to get, but at one
place halfway across the bed it was 75° N. 40° E.; labeled Q.

General direction of hills nearly E. and W. The water has worn out a
little draw in the gypsum beds between the limestone.

Several hundred yards west of where this section was made, at the extreme
N. W. end of these hills, near the R. R., is an outcrop of soft sandstone.
Parties have opened this up in one or two places, in search of fossils perhaps,
but I could find no trace of any.

About a mile east of where I made this section, between the last two hills
of this series, R. R. Goodell found an outcrop carrying fossils; a large clam,
a Trigonia with rough nodular ridges, and two other bivalves. Outcrop 500
feet long, 150 feet wide; strike N. and S.; dip about 20°E.

Instead of four species of bivalves, however, the collection
which the Messrs. Goodell brought back from this locality
included seven, besides a fragment of an eighth and one of an
ammonite. The bivalves included Pholadomya tosta (which the
Goodell collection showed had been erroneously referred to the
genus, Anatina); Trigonta vyschetzki; the new Trigonia of the
Jurassic section Undulate, T. goodellit; a subcircular, strongly
compressed shell which is either a Cyprimeria or a Lucina, and
to which I have given the MS. specific name metrica, from its
being ornamented with concentric, sharply raised lines disposed
at ample and remarkably regular intervals; a plain or gently
and irregularly concentric-undulate, elongate Plewromya—P.
malonensis of my MS.,' showing in several examples the over-
lapping of the left hinge-margin by the right, characteristic of
this genus; the Venus malonensis; an indeterminate ostreid
(shown only in section, imbedded) ; and a fragment of another
shell, possibly a 7rigonta of the section, Costate. The Pleuromya
bears more or less resemblance to P. henselt Hill, a Glen Rose
species which the writer has collected at a number of localities

«Since this and the preceding species were studied, drawn, and named, I have
recovered a mislaid copy of Castillo and Aguilera’s ‘‘Fuana Fosil de la Sierra de
Catorce ” (Boletin de la Comision Geologica de Mexico, Num. 1), and it seems to me
that there can be little doubt of their belonging respectively to the Plewromya inconstans
and Lzcina potosina of those authors.

818 Ff. W. CRAGIN

in north-central Texas and which is especially abundant in
Hamilton county of that state. Specimens of both species, as
usually preserved, vary somewhat in shape owing to mechanical
distortion, and it is difficult to determine their precise natural
form. Apparently, however, the Malone species differs from
the P. henseft in having its posterior portion less tapering and a
little recurved. The ammonite fragment did not show the
suture; but the form and ribbing indicate a type common in the
upper Jurassic.

As shown by the the rock adhering to fossils in the Goodell
collection, the fossiliferous strata of the Malone hills consist in
part of hard yellowish to brownish gray calcareous sandstone or
arenaceous limestone. The sandy component is largely the
débris of acidic eruptive rocks of undetermined varieties. But
it seems probable that the massive, calcite-seamed limestone and
the gypsum occurring in the more westerly part of the same
hills and across which Mr. Robert W. Goodell’s section was
taken, are closely associated and should be referred to the same
formation with them ; and ifso the similar gypsums and massive
limestones of Malone Mountain, described by Mr. Taff as the
Malone formation (which in several respects the Goodell section
duplicates), is a prominent part of that formation. For the
formation, therefore, provisionally regarded as embracing the
fossiliferous sandstones and limestones, the gypsums, the massive
calcite-seamed limestones, and any other rocks included among
these, of the Malone Mountain and the hills north and east of
Malone Station, Mr. Taff’s name Walone beds, or Malone for-
mation is appropriately retained. The Malone formation thus
assumes wider limits, a different age-significance, and far greater
importance than were assigned to it by Mr. Taff. Yet to him
belongs the credit of having published the first section from it,
and of having called attention to the fact that the Malone uplift
is older than other orographic features of the Sierra Blanca dis-
trict

The Geological Map of Mexico, published by the late Direc-
tor of the Geological Survey of Mexico, Sefior Castillo, shows a

MARINE JURASSIC ROCKS IN SOUTHWESTERN TEXAS 819

limited area of Jurassic rocks in northern Mexico, not far south-
west of Saltillo. This is apparently the nearest known occur-
rence of marine Jurassic rocks to that here announced, being dis-
tant from Malone some 500 miles in a southeasterly direction.
The discovery of Jurassic rocks in El] Paso county, Texas, there-
fore, raises the interesting question whether other limited areas of
Jurassic may not yet be discovered in intermediate territory.

This article in major part, including definite reference of the
fossiliferous beds of the Malone hills to the Jurassic upon evi-
dence derived from the Trigonias of the Goodell collection, was
first written in the latter part of 1896. Its publication was post-
poned, — with some revision of the manuscript in the meantime,
—in the hope that I might soon visit the formation in person
and secure more abundant data. This I was unable to do till
August last. Reaching the vicinity on the nineteenth of the
month, I spent about three weeks exploring some of the locali-
ties accessible from Sierra Blanca station, devoting principal
attention to the Malone fauna and formation. The large col-
lection of fossils made from the latter, so far as yet studied, con-
firms the reference to the Jurassic. I at first intended to incor-
porate the results of this trip with those derived from the Texas
Survey and Goodell collections and data ; but it has seemed best
to publish deductions from the earlier data without the further
delay involved in the study of this season’s material, and to pre-
sent the results of the latter study, when completed, in separate
articles.

When this article was first written, I did not have access to
the first number of the Boletin de la Comision Geologica de
Mexico, containing Castillo and Aguilera’s ‘‘ Fauna Fosil de la

”)

Sierra de Catorce,’’ my copy of it having been temporarily lost
in the exigencies of a change of residence. The missing docu-
ment has since come to light, and the independent reference
which I have made of the Malone fauna to the Jurassic, is con-
firmed by it, Plewromya inconstans and Lucina potosina being appar-
ently common to the Malone and the Alamitos (‘upper

Jurassic”) formations (as elsewhere indicated in footnotes), and

820 F. W. CRAGIN

the ornamentation of the Malone ammonite fragment apparently
agreeing with that of the Alamitos form, Hfoplites bifurcatus.

In conclusion, I regret to have to record the recent decease
of Mr. Robert W. Goodell, which occurred at his home in
Houghton, Michigan, on the 23d of September last, and in his
28th year. I regard his early calling away, not only as a personal
bereavement, but as a distinct loss to science as well; for, though
an invalid, and unable to bear the confinement involved in the
elaboration of his out of door observations, he was a young man
of unusual intellectual ability and promise and an enthusiastic
and careful observer. He had done considerable field work on
the Laramie, Denver, and Fort Union formations in the area
between Denver and Colorado Springs, and on several other mat-
ters of Colorado, Texas and Michigan geology; and, as appears
in the present article, it is to his zealas a scientific explorer that
we owe the trip to Malone which, aided by his father’s more
robust physical strength, resulted in the means for the first satis-
factory diagnosis of the age of the Malone hills fauna; and
in an important advance in our knowledge of the distribution

of North American Jurassic rocks.
F. W. Crain.

COLORADO SPRINGS, COL.

ANDENDIORITE IN JAPAN.

In the northern fringe of the Kwanto plain, the environs of
Tokyo, there is a series of volcanoes, including Asama, Haruna,
Akaki, Niko, and Nasu, some of which are active, while the
others are totally extinct. One of the oldest rocks erupted from
these volcanoes is exposed at Usui Pass, in the form of propy-
lite. The pass makes several trends along the steep, rocky
slope of propylite mountains, and the railway of the Abt system
passes through the rock by means of twenty-six tunnels. The
propylite directly overlies the Miocene beds.

The propylite seems to have been derived from augite-ande-
site ; the normal variety has a homogeneous aspect, looking like
a common andesite. The usual forms are altered. They are
white or pale greenish, with scattered granular or sometimes
cubical crystals of pyrite. Yellowish epidote grains and calcite
crystals are also distinctly observed.

Midway between the telegraphic posts No. 367 and No. 368,
on the same pass, I have seen, piercing through the above men-
tioned propylite, an interesting diorite dike, extending in an east
and west direction. The eastern part of the dike is coarse-crystal-
line, while the other end is fine-granular or somewhat porphyritic.

The diorite, which is manifestly younger than the Miocene
beds, is a hypidiomorphic aggregate of plagioclase and horn-
blende, with quartz, magnetite, iron pyrite, and remains of
augite, sometimes mixed with hornblende. Epidote and chlorite,
besides secondary pyrite, are also very common as secondary
products. The plagioclase is distinguished with the naked eye
as milky white grains, while the hornblende is greenish black,
with a resinous luster on the newly cleaved surfaces. Iron
pyrite and epidote grains are always found on the fresh surface
of the rock, with their characteristic colors.

The plagioclase, which is the most important essential
821

822 C. IWASAKI

ingredient in the rock, under the microscope is somewhat clear
and fresh, exhibiting the extinction angle of labradorite. The
albite type is the most common among twins, and the pericline
type, also, is frequently found in the same individuals. Zonal
structure, with different optical orientation, is often met with.
Sometimes the core exhibits an eight-sided section, while the
outline of the whole crystal is nearly rectangular. The crystal
is often partly idiomorphic and partly allotriomorphic. It
usually contains glass enclosures, which are seldom zonally
arranged. Sometimes immovable gas bubbles are seen. The
presence of liquid enclosures is very uncertain. The feldspar is
generally fresh and clear. Decomposition begins at the cracks,
where epidote grains are produced. In some cases they entirely
replace the feldspar.

Next to the feldspar, the most abundant mineral is horn-
blende, either fibrous or compact, which fills up the interspaces
between feldspar crystals. The characteristic cleavage along
(110) is very distinct. The prevailing color is green, with the
following pleochroism: g = greenish brown, b = brownish green,
¢— green. The extinction angle 1s) about) 12;) but, the decome
posing individuals exhibit an undulatory extinction. Many of
the hornblende crystals are derived from augite. The sections of
the latter are brownish in color, with a greenish tinge, compact
in texture, with their characteristic cleavage and an extinction
angle of about 38°. Sometimes such a compact augite is con-
verted into one with granular texture, each of the grains retain-
ing the optical property of augite. The granular augite is con-
verted into fibrous hornblende. These fibers are generally
united in bundles, parallel to each other. The vertical and ortho-
axes of the primary augite and of the secondary hornblende
are nearly always in parallel position, sometimes forming a
pseudomorph of hornblende after augite, which is distinctly
seen in cross section. The green fibrous hornblende is further
decomposed into epidote grains or chlorite. Occasionally all
these stages of alteration may be seen in one section, surround-
ing each other in regular order.

ANDENDIORITE IN JAPAN 823

Quartz which is surely primary is totally allotriomorphic, and
fills up the interspaces between feldspar crystals. It is always
fresh, contains glass enclosures, and sometimes well-shaped
crystals of pyrite.

Magnetite is very common. An opaque ore,’perhaps ilmenite,
undergoes decomposition in such a manner as to leave more
resisting lamella cutting each other at 60°. The pyrite con-
tained in quartz is certainly of primary orgin.

Notwithstanding the holocrystalline structure of the rock,
there are, occasionally, remnants of groundmass, which consist
of microscopical grains of plagioclase, hornblende and iron ores.
In a fine granular, porphyritic variety of the diorite, phenocrysts
of feldspar are scattered in the aggregate of smaller lath-shaped
feldspar individuals, which corresponds to the groundmass of the
neovolcanic rocks. The above mentioned facts seem to show
that the diorite is not a normal plutonic rock, but most probably
a sheet or dike, which has solidified in the region of slight
pressure.

Contact metamorphism.— In the neighborhood of the diorite,
the propylite is so highly decomposed that traces of the contact
metamorphism cannot be recognized. Although the Tertiary
beds are never found in contact with the diorite dike, a Tertiary
shale found about 330 feet to the north of the diorite is har-
dened like a hornstone and contains iron pyrite, which is not
usual with the unaltered shale of the region. This change of
shale seems to be due not to the action of the propylite lying
between the diorite dike and the shale but to the diorite itself,
which, in fact, has been taken out from a railway tunnel exca-
vated close to the exposure of the shale. It seems probable
that similar diorite dikes run through the Tertiary beds every-
where beneath the surface, because we frequently find hardened
shale with a contact mineral, whose exact nature has not yet
been ascertained.

Steizner * describes a quartz-bearing mica-diorite of Argen-
tine under the name of ‘‘Andendiorit”’ as a neovolcanic dike

*STELZNER, Geologie u. Palzontologie von Argentina, p. 213.

824 C. IWASAKI

rock in the following words: ‘U. d. M. beobachtete man sehr
deutlich Plagioklas, Quarz und braunen Glimmer; daneben
scheinen auch noch kleinen Menze von Orthoklas und Horn-
blende vorhanden zu sein. Der Plagioklas ist sehr frisch, wasser-
hell, hier und da etwas rissig ; er hat oft zonalen Bau beherbergt,
wieder die oben bereits mehrfach beschriebenen Glasseinschlusse
von der Form negativer Krystalchen mit anhaftenden opaken
K6rnchen, ferner einzelne Flissigkeitseinschlisse, Dampfporen
und farblose, sowie blassgrune Mikrolithen. .... Die Horn-
blende tritt uns vereinzelt auf, und ist bereits durchgangig stark
zersetzt und zerfasert.”’

The diorite at Usui Pass is also a Tertiary eruptive, and closely
resembles Stelzner’s andendiorite in the microscopical properties
of the plagioclase, especially in the zonal structure and the glass
enclosures with attached opaque granules, which are nearly always

absent from the true plutonic diorite.
C. IwasAkI.
KYOTO, JAPAN.

SiUDIES IN THE DRIFTLESS REGION OF
WISCONSIN:

THE superficial deposits of this region, aside from the interest
which would naturally attach to any such deposit, possess a
certain special interest due to the relation the region holds to
the adjoining glaciated territory, and the presumption that they
might furnish a record of certain subsidiary facts which from
the nature of the case the glaciated region itself could not furnish.

The field as a whole is a most inviting one for study, present-
ing as it does considerable variety. But the purpose of this
article is more especially to describe a particular deposit as seen
in the vicinity of Trempealeau on the Mississippi River. As
some knowledge of associated beds is necessary to a full
understanding, I will briefly describe them in order beginning
with:

The loess.— From the upper limits reached by the Champlain
floods, all the smaller valleys, the lower hills, and, in a less degree,
the higher hills are covered by a bed of clay, the average thick-
ness of which may be between twenty and thirty feet, but it

‘Early in 1894 Mr. G. H. Squier brought to the attention of the senior editor of
this JOURNAL some observations which he had made on ridges of coarse gravel and
bowlders in the vicinity of Tomah, Wis., which lies in the heart of the driftless area.
It was his opinion that the formations constituted evidence of local glaciation.
The débris was described as made up of chert and sandstone too coarse to be
easily accounted for, in his opinion, by floods. It formed ridges on the slopes or
side-plains of the valley and neither had the form of definite terraces nor of axial
valley drift. No glacial striation either of the transported rock or of the rock zm site
were observed, nor were glacial contours recognized in the configuration of the valley,
nor distinctively in the ridges of débris. These deficiencies of evidence seemed less
important however than the apparent absence of limestone débris. The deposit in
question seemed to be made up wholly of sandstone, chert, and other residuary
material. As limestone lay on the summit and formed the protecting crown of the
highlands in which the valleys head, and as its habit of outcrop is such that it could
readily yield massive blocks to glaciers occupying the heads of these valleys, and
further, as limestone is habitually present in morainic débris formed in such situations.

825

826 G. H. SQUIER

varies greatly. Two measurements obtained not over ten rods
apart, one on the crest ofa hill, the other on its west slope, gave
seventeen and thirty-two feet, respectively, with indications that
at some intermediate point it may reach fifty feet. It is almost
wholly free from stones and very homogeneous in texture,
though the deeper parts are somewhat lighter in color and more
friable, the result apparently of a large admixture of sand. Save
in the valleys, it usually overlies the residual material derived
from the disintegration of the underlying rocks, or near the foot
of the hills, the talus, which being often nearly pure sand well
shows the abruptness of the transition. In rare cases it rests
directly on the rock.

while it is habitually absent from accumulations formed by weathering and by proc-
esses sequent upon weathering, the balance of evidence seemed to me adverse to the
glacial hypothesis. At any rate, it seemed best to urge more prolonged and critical
study before publication.

In February 1895 Mr. Squier presented similar data more fully worked out
with reference to ridges of bowldery material accumulated about Trempealeau
bluff on the Mississippi, in the northern part of the driftless area. The absence
of limestone cannot be urged here with the same force as at Tomah, since it occurs
in at least one locality. The absence of glacial scratches on the transported rocks
as well as the valley sides, and the lack of specific morainic contours leave much
to be desired here as at Tomah, but these deficiencies are not necessarily fatal
to the glacial hypothesis. The conception of Mr. Squier, that the glaciers were
formed by snowdrifts lodged in the valleys, and not by summit accumulations, is
doubtless the true one if the glacial interpretation be true at all. Examples of such
snowdrift valley glaciers occur in the extra-glacial belt in Greenland, and might
reasonably enough be supposed to have occurred in the driftless area. But if these
deposits are really due to local wind-drift glaciers decisive evidence of the fact should
be forthcoming on a sufficiently prolonged and critical search. A coarse massive
mixture of residuary material, however difficult of satisfactory explanation by other
agencies, cannot safely be taken as in itself proof of glacial origin. It must be
remembered that as a result of the excessive superficial thawing and freezing incident
to glacier-border conditions, the facilities for landslides, bodily creeps, and similar
modes of movement reached an extraordinary degree of development. I have seen
in Montana a modern landslide that imitated a glacier almost perfectly in the deploy-
ment of its material. In Yellowstone Park, Mr. Hague showed me several years ago
an almost perfect imitation of glacial deployment assumed by a talus mass of angular
blocks of igneous rock. When such formations consist of mixtures of earthy and
rocky material, their positive differentiation from glacial deposits may not be always
successfully attained. So long as the constituent material is essentially residuary
in origin, and there is an absence of any notable quantity of unweathered rock

THE DRIFTLESS REGION. OF WISCONSIN 827

Stratified beds.—In the valleys up to about one hundred feet
above the river, the loess usually overlies stratified beds. The
upper surface of the main body of the beds is not as highas given,
but beds of similar character, of no great thickness, persist for
a short but indefinite distance up the hillside. The thickest
section I have seen shows about fifteen feet without exposing the
base. In composition, sand forms by far the most abundant
element, especially in the thickest places. Clay is present how-
ever, in some places interstratified with sand, and stones not
exceeding a few pounds weight are plentifully included, all of
local origin. The transition to the overlying loess is abrupt.

Peculiar stratum.—In one valley there is exposed a bed which,
though of small size (four feet thick, and but a few rods inextent),
possesses considerable interest from the fact that it contains peb-
bles of extra-local origin (granite, etc.). It intervenes between
the stratified beds and the loess and is sharply distinguished from
both. It is entirely unstratified, but presents a somewhat mot-
tled appearance due to the imperfect mingling of the component
elements, sand, clay, etc. It also contains stones of local origin
not exceeding a few pounds weight. Its position both strati-
graphically and topographically is such that it cannot be referred

wrested from its place as glaciers are accustomed to wrest a portion of their burden
the suspicion of an origin by creep or slide or wash, or at least of some origin other
than glacial, is invited.

But in view of the recent article by Mr. Frederick W. Sardeson in the December
number of the American Geologist, in which the occurrence of glaciation in the drift-
less area is confidently announced on the basis of much more limited studies than
those of Mr. Squier, and upon formations much more open to doubt than those near
Tomah and Trempealeau, since they are described as wholly composed of sandstone,
chert and earthy matter all referable to the residuary class, while the crowns of the
ridges which closely overlook the valley on both sides are limestone, it is obvious that
it might be unjust to Mr. Squier to urge longer search for the desired critical data
before publication. It is even possible that this urgency in the past and the delay in
the publication of his observations may not be free from the appearance of injustice.
But fortunately the good judgment of geologists does not, in the better habit of today,
rest much upon technical priority, but almost wholly upon the care and the complete-
ness of the investigation. It has seemed only fair to Mr. Squier, however, to state
thus fully the extent of his studies and the occasion of the delay in their published

appearance.
T. C. CHAMBERLIN.

828 Gi tale SQW

to the time of the river gravels, but must be assigned to some
earlier period.

Unstratified beds.— Overlaid by the stratified beds where they
occur, otherwise by the loess, are certain deposits, which more
especially form the subject of this article. They are confined to
the valleys, where they have a much greater range than the strat-
ified beds, reaching from two hundred feet or more above
present river level to an unknown depth below. They consist
characteristically of an aggregation of stones large and small
together with the finer material forming the matrix. Although
there is a considerable range of variation in the abundance and
average size of the stones, in the relative abundance of the differ-
ent kinds, and in the composition of the matrix, the general facies
remains very constant. All the material so far as discovered is
of local origin. Owing to a variety of circumstances it is diffi-
cult to give the thickness with anything like accuracy.

Details of structure will be best shown in the course of a
description of the various exposures. The beds are for the most
part entirely concealed from observation by the overlying depos-
its. It is only in the vicinity of the river where the latter have
been wholly or partly removed, or where a deep ravine has pene-
trated to them that they can be studied.

Descriptive details —The most extensive exposures occur about
a mile and a half west of Trempealeau village. A sketch map
of the locality is given in Fig. 1. At this point'two old valleys
converge so that they partly unite along the river front. The
lower parts of these valleys (shown in outline on the map) have
been filled up so that the drainage has been deflected, resulting in
the formation of new gorges through the rock. Wherever these
fillings are open to observation they are seen to consist of unstrat-
ified beds having the general characteristics above described.
In the east valley loess occurs down to the bottom of the ravine
above the filling, many feet below its crest.

The west valley offers rather the most favorable conditions
for observation and section 2, Fig. 2, is taken along its axis. The
filling takes the form of a well marked ridge extending across

THE DRIFTLESS REGION OF WISCONSIN 829
It is considerably broader and higher at the east

the old valley. i
end. At the west end it has been considerably encroached upon
At this end where it abuts against the

by the torrent course.

Figure 7
CE WAVY,
= Y ! =a be
SS Bz =) -
= = AWW |/7-—
: cas ZZ \ y, Wy cea
BAS My
eS i
PASS
a =
AW == =
“\ SS
fe =
= =
ey => \l WZ
2 c K A= =
ae SS
SAIN My gMis8 IX), sone Wir a eS
SQ Jarnann 2 =,
= AZ. —ZA\\\
Tee Sy ea Se Fe
= ES Ze
i . Out-

Fic. 1.— Sketch of map of vicinity of Trempealeau, Wis., described in text
wg, Rock gorge of west valley; eg, Rock gorge of east

lines of valleys in broken lines
valley; a, Point composed of large rock masses ; 4, Transvesre ridge ; ¢, Filling of east
valley; d, Outlying low knob; ss, Sandstone plateaus ; w-, yz, Lines of sections
side of the valley, it meets a projecting spur from the hills, and
et Suk

through this spur the upper end of the rock gorge passes
face indications show that material similar to the ridge extends
down the east side of the valley as far at least as the low knoba,
Fig.1, but its center along the line of section is occupied by nearly
On the west side gullies show that a bowlder bed

pure sand.

830 G. H. SQUIER

probably exists a few feet below the surface. Above the ridge
loess begins and covers all the upper part of the valley. It is
seen in the bottom of the ravine asit skirts the ridge, some twenty
feet below its crest.

From the knob da concealed ridge extends toward the river
terminating in the prominent point a. The front of the point is
lined with very large masses of rock reaching up to six or seven
tons in weight. Excavations show that the entire ridge is com-
posed of like material. The largest masses are usually sandstone.
Chert is abundant and all the local rocks are represented. Sand
covers the ridge to a depth of two to three feet and fills the
valleys on either side to an unknown depth. The general direc-
tion of the ridge is shown by occasional protruding bowlders.
As shown on the map, this ridge extends almost entirely across
the course of the east valley. Yetits direction and other cir-
cumstances seem to indicate that it belongs structurally to both
valleys.

About half a mile east of the two valleys just described
occurs another, the largest in the Trempealeau bluffs. (It is
the one in which the bed containing pebbles of extra local origin
occurs. ) At its mouth, on the east side, a bowlder bed is
superimposed on the edge of a sandstone plateau (sec. 3, Fig. 2).
In the size and character of the material, in structure, etc.,
it is a ‘fairly representative example, although not as thick as
most. No similar deposit is to be seen on the other side,
although I should expect to find one under the sand. In the
upper parts of this valley some interesting sections are furnished
by washouts; owing, however, to their incompleteness they, for
the most part, leave one in doubt as to the true nature of the
structure displayed.

In one place the point of a hill has been washed away, show-
ing that at that point the hill consists of a bowlder bed of char-
acteristic type, the material being piled nearly as steeply as it
will lie. The top and sides are covered with loess. The entire
junction is visible, showing that the transition is as abrupt as
possible (sec. 4). It cannot be seen whether it is part of a

THE DRIFTLESS REGION OF WISCONSIN 831

ridge stretching across the valley or not. Less than a quarter
of a mile east of this valley is another small one descending
from the west side of the principal bluff. It first leaves the

Frgute Se

FMM

Sec.3

UME:

Sec.6

WA ||

Sérd rock Loose Sard meen beds Clay

Fic. 2.— Section near Trempealeau, Wis. Scale about 240 to an inch, except
in Sec. 7, which is about 65" to an inch. Datum, river level, except im Sec: 7;

confinement of the hills on the west side, at the same time
changing from a nearly westerly to a southerly direction. Along
this west side a large ridge of heavy bowlders is superimposed
on a sandstone table. As the sandstone table falls away toward

832 G. H. SQUIER

the river the ridge also descends until it becomes merged witha
bowlder bed which spreads out laterally to a moderate extent.
Along the river front, this is cut into by the railroad excavation.
The deposits are characterized throughout by the large average
size of the material (equaling in this respect the ridge a, sec. 1)
and by the abundance of limestone which forms masses at least
as large as any. A smaller bowlder ridge can be seen on the
east side after it leaves the hills.

Section 5 is made where the valley is still confined by the
hill on the east. .

Another valley, about the size and character of the last,
descends from the eastern side of the same bluff and debouches
into the center of Trempealeau village. In this case, also, a
ridge extends across a sandstone table on one side, from the
point where the valley leaves the hills. On the other side the
valley skirts the foot of one of the main bluffs where the slope
is gentle and the sides thickly covered with loess. A deep
excavation has been made into this hillside for street construc-
tion. It shows the bowlder bed extending under the loess for
a short distance, then suddenly rising into a ridge and as sud-
denly falling off. There appears to be a transverse ridge about
where the line of section (sec. 6) runs, but it is not well defined.
It is a difficult section to show.

In this valley the torrent course, after cutting through from
forty to fifty feet of loess, has cut in places fifteen or twenty
feet into the bowlder beds, thus giving opportunity for the study
of the internal structure not elsewhere obtained. As, however,
the section is not fresh it is only by much labor that it can be
made available. It shows the bowlder beds alternating with
beds of clay similar in appearance to the loess. Near the lower
end of the ravine two bowlder beds occur above the bottom of
the ravine and a hole seven feet deep in the bottom of the ravine
struck the top of a third.

The thickness of a single bed ranges from about six to ten
feet, varying considerably at different points. Roughly speak-
ing the clay partings have about the same thickness as the bowl-

THE DRIFTLESS REGION OF WISCONSIN 833

der beds. The general slope of the beds is only about one-
third that of the ravine, so that they soon disappear from view,
but further up the ravine and about thirty feet above the calcu-
lated horizon of the highest of the lower beds another one
occurs about four feet thick, the parting being all clay. There
appears to be another bed still further up.

In all the sections examined the extreme abruptness of the
transition is noteworthy, the clay up to the very line of junction
being absolutely free from stones.

Owing to the great labor of obtaining sections, and their
small extent when obtained, it is impossible to answer many
important questions regarding the form, extent, and relations of
the beds.

Section 7 is fairly representative of the aspect of the beds in
sections parallel to the valley. The relations shown at p were
worked out carefully, and are of considerable interest. The
upper bed, which terminates rather abruptly at that point, has a
matrix composed mainly of sand, while in the lower bed the
matrix is a compact clay. The transition from one to the other
is quite abrupt.

Causes. — Although I should not like to express a final opin-
ion as yet, I will, nevertheless, say that so far as the facts are
known they seem to very strongly indicate one agent, while
equally excluding others.

The agents capable of transporting material of the weight
above described are few. Some of these may be dismissed
with few words. Simple gravity, such as forms the talus of
the hills, is excluded, since all the typical examples lie far
outside its range of action. Wave action is also excluded.
Neither can shore-ice offer any adequate explanation, although
it can scarcely be doubted that it existed, and certain widely
scattered bowlders, as well as certain sharply defined small
pockets of local pebbles occasionally found embedded in the
loess, may, with great probability, be assigned to this agent.
Practically there are but two agents which need be considered.
The one is torrential, the other, glacial action, in either case

834 G. H. SQUIER

operating during a period of subsidence, more or less inter-
rupted by periods of partial reélevation.

Torrential action. — Considered in the light of inherent proba-
bility, as well as in certain general aspects, this agent is doubt-
less the one we should select. The formations are strictly
valley deposits. Torrents necessarily existed and must have
produced characteristic deposits, and some of the beds at least
might have been so formed. When, however, we take account
of specific characteristics we find very grave difficulties, such as
the transverse ridges. To account for these at all by torrential
action it is necessary to regard them as ridges of erosion, the
remains of a formation once occupying the entire upper part of
the valley. The sequence of events which would thus be indi-
cated is something as follows: (1) Subsidence, unstratified
deposits; (2) Elevation, erosion ; (3) Subsidence, stratified
beds and loess, but no unstratified beds; (4) Reélevation,
erosion.

A study of local conditions furnishes several reasons why
such a sequence of events must be regarded as violent and
improbable. I will mention but one which alone seems to me
to be fatal to it. As already stated, in the west valley above
the ridge:

a. The loess covers everything high and low, even to the
bottom of recent gullies, within a couple of rods of the upper
end of the gorge, and a foot or two higher than its rock floor.
Unless, therefore, we suppose that the gorge has received no
appreciable deepening since the last elevation we must suppose
that the early erosion extended deeper above the gorge than in
the gorge itself. (How much deeper the loess extends, I do
not know.)

b. The lateral ridges.— Not to occupy too much space I will
refer to but one, the ridge marked aon the map. Assuming the
two valleys to have been filled to the height of the ridge we
should have to account for the removal of a very large amount
of material, exceeding in the west valley the amount removed
from its own gorge, yet its drainage area as compared with that

THE DRIFTLESS REGION OF WISCONSIN 835

of the gorge is only as about I to 100. It would, morever, be
necessary to account for the removal of material to a point con-
siderably below present river level, which could only have been
possible during a period of greater elevation, of which the gorge
gives no indication.

c. There is excellent reason for believing that no torrents
could have existed in these valleys capable of transporting the
heavy bowlders found in the deposits. Of course I do not deny
that torrents of sufficient power exist. I simply assert that in
this as in all cases the question must be decided on the basis of
local conditions. During the years that I have been familiar
with the locality there have occurred several very heavy rains,
and one of terrible severity, but never have I seen material
transported reaching even the hundredth part of the weight of
masses occurring in the deposits in question.

Moreover, a degree of subsidence sufficient to have allowed
these deposits by such agency would have brought the valleys
into the condition of broad flats with gentle slopes in which
powerful torrential action would have been out of the question.
We have also in the stratified beds, deposits formed under the
conditions assumed, and having the characteristics we should
expect.

Local glaciers.— That these, if we can suppose them to have
existed, could have produced the specific effects above described,
will not, I think, be questioned. I will, therefore, confine fur-
ther remarks to facts having a negative bearing. Some of these
have been anticipated in speaking of those favoring torrential
agency. A further fact is that no undoubted case of glacial
polishing or striation has yet been found, either on transported
material or on the valley walls. The force of the objection is,
however, practically destroyed by the fact that so far I have
found only three exposures of rock so situated as to have fallen
within the range of glacier action, while the transported mate-
rial in sight, has been carried but a short distance and the
greater share of that over beds of earlier deposit.

A more serious objection might be based on the general

836 G. H. SQUIER

insufficiency of the conditions for the production of glaciers.
The present maximum height of Trempealeau bluff is but 548
feet above the river. It was, of course, less at that time in propor-
tion to the amount of submergence.

But even were the elevation sufficient to allow of the forma-
tions of snow fields on the hilltops, and not elsewhere, still as
most of the hills are little more than sharp ridges it would be
quite impossible that the snow fields should have possessed
volume sufficient to originate glaciers.

My own opinion is that under the influence of the wind the
valleys themselves received a much larger annual accumulation
of snow than would fall on the level, which, should it exceed in
amount that which could be melted during the summer, would
in time fill the valleys.

This suggests the further question whether were the valleys
so filled there would be sufficient weight in the mass to give rise
to glacial motion. A partial answer seems to be found in the
small glaciers separated by Mt. Muir from the Sierra Nevada
near the Yosemite Valley, which ‘‘have the structure and motion
of true glaciers, but the largest is not more than a mile in length,
and they vary in width from half a mile to a few feet.’”’ Some
of those are therefore certainly smaller than the smallest indi-
cated in this vicinity. Further information along this line would,

however, be very desirable.
G. H. Souier.

STUDIES FOR STUDENTS.

THE METHOD OF MULTIPLE WORKING
FY PORHIESES?

THERE are two fundamental modes of study. The one is an
attempt to follow by close imitation the processes of previous
thinkers and to acquire the results of their investigations by
memorizing. It is study of a merely secondary, imitative, or
acquisitive nature. In the other mode the effort is to think
independently, or at least individually. It is primary or crea-
tive study. The endeavor is to discover new truth or to make a
new combination of truth or at least to develop by one’s own
effort an individualized assemblage of truth. The endeavor is
to think for one’s self, whether the thinking lies wholly in the
fields of previous thought or not. It is not necessary to this
mode of study that the subject-matter should be new. Old
material may be reworked. But it is essential that the process
of thought and its results be individual and independent, not the
mere following of previous lines of thought ending in predeter-
mined results. The demonstration of a problem in Euclid pre-
cisely as laid down is an illustration of the former; the demon-
stration of the same proposition by a method of one’s own or in
a manner distinctively individual is an illustration of the latter,
both lying entirely within the realm of the known and old.

Creative study however finds its largest application in those
subjects in which, while much is known, more remains to be
learned. The geological field is preéminently full of such sub-

1A paper on this subject was read before the Society of Western Naturalists in
1892, and was published in a scientific periodical. Inquiries for the article have recently
been such as to lead to the belief that a revision and republication are desirable. The
article has been freely altered and abbreviated so as to limit it to aspects related to

geological study.
837

838 STUDIES FOR STUDENTS

jects, indeed it presents few of any other class. There is prob-
ably no field of thought which is not sufficiently rich in such
subjects to give full play to investigative modes of study.

Three phases of mental procedure have been prominent in
the history of intellectual evolution thus far. What additional
phases may be in store for us in the evolutions of the future it
may not be prudent to attempt to forecast. These three phases
may be styled the method of the ruling theory, the method of
the working hypothesis, and the method of multiple working
hypotheses.

In the earlier days of intellectual development the sphere of
knowledge was limited and could be brought much more nearly
than now within the compass ofa single individual. As a natural
result those who then assumed to be wise men, or aspired to be
thought so, felt the need of knowing, or at least seeming to
know, all that was known, as a justification of their claims. So
also as a natural counterpart there grew up an expectancy on
the part of the multitude that the wise and the learned would
explain whatever new thing presented itself. Thus pride and
ambition on the one side and expectancy on the other joined
hands in developing the putative all-wise man whose knowledge
boxed the compass and whose acumen found an explanation for
every new puzzle which presented itself. Although the pre-
tended compassing of the entire horizon of knowledge has long
since become an abandoned affectation, it has left its representa-
tives in certain intellectual predilections. As in the earlier days,
so still, it is a too frequent habit to hastily conjure up an expla-
nation for every new phenomenon that presents itself. Inter-
pretation leaves its proper place at the end of the intellectual
procession and rushes to the forefront. Too often a theory is
promptly born and evidence hunted up to fit in afterward. Laud-
able as the effort at explanation is in its proper place, it is an
almost certain source of confusion and error when it runs before
a serious inquiry into the phenomenon itself. A strenuous
endeavor to find out precisely what the phenomenon really is
should take the lead and crowd back the question, commend-

METHOD OF MULTIPLE WORKING HYPOTHESES 839

able at a later stage, ‘‘ How came this so?”’ First the full facts,
then the interpretation thereof, is the normal order.

The habit of precipitate explanation leads rapidly on to the
birth of general theories.t When once an explanation or spe-
cial theory has been offered for a given phenomenon, self-con-
sistency prompts to the offering of the same explanation or
theory for like phenomena when they present themselves and
there is soon developed a general theory explanatory of a large
class of phenomena similar to the original one. In support of
the general theory there may not be any further evidence or
investigation than was involved in the first hasty conclusion.
But the repetition of its application to new phenomena, though
of the same kind, leads the mind insidiously into the delusion
that the theory has been strengthened by additional facts. A
thousand applications of the supposed principle of levity to the
explanation of ascending bodies brought no increase of evidence
that it was the true theory of the phenomena, but it doubtless
created the impression in the minds of ancient physical philoso-
phers that it did, for so many additional facts seemed to harmo-
nize with it.

For a time these hastily born theories are likely to be held
in a tentative way with some measure of candor or at least some
self-illusion of candor. With this tentative spirit and measur-
able candor, the mind satisfies its moral sense and deceives itself
with the thought that it is proceeding cautiously and impartially
toward the goal of ultimate truth. It fails to recognize that no
amount of provisional holding of a theory, no amount of applica-
tion of the theory, so long as the study lacks in incisiveness and
exhaustiveness, justifies an ultimate conviction. It is not the
slowness with which conclusions are arrived at that should give
satisfaction to the moral sense, but the precision, the complete-
ness and the impartiality of the investigation.

*T use the term theory here instead of hypothesis because the latter is associated
with a better controlled and more circumspect habit of the mind. This restrained
habit leads to the use of the less assertive term hypothesis, while the mind in the habit
here sketched more often believes itself to have reached the higher ground of a theory
and more often employs the term theory. Historically also I believe the word theory
was the term commonly used at the time this method was predominant.

840 SLODIES FOR STUDEN FS

It is in this tentative stage that the affections enter with
their blinding influence. Love was long since discerned to be
blind and what is true in the personal realm is measurably true
in the intellectual realm. Important as the intellectual affec-
tions are as stimuli and as rewards, they are nevertheless dan-
gerous factors in research. All too often they put under strain
the integrity of the intellectual processes. —The moment one has.
offered an original explanation for a phenomenon which seems
satisfactory, that moment affection for his intellectual child
springs into existence, and as the explanation grows into a definite
theory his parental affections cluster about his offspring and it
grows more and more dear to him. While he persuades himself
that he holds it still as tentative, it is none the less lovingly tenta-
tive and not impartially and indifferently tentative. So soon as
this parental affection takes possession of the mind, there is apt
to be a rapid passage to the unreserved adoption of the theory.
There is then imminent danger of an unconscious selection and
of a magnifying of phenomena that fall into harmony with the
theory and support it and an unconscious neglect of phenomena
that fail of coincidence. The mind lingers with pleasure upon
the facts that fall happily into the embrace of the theory, and
feels a natural coldness toward those that assume a refractory
attitude. Instinctively there is a special searching-out of phe-
nomena that support it, for the mind is led by its desires. There
springs up also unwittingly a pressing of the theory to make it
fit the facts and a pressing of the facts to make them fit the
theory. When these biasing tendencies set in, the mind rapidly
degenerates into the partiality of paternalism. The search for
facts, the observation of phenomena and their interpretation are
all dominated by affection for the favored theory until it appears
to its author or its advocate to have been overwhelmingly estab-
lished. The theory then rapidly rises to a position of control in
the processes of the mind and observation, induction and inter-
pretation are guided by it. From an unduly favored child it
readily grows to be a master and leads its author whithersoever
it will. The subsequent history of that mind in respect to that

METHOD OF MULTIPLE WORKING HYPOTHESES 841

theme is but the progressive dominance of a ruling idea. Briefly
summed up, the evolution is this: a premature explanation passes
first into a tentative theory, then into an adopted theory, and
lastly into a ruling theory.

When this last stage has been reached, unless the theory
happens perchance to be the true one, all hope of the best results
is gone. To be sure truth may be brought forth by an investi-
gator dominated by a false ruling idea. His very errors may
indeed stimulate investigation on the part of others. But the
condition is scarcely the less unfortunate.

As previously implied, the method of the ruling theory occu-
pied a chief place during the infancy of investigation. It is an
expression of a more or less infantile condition of the mind. I
believe it is an accepted generalization that in the earlier stages
of development the feelings and impulses are relatively stronger
than in later stages.

Unfortunately the method did not wholly pass away with the
infancy of investigation. It has lingered on, and reappears in
not a few individual instances at the present time. It finds illus-
tration in quarters where its dominance is quite unsuspected by
those most concerned.

The defects of the method are obvious and its errors grave
If one were to name the central psychological fault, it might be
stated as the admission of intellectual affection to the place
that should be dominated by impartial, intellectual rectitude
alone.

So long as intellectual interest dealt chiefly with the intangi-
ble, so long it was possible for this habit of thought to
survive and to maintain its dominance, because the phenom-
ena themselves, being largely subjective, were plastic in the
hands of the ruling idea; but so soon as investigation turned
itself earnestly to an inquiry into natural phenomena whose
manifestations are tangible, whose properties are inflexible, and
whose laws are rigorous, the defects of the method became
manifest and an effort at reformation ensued. The first great
endeavor was repressive. The advocates of reform insisted that

842 SRODIES HORTONS)

theorizing should be restrained and the simple determination of
facts should take its place. The effort was to make scientific
study statistical instead of causal. Because theorizing in nar-
row lines had led to manifest evils theorizing was to be con-
demned. The reformation urged was not the proper control
and utilization of theoretical effort but its suppression. We do
not need to go backward more than a very few decades to find
ourselves in the midst of this attempted reformation. Its weak-
ness lay in its narrowness and its restrictiveness. There is no
nobler aspiration of the human intellect than the desire to com-
pass the causes of things. The disposition to find explanations
and to develop theories is laudable in itself. It is only its ill-
placed use and its abuse that are reprehensible. The vitality of
study quickly disappears when the object sought is a mere collo-
cation of unmeaning facts.

The inefficiency of this simply repressive reformation becom-
ing apparent, improvement was sought in the method of the
working hypothesis. This has been affirmed to be che scientific
method. But it is rash to assume that any method is ¢#e method,
at least that it is the ultimate method. The working hypothesis
differs from the ruling theory in that it is- used as a means of
determining facts rather than as a proposition to be established.
It has for its chief function the suggestion and guidance of lines
of inquiry; the inquiry being made, not for the sake of the
hypothesis, but for the sake of the facts and their elucidation.
The hypothesis is a mode rather than anend. Under the ruling
theory, the stimulus is directed to the finding of facts ‘for the
support of the theory. Under the working hypothesis, the facts
are sought for the purpose of ultimate induction and demonstra-
tion, the hypothesis being but a means for the more ready devel-
opment of facts and their relations.

It will be observed that the distinction is not such as to pre-
vent a working hypothesis from gliding with the utmost ease
into a ruling theory. Affection may as easily cling about a
beloved intellectual child when named an hypothesis as if
named a theory, and its establishment in the one guise may

METHOD OF MULTIPLE WORKING HYPOTHESES 843

become a ruling passion very much as in the other. The his-
torical antecedents and the moral atmosphere associated with
the working hypothesis lend some good influence however
toward the preservation of its integrity.

Conscientiously followed, the method of the working hypoth-
esis is an incalculable advance upon the method of the ruling
theory; but it has some serious defects. One of these takes
concrete form, as just noted, in the ease with which the hypoth-
esis becomes a controlling idea. To avoid this grave danger, the
method of multiple working hypotheses is urged. It differs
from the simple working hypothesis in that it distributes the
effort and divides the affections. It is thus in some measure
protected against the radical defect of the two other methods.
In developing the multiple hypotheses, the effort is to bring up
into view every rational explanation of the phenomenon in hand
and to develop every tenable hypothesis relative to its nature,
cause or origin, and to give to all of these as impartially as pos-
sible a working form and a due place in the investigation. The
investigator thus becomes the parent of a family of hypotheses ;
and by his parental relations to all is morally forbidden to fasten
his affections unduly upon any one. In the very nature of the
case, the chief danger that springs from affection is counter-
acted. Where some of the hypotheses have been already pro-
posed and used, while others are the investigator’s own creation.
a natural difficulty arises, but the right use of the method requires
the impartial adoption of all alike into the working family. The
investigator thus at the outset puts himself in cordial sympathy
and in parental relations (of adoption, if not of authorship, ) with
every hypothesis that is at all applicable to the case under inves-
tigation. Having thus neutralized so far as may be the partiali-
ties of his emotional nature, he proceeds with a certain natural
and enforced erectness of mental attitude to the inquiry, know-
ing well that some of his intellectual children (by birth or adop-
tion) must needs perish before maturity, but yet with the hope
that several of them may survive the ordeal of crucial research,
since it often proves in the end that several agencies were con-

$44 SLUDIES FOR STUDENTS

joined in the production of the phenomena. Honors must often
be divided between hypotheses. One of the superiorities of
multiple hypotheses as a working mode lies just here. In fol-
lowing a single hypothesis the mind is biased by the presump-
tions of its method toward a single explanatory conception.
But an adequate explanation often involves the codrdination of
several causes. This is especially true when the research deals
with aclass of complicated phenomena naturally associated, but
not necessarily of the same origin and nature, as for example
the Basement Complex or the Pleistocene drift. Several agen-
cies may participate not only but their proportions and impor-
tance may vary from instance to instance in thesame field. The
true explanation is therefore necessarily complex, and the ele-
ments of the complex are constantly varying. Such distributive
explanations of phenomena are especially contemplated and
encouraged by the method of multiple hypotheses and consti-
tute one of its chief merits. For many reasons we are prone to
refer phenomena to a single cause. It naturally follows that
when we find an effective agency present, we are predisposed to
be satisfied therewith. We are thus easily led to stop short of
full results, sometimes short of the chief factors. The factor
we find may not even be the dominant one, much less the full
complement of agencies engaged in the accomplishment of the
total phenomena under inquiry. The mooted question of the
origin of the Great Lake basins may serve as an illustration.
Several hypotheses have been urged by as many different stu-
dents of the problem as the cause of these great excavations.
All of these have been pressed with great force and with an
admirable array of facts. Up to a certain point we are com-
pelled to go with each advocate. It is practically demonstrable
that these basins were river valleys antecedent to the glacial
incursion. It is equally demonstrable that there was a blocking
up of outlets. We must conclude then that the present basins
owe their origin in part to the preéxistence of river valleys and
to the blocking up of their outlets by drift. That there is a
temptation to rest here, the history of the question shows. But

METHOD OF MULTIPLE WORKING HYPOTHESES 845

on the other hand it is demonstrable that these basins were
occupied by great lobes of ice and were important channels of
glacial movement. The leeward drift shows much material
derived from their bottoms. We cannot therefore refuse assent to
the doctrine that the basins owe something to glacial excavation.
Still again it has been urged that the earth’s crust beneath these
basins was flexed downward by the weight of the ice load and
contracted by its low temperature and that the basins owe some-
thing to crustal deformation. This third cause tallies with cer-
tain features not readily explained by the others. And still it is
doubtful whether all these combined constitute an adequate
explanation of the phenomena. Certain it is, at least, that the
measure of participation of each must be determined before a
satisfactory elucidation can be reached. The full solution there-
fore involves not only the recognition of multiple participation
but an estimate of the measure and mode of each participation.
For this the simultaneous use of a full staff of working hypoth-
esesis demanded. The method of the single working hypothesis
or the predominant working hypothesis is incompetent.

In practice it is not always possible to give all hypotheses
like places nor does the method contemplate precisely equable
treatment. In forming specific plans for field, office or laboratory
work it may often be necessary to follow the lines of inquiry
suggested by some one hypothesis, rather than those of another.
The favored hypothesis may derive some advantage therefrom
or go to an earlier death as the case may be, but this is rather a
matter of executive detail than of principle.

A special merit of the use of a full staff of hypotheses coérdi-
nately is that in the very nature of the case it invites thorough-
ness. The value of a working hypothesis lies largely in the
significance it gives to phenomena which might otherwise be
meaningless and in the new lines of inquiry which spring from
the suggestions called forth by the significance thus disclosed.
Facts that are trivial in themselves are brought forth into impor-
tance by the revelation of their bearings upon the hypothesis
and the elucidation sought through the hypothesis. The phe-

846 STUDIES FOR STUDENTS

nomenal influence which the Darwinian hypothesis has exerted
upon the investigations of the past two decades is a monumental
illustration. But while a single working hypothesis may lead
investigation very effectively along a given line, it may in that
very fact invite the neglect of other lines equally important.
Very many biologists would doubtless be disposed today to cite
the hypothesis of natural selection, extraordinary as its influence
for good has been, as an illustration of this. While inquiry is
thus promoted in certain quarters, the lack of balance and com-
pleteness gives unsymmetrical and imperfect results. But if on
the contrary all rational hypotheses bearing on a subject are
worked coérdinately, thoroughness, equipoise, and symmetry
are the presumptive results in the very nature of the case.

In the use of the multiple method, the reaction of one
hypothesis upon another tends to amplify the recognized scope
of each. Every hypothesis is quite sure to call forth into clear
recognition new or neglected aspects of the phenomena in its
own interests, but ofttimes these are found to be important
contributions to the full deployment of other hypotheses. The
characters at the hands of

b)

eloquent expositions of ‘‘prophetic’
Agassiz were profoundly suggestive and helpful in the explica-
tion of ‘undifferentiated”’ types in the hand of the evolu-
tionary theory.

So also the mutual conflicts of hypotheses whet the discrim-
inative edge of each. The keenness of the analytic process
advocates the closeness of differentiating criteria, and the sharp-
ness of discrimination is promoted by the codrdinate working of
several competitive hypotheses.

Fertility in processes is also a ‘natural sequence. Each
hypothesis suggests its own criteria, its own means of proof,
its own method of developing the truth; and if a group of
hypotheses encompass the subject on all sides, the total outcome
of means and of methods is full and rich.

The loyal pursuit of the method for a period of years leads
to certain distinctive habits of mind which deserve more than
the passing notice which alone can be given them here. As a

Rae

METHOD OF MULTIPLE WORKING HYPOTHESES 847

factor in education the disciplinary value of the method is one
of prime importance. When faithfully followed for a sufficient
time, it develops a mode of thought of its own kind which may
be designated the habit of parallel thought, or of complex
thought. It is contra-distinguished from the linear order of
thought which is necessarily cultivated in language and mathe-
matics because their modes are linear and successive. The pro-
cedure is complex and largely simultaneously complex. The
mind appears to become possessed of the power of simultaneous
vision from different points of view. The power of viewing
phenomena analytically and synthetically at the same time
appears to be gained. It is not altogether unlike the intellectual
procedure in the study of a landscape. From every quarter
of the broad area of the landscape there come into the mind
myriads of lines of potential intelligence which are received
and coérdinated simultaneously producing a complex impression
which is recorded and studied directly in its complexity. If the
landscape is to be delineated in language it must be taken part
by part in linear succession.

Over against the great value of this power of thinking in
complexes there is an unavoidable disadvantage. No good thing
is without its drawbacks. It is obvious upon studious consider-
ation that a complex or parallel method of thought cannot be
rendered into verbal expression directly and immediately as it
takes place. We cannot put into words more than a single line
of thought at the same time, and even in that the order of
expression must be conformed to the idiosyncrasies of the
language. Moreover the rate must be incalculably slower than
the mental process. When the habit of complex or parallel
thought is not highly developed there is usually a leading line
of thought to which the others are subordinate. Following this
leading line the difficulty of expression does not rise to serious
proportions. But when the method of simultaneous mental
action along different lines is so highly developed that the
thoughts running in different channels are nearly equivalent,
there is an obvious embarrassment in making a selection for

848 STUDIES FOR STUDENTS

verbal expression and there arises a disinclination to make the
attempt. Furthermore the impossibility of expressing the
mental operation in words leads to their disuse in the silent pro-
cesses of thought and hence words and thoughts lose that close
association which they are accustomed to maintain with those
whose silent as well as spoken thoughts predominantly run in
linear verbal courses. There is therefore a certain predisposition
on the part of the practitioner of this method to taciturnity.
The remedy obviously lies in codrdinate literary work.

An infelicity also seems to attend the use of the method
with young students. It is far easier, and apparently in general
more interesting, for those of limited training and maturity to
accept a simple interpretation or a single theory and to give it
wide application, than to recognize several concurrent factors
and to evaluate these as the true elucidation often requires.
Recalling again for illustration the problem of the Great Lake
basins, it is more to the immature taste to be taught that these
were scooped out by the mighty power of the great glaciers than
to be urged to conceive of three or more great agencies working
successively in part and simultaneously in part and to endeavor
to estimate the fraction of the total results which was accom-
plished by each of these agencies. The complex and the quan-
titative do not fascinate the young student as they do the veteran
investigator.

The studies of the geologist are peculiarly complex. It is
rare that his problem is a simple unitary phenomenon explicable
by a single simple cause. Even when it happens to be so in a
given instance, or at a given stage of work, the subject is quite
sure, if pursued broadly, to grade into some complication or
undergo some transition. He must therefore ever be on the alert
_ for mutations and for the insidious entrance of new factors. If
therefore there are any advantages in any field in being armed
with a full panoply of working hypotheses and in habitually
employing them, it is doubtless the field of the geologist.

T. C. CHAMBERLIN.

PDT ORIAL.

Tue laudable efforts of the Russian geologists to make the
proceedings of the seventh session of the International Geolog-
ical Congress contribute materially to the advancement of the
science along the lines of unification and reformation of classifi-
cations and nomenclatures met with but partial success. The
number of papers presented that bore directly on these problems
was not large and their magnitude was inconsiderable. Never-
theless it will appear in the future that the effort was much more
fruitful than seemed at the time to be the case. The results in
connection with the classification and nomenclature of stratified
formations were more immediate and satisfactory than those
relating to the same problems in petrography. Messrs. Frech
and Bittner prepared papers that led to the formulation by
Messrs. Karpinsky and Tschernyschew of definite propositions
for the establishment of principles upon which may be based
rules for the creation and use of stratigraphical terms. These
were discussed by the congress and agreed to in part. A new
committee was appointed to consider the principles of chrono-
logical classification of sedimentary formations. The committee
consists of active members and of consulting members. The
former are: Messrs. Barrois, Capellini, Hughes, Renevier, Tietze,
Tschernyschew, H.S. Williams, Zittel. Consulting members are:
Choffat, Clark, Cortazar, Davy, Dawson, Déperet, Frech, Gries-
bach, Karpinsky, Kayser, de Lapparent, Martin, Mayer-Eymar,
Nathorst, Nikitin, Stefanescu, De-Stefani, Taramelli, Uhlig, Van
der Broeck, Walcott, Woodward.

*
x

The results in connection with the problem of the reformation
of petrographic nomenclature were most disappointing to the
849

850 EDITORIAL

Russian geologists, partly by reason of the fewness of the papers
contributed and partly because of the resolution passed by the
petrographers present that the time had not arrived for the deter-
mination of general principles for the classification and nomen-
clature of rocks. This, together with the absence of any report
from the committee appointed at the sixth session of the congress
prevented a discussion of principles and appeared to be a direct
reproof of the geologists who had suggested the discussion. It
should not be so considered. It was in fact an indication of the
wide divergence of opinion on the subject of classification and
nomenclature among petrologists and of the consciousness of the
rapid changes that are taking place in our knowledge of the
elements involved, which would render hasty deliberation fruit-
less. But there is no question that had a report been presented
by the committee it would have elicited a most vigorous discus-
sion. Itis to be remarked also that an effort on the part of the
petrologists to replace the former committee by a more actiye
one was voted down by the help of those geologists who appeared
most anxious to have the problem advanced. The undertaking
is of such a serious nature that few cared to offer new suggestions
without very careful consideration. Nevertheless the agitation
will undoubtedly prove beneficial, and as great advances could
be recognized to have taken place since the meeting of thesixth
session at Zurich, still greater ones may be expected by the
time of the Paris meeting, when it is hoped that the committee
will present a report which may not only form the basis for
discussion but a foundation for permanent reforms. J. P. I.

REVIEWS.

The Glacial Lake Agassiz. By WarreN UpHam. Monograph
of the United States Geological Survey, Washington, D.C.,
1895.

This opus magnum of one of our most active and worthy glacialists
has fallen between the two horns of a dilemma common enough in
the experience of the busy editor who hesitates between the hasty
sketch which alone time permits him to prepare and the careful review
which he knows he ought to prepare in due respect for the merits of
the work. ‘The choice of the latter which best suits the stress of the
hour too often proves but a renewal of the dilemma with added inten-
sity when he next recurs to the subject, and so the struggle goes on
until the alternative narrows to an inadequate notice or an unworthy
negligence of a work of merit.

This monograph of more than 650 pages, amply illustrated by
maps and diagrams, represents several years of very industrious study
of the surficial phenomena of the basin of the Red River of the north
and adjacent territory, begun under the auspices of the Minnesota
Survey and finished under those of the United States Survey with the
co6peration of the Canadian Survey.

The treatment is systematic and detailed. Beginning with a gen-
eral introduction it passes to the topography of the basin which is
minutely described, after which the underlying formations embracing
the Archean, the two Silurians, and the Cretaceous, are discussed at
some length. The glacial period and its drift deposits are treated
with still more fullness because of their immediate relations to the
history of Lake Aggasiz. This is introduced by a review of the
glacial period in North America, and a comprehensive sketch of
the continental ice-sheet which is illustrated by an excellent map
showing not only the general distribution of North American Pleisto-
cene glaciation as known at the time of its preparation, but also the

directions of movement in various parts of the great area. Greenland
851

852 REVIEWS

and the Archipelago north of the continent are included. The Lau.
rentide and Cordilleran ice-sheets are differentiated and the debatable
belt between them indicated. The Keewatin ice-sheet which has since
been differentiated from the Laurentide glacier in part at least by
Tyrrell is, of course, not separately represented. The recession of the
ice-sheet and the courses of the ice movement in the immediate vicin-
ity of Lake Agassiz are very fully set forth, as well as the drift
deposits of the region. The succession of terminal moraines is amply
delineated by text and maps. The moraines from the seventh or
Dovre to the eleventh or Mesabi are regarded as contemporaneous
with Lake Agassiz.

With this very ample but needful introduction the history of Lake
Agassiz is delineated. A distinction is drawn between the Great Basin
lakes, Bonneville, Lahontan, and others, and true glacial lakes of the
Agassiz type. The indubitable evidences of the existence of the lake
in a well-cut outlet, eroded cliffs, beaches, deltas, and lacustrine
deposits, are set forth in general terms at the outset and taken up in
much detail afterwards.

The contemporaneity of the great ice-sheet and the dependence of
the lake upon the ice mass for its northern barrier is a central point
of interest in the monograph. ‘The changes in the history of the lake
are made dependent upon the shifting position of this ice barrier,
upon the erosion of the outlet, and upon progressive changes in the
earth’s surface. An attempt is made to measure the duration of Lake
Agassiz by means of its beaches, its moraines, and correlated phe-
nomena, with the result that the period is believed to have been short
and the formation of the moraines very rapid. Some alternative inter-
pretations by Chamberlin, under whose direction the work was
prosecuted, are introduced at this point at the request of the author,
the chief purport of which is to assign a series of rising as well as fall-
ing stages to the shores of Lake Agassiz and to thereby make the
moraines antedate the highest beach and to leave the time occupied
in their formation undetermined.

The beaches are divided into two classes, the one set being those
connected with the southern outlet at Lake Traverse and the other
set those connected with some undetermined outlet to the northward.
Five distinct stages, represented by as many beaches or groups of
beaches, belong to the first set and four to the second. One of the
most important features of the monograph is the accurate determina-

REVIEWS 853

tion of very notable changes in the level of these beaches. A former
relative rise of the surface to the northeast is not only amply demon-
strated, but a progressive fall of the surface at the north at later stages
until it reached its present attitude is fully made out. The move-
ment appears to have been steadily progressive and systematic. The
possible causes of these changes of levels are discussed, embracing
gravitation toward the ice-sheet which, while measurably effective, is
found quantitatively insufficient, changes in the temperature of the
earth’s crust which is also regarded as insufficient, and epeirogenic
movements apparently dependent in part upon glaciation, which is
regarded as the essential agency. In this connection the author
extends his discussion widely, treating of the preglacial elevation of
North America, as shown by fiords and submarine valleys and of the
late glacial or Champlain submergence shown by fossiliferous marine
beds overlying glacial deposits, and from these he endeavors to deduce
the Pleistocene dscillations embracing those which were independent
of glaciation as well as those dependent upon it. He maintains his
well-known views regarding the dependence of glaciation essentially
upon epeirogenic movements.

The monograph closes with chapters on the artesian and common
wells of the Red River valley and the agricultural and mineral
resources of the area of Lake Agassiz. There are added appendices
giving the courses of glacial striz and notes on aboriginal earth works
within or near the area of the lake. The whole material is worked
out with care and great detail and constitutes a very important con-
tribution to Pleistocene history in both its glacial and its lacustrine
aspects. T.Ca@

Catalogue of the Tertiary Mollusca in the Department of Geology,
British Museum (Natural History). Part 1. The Austra-
lasian Tertiary Mollusca. By GreorGe F. Harris, F.G.S.
407 pp., 8 pls. London, 1897.

The British Museum, which has in process of publication cata-
logues of its great collections, has lately started a new series upon the
Tertiary Mollusca, under the editorship .of Professor Harris. The
first volume dealing with the Australasian forms has just made its
appearance. The acquisition by the Museum at different times since

854 REVIEWS

1860 of large numbers of Teritary mollusca from Australia and New
Zealand, has made it possible for Professor Harris to present a very
exhaustive review of the subject, the Gasteropoda particularly being
described in great detail. The fine state of preservation of the speci-
mens has led the author to consider the several forms both from an
ontogenetic and phylogenetic standpoint, and as so little work of this
character has been done on the Gasteropoda, hitherto, it must prove
of fundamental importance in the systematic classification of this class
of the mollusca.

The book contains a complete synonomy ofall the forms catalogued,
together with a description of such new material as the Museum pos-
sesses. The admirable figures which accompany the volume show in
great detail the protoconchs of many of the Gasteropod types.

This report presents the first thoroughly systematic treatment of
the Tertiary molluscan faunas of Australasia and will be of great serv-
ice to the student of Tertiary mollusca in other portions of the world.
Volume I -will be succeeded by others in which the large Tertiary
collections of the British Museum from other lands will be minutely
described. There is no man better able to undertake this task than
Professor Harris, as he is intimately acquainted with the Tertiary in
many portions of the world, and probably has a more comprehensive
knowledge of the Tertiary of central and western Europe than any
one living. He has published an important memoir on the Eocene
geology and paleontology of the Paris Basin, besides making contri-
butions to the Tertiary of England.

The future publications of this series will be awaited with much

interest by all students of Tertiary paleontology.
Wo. B. CiargK.

Transactions of the American Institute of Mining Engineers, Vol.
XXVI, February 1896, to October 1896 inclusive. Pub-
lished by the Institute, New York City, 1897.

This number of the Zyansactions presents a goodly list of papers
of especial interest to geologists. Of these we may mention the fol-
lowing :

The Ore Deposits of the Austrahan Broken Fiill Consols Mine,
Broken Hill, New South Wales. By GrorGE SMITH, pp. 69-78. This

REVIEWS 855

is an interesting discussion on the concentration of dyscrasite and
antimonial silver chloride where the lode is cut by cross veins or
“indicators.” The author finds it necessary to invoke the aid of the
electro-magnetic currents of the earth’s crust acting along the cross
veins to account for this particular form of deposition.

Copper Ores in the Permian of Texas. By E. J. SCHMITZ, JR., pp.
97-108 (discussion p. 1051). The copper ores of the Texas Permian
occur as pseudomorphs of wood or as nodules or copper-bearing shale,
slate or clay, and was deposited under much the same conditions as the
“« Hupperschiefer” in the German Permian, the chief difference being
that the American ore is in the main a carbonate or silicate, while the
German is a sulphide.

Vein Walls. By T. A. RICKARD, pp. 193-241 (discussion p.
1153). A valuable dissertation upon the relation of ore deposition
to the composition and structure of the inclosing strata.

Sketch of a Portion of the Gunnison Gold Belt, Including the Vulcan
and Mammoth Chimney Mines. By ARTHUR LAKES, pp 440-448.

Gold in Granite and Plutonic Rocks. By Wi LLiAM P. BLAKE, pp.
290-298. A summary of a number instances of the occurrence of
gold as a primary constituent of granite and plutonic rocks.

Faulting and Accompanying Features Observed in Glacial Gravel and
Sand in Southern Michigan. By Cart HENRICH, pp. 460-464 (discus-
sion p. 1102). The faulting occurs in stratified gravel. The fault planes
are from seven to twelve feet apart, and none have a throw of less than
seven inches. Along these fault planes nodules have been formed
by ascending currents of water. The explanation offered is that lateral
pressure was caused by two glaciers converging along Silver Creek and
Goose Greek valleys.

Further Notes on the Alabama and Georgia Gold-Fields. By
WILLIAM H. BREWER, pp. 464-472.

The Ore-Shoots of Cripple Creek, Colorado. By EDWARD SKEWES,
pp. 553-579. A detailed description of the ore-shoots of a portion of the
Cripple Creek district, and their relations to the vein fissures.

Traces of Organic Remains from the Hurontan (2) Sertes at the Tron
Mountain, Michigan, etc. By W. S. GREESLEY, pp. 527-534. An
account of the author’s discovery of certain markings on the iron ore

856 REVIEWS

upon the docks at Erie, Pa. which he indentifies as fossil remains.
Three plates follow the article.

The Phosphate Deposits of Arkansas. By JOHN C. BRANNER, pp.
580-598. The phosphate deposits are reported in or associated with a
narrow zone either of greenish or black shale, or a sandstone deposited
between recognized Lower Silurian and Carboniferous strata. This
interval represents the slow accumulation of organic matter in acom-
paratively deepsea. Phosphate nodules have also been found in some
of the Cretaceous beds of the region.

Magnetic Observation in Geological Mapping. By Hrnry Lioyp
SMITH, pp. 640-709. ‘The principles of plotting magnetic observation
and applications to geological mapping, etc.

Some Mines of Rosita and Silver Cliff, Colorado. By S. F. EMMons,
pp- 773-822. The ore of the Bassic mine was deposited by fumoralic
action as a phase of the dying activity of the volcano when H,S and
5,O were the prevailing gases. The Bull-Domingo mine ores were
deposited from aqueous solutions coming from a region of igneous
eruptions close at hand.

Discussing the composition of descending surface waters and
ascending deep waters Mr. Emmons concludes, in opposition to the
prevalent belief, that decreasing temperature and pressure are not the
principal determining causes of the precipitation of vein minerals from
ascending solutions. Also that all the metallic minerals of the plateau
were formed under the same conditions and during the same general
phase of ore deposition, and their irregular dissemination is due to
physical rather than to chemical causes.

He states also that ‘‘the heavy metals have probably been brought up
from the interior of the earth within the magmas of igneous rocks, and
that by some process of differentiation not yet completely understood
either previous to, or during the process of cooling and consolidation,
they have been concentrated within certain bodies or parts of bodies
of eruptive rocks ; and, further, that ore bodies as found at the present
day are the result of a concentration (perhaps many times repeated)
of the materials thus brought up, which are in all probability very
finely disseminated through the present rock masses or combined in
minute amounts in the more common basic minerals. This seems a
more rational hypothesis, and one more in accordance with modern
scientific practice, than to content oneself with assuming simply that

REVIEWS 857

the ascending waters came charged with metallic minerals from the
bathysphere, meaning thereby a region in the interior of the earth
which is richer in heavy metals than any part of the earth’s crust
that comes under our observation ; for this simple assumption affords
no explanation why metallic minerals are concentrated in one part
of the earth’s crust and not in another, and it supposes a free flow
of waters at greater depths than in our present state of knowledge
of terrestrial physics it is considered possible that channels which
would admit ofa flow of water through them would remain open.

“Furthermore, if the vein-materials are found to form a constituent
part, even in minute traces, of comparatively fresh and unaltered
country-rocks in a given ore-bearing region, and at such distances
from any water-channels as to render it improbable that these mate-
rials could have been brought in through these channels, it is reason-
able to assume that these or similar rocks have been permeated by the
waters from which the known ore deposits were precipitated, and that
from them they derived their contained vein-materials. .... It
seems probable that not only the recent eruptives, but the older
granites through which the ascending solutions must have passed, con-
tain enough of the precious metals, and, it may be assumed also, of
the other vein-materials to furnish, in the long time that is accorded
to the accomplishment of most geological phenomena, sufficient mate-
rial of the formation of existing ore-bodies. The analysis of the
vadose waters in the Geyser mine has demonstrated the capability
possessed by even cold surface waters of taking up such materials in
their passage through the rocks. The subterranean waters that were
circulating here at the time of the formation of the ore-deposits must
have been much more energetic solvents, being heated by contact
with the cooling masses of igneous rock, and probably deriving a cer-
tain amount of active and energetic mineralizing agents, such as
fluorine, chlorine, etc., from these igneous masses at the time of con-
tact. Hence it is fair to assume that the vein-materials in this region
were originally derived from both recent and ancient eruptive rocks
—a conclusion similar to that arrived at by Mr. Penrose, from his
more exhaustive study of the ore-deposits of Cripple Creek.”

The Occurrence and Treatment of Certain Gold Ores of Park County,
Colorado. By B. SADTLER, pp. 848-853.

The Occurrence of Gold Ores in the Rainy River District, Ontario,
Canada. By Wn. H. MERRITT, pp. 853-863.

858 REVIEWS

Other papers — such for example—as The Microstructure of Steel
and the Current Theories of Hardening, by ALBERT SAUVEUR, have

direct application to the broad domin of theoretical geology.
C. F. TOLMAN Jr.

The Law of Mines and Mining tn the United States. By DANIEL
Moreau BARRINGER and JoHN StToKES ADaAms. Little,
Brown, & Co., Boston, 1897.

Although primarily a legal work this book possesses not a little
interest and value to geologists in general and especially to those
who have to deal with economic interests. It opens with a geological
preface in which the various kinds of mineral deposits that are liable
to be subjects of litigation are defined and their modes of occur-
rence and to some extent their origins are briefly stated, as these
features are often decisive in the legal classification of the formations.
The purpose of the work is to give a better appreciation of the reasons
for the established legal distinctions relative to mineral deposits, inso-
far as these are based on differences in the nature, the mode of occur-
rence or the origin of the deposits. While the matter is not new to
geologists and makes no pretension to exhaustiveness, its special point
of view gives not a little freshness to the sketch. The legal classifica-
tion of ore deposits is not without its suggestiveness to scientific
students.

The body of the book opens with a chapter on property in min-
erals where there has been no division between the ownership of the
surface and of the mineral below, followed by one on property rights
where the title to the mineral or the right to take it out is vested in
some one who is not the owner of the soil. It then treats of min-
eral leases and the rights and duties arising thereunder, and the modes
of assignment and termination of leases. Chapters follow on the
property of the sovereign and its grantees in minerals, for example,
minerals in the beds of navigable streams or under public highways or
in lands taken by eminent domain. There is also a discussion of
the government’s title and the granting thereof. A chapter is
devoted to the discovery and location of claims, another to the
extent of claims, and one each to the method by which claims are
held, to the local mining rules and regulations, to the method by
which title to mining claims may be terminated, and to the reloca-

REVIEWS 859

tion of claims; also one each to the acquiring of a title before the
patent and to the patent itself. The different kinds of claims, as
lode claims, placer claims, lodes in placers, tunnel claims, mill sites
and water right claims are systematically treated. Passing by some
chapters on special themes we may note those on the rights of mine
owners and of miners respectively, and the one on the application
of equitable principles and remedies to mining operations. An
appendix embraces the United States statutes relative to mineral
deposits and the land office regulations. A very large number of
cases are cited and briefly abstracted in illustration of the general
treatment of the several themes. tea.

The Science of Brickmaking - with some Account of the Structure
and Physical Properties of Bricks. By GrorGe F. Harris,
F.G.S. 160 pp. H. Greville Montgomery, London, 1897.

Professor Harris has presented in this little volume an admirable
elementary treatise upon the science of brickmaking, which cannot
fail to be of much value to the more intelligent class of brickmakers
and clayworkers generally. The subject is logically and systematically
discussed and is illustrated with a large number of local examples of
brick-earths. The book contains much new information upon one of
the most important economic subjects with which the geologist comes
in touch. It is significant to see a man of Professor Harris’ scientific
attainments in the more theoretical and technical phases of geology
turning his attention to so thoroughly practical a subject as that of
brickmaking. Professor Harris rightly thinks that too many geolo-
gists do not sufficiently regard the economic aspects of their science,
and he is preparing to present to the English-reading public still fur-
ther contributions upon the practical side of geology.

The book opens with a discussion of the different types of brick-
earths, which are classified as fluviatile, lacustrine and fluviatile, and
marine. Following this are chapters devoted to the mineral constitu-
tion of brick-earths, and the behavior of the various minerals in the
kiln. In this connection the author clearly points out that the chem-
ical analysis does not always afford the needed information to the
brickmaker, but that the physical constitution of the materials also
has great influence in determining the value of the brick-earth.

860 REVIEWS

The chemistry of brick-earths and the methods to be pursued in
analyzing them are considered at much length. The micro-structure
of bricks is presented in a manner to be of much aid to the practical
brickmaker who is anxious to determine the texture of his product.
The important question of the durability of bricks is also discussed.
Among the tests which are mentioned by the author are the chemical
composition of the brick, its absorptive capacity, its minute structure,
its specific gravity, and its strength. Each of these subjects is dis-
cussed in some detail.

This information cannot but be highly beneficial to the brick-
maker capable of appreciating the bearing which accurate scientific
knowledge has upon his industry. Similar treatises to that of Profes-
sor Harris, with American illustrations, would be of much value to
our own economic interests. The more our operators, whether in clay
or other mineral products, come to realize their dependence upon
scientific fact, and they will only realize it by the geologist interesting
himself in their work, the better for the success of their endeavors, and
the greater influence the scientific expert will have among practical
men generally. Wm. B. CLarK.

TNpEeee TO VOLUME V.

ABSTRACTS :
Age of the Lower Coals of Henry County, Missouri. David S. White - 218
Age of the White Limestone of Sussex County, New Jersey. J. E.

Wolff and A. H. Brooks - - - - = - - - 322
A Study of the Nature, Structure and Phylogeny of Daemonelix. E. H.

Barbour - - - - - . - . - - : 223
Complete Oil-well Record in the McDonald Field between the Pittsburg

Coal and the Fifth Oil Sand. I. C. White - - - - - 103
Cornell Glacier, Greenland. Ralph S. Tarr - - : = = 95
Crater Lake, Oregon. J. S. Diller - = : = - 219
Crystalline and Metamorphic Rocks of Northwest ieee. C. Willard

Hayes and Alfred H. Brooks - - - = - - = 210
Dikes in Appalachian Virginia. N.H. Darton - - . = - 324
Erosion at Base Level. M.R.Campbell - = - - - = s22
Geological Atlas of the United States, Folio 30, Yellowstone National

Park, Wyoming. 1896 - - - - - - - - - 405
Geological Atlas of the United States, Folio 24, Three Forks, Montana.

1896 - - - - - - : - - - - - 407
Geological Atlas of the United States, Folio 29, Nevada City, special

folio, California. 1896 - - - - - - - - - 409
Geological Atlas of the United States, Folio 26, Pocahontas, See

West Virginia. 1896 - - - - - =) = 4rd
Geological Atlas of the United States, Folio 25, Loudon, Tennessee.

1896 - - - - - - - - - - - - 416
Geological Atlas of the United States, Folio 27, Morristown, Tennessee.

1896 . - - - - - - - - - - - 417
Glacial Observations in the Umanak District, Greenland. Geo. H. Bar-

ton - - - - - - - - - - - - . 89
Grain of Rocks. Alfred C. Lane - - - - - - =i 2222
Homology of Joints and Artificial Fractures. J.B. Woodworth - - 97
Leucite Hills of Wyoming. J. F. Kemp 7 - - - - - 100
Modified Drift in St. Paul, Minnesota. Warren Upham - > ath
Nipissing-Mattawa River, the Outlet of the Nipissing Great Lakes. F.

B. Taylor - - - - - - - - - - 220
Note on the Plasticity of Glacial Ice. Israel C. Russell - - - 104
Notes on Rock Weathering. George P. Merrill - - - - - 98
Notes on the Potsdam and Lower Magnesian Formation of Wisconsin

and Minnesota. Joseph F. James - - - - - . - 99

S61

862 LN DEXE HO VOTE OME:

ABSTRACTS :
Old Tracks of Erian Drainage in Western New York. G. K. Gilbert -
Origin and Age of the Gypsum Deposits of Kansas. G.P. Grimsley -
Origin and Relations of the Grenville and Hastings Series in the Cana-
dian Laurentian. Frank D. Adams and Alfred E. Barlow - -
Origin of Certain Topographic Forms. M.R. Campbell - - =
Physical Nature of the Problem of General sete Correlation.
Charles R. Keyes” - - - - - - - - -
Pre-Cambrian Topography of the Eastern Adriondacks. J. F. Kemp -
Preliminary Note on the Pleistocene History of ee Sound. Bailey
Willis - - - - - - - - - -
Principal Features of the Geolvey of Southeastern Washington. Israel
C. Russell - : - - - - - - - -
Shore Lines of Lake Warren and of a Lower Water Level in Western
New York. H.L. Fairchild - - - - - - - -
Solution of Silica under Atmospheric Conditions. C. W. Hayes - -
Stratigraphy and Paleontology of the Laramie and Related Formations
in Wyoming. T. W. Stanton and F. H. Knowlton - - - -
Unconformities in Martha’s Vineyard and Block Island. J. B. W ood-
worth - - - - - - - - - -
United States Geol ieal Atlas, Folio 28, Piedmont, West Virginia—
Maryland, 1896 - - - - - - - - -
United States Geological Atlas, Folio 23, Nomini, Hae Virginia.

1896 - - - - - - - - - -
Upper Cretaceous of the Northern Atlantic Coastal Plain. Wm. B.
Clark - - - - - - 2 - - - -
Work of the United States Geological Seer in the Sierra Nevada. H.
W. Turner - - - - - - - = - - -

Academy of Natural Sciences, Bulletin of the Minnesota. C. W. Hall.
Review by T. C. Chamberlin - - - - - - =
Academy of Natural Sciences, Proceedings of the Davenport. Review by T
C. Chamberlin - : - - - - - - - - -
Academy of Sciences, Tee of the Iowa. Review by T. C. Cham-
berlin . - = = - - - - - =

Adams, Frank and Alfred Barlow. Origin and Relations of the Grenville
and Hastings Series in the Canadian Laurentian. (Abstract) - -

Review: Some Recent Papers on the Influence of Granitic Intrusions

upon the Development of Crystalline Schists — - - - -

Agassiz, Alexander. The Elevated Reef of Florida. Review by J. E. Wood-
man - : - - - - - - - - -
Agassiz, The Glacial Lake. Warren Upham. Review by JT. C. Cham-
berlin - - = - = : S 3 = 2 - -
Alabama, Geological Survey of. E. A. Smith. Report onthe Valley Regions.
Part II, on the Coosa Valley. H. ee Review by T. C. Cham-

berlin - - - - 2 = = - é
Analcite Basalt from Colorado. Whitman Cross - - - - - :

PAGE

413
217
105
648
649
648

92
293
312
759

646
684

INDEX TO VOLUME V 863

PAGE
Analyses - - . - : - 49, 247, 248, 252, 266, 268, 269, 352, 358, 370
Ancient Volcanoes of Great Britain. Archibald Geike. Review by J. P. Idd-
ings - - = = = - - - - - - - = S30
Ancient Volcanic Rocks of South Morristown, Pennsylvania. Florence Bas-
come. Review by J. P. Iddings - - - - - - ae 23
Andendiorite in Japan. C. Iwasaki - - - - : - - = S720
Appalachians across Mississippi, Louisiana, and Texas, The Former Extension
of the. J.C. Branner. Review by A. B. Purdue - . - 7/50
Atmosphere - - - - - - - - - - . - - 653
Atwood, Wallace Walter, Rollin D. ane and. Drift Phenomena in Wis-
consin - - - - - - : - - - =P aTair
Baffins Land, Evidences of Recent Elevation of the Southern Coast of. T. L.
Watson - - . - - - - - - - - - 17
Bain, H. Foster. Sketch of the Geology of Mexico - - - - = ated
Reviews: Geology of the Castle Mountain Mining District, Montana.
W. H. Weed and L. V. Pirsson . - - - - =| PHii(0)
fe Missouri Geological Survey. Vol. XI, Clay Deposits. H. A. Wheeler 399
Baltic Glacier, The Last Great. James Geikie - - - - = 25
Bannister, H. M. ‘The Drift and Geologic Time - - - - S Nisio)
Barbour, E. H. Study of the Structure and Phylogeny of Daemonelix.
(Abstract) - - - - - 223
Barlow, Alfred E., Frank D. Adams and. Origin and Reiation of the Gren-
ville wel Hastings Series in the Canadian Laurentian. (Abstract) - g2
Barton, Geo..H. Glacial Observations in Greenland. (Abstract) - - 89
Barton, Geo. H. Glacial Observations in Greenland. Review by T. C. Cham-
berlin - = - - - - - - - - - - 650
Basalt - - - = - - - - - - - - - - 255
Bascom, Florence. Ancient Volcanic Rocks of South Mountain, Pennsylvania.
Review by J. P. Iddings - - - - - = : - 213
Bauxite Deposits of Arkansas. J. C. Branner : - - 263
Bayley, W. S., C. R. Van Hise and. Preliminary Report on the arenes
Region. Review by U.S. Grant - - - - - - - 402
Beaches with Outlets and Moraines in Southeastern Michigan, Correlation of
Erie-Huron. F.B. Taylor. Review by C. H. Gordon’ - - 313
Becker, G. F. Some Queries on Rock Differentiation. Review by C. F. Tol-
man, Jr. - - - - - - - - - - 393
Bedford Odlitic Limestone of Indiana. T.C. Proaee and C. E. Siebenthal.
Review by J. C. Branner - - - - - - - - =) 5520
Bibbins Arthur, William B. Clark and. The Stratigraphy of the Potomac
Group in Maryland - . - - - : - - - - 479
BIBLIOGRAPHY :

Italian Petrological Sketches, 34; of Crystalline Schists, 293; of influ-
ence of Granitic Intrusion upon the development of Recent Elevations
in North America, Partial, 32; of the Bauxite, 285; of the Lower
Cretaceous - - - - - - - - - - - 610

864 INDEX TO VOLUME V

PAGE
BIBLIOGRAPHY: Recent Publications - - - - - 224, 419, 535, 701
Biotite-Vulsinite — - - - - - > - - < : = 250
Blatchley, W. S. Geology and Natural Resources of Indiana. Review by T.

C. Chamberlin - - - - - - - = - - - 644
Bowlder Clays of the Great Plains Marine? Are the. Geo. M. Dawson SS
Bracciano Region - - - - - - : 2 = : : 35
Branner, J. C. The Bauxite Deposits of Arkansas = = = = 2 263

Reviews: Bedford Oolitic Limestone of Indiana. T.C. Hopkins and
C. E. Siebenthal . - - - - = - - - - 529
Devonian Fauna in the Reo Maccart. F. Katser - - - SFIS)
Former Extension of the Appalachians across Mississippi and Texas.
Review by A. H. Purdue - - - - - - - - - 759
Unpublished Papers of the Geological Survey of Brazil - - 5 750
Brazil, Unpublished Papers of the Geological Survey of. Review by J. C.

Branner_ - : = = - = - = - . - 756
Brickmaking, the Science of. F. G. Harris. Review by Wm. B. Clark - - 658
Brooks, A. H., and J. E. Woiff. The Age of the White Limestone of Sussex

County, New Jersey - - - - - - - - - sez
Brooks, A. H., C. W. Hayes and. Crystalline and Metamorphic Rocks of

Northwestern Georgia. (Abstract) - - - - = : Ss 3
Brush, Geo. J. Manual of Determinative Mineralogy. Review by O. C. Far-

rington - - - - - - - - - = - = 86
Bulletins of American Paleontology, Vol. I. G.D. Harris. Review by Stuart

Weller - - - - - - - - - - : = 340%)
Bulletins of the Minnesota Academy on Natural Sciences. Vol. IV, No. 1, Pt.

I. Proceedings and Accompanying Papers. Review by T. C.

Chamberlin - - - - : - S z 2 2 = OAS
California and Lower California, The Submerged Valleys of. Geo. Davidson.

Review by W. S. Tangier Smith - - - - : - =) see
California at the Typical Locality, The Geological Relations of the Martinez

Group of. John C. Merriam - s - Z E 2 : = GH
California, The Topography of. Noah Fields Drake - - - - 563
Calvin, S. Iowa Geological Survey. Review by T.C. Oromia - - 642
Campbell, M. R. Erosion at Base Level. (Abstract) - - - - J Bap

Origin of Certain Topographic Forms - - - - = = g2e
Canada, Geological Survey of. Annual eae G. M. Dawson. Review by

T.C. Chamberlin” - = = 2 2 : : = ens
Cape of Good Hope, First Report of the Eas Commission of the Colony

of the. Review by T. C. Chamberlin - - - - 647
Carbon Dioxide” - - - - = = 3 < A % s = OR
Carboniferous and Permian Formations of Kansas and Nebraska, Comparison

of. Charles S. Prosser. Part I - - - - - - - I

Part IIL 5 - = = = Ran tests : Snae

Castle Mountain Mining District, Oh ehciey of the. W. H. Weed and L. V.
Pirsson. Review by H. F. Bain - - - - - - = 20

INDEX TO VOLUME V

Catalogue de Bibliographies Geologiques. (Editorial) T.C.C. - -
Catalogue of Tertiary Mollusca. Geo. F. Harris. Review by Wm. B. Clark -
Cerveteri Region - - - - - - - - -
Chamberlin, T. C. A Group of Bipsiieecs Beene on Climatic eee -
Glacial Studies in Greenland. X - - - - -
Method of Multiple Working Hypotheses” - - - Ss :
Supplementary Hypotheses pees the Origin of Loess of the Missis-
sippi Valley - - - - - - - - - =
Editorials: Andrée’s Expedition - - - : 2 _ Z
Catalogue des Bibliographies Geologiques - - - - =
Detroit Meeting of the American Association for the Advancement of
Sciences - - - - - - - - : - -
Lectures of Dr. Hans Reush - - - - - - : =
The Limit of Greenland Glaciation - - - - - - :
Removal of the Director of the Geological Survey of Missouri - -
Reviews: Bulletin of the Minnesota Academy of Natural Sciences
First Report of the Geological Commission of the Colony of the Cape
of Good Hope - - - - - - - - - =
Former Extension of Cornell Glacier near the Southern End of Mel-
ville Bay - - - - - - - - - - -
Geological and Natural Resources of Indiana. W. S. Blatchley
Geological Survey of Alabama. E.A. Smith. Report on the Coosa
Valley. H.McCalley - - - - - - - - -
Geological Survey of Canada. G. M. Dawson - - - - -
Glacial Lake Agassiz. Warren Upham - - - - - -
Glacial Observations in the Umanak District, Greenland. G. H.
Barton - - - - - - - - - - - -
Glaciers of North America. I. C. Russell - - - - - -
Iowa Geological Survey. S. Calvin - - - - - - -
Laws of Mines and Mining in the United States - - - -
North Carolina and Its Resources - - - - - - -
Proceedings of the Davenport Academy of Natural Sciences
Proceedings of the lowa College of Sciences’ - - - - -
Seventeenth Annual Report of the United States Geological Survey -
Stone Implements of the Potomac Chesapeake Tide Water Province.
W.H. Holmes” - - - - - - - - -
Chase, E.C. Review: Dinosaurs of North America’ - -
Ciminite : : - - - - - - - - -
Clark, William Bullock, and Arthur Bibbins. The Stratigraphy of the Poto-
mac Group in Maryland - - - - - - - - -
Clark, W. B. Cretaceous of the North Atlantic Coastal Plane. (Abstract)
Eocene Deposits of the Middle Atlantic Slope. Review by C. R.
Keyes - - . - - - - - - = =
Maryland Geological Ben Review by R. D. Salisbury - - .
Reviews: Catalogue of the Tertiary Mollusca. Geo. F. Harris -
Science of Brickmaking. G.F. Harris” - - - - - -

866 INDEX TO VOLUME V

Clay Deposits Missouri Geological Survey. Vol. XI. H. A. Wheeler. Review
by H. F. Bain - - - - - - - - - - -
Climatic Changes, A Group of Hypotheses Bearing on. T.C. Chamberlin -
Colorado, An Analcite Basalt from. Whitman Cross - - - = :
Commission of the Colony of the Cape of Good Hope, First Report of the
Geological. Review by T.C. Chamberlin - - - - -
Comparative Study of Paleontology and Phylogeny. (Studies for Students)
James Perrin Smith - - - - = : : : - =
Comparative Study of the Lower Cretaceous Formation and Fauna of the
United States. Timothy William Stanton - - - - -
Cornell Glacier near the Southern End of Melville Bay, Former Extension of.
Ralph S. Tarr. Review by T. C.C. - - - - - -
Correlation of Erie-Huron Beaches with Outlets and Moraines in Southeastern
Michigan. F.B. Taylor. Review by C. H. Gordon - - -
Correlation of the Devonian Faunas in Southern Illinois. Stuart Weller -
Cragin, W. F. Discovery of Marine Jurassic Rocks in Southwestern Texas -
Cretaceous Formation and Faunas of the United States, A Comparative Study
of the Lower. Timothy S. Stanton - - - - - - -
Cripple Creek District Colorado, Geology and Mining Industry of. Whitman
Cross, and R. A. F. Penrose, Jr. Review by Arthur Winslow - :
Cross, Whitman. An Analcite Basalt from Colorado’ - - - - -
Cross, Whitman, and R. A. F. Penrose. Geology and Mining Industry of Crip-
ple Creek District. Review by Arthur Winslow - - - -
Cryptodiscus, Hall. Stuart Weller - - - - - - - -
Crystalline Schists, Some Recent Papers on the Influence of Granite Intrusions
Upon the Development of. Review by Frank S. Adams. - - -

Daly, R. A. Studies on the So-called Porphyritic Gneiss. Part 1 - - -
Part II - - - - - - - - = = : =
Darton, N. H. Dikes in Appalachian Virginia. (Abstract) - - - -
Davenport Academy of Natural Sciences, Proceedings of the. Review by T.
C. Chamberlin - - - - - - - - -- -
Davidson, Geo. The Submerged Valleys of California and Lower California.
Review by W. 5S. T. Smith - - - - - - : -
Dawson, Geo. M. Are the Bowlder Clays of the Great Plains Marine? - -
Geological Survey of Canada. Review by T. C. Chamberlin - -
Editorial, Laurentide Glacier - - - - - - = -
Deformation of Rocks. V (Studies for Students). C. R. Van Hise - -
Delaware and Virginia, Eocene Deposits of the Middle Atlantic Slope in Mary-
land. Wm. Bullock Clark. Review by Chas. R. Keyes - - -
Devonian Faunas in Southern Illinois, Correlation of the. Stuart Weller -
Devonian Fauna of the Reo Maecurt. F. Katzer. Reviewby J. C. Branner -
Differentiation, Some Queries on. G. F. Becker. Review by C. F. Tolman, Jr.
Divides, A Note on the Migration of. W.S. Tangier Smith - - - -
Diller, J. S. Crater Lake, Oregon. (Abstract) - - - - - -
Dinosaurs of North America. Othniel Charles Marsh. Review by E. C. Chase

PAGE

INDEX TO VOLUME V

Discovery of Marine Jurassic Rocks in Southwestern Texas. F. A. Cragin -
Drake, Noah Fields. The Typography of California — - - - -
Drift and Geologic Time. H.M. Bannister - - - - - - -
Driftless Region of Wisconsin, Studies in. G. H. Squier - - - -
Drift Phenomena in the Vicinity of Devil’s Lake and Baraboo, Wisconsin.
Rollin D. Salisbury, Wallace Walter Atwood, and - - - -

Elementary Geology. Ralph S. Tarr. Review by H. B. Kiimmel - -
EDITORIALS.
Andrée’s Expedition. T.C.C. - - - - - - - -
Catalogue des Bibliographies Geologiques. T.C.C. - - - -
Detroit and Toronto Meetings. T.C.C. - - - - -
George Huntington Williams Memorial Lectures. J.P. I. - -
International Congress at St. Petersburg. J. P. I. - - - -
International Congress upon Classification. J. P.I. - - - -
Laurentide Glacier. G.M.D. - : : - - - : -
Weciiresiot Dr ans) Reusch. | di GG: - - - - -
Limit of Greenland Glaciation. T.C.C. - - - - - -
Meeting of the Geological Society of America. J. P. I. - - -
Removal of the Director of the Geological Survey of Missouri. T.C. C.
Rohn’s Collections of Rock Specimens J.P. I. - - - - -
Seventh Session of the International Congress of Geologists. J. P. I. .-
Winter Meetings of the Geological Society of America. I. C. R. -
Elevated Reef of Florida. Alexander Agassiz, with Notes on Geology of
Southern Florida. Leon S. Griswold. Review by J. Edmund Wood-
man - - - - - - - - - - - - -
Elevation of the Southern Coast of Baffin Land, Evidences of Recent. Thomas
L. Watson - - - - - - - - - - -
Eocene Deposits of the Middle Atlantic Slope in Maryland, Delaware, and
Virginia. Wm. Bullock Clark. Review by Charles R. Keyes - -
Eruptive Rocks of Mexico. O.C. Farrington - - - . - -

Fairbanks, Harold W. The Geology of San Francisco Peninsula - - -
Fairchild, H. L. Shore Lines of Lake Warren and of a Lower Water Level in
Western New York. (Abstract) - - . - - - -
Farrington, O. C. Average Specific Gravity of Meteorites - - - -
The Eruptive Rocks of Mexico - - = - - - -
Review: Manual of Determinative Mineralogy, with an Introduction on
Blowpipe Analysis. Geo. J. Brush - - - - - - -
Faults, The Measurement of. J. Edward Spurr - -
Florida. The Elevated Reef of Alexander Agassiz, with Notes on the Gerace
of Southern Florida. Leon S, Griswold. Review by J. E. Woodman
Forestian Stage, Lower - - - - - - - - - - -
Upper - - - . - - - . . - - - -
Former Extension of Cornell Glacier near the Southern End of Melville Bay.
R.S. Tarr. Review by T C. Chamberlin - : - -

868 INDEX TO VOLUME V

Former Extension of the Appalachian across Mississippi, Louisiana, and Texas.
J. C. Branner. Reviewed by A. H. Purdue. - - = - -

Fossil, Lists of pages. 2, 6, 7, 9, I5I, 153, 155, 157; 158, 159, 160, 161, 163,
164, 165, 166, 167, 261, 262, 589, 596, 597, 598, 603, 606, 617, 618,
626, 627, 628, 629, 630, 631, 632, 769, 770, 772, 813, 816.

Geikie’s Classification of the North European Glacial Deposits. K. Keilhack
Geikie, James. The Last Great Baltic Glacier - - - - - -
Geikie, Sir Archibald. Ancient Volcanoes of Great Britain. Review by J. B.
Iddings - - - - - - - : 2 : = :
Geography and Geology. Israel €. Russel. Review by T.C. Chamberlin -
Geological Commission of the Colony of the Cape of Good Hope. First
Report of the. Review by T. C. Chamberlin - - - - -
Geological Relations of the Martinez Group of California at the Typical
Locality. John C. Merriam - = - - - - - -
Geological Society of America, Meeting of. Editorial. J. P.I. - - -
Geological Society of America, Meetings of. Editorial. T.C. C. - -
Geological Society of America, Papers read before. (See Abstracts)
Geological Survey, lowa. S. Calvin. Review by T. C. Chamberlin - -
Geological Survey of Alabama. E. A. Smith. Report on the Coosa Valley.
H. McCally. Review by T. C. Chamberlin - - - - -
Geological Survey of Canada, Annual Report. S.M. Dawson. Review by T.
C. Chamberlin - - - - - - - - - - -
Geology and Natural Resources of Indiana, Twenty-first Annual Report. W.
S. Blatchley. Review by T. C. Chamberlin — - - - - -
Geology, An Introduction to. W.B. Scott. Review by R. D. Salisbury -
Geology, Elementary. R.S. Tarr. Review by H.B. Kimmel - - -
Geology of Mexico, a Sketch of. H. Foster Bain - - - - - -
Geology of San Francisco Peninsula. Andrew C. Lawson - - - -
Geology of San Francisco Peninsula. Harold W. Fairbanks - - -
Geology of Santa Catalina Island. William Sidney Tangier Smith. Review
by F. L. Ransome - - - - - - -
Geology on Southwestern New England, Note on. Wm. H. Hobbs - -
Gilbert, G. K. Old Tracks of Erian Drainage in Western New York.
(Abstract) - : = : - = : = z
Glacial Deposits, Geikie’s Classification of the North European. K. Keilhack
Glacial Lake Agassiz. Warren Upham. Review by T. C. Chamberlin -
Glacial Observations in the Umanak District Greenland. D. H. Barton.
Review by T. C. Chamberlin — - - - - : : - =
Glacial Studies in Greenland. X. T.C.Chamberlin - - - = =
Glacier Bay and its Glaciers. Harry Fielding Reid. Review by I. C. Russell
Glaciers of North America. A Reading Lesson for Students in Geography and
Geology. Israel C. Russell — - : = = 2 = 2
Glaciers of North America. I. C. Russell. Review by T. C. Chamberlin -
Glaciers, Variations of. Harry Fielding Reid EHS : 2 s =
Glacier, the Last Great Baltic. James Geikie - - - : = E

PAGE

113
325

531
302

647

767

325

INDEX TO VOLUME V

Gordon-C. H. Review: Correlation of Erie-Huron Beaches with Outlets and
Moraines in Southeastern Michigan. F. b. Taylor - - - -
Granitic Intrusions upon the Development of Crystalline Schists ; Some Recent
Papers on the Influence of. Review by Frank D. Adams - - -
Grant, U.S. Review: Preliminary Report on the Marquette District. C. R.
Van Hise and W.S. Bayley. Witha Chapter on the ee sags
H. 1. Smyth = - - - - - - .
Greenland, Glacial Studies in. X. T.C.Chamberlin - - - - -
Greenland, Glacial Observation on the Umanak District. G. H. Barton.
Review by T. C. Chamberlin - - - - - - - -
Greenland Glaciation, Limit of. Editorial T.C.C. - - - - -
Grimsley,G.P. Origin and Age of the Gypsum Deposits of Kansas. (Abstract)

Hall C. W. Bulletin Minnesota Academy Sciences. Review by T. C. Cham-
berlin - . - - - - - - - - - -
Harris, G. D. Bulletin of American Paleontology. Review by Stuart Weller
Harris, G. K. Catalogue of Tertiary Mollusca. Review by W. B. Clark -
Science of Brickmaking. Review by W. B. Clark - - -
Haworth, E. University Geological Survey of Kansas. Review by Stuart
Weller - - - - - - - - - - - -
Hayes, C. W. Solution of Silica - - - - - - < - -
Hayes, C. W., A. H. Brooks and. Crystalline and Metamorphic Rocks of
Northwestern Georgia - - - . - etc - -
Helvetian Stage - - - - - - - - - - - -
Hershey, Oscar H. Mode of Formation of Till as Illustrated by the Kansas
Drift of Northern Illinois - - - - - - - - :
Hobbs, William H. Note on the Geology of Southwestern New England -
Holmes, W. H. Stone Implements of the Potomac, bss ae Tide-water
Province. Review by T. C. Chamberlin - - - -
Hopkins, T.C. and C. E. Siebenthal. The Bedford Oolitic Limestone of Indi-
ana. Review by J. C. Branner = = - - - - =
Hypotheses Bearing on Climate Changes, a Group of. T.C. Chamberlin — -

IppDINGS — EDITORIALS:
Meeting of the Geological Society of America - - - -
International Congress at St. Petersburg - - - -
International Congress upon Classification - - : = -
Rohn’s Collections of Rock Specimens - - - - : -
Seventh Session of the International Congress of Geologists - - -
The George Huntington Williams Memorial Lectures - - - -
Reviews: Ancient Volcanoes of Great Britain. Archibald Geike
Ancient Volcanic Rocks of South Montana, Pennsylvania. Florence
Bascom - - - - - - - - - - = -
Illinois, Correlation of the Devonian Faunas in Southern. Stuart Weller -
Illinois, Mode of Formation of Till, as Illustrated by the Kansas Drift of
Northern. Oscar H. Hershey - - - - - - - -

PAGE

648
309
853
859

400
819

319
114

50
175

649

529
653

77
290
848
195
752
391
531

213
625

50

870 INDEX TO VOLUME V

Indiana, Geology and Natural Resources Twenty-first Annual Report. W.S.
Blatchley. Review by T. C. Chamberlin - - - - - -
Iowa Geological Survey a on Lead, Zinc, Artesian Wells, etc. S. Cal-
vin. Review by T. C. Chamberlin - - - - - -
Introduction te Geology. W. a Scott. Review by R. D. cane - -
Italian Petrological Sketches. III. The Bracciano Cerverteri and Tolfa
Regions. Henry S. Washington - - - - -
Italian Petrological Studies. IV. The Rocca Monfina Region. Henry S. Wash-
ington - - - - - - - - - - - -
Italian Petrological Sketches. V. Summary and Conclusion. Henry S. Wash-
ington - - - - - - - - - - - -
Iwasaki, C. Andeniorite in Japan - = = : - = = - =
James, Joseph, Notes on the Potsdam and Lower Magnesian Formations of
Wisconsin and Minnesota. (Abstract) - - - - - :
Japan, Andendiorite in. Iwasaki - = S = : - = 2 =
Jurassic Rocks in Southwestern Texas, Discovery of. W. F. Cragin . -
Kansas and Nebraska, Comparison of the Carboniferous and Permian Forma-
tions of. Charles S. Prosser. Pt. I - - - - - -
1X6 LIL - - - - - - - - - - - =
Kansas, University Geological Survey of. E. Haworth. Review by Stuart
Weller - . - - - - - - - - - -
Katzer, F. Devonian Fauna of the Reo Maecurti - - - - - =
Keilhack, K. Professor Geikie’s Classification of the North European Glacial
Deposits - - - - = : = 2 = : = -
Kemp, J. F. The Leucite Hills of Wyoming. (Abstract) - Sails -
The Pre-Cambrian Topography of the Eastern Adirondacks. (Abstract) -
Keyes, Charles R. Review: Eocene Deposits of the Middle Atlantic Slope in
Maryland, Delaware and Virginia - - - - - -
Physical Nature of the Problem of General Geological Correlation -
Knowlton, F. H., T. W. Stanton and. Stratigraphy and Paleontology of the
Laramie and Related Formations in Wyoming. (Abstract) - -
Kiimmel, Henry B. The Newark System of New Jersey - - - -
Kiimmel, H. B. Elementary Geology. Review by R.S. Tarr - - =
Lane, Alfred C. The Grain of Rocks. (Abstract) - - - - :
Last Great Baltic Glacier. James Geikie = = 2 = = = =
Laurentide Glacier. Geo. M. Dawson - - - - - - = -
Laws of Mines and Mining in the United States. Review by T. C. Cham-
berlin - 2. : “ 2 2 z 3 A 3
Meucitite; ja - - - - - - - - - = 41, 245,
Leverett, Frank. Water Resources of Illinois. Review by W. H. Norton -
Report of the United States Deep Waterways Commission - - =

Loess of the Mississippi Valley, ea Hypotheses Respecting the.
T.C. Chamberlin — - : : ¢ 2 2 5 Z iH

PAGE

644

648
298

113

310
110

102

541
817

222
325
78

858
369
206

758

795

INDEX TO VOLUME V

Marquette Iron Bearing District of Michigan, Preliminary Report on. C.R.
Van Hise and W. S. Bayley. With a Chapter on the Republic

Trough. H.L. Smyth. Review by U.S. Grant - - - -

Marsh, O. C. Dinosaurs of North America. Review by E. C. Chase - -
Martinez Group of California at the Typical Locality, the Geological Relations
of. John C. Merriam = : - = - : = = :
Maryland, Delaware and Virginia, Eocene Deposits of the Middle Atlantic
Slopes in. Wm. B. Clark. Review by Charles R. Keyes - -
Maryland Geological Survey. Vol. I. Review by R. D. Salisbury - -
McCally,H. Tennessee Valley.Regions. Review by Stuart Weller - -
Coosa Valley Regions. Review by T. C. Chamberlin - - - -
Measurements of Faults. J. E. Spurr - - - - . - .
Mechlenbergian Stage - = - - - - - - : -
Medusae in the Niagara Limestone of Illinois, On the Presence of Problematic.
Stuart Weller - - - - - - - - - -
Merriam, John C. The Geological Relation of the Martinez Cra of Califor-
nia at the Typical Locality - - - - - - - -

Merrill, George P. Notes on Rock Weathering. (Abstract) - - - -
Meteorites, Average Specific Gravity of. Oliver C. Farrington - : -
Mexico, A Sketch of the Geology of. H. Foster Bain - - - - -
The Eruptive Rocks of. O. C. Farrington - - - - -
Michigan, Preliminary Report on the Iron-bearing District of. C.R. Van Hise
and W. S. Bayley, with a Chapter on the Republic ee Hi. L.

Smyth. Review by U. S. Grant - - - - - -
Migration of Divides, A Note on the. W.S. Tangier Smith - - -
Mineralogy, with an Introduction on Blowpipe Analysis. Manual of Deter-
minative. Geo. I. Brush. Review by O. C. Farrington - - -
Minnnesota Academy of Natural Sciences, Bulletin of. C.W. Hall. Review
by T. C. Chamberlin - - - - - - - - -

Final Report on the Geology of; Palzontology. Review by Stuart
Weller’ - - - - - - - - - - - .
Missouri Geological Survey, Vol. XI; sag Deposits. H.A. Wheeler. Review
by H. Foster Bain - - - - - - - - -
Molecular Velocities - - : - - - - - - : -
Moraines of Recession and their Significance in Glacial Theory. Frank
Bursley Taylor - - - - - - - - - -
Multiple Working Hypotheses, The Method of. T. C. Chamberlin - -

Nebraska, Comparison of the Carboniferous and Permian Formations of Kan-
sas and. Charles S. Prosser. Pt. I, - - - = = -
tJ - - - : - - 5 s 3 :

Nebular Hypothesis : - - - = - = - = ‘ :

Neudeckian Stage - - - - - = - - - : - :

Newark System of New Jersey Henry b. Kiimmel - - - - :

New England, Note on the Geology of Southwestern. William H.
Hobbs - = - “ - = : 5 a 4 :

872 INDEX TO VOLUME V

New Hampshire, Studies on the So-called Porphyritic Gneiss of. R.A. Daly.
Bt - - - : - - - - - - -
Pt. Il - - - - - - - - - - - -
New Jersey, The Newark System of. Henry B. Kiimmel - - - -
Niagara Limestone of Northern Illinois, On the Presence of Problematic
Medusae in the. Stuart Weller - - - - - -
North Carolina and its Resources. Review by T. C. Chamberlin - - -
Norton, W. H. Review: Water Resources of Illinois. Frank Leverett -

Oolitic Limestone of Indiana, The Bedford. T.C. Hopkins and C. E. Sieben-
thal. Review by J. C. Branner - - - : E : :

Paleontology and Phylogeny, Comparative Study of. J. P. Smith - -
Bulletin American, Vol. I. G.D. Harris. Review by Stuart Weller -

Final Report on the Geology of Minnesota; Vol. III, Pt. II]. Review

by Stuart Weller . - - - - - - - -

Parabolic Velocities - - - - 659, 660,

Penrose, R. A. F., Whitman Cross and. seesiote and Mining Industry of the
Cripple Cieck District. Review by Arthur Winslow - -
Permian Formations of Kansas and, Nebraska, Comparison of the Carbonif-
erous and. Pt.I - - - - - - = - - .
Pt. I - - - - - - - - - - - -
Phylogeny, Comparative Study of Palzontology and. J. P. Smith - -
Pirsson, L. V., W. H. Weed and, Geology of the Castle Mountain Mining
District. Review by H. F. Bain - - - - - - -
Polandian Stage - - - - - - - - - -
Porphyritic Gneiss of New Heneneee Studies on the So-called. R.A. pee
Pt. 1 - - - - - - - - - - -
Pt. I] - - - - - - - - - -
Post-Pleistocene Elevation of the Inyo Range and the Lake Beds of Waucobi
Embayment, Inyo County, California. Charles D. Walcott - -
Potomac Group in Maryland, the Stratigraphy of the. W. B. Clark and
Arthur Bibbins - - - > : - . - - -
Proceedings of the Davenport Academy of Natural Sciences. Review by T.
C. Chamberlin - - - - - - - - - - -
Proceedings of the Iowa Academy of Sciences. Review by T. C.
Chamberlin - - - - - - - - - - -
Prosser, Charles S. Comparison of the Carboniferous and Permian Formations
of Kansas and Nebraska, Pt. I - - - = - - -
IPAS IL - - - : - - = - : : = -
Purdue, A. E. Review: The Former Extension of the Appalachians Across
Mississippi, Louisiana and Texas. J.C. Branner - = = -

Ransome, F. L. Review: The Geology of Santa Catalina Island. Wm. Sid-
ney Tangier Smith - - 2 - E : Zs 2 :

PAGE

208

Recent Publications - = - - - - - - 224, 419, 535, 761

WNDEX TO VOLUME V

Reef of Florida, The Elevated. Alexander Agassiz. With Notes on the
Geology of Southern Florida, by Leon S. Griswold. Review by J.
Edmund Woodman - - - - - = - - -

Report of the United States Deep Waterways Gommmecion Review by Frank
Leverett - - - - - - - - - - - -

Reid, Harry Fielding. Variations of Glaciers. II - - - -

Glacier Bay and its Glaciers. (Review by Israel C. Russell) - -
Principal Features of the Geology of Southwestern Washington.
(Abstract) - - - - - - - - - - -

REVIEWS:
Ancient Volcanic Rocks of South Mountain, Pennsylvania. Florence
Bascom. (J. P. Iddings) - - 2 - - - - -
Ancient Volcanoes of Great Britain. Sir Archibald Geike. (J. P.
Iddings) - - - - - - - . = - - -
An Introduction to Geology. W.B Scott. (R. D.S.) - - -
Bedford Odlitic Limestone of Indiana. T. C. Hopkins and C. E. Sie-
benthal. (J. C. Branner) - - - - - - -
Bulletins of American Paleontology. G. F. Harris. (Stuart Weller)
Bulletin of the Minnesota Academy of Natural Sciences, Proceedings
and Accompanying Papers, 1892-1894. C. W. Hall. (T.C.C.) -
Catalogue of the Tertiary Mollusca. G. F. Harris. (William B.
Clark) - - - - - - - - - 5 - -
Correlation of Erie-Huron Beaches, with Outlets and Moraines in South-
eastern Michigan. F. B. Taylor. (C.H. Gordon) - - : -
Devonian Fauna of the Reo Maecurt. F. Kaetzer. (J.C. Branner) -
Dinosaurs of North America. Othniel Clark Marsh. (E. C. C.) -
Elementary Geology. Ralph S. Tarr. (Henry B. Kiimmel) - -
Elevated Reef of Florida. Alexander Agassiz. (J. Edmund Woodman)
Eocene Deposits of the Middle Atlantic Slope in Maryland, Delaware
and Virginia. Wm. B. Clark. (Charles R. Keyes) - - - -
Final Report on the Geology of Minnesota, Palzontology. (Stuart
Weller) - - - - - - - - - - - -
First Report of the Geological Commission of the Colony of the Cape
Good Hope, (Gee) = - - : - - - - -
Former Extension of the Appalachians Across Mississippi, Louisiana,
and Texas. J.C. Branner. (A. H. Purdue) - - - - =
Former Extension of Cornell Glacier near the Southern End of Mel-
ville Bay. Ralph Ss: Darr. (T. €. C:) - - - - - -
Geology and Mining Industry of the Cripple Creek District, Colorado,
Whitman Cross and R. A. F. Penrose, Jr. (Arthur Winslow) - -
Geology and Natural Resources of Indiana, Twenty-First Annual Report.
Vie So lBibiealley, (1s (Ca (Gy) = - - - - - - -
Geology of the Castle Mountain Mining District, Montana. W.H. Weed
and L. V. Pirsson. (H. F. Bain) - - - - - -
Geology of the Santa Catalina Island. Wm. S. T. Smith. (F. L.
Ransome) - - = - - - - - - - -

873

PAGE

312

758
378
203

874 INDEX TO VOLUME V

PAGE
REVIEWS :
Geological Survey of Alabama, Report on the Valley Regions. E. A.
Smith, Part II. On the Coosa Valley, Henry McCalley. (T.C.C.) - 646
Geological Survey of Canada, Annual Report, Vol VIII, 1895. G. M.
Dawsonea GC Cs) - - - - : - - - - 641
Glacial Lake Agassiz. Warren Upham (T. C. C.) - - - - 851
Glacial Observations in the Umanak District, Greenland. George
lal, Baro, (ito C, G)) - - - - - - - - 650

Glacier Bay and its Glaciers. Harry Fielding Reid. (Israel C. Russell) 203
Glaciers of North America; a Reading Lesson for Students in Geog-

raphy and Geology. Israel C. Russell. (T.C. C.) : = - 302
Iowa Geological Survey, Vol. VI, Report on Lead, Zinc, Artesian Wells,

etcey, poamuell Calvin (as) - - - - - - 5 Ow
Law of Mines and Mining in the United States. (T.C. C.) - - 858
Manual of Determinative Mineralogy, with an Introduction on Blowpipe

Analysis. George J. Brush. (O. C. Farrington) - - - - 86
Maryland Geological Survey. W. B. Clark. (R. D.S.) - - - 760
Missouri Geological Survey. H. A. Wheeler. (H. Foster Bain) - - 399
North Carolina and Its Resources. (T.C.C.) - - - - - 648

Preliminary Report on the Marquette Iron-Bearing District of Michi-
gan. Charles Richard Van Hise and William Shurley Bayley. With
a Chapter on the Republic Trough by Henry Lloyd Smyth. (U.S.

Grant) - - - - - - - : . - - - 402
Proceedings of the Davenport Academy of Sciences. (T. C. C.) - 649
Proceedings of the lowa Academy of Sciences, 1896. (T.C. C.) - 648

Report of the United States Deep Waterways Commission. (F. Leverett) 758
Report on the Valley Regions of Alabama (Paleozoic Strata). Part I.
On the Tennessee Valley Regions, Henry McCalley. (Stuart Weller) 307

Science of Brickmaking. George F. Harris. (Wm. B. Clark) — - - 858
Seventeenth Annual Report of the U.S. Geological Survey. Charles
ID Wiallcotts ile aCs) = - - - - - - - - 651

Some Queries on Rock Differentiation. G.F. Becker. (C. F. Tolman, Jr.) 393
Some Recent Papers on the Influence of Granitic Intrusions upon the
Development of Crystalline Schists. (Frank D. Adams) - - = AOR
Stone Implements of the Potomac-Chesapeake Tidewater Province.
W. H. Holmes. From the Fifteenth Annual Report of the Bureau of

Bthnolo siya Cy@.)-.- - - = > - - - - 649
Submerged Valleys of the Coast of California, U. S. A., and of Lower

California, Mexico. George Davidson. (W.S. Tangier Smith) = GRR
Transactions of the American Institute of Mining Engineers. (C. F.

Tolman, Jr.) - : 2 : 2 E : c : = = - 52
University Geological Survey of Kansas. Erasmus Haworth and Assist-

ants. (S. W.) - - - - = - - = - - - 400
Unpublished Papers of the Geological Survey of Brazil. (J.C. Branner) 756
Water Resources of Illinois. Frank Leverett. (W.H. Norton) - - 206

Rocca Monfina Region - - - - - - - - = Bait

INDEX FO VOLUME V

Russell, I. C. Glaciers of North America. Review by T. C. Chamberlin -
Notes on the “ Plasticity of Ice.” (Abstract) - - = - -
Winter Meeting of the Geological Society of America. (Editorial) — -
Review: Glacier Bay and its Glaciers. Harry Fielding Reid. - -
Principal Features of the Geology of Southeastern Washington - -

Salisbury, Rollin D., Wallace Walter Atwood and. Drift Phenomena in Wis-
consin~ - - - - - - -
Salisbury, Rollin D. Reviews: An Introduction to Geeleay: W. Bb. Scott
Maryland Geological Survey - - - - - - - 2
San Francisco Peninsula, The Geology of. Andrew C. Lawson - : =
San Francisco Peninsula, The Geology of. Harold W. Fairbanks -
Saxonian Stage - - - - - - - - - = : :
Scanian Stage - - - - - - - : - - - :
Science of Brickmaking. George F. Harris. Review by Wm. B. Clark =
Scott, W. B. Introduction to Geology. Review by R. D. Salisbury - -
Seventeenth Annual Report of the United States Geological Survey. Review
by T. C. Chamberlin - : - - - - - - =
Siebenthal, C. E., T. C. Hopkins and. The Bedford Oolitic Limestone of
Indiana. Review by J. C. Branner - = - = = Z
Smith, James Perrin. Comparative Study of punting and Phylogeny -
Smith, William Sidney Tangier. A note on the Migration of Divides
Geology of the Santa Catalina Island. Review by F. L. Ransome
Review: Submerged Valleys of the Coast of California and Lower Cali-
fornia, G. W. Davidson - - - - - - = - 2
Specific Gravity of Meteorites, Average. Oliver C. Farrington — - = E
Spurr, J. Edward. The Measurement of Faults = = 2 = 5 -
Squier, G. H. Studies in the Driftless Region of Wisconsin - z -
Stanton, Timothy William. A Comparative Study of the Lower Cretaceous
Formations and Faunas of the United States” - - : s i
Stanton, T. W., F. H. Knowlton and. Stratigraphy and Paleontology of the
Laramie and Related Formations in Wyoming. (Abstract) - =
Stone Implements of the Potomac Chesapeake Tidewater Province. W. H.
Holmes. Review by T. C. Chamberlin -'— - - - - 2
Stratigraphy of the Potomac ee in Maryland. Wm. B. Clark and Arthur
Bibbins © - - = = = = = = - - :
Studies in the Driftless Region of Wisconsin. G. H. Squier = = :
STUDIES FOR STUDENTS:
Comparative Study of Paleontology and Phylogeny. James Perrin Smith
Deformation of Rocks. V. C. R. Van Hise - - = =
Method of Multiple Working Hypotheses. T.C. Chamberlin - 2
Studies on the So-called Porphyritic Gneiss of New Hampshire. R. A. Daly.
Part) 3)- . - - - - - - - - - =
Part II - - - - - - - - - - - -
Submerged Valleys of the Coast of California and Lower California. George
Davidson. Review by W.S.T.Smith = - - - - 2 "

875

PAGE
302
103
194
203
107

131
398
760

73

63
II4
18113}
858
398
651
529
507

809
208

533
126

723
825
579
102

649

479
825

507
178
837

694
776

533

876 INDEX TO VOLUME V

Supplementary Hypotheses Respecting the Origin of the Loess of the Missis-
sippi Valley. T.C. Chamberlin - - - - - - -
SURVEYS :
Geological Survey of Iowa, Vol. VI, Report on Lead, Zinc, Artesian
Wells, etc. Samuel Calvin. Review by T. C. Chamberlin - -
Geological Survey of Alabama. E.A. Smith. Report on the Coosa
Valley H. McCauley. Review by T. C. Chamberlin . - -
Geological Survey of Canada, Annual Report. Review by T. C. Cham-
berlin - 2 2 - - = - - - = - -
Geology and Natural Resources of Indiana. Twenty-First Annual Report.
W.S. Blatchley. Review by T. C. C. - - - - - -
Maryland Geological Survey. Review by R. D. Salisbury - - -
Missouri Geological Survey, Vol. XI, Clay Deposits. HH. A. Wheeler.
Review by H. Foster Bain - - - - - - - -
United States Geological Survey. Review by T. C. Chamberlin - -
University Geological Survey of Kansas. E. Haworth. Review by S.Weller

Tarr, R.S. Cornell Glacier, Greenland. (Abstract) = - - - - -
Tarr, R.S. Elementary Geology. Review by H. B. Kiimmel - - -
Former Extension of the Cornell Glacier. Review by T. C. Chamberlin
Taylor, F. B. Correlation of Erie-Huron Beaches. Review by C. H. Gordon
Moraines of Recession and their Significance in Glacial Theory - -
Mattawa River the Outlet of the Nipissing Great Lakes. (Abstract) -
Tennessee Valley Regions, Report on the Valley Regions of Alabama, Part I

onthe. Henry McCalley. Review by Stuart Weller - - 25

Tertiary Mollusca, Catalogue of the. G.F. Harris. Review by W. B. Clark
Texas, Discovery of Marine Jurassic Rocks in Southwestern. F. W. Cragin -
Till as Illustrated by the Kansas Drift of Northern Illinois Mode of Forma-
tion of. Oscar H. Hershey - - - : - 2 Z : 3
Tolfa Region - - = : : : - 2 ‘| A 2 :
Tolman, Cyrus F. Jr. Reviews. Some Queries on Rock Differentiation. G. F.
Becker : - - = : 2 : Z : z g
Transactions of the American Institute of Mining Engineers” - - -
Topography of California. Noah Fields Drake - - : - 2 2
Toscanite - - - 2 - : - Z : :
Trachydolorites — - - - - - : 2 = : Z 2
Trachyte - - - = 3 = : : i u 2 s ‘
Transactions of the American Institute of Mining Engineers, Review of, by C.
F. Tolman, Jr. - - : - 2 E : S 2 S :
Turbarian, Lower - - : 2 2 zl 2 2 ‘ c :
Turbarian, Upper - - - - - - = :
Turner, H. W. Work of the United States Geological Survey in the Sierra
Nevada : = 5 = e cl 2 : i | a

Umanak District, Greenland, Glacial Observations in. Geo. H. Barton.
Review by T. C. Chamberlin - - - - - - - e

375

PAGE

795

642
646
641

644
760

399
651
400

95
317
303
313
421
220

307
863
813

50
47

393
854
563
360
350
203

854
115
116

105

650

INDEX TO VOLUME V 877

PAGE
United States Geological Survey —Seventeenth Annual Report. Review by
T.C. Chamberlin - . - - - - - - - ~ 651
University Geological Survey of Kansas. Erasmus Haworth, Vol. II]. Review
by Stewart Weller - - - - - - - - - - 400
Unpublished Papers of the Geological Survey of Brazil. Review by J. C.
Branner - - - - - - = - - 756
Upham, Warren. Glacial Lake Agassiz. Review Ee T. C. Chamberlin Sy) els
Modified Drift inSt. Paul, Minnesota. (Abstract) - - - =I HT
Valley Regions of Alabama, Report on, Pt. I, On the Tennessee Regions.
Henry McCalley. Review by Stuart Weller - - - - - 307
Van Hise, C. R.and W.S. Bayley. Preliminary Beet on Marquette District.
Review by U.S. Grant - - - - - - - 402
Van Hise, C.R. Deformation of Rocks - - - - - - - 178
Variations of Glaciers. Harry Fielding Reid. II. = - - 378
Virginia — Eocene Deposits of the Middle Atlantic Slope in Maryland: Dela-
ware, and Virginia. Wm. Bullock Clark. Review by Charles R.
Keyes - - - - - - - - - - - =| 200
Volcanoes of Great Britain, The Ancient. Archibald Geikie. Review by J. P.
Iddings - = 2 = = - : e 5 3 = 5 531
Vulsinite - - - - - : = : 2 2 = E - 356
Wabaunsee Formation - - - - 10, 148, 154

Walcott, Charles D. The Post-Pleistocene Elevation of the Tae Range and
the Lake Beds of the Waucobi Embayment, Inyo County, California 340
Seventeenth Annual Report of the United States Geological Survey.

Review by T. C. Chamberlin - - = - - - - - 651
Washington, Henry S. Italian aad Sketches III, The Bracciano,
Cerveteri, and Tolfa Regions - - = = 2 - 34
Italian Petrological Studies, 1V— The Rocca Manfina Region - = Bilin
Italian Petrological Sketches V — Summary and Conclusions - - 349
Water Resources of Illinois. Frank Leverett. Review by W. H. Norton - 208
Watson Thomas L. Evidences of Recent Elevation of the Southern Coast of
Baffin’s Land - - - - - - - - - - - 17
Waucobi Embayment, Inyo County, California — The Post-Pleistocene Eleva-
tion of the Inyo Range and the Lake Beds. Charles D. Walcott - 340
Weller, Stuart. Correlation of the Devonian Faunas in Southern Illinois - 625
Cryptodiscus, Hall - - - - - - : - - - 803
On the Presence of Problematic Fossil Medusz in the Niagara Lime-
stone of Northern Illinois - - - - - - - = AA
Reviews: Bulletins of American Paleontology, Vol. I. G.D.Harris - 309
Final Report on the ee of Minnesota — Paleontology, Vol. III,
Parti) - - - - - - - - - - 308
Report on the Valley Region of Alabama (Paleozoic Strata), Part I, On
the Tennessee Valley Regions. Henry McCalley - - - =) 307

University Geological Survey of Kansas. E. Haworth - - - 400

$78 INDEX TO VOLUME V

Weed, W. H. and L. V. Pirsson, Geology of Castle Mountain Mining Dis-
trict, Montana. Review by H. Foster Bain — - - - - -
Wheeler, H. A. Missouri Geological Survey. Review by H. Foster Bain -
White, David. Age of the Iowa Coals of Henry County, Missouri. (Abstract)
White, I. C. Complete Oil-Well Record in the McDonald Coal Fields.
(Abstract) - - - - - - - =

Willis, Bailey. Preliminary Note on the Pleistocene noes of peeet Sound.
(Abstract) - - - - : - - - - -
Winslow, Arthur. Review. eine and Mining Industry of the Cripple
Creek District, Colorado. Whitman Cross and R. A. F. Penrose, Jr.
Wisconsin, Studies in the Driftless Region of. G. H.Squier - - -
Wolff, J. E., and A. H. Brooks. Age of the White Limestone of Sussex
County, New Jersey. (Abstract) - - - - - -
Woodman, J. E. Review. The Elevated Reef of Florida, Alexander we
With Notes on the Geology of Southern Florida. Leon S. Griswold
Woodworth, J. B. Homology of Joimts and Artificial Fractures. (Abstract)
Unconformities in Martha’s Vineyard and Block Island (Abstract) -

j

PAGE

210
399
218
103

99

197
824

322
312

97
96

My
a1.
had 7 i)
figt ne baa

I oR 4 me

= , #* ¥ ;

pk A
eh A eae

Sy,
aa
tee >,
so)

.
es
Fee :
ie

¥a
iPad.
in

ae) Cy.

ce

peal =|
Sr rret

‘ i

Hage

fetta
aS (ore

a
bes
ig Aa f f
HST,

a

pA

EAro
aS
Haat

Ft

Chae
Gt

Ho
‘ Nee

acd

il

NES
rit “et
cei)
SS
ioe ro
geo
—

Ei
=

on

ee
ea
arg grab
Esa
: ey 2
ery
cane
ety a

eat
KE

Ee
aes
[at
BON gor ny
ay

fi

4
eee

ra

os

ff

|

eo

Niet

te ys 44 fyi ; ,
Wha inane scene peasy f rufa deni i ye
{ovepeaet { 4 yi ae ! { !
Mite nee) HsSens j
HOt Ra ei TR a Mae f Pa es 4!
ULE i) f jek ne { aay Weg yarey
Atha tard ( ny f i i He / i t TESTE es ha Pa . { 136
ei AV faa e bye Ailes f ey i it i j :
iv Raby eye Nea Mise ; HOt nai ; Ri : b HIRO Aaa MT k A) {
j ' i fire iy AE BEOD My (it ! i i f ' i ft
: iN Picea { fis phiies ney { f arth
rit Hay RAE stl vanitg { He { ' if } Bai
{ Pie 4 j iy h p ;
stat
SALES 2
Wey yedal a Balt 1 Hala HF Lai { ae ’ Mu
Lana ey rere iinves t q : j }
SALAM SN Aah 4 *
iiphial i \ y ! { i

SMITHSONIAN INSTITUTION LIBRARIES

3 9088 01366 9890

‘ f VAs tat }
i “ WA et
i x ; (
\ \ tir ‘ i
OY i} HK \
{
{ \ i oh i