Sketch of the Geology of Northern Russia. 19 



a surface as distinctly rounded and water worn, as the bowlders or 

 colossal pebbles that lie around their bases." In some places the de- 

 tached masses of rock are so thickly scattered, as to prevent the cul- 

 ture of the earth. Another fact, illustrative of the diluvian action 

 from north to south in this quarter, is, tliat the parent rocks of the 

 bowlders in the vicinity of Petersburg, are recognised in situ in Fin- 

 land, while new varieties of rolled masses are there found, brought 

 from rocks existing still farther north. 



Immense quantities of iron are smelted at Petrozavodsk from bog 

 iron ore, obtained by dragging the lakes. Plumbago is found, but 

 of inferior quality. 



South of this primitive district, follows a distinct secondary forma- 

 tion, the lowest of which is a pale blue clay, probably resting on the 

 older rocks just described. Upon this are found sand, and sandstone, 

 shale, and limestone, containing organic remains. These three stra- 

 ta run in a continuous formation from Sweden through the Baltic Isles, 

 Esthonia, and Ingria, in an east north east direction to the isle of 

 Wolves. 



JVorthern salt district. 



Red marl and sand are the peculiar features of the salt formation 

 in every part of the globe, containing subordinate beds of sulphate of 

 lime. Rock salt, and salt springs are of frequent occurrence in the 

 central and south parts of Russia. The northern salt district extends 

 in a line parallel with the limestone of Petersburg for one thousand 

 versts. Gypsum, resembling oriental alabaster, is quarried in many 

 parts of this district, and is extremly beautiful. 



Valday Hills. 



The elevation of the hills is not more than eight or nine hundred 

 feet, but they are the most considerable chain between the Baltic and 

 Black Sea, and form the ridge from whence the waters descend nortli 

 and south through a vast extent of country. The Duna flows from 

 their western extremity into the Baltic, and the Dneiper into the 

 Black Sea, — east at a small distance, rises the mighty Volga, which, 

 receiving as tributaries the waters of eastern and central Russia, tra- 

 verses in its various windings, a distance of four thousand miles, 

 bearing on its bosom the commerce of Russia, China, Siberia, Persia 

 and central Asia, and finally falls into the Caspian. Many inferior 

 rivers on the northern descent, after passing through a series of lakes, 



