GLACIAL GEOLOGY. 229 



the ice, therefore, was not a local pheuoiiieuon, but characterized all 

 the glaciated areas. And the evidence shows that the oscillatious 

 referred to were on a gigantic scale. 



The relation borne to the glacial accumulations by the old river 

 alluvia which contain relics of paleolithic man early attracted atten- 

 tion. From the fact that these alluvia in some places overlie glacial 

 deposits the general opinion (still held by some) was that paleolithic 

 man must needs be of postglacial age. But since we have learned 

 that all bowlder clay does not belong to one and the same geological 

 horizon — that, in sliort, there have been at least two, and probably 

 more, epochs of glaciation — it is obvious that the mere occurrence of 

 glacial deposits underneath paleolithic gravel does not prove these 

 latter to be postglacial. All that we are entitled in such a case to say 

 is simply that the im[)lement-bearing beds are younger than the glacial 

 accumulations upon which they rest. Their horizon must be deter- 

 mined by tirst ascertaining the relative position in the glacial series of 

 the underlying deposits. Now, it is a remarkable fact that the bowl- 

 der clays which underlie such old alluvia belong, without exception, to 

 the earlier stages of the glacial period. This has been proved again 

 and again, not only for this country but for Europe generally. 1 am 

 sorry to reflect that some twenty years have now elapsed since 1 was 

 led to suspect that the paleolithic gravels and cave deposits were not 

 of post-glacial but of glacial and inter-glacial age. In 1871-'72 I pub- 

 lished a series of papers in the Geological Magazine^ in which I set 

 forth the views I had come to form upon this interesting question. In 

 these papers it was maintained that the alluvia and cave deposits could 

 not be of post-glacial age, but must be assigned to preglacial and inter- 

 glacial times, and in chief measure to the latter. Evidence was adduced 

 to show that the latest great develoi)ment of glacier ice in Europe 

 took place after the southern pachyderms and paleolithic man had 

 vacated England; that during this last stage of the glacial period, man 

 lived contemporaneously with a northern and alpine fauna in such 

 regions as southern France; and, lastly, that paleolithic man and the 

 southern mammalia never re- visited northwestern Europe after extreme 

 glacial conditions had disappeared. These conclusions were arrived 

 at after a somewhat detailed examination of all the evidence then 

 available, the remarkable distribution of the paleolithic and ossiferous 

 alluvia having, as I have said, particularly impressed me. I colored 

 a map to show at once the areas covered by the glacial and fluvio- 

 glaeial deposits of the last glacial epoch, and the regions in which the 

 implement-bearing and ossiferous alluvia had been met with, when it 

 became apparent that the latter never occurred at the surface within 

 the regions occupied by the former. If ossiferous alluvia did here and 

 there appear within the recently glaciated areas, it was always either 

 in caves or as infra- or inter-glacial deposits. Since the date of these 

 researches our knowledge of the geographical distribution of Pleisto- 



