74 
SECTIONS OF THE ANDOMA, ETC. 
intervals beneath the drift to mark its general direction, in a line passing between 
the lake Bielo-Ozero and the town of Kirilof, a few miles only to the north of the 
latter, and thence to the banks of the Dwina near Suskaya. 
On the Andoma near Vitegra the lower or hard grey beds cover the same 
yellow sandstone and carbonaceous shale, and contain the same fossils as in the 
Valdai Hills, viz. the Productus striatus and the Clue teles radians (Fischer). In 
the calcareous woodland plateau of that district, the white limestone of the forma- 
tion assumes, indeed, a character which we have not seen elsewhere. It may be 
called a coral reef, to the formation of which the Cluetetes radians has profusely 
contributed, and the limestone, in some places as white as chalk, has been aggre- 
gated in large concretionary masses, with cavities occasionally containing caverns 
of some extent l 2 . 
Other beds of the limestone in the same district are of dingy yellowish colour. 
On the whole, the strata represented in this woodcut, though clearly forming the 
bottom of the limestone, are not so dark-coloured as in many other places. 
8 bis. 
The lowest carboniferous beds in this section are the sands and bituminous shale (c), which here become very inconsiderable and repose on the 
Devonian rocks (« and i). Then follows the peculiar coralline form of the limestone (d), irregular in its deposit and thinning out on the rise, to give 
place to a great mass of grey limestone (e). 
From all that we could see of the limestone in its course to the north-east, we 
believe, indeed, that its bituminous and dark-coloured beds gradually thin out and 
disappear ; and the coral reefs with Chsetetes were never observed by us to the 
north-east of the canal Maria. 
On the banks of the rivulet Vitegraski, seven versts south of Vitegra, the lower 
limestones, with Chcetetes radians, Harmodites parallelus (Fisch.), and other fossils, 
are, however, much expanded, and form strong cliffs, in which purplish and greyish 
hard bands are associated with a dolomitic variety. Here the limestone overlies 
the usual inferior beds of black, bituminous* shale and incoherent yellow sand- 
1 The pure white colour of this limestone has induced some individuals to reduce great quantities of it 
to powder, and when kneaded into a paste, it is sold chiefly for the purpose of whitening the churches 
and other buildings, according to a custom very prevalent in Russia. 
2 The bituminous schist in parts of this tract might almost be used as a black pigment. 
