Pioneer Labourers 27 



very hardest rocks when driven against them by the 

 former, and, when driven by water, has produced the 

 great canons, or narrow gorges some thousands of feet 

 in depth, with which we arc famihar in Cahfornia. 

 Nor will it be necessary to dwell upon the hammering, 

 battering effects of the rains, which are sufficiently 

 obvious even in our climate, and are of course greatly 

 intensified in tropical regions. 



But a few words must be said about the glaciers, 

 those frozen rivers, which are among the mightiest of 

 nature's grinders. Looking down upon a glacier, and 

 seeing it strewn with the blocks of stone and vast 

 heaps of rubbish which have fallen upon it from the 

 cliffs above, dislodged by the frost, we should be dis- 

 posed to think it a very rough labourer indeed, merely 

 engaged in carting away the wreckage made by others. 

 But this would be a great mistake. A little brawling 

 stream makes, it is true, far more noise and fuss, and 

 even more show of work, as it rolls the pebbles over in 

 the bed which it is perpetually deepening and widen- 

 ing ; but the glacier is a giant mill-stone, pressing 

 upon the rocks beneath with a power which is simply 

 irresistible. 



Glaciers move on in solemn silence, it may be at the 

 rate of perhaps only an inch or two in the twenty-four 

 hours, but they go on steadily and noiselessly, and as 

 they go, they grind the rocks beneath to a powder so 

 fine, that when at last it escapes from the glacier-mill 

 in the stream, which flows out from beneath, it has 

 been reduced to nothing but mud. 



One other grinder, equally mighty and thorough, 

 but by no means silent, must be mentioned in con- 

 clusion. This is the volcano, which, besides pouring 



