48 NATURAL HISTORY OF 



the Elburs chain, entirely surrounded by saline plains 

 of hard clay, and low sandy steppes ; on the west, 

 extended to the Sea of Azoph and the Euxine, and 

 between the Kama, Don, Wolga, Jaik, Lake Aksakal, 

 the lower Ichim, and the Amoo, covering a space of 

 18,000 square leagues. In addition to the inland seas 

 already mentioned, on the south-east, is the desert of 

 Karakoum, or of black sand, estimated, alone, at 150 

 miles in length by 100 in breadth, forming a plain 

 without a tree, the floor of an evaporated and perco- 

 lated sea. 



With the exception of the Oulon-tag, the Ildiglis, 

 and the low Monghogar hills, the surface extends north- 

 eastward, with scarcely an undulation. It is studded, 

 in all directions, with smaller lakes, sedgy pools, mo- 

 rasses, and temporary rivers, which now terminate in 

 small water basins, or are lost in the sand ; and the 

 occasional more elevated spaces are always edged by 

 water-worn indications. The vast lake, which for- 

 merly covered a great space on the south of Khiva, 

 in long. 59, lat. 41 15", has disappeared all but a 

 few pools, where the whole region is intersected with 

 vestiges of ancient canals of irrigation, now dried up. 

 These show a second stage or era, when the sea had 

 departed, and rivers still flowed onwards to the Cas- 

 pian. So also the Kirguise steppe, forming the nor- 

 thern portion of the depressed region, is composed of a 

 cold clay, which notwithstanding, was anciently pro- 

 ductive of a remunerating income to the cultivator ; 

 but husbandry continuing to be invaded by a black sea 



