6 



ASIA 



shores of the mainland of North America : one would 

 therefore expect to see a correspondingly greater ex- 

 tension inland of the cold treeless desert called the 

 tundra. As a fact, however, it is not so ; the barren 

 grounds of North America reach much farther south, 

 especially towards the extreme east and west, and when 



Fig. 4. Mean Temperature of Asia in January reduced to Sea-level. 



the coast-line advances poleward or retreats southward, 

 the accompanying belt of tundra follows the same oscilla- 

 tions. This broad fringe covers a low-lying undulated 

 land, interrupted by no high hills, but indented by wide 

 estuaries and marshy deltas. 



Two main forms of tundra are recognized, the moss 



