22 Address of Sir R. I. Murchison 
there existed in the latest tertiary, or what some call quater- 
nary times, a vast depression on the surface of the globe, ex- 
tending over 8,000 square marine leagues, in which a great in- 
land sea was accumulated, and which, ina work on Russia, 
my associates and myself first mapped out under Humboldt’s 
name of Aralo-Caspian.* In that sea there lived an eek 
ance of molluscous and other animals, all of species having a 
local and limited range, and all strikingly distinguished from 
the more numerous animals of oceanic seas. No Ww, owing to 
the upheaval of large portions of the bottom of that old in- 
land sea, its animal contents formed, ina fossil state, the 
Steppe limestone, are seen at different levels over an enormous 
area, Owing to these pre-historic movements of the crust of 
the earth, eee fossil remains are seen to occupy the strata 
on the banks of the lake of Aral, as well as on the shores of 
the Caspian Sea. They also occur at various places and at 
different heights in the adjacent Steppes, extending westward 
to the country of the Don Cossacks to the north of the Sea of 
Azof, where I have myself examined them. There is therefore 
of alavation that part of the former great sea which be 
e Aral was elevated to about 117 ft. above the former a 
ern part, or present Caspian, and the seas thus insulated were 
separated t h the same movements by the élevated plateau 
now called Ust-Urt 
Sd the physical condition of the region long before 
tradition orhistory, Humboldt has well remarked that the 
great Aralo-Caspian depression had a similar origin to the 
much deeper cavity in the earth’s surface occupied by the Dead 
_ Sea, though the one is only 83 feet and the other nearly 1300 
feet beneath the Ocean. Now, if we endeavor to account 
| tically for the low present level of the old Aralo-Caspian 
. Sea by evaporation only, we are met by the facts that large 
. portions of its former bottom have been raised to different al- 
* See ‘ Russia in Europe and the Ural Mountains,’ vol. i, 303-314, and par- 
observe the map and. , p- 311, from a aes the 
Cp ands et Gt tao 
ie 
