520 FAR-TRANSPORTED SCANDINAVIAN BLOCKS HOW REMOVED. 
in this region is made up of the ruins of the Devonian and Carboniferous rocks, 
over which the current has swept. The former being, for the most part, a slightly 
coherent red sandstone with marls, has contributed to give the dominant colour to 
the mass, whilst fragments of the chert and flint which abound in the latter are so 
profusely distributed, that a geologist unacquainted with the structure of the car- 
boniferous limestone of Russia, might at first si ght really take them to he the relics 
of a chalk formation. In these respects, indeed, the detritus resembles that of 
Moscow and many other tracts. 
Near Jurievetz upon the Volga, we found erratic blocks of quartz rock asso- 
ciated with others of that trap breccia, which we have remarked as peculiar to the 
north-western side of the lake of Onega near Petrozavodsk. Plaving become well- 
acquainted with that rock in situ, and having assured ourselves that it does not 
exist, either to the west or east of the particular zone in question, we had in this 
instance just as clear evidence of the direction in which these fragments had been 
transported for 500 miles from north-west to south-east, as the mineralogists of 
St. Petersburg possess of a shorter southern transport, in the Finnish rocks to the 
south of that city. The blocks of quartz rock and Solamenski-kamen, as seen for 
a stage or tw r o to the south of Jurievetz, Mednikovo, &c., lie upon the higher 
undulating grounds which form the right bank of the Volga, and the general mass 
of the superficial materials on which the blocks repose, are finely laminated yel- 
lowish sands and loams which for the most part obscure the red marls, forming 
the subsoil of the country (see p. 179 et seq.). At Garbatof on the Oka, which 
lies to the west of the tract in question, and at several localities along the banks 
of that stream, we found materials of northern drift in the overlying detritus, often 
of considerable thickness, but in none ot these instances could we discover a trace 
of the peculiar rocks which constitute the promontories of Petrozavodsk on the 
right bank of the Lake Onega, the northern erratics being chiefly granites or gneiss, 
such as occur in situ to the north of the Lake Ladoga (see Map, PI. VI.). 
We have said that the blocks to the south-east of Jurievetz occupy undulating- 
grounds rather higher than the adjacent depressions, and in such positions w T e also 
observed them towards Nikolsk, and also on high cliffs overhanging the Suchona 
river, between Totma and Ustiug. To the south and to the north of the last-men- 
tioned town, northern granitic blocks are also seen 1 ; and we were struck with 
1 The shrine of St. Procopius in the cathedral church of Ustiug is in high reputation with the natives, 
because about 300 ) ears ago that holy man is said to have saved Ustiug from being destroyed by a shower 
