Keystone Over Thrust Fault, Red Rock Canyon, Nevada - Grey Colored Limestone And Dolomite From About 440 Million Years Ago Has Been Thrusted Over Red Colored, 65 Million Year Old, Aztec Sandstone By Plate Tectonics. The Fault Line Called The Keystone Thrust, Runs At Top And From Left To Right Between The Grey Colored Limestone At Top And The Red Colored Rock Directly Below It. Photo