[1][2][3] The formation consists of uniform, very well sorted, fine-grained pink to buff sandstone with lesser amounts of shale and siltstone.

The sandstone is highly bioturbated and in some place shows ripple marks and low-angle crossbedding.

The formation has few faunal fossils, but the age is likely late Turonian to early Coniacian.

Sears originally defined the Gallup Sandstone as the three sandstone beds, separated by shale and coal beds, forming cliffs and hogbacks in the Gallup area[1] Pike first observed in 1947 that the member intertongues with the Mancos Shale (Pescado Tongue).

[5] The unit has since undergone repeated revisions,[6] with the most recent revision by Nummedal and Molenaar in 1995 removing the fluvial Torrivio Member and restricting the formation to the basal 71 meters (233 ft) of marine sandstone of the Mesaverde Group.