ges its character. From the light airy flake, it becomes, in
masses, what the geologists term _neve_. This is a granular
snow, intermediate between snow and ice. A little lower down this
_neve_ is converted into true glacial ice-beds, which grow
longer, broader, deeper and thicker as the _neve_ presses down
from above.

Lay minds conceive of these great ice-beds of transformed snow as
inert, immovable bodies. They think the snow lies upon the surface of
the rocks or earth. The scientific observer knows better. By the very
inertia of its own vast and almost inconceivable weight the glacier is
compelled to move. Imagine the millions of millions of tons of ice of
these sloping masses, pressing down upon the hundreds of thousands of
tons of ice that lie below. Slowly the mass begins to move. But
all parts of it do not move with equal velocity. The center travels
quicker than the margins, and the velocity of the surface is greater
than that of the bottom. Naturally the velocity increases with the
slope, and when the ice begins to soften in the summer time its rate
of motion is increased.

But not only does the ice move. There have been other forces set in
motion as well as that of the ice. The fierce attacks of the storms,
the insidious forces of frost, of expansion and contraction, of
lightning, etc., have shattered and loosened vast masses of the
mountain summits. Some of these have weathered into toppling masses,
which required only a heavy wind or slight contractions to send them
from their uncertain bases onto the snow or ice beneath. And the other
causes mentioned all had their influences in breaking up the peaks
and ridges and depositing great jagged bowlders of rock in the
slowly-moving glaciers.

Little by little these masses of rock worked their way down lower into
the ice-bed. Sometime they must reach the bottom, yet, though
they rest upon granite, and granite would cleave to granite, the
irresistible pressure from above forces the ice and rock masses
forward. Thus the sharp-edged blocks of granite become the
_blades_ in the tools that are to help cut out the contours of
a world's surface. In other words the mass of glacial ice is the
grooving or smoothing _plane_, and the granite blocks, aided
by the ice, become the many and diverse blades in this vast and
irresistible tool. Some cut deep and square, others with flutings and
bevelings, or curves, but each helps in the great work of planing off,
in some way,