106 REPORT—1840. 
immense distances, with few or no alterations in its mineral characters, 
or organic remains. 
Two great difficulties, however, are opposed to the examination of 
this region,—the slight altitude of the masses above the sea, and the 
vast quantity of drift or superficial detritus, which obscures the funda- 
mental rocks. ‘To conquer these difficulties, the authors examined, in 
succession, all the principal banks of the rivers between the longitude 
of St. Petersburgh and that of Archangel, which, flowing from N.N.E. 
to S.S.W., might be expected to offer the evidences they required ; 
and having ascended the great Dwina, from the White Sea to Ous- 
tiug Veliki, they afterwards extended their researches to the south 
of Nijnii Novogorod, and the edges of the province of Tambof, in order 
to determine the relations of the secondary rocks to those older deposits 
with which they had become familiar. 
The formations were found to succeed each other in the following 
ascending order :— 
1. Silurian Rocks.—The oldest stratified deposits of Russia (those on 
which St. Petersburgh is situated) are clays, sandstone, limestone, &c., 
which, from the organic remains they contain, must be considered the 
equivalents of the Silurian system of the British Isles. The detailed 
order of these beds “per se,” was long ago accurately given by Strang- 
ways; but at the early day when he wrote, the study of organic remains 
was not sufficiently advanced to enable him to determine their place in 
the geological series, nor to point out their true relations to the adja- 
cent masses. Many of the organic remains have been described by the 
native authors, Eichwald and Pander, and some very characteristic 
forms very recently by M. de Buch, from specimens sent to him by Col. 
Helmersen. These Silurian deposits occupy the islands of Oland, Goth- 
land, &e. in the Baltic, and trend along the shores of Courland in a broad 
band from W.N.W. to E.N.E., till they are lost under vast heaps of gra- 
nitic detritus between the lakes Ladoga and Onega. Near the latter lake 
these deposits are deflected to the north, and there meet with great ridges 
of trappean rocks, which run from N.N.W. to 8.S.E. In that region all 
the deposits are in a metamorphic condition ; the limestones present few 
distinct traces of fossils ; and the authors having satisfied themselves that 
there was no chance of observing any further evidence of a descending 
order between such rocks and the great primary granitic chain of 
Scandinavia and Russian Lapland, the boundary of which they coasted, 
confined their attention to the ascending order of the strata. 
2. Old Red, or Devonian System.—That the inferior strata were the 
true equivalents of the Silurian system, was determined not only by 
their aspect and fossil contents, but by their passing into other over- 
lying rocks which are completely identical with the “‘ Old Red System” 
of the British Isles, as defined by Mr. Murchison*. This system is of 
enormous extent in Russia; ranging from the borders of Poland 
Lithuania is chiefly composed of it, and Do6rpat is in its centre. It 
thence passes by the lakes of Ilmen and the Waldai Hills, and is ex- 
tended over a vast region to the E.N.E., where it constitutes a large 
* See Silurian Researches, p. 165, and Table with the Map. 
