308 Horner's Geological Address. 



lected were carefully examined by skilful conchologists. Dr 

 Beck of Copenhagen considered all he examined to be iden- 

 tical with those now existing in northern seas which range 

 from 42° to 84° south latitude. Mr Smith of Jordan Hill 

 was of opinion, that, though many of these species are recent, 

 some are of peculiar varieties, now found in desiccated and 

 elevated sea-beaches only. Mr Lyell recognised the group 

 as identical with that which he had described from Udde valla 

 in Sweden, a distance of a thousand miles from the Dwina ; 

 and Mr G. Sowerby stated, that the shells, though on the 

 whole an association of existing species, have yet among 

 them forms seldom, if ever, found except in raised sea-bottoms 

 of a subfossil character. The authors estimate the place 

 where these shelly beds occur to be about 150 feet above the 

 sea at Archangel, and consider them to afford undoubted 

 evidence, that the land, from the Vaga to Archangel, was a 

 sea-bottom during the period of existing species. A similar 

 estuary appears to have existed about 300 miles eastward, 

 in the valley of the Petchora ; for Count Keyserling found 

 fragments of sea-shells, apparently of existing arctic forms, at 

 a distance of 180 miles from the present embouchure of that 

 river, strewed upon argillaceous slopes in the depression of 

 the valley. He further observed, that they do not occur in 

 the adjoining plateaux ; and that these higher grounds are 

 occupied by sand, gravel, and clay, containing here and there 

 bones of the mammoth, from which he infers, that the shelly 

 deposites were formed in a bay of the sea that extended far 

 into low lands, which were then inhabited by great extinct 

 mammalia. 



In the sketch given by the same authors of the structure 

 of Siberia, they adduce a body of very satisfactory evidence 

 to justify the inference they draw, that the vast region in 

 which the bones of mammoth, rhinoceros, and bos iiriis, are 

 so abundantly dispersed, and especially the wide and low tract 

 of northern Siberia, and all the low promontories between 

 the Obe, the Yenessei, and the Lena, were elevated at a pe- 

 riod long subsequent to the time when large herds of these 

 animals for many successive generations inhabited that re- 

 gion. Following up the views first propounded by Mr Lyell, 



