TRANSACTIONS OF SECTION C. 563 



Stages of Mortillet (Chellkkxnb) culminated according' to Boule during^ the last 

 interglacial epoch, while the more recent pnlroolithic stages (Mousti^ikienne, 

 SoLUTR^ENNE, and Magdalexienne) coincided with the last great development 

 of glacier-ice. The palaeolithic age, so far as I'Airope is concerned, came to a close 

 during this last cold phase of the Glacial period. 



There are many other points relating to glacial geology which have of late 

 years been canvassed by continental workers, but these I cannot discuss here. 1 

 have purposely, indeed, restricted ray remarks to such parts of a wide subject as I 

 thought might have interest for glacialists in this country, some of whom may not 

 have had their attention directed to the result.s which have recently been attained 

 by their fellow-labourers in other lands. Had time permitted I should gladly have 

 dwelt upon the noteworthy advances made by our American brethren iu the same 

 department of inquiry. Especially should I have wished to direct attention to the 

 remarkable evidence adduced in favour of the periodicity of glacial action. Thus 

 Messrs, Ciiamberlin and Salisbury, after a general review of that evidence, main- 

 tain that the Ice Age was interrupted by one chief interglacial epoch, and by three 

 interglacial sub-epochs or episodes of deglaciation. The same authors discuss at 

 some length the origin of the loss, and come to the general conclusion that while 

 deposits of this character may have been formed at diHerent stages of the Glacial 

 period, and under different conditions, yet that upon the whole they are best 

 explained by aqueous action. Indeed a perusal of the recent geological literature 

 of America shows a close accord between the theoretical opinions of many trans- 

 atlantic and European geologists. 



Thus as years advance the picture of Pleistocene times becomes more and more 

 clearly developed. The conditions under which our old palaeolithic predecessors 

 lived — the climatic and geographical changes of which they were the witnesses — are 

 gradually being revealed with a precision that only a few years ago might well have 

 seemed impossible. This of itself is extremely interesting, but t feel sure that I 

 speak the conviction of many workers in this field of labour when I say that the 

 clearing up of the history of Pleistocene times is not the only end which they have 

 in view. One can hardly doubt that when the conditions of that period and the 

 causes which gave rise to these have been more fully and de6nitely ascertained we 

 shall have advanced some way towards the better understanding of the climatic 

 conditions of still earlier periods. For it cannot be denied that our Imowledge of 

 Palaeozoic, Mesozoic, and even early Cainozoic climates is unsatisfactory. But we 

 may look forward to the time when much of this uncertainty will disappear. 

 Meteorologists are every day acquiring a clearer conception of the distribution of 

 atmospheric pressure and temperature, and the causes by which that distribution is 

 determined, and the day is coming when we shall be better able than we are now 

 to apply this extended meteorological knowledge to the explanation of the climates 

 of former periods in the world's history. One of the chief factors in the present 

 distribution of atmospheric temperature and pressure is doubtless the relative posi- 

 tion of the great land and water areas; and if this be true of the present, it must 

 be true also of the past. It would almost seem then as if all one had to do to ascer- 

 tain the climatic condition of any particular period was to prepare a map, depicting 

 with some approach to accuracy the former relative position of land and sea. With 

 such a map, could our meteorologists infer what the climatic conditions must have 

 been? Yes, provided we could assure them that in other respects the physical 

 conditions did not differ from the present. Now there is no period in the past 

 history of our globe the geographical conditions of which are better known than 

 the Pleistocene. And yet when we have indicated these upon a map we find 

 that they do not give the results which we might have expected. The climatic 

 conditions which they seem to imply are not such as we know did actually obtain. 

 It is obvious, therefore, that some additional and perhaps exceptional factor was at 

 work to produce the riKJOgnised results. What was this disturbing element, and 

 have we any evidence of its interference with the operation of the normal agents of 

 climatic change in earlier periods of the world's history ? We all know that vari- 

 ous answers have been piven to such questions. Whether amongst these the cor- 

 rect solution of the enigma is to be found time will show. Meanwhile, as the 



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