410 
CARBONIFEROUS WHETSTONE GRITS. 
chapter upon the banks of the 1 chussovaya river. Certain bands of a red colour 
and fissile texture, which are loaded with encrinites, alone diversify the mass of 
grey limestone with which they occasionally alternate. 
The dominant fossils of this upper portion of the limestone are corals of the 
genera Cyathophyllum, Lithostrotion, Syringopora ( Harmodites distans, Fisch.), with 
Productus hemispharicus (minor), P. comoides, var., and Orthis arachnoidea. 
Whetstone strata. — It is probable that the above-mentioned masses represent 
the lower and middle portions only of the Carboniferous system of this Arctic 
country. They are, in fact, overlaid by a thick series of argillaceous sandy beds, 
here and there schistose, which in the vicinity of the limestone nartake of all its 
great and sudden flexures, and are perfectly welded on to it. Further westwards, 
their inclination becomes less and more regular, their direction being north-east. 
The sandy beds are made up of grains of Lydian stone and of grey, green and red 
quartz rock, imbedded in a fine felspathic or argillaceous matrix of greenish-grey 
and whitish colour, the quantity of which is so minute that it cannot be discovered 
by the naked eye. The siliceous grains, more or less rounded, are sometimes very 
small, but occasionally so large as to form a conglomerate grit. The prevailing 
colour of the whole rock is that of pounded black pepper ; and it is divided into 
numerous powerful beds, traversed by joints which are seldom continuous. Where- 
ever these beds alternate with strong courses of greyish and reddish shale (clay), 
they are rounded off into slopes covered by gravel and vegetation ; and they pre- 
sent clear and good sections only, where they are hard and sandy. Near the village 
of Sariu, the conglomerate courses expand into a true “ Nagelfluhe,” not less 
than twenty feet thick, containing grains of carbonate of copper. Plants having 
the “ facies ” of the carboniferous flora occur, and the whole group, being as before 
said, quite conformable to the carboniferous limestone, must be included in the 
same system. 
The section of the very symmetrical hill near the Petchora river (PI. V. fig. 2,), 
from whence the whetstones are extracted which are used over nearly the whole of 
Russia, establishes, beyond contradiction, the correctness of that view. The little 
river Sophiusa washes the base of this hill, and exposes a dome of carboniferous 
limestone, divided into thin flagstones towards the base, and thick beds near the 
summit : on both sides of the dome, these limestones are equably and conformably 
overlaid by shale, and a pepper- coloured whetstone identical with that of the Iletsk. 
The bed extracted for whetstones does not exceed three to four feet in thickness. 
