Streams entering the shallower waters deposited mud and sand which later consolidated into shales and marine sandstones. Changing land and sea levels trapped large bodies of water which later evaporated leaving behind layers of salt and gypsum in some areas. Exposure of the sediments to the atmosphere allowed some of the minerals to oxidize, resulting in red and orange colored rocks. Streams meandering across the broad plain deposited sand, mud, gravel and other debris such as logs. In some cases, minerals in the groundwater replaced the organic materials in the buried logs forming petrified wood.
Petrified wood is one of the few fossil remains found in the rocks at the foot of the cliffs.
About 180 million years ago the area was completely arid, much as the Sahara Desert is today. These shifting sands were buried by other sediments, and eventually cemented into sandstone by iron oxide with some calcium carbonate. This formation, known locally as the Aztec Sandstone, is quite hard and forms the prominent cliffs of the Red Rock escarpment. In some areas the iron minerals in the rocks have been altered and concentrated giving the rock its red color. The most significant geologic feature of Red Rock Canyon is the Keystone Thrust Fault.