130 Murchison jftid Verneull on the Geological Structure 



elevation, might be expected to offer tlic evidences required. They also 

 ascended the great Dwina, from the White Sea to Oustiug Yeliki ; 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, theauthors dwelt with 

 pleasure on the valuable assistance they had received, particularly in the 

 early part of their tour, from the Baron A. de Meyendorf,^ now execut- 

 ing, by order of his Imperial Majesty, a statistical survey of Russia, who 

 endeavoured to combine geology and natural history with the chief ob- 

 ject of his expedition by attaching to it two excellent naturalists. Count 

 Keyserling and Professor Blasius. They further testified their warm 

 thanks to the Russian minister the Count de Cancrine, who specially 

 aided this geological inquiry ; and they also acknowledged their obliga- 

 tions to Count Nesselrcde, Count Alexander Strogonoff, Baron Hum- 

 boldt, Baron Brunnow, and General TchefFkine.t 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 ac- 

 complished their task. A geotegical map and sections illustrated the de- 

 scription, and the characteristic fossils of each group were laid u]3on the 

 table. 



Crystalline Rocks, Metamorphic Hocks, Trap Rocks, Physical Geogra- 

 phy, <Sfc. — Before they proceed to describe the sedimentary deposits in 

 their order from S. 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 gar- 

 nets. They then give a brief sketch of the altered condition of the sedi- 

 mentary 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 succession of the 

 older strata. The rivers Msta, Wolkoff, Siass, &c., which flow from the 

 south to the north, having short courses, necessarily 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 situate) are clays, sandstone, limestone, and 

 flagstone, which from their position and organic remains are considered 



* Assisted by M, Zenofief. 



t General Tcheffkine, Major-General of the School of Mines at St Peters- 

 burgh, and Professor Jacob!, of the Imperial Academy of Sciences, were 

 present at the Glasgow Meeting when the first explanation was offered. 



