How were the stunning formations at Arches National Park created? That is a very long story. 300 million years ago, this area was underwater. As the sea evaporated, it left behind a salt bed measuring over a thousand feet deep named the Paradox Formation. Layers of debris piled on. 200 million years ago, the region (called the Colorado Plateau) became a desert and gathered more sediment similar to a layer cake. By the next 50 million years, the sedimentary rock reached a depth of 5,000 feet. All of this weight caused the underlying salt to liquefy, shift upwards and create domes while faulting the Entrada Sandstone. During subsequent millenniums, wind, rain and ice plus dramatic shifts in daily temperature chipped away at the exposed salt and weaker rock. The erosion resulted in tall, narrow walls of hard rock called fins. Two examples are The Organ (right) and the Tower of Babel (left). At times, these massive formations were softer in the middle. The forces of nature sculpted these fragile centers into the park’s famous arches.
