Many of the great valleys of the far north are completely filled up with solid ice. Observe, we do not say that they are merely covered over with ice; they are absolutely filled up with it from top to bottom. Those ice-masses are known by the name of glaciers; and they are found in most of the elevated regions of the Earth,--on the Alps and the mountains of Norway, for instance,--but they exist in greater abundance about the poles than elsewhere. Glaciers _never_ melt. They have existed for unknown ages, probably since the world began; and they will, in all likelihood, continue to exist until the world comes to an end,--at least until the present economy of the world terminates. They began with the first fall of snow, and as falls of snow during the long winters of the polar regions are frequent and heavy, the accumulated masses are many feet deep, especially in places where drifts are gathered--sometimes fifteen, twenty, thirty, and even forty feet deep. The summer sun could not melt such drifts entirely. New snow was added each winter, until the valleys of the far north were filled up; and so they remain filled up to this day. In order to understand the nature of glaciers clearly, let us turn back to those remote ages that rolled over this Earth long before man was created. Let us in spirit leap back to the time when no living creature existed, even before the great mastodon began to leave his huge foot-prints on the sands of time. We have reached one of the large valleys of the arctic regions. It is solemn, grand, and still. No merry birds, no prowling creatures, are there to disturb the universal calm. The Creator has not yet formed the living creatures and pronounced them "very good." It is the world's first winter. As we look upward to the sky, we observe the first white snow-flakes falling gently to the ground. They reach it, and, for the first time, that valley is covered with a garment of virgin snow. The valley is upwards of two miles broad. It rises from the sea, and goes far back into the mountains, perhaps to the extent of ten or twelve miles. The mountains that flank it are five or six thousand feet high. We have seen such valleys in Norway, within the arctic circle. Before that first winter has passed, many and many a fall of snow has thickened and pressed down that first coat; and many a furious storm has caught up the snow from the mountain-tops and swept it into the valley, adding to and piling up the mass, and packing it firmly down.