Named as the upper member of the Skinner Ranch Formation (new) for Sullivan Peak, Brewster Co, TX in Permian basin. Type section designated in ravine east-southeast of Hill 5300 in the central Lenox Hills, Altuda 15 min quad. Is 120 ft thick in the type measured section where it consists of (ascending): thick-bedded detrital limestone with productid brachiopod SPYRIDIOPHORA; limestone conglomerate with boulders as much as 4 ft in one dimension; thin-bedded limestone and pinkish-brown chert; thick-bedded massive conglomeratic limestone with large limestone and quartz pebbles; thick-bedded fine-grained brown sandstone and sandy limestone in layers 2 inches to 1 ft thick. Overlies Poplar Tank Member (new) of Skinner Ranch. Underlies Cathedral Mountain Formation (new). Can be distinguished from Lenox Hills east to Hill 5300 where the underlying Poplar Tank tongues out into the Skinner Ranch and the Skinner Ranch is an undivided unit. Was called "First limestone member" of Leonard in earlier reports. Cross section. Of Leonardian, Early Permian age.

Source: GNU records (USGS DDS-6; Denver GNULEX).