The Catharpin Creek Formation of the Culpeper Group in Virginia is here named. The unit was originally part of the informal Catharpin Creek member of Lee (1979, 1980) of the Bull Run Formation. The member included the entire sequence of sedimentary rocks enclosing and intercalated with the basalt flow units. The name Catharpin Creek is retained for the lowest sedimentary unit; the upper sedimentary units are named the Midland, Turkey Run, and Waterfall Formations. The Catharpin Creek consists or red, micaceous, pebbly feldspathic sandstone and clayey siltstone, with local conglomerate lenses. It includes the Goose Creek Member at the top. Gradationally overlies and intertongues with the Balls Bluff Siltstone; underlies the Mount Zion Church Basalt with a sharp disconformity. Thickness may be as much as 500 m (1,660 ft). The Triassic-Jurassic boundary occurs in the upper part of the unit.

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