Arches National Park, 76,519 acres (30,979 hectares), E Utah; est. as a national monument 1929, designated a national park 1971. Located in red-rock country and overlooking the gorge of the Colorado River, this area contains a vast and unusual array of natural rock formations. Water, frost, and wind have carved giant but graceful arches, windows, spires, and pinnacles. See National Parks and Monuments (table).