IN CLOUDS AND RIVERS, ICE AND GLACIERS. 



97 



crumbling crests, with crevasses right and 

 left. The confusion increases until further 

 advance along the centre of the glacier is im- 

 possible. 



121. But with the aid of an axe to cut 

 steps in the steeper ice- walls and slopes we 

 might, by swerving to cither side of the 

 glacier, work our way to the top of tne cas- 

 cade. If we ascended to the right, we should 

 have to take care of the ice avalanches which 

 sometimes thunder down the slopes ; if to the 

 left, we should have to take care of the stones 

 let loose from the Aiguille Noire. After we 

 had cleared the cascade, we should have to 

 beware for a time of the crevasses, which for 

 some distance above the fall yawn terribly. 

 But by caution we could get round them, and 

 sometimes cross them by bridges of snow. 

 Here the skill and knowledge to be acquired 

 only by long practice come into play ; and 

 here also the use of the Alpine rope suggests 

 itself. For not only are the snow-bridges 

 often frail, but whole crevasses are some- 

 times covered, the unhappy traveller being 

 first made aware of their existence by the 

 snow breaking under his feet. Many lives 

 have thus been lost, and some quite re- 

 cently. 



122. Once upon the plateau above the ice- 

 fall we find the surface totally changed. Be- 

 low the fall we walked upon ice ; here we are 

 upon snow. After a gentle but long ascent 

 we reach a depression of (he ridge which 

 hounds the snow-fild at the top, and now 

 iook over Italy. We stand upon the famous 

 Col du Geant. 



123. They were no idle soimpcrcrs on the 

 mountains that made these wild recesses first 

 Known ; it was not the desire for health 

 which now brings some, or the desire for 

 grandeur and beauty which brings others, or 

 the wish to be able to say that they have 

 climbed a mountain or crossed a col, which 

 I ft'ar brings a good many more ; it was a 

 desire for knowledge that brought the first ex- 

 plorers here, and on this col the celebrated 

 De Saussurc lived for seventeen days, mak- 

 ing scientific observations. 



15. QUESTIONING THE GLACIERS. 



124. I would now ask you to consider for 

 a moment the facts which such an excur- 

 sion places in our possession. The snow 

 through which we have in idea trudged is 

 iihe snow of last winter and spring. Had we 

 placed last August a proper mark upon the 

 surface of the snow, we should find it this 

 August at a certain depth beneath the sur- 

 fMce. A good deal has been melted by the 

 summer sun, but a good dual of it remains, 

 and it will continue until the snows of the 

 coming winter fall and cover it. This again 

 will be in part preserved till next August, a 

 good deal of it remaining until it is covered 

 by the snow of the subsequent winter. We 

 thus arrive at the certain conclusion that on 

 the plateau of the Col du Geant the quantity 

 of snow that falls annually e.vcmt* the, quan- 

 tity melted. 



125. Had we conic in the month of April 



or May, we should have found the glacier be- 

 low the ice fall also covered with snow, 

 which is now entirely cleared away by the 

 heat of summer. Nay, more, the ice there 

 is obviously melting, forming running brooks 

 w T hich cut channels in the ice, and expand 

 here and there into small blue-green lakes. 

 Hence you conclude with certainty that be- 

 low the ice-fall the quantify of frozen material 

 failing upon the (/lacier is leas than the quan- 

 tity melted. 



126. And this forces upon us another con- 

 clusion ; between the glacier below the ice- 

 fall and the plateau above it there must exist 

 a line where the quantity of snow which falls 

 is exactly equal to the quantity annually 

 melted. This is the snow-line. On some 

 glaciers it is quite distinct, and it woidd be 

 distinct here were the ice less broken and 

 confused than it actually is. 



127. The French term neve is applied to 

 the glacial region above the snow-line, while 

 the word glacier is restricted to the ice below 

 it. Thus the SUDWS of the Col du Gant 

 constitute the nev6 of the Glacier du Geant, 

 and in part, the neve of the Mer de Glace. 



128. But if every year thus leaves a resi- 

 due of snow upon the plateau of the Col du 

 Geant, it necessarily follows that the plateau 

 must get annually higher, provided the snow 

 remain upon it. Equally certain is the con- 

 clusion that the whole length of the glacier 

 below the cascade must sink gradually lowei , 

 if the waste of annual melting be not made- 

 good. Supposing two feet of snow a year to 

 remain upon the Col, this would raise it to & 

 height far surpassing that of Mont Blanc in 

 five thousand years. Such accumulation, 

 must take place if the snow remain upon the 

 Col ; but the accumulation does not take 

 place, hence the snow does not remain on 

 the Col. The question then is, Whither does 

 it go? 



16. BRANCHES AND MEDIAL MORAINES 



OF THE MER DE GLACE FROM THE CLEFT 



STATION. 



1.29. We shall grapple with this question 

 immediately. Meanwhile look at that ice- 

 valley in fiont of us, stretching up between 

 Mont Tacul and the Aiguille de Lechaud, 

 to the base of the great ridge called the 

 Grande Jorasse. This is called the Glacier 

 de Lechaud. It receives t*t its head the 

 snows of the Jorasse and of Mont Mallet, 

 and joins the Glacier du Geunt at the prom- 

 ontory of the Tacul. The glacieis seem 

 welded together where they join, but they 

 continue distinct. Between them you clearly 

 trace a stripe of debris (c on the annexed 

 sketch-plan) ; you trace a similar though 

 smaller stripe (a on the sketch) from the 

 junction of the Glacier du Gaunt with the 

 Glacur des Periades at the foot of the Ai- 

 guille Noire, which you also follow along 

 the Mer de Glace. 



130. We also see another glacier, or a portion 

 of it, to the left, falling apparently in broken 

 fragments through a narrow gorge (Cascade 

 dif Talefre on the sketch) and joining the 



