THE TUNDRA AND ITS FAUNA 17 



The precipitation is everywhere small, except in the 

 south-western extremity of Greenland. Elsewhere the 

 mean never exceeds 10" per annum, and may be much 

 less. The winters especially are remarkable for the 

 clearness and dryness of the atmosphere and the 

 virtual absence of precipitation. The result is that, 

 contrary to what might be expected, the snow does not 

 form everywhere a thick mantle, and the frequency of 

 strong winds helps to diminish its thickness in places, 

 a fact which greatly aids the obtaining of food by 

 such herbivorous mammals as the reindeer and musk- 

 ox. During the short summer precipitation is frequent, 

 though slight, and fog and mist are common. The sub- 

 soil is permanently frozen, and there is thus no ground 

 water. This renders all erosion mechanical, and as 

 springs are absent the rivers are fed only by the melt- 

 ing of ice and snow, and are temporary, being frost- 

 bound in winter. 



There are only two seasons — winter and summer — 

 and the winter extends far into the months which are 

 spring elsewhere, so that March or even April may be 

 the coldest month. It is apparently these months which 

 take the largest toll of animal life, for Nordenskiold 

 notes that the reindeer are in better condition in the 

 depth of winter than in the spring months. Summer 

 comes with extraordinary rapidity, and with its coming 

 life suddenly bursts into activity. Thus all the flowers 

 bloom at once, giving rise to the local luxuriance 

 noticed by many explorers. The rapidity of develop- 

 ment is of course aided by the virtually continuous 

 daylight. As the rays of sunlight have a very oblique 

 direction, local conditions count for much in promoting 

 the growth of plants, and therefore the occurrence of 

 land animals. Thus a slope where the ice-cold water 



1404 B 



