Stratigraphy and correlation of the Lower Permian Hueco Group in the southern San Andres Mountains, Dona Ana County, New Mexico
— Spencer G. Lucas, Karl Krainer, and Barry S. Kues

At Little Wells in the southern San Andres Mountains a complete and well exposed section of the Lower Permian Hueco Group is 517 m thick and conformably overlies the Panther Seep Formation and is conformably overlain by the Abo Formation, The Hueco Group strata here are assigned to three formations (ascending order): (1) Shalem Colony Formation, 119-m thick, mostly shale and relatively thick ledges of wackestone that are characteristically cherty and coarse grained; (2) Community Pit Formation, 140-m thick, mostly shale and thin ledges of wackestone and lime mudstone that lack chert and are typically orange or yellow in color; and (3) Robledo Mountains Formation, 258-m thick, mostly shale with intercalated thin beds of red bed sandstone and wackestone limestone. Microfossils from these Hueco Group strata include calcareous algae, non fusulinacean and fusulinacean foraminifers and ostracods; macroinvertebrate fossils are mostly brachiopods and gastropods. Tetrapod footprints and the conifer Walchia are common fossils in the Robledo Mountains Formation. Correlation of the Hueco Group section at Little Wells across the Rio Grande rift to the Robledo Mountains is relatively straightforward and indicates continuity of Early Permian lithofacies across the western Orogrande basin.