[3] The group consists of sandstone, claystone, limestone, and conglomerate,[1] with a maximum thickness of 1,770 meters (5,810 ft) in the Chiricahua Mountains.

This rift belt was located between the Mogollon Highlands of central Arizona and New Mexico, which formed the northern shoulder of the belt, and Cordilleran (or Alisitos) volcanic arc along what is now the western side of the Gulf of California.

The third and largest incursion formed the lagoon belt of the Arroyo Sásabe Formation and the marine Mural Limestone.

[1] The limestone formations contain fossils of scleractinian corals from a diversity of genera, including several species not found elsewhere.

[9] Samuel G. Lasky defined several new formations within the group, but some of these were synonyms for each other due to fault doubling.