Page:Quarterly Journal of the Geological Society of London, vol. 28.djvu/525

1872.] 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 Mammoth. 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-deposits, corresponding to these climatal changes of long duration. We should find the Hippopotamus and Spotted Hyæna in those which were accumulated during the warm, the Reindeer, Glutton, and Marmot in those which were deposited in the cold period. 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 Forest-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 Magazine,' 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:—