Mr, J. Ball on the Structure of Glaciers. 499 
to form a nearly continuous mass, some. degree of discontinuity 
must occasionally remain. 
The cleavage of the veined structure is accounted for by the 
effect of great pressure transverse to the already existing surfaces, 
probably accompanied by the partial flattening of the air-bubbles 
im a portion of the mass. 
So far, I venture to think that the stratification theory, though 
not free from difficulties of its own, may well compare with its 
rivals. There is, however, a class of glaciers which differ widely 
from all others in the mode of their formation, and whose strue- 
ture has been regarded as incompatible with that theory. I 
allude to the “glaciers remaniés”’ which are formed at the base 
of lofty precipices when the latter are surmounted by steep 
slopes of snow or ice, which from time to time descend in dust= 
like showers, forming avalanches, such as are watched by tourists. 
from their habitual haunts on the Wengern Alp and the Great 
Scheideck. Below the latter pass, in a hollow at the very base 
of the precipitous face of the Wetterhorn, is a glacier of this 
class, called the Lower Glacier of Schwarzwald, which has already 
attracted the attention of M. Desor and of M. Charles Martins. 
Being sufficiently easy of access, this glacier offers one of the 
most favourable opportunities for studying the structure of such 
glaciers, and I thought myself fortunate in being able to visit it 
on the 13th of August last. The form of the glacier is that of 
a segment of a cone, whose apex, abutting against the rocks, is 
formed by the snow or fragments of ice that descend about 4000 
feet from a steep slope below the peak of the Wetterhorn. The 
glacier preserves on all sides a tolerably regular slope of about 
30° with the horizon*, but where it abuts upon the nearly level 
bottom of the valley, the front is in some places cut away into. 
steep faces from 20 to 40 feet in height. On examining this part 
of the glacier, it was found to be formed for the most part of a 
uniform mass of white ice, everywhere filled with air-bubbles, 
and without any appearance-of veined structure. The bubbles 
showed very slight and occasional traces of compression in any 
direction, in this respect differing from all ordinary glacier ice. 
Nevertheless, when masses of the ice were forcibly struck with a 
heavy iron-pointed stick, it became evident that there was a 
distinct tendency to cleavage in parallel planes. On further exami- 
nation the veined structure was found here and there imperfectly 
developed, and in a few instances single bands of blue ice, 1 or 2 
inches thick and several feet in length, perfectly clear and without 
air-bubbles, were seen in positions conformable to the direction 
of the cleavage planes. Along the steep terminal slopes nearly 
* This measure is given from recollection, my notes being defective on 
this point. 
2K2 
