mapped the Permian redbeds of the Chama Basin as Abo Formation in 1928. In 1946, Wood and Northrop mapped the Pennsylvanian-Permian red beds north of latitude 36 degrees as Cutler Formation and south of that latitude as Abo Formation. It was not until 2005 that the lithology of these beds was well enough characterized for it to be raised to group status and divided into the lower El Cobre Canyon Formation and upper Arroyo del Agua Formation by Lucas and Krainer in 2005. Footnotes See also List of fossiliferous stratigraphic units in New Mexico Paleontology in New Mexico References Further reading Permian formations of New Mexico