608 SCIENTIFIC RECREATIONS. 



we can see the Mer de Glace all broken and contorted. The frequently 

 occurring roar of a falling rock which heat has deprived of its icy support, 

 or the cracking and tumbling of ice-blocks, may be seen and heard in the 

 forenoon. But the grandeur and majesty of the ice and snow-clad mountains 

 is best enjoyed by moonlight. 



On the ice we shall see huge stones and gravel and grit, which have 

 been carried down by the ever-moving glacier, which is denuded in its 

 course, and worn down upon the surface as it slides, scraping and grinding 

 the valley through which it flows. By passing along a path now made easy 

 by irons, but formerly without supports or guards, the surface of the glacier 

 will be reached, and a man with a hatchet will cut steps for the timid 

 traveller. We are now upon the deep ice river, which has its springs in the 

 snowy regions of the Col de Geant, in the snow which is continually falling 

 upon the heights, and draining away to water again to form a river. 



Thus the circle of events is completed, snow, neve, ice (glacier), water r 



which last is again absorbed into the atmosphere, and again descends as 



___ ^^ -- ^__ ram or snow - And this is 



always going on by the action 

 of the sun. It may here 

 fairly be asked how snow be- 

 comes ice. Why does not the 

 snow turn into ice at once, 

 and form a glacier at the 

 top of the mountain as well 

 as at the bottom ? We will 

 endeavour to make this clear. 

 Snow is composed of crystals, 



Fig. 605. Glacier table. J 



which assume certain definite 



forms, and when first the flakes fall they are soft and powdery. By degrees 

 they melt a little, and when unconsolidated form what is termed neve, the 

 border line between ice and snow. This semi-icy snow descends under pressure, 

 and, as it increases, the glacier is formed by huge blocks and masses being 

 pressed together on the steep slopes of the mountains. Thus the glacier de- 

 scends, rounding off rocks, and scouring as it goes, moving at a certain 

 estimated rate daily, about twenty inches on the average, carrying stones 

 and debris which form the moraine, and finally when the high temperature in 

 the valley melts the ice, it issues forth as a river into the plain, or bounds 

 down the mountain side in a cascade. An excursion and one by no means 

 dangerous if a guide be taken to the Jardin, near Chamouni, will reveal 

 many interesting features of glacier formation, and of the glaciers themselves. 

 Physical Geography is therefore very much indebted to the action of 

 water as a fluid or as a solid. In the former condition it erodes the rocks, 

 carries down the stones and gravel and sand, forms deltas at the mouths of 

 rivers, and elevates plains by overflowing its banks and depositing sedi- 

 ment. Water gives beautiful scenery, 'and the ever-changing features of the 



