although the glaciers had little to do with the making of the Yosemite Valley, yet they added to its attractiveness. The valley is situated where a number of smaller streams join the Merced River. Erosion was more rapid here because the granite was soft, while the vertical seams in the rock gave the growing valley precipitous walls. When the glacier came it pushed out the loose rocks and boulders, and dropping a portion of them at the lower end, made a dam across the Merced River. At first a shallow lake filled the valley, but after a time the silt and gravel which the streams were continually bringing in filled the lake, and formed marshy flats. Finally, grasses and trees spread over these flats and gave the valley the appearance which it has to-day.
Besides the meadows, the glaciers gave us two of the waterfalls. Yosemite Creek, which comes down over the walls twenty-seven hundred feet in three successive falls, was turned into its present channel by a dam which a glacier had left across its old course. A glacier also turned the Merced River at its entrance to the main valley so as to form the Nevada Fall.
FIG. 15.—THE CAÑON OF BUBB'S CREEK, A BRANCH OF THE KING'S RIVER CAÑON
After the valley had been made and clothed in vegetation, it was discovered by a small tribe of Indians who came here to make their home, secure from all their enemies. There were fish in the streams and animals in the woods. The oaks supplied acorns, and in early summer the meadows were covered with strawberries. Legends were associated with many of the cliffs and waterfalls, for the Indians, like ourselves, are impressed by the wonders of Nature.
Hetch-Hetchy Valley, twenty-five miles north of the Yosemite, has been formed upon much the same plan, but a portion of its floor is marshy and there are few waterfalls. King's River Cañon has no green meadows and no high waterfalls, while its great granite walls are not so precipitous as those of the Yosemite. Next to the Yosemite, in the wildness of its scenery, is Tehipite Cañon. This cañon is situated upon the middle fork of King's River, about a hundred miles south. For many miles its walls and domes present ever changing views.
A continual struggle is going on between the forces within the earth and the sculptor working upon its surface. First one, then the other, gains the advantage. Where the mountains are steep and high, often the forces within have recently been active. Where they are low and the slopes are gentle, the sculptor has long held sway. She begins by making the surface as rough and picturesque as possible, but after a time she destroys her own handiwork.
[AN OREGON GLACIER]
There are records all about us of events which took place upon the earth long before there were any human inhabitants. These records have been preserved in the rocks, in the geographic features of the land and water, and in the distribution of the animals and plants. On every hand appear evidences of changes in the surface of the earth and in the climate.
Through all the central and northern United States, if we except some of the mountains of the West, the winter snows entirely disappear long before the coming of summer. But the climate of this region has not always been so pleasant and mild. Lands now densely peopled were once buried under a thick mantle of ice which lasted through many thousands of years.