114 



POST-PLIOCENE PERIOD. 



[Ch. X. 



age, referable to the recent division of the post-tertiary epoch as 

 determined by the organic remains which accompany the stone imple- 

 ments. But memorials have of late been brought to light of a still older 

 age of stone, when man was contemporary in Europe with the ele- 

 phant and rhinoceros, and various other animals, of which many of 

 the most conspicuous have long since died out. The alluvial and 

 marine deposits of this remoter age, the earliest to which any vestiges 

 of man have yet been traced back, belong to a time when the physi- 

 cal geography of Europe differed in a more marked degree from that 

 now prevailing than during the latter part of the post-tertiary period, 

 when the valleys and rivers coincided almost entirely with those by 

 which the present drainage of the land is carried on, and when the 

 peat-mosses were the same as those now growing. So, also, the situa- 

 tion of the shell-mounds and lake-dwellings above alluded to is such 

 as to imply that the topography of each district where they are 

 observed has not subsequently undergone any material alteration. In 

 some exceptional cases, it is true, a marked change has been brought 

 about by the rising or sinking of the earth's crust in the neighborhood 



Fig. 106. 



v. 



Eecent and Post-pliocene alluvial deposits. 



1. Peat of the recent period. 

 Gravel of modern river. 

 Loam or brick-earth (loess) of same 



age as 2, formed by inundations of 



the river. 

 Lower-level valley-gravel with extinct 



mammalia (post-pliocene). 

 Loam of same age. 



Higher level valley-gravel (post-plio- 

 cene). 



Loam of same age. 



Upland gravel of various kinds and 

 periods, consisting in some places 

 of unstratified boulder clay or gla- 

 cial drift. 



Older rocks. 



of the sea, so that raised beaches occur at moderate heights rarely 

 exceeding twenty-five feet above high-water mark ; or in other places 

 submerged forests are seen at low water, skirting the coasts ; and we 

 may take for granted that similar or even greater movements have been 

 experienced far inland within the same era, although we cannot recog- 

 nize them, or appreciate their magnitude, for want of a standard of 

 measurement such as that which the contiguity of the ocean affords. 

 These movements, whether upward or downward, have affected some- 

 what uniformly very wide areas, so as not greatly to derange the 

 local features of such an extent of country as the eye can embrace at 

 one view. But we no sooner examine the post-pliocene formations in 

 which the remains of so many extinct mammalia are found, than we 

 at once perceive a more decided discrepancy between the former and 



