SNOW AND ICE. 
105 
They are an important factor in Alpine life. The 
amount of snow which they bring down is enormous. 
Coaz* estimates it in certain districts as equal to 
1 metre of snow over the whole district. Without them 
the higher Alps would be colder, the lower regions 
hotter and drier. The snow-line would come down 
lower, many beautiful Alps would be covered with 
perpetual snow, the glaciers would increase, the 
climate become more severe, the mountains less 
habitable. To appreciate the importance of ava- 
lanches one must ascend the mountains on a warm 
day in spring. From every cliff, in every gorge we 
hear them thundering down all round us. They 
descend on all sides like hundreds of waterfalls, 
sometimes in a silver thread, sometimes like a broad 
cataract. The mountain seems to be shaking off its 
mantle of snow. 
However destructive then they may be at times, 
avalanches are on the whole a blessing.** 
Glaciers. 
By the slow action of pressure, and the percola- 
tion of water, which freezes as it descends, the firn 
passes gradually into ice. In cool and snowy 
* Die Lawinen in den Schweizercilften , Bern, 188 1, 
** Heim, Gletsclierkunde . 
