[1] The Sandia Formation is mostly shale with some sandstone and conglomerate but only minor limestone beds, with the coarser sediments towards its base.

[1] The formation reaches its maximum thickness of 1,530 meters (5,020 feet) in the northern Sangre de Cristo Mountains, where its great inhomogeneity both laterally and vertically indicates a complex marine and nonmarine depositional environment.

[2][3] It is found in the Sandia, Jemez,[4] Sangre de Cristo,[3] and Manzano Mountains[1] as well as the Las Vegas Basin.

[1] The exposures at Priest Canyon in the southern Manzanos include Syringopora and the demosponge Chaetetes.

Armstrong also noted that the zone immediately above the Log Springs Formation was characterized by fossils of the early Pennsylvanian brachiopod Schizophoria oklahomae and was separated from younger beds by an erosional discontinuity.