268 
CRETACEOUS ROCKS OF KURSK. 
what Major Blode has designated “ Kiesel-thon.” We consider it, however, to be 
of the Cretaceous epoch, for the following reasons. Three or four versts to the east 
of Kharkof, these white rocks are overlaid by regularly bedded, ferruginous sands, 
sometimes almost flagstones, but in other parts appearing as concretions in fox- 
coloured sand. Such beds occur in certain ravines, where a passage is seen into 
the whiter masses through strata of green sandstone, in which grains of chlorite 
are disseminated in a sandy argillaceous paste. Being the only hard beds in the 
country, they are much used for building and paving purposes. 
These rocks, extending to the northern frontiers of the government of Kharkof, 
offered us no organic remains, nor has Major Blode, who has examined them much 
more than ourselves, been able to detect any traces of such, even where they range 
over a wide space westwards into the government of Pultava. In that direction 
indeed, the hard ferruginous masses often form isolated hills. At Bielgorod, about 
sixty versts to the north of Kharkof 1 , a mass of true chalk reappears high above 
the town, and therefore, as we conceive, overlying some members of the great 
arenaceous development of the Cretaceous system which we detected under the 
drift, in the lower slopes of the adjacent hills. The ascending section here, in 
proceeding from the valley to the hill above the town upon the north, exhibits — 
1. Sands, &c. ; relations obscured in the slopes. 2. White chalk without flints, in 
horizontal beds about 100 feet thick. 3. Greenish friable sandstone, about ten 
feet, containing siliceous flags, and separated from the chalk by a course of gray 
laminated marl. 4. Superficial black earth or “ Tchornozem.” 
At Oboyan on the river Psol, the white chalk disappears, and the cliffs have ex- 
actly the same appearance as those near Kharkof ; for what seemed to us to be 
chalk under the first rays of an autumnal rising sun, proved on closer inspection 
to be non-calcareous, and nothing more than a white variety of the “ Kiesel-thon,” 
or sandy marlstone, in which a very little calcareous matter was disseminated ; and 
thus the rock began to assume the real characters of the upper greensand, the 
Planer-kalk of Germany, or the “ Malm rock ” of England. At the stage north 
of Oboyan, called Selikof, rocks of the same general aspect become still more cal- 
careous, and exhibit strata (in the ravines) which show a distinct passage from dirty 
white, sandy, argillaceous marl, to chalk marl, — and even into what could not be 
distinguished, at first sight, from chalk, but which in reality, however, is not so, 
as is well known to the natives, who transport their “ meol” or true chalk from a 
distance of forty or fifty versts. It may be remarked, that in proportion as these 
1 The White City. 
