Gregory Natural Bridge is a natural sandstone bridge in the Glen Canyon National Recreation Area that was covered by Lake Powell filling up since Glen Canyon Dam’s completion in 1966. The 137-foot arch was last seen in 1969 but has recently resurfaced with declining lake levels.

Lake Powell hit its lowest water level in 2023 since being filled in 1980. The declining water levels have revealed other hidden treasures like Cathedral in the Desert.

The arch was formed by thousands of years of erosion. Erosion causes certain sections of the sandstone to become more vulnerable to weathering, while others remain relatively intact. As water seeps into cracks and freezes in cold climates, the rock expands and leads to the widening of gaps and fractures. Eventually, an arch-shaped opening is formed.