Slickrock Trail near Moab, Grand County, Utah
Photographer: Jim Davis
Giant weathering pits or potholes like this one (about 16 feet across at the bottom) in the Jurassic-age Navajo Sandstone typically form along fractures and joints atop fins, knolls, and rounded domes. Potholes are created through a combination of physical, chemical, and biological processes that weather and erode the rock and are home to a remarkable array of ancient aquatic organisms.