IN CLOUDS AND RIVERS, ICE AND GLACIERS. 



H)7 



81. SLIDING AND FLOWING. HAKD ICE 

 AND SOFT ICE. 



218. We have thus far confined ourselves 

 to the measurement and discussion of glacier 

 motion ; but in our excursions we have no- 

 ticed many things besides. Here and there, 

 where the ice has retreated fiom the moun- 

 tain side, we have seen the rocks fluted, 

 scored, and polished ; thus proving that the 

 .ice had slidden over them and ground them 

 'down. At the source of the Arveiron we 

 noticed the water rushing from beneath the 

 glacier charged with fine matter. All glacier 

 rivers are similarly charged. The Rhone 

 carries its load of matter into the Lake of 

 Geneva ; the rush of the river is here ar- 

 rested, the matter subsides, and the Rhone 

 quits the lake clear and blue. The Lake of 

 Geneva, and many other Swiss lakes, are in 

 part filled up with this matter, and will, in 

 all probability, finally be obliterated by it. 



219. One portion of the motion of a glacier 

 is due to this bodily sliding of the mass over 

 its bed. 



220. We have seen in our journeys over 

 the glacier streams formed by tiie melting of 

 the ice, and escaping through cracks and 

 crevasses to the bed of the glacier. The fmc 

 matter ground down is thus washed away ; 

 the bed is kept lubricated, and the sliding of 

 the ice rendered more easy than it would 

 otherwise be. 



221. As a skater also you know how much 

 ice is weakened by a thaw. Before it actu- 

 ally melts it becomes rotten and unsafe 

 Test such ice with your penknife : you cau 

 dig the blade readily into if, or cut the ice 

 with ease Try good sound ice in the same 

 way : you find it much more resistant. The 

 one, indeed, resembles soft chalk ; the other 

 hard stone. 



222. Now the ]\Icr ib Glace in summer is 

 in this thawing condition. Its ice is rendered 

 soft and yielding by the sun ; its motion is 

 thereby facilitated. AVe have seen that not 

 only docs the glacier slide over its bed, but 

 that the upper layers slide over the under 

 ones, and that the centre slides past the sides. 

 The softer and more yielding the ice is, the 

 more free will be this motion, and the more 

 readily also will it be forced through a defile 

 like Trelaporle. 



223. But in winter the thaw ceases ; the 

 quantity of water reaching the bed of the 

 glacier is diminished or entirely cut off. The 

 ice also, to a certain depth at least, is frozen 

 hard. These considerations would justify 

 the opinion that in winter the glacier, if it 

 moves at all, must move more slowly than in 

 summer. At all events, the summer meas- 

 urements give no clue to the winter motion. 



221. This point merits examination. I will 

 not, however, ask you to visit the Alps in 

 midwinter ; but, if you allow me, I will be 

 your deputy to the mountains, and report to 

 you faithfully the aspect of the region and 

 the behavior of the ice. 



32. WINTER ON THE MER DE GLACB. 



225. The winter chosen is an inclement 

 one. There is snow in London, snow ia 

 Paris, snow in Geneva ; snow near Champuni 

 so deep that the road fences are entirely 

 effaced. On Christmas night nearly at mid- 

 night 1859, your deputy reaches Chamouni. 



226. The snow fell heavily on December 

 20th ; but on the 2?th, during a lull in the 

 storm, we turn out. There are with me four 

 good guides and a porter. They tie planks 

 to their feet to prevent them from sinking iu 

 the snow ; I neglect this precaution and sink 

 often to the waist. Four or five times during 

 our ascent the slope cracks with an explosive 

 sound, aud the snow threatens to come down 

 in avalanches. 



The freshly-fallen snow \ /as in that partic- 

 ular condition which causes its granules to 

 adhere, and hence every flake fulling on the 

 trees had been retained there. The laden 

 pines presented beautiful and often fantastic 

 forms. 



227. After five hours and a half of arduous 

 work the Montanvert was attained. We un- 

 locked the forsaken auberge. round which 

 the snow was reared in buttresses. I have 

 already spoken of the complex play of crys- 

 tallizing forces. The frost-figures on thu 

 window-panes of the auberge were wonder- 

 ful : mimic shrubs and ferns wrought by the 

 building power while hampered by the ad- 

 hesion between the glass and the film in 

 which it worked. The appearance of the 

 glacier was very impressive ; all sounds were 

 stilled. The cascades which in summer fill 

 the air with their music were silent, hanging 

 from the ledges of the rocks in fluted col- 

 umns of ice. The surface of the glacier was 

 obviously higher than it had been in sum- 

 mer ; suggesting tho thought that while the 

 winter cold maintained the lower end of the 

 glacier jammed between its boundaries, the 

 upper portions still moved downward and 

 thickened the ice. The peak of the Aiguille 

 da Dru shook out a cloud banner, the origin 

 and nature of which have been already ex- 

 plained (84). 



228. On the morning of the 28th this ban- 

 ner was strikingly large and grand, and red- 

 dened by the light of tne rising sun it glowed 

 like a flame. Roses of cloud also clustered 

 round the crests of the Grande Jorasse and 

 hung upon the pinnacles of Charmoz. Four 

 men, well roped together, descended to the 

 glacier. I had trained one of them in 1857, 

 and he was now to fix the stakes. The 

 storm had so distributed the snow as to leave 

 alternate longths of the glacier bare anil 

 thickly covered. Whore much snow lay, 

 great caution was required, for hidden cre- 

 vasses were underneath. The men sounded 

 with their staffs at every step. Once while 

 looking at the party through my telescope 

 the leader suddenly disappeared ; the roof 

 of a crevasse had given way beneath him : 

 but the other three men promptly gathered 

 round and lifted him out of the fissure. The 

 true line was soon picked up by the thoodo 



