Geologists estimate that it would have taken 70,000 years of water, frost and wind operating in a dry climate to form the isolated Delicate Arch in Arches National Park (figure 4). It is assumed that it takes a long time to form an arch. (4) continued weathering that enlarges the holes and eventually causes the arch to collapse. (3) continuing erosion with some fins breached from below and (2) weathering and erosion that enlarge fractures resulting in narrow walls or ‘fins’ (1) uplift that causes deep vertical, parallel fractures to form Rock arches are believed to form slowly over long periods of time by physical and chemical weathering. Rock arches can be on ridges or the sides of a ridge. Although an arch is similar to a natural bridge, it differs from a natural bridge because it does not span a valley formed by erosion. Most free standing rock arches are believed to have formed without stream erosion. Such windows could form rapidly by weathering of the soft strata. The small holes are called windows in Bryce Canyon National Park (figure 3). The large ones are high enough to contain the Capitol building in Washington D.C. They range from Landscape Arch in Arches National Park, the longest in the world, with a span of 88 m (290 ft) to small holes. The collapse of such arches provides evidence that long free standing arches and many tall natural bridges likely formed rapidly during the Flood. It was the 12 th largest arch of the estimated 2,000 arches in Arches National Park. The arch is located along the popular Devils Garden Trail and was more than 10 m (33 ft) tall and spanned 22 m (71 ft) across before collapse (figure 2). One of the most photographed free standing arches in Arches National Park, Wall Arch, in southeast Utah, USA, collapsed sometime late Monday or early Tuesday of August 4 th and 5 th, 2008 (figure 1). A rapid process of erosion in the past consistent with the Retreating Stage of the Flood is more likely. However, the uniformitarian hypotheses for their origin are not observed. The formation of large arches and natural bridges from slow weathering and erosion would take tens of thousand of years. Freestanding rock arches and large natural bridges are observed to collapse today, such as Wall Arch in Arches National Park in early August 2008.
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