FUSULINA LIMESTONE OF THE LOWER VOLGA. 
87 
cliff, which, owing to tempestuous weather we were prevented from examining, it 
is probable that the ascending series may be better traced by those who succeed 
us, and who may detect a passage into newer deposits. 
Pallas, with his usual perspicuity, notices this singular limestone of the Volga 
and speaks of the Fusulinre as small Madreporites resembling grains of wheat, but 
he gives no sections of the strata, nor could he in his day have spoken of their 
geological relations, for our science was then unknown. There now seems no 
reason to doubt, that the Fusulina is a foraminifer, closely allied to the Alveolina 
(D’Orbigny), and as countless millions must have succeeded each other when 
these finely laminated strata were accumulated, we would now merely remark, that 
their method of conservation is a strong proof of the very tranquil condition of 
the sea in which they were deposited. 
The limestone we have been describing is capped in some parts of this remark- 
able promontory, particularly near Usolie 1 , by a tufaceous agglomerate, made up in 
great part of the limestone itself, which is probably a part of the great Permian 
system, to be described as occupying large tracts east of the Volga, in the govern- 
ments of Kasan, Perm and Orenburg. In following, however, the river to Sysran, 
the Fusulina limestone is covered by dark-coloured Jurassic shale containing 
Ammonites. The sequence of the strata on the western side of this tract is, in 
fact, interrupted, and those members of the geological series which exist in some 
other parts of Russia, between the carboniferous limestone and the Jurassic 
system, are here absent, as at Moscow (see p. 80). 
In concluding our account of the carboniferous limestone of Northern and Cen- 
tral Russia, we may repeat, that we consider the Fusulina limestone to constitute 
its uppermost member, being invariably found near the southern and eastern 
frontier of the formation, where it is succeeded by rocks of the age of the Zech- 
stein (see Map). Thus in the northern tracts, extending from the south ot Vitegra 
to the Dwina, Fusulinse have been noticed at Perkina and Filosofskaya, in the inte- 
rior at Velikovo, and upon the Ussa, as just described. Fischer has noticed 
these fossils in the government of Vladimir, we observed them in limestone to the 
north of Murom, and in the sequel we shall advert to them, both on the western 
1 Usolie is the property of M. Davidoff, who has constructed a tower and pleasure-house on the summit 
of this tufaceous rock, commanding extensive and splendid views of the windings of the V olga ; flanked 
on one side by the lofty cliffs of limestone, on which the tower of Peter the Great is placed, and on the 
other by the low and wide expanse which extends into the governments of Kazan and Orenburg. 
N 2 
