DETACHED COAL STRATA OF PETROFSKAYA. 
115 
This thin-bedded rock, though absolutely subordinate to white and other marls 
with gypsum, contains small Producti very analogous to fossils of the Zechstein ; 
one, indeed, having since been identified by Mr. J. Sowerby with the P. horridus 
of the English magnesian limestone, whilst another shell is undistinguishable from 
the Leptcena sarcinulata of the Carboniferous rocks. 5. White and grey marl- 
stone in layers with gypsum. 6. Red and brown marl and gritty sandstone, inter- 
laced with gypseous flags and pure white gypsum. 7. Coarse pebbly calcareous 
deposit (see PL I. fig. 3.) : these beds are exposed in a succession of low hills 
within the distance of three versts, and they all plunge westwards and form the 
eastern side of the vale of Bachmuth. 
We have no doubt that this red and yellow group represents as a whole the 
Permian system hereafter to be described, and we trust that future geologists will 
be enabled to give other and more detailed sections, showing the exact manner in 
which the carboniferous strata pass upwards into that deposit, which occupies the 
valley of Bachmuth and its slopes '. 
Outliers of the Carboniferous Rocks at and around Petrofskaya, 8fe. fyc. — Besides 
the great southern coal tract, carboniferous strata associated with limestones similar 
to those we have described, are visible about two versts to the west of the military 
colony of Petrofskaya on the right bank of the Upper Donetz. 
The intervening country between Bachmuth and this spot is occupied by over- 
lying red sandstone (Permian?), Jurassic rocks, chalk, &c. The coal strata which 
we examined at this spot are exposed in a ravine at a slight elevation above the 
Donetz and its tributaries, and are overlaid by incoherent materials of reddish sand 
1 In reference to this section, we must state that we urged our friend Major Teploff, who accompanied 
us, to endeavour to work out this point upon returning to his station. In the mean time it may be ob- 
served, that in a memoir illustrated by a small map and several sections, published in the Russian edition 
of the ‘ Journal des Mines,’ 1838, Capt. Ivanitzki has described the environs of Bachmuth. We feel con- 
fident that many of the red rocks near Bachmuth, with gypsum, conglomerate, &c., which he referred to 
the Keuper and Red Sandstone, constitute an integral part of the Permian system. Indeed our section 
above proves that they are intimately connected with the limestones with Producti we have just de- 
scribed. The sections of Capt. Ivanitzki exhibit alternations of limestone with green and red clays, 
gypsum, &c„ on the banks of the Kolima, a tributary of the Bachmutka. Other beds of his “ marnes 
irisees” consist of large concretions of gypsum, subordinate to red and green argillaceous marl ; and again, 
other strata, which are horizontal as well as curved and highly inclined, and which occur on the Donetz, 
Soukaia-plotiva and Bachmutka rivers, are red, greyish, and ferruginous grits and conglomerates, sands, 
argillaceous marls and clays, calciferous grits (macigno). The whole, in short, is a lithological epitome 
of the great Permian system hereafter to be described. 
