86 
FUSULINA LIMESTONE OF THE LOWER VOLGA. 
clipping beneath the surface throughout large tracts, occupied sometimes by 
secondary and at other times by tertiary rocks, which we shall presently describe, 
this younger member of the carboniferous limestone reappears in great force on 
the right bank of the Volga, and occupies the splendid cliffs, 200 to 300 feet 
high, between Simbirsk and Samara, -which give rise to that remarkable flexure in 
the course of this monarch of European streams, which is seen on every map of 
Russia. 
At the mouth of the Ussa, and on the Volga, the beds are exposed in a fine ver- 
tical section in the following ascending order, and consist of — 
a. Thick beds of grey sandy limestone with Orthis 19 . 
resupinata ? ; and a small species associated with Fu- 
sulinse. The vertical face of this lower stratum is 
affected to a height of thirty feet by the action of the 
periodical vernal rise of the waters, the least solid por- 
tions being corroded, and other parts protruding in 
undulating depressions, and the whole polished and 
smoothed off, the highest water-mark line being very permanent 1 . 
b, c, d. White limestone of soft texture, and charged with myriads of the Fusu- 
lina cylindrica, alternating with other beds of grey and yellowish colours, more or 
less compact, of scaly conchoidal fracture, in which Euomphalus pentangulatus 
and Orthis resupinata are occasionally detected, and round concretions of very pure 
flint are not unfrequent. Corals and Encrinites also occur, and among the former 
are species of Turbinolia, Cyathophyllum, Retepora, and Fenestella, which will be 
described in the Third Part of the work. In those parts of the cliff which have 
stood firm, the surface is covered by an ochreous coloured lichen, but whenever 
the opening of the fine symmetrical joints has given rise to the fall of large masses 
of the rock, the white and grey colours are well exposed. 
e. Thinly laminated, almost papyraceous strata, with courses of a lithographic 
stone, much resembling that of Solenhofen, surmounted by bands of pure Fusulina 
limestone, from fifteen inches to four and five feet thick (Upper quarries). 
/ and g. Thin, rubbly limestones, with occasional Fusulinae and courses of chert, 
rise to the summit in a slope, and complete these sections of Fusulina rock, which 
is at least 200 feet thick. As other and higher hillocks rise to the back of this 
1 1 his phenomenon is common throughout all those parts of Russia where rocky cliffs are at hand to 
show the limits of the rise of water during the great floods of the spring. 
