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The Yosemite Valley (1910) by Galen Clark

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THEORIES IN REGARD TO THE ORIGIN
OF YOSEMITE.


"HOW was this wonderful valley formed?" is a question asked by thousands of visitors, and there have been three distinct theories advanced by different geologists on this subject. Prof. J. A Whitney, in his report as State Geologist, says:

"The Valley is too wide to have been formed by a fissure. Much less can it be supposed that the peculiar form of Yosemite is due to the erosive action of ice. A more absurb theory was never advanced than that by which it was sought to ascribe to glaciers the sawing out of these vertical walls and the rounding of the domes. In short, we are led irresistibly to the adoption of a theory of the origin of Yosemite in a way which has hardly yet been recognized as one of those in which valleys may be formed, probably for the reason that there are so few cases in which such an event can be absolutely proved to have occurred.

"We consider that during the process of upheaval of the Sierra, or, possibly, at some time after that had taken place, there was at the Yosemite a subsidence of a limited area, marked by lines of ‘fault’ or fissures crossing each other somewhat nearly at right angles. In other and more simple language, the, bottom of the Valley sunk down to an unknown depth owing to the support being withdrawn from underneath during. some of those convulsive movements which must have attended the upheaval of so extended and elevated a chain, no matter how slow we may imagine the process to have been."

I have been informed that Prof. Silliman and some other noted geologists, who were among the early visitors to Yosemite, conceived and advanced the theory that the Valley was formed by a great subterranean force causing a deep rupture in the surface of the earth, which in an unknown period of time has been filled up to the present floor of the Valley.

The third theory, and perhaps the most popular one at the present time, is that the origin and general formation of the Valley is due to the agency of glaciers. Clarence King, who was one of Prof. J. D. Whitney’s topographical engineers in the survey of Yosemite Valley and the adjacent mountain range, was the first geologist to advance the opinion that Yosemite Valley was formed by glacial agency. In later years, Prof. Joseph Le Conte and other noted geologists, in their many visits to Yosemite and explorations in the High Sierras, and after examining the old glacial moraines, terminal, lateral and medial, still to be plainly seen on the floor of the Valley, also the stria and other evidence of glacial erosion in many places high up on the walls of the Valley, and the glacial polish still in evidence on the rocks above the falls of all the large streams entering the Valley, together with the extensive areas of polished granite higher up in the range, came to the positive conclusion that the Yosemite Valley was formed by the agency of glaciers instead of either a local subsidence or a rupture. of the earth’s surface.

[Editor’s note: this "third theory" was originated by John Muir, not Clarence King. King originally accepted Whitney’s theory, but later accepted Muir’s theory after Muir proposed it (see Badè’s The Life and Letters of John Muir, Ch. 9). —DEA]

North Dome, by George Fiske
NORTH DOME
3,725 feet
[Photo by George Fiske]


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