192 
SALIFEROUS ROCKS OF THE SOUTHERN STEPPES. 
cooled still lower under such circumstances, besides that some heat may also be absorbed by its ex- 
pansion. De Saussure, in a calcareous cave, found, June 29, 1771, the external thermometer 7 9 A 0 
Fahrenheit, while that in the cave was but 37| : °; and as this was in Italy, I think we may assume that a 
much greater depression would have been produced had the climate been like that of Orenburg. Whatever 
you may think of my attempt at explanation, it is at least to be hoped that your Russian friends will ere 
long obtain for you the necessary data as to climate and conduction, without which we are but guessing 
in the dark. A couple of thermometers sunk in the ground, and a journal of the state of the cave, seem 
especially necessary.” 
Ingenious as are the explanations of Sir John Herschel and Dr. Robinson, we 
still think that they do not completely solve the problem. Some persons have, 
indeed, thought that very different explanations might be proposed, by reference 
to the artificial production of ice and snow, one very remarkable example of which 
occurs in the mines of Schemnitz in Hungary'. But we are not yet sufficiently 
acquainted with all the features of the case of Uletzkaya, and apologizing to our 
two distinguished friends for having drawn forth their opinions before such data 
had been got together, we pass to other subjects, in expressing our hope, that the 
Russian authorities will soon procure for us the knowledge of the facts, without 
which no accurate induction can be made. 
Saliferous Rocks and overlying fossiliferous Limestone of the Southern Steppes . — 
In the lower steppes adjacent to the Caspian, or in that wide expanse which we shall 
afterwards describe, as having a surface covered with sea-shells, the older rocks 
similar to those of Uletzkaya rise to the surface like small islands. These islets 
are composed of red sand, marl, gypsum and limestone. Saliferous sources also 
rise to the surface at their feet, and occasion the formation of adjacent salt lakes 
and saline incrustations — even forming deposits of rock-salt in some of the deeper 
depressions. 
As examples of these isolated hills we may cite Mount Indersk and its associated 
salt lake, the gypseous elevations near Gourieff, the saliferous hills of Arsagar, the 
Great and Little Bogdo, and the gorges of red grit from which the salt rivulet flows, 
which supplies the Lake Elton, so useful to Russia as a great storehouse of salt 1 2 . 
The Indersk Hills, which we did not visit, extend for about forty versts along the 
left bank of the river Ural, and are composed, like all the other hillocks which 
emerge from beneath the steppes of Astrakhan, of gypsum, marl and sandstone 
with saliferous springs. Near the lake of the same name, Pallas also remarked 
1 See Ure’s Dictionary of Chemistry, 2nd edit., p. 290. Art. ‘ Caloric.’ 
* For an account of the source of Lake Elton, consult the Researches of M. Gdbel the chemist. 
