[154]
Sir Charles Lyell adds that, after what he saw on Mount Etna, he should
not be surprised to find layers of glacier and lava alternating in some
parts of Iceland.
Something similar was observed by Von Kotzebue, near the sound which
bears his name.[155] His party was encamped on a large plain covered
with moss and grass, when they discovered a fissure which revealed the
fact that the moss and grass were but a thin coating on a layer of ice a
hundred feet thick. This was not mere frozen ground, but aboriginal ice;
for, in the ice which formed the walls of the fissure, they found the
bones and teeth of mammoths embedded.
The frozen soil of Jakutsk, in Siberia, has for many years attracted
considerable attention. The ordinary law of increase of temperature in
descending below the surface of the earth would appear, however, to be
only modified here; for it is found in sinking a well which has
afforded opportunities for observing the state of the soil, that the
temperature gradually increases with the depth.[156]
Two ice-caverns were examined by Georgi, in the course of his travels in
Russia.
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