98 ICE AND GLACIERS. 



habits, apart from the dazzling of his eyes, which he must pro- 

 tect by dark spectacles or by a veil, usually gets severely sun- 

 burnt in the face and hands, the result of which is an inflam- 

 matory swelling of the skin and great blisters on the surface. 

 More pleasant testimonies to the power of the sunshine are the 

 vivid colours and the powerful odour of the small Alpine flowers 

 which bloom in the sheltered rocky clefts among the snow-fields. 

 Notwithstanding the powerful radiation of the sun the tempera- 

 ture of the air above the snow-fields only rises to 5, or at most 

 8 ; this, however, is sufficient to melt a tolerable amount of the 

 superficial layers of snow. But the warm hours and days are 

 too short to overpower the great masses of snow which have 

 fallen during colder times. Hence the height of the snow-line 

 does not depend merely on the temperature of the mountain 

 slope, but also essentially on the amount of the yearly snow- 

 fall. It is lower, for instance, on the moist and warm south 

 slope of the Himalayas than on the far colder but also far drier 

 north slope of the same mountain. Corresponding to the moist 

 climate of western Europe, the snow-fall upon the Alps is very 

 great, and hence the number and extent of their glaciers are 

 comparatively considerable, so that few mountains of the earth 

 can be compared with them in this respect. Such a develop- 

 ment of the glacial world is, as far as we know, met with only 

 on the Himalayas, favoured by the greater height; in Greenland 

 and in Northern Norway, owing to the colder climate ; in a few 

 islands in Iceland ; and in New Zealand, from the more abun- 

 dant moisture. 



Places above the snow-line are thus characterised by the 

 fact that the snow which in the course of the year falls on its 

 surface does not quite melt away in summer, but remains to 

 some extent. This snow, which one summer has left, is pro- 

 tected from the further action of the sun's heat by the fresh 

 quantities that fall upon it during the next autumn, winter, and 

 spring. Of this new snow also next summer leaves some 

 remains, and thus year by year fresh layers of snow are accu- 

 mulated one above the other. In those places where such an 

 accumulation of snow ends in a steep precipice, and its inner 



