158 A general Review of the Geology of Russia. 
After the drainage of the waters from the great Aralo-Caspian 
basin, the depression which forms the Caspian sea of our day did 
not immediately take the configuration which we now behold. 
The water still covered for a long time the Kalmouck steppes to 
the north, extending even to beyond Simbirsk. These low 
plains where are found here and there shells which still live in 
the Caspian sea, resemble completely the hottom of an ocean re- 
cently dried up. Pallas knew well the characters of this de- 
pression and determined with considerable accuracy its ancient 
shores, defined on the northwest by the steep elevation of the 
right branch of the river Volga from Spash to Tzaritzin. 
_ M. de Verneuil now took a rapid survey of the drift formation 
of Russia, and pointed out the limits of this formation as indi- 
cated on the chart. He showed that the extreme points to which 
the Scandinavian blocks have been transported is about six hun- 
dred miles distant from the place where they originated; that 
their course has been tortuous, conforming to the physical geog- 
raphy of the country and passing principally by the vallies of the 
Don and Desna, where the detritus extends farthest to the south. 
He mentioned particularly the fact, that all the erratic blocks of 
ussia have come from Scandinavia and. Finland, diverging as 
they became scattered over Russia. The Ural, like other moun- 
tainous regions of great elevation, has only a local diluvium. 
The authors have arrived at the conclusion, that, after the Ural 
considerable part of Scandinavia and Russia in Europe, as well 
as the north of Germany, was still beneath its waters. . de 
Verneuil considers these facts as proof that the glacial theory is 
not sufficient to account for the principal phenomena of the drift 
formati ussia in - pe, inasmuch as the Ural chain, 
according to that theory, ought to have produced much more 
considerable glaciers than Finland, and also to have contributed 
more to the diluvial formation than that region. Moreover, the 
distance to which these deposits have extended across the coun- 
try, but little disturbed, and far distant from the high mountains, 
requires movements of a different nature from that of terrestrial 
glaciers. 
The second part of the work is devoted to the Ural Mountain 
district, which the authors traversed at eight different points, and 
of which they have given a special geological chart. 'This-chain, 
though it attams but 5000 to 6000 feet, forms one of the prin- 
cipal elevated features of the globe, by reason of its continuity 
and its almost rectilinear direction. Fyom the Straits of Vaigatz 
to the Orsk it comprehends nearly 18° of latitude, deviating but 
little from the meridian. ole 
~The axis of the chain is ordinarily composed of talcose schist 
or chlorite and quartzite, which the authors refer to the Silurian 
