So inclosed, the bubbles of air are subject to the
same compression as the ice itself, and become more flattened in
proportion as the snow has been more fully transformed into compact ice.
As long as the transformation of snow into ice is not complete, a rise
of its temperature to 32 deg. Fahrenheit, accompanied with thawing, reduces
it at once again to the condition of loose grains of _neve_; but when
more compact, it always presents the aspect of a mass composed of
angular fragments, wedged and dove-tailed together, and separated by
capillary fissures, the flattened air-bubbles trending in the same
direction in each fragment, but varying in their trend from one fragment
to another. There is, moreover, this important point to notice,--that,
the older the _neve_, the larger are its composing granules; and where
_neve_ passes into porous ice, small angular fragments are mixed with
rounded _neve_-granules, the angular fragments appearing larger and more
numerous, and the _neve_-granules fewer, in proportion as the _neve_-ice
has undergone most completely its transformation into compact
glacier-ice. These facts show conclusively that the dimensions and form
of the _neve_-granules, the size and shape of the angular fragments, the
porosity of the ice, the arrangement of its capillary fissures, and the
distribution and compression of the air-bubbles it contains, are all
connected features, mutually dependent.
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