Mesa Arch, Natural arch in Island in the Sky, United States.

Mesa Arch is a pothole arch on the eastern edge of the Island in the Sky mesa in Canyonlands National Park, Utah. A thick band of pale tan and grayish layered sandstone forms a flat-topped span; its underside is vivid orange-red, rough and uneven. Below, a shelf of blocky reddish-orange rock broken into cracked slabs and rounded ledges sits above a vast canyon.

The arch formed over millions of years through water erosion of Navajo Sandstone, gradually shaping the natural opening. This geological process is the same force that carved deep canyons and other rock formations throughout the region.

Mesa Arch also appears among the landscape wallpapers shipped with Windows 7, which introduced the formation to viewers far beyond Utah. The arch carries two other names, Rotary Arch and Trail Arch. Sunrise remains the hour when photographers line the rim of the cliff below the span.

The trail to Mesa Arch is a half-mile walk from the park road, and spring and fall are the most favorable seasons. The arch sits on the eastern edge of the Island in the Sky mesa, so the walk ends at a cliff edge above the canyon. The area is a cold semi-arid desert with less than 10 inches of rain a year and light winter snow.

Mesa Arch is also called Rotary Arch and Trail Arch. It appears as one of the desktop wallpapers in the Landscapes section of Windows 7, a detail many visitors do not know.