Named for exposures in Sullivan Buttes, the type locality, northwest of Prescott in the Simmons quad, Yavapai Co, AZ, Basin-and-Range province. Geologic map. Mapped on Sullivan Buttes and to east on Granite Creek in the Prescott and Paulden quads, and as four separate small bodies, three in the Prescott quad, and one in the Paulden quad. The latite has biotite and hornblende. Chemical analyses. Consists of plugs, breccias, agglomerate, and mudflows and latitic gravels. Considered younger than some Tertiary gravels and older than the Hickey Formation. Two samples dated by K-Ar method yielded ages of 26.7 +/-1.1 and 23.4 +/-1.0 m.y. Assigned a late Oligocene? and early Miocene age.

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