Changes in the Relative Level of Sea and Land. 309 



to whom they do full justice, they infer that the change of 

 climate, the diminished temperature, occasioned by the in- 

 crease of land when the sea-bottoms of these estuaries and 

 shores were upraised, caused the extinction of these great 

 quadrupeds. 



Although the great tract of country from the Baltic to the 

 elevated region westward of the Ural Mountains has not 

 been locally broken up by eruptive rocks, there is ample evi- 

 dence to prove that it has been subjected to the action of 

 subterranean forces, which elevated the whole region, after 

 the deposition of Miocene tertiary beds, and after the land, 

 while submarine, had assumed its present form. " From 

 the German Ocean and Hamburgh on the west to the White 

 Sea on the east, a vast zone of country, having a length of 

 near 2000 miles, and a width varying from 400 to 800 miles, 

 is more or less covered with loose detritus, including erratic 

 crystalline blocks of colossal size, the whole of which blocks 

 have been derived from the Scandinavian chain." The 

 eastern and south-eastern boundary of these erratic blocks 

 mark the line of coast westward of which all the land as 

 far the shores of the Baltic was then submerged. Betw^een 

 that line of coast and the Urals is the region that constitutes 

 the Government of Perm, Viatka, and Orenburg ; and for a 

 considerable space to the west of the Ural, there is not a 

 vestige of any superficial deposite which can be referred to 

 the influence of the sea. " We believe, therefore," says the 

 authors, " that the region so characterised was really above 

 the waters, and inhabited by mammoths, when the erratic 

 blocks were transported over the adjacent north-western sea." 

 The amount of this elevation, subsequent to the covering of 

 the sea-bottom by the northern drift, must have been at least 

 from 800 to 1000 feet ; for the tops of the Valdai Hills, a 

 range on the eastern borders of Lithuania, and to the south 

 of the Government of St Petersburg, which rise in some 

 places to that height, are covered with these blocks on their 

 southern slopes. 



Mr Lyell, speaking of the country near Savannah in North 

 America, says, '* It is evident that at a comparatively recent 

 period, since the Atlantic was inhabited by the existing 



VOL. XLI. NO. LXXXII. — OCTOBER 1846. X 



