24. Sketch of the Geology of Northern Russia. 
The salt steppe is a remarkable region lying at an extremely low 
and uniform level, occasioned it is believed, by a change in the level 
of the Black Sea. Pallas, and others who have examined the geolo- 
-gy of this tract, conjecture that the waters of the Black Sea, at some 
remote period, burst a passage through the straits of Constantinople, 
and receding from this shallow tract, left it dry, from its present mar- 
gin to the shores of the Caspian. This supposition is rendered highly 
probable, from the extreme want of fresh water through the whole 
extent of the steppe, and the fact of its being covered with sand, 
and recent shells like those now found in the neighboring seas, with 
no other herbage upon its whole surface, than an occasional tuft of 
such plants as grow only on the sea shore. Lakes and pools are 
found in its different sections and an efflorescence of salt, resembling 
hoar frost is said to cover some parts of the dry ground. The rock 
under the sandy superficies is a hard black dry slate, sometimes 
bare and totally sterile. The whole steppe is a tract of barren desert 
without inhabitants. 
In the centre of this steppe, alabaster, which is said to belong to 
the salt formation, rises in the insulated hills of limestone, accompa- 
nied with gypsum and salt. 
The Caucasian chain consists chiefly of primitive rocks, but in 
many parts of columnar trap. The secondary rocks resting on its 
northern border, are a continuation of the mountains of the Crimea, 
and consist principally of slates and limestone, with chalk and flints. 
On the south part of the secondary tract is a soft shelly yellowish 
limestone, extending along the shores of the Black Sea, through a 
rich and productive, although a woodless, country. 'The secondary 
strata, being probably a continuation of these limestones, form the 
high steppe of Pallas, between the lower Volga and the Don. 
VIII. Miscetnansous Novices or Srperta. 
Geological inquiry has made but little progress in the northern re- 
gions of Asia, but a miscellaneous notice of Siberia, is subjoined, 
enumerating such mineral and metallic substances, as are known to 
occur, although their positions in situ are not ascertained, nor m 
every instance their localities. This immense territory extending 
from the Ural mountains on the west, to the Pacific Ocean on the 
east, and from the borders of China and Kalmuck Tartary on the 
south, to the Frozen Ocean, presents a scene of great interest to the 
