[1][2] Gravel beds within the formation in the Rio Puerco valley west of Albuquerque have provided clues to the paleogeography of the Grants area since the early Miocene.

The Cerro Conejo Formation is composed of very light brown to pink or yellowish-red, fine- to medium-grained, well-sorted, medium- to thick-bedded sandstone.

[4] Gravel beds within the formation in the Rio Puerco valley west of Albuquerque have provided clues to the paleogeography of the Grants area since the early Miocene.

[5] The formation has yielded vertebrate fossils at the Rincon and Zia quarries that are characteristic of the middle to late Miocene (Barstovian to Clarendonian).

It was named for exposures along Arroyo Ojito near Cerro Conejo, a small hill northwest of Albuquerque.