TRANSACTIONS OF SECTION C. 771 
‘information which has already been furnished concerning former climatic condi- 
tions, as the result of careful study of the strata, is probably only an earnest of 
what is to follow when the specialist in climatology pays attention to the records 
of the rocks, and avoids the theories elaborated in the student’s sanctum. The 
recognition of an Ice Age in Pleistocene times at once proved the fallacy of the 
supposition that there has been a gradual fall in temperature throughout geological 
ages without any subsequent rise, and accordingly most theories which have been 
put forward to account for former climatic change have been advanced with special 
reference to the Glacial period or periods, although there are many other interest- 
ing matters connected with climate with which the geologist has to deal. Never- 
theless, the occurrence of glacial periods is a matter of very great interest, and 
one which has deservedly received much attention, though the extremely plausible 
hypothesis of Croll, and the clear manner in which it has been presented to general 
readers, tended to throw other views into the shade, until quite recently, when 
this hypothesis has been controverted from the point of view of the physicist. In 
the meantime considerable advance has been made in our actual knowledge, and 
this year, probably for the first time, and as the result of the masterly réswmé of 
Professor Edgworth David,! the bulk of British geologists are prepared to admit 
that there has been more than one glacial period, and that the evidence of glacial 
conditions in the southern hemisphere in Permo-Carboniferous times is esta- 
blished. Croll’s hypothesis of course requires the recurrence of glacial periods, but 
leaving out of account arguments not of a geological character, which have been 
advanced against this hypothesis, the objection raised by Messrs. Gray and 
Kendall,” that in the case of the Pleistocene Ice Age ‘the cold conditions 
came on with extreme slowness, the refrigerations being progressive from the 
Eocene period to the climax,’ seems to me to be a fatal one. At the same time, 
rather than asking with the above writers ‘the aid of astronomers and physicists 
in the solution of’ this problem, I would direct the attention of stratigraphical 
geologists to it, believing that, by steady accumulation of facts, they are more 
likely than any one else to furnishjthe true clue to the solution of the glacial 
problem. 
I have elsewhere called attention to marked changes in the faunas of the 
sedimentary rocks when passing from lower to higher levels, without the evidence 
of any apparent physical break, or any apparent change in the physical conditions, 
-so far as can be judged from the lithological characters of the strata, and have 
suggested that such sudden faunistic variations may be due to climate. I refer to 
the matter as one which may well occupy the attention of local observers. 
One of the most interesting points connected with climatic conditions is 
that of the former general lateral distribution of organisms, and its dependence 
upon the distribution of climatic zones. The well-known work of the late 
Dr. Neumayr® has, in the opinion of many geologists, established the existence of 
climatic zones whose boundaries ran practically parallel with the equator in 
Jurassic and Cretaceous times, and the possible existence of similar climatic zones 
in Palxozoic times has been elsewhere suggested; but it is very desirable that 
much more work should be done upon this subject, and it can only be carried out 
_by paying close attention to the vertical and lateral distribution of organisms in 
the stratified rocks. 
So far we have chiefly considered the importance of stratigraphical geology 
in connection with the inorganic side of nature. We now come to the bearing of 
detailed stratigraphical work upon questions concerning the life of the globe, and 
here the evidence furnished by the geologist particularly appeals to the general 
educated public as well as to students of other sciences, 
1T. W. E. David, ‘Evidences of Glacial Action in Australia in Permo- 
Carboniferous Time,’ Quart. Journ. Geol. Soc., vol. lii. p. 289. 
* J. W. Gray and P. F, Kendall, ‘The Cause of an Ice Age, Brit. Assoc. Rep. 
(1892), p. 708. 
* M. Neumayr, ‘ Ueber klimatische Zonen wihrend der Jura- und Kreidezeit,’ 
Denkschr. der math.-naturwissen. Classe der h. hk. Ahad. der Wissenschaften, vol. xlvii. 
‘Vienna, 1883. 
