Half Dome Yosemite National Park.
20th c American Topographical View
Hubert A. MCCLAIN
(Protection. Kansas, 1909 - 1994, Long Beach. California)
Yosemite National Park. California. U.S.A.
Half Dome sits quietly above the famous Yosemite Valley. It is an excellent example of a granite expoliation dome. The granite magna had intruded into overlying rock creating the dome. As techtonic forces caused the Sierra Nevada slowly to rise, rivers cut into the rising mass removing the overlying rocks, exposing the granite and cutting spectacular deep valleys. As erosion removed the overlying rocks the release of pressure on the granite caused nested convex upward fractures to form. These factures are known as expoliation fractures. They can be seen here above the lip of Half Dome justt to the right of the black streak rising to the lip.
The spectacular cliff face of Half Dome was caused by the river in Tanaya Canyon cutting against the dome, causing slabs of rock to break away along vertical fractures that ran through the dome.
MCCLAIN Hubert A. | Half Dome Yosemite National Park. | | American |
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