THE AGE OF ICE. 



6 S 3 



tern of planets through a much warmer region than the space now en- 

 circling us. 



Centres of Dispersion.— All existing glaciers flow from higher to 

 lower levels as a rule— the only exception being that already stated, 

 when the ice may be forced up-hill for a short distance. This may be 

 well exemplified in the Alpine glaciers of the present day. These 

 streams of ice all flow from the summits and axes of particular moun- 

 tains along the valleys, and spread over the neighboring plains. The 

 action is radial— proceeding from a central point or line outward. 



Fig. 10. 



Awine Glacieb.— (H. M. Skae.) 



The geologists have concluded that most of the ancient ice-move- 

 ments in Northern Europe have been from centres of dispersion, like 

 those in Switzerland. Examples are numerous. One of the most in- 

 teresting is exhibited in Switzerland. The traveler finds there two 

 prominent centres of glacial radiation— the Bernese and the Mont 

 Blanc regions. Glaciers now flow westerly into the great valley of 

 Switzerland and toward the Rhone from the former, and in the latter 

 group the streams discharge upon the Italian plains on the south, 

 and toward the vale of Chamouni on the north. A careful study of 

 the vale of Chamouni shows that ice once filled it to the brim, for 

 the embossed rocks carry striae even to the height of 5,000 feet. 



