Established: November 12, 1971
Size: 76,359 acres
This park contains more than 2,000 natural arches—the greatest concentration in the country. But numbers have no significance beside the grandeur of the landscape—the arches, the giant balanced rocks, spires, pinnacles, and slickrock domes against the enormous sky.
Perched high above the Colorado River, the park is part of southern Utah's extended canyon country, carved and shaped by eons of weathering and erosion. Some 300 million years ago, inland seas covered the large basin that formed this region. The seas refilled and evaporated—29 times in all—leaving behind salt beds thousands of feet thick. Later, sand and boulders carried down by streams from the uplands eventually buried the salt beds beneath thick layers of stone. Because the salt layer is less dense than the overlying blanket of rock, it rises up through it, forming it into domes and ridges, with valleys in between.
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