From the guidebook on page 673, "The flat face of HALF DOME (8,927 alt.) towers straight ahead nearly a mile above the valley floor."
Taken from Wikipedia, "Half Dome is a granite dome at the eastern end of Yosemite Valley in Yosemite National Park, California. It is a well-known rock formation in the park, named for its distinct shape. One side is a sheer face while the other three sides are smooth and round, making it appear like a dome cut in half. The granite crest rises more than 4,737 ft (1,444 m) above the valley floor"
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