Baca Formation


The Baca Formation is a geologic formation in southern New Mexico and Arizona. It preserves fossils dating back to the Eocene period.

Description

The formation consists of coarse conglomerate, red and white sandstone, and red clay. Its total thickness is, of which is conglomerate. The formation rests unconformably on the Mesaverde Group and is overlain by the Oligocene Spears Formation.

Fossils

The formation is relatively poor in vertebrate fossils, and only six of biostratigraphic significance have been found. These are the titanotheres Paleosyops and Manteoceras, an artiodactyl trackway and Protoreodon fossil, and a small mammalian fauna at Mariano Mesa. The titanotheres are characteristic of the Bridgerian age while the trackways indicate a late Eocene age or younger.

History of investigation

The formation was first described by Wilpolt et al. in 1946 and named for exposures in Baca Canyon in the Sacramento Mountains.

Footnotes