TKACFS nr I FIF. niU'AT ICK Af.K I\ DEREVSHIKF. 2 1 



by the stream), is received by the surface of the glacier, 

 forming lines oi debris known as moraines. A vast quantity of this 

 debris finds its way down the numerous crevasses with which 

 the surface of the glacier is intersected, and, held by the ice as 

 by a vice, these angular fragments play the part of cutting tools 

 upon the bed of the glacier. Nay, they are more effective than 

 if held by a vice, for the yielding character of the ice retards 

 their breaking up. These effects may be well seen in many of 

 the Swiss valleys, notably in the Haslithal between Meiringen 

 and the Unteraar Cxlacier. A portion of the path along this 

 valley passes over bosses of rock of considerable extent which 

 have been polished as smooth as glass, and, though the angle of 

 slope is not considerable, it has been found necessary to cut steps 

 in the rock. This rounding and polishing may be observed high 

 upon the precipitous sides of the valley, proving that at one time 

 the valley was full of ice, which probably overrode all but the 

 highest peaks. It may be seen on a level with the Grimsel Pass. 



But the previous extension of a glacier is manifested by 

 another fact. The path of the river of ice is bounded by two 

 lines of debris — the lateral moraines — and, where it melts, all 

 the material brought down is deposited, forming a terminal 

 moraine. AVhere a glacier is receding, a number of terminal 

 moraines along the valley mark the stages of its shrinking. 

 Many of the blocks are grooved and striated after the manner of 

 the bed of the valley, and in a manner quite different to the 

 smoothing produced in a stream-worn boulder or pebble. Many 

 boulders however, in fact the great majority, are not marked at all 

 - it must not be forgotten that many of them have remained on 

 the upper surface of the glacier, or embedded in the ice, to the 

 end of their journey, and others are of a material which fails to 

 retain the markings for long periods. Sometimes the glacier in its 

 shrinking will leave enormous blocks perched in the most remark- 

 able manner on the sides of the valley (as may be seen to perfec- 

 tion in our own country, together with the other phenomena here 

 mentioned — in the Vale of Llanberis). It will be seen that 

 rocks may thus be transported from the very source of the ice 



