399 
Petersburgh and of Archangel, which, flowmg from N.N.W. to 
S.S.E., or transverse to the only apparent: lines of elevation, might 
be expected to offer the evidences required. ‘They also ascended the 
great Dwina, from the White Sea to Oustiug Veliki; and afterwards 
extended their researches to the south of Nijnii Novogorod, in order 
to determine the relations of the secondary rocks to those older 
deposits with which they had become familiar. 
In terminating these introductory explanations, the authors dwelt 
with pleasure on the valuable assistance they had received, particu- 
larly m the early part of their tour, from the Baron A. de Meyen- 
dorf*, now executing, by order of his Imperial Majesty, a statistical 
survey of Russia, who endeavoured to combine geology and natural 
history with the chief object of his expedition by attaching to it two 
excellent naturalists, Count Keyserling and Professor Blasius. They 
further testified ‘their warm thanks tu the Russian minister, the 
Count de Cancrine, who specially aided this geological inquiry, and 
they also acknowledged their obligations to Count Nesselrode, Count 
Alexander Strogonoff, Baron Humboldt, Baron Brunnow, and Gene- 
ral Tcheffkine. They further expressed their sense of the value of 
the services of a zealous young geologist, Lieutenant Koksherof, 
without whose aid the authors could not have accomplished their 
task. A geological map and'sections illustrated the description, and 
the characteristic fossils of each group were laid upon the table. 
Crystalline Rocks, Metamorphic Rocks, Trap Rocks, Physical Geo- 
graphy, &c.—Before they proceed to describe the sedimentary de- 
posits in their order from 8. to N., or from the older to the younger 
strata, the authors mention some peculiar varieties of gneiss which 
occupy the little islands of the White Sea near Onega, one of which 
is charged with garnets. They then give a brief sketch of the 
altered condition of the sedimentary strata on the western shore of 
the lake Onega, where they are pierced by masses of greenstone and 
trappean conglomerate. 
A few words explain how the Waldai Hills, the great watershed 
of Central Russia, afford the best means of reading off the succes- 
sion of the older strata. The rivers Msta, Wolkoff, Siass, &c., 
which flow from the south to the north, having short courses, neces- 
sarily occupy deeper rents, and therefore expose on their banks 
better sections than those streams, which, descending on the other 
side of the crest, glide along on a very slightly inclined plane to the 
south. By examining the banks of the north-flowing rivers, the 
older formations were: found to succeed each other in the following 
ascending order :— 
1. Silurian Rocks.—The oldest sedimentary deposits of Russia 
(those on which St. Petersburgh is situated) are clays, sandstone, 
limestone and flagstone, which from their position and organic re- 
mains are considered the equivalents of the Silurian system of the 
British Isles. The detailed order of these beds was long ago given 
by Strangways; but at the early day when he wrote, the study of 
organic remains was not sufficiently advanced to enable him to de- 
* Assisted by M. Zenofief. 
