[1] The formation is the most widely exposed Paleozoic formation in the state of New Mexico, cropping out in a zone 80–110 kilometers (50–68 miles) wide that extends from west Texas to central New Mexico and with additional exposures in the Zuni Mountains and Sangre de Cristo Mountains.

[5][1] The formation contains fossils of the gastropod Euomphalus, the scaphopods Plagioglypia canna and Dentalium mexicanam, and the bivalve Aviculipinna.

Lee mistakenly concluded that it contained fossils indicating a Pennsylvanian age and added the formation to the Manzano Group, designated a type area at the northern end of the San Andres Mountains.

[9] By 1937 the San Andres was being recognized as an important unit in the subsurface in eastern New Mexico and west Texas.

[11] Needham and Bates formally designated a type section in 1943, at the same time removing the Glorieta Sandstone from the formation.