114 
POPULAR SCIENCE REVIEW. 
Mr. James Geikie, in his book on “ The Great Ice Age,” 
actually makes two glacial epochs with an interglacial period 
between them, into which period he introduces — 1st, a milder cold 
temperate climate, with the mammoth, the woolly-coated rhi- 
noceros for denizens of our forests, and the great hear dwelling 
in our caves, the winters still severe. 2nd, a warmer subtropical 
climate, with the retreat of the arctic mammalia northwards, 
and the advance from the south of the hippopotamus, the cave- 
lion, the hygena, and palaeolithic man, evidenced by the rude 
flint implements found in valley gravels. 
Then followed another cold period, before which the southern 
mammalia disappeared, and were again succeeded by arctic 
animals. Even these, however, migrated southward, leaving the 
land to be again overspread with ice and snow. 
Mr. Geikie admits that there were not unfrequent shiftings 
in the distribution of land and sea, but these do not seem to 
him to have been the chief causes of these climatal changes. 
After this second cold period, Mr. Geikie next introduces the 
submergence of the British Islands to 2,000 feet ; gives it a 
final refrigeration, in which period the drifts and angular erratic 
blocks were scattered over the South of England, and over North 
Germany and Russia, and the Swiss glaciers were augmented. 
Then Britain for the last time — 
Arose from out tlie azure main, 
to he again re-forested and re-peopled, this time by the moose- 
deer and the cariboo or reindeer, the arctic fox, the lemming, 
and the marmot ; and Neolithic man became the denizen of 
our caves and woods, and made pictures of the animals he there 
saw and hunted. 
The only considerable change which Mr. Geikie proposes to 
introduce at this period is the severance of our island from the 
continent, and the complete insulation of Britain. 
I hope it may he possible to simplify this chapter of our 
Glacial epoch, and here I am glad to say I have the high 
authority of Professor Nordenskiold, who has visited both Spitz- 
hergen and Greenland more than once, that from the evidence 
of fossils obtained in a succession of beds in arctic latitudes, he 
is led to the conclusion that there has not been in past geo- 
logical times a periodical alternation of warm and cold climates 
on the surface of the earth. 
In Eocene Tertiary times suh-tropical conditions prevailed in 
the latitudes of London and Paris, and both plants and animals 
betokened a temperature at least as high as that of North 
Africa. 
Since that period, through Miocene and Pliocene formations, 
we are able to trace a gradual lowering of the temperature of 
