Location: Near Moab, UT, May 2008
I was at Arches National Park for a single day in May with John, Ken and Pam. Since one day is not nearly enough to see the park, I had planned to return to the area after I left Colorado -- but my broken ankle made that plan evaporate. One of the arches I didn't see then I won't ever see -- on August 4th, the first full day I would have been in the park, the 12th largest arch in the park came tumbling down.
Arches National Park is composed of sandstone formations that take a variety of shapes: large standing rocks, hoodoos, walls of rock, and the famous arches. What is now high desert country was, millions of years ago, a huge salty sea. The sea eventually evaporated, leaving enormous salt flats that were subsequently covered by sand. The sand compressed over time into layers and layers of sandstone. The underlying salt layer was very unstable, and began to flow under the weight of the sandstone, causing buckling, shifting, thrusting, and creating cavities and vertical cracks.
As time went on, wind, water, and ice eroded the softer rock leaving fins scattered throughout the landscape. As the softer rock continued to break off and erode, openings were created in the fins, and these openings continued to expand until they became the arches we know today.
Mother Nature has not finished with Arches National Park -- new arches continue to form, and old arches collapse into rubble. Throughout the park, solid fins can still be seen, and also fins with small holes in their middle -- fins that are on their way to being the arches our descendants will come to see. Existing arches continue to erode, and, as happened August 4th, the arch will collapse when its thinness and cracks make the rock too fragile to support its enormous weight. The park will continue to have arches for a long time to come -- but the landscape will never look the same for very long.