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Arches National Park (17)
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![Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 1835 W: 109 N: 4233]](http://i1.treknature.com/misc/g-g-g.gif) (14036) | Park avenue is one of the first scenes you gaze upon after entering Arches National Park. I have to say, its one of the most amazing places I’ve ever been to.
Water and ice, extreme temperatures and underground salt movement are responsible for the sculptured rock scenery of Arches National Park. On clear days with blue skies, it is hard to imagine such violent forces, or the 100 million years of erosion that created this land that boasts the greatest density of natural arches in the world. The more than 2,000 catalogued arches range in size from a three-foot opening, the minimum considered an arch, to the longest one, Landscape Arch, which measures 306 feet from base to base. New arches are being formed and old ones are being destroyed. Erosion and weathering are relatively slow but are relentlessly creating dynamic landforms that gradually change through time. Occasionally change occurs more dramatically. In 1991 a slab of rock about 60 feet long, 11 feet wide and 4 feet thick fell from the underside of Landscape Arch, leaving behind an even thinner ribbon of rock. Delicate Arch, an isolated remnant of a bygone fin, stands on the brink of a canyon, with the dramatic La Sal Mountains for a backdrop. Towering spires, pinnacles and balanced rocks perched atop seemingly inadequate bases vie with the arches as scenic spectacles.
The park lies atop an underground salt bed, which is basically responsible for the arches and spires, balanced rocks, sandstone fins and eroded monoliths that make the area a sightseer's mecca. Thousands of feet thick in places, this salt bed was deposited across the Colorado Plateau some 300 million years ago when a sea flowed in the region and eventually evaporated. Over millions of years, the salt bed was covered with residue from floods and winds and the oceans that came and went at intervals. Much of this debris was compressed into rock. At one time this overlying layer of rock may have been more than a mile thick.
Faults deep in the Earth contributed to the instability on the surface. The result of one such 2,500-foot displacement, the Moab Fault, is seen from the visitor center. Winds later cleared out the loose particles. A series of free-standing fins remained. Wind and water attacked these fins until, in some, the cementing material gave way and chunks of rock tumbled out. Many damaged fins collapsed. Others, with the right degree of hardness and balance, survived despite their missing sections. These became the famous arches. Pothole arches form by chemical weathering as water collects in natural depressions and eventually cuts through to the layer below. This is the geologic story of Arches.
Another view of the same location is in the worksh
Source: Arches National Park web site |
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