ICE AND GLACIERS. 



113 



clear blue gateway of ice, out at the lower end of the 

 larger glacier. 



On the surface of the ice there is a large quantity of 

 blocks of stone, and of rocky debris, which at the lower 

 end of the glacier are heaped up and form immense walls ; 

 these are called the lateral and terminal moraine of the 

 glacier. Other heaps of rock, the central moraine, stretch 

 a'ong the surface of the glacier in the direction of its 



FIG. 13. 



length, forming long regular dark lines. These always 

 start from the places where two glacier streams coincide 

 and unite. The central moraines are in such places to be 

 regarded as the continuations of the united lateral 

 moraines of the two glaciers. 



The formation of the central moraine is well represented 

 in the view above given of the Unteraar Glacier. Fig. 1 3. 



