1872.] DAWKINS — CLASSIFICATION OP TLEISTOCENE STRATA, 431 



snow, similar to those which Admiral von "Wrangel describes in 

 Northern Siberia, and Sir John Franklin in the area north of the 

 Canadian lakes. 



The two other views which have been held as to the climate of 

 the Pleistocene age must now be very briefly examined : — • 



1. Mr. Prestwich, fixing his attention more particularly on the 

 evidence afforded by the contorted gravels and ice-borne pebbles in 

 the river-deposits, has inferred that the climate was severe, and that 

 the presence of the Hippopotamus in Britain may be accounted for 

 on the hypothesis that it was clad in wool and hair, like the Mam- 

 moth. To this Sir John Lubbock objects that so aquatic an animal 

 could not have lived here at the time that the rivers were frozen 

 over. It seems to me also that such a change in the physique of 

 the animal as Mr. Prestwich supposes could not have existed 

 without leaving behind greater differences than we find between 

 it and its living African representative. There were also other 

 African animals in Britain, as well as the Hippopotamus. 



2. The second view, or that of Sir John Lubbock and Mr. J. 

 Geikie, accounts for the presence of arctic and African animals in 

 Britain by the hypothesis that the one group occupied the country 

 during a cold and the other during a hot period — in other words, 

 that the swinging to and fro of the animal life depended upon secular, 

 and not seasonal changes. Now, if this be true, we ought to find 

 the remains of the animals in two distinct suites, in the river-de- 

 posits, corresponding to these climatal changes of long duration. 

 AVe should find the Hippopotamus and Sj)otted Hysena in those which 

 were accumulated during the warm, the Reindeer, Glutton, and 

 Marmot in those which were deposited in the cold i^eriod. After 

 seeking for evidence of this for the last ten years, I cannot find the 

 slightest trace of any such sequence in Britain or on the Continent. 

 After the Pleistocene had fairly set in, as marked by the Porest-bed, 

 and after the arctic mammalia had arrived, their remains are found 

 lying side by side with those of the African species, in the same 

 river-strata, and under the same physical conditions. Nor can this 

 be accounted for by the supposition that the two series of remains 

 have been accumulated at two different times, separated from one 

 another by a wide interval — because in that case the one would be 

 more decomposed than the other, or more rolled by water than the 

 other. It is also a great demand on scientific faith to hold that in 

 so many old river-deposits, as, for example, at Bedford, Acton Green, 

 and Salisbury, the two series could by any possibility have been so 

 intermingled as they actually are found to be, unless the animals to 

 which they belong had been living at the same approximate time 

 in the same region. This view is therefore untenable, so far as it 

 is based on the false assumption that the remains occur in the river- 

 strata in two distinct suites. 



Mr. James Geikie, in a very able article in the ' Geological Maga- 

 zine,' vol. ix. no. 4, brings forward the following objections to the 

 view that the intermingling of the African with the Arctic species 

 is due to climatal extremes : — 



