ON THE GEOLOGY OF RUSSIA IN EUROPE. 
213 
desiccation of brackish seas, which Hke the present Caspian were 
inhabited by Mollusca requiring a warmer cUmate, then is there 
also a total absence of great boulders. On this point I would 
further beg to remind you, that in our examination of the Ural 
Mountains, even up to 60'^ north latitude, my companions and 
myself could not trace any evidence whatever of boulders having 
been transported from these mountains to great distances upon 
their flanks ; although the peaks rise to heights of 5000 and 6000 
feet above the sea, and the chain extends from north to south 
through eighteen degrees of latitude. In every portion of the 
Ural Mountains, and on both their Asiatic and European flanks, 
the detritus is of a purely local character ; and in it are occasion- 
ally entombed the bones of the Mammoth, Rhinoceros tichor- 
rhinuSj and other extinct quadrupeds, mixed up with gold sand 
and gravel. Transporting ourselves to the south of Russia, we 
find the upper portion of the cliffs of the Sea of Azof composed 
of local detritus and clay equally charged with the same remains. 
The general examination of Eussia proves in the most emphatic 
manner, that the central masses of her continent, though exempt 
from all plutonic ageecy, have undergone grand but tranquil 
oscillations which have scarcely at all disturbed the physical out- 
lines of the ancient bottoms of the sea — oscillations which have 
operated in a similar manner over this vast space from the re- 
mote Silurian age, to the close of the period antecedent to tne 
historic sera. This survey has also taught us, that the great 
Russian continent is surrounded by rocks of igneous origin, the 
eruptions of which have corrugated and diversified certain por- 
tions of the surface at different periods. 
On her eastern or Asiatic side it has been the wish of my 
friends and myself to endeavour to read off in the Ural Moun- 
tains the effect of such derangements, and to trace the sedimen- 
tary deposits of Russia through the mazes of that band of great 
disturbance. Having so recently laid before you the outline of 
our views concerning this chain, and being aware that you will 
