One of the bedrooms at Camp Muir.
Even now, diminished as they are, the glaciers are fast transporting the Mountain toward the sea. Wherever a glacier skirts a cliff, it is cutting into its side, as it cuts into its own bed below. From the overhanging rocks, too, debris falls as a result of "weathering." The daily ebb and flow of frost and heat help greatly to tear down the cliffs. Thus marginal moraines built of the debris begin to form, on the ice, far up the side of the peak. As the glacier advances, driven by its weight and the resistless mass of snow above, it is often joined by another glacier, bringing its own marginal moraines. Where the two meet, a medial moraine results. (See illustrations, pp. [68] and [77].) Some medial moraines are many feet high. Trees are found growing on them. In Switzerland houses are built upon them. Often the debris which they transport, as the ice carries them forward, includes rocks as big as a ship.
A perilous position on the edge of a great crevasse. Cowlitz Glacier, near end of Cathedral Rocks.
A glacier's flow varies from a hundred to a thousand feet or more a year, depending upon its volume, its width, and the slope of its bed. As the decades pass, its level is greatly lowered by the melting of the ice. More and more, earth and rocks accumulate upon the surface, as it travels onward, and are scattered over it by the rains and melting snow. At last, in its old age, when far down its canyon, the glacier is completely hidden, save where crevasses reveal the ice. Only at its snout, where it breaks off, as a rule, in a high wall of ice, do we realize how huge a volume and weight it must have, far above toward its sources, or why so many of the crevasses on the upper ice fields seem almost bottomless.
