RED CONGLOMERATE AT THE BASE OF THE CARBONIFEROUS SYSTEM. 93 
these deposits, from which we might dev elope a true ascending order. Whether 
we referred to the Russian authors who had described the country, or toM. LePlay, 
who was preparing an account of it, we were met on all sides with the statement, 
that, owing to the convolutions of the strata and the want of fixed mineral cha- 
racters, no regular order could be established. To geologists, therefore, who like 
ourselves were thrown into a new field, in which the succession of the beds was 
perfectly unknown to us, nothing could be more satisfactory than to find, in one 
of the first sections which we made, a key to the whole order of this country, and 
by which we established that the most ancient strata occupy the southern zone of 
this carboniferous region. 
Of Silurian or true Devonian rocks we could perceive no traces. Immediately, 
however, to the north of the crystalline rocks at Karakuba and on the right bank 
of the Kalmiuss, we discovered a red sandstone and shale with some conglomerate, 
which is so loaded with fragments of porphyry, that it seems in parts almost to 
pass into that rock, upon which it may be said to rest '. 
The lower grounds and slopes are there occupied by these red strata, which are 
laid open in ravines, and are distinctly overlaid by the carboniferous limestone at 
heights of 200 to 300 feet above the valley. 
As this undulating and diversified tract differs essentially from the countries of 
Northern and Central Russia, in exhibiting within comparatively short distances 
both numerous flexures and the most decided changes in the succession of strata, 
we have illustrated it with the opposite plate of coloured sections (see PI. I. fig. 1, 
and also the general section below the Map). 
In some of its lower beds this sandstone is argillaceous, of grey and green, as 
well as red colours, and towards its upper limits becomes more and more a con- 
glomerate ; the pebbles, varying from a small size to that of pears, consist chiefly 
of the felspathic and quartzose rocks before described, lumps of pink, felspar 
porphyry particularly abounding. The ascending section, as far as our short ex- 
amination enabled us to detect it, consists of greyish coarse grits and alternations of 
purplish red and green sandy shale, partly micaceous, with strong bands of greyish 
quartzose grit, in parts a pebble rock, with false bedding. Silicified or sandy casts 
of plants (apparently Stigmariee) occur in the uppermost of these strata. Red and 
1 Through the kindness of General Tcheffkine, who had in fact provided us with every document at 
the disposal of the Corps of Mines which could throw light upon our inquiries, we were furnished with 
a map of this tract by Colonel Olivieri, on which this porphyry was laid down. 
O 
