Bisbee Group

The Bisbee Group is a geologic group in Arizona, Mexico, and New Mexico. It preserves fossils dating back to the early Cretaceous period.
Description.
The group consists of sandstone, claystone, limestone, and conglomerate, with a total thickness of . In the Tombstone, Arizona, area, it overlies the Naco Formation. In the Bisbee area, the group is divided into four formations, which in ascending stratigraphic order are the Glance Conglomerate, the Morita Formation, the Mural Limestone, and the Cintura Formation. The group is overlain by the Bronco Volcanics, the Nipper Formation, or the Faraway Ranch Formation.
In southwestern New Mexico, the group thickens to and is divided into the Glance Conglomerate, the Hell-to-Finish Formation, the U-Bar Formation, and the Mojado Formation.
Fossils.
The group contains fossils such as the mollusc "Exogyra" and the clam "Trigonia" characteristic of the Cretaceous.
History of investigation.
The Bisbee beds were first named by E.T. Dumble in 1902 for exposures around Bisbee, Arizona. In 1904, Frederick Leslie Ransome divided the Bisbee Group into formations in the Bisbee area. By 1938, the group had been mapped into the Tombstone, Arizona area and into southwestern New Mexico. Samuel G. Lasky defined several new formations within the group, but some of these were synonyms for each other due to fault doubling.