Arches National Park - Natural Features & Ecosystems (U.S. National Park Service)

NPS Photo by Tom Gray

Sand Dune Arch, one of the thousands of catalogued arches

To many, the most outstanding natural features of Arches are the park's geologic formations. Over 2,000 catalogued arches range in size from a three-foot opening (the minimum considered to be an arch), to Landscape Arch which measures 306 feet from base to base. Towering spires, fins and balanced rocks complement the arches, creating a remarkable assortment of landforms in a relatively small area.

Two unusual natural features common in Arches intrigue both scientists and visitors: biological soil crust and potholes. Biological soil crust is a living groundcover that forms the foundation of high desert plant life.

Potholes are naturally occurring basins or pools in sandstone that collect rainwater and wind-blown sediment. These potholes harbor organisms that are able to survive long periods of dehydration, and also serve as a breeding ground for many desert amphibians and insects. Both of these communities are very vulnerable to human impacts.