CHARACTERISTICS AND DISTRIBUTION OF LAKES 531 
whole south-east of Russia in Europe by such important rivers as 
the Volga and the Ural, but it has no outlet. So large is the mass 
of fresh water poured into it, that the greater part of the lake- water 
is less salt than that of the ocean, but the results of evaporation 
are seen in its being relatively more sulphatic. The amount of 
water supplied to the Caspian balances that lost by evaporation ; 
nevertheless, along the shore in summer much evaporation goes 
on in lagoons, and the Gulf of Karaboghaz on the east shore 
may be regarded as a huge evaporating basin, 7500 square miles in 
area. It is no more than 50 feet in depth, and is connected with 
the main basin of the Caspian by a channel about 150 yards wide and 
5 feet deep. It has been proposed to dam the strait in order to raise 
the level of the Caspian and to increase its salinity. The Gulf is 
situated in a warm region, and loses so much water by evaporation 
that its level is always lower than that of the Caspian. Conse- 
quently a current from the latter is continually flowing in, while 
there is no compensating under-current outwards. The salinity 
of the water is about 16 per cent., and Baer^ estimated that 350,000 
tons of salt were carried in daily ; fish which enter the Karaboghaz 
from the Caspian are killed and naturally salted, and, it is said, 
supply food to the wandering tribes along its shores, who dig them 
out of the precipitated salt. The bottom of the Gulf is flat, and is 
covered in the central part over an area of about 1300 square miles 
by a bed of sodium sulphate (Glauber's salt), while in other parts 
calcium sulphate (gypsum) and mud are found. 
It appears from the researches of Filippoff that during the years 
1851-88 the level of the Caspian thrice stood at a maximum, the total 
range of the oscillations being 3 J feet. Besides these changes, there 
are also the seasonal ones (lowest level in January, highest in summer). 
Observations were made in 1904 by means of the Ekman apparatus 
on the currents in the Caspian, and showed that in the northern 
part there is a surface current flowing along the west coast towards 
the south ; in the central part the current takes the same direc- 
tion ; sweeping round the southern shore, the current returns to 
the north along the eastern coast, almost to the peninsula of 
Manguichlague, where it deviates to the west to join that on the 
Caucasian coast. 
Life, with the exception of bacteria, is absent in the deepest parts 
of the Caspian Sea. An oligochaete worm was got at a depth of about 
1300 feet, but below that is an abyssal area totally destitute of life. 
This is due, not as in the case of the Black Sea to the presence of 
hydrogen sulphide, but to the scarcity of oxygen in the deep layers 
arresting the development of life. About 64 per cent, of the fauna 
^ Cited by Geikie, op. cit., p. 383. 
