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 



JANUARY 



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 



