About Four O'clock
This Afternoon, When I Was Waiting For The Evening Shadows To Enable
Me To Get Nearer The
Main camp, where I could be more easily found in
case my eyes should become still more inflamed and I
Should be unable
to travel, thin clouds cast a grateful shade over all the glowing
landscape. I gladly took advantage of these kindly clouds to make an
effort to cross the few miles of the glacier that lay between me and
the shore of the inlet. I made a pair of goggles but am afraid to
wear them. Fortunately the ice here is but little broken, therefore
I pulled my cap well down and set off about five o'clock. I got on
pretty well and camped on the glacier in sight of the main camp,
which from here in a straight line is only five or six miles away. I
went ashore on Granite Island and gleaned a little fossil wood with
which I made tea on the ice.
July 20. I kept wet bandages on my eyes last night as long as I
could, and feel better this morning, but all the mountains still
seem to have double summits, giving a curiously unreal aspect to the
landscape. I packed everything on the sled and moved three miles
farther down the glacier, where I want to make measurements. Twice
to-day I was visited on the ice by a hummingbird, attracted by the
red lining of the bear-skin sleeping-bag.
I have gained some light on the formation of gravel-beds along
the inlet. The material is mostly sifted and sorted by successive
railings and washings along the margins of the glacier-tributaries,
where the supply is abundant beyond anything I ever saw elsewhere.
The lowering of the surface of a glacier when its walls are not too
steep leaves a part of the margin dead and buried and protected from
the wasting sunshine beneath the lateral moraines. Thus a marginal
valley is formed, clear ice on one side, or nearly so, buried ice
on the other. As melting goes on, the marginal trough, or valley,
grows deeper and wider, since both sides are being melted, the land
side slower. The dead, protected ice in melting first sheds off the
large boulders, as they are not able to lie on slopes where smaller
ones can. Then the next larger ones are rolled off, and pebbles
and sand in succession. Meanwhile this material is subjected to
torrent-action, as if it were cast into a trough. When floods come
it is carried forward and stratified, according to the force of the
current, sand, mud, or larger material. This exposes fresh surfaces
of ice and melting goes on again, until enough material has been
undermined to form a veil in front; then follows another washing and
carrying-away and depositing where the current is allowed to spread.
In melting, protected margin terraces are oftentimes formed. Perhaps
these terraces mark successive heights of the glacial surface.
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