Based on ammonite biostratigraphy, the age of the Menefee Formation can be constrained to 84.2-79 million years (Ma), based on the presence of Baculites perplexus in the overlying Cliff House Sandstone, and ammonites from the late Santonian in the underlying Point Lookout Sandstone.

The Menefee Formation was deposited at the peak of the regression as coastal river delta and swamp sediments, and includes numerous coal beds.

[2][3] The formation is exposed at Chaco Canyon National Park, where many of the coal beds have been burned to produce distinctive red cinder outcrops.

[4] The Menefee Formation includes fossils of turtles, fish and crocodiles and fragmentary evidence of hadrosaurs, ankylosaurs, and ceratopsian dinosaurs.

Plant fossils include leaf impressions of palms, conifers, laurels, witchhazel, and camellia.

[5] Several vertebrates have been recovered from the Menefee Formation, including intermediate remains of baenids, trionychids, and dromaeosaurids.

[7] Indeterminate[7] A scapula, metatarsal, shaft of anterior thoracic rib, postorbital and lateral tooth.

[13] The Monero field in Rio Arriba County, New Mexico, was mined from the 1880s into the early 1920s to support the Denver and Rio Grande Western Railroad, but while the coal is of good quality, the coal beds are relatively thin and the terrain is rugged.