148 Professor Forbes's Thirteenth Letter on Glaciers. 



on the higher part of tlie Glacier du Geant, where the still 

 snowy ice, marked with the horizontal annual strata, is shoved 

 violently down the steep, which occasions the scene of de- 

 solate confusion between the Aiguille Noire and the rock 

 called Le Petit Rognon. The structure of the interior of the 

 embryo glacier is here perfectly disclosed by the prodigious 

 vertical rents which make the scene a true giant's staircase ; 

 the ice-falls succeeding one another at regulated intervals, 

 which appear to correspond to the renewal of each summer's 

 activity in these realms of almost perpetual frost, when a 

 swifter motion occasions a more rapid and wholesale projec- 

 tion of the mass over the steep, thus forming curvilinear 

 terraces like vast stairs, which appear afterwards, by conso- 

 lidation, to form the remarkable protuberant wrinkles on the 

 surface of the Glacier du Geant described in my Fifth Let- 

 ter.* But the point which at present concerns us is this, 

 that, according to the best observations which I could make, 

 the stratified appearance of the Neve disappeared at a depth 

 inconsiderable compared to the vast vertical sections there 

 exposed, and the interior of the mass was granular, and with- 

 out structure or hands of any kind. 



I drew the very same conclusion from an attentive survey 

 of the Glacier de Talefre, w^iich is peculiarly calculated to 

 throw light upon this question, and I shall state the result 

 of my observations there nearly in the words in which I re- 

 corded them immediately after they were made. A little 

 higher up than the usual passage of the glacier to the Jardin, 

 or near the upper limit of the sketch, Plate II., fig. 2, the 



•^ It is not unimportant for travellers to be aware that in seasons like 1840, 

 of unusual warmth and activity amongst the glaciers, the dislocation and pre- 

 cipitous subsidence of the tabular masses of the Neve is occasionally so complete 

 as absolutely to debar a passage, at least without the help of a ladder. This 

 was the case when I ascended the Glacier du Geant on the 14th August last, a 

 snow bridge by which some travellers had effected a passage a fortnight before 

 having wasted away. Had travollei's at that time crossed the Col du Geant 

 from Courmayeur to Chamouni, they might have found their descent, if not 

 impracticable, at least most perilous, and to return from such a distance would 

 have been an almost equally distressing alternative. On this account it is most 

 advisable to make this passage from the side of Cliamouui. 



