San Rafael Swell was formed eons ago, when geologic changes created a massive dome-like shape (anticline) in the earth's surface. Sandstone, limestone, and shale were pushed up, only to be eroded over the centuries into numerous canyons, mesas, gorges, and buttes. Overall, the San Rafael Swell covers an area of over 2,000 square miles. Around 217,000 acres of this area is known as the San Rafael Recreation Area and is managed by the US Bureau of Land Management. The swell is divided by Interstate 70 into two sections. The northern section is drained by the San Rafael River; the southern section is drained by Muddy Creek. San Rafael Swell contains numerous unique areas to visit. Below, we've listed a few of the best ones.