IXXX PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



rhinoceros, mastodon and auroclis. The country was then also co- 

 vered to a considerable extent with freshwater lakes, the sites of 

 which are nov/ shown by depressions filled with the detritus in which 

 the bones of these animals were entombed. *' Whether discovered in 

 the gravelly detritus or clay on either flank of the Urals, in the high 

 banks of the great streams which respectively flow into Asia and 

 Europe, or in still greater quantities on the sides of the estuaries of 

 the great Siberian rivers upon the glacial ocean, in all cases the 

 mammoths are found entombed in materials which, whether coarse 

 lacustrine shingle near the mountains, or mud and sand at a distance 

 from them, all announce in the most emphatic manner, that these 

 great creatures lived in lands adjacent to lakes and estuaries, in which, 

 during long ages, their bones were interred, and were sometimes 

 carried out to sea and mingled with oceanic remains*." 



The present watersheds between Europe and iVsia were formed by 

 an increased elevation of the Ural chain, at the time when these 

 animals occupied this eastern land ; and their destruction and ex- 

 tinction is ascribed by the author partly to the disturbance of the 

 land by the upheaving forces, but mainly to the change of climate 

 produced by its increased elevation, audits extension towards the north, 

 the low lands of Northern Siberia having been raised above the 

 water, and the shore of the sea consequently thrown much farther 

 back within the arctic region. '* In the depressions at the very foot 

 of the chain, the mammoth skeletons are broken up, and their bones, 

 together with those of Rhinoceros tichorinus and Bos Urus, are 

 rudely commingled in the coarse shingle, derived from the moun- 

 tains or in the clay above it. In proportion however as we advance 

 into the plains of Siberia, or descend into the valley of the Tobol 

 and the Obe or their affluents, these bones increase in quantity, and 

 are at the same time in much better preservation.' — The wide and 

 low tracts of Northern Siberia, in which these remains are most 

 abundant, were then beneath the sea, and the bones must have been 

 drifted thither, and possibly for some distance. — All the low pro- 

 montories between the Obe, the Yenesei and the Lena, which lie 

 northwards of the ancient ridges and plateaux, were under the 

 waters and estuaries at the periods when the mammoths ranged over 

 the Ural, the Altai, and the adjacent region of Siberia then above 

 the seaf ." 



The form of the ground where the detritus is accumulated, shows 

 that it was deposited after the present configuration of the land had 

 been to a great extent established, when the present valleys existed ; 

 for it fills up all the original inequalities of the inferior rocks, which 

 in many places exhibit appearances of having been worn into holes 

 and cavities, as if by the powerful action of water. The ground is 

 composed entirely of the stony materials of the adjoining hills ; there 

 are no boulders of far-travelled rocks. It is usually from two to 

 twelve feet thick, but there are accumulations of this detritus of 

 more than fifty feet thickness. It is often covered by a thick 

 mass of clay, and this last by peat and bog earth ; so that as the 

 * Page 500. t Page 494-499. 



