The San Andres Mountains in New Mexico are some of the most southern-most mountains of the Rocky Mountains. They’re extremely dry, with very few areas that can support woodlands. Much of the range is restricted as it is within the highly restricted White Sands Missile Range. Like many other ranges in the southwest, they were formed when block faults shifted upwards.  The San Andres Mountains are also protected as they are the habitat of up to 400 bighorn sheep. While searching for the Lost Padre Mine, Jeff Kinner discovered the Tuar Tums first Port Door in a cavern in these mountains.