The Red Rock Canyon National Conservation Area is located just a few miles west of Las Vegas and encompasses 197,000 acres within the Mojave Desert. Red Rock is an area of world wide geologic interest and beauty. The most significant geologic feature of Red Rock Canyon is the Keystone Thrust Fault. A thrust fault is a fracture in the earth's crust where one rock plate is thrust horizontally over another. About 65 million years ago, it is believed that two of the earth's crustal plates collided with such force that part of one plate was shoved up and over younger sandstones. This thrust contact is clearly defined by the sharp contrast between the grey limestones and the red sandstones. The Keystone Thrust Fault extends from the Cottonwoood Fault (along the Pahrump Highway) 13 miles northward to the vicinity of La Madre Mountain, where it is obscured by more complex faulting.