[4][5] The formation is composed most of massive gray fossiliferous limestone with some shale and sandstone, with a thickness in excess of 5,000 feet (1,500 m).

It overlies the Panther Seep Formation[6] with a slight disconformity, and its base is typically a thick biostromal limestone bed.

[5] In the Robledo Mountains, the Hueco is promoted to group rank and divided into (in ascending stratigraphic order) the Shalem Colony, Community Pit, Robledo Mountains, and Apache Dam Formations.

[1] Nelson dated the formation as earliest Permian in the Franklin Mountains in 1940.

[4] Spencer G. Lucas et al. promoted the formation to group rank in 1998.