84 
WHITE LIMESTONE NEAR JELATMA ON THE OKA. 
One of the most remarkable outcrops of the limestone from beneath the sands 
or clays which so generally obscure the rocks of the government of Riaizan, is at 
the ancient Tartar town of Kasimof. The rock must here be of great dimensions, 
tor it rises from the level of the Oka, to plateaus at least 300 feet above it. Some 
beds are so yellow and magnesian (they lie chiefly towards the middle of the sec- 
tion), that they cannot be distinguished from specimens of zechstein, like which 
they often disintegrate into a fine powdery sand, and the lower beds, which are 
hard and white, project upon the road which descends from the town to the ferry 
over the river. 
Here we found some characteristic fossils, together with spines of the same 
species of Echini, as on the Dwina, near Archangel 1 . 
The rocks of white limestone (in this region void of alternating red marls 
and sandstones) extend from Kasimof towards Jelatma, where they are sur- 
mounted both by Jurassic strata and ferruginous sands. At the iron-works on 
the little river Unja, a tributary of the Oka, the lowest beds visible, as seen 
on the right bank of the stream, in the high road, and not far distant from the 
forge, consist of thin-bedded, concretionary, hard, flag-like beds, in parts cavernous, 
and fissured by many vertical joints. On the opposite bank, the beds, being slightly 
inclined to the east-south-east, may be followed across a low promontory, sub- 
tended by the river, in which they appear as represented in this woodcut. 
IS. 
n. Limestone, concealed. 
h. Yellowish and magnesian limestone, with thinly laminated bands of flint and ochreous argillaceous way-boards. The rock is very cavernous, and 
the cavities are often lined with corals, chiefly a large Cyathophyllum ; and among the other fossils are Orthis vximin, Produvtm comoides P. un- 
datua (Dc Fr.), P. antiquatus, Spirifer Moaqucnsis, Leptama Hurdremis, with Encrini. These beds are corroded on the surface, and their superficial 
depressions filled with iron sand are succeeded at a little distance in the cliff by a white, hard, flag-like, sandy limestone (c). The iron sands ( x ), 
which cover indiscriminately the denuded heds of limestone and the drift (y), will be described in subsequent chapters. 
As the carboniferous limestone is succeeded in a very short space by Jurassic 
strata, which are clearly exposed on the banks of the Oka, near the adjacent 
town of Yelatma, and as all the region to the south is occupied by cretaceous or 
1 Kasimof is a very picturesque town, and the Oka is there a magnificent stream. Any traveller would 
be well repaid by visiting a spot so celebrated in Russian history, and in which a very ancient tower and 
mosque of the Tartars are still to be seen among the gay churches of their conquerors. 
