The Precambrian granite of the Bighorn Mountains is the oldest in the world.
The Bighorn Range is approximately 120 miles long and from 30 to 50 miles
wide. For the most part, it is glacially sculpted alpine terrain. Cloud Peak,
at the southern end of the range, rises to an elevation of 13,167 feet.
The fossils of primitive armored and jawless fish found in the Bighorns are
the oldest known vertebrate fossils in the world. They come from the Ordovician
epoch, some 440-500 million years ago.
The Bighorns were fiercely defended by the Crow for their hunting and spiritual
Medicine Wheel, at the northern end of the range, is one of
Wyoming's most famous archaeological sites. Made of limestone rocks,
the wheel is over 70 feet in diameter and has 28 spokes.
Medicine Wheel was discovered by white men in 1880. The Crow said it was made "by people who had no iron."
Medicine Wheel is a sacred site to numerous Native American tribes.
While it is still acessible to visitors, in 1993 the Forest Service
restricted vehicle access to the site.