Professor Forbes's Twelfth Letter on Glaciers, 95 



very nearly, if not quite, to the level of that moraine, so as 

 to follow the natural curve of the soil, which it everywhere 

 touched, presenting a steep wall of nearly unbroken ice, 

 70 feet in height, facing the bank. Again, opposite to 

 the remarkable chapel of Notre Dame de la Guerison, of 

 which I have given an account in my Travels, with the his- 

 tory of its invasion and ruin by the progress of the ice in 

 1818, the ice has risen against the projecting rock, beneath 

 the old larch tree (seen in Plate IV. of my Travels, and in 

 Plate I., fig. 1, accompanying this paper), and seems to 

 threaten the security of the path, in the same manner as it 

 did at that time. " The height of this rock," I stated in 

 1842, " is now about 300 feet ;" in August 1846 it was 

 scarcely more than 100 ! and as the glacier towered up to a 

 great height beyond, it had all the appearance of menacing 

 the pathway, and once more tearing up the limestone rock. 

 But this will be still more distinctly conceived by referring to 

 Plate I., figures 1 and 2, which shew the size of the glacier 

 in 1846 contrasted with the view of 1842. Both these sketches 

 were taken from the same spot (marked A on the ground plan), 

 and as I had not,'on the latter occasion, my former drawing for 

 comparison, the evidence of the increase is the more striking, 

 and the accuracy of outline of the fixed parts of the land- 

 scape is confirmed. The increase of height and length of 

 the glacier, as well as its breadth, is here well marked. In 

 consequence of this great accumulation of ice (accompanied, 

 probably, by an increased velocity of motion), the surface 

 of the glacier is exceedingly crevassed, in some places even 

 divided into pinnacles, and, generally, incapable of being 

 traversed witliout great difficulty, although, in 1842, I could 

 have walked over it in almost every direction. 



The cause of this very surprising increase is a general 

 one, since most of the glaciers which have been recently ex- 

 amined, present it in a more or less striking degree ; for in- 

 stance, the Glaciers des Bois and Bossons, in the valley of 

 Chamouni.* The cause is no doubt to be sought partly in the 



* A very striking evidence of this change has occurred at Chamouni. The 

 torrent Arveiron, instead of issuing from beneath the bed of the Glacier des 



