Rapid processes created them and are now destroying them.Humans have been living in the area now known as Utah for at least 12,000 years. Their loss is a sober reminder of how delicate-and recent-these formations are. Forty-three arches have collapsed due to erosion since 1970. Later, the sand and soil was removed, exposing the arches.Įventually arches will wear through and collapse. Acidic water in the sand and soil wore away these holes while the fins were still underground. Fragments began to loosen and fall, enlarging the openings into holes and then arches.Īlternately, some of the holes may have appeared at the bottoms of the fins in places where the fins had filled in with sand and soil. All this extra water caused the bases to weather more rapidly than the tops. The seeping water collected at the bases of the walls and evaporated slowly. Frost and cycles of freezing and thawing caused expansion and contraction of the rock surfaces, which progressively peeled off (exfoliated).Įventually holes appeared along the fractures that ran up and down the walls. Such weathering and erosion by water and wind enlarged the fractures to produce narrow parallel sandstone walls or fins. Slightly acidic rainwater slowly broke down the sandstone’s cement (made of lime), progressively releasing the sand grains. Most arches are carved out of the Entrada Sandstone, especially at the edges of the gentle hills that rose above the valleys. The uplift further released pressure on the sandstone and caused gentle warping in the Entrada Sandstone, opening up additional closely spaced, parallel joints, 10–20 feet (3–6 m) apart. Next this whole region was uplifted at the end of the Flood, and the waters that rushed violently off the continent washed away most of the layers above the sandstone. Other famous arches and bridges include Rainbow Bridge near Page, Arizona Shipton’s Arch in China (the tallest, at 1,200 feet) and Aloba Arch in Chad (the second tallest arch, at 394 feet). Later the Flood deposited another mile of younger sediments (about 5,000 feet, 1,524 m) on top of the Entrada Sandstone. The arching and bending of the sand layers over the salt domes produced parallel fractures in the sandstone. The weight of these accumulating rock layers caused the salt beds to liquefy and push up into salt domes. These sediment layers included the Navajo Sandstone and the Entrada Sandstone. During the Flood, hot salty waters deposited these beds in a wide basin in this area, now part of the Colorado Plateau region.Īfter the Flood deposited the salt beds, the waters tore debris from the nearby Uncompahgre Plateau (an Indian word meaning “dirty water” or “rocks that make water red”) and deposited the sands on top of the salt beds. Arches National Park sits atop thick underground salt beds, which are very unstable. Sandstone must be deposited on top of less stable material, which then shifts upward and causes the sandstone to break up into parallel strips. Today we’re looking at the remains of these rows of walls (fins).Ĭreating rows of rock walls requires special conditions. In most cases the whole wall would crumble, but in some cases only the lower portions collapsed. Only later did water, chemicals, and-to a lesser extent-wind eat away at these walls. They appear in parallel rows, like the furrows of a plowed field, and we can still see some today. These rock walls are called fins (see figure). First, some process had to create tall, thin rock walls, out of which the arches were carved. A long series of events had to happen beforehand. The problem is that they have chosen to ignore the unique impact Noah’s Flood had upon the earth’s surface.Ĭreating such delicate features requires more than gouging big holes into sandstone. The flood set in motion a sequence of events that produced such wonders very rapidly.Įvolutionary geologists recognize that massive earth movements were required, but they mistakenly assume long spans of time. Standing alone on a hillside is the world’s best-known arch, Delicate Arch, towering 85 feet (26 m) overhead.
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