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Yosemite’s most distinctive monument, Half Dome, dominates most Valley views. Standing at the eastern end of Yosemite Valley, Half Dome rises to an elevation of 8,842 feet. At 87 million years old, the type of granite making up the dome is the youngest plutonic rock in the Valley. (Plutonic rock is formed beneath the earth’s surface by intense heat, pressure and slow cooling.) The remaining portions of granite on Half Dome’s face are believed to have sheered off during its cooling phase 100 million years ago, deep under the Pacific seabed. Succeeding glaciers deposited some of the debris in moraines along the Valley floor.