158 
ORIGIN OF THE SULPHUR DEPOSITS. 
of whitish limestone, charged with the Productus Cancrini, Avicula Kazanensis, and 
other characteristic forms. Thick bands of magnesian limestone with yellow sur- 
faces, in beds of three, lour, and five feet each, appear on the side of the hill, and 
aie oveilaid by a dolomitic tufa containing gypsum and siliceous agate-like con- 
cretions, the summit being composed of marlstone, and white limestone as expressed 
in this woodcut : 
27. 
Marlstone and white limestone. 
Gypsum, limestone, sulphur and dolomitic tufa. 
Magnesian limestone and marl. 
As sulphur was formerly extracted from these hills, we may take this opportu- 
nity of saying, that the whole of the tract between Bugulrna and Sergiefsk which 
is watered by the river Sok, has been minutely described by Pallas 1 as the seat of 
some copper ore, much gypsum, marl and limestone, with native sulphur, sulphu- 
reous and asphaltic sources and lakes. The deposits most charged with sulphur 
occur on the left bank of the Sok and around the spot now fixed upon as the site 
of the baths, but they also extend from the town of Sergiefsk to the confluence of 
the Sok with the Volga, near to which great quantities of native sulphur were 
formerly extracted from the strata, and extensive works were in activity at Sernoi- 
Gorodok. In his description of that locality, Pallas distinctly acquaints us, that 
the sulphur was regularly deposited in marly and gypseous horizontal strata, sub- 
ordinate to limestone, exactly similar to that which we are now describing at the 
baths of Sergiefsk. This circumstance, and the copious issue of highly sulphureous 
as well as asphaltic sources at many points from these rocks, which are regularly 
bedded and in a wholly unaltered condition, may have an important bearing upon 
geological theory. Viewed under one aspect only, these facts might lead us to be- 
lieve that the phsenomena were entirely unconnected with igneous or volcanic phte- 
nomena. In fact, the district of Sergiefsk is not less than 400 versts distant from 
any eruptive rock, and, as above said, the strata which contain the sulphur or emit 
the mineral waters are unbroken and unchanged. 
According to a recent examination of the sulphur deposits of Sicily, by M. Pail- 
lette, a French engineer 2 , showing that the beds in which the sulphur is contained 
1 Vol. i. French Edit. p. 142 et seq. 
* See ‘ Comptes Rendus a l’lnstitut,’ May 1843, and an able report of M. Dufrenoy. 
