Menefee Shale

The Menefee Shale is a geological stratum underlying the Chaco Wash, which is located in the northwestern portion of the U.S. state of New Mexico, in what is now Chaco Culture National Historical Park. The Chaco Wash flowed across the upper strata of what is now the 400-foot (122 m) Chacra Mesa, gouging out a broad canyon over the course of millions of years and exposing bedrock comprising the Menefee Shale formation; this was subsequently buried under approximately 125 feet (38 m) of deposited sediment.