annually to the
accumulation of snow in the higher regions,--not taking into account, of
course, the heavy drifts heaped up in particular localities, but
estimating the uniform average increase over wide fields. This snow is
gradually transformed into more or less compact ice, passing through an
intermediate condition analogous to the slosh of our roads, and in that
condition chiefly occupies the upper part of the extensive troughs into
which these masses descend from the loftier heights. This region is
called the region of the _neve_. It is properly the birthplace of the
glaciers, for it is here that the transformation of the snow into ice
begins. The _neve_ ice, though varying in the degree of its compactness
and solidity, is always very porous and whitish in color, resembling
somewhat frozen slosh, while lower down in the region of the glacier
proper the ice is close, solid, transparent, and of a bluish tint.

But besides the differences in solidity and in external appearance,
there are also many other important changes taking place in the ice of
these different regions, to which we shall return presently. Such
modifications arise chiefly from the pressure to which it is subjected
in its downward progress, and to the alterations, in consequence of this
displacement, in the relative position of the snow- and ice-beds, as
well as to the influence exerted by the form of the valleys themselves,
not only upon the external aspect of the glaciers, but upon their
internal structure also. The surface of a glacier varies greatly in
character in these different regions. The uniform even surfaces of the
upper snow-fields gradually pass into a more undulating outline, the
pure white fields become strewn with dust and sand in the lower levels,
while broken bits of stone and larger fragments of rock collect upon
them, which assume a regular arrangement, and produce a variety of
features most startling and incomprehensible at first sight, but more
easily understood when studied in connection with the whole series of
glacial phenomena. They are then seen to be the consequence of the
general movement of the glacier, and of certain effects which the course
of the seasons, the action of the sun, the rain, the reflected heat from
the sides of the valley, or the disintegration of its rocky walls, may
produce upon the surface of the ice. In the next article we shall
consider in detail all these phenomena, and trace them in their natural
co