Transactions of the Edinburgh Geological Society

Edinburgh Geological Society

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TRANSACTIONS
^wfcgial ^0aetj.^bintergl
VOL. III. PART I.
EDINBUEGH:
^rinlib for iht %atui\i^
BY COMPANY.NEIT^L AND
1877.
Registered in terms the Act 5 and 6 Vict. cap. 45.of
All rights reserved to theEdinburgh Geological SocietyvndT the in-oi-isions of the said Act.LIST OF OFFICE-BEARERS
OK THE
EDINBURGH GEOLOGICAL SOCIETY
FOE SESSION 1876-77,
BEING THE FORTY-THIRD.
^Satron.
His Grace the Duke hf Akgyll, K.T., D.C'.L., F.R.S.
{President.
David Milne-Home of Wedderburn and Milnegraden, LL.D., C'.R.S.E., F.G.S.,
Chairman of Council of the Meteorological Society of Scotland.
'F(ce=13rfsiBcnts.
.LiiiES Brtce, M.A., LL.D., r-.R.S.E., F.G.S.
•Tames Mei.\tn', Bonnington, President of the Scottish Chamber of Agriculture.
Ilonorarp 5ccrctarn.
Halph Richardson, W.S., F.R.S.E., 35 Castle Street, Edinburgh; and
Newpark House, Midcalder.
STrfasurcr.
George Lyon, George Heriot's Hospital Chambers, 7 Royal E.\change, Edinburgh.
librarian. Curator of JHustum.
R. D. Keb. John Henderson.
I
ffiouncdiora.
Andrew Fleming, M.D., C'.R.S.E., Dejmty Surgeon-General H.M.I.A.
John Buchanan, C.E. I Alexander Somervail.
Andrew Taylor, F.C.S., Mineral Surveyor, Etlinburgh.
James Linn, of H.M. Geological Survey of Scotland.
Thomas W. Kilgocr, Royal Bank of Scotland.
COMMITTEES.STANDING
IZibrarp Committee
The President, Librarian, Honorary Secretary, Treasurer, and
Messrs James M'Intosh, Bookseller, and James Mklvin.
jfJtuscum Commhtfc.
W. T.The President, Curator, Honorary Secretary, Treasurer, and Dr
Black, Surgeon-Major, and Ale.xander Somervail.
^9ublt8f)ing CTommftuc.
The President, Honorary Secretary, Treasurer, .ind Messrs John Henderson,
Publisher, and AndrewDuncan Maclachlan, Taylor.
1Coti)(ans ants jPifc ^Pali'ontological Committer.
Alexander Somervail, Convener; Dr .James Bryce, and Messrs John Henderson
and James Linn, and the Honorary Secretary, and Treasurer.
ISlutiitors.
Roderick F. Coyne, C.E., and Thomas W. Kilcour.A. A.
Society's Library, Museum, and Rooms, No. 5 St Andrew Square, Edinburgh.
Assistant Libi-arian and Dawso:».Officey—'Mr
All Ci'iiimunicalions and Donations to be addressed to the Honorary Secretary,
.35 Castle Street, Edinburgh.—
TRANSACTIONS
OF THE
EDINBURGH SOCIETY.GEOLOGICAL
SESSIONS 1874-7 r.
Thursday, 5th November 1874.
5thThe Society held its Forty-First Anniversary Meeting on
wasNovember 1874, when the following Inaugural Address
delivered by Professor H. Alleyne Nicholson, one of the Vice-
:Presidents of the Society
INAUGURAL ADDRESS,
Palceontological the Migrations Animals.On the Significance of of
Alleyne Nicholson, M.D., D.Sc, F.Pt.S.E, F.G.S.,By H.
Professor of Natural History in the University of St Andrews.
"The Introductory Address," which is usually delivered at the
commencement of the Annual Session of most learned societies,
is very properly intended to be of interest to all the members of
the body before which it is given. Hence such addresses usually
deal with the internal affairs of the Society itself, or are con-
cerned with the current condition of the special science which
the Society may happen to cultivate. That the custom here
indicated is, in a general way, a good one, I cannot doubt. I
am not, however, without the precedent of high authority in
departing from this custom to-night ; and I intend, therefore,
rather to occupy your attention this evening with a few remarks
upon a subject to which, it is true, I have been led by my own
special studies, but which, nevertheless, has a general interest
for all those who are engaged in the elucidation of geological
phenomena.
The subject upon which I have chosen to address you to-night
concerns the conclusions which may be drawn by the palaeonto-
logist from his study of the migrations of animals. This subject
has been handled more or less fully by Sir Charles Lyell in his
Vol. III.—PART I. A"
F.liINliriMJH GEOLOGICAL SOCIETY.2
" of Geolop;}'," and has also beengreat work on the Principles
;
"iJarwin in the Origin of Speciesincidentally treated of by
De Yerneuil, and other eminentwhilst Barrande, Edward Forbes,
drawn attention to it in various portionspalaeontologists have
such distinguished authorities, I doof their works. In following
your attention to any extent with the fornot propose to occupy
well-known facts relating to the migrations ofthe most part
animals. I may have occasion to summariseexisting species of
facts, but that will be all. On the contrary, I pur-some of these
remarks to the bearing of these admitted factspose to continemy
interesting geological and biological questions.upon various
point out to you the importance of the generalI need hardly
the migrations of animals as regards the science ofsubject of
what we believe upon this subject mustgeology. Upon
"depend what we understand by the term con-ultimately
"
as applied to different groups of strata. Thattemporaneous
stratified rocks of the earth's crust are, wherever we maythe
examine them, divisible into a succession of definite groups or
" formations," is admitted by every geologist. That we cannot
compare the successive formations of two different and remote
except through the organic remains which they may con-areas
tain is also universally conceded. Lastly, it is a matter of
general belief, that when we find two formations in widely
detached portions of the earth's surface containing the same
thenfossils, or an assemblage of similar and representative forms,
" Aswe have to deal with two contemporaneous " formations.
attach theI have just said, however, all geologists would not
" viewssame meaning to the term contemporaneous," and their
what theyupon this fundamental question would depend upon
animalsbelieved about the migrations of animals, and of marine
would attach thein particular. The oldest view is one which
" and wouldnatural signification to the term contemporaneous,"
different regions werehold that contemporaneous deposits in
period. The more modernreally deposited at precisely the same
"hold that the word contem-view, on the other hand, would
by geologists, is to be construed in aporaneous," when employed
not been laid down at the sameloose sense. Such deposits have
though, speaking geologically, the intervalactual point of time,
"
"small one. They are homotaxeouswhich separates them is a
contain similar fossils, because the animalsdeposits and they
area migrated extensively into the other. Hence,inhabiting one
two formations containing similar or identical fossils,on this view,
geographically far apart, would be held in all cases toif placed
in point of age, the dilference between them being thediffer
of time which would be refpiired for the migration of thelength
aniinals of the odh area to the other, it is obvious, therefore,
that the establishment of this exceedingly important viewON THE MIGRATIONS OF ANIMALS. 6
occur-compels us to prove the common, and indeed constant,
periods of therence of migrations of animals and plants at all
earth's history, and to this point we shall first turn our attention.
is one, inWe may first take the case, and it a not uncommon
ofwhich we find the same species of fossil, or the same group
uppermost of three groups ofspecies, recurring in the related
middlebeds, but absent in the series ; supposing, of course, that
area or two areas geographicallythe beds occupy the same close
an example from what we in thetogether. I may take see
Medina sandstone,Hudson Kiver group, the and the Clinton
Here we find the Eiverformation of North America. Hudson
withdeposits, the lowest of the three, to be charged numerous
pctropolitanus, Halysitcsfossils, amongst which Chcetdes catemi-
laria, Leptcena sericea, StrojoTioviena alternata, Orthis Mforata,
bilobattis,Ortliis testudinaria, and Bellcroplw)i may be mentioned
as common forms. All these species reappear in the Clinton
formation, the highest of the three groups ; but they have all
the intermediatehitherto proved to be absent from formation of
the Medina sandstone, though this formation is not absolutely
destitute of fossils, and varies in thickness from 100 to over 1000
feet.
Precisely similar phenomena, as I have elsewhere shown
(" Quart. Journ. Geol. Soc." August, 1872), can be proved to have
occurred, if we examine the Graptolites of the iSkiddaw slates,
and the Coniston mudstones of the Lake District. Thus, to
take two species only, we find Diplograptus pristis and Climaco-
grap)tus teretiusculus occurring in the Skiddaw slates, and in the
Coniston mudstones, but absent in the intermediate series of the
Borrowdale rocks, or Green Slates and Porphyries.
Facts of this kind could be readily multiplied, and they do not
appear to admit of more than one explanation. When we find
the same species present in the same area in two different rock-
groups, but absent from the area in sediments intermediate
between those groups, we are obliged to suppose that we are deal-
ing with a case of migration. At the close of the deposition of
the fi