Guided by one's ordinary sense or judgment alone, one's judgment as developed and disciplined by the everyday affairs of life and the everyday course of nature, one would say on beholding Yosemite that here is the work of exceptional and extraordinary agents or world-building forces. It is as surprising and exceptional as would be a cathedral in a village street, or a gigantic sequoia in a grove of our balsam firs. The approach to it up the Merced River does not prepare one for any such astonishing spectacle as awaits one. The rushing, foaming water amid the tumbled confusion of huge granite rocks and the open V-shaped valley, are nothing very remarkable or unusual. Then suddenly you are on the threshold of this hall of the elder gods. Demons and furies might lurk in the valley below, but here is the abode of the serene, beneficent Olympian deities. All is so calm, so hushed, so friendly, yet so towering, so stupendous, so unspeakably beautiful. You are in a mansion carved out of the granite foundations of the earth, with walls two or three thousand feet high, hung here and there with snow-white waterfalls, and supporting the blue sky on domes and pinnacles still higher. Oh, the calmness and majesty of the scene! the evidence of such tremendous activity of some force, some agent, and now so tranquil, so sheltering, so beneficent! That there should be two or three Yosemites in the Sierra not very far apart, all with the main features singularly alike, is very significant--as if this kind of valley was latent in the granite of that region--some peculiarity of rock structure that lends itself readily to these formations. The Sierra lies beyond the southern limit of the great continental ice-sheet of late Tertiary times, but it nursed and reared many local glaciers, and to the eroding power of these its Yosemites are partly due. But water was at work here long before the ice--eating down into the granite and laying open the mountain for the ice to begin its work. Ice may come, and ice may go, says the river, but I go on forever. Water tends to make a V-shaped valley, ice a U-shaped one, though in the Hawaiian Islands, where water erosion alone has taken place, the prevailing form of the valleys is that of the U-shaped. Yosemite approximates to this shape, and ice has certainly played a part in its formation. But the glacier seems to have stopped at the outlet of the great valley; it did not travel beyond the gigantic hall it had helped to excavate. The valley of the Merced from the mouth of Yosemite downward is an open valley strewn with huge angular granite rocks and shows no signs of glaciation whatever. The reason of this abruptness is quite beyond my ken. It is to me a plausible theory that when the granite that forms the Sierra was lifted or squeezed up by the shrinking of the earth, large fissures and crevasses may have occurred, and that Yosemite and kindred valleys may be the result of the action of