By then, it had become part of a large desert with shifting red sands and huge dune fields. These sand dunes left their marks in the rocks and cliffs. Visitors today can see evidence of the fossilized dunes preserved in the sandstone. Beginning approximately 65 million years ago the earths crust was again changing this area. A large system of thrust faults extending south and as far north as Canada developed.
Thrust faults result in some rather unusual effects.
This particular thrust fault created one of the most interesting features of Red Rock Canyon, the Keystone Thrust. Here older layers of rock were 'thrust' over younger layers of rock. Geologically this is unusual. Visually, it is striking. More recently, the ancient Anazasi left their mark on some of the rock faces in the form of petroglyphs.