AGE OF MAN. 577 



It follows, therefore, not only that some of the large Mammals 

 continued on beyond the time of their meridian nearly or quite 

 through the Terrace epoch, but also that the modern tribes came 

 into existence before their extinction. The progressing Terrace 

 epoch was bringing about the cooler climate required for the mo- 

 dern species ; and this change of climate was also causing the dis- 

 appearance of the tribes of the older era. 



The time of greatest expansion of the Post-tertiary races was probably in the 

 Champ] ain epoch, when they would have found the warm climate over the conti- 

 nents, which they required (p. 567). Now, the modern species correspond to a 

 climate like the present, which is a colder one. The Glutton, of Lapland, the 

 Reindeer, and the Polar Bear were among the earliest of these modern species, 

 showing that when they began this cooler climate existed. Since the faunas 

 of the Post-tertiary and age of Man are thus distinct in the climate which they 

 required, they must have belonged essentially to different epochs, — the modern, 

 of course, to the later. The Terrace epoch was the one in which the change to 

 the colder modern climate was in progress, and therefore that which would have 

 favored the appearance of the modern types and brought about the disappear- 

 ance of the more ancient. 



The cooler climate might have been begun over Europe and Asia in the early 

 part of the Terrace epoch, by an increase of Arctic lands, before the terrace 

 elevations of central Europe had made much progress. 



The succession of recent formations in Europe and Switzerland, from the 

 early Post-tertiary onward, is thus given by Professor Guyot from his own 

 and other observations : — 



1. The northern European and American Glacial drift, the Glacial epoch. 



2. The epoch of subsidence, or Champlain epoch, when the large Post-tertiary 

 fauna was fully developed. 



3. The " ancient diluvium" of Switzerland. In some places it is hundreds of 

 feet thick, and generally stratified; part of it is pebbly, with the rounded stones 

 sometimes from the size of an egg to that of a man's head, but none of them 

 are scratched or polished. It covers the plains about Lake Geneva and the low- 

 lands of Switzerland, and underlies the moraines of the great Swiss Glacier 

 (p. 545), and contains, though rarely, bones of the Ursus spelseus, Felis sj^elsea, 

 Elephas primiyenius, Rhinoceros tichorinus, Hippopotamus^ etc., without any re- 

 mains of modern species. 



4. The Drift of the great Glacier of Switzerland, together with the Terraces 

 and Loess or silt of the river-borders. It may belong to the American Terrace 

 epoch. The true Drift is unstratified, and spreads upward over the hills; the 

 stones are scratched and polished, and in part lie in distinct moraines, or are mixed 

 with glacial mud. The alluvium or loess covers this Drift. It is well seen in 

 the valley of the Rhine north of Basle, where it overlies the continuation of the 

 old diluvium of Switzerland. It is sometimes one hundred feet thick, and ex- 

 tends up several hundred feet above the bottom of the valley. It contains a 

 rast amount of land-shells, of existing species ; but they have the small size and 

 aspect that belong to those now found in the Alps 6000 feet above the sea. 



Near Geneva, at Matteguin, there is a bone-bed ten to fifteen feet below the 



38 



