1882.] 
373 
[Davis. 
the country, the escaping drainage is sluggish, or is entirely 
stopped, so that the lakes are destroyed very slowly. The allu- 
vial plain of China has several large lakes and many smaller ones 
that presumably belong here, or perhaps partly with the preced- 
ing species. Others occur on the steppes, east of the Ural Moun- 
tains ; among these there are fresh and salt pools in the same 
district, the occurrence of which is explained 1 by finding, at a few 
feet below the surface of the flat country, a continual oozing pas- 
sage of fresh water and by supposing that, as this has access to or 
is shut out from the pools, they are fresh or salt. Many small 
lakes in North Germany are of this origin, but still more are 
dependent on hollows of drift whose deposit was connected with 
the glacial period (C. 13). 
Second, an interior basin may be drained by the erosion or 
breaking down of its outlet ; and although the surface thus grad- 
ually disclosed is level to the eye, its inequalities are detected by 
water seeking its own level. The ponds in the flat basin of the 
Theiss in Central Hungary are probably of this origin. Lake 
Walar in the Valley of Kashmir stands in the least-filled, middle 
point of the old orograjihic basin; it is only fourteen feet deep, 
though ten by six miles in size. 2 
Some insignificant ponds in the Ohio prairies may be of similar 
origin : here the sheet of water in which the surface strata accu- 
mulated was jiresumably upheld by an ice barrier, whose melting 
allowed a drainage outlet to be formed ; very possibly other gla- 
cial conditions may have aided the production of the ponds. 
Third, many interior basins have recently been laid dry by 
evaporation, as explained under our first species ; and under this 
subdivision come the numerous pools of southern Russia, and the 
district about the Caspian and Aral. 3 Indeed, in nearly all Great 
Basins the existing lakes belong under this heading, for they 
stand as a rule upon the strata laid down by their great ancestors, 
and do not reach the mountain rock which encloses their basins. 
These lakes may be either fresh or salt ; the fresh ones drain into 
1 C. Schmidt, St. Pdt. Acad. Mdm., xx, 1873, 4, quoting Middendorff. 
2 Drew, Juraraoo and Kashmir, 166. 
3 Humboldt, Asie Centrale. n, 138, J. Sporer, Die See’nzone des Balkasch-Ala-Kul, 
Peterm. Geogr. Mittheil, 1868, 63, etc. 
