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, that the parent rocks of the 
bowlders in the vicinity of Pertersburg, are recognised in situ in Fin- 
land, while new varieties of rolled masses are there found, brought 
from rock existing still farther north. 
Immense quantittes 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- 
tarun ina continuous formation from Sweden through the Baltic 
Isles, Esthonia, and Ingria, in an east north east direction to the isle 
of Wolves, 
Northern 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 extremely beautiful. 
Valday Hills. 
‘The elevation of the hills is not more than eight or nine hundred 
féet, but they are the most considerable chain between the Baltic and 
Black Sea, and form the ridge from whence the waters descend north 
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 2 series of lakes, 
