It preserves fossils dating back to the late Cretaceous period.

[1] A single latite tuff bed some 20 feet (6.1 m) is exposed in the formation.

[1] The formation was deposited in the Little Hat Top basin, which was produced by Laramide deformation on the southwest flank of the Hidalgo uplift.

[3] The formation was first named by Zeller and Alper in 1965 for a single outcrop in the Animas Mountains.

[1] By 1970, it had been traced into southeastern Arizona[2] Elston and Erb recommended merging the formation with the overlying Timberlake Formation due to lack of a clear lithological distinction,[4] but this has not been universally accepted.