Named for the reference section on the Houy Ranch in southeastern Burnet Co, TX on the Llano uplift. Type section designated along Burnam Ranch where it enters Doublehorn Creek in southeastern Burnet Co. Occurs in central TX. Principal subdivisions (ascending order) are: Ives Breccia Member, Doublehorn Shale Member (new), and a locally occurring thin unnamed phosphoritic interval. Commonly one or more of these members is absent, and at some localities, rocks not assigned to any member. Consists of 1-3 ft of chert breccia, the Ives Breccia Member; 2-15 ft of black, fissile shale, the Doublehorn Shale Member; and 2 ft or less of phosphoritic material. Total maximum observed surface thickness is 17 ft. Four conodont zones recognized in the Houy Formation; conodonts listed. Measured sections described at the type section (Burnam Branch) and at the principal supplementary section (Houy Ranch) on the Rubin Houy ranch which is along Doublehorn Creek just downstream from Houy Branch and 1.5 mi south-southwest of the type section. Geologic maps. Columnar sections. Underlies Chappel Limestone; overlies Ordovician Honeycut Formation at some localities, and Devonian Stribling Formation at other localities. "Beds included are mainly Upper Devonian, but partly Lower Mississippian."

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