Note: The mass of compacted snow forming the upper part of a
glacier is called the firn, or n['e]v['e]; the glacier
proper consist of solid ice, deeply crevassed where
broken up by irregularities in the slope or direction
of its path. A glacier usually carries with it
accumulations of stones and dirt called moraines, which
are designated, according to their position, as
lateral, medial, or terminal (see {Moraine}). The
common rate of flow of the Alpine glaciers is from ten
to twenty inches per day in summer, and about half that
in winter.
{Glacier theory} (Geol.), the theory that large parts of the
frigid and temperate zones were covered with ice during
the glacial, or ice, period, and that, by the agency of
this ice, the loose materials on the earth's surface,
called drift or diluvium, were transported and
accumulated.