In trying to penetrate farther along the face, I
found a wing of the brown fly we had seen in considerable abundance on
the ice in La Genolliere, frozen into the remains of a column.
There was so very much to be observed on all sides, and the measurements
took up so much time, owing to the peculiar difficulties which attended
them, that I did not examine with sufficient care the curious floor of
ice through which we cut our way to the lower cavern. Neither did I
notice the roof of the cavern thus reached, which may be very different
from the shape of the upper surface of the floor composing it. If the
ice-wall goes straight up, and the roof is formed of the ice-floor
alone, then it is a very remarkable feature indeed. But, more probably,
the lower wall leans over more and more towards the top, and so forms as
it were a part of the roof. It is possible that, as the wall has grown,
each successive annual layer has projected farther and farther, till at
last some year very favourable to the increase of ice has carried the
projection for that year nearly to the opposite stones, and then an
unfavourable year or two would form the foot of the upper wall.
Pages:
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77