Ascent of the Jungfrau in 1841. 313 
time before, for the marks they had left by rolling on the sur- 
face of the snow were still quite fresh. This was the only 
avalanche we met with during our expedition; and its con- 
fused appearance, which made it easily recognizable at a great 
distance, contrasted in a striking manner with the uniformity 
of the declivities of the snow-terraces, which, whatever a ce- 
lebrated geologist may allege, are here in no degree made 
smooth by the avalanches, although their inclination exceeds 
40 and 50 degrees, as we assured ourselves by repeated mea- 
surements.” We saw with interest that the fragments of this 
avalanche, detached from a peak of upwards of 11,000 feet in 
height, were composed of alternate beds of compact ice and 
congealed snow. These various layers, from two or three 
inches to a foot in thickness, alternated three or four times 
in blocks of a few cubic feet. This fact interested us the more 
warmly, because we saw in it the confirmation of an opinion 
expressed by M. Agassiz, and previously by M. Zumstein, on 
the mode in which bands of ice are formed in the midst of 
snow, even on the highest mountain summits, when the at- 
mospherie and topographical conditions of the place are fa- 
vourable. ¢ 
Our ladder was 23 feet long ; it was consequently more than 
sufficient to stretch across the great fissure. But immediately 
above the latter, the steepness of the terrace was fearfully great 
for a space of about 30 feet. We estimated it at 50°;- and, 
moreover, the snow, which had hitherto been very incoherent 
and almost powdery, had suddenly become of extreme density, 
to such a degree that the guides were obliged to cut steps. 
Our courage was here put to the first proof. Jacob and Jaun 
were the first to mount. When they were half way up the 
terrace, they let down the rope to us, holding it by one of the 
ends, and the other being fixed to the ladder, it served us as 
a kind of stair. All of us in this way arrived at the sum- 
‘mit of the terrace without mishap, but not without some 
ES Ace ec ee tA ib mes, Seal 
* M. Elie de Beaumont asserts, that “ all the slopes of snow with an in- 
clination approaching 30°, are smoothed down by avalanches, which renders 
them as rectilinear as the angles and cones produced by eruption.” — Mémoires 
pour servir ad une description géologique de la France, t. iy. p. 216. 
t See my note at the end of this article, ; 
