An overview and delineation of the Cuchillo geomorphic surface, Engle and Palomas basins, New Mexico
— David J. McCraw and David W. Love

The Cuchillo surface satisfactorily meets the defining criteria of a geomorphic surface, i.e., distinct landscape position, finite age, uniformity in degree of soil development, and defined geography within local rift basins. Its planar-concave-up surface formed at the cessation of Palomas Formation aggradational deposition at ~0.8 Ma, modern surface remnants generally slope only 1-2° (with few exceptions), and have a grade of ~90 m above the modern floodplain of the Rio Grande. It consistently exhibits mature soils with thick argillic Bt horizons overlying petrocalcic stage III-IV K horizons with depths commonly exceeding 1.5 m. As the overall distribution of the Cuchillo surface has never been adequately mapped, a proposed delineation using sophisticated digital mapping tools is presented here. The Cuchillo surface covers much of the Engle and Palomas basins, extending from just south of the San Jose Canyon fan to just north of Berrenda Creek and from the hanging wall margin of the Sierra Cuchillo and Black Range to the footwall escarpments of the Fra Cristobal Mountains and the Caballo Mountains, including paleofans above the Apache Valley.