  Little need be said of the Yosemite Valley. After these many years of visitation and exploration it remains incomparable. It is often said that The Yosemite Valley was discovered in 1851 as an incidental result of the effort to settle Indian problems which had arisen in that region. Dr. L. H. Bunnel, a member of the expedition, suggested the appropriateness of naming it after the aborigines who dwelt there. It rapidly became celebrated. An unusual view of Yosemite Valley from the Nevada Fall Trail. No matter what their expectation, most visitors are delightfully astonished upon entering the Yosemite Valley. The sheer immensity of the precipices on either side of the Valley’s peaceful floor; the loftiness and the romantic suggestion of the numerous waterfalls; the majesty of the granite walls; and the unreal, almost fairy quality of the ever-varying whole cannot be successfully foretold. The Valley is 7 miles long. Its floor averages 1 mile in width, its walls rising from 3,000 to 4,000 feet. HOW THE VALLEY WAS FORMEDAfter the visitor has recovered from his first shock of astonishment—for it is no less—at the beauty of the Valley, inevitably he wonders how nature made it. How did it happen that walls so enormous rise so nearly perpendicular from the level floor of the Valley? When the Sierra Nevada was formed by the gradual tipping of a great block of the earth’s crust 400 miles long and 80 miles wide, streams draining this block were pitched very definitely toward the west and with torrential force cut deep canyons. The period of tipping and stream erosion covered so many thousands of centuries that the Merced River was able to wear away the sedimentary rocks several thousand feet in thickness, which covered the granite and then in the Yosemite Valley region to cut some 2,000 feet into this very hard granite. Meantime the north and south flowing side streams of the Merced, such as Yosemite Creek, not benefited by the tipping of the Sierra block, could not cut as fast as their parent stream and so were left high up as hanging valleys. During the Ice Age great glaciers formed at the crest of the range and flowed down these streams, cutting deep canyons and especially widening them. At the maximum period the ice came within 700 feet of the top of Half Dome. It overrode Glacier Point and extended perhaps a mile below El Portal. Glaciers deepened Yosemite Valley 500 feet at the lower end and 1,500 feet opposite Glacier Point; then widened it 1,000 feet at the lower end and 3,600 feet in the upper half. The V-shaped canyon which had resulted from stream erosion was now changed to a U-shaped trough; the Yosemite Cataract was changed to Yosemite Fall. As the last glacier melted back from the Valley a lake was formed, the filling in of which by sediments has produced the practically level floor now found from El Capitan to Half Dome. Visitors to the park should join an auto caravan to study evidences first hand and hear the story of the geology of Yosemite discussed by the ranger-naturalists. WATERFALLSThe depth to which the Valley was cut by streams and glaciers is measured roughly by the extraordinary height of the waterfalls which pour over the rim. The Upper Yosemite Fall, for instance, drops 1,430 feet in one sheer fall, a height equal to nine Niagara Falls piled one on top of the other. The Lower Yosemite Fall, immediately below, has a drop of 320 feet, or two Niagaras more. Counting the series of cascades in between, the total drop from the crest of Yosemite Fall to the Valley floor is 2,565 feet. Vernal Fall The falls are at their fullest in May and June while the winter snows are melting. They are still running in July, but after that decrease rapidly in volume, Yosemite Fall often drying up entirely by August 15 when there has been little rain or snow. But let it not be supposed that the beauty of the falls depends upon the amount of water that pours over their brinks. It is true that the May rush of water over the Yosemite Fall is even a little appalling, when the ground sometimes trembles with it half a mile away, but it is equally true that the spectacle of the Yosemite Fall in late July, when, in specially dry seasons, much of the water reaches the bottom of the upper fall in the form of mist, possesses a filmy grandeur that is not comparable probably with any other sight in the world; the one inspires by sheer bulk and power, the other uplifts by its intangible spirit of beauty. To see the waterfalls at their best one should visit Yosemite before July 15. HEIGHT OF WATERFALLS
| ||||||||||||||||||||||||||||||||||||||||||||
|
