VEGETATION DEPENDENT ON RAIN 277 



Northwards the character of the desert exhibits a 

 marked chanre. The bare sand-drifts which cover 



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so vast an expanse of the Urute country soon termi- 

 nate ; ^ and in their place we find a clay soil covered 

 with pebbles. But the topography continues the 

 same ; level or slightly undulating plains studded 

 with low hills, now connected in low ridges, now 

 standing in isolated groups, composed of silicious 

 slate, gneiss, and some of the later igneous rocks. 

 There is scarcely any vegetation, and indeed it is 

 also scanty on the plains. Wherever the soil is 

 saline the karmyk and budarhana appear, as in the 

 former tract, and where it improves a little, scrub 

 wormwood and onion are most conspicuous, the 

 latter being characteristic of this region, together 

 with the dirisun and a few more of the Gi'aminecB 

 composing the flora of the desert. Vegetation, how- 

 ever, is in every part of the Gobi mainly dependent 

 on rains ; for no sooner have these fallen, and the 

 sun's rays exerted their influence, than the young 

 plants shoot up with a rapidity Avhich compensates 

 for their long period of inactivity. Green oases 

 quickly manifest themselves where all was desert ; 

 the dzei^en appears, the loud song of the Mongol 

 lark is heard ; the inhabitants remove hither, and 

 the favoured spot teems with life in the midst of 

 surroundino- desolation. But how brief a time it 



О 



lasts ! The powerful sun gradually evaporates all 



' I should mention, however, that sand-drifts occur sporadically 

 in all parts of the Gobi, but are less continuous here than in Ala-shan 

 and the conterminous Urute country. 



