San Rafael Reef: A lesson in geology in central Utah

San Rafael Reef
 

The San Rafael Reef is a unique geologic feature that is bisected by Interstate 70 as it runs through central Utah. It is located at the eastern end of the 75-mile long and 45-mile wide San Rafael Swell.

The San Rafael Swell was created millions of years ago by enormous geologic upheavals that created a “swell” in the earth’s surface.

At the reef, these geologic actions forced mountains and gigantic boulders  to lie at an angle; these formations are made of Navaho and Wingate sandstone that have been shaped by erosion. The reef is located in high desert country about 30 miles west of Green River, Utah. There are numerous slot canyons in the reef area; a slot canyon is one that is deeper than it is wide.

The swell is considered a wilderness area, populated with antelope and wild horses, and crossed by roads that can only be driven in four-wheel drive vehicles. Much of the swell is administered by the Bureau of Land Management.