Exposures of red shale at Bull Run, VA, are here named the Bull Run shales. Unit includes all of the red shales and sandstones of Late Triassic age that occur in belts up to 4 mi wide from north to south in the Potomac, Scottsville, Richmond, Farmville, Danville, and Taylorsville areas in VA. Color varies from red to gray, blue, black, and decolorized near igneous rock contacts. Overlies Manassas sandstone.

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

The Bull Run Shales of Roberts (1928) is revised to Bull Run Formation of the Newark Group and is divided into the lower Leesburg Limestone Conglomerate Member which grades into and intertongues with the upper basaltic-flow-bearing clastics member. This member forms the bulk of the formation in the west-central part of the basin where it consists of a heterogeneous mixture of conglomerate, sandstone, siltstone, shale, and locally, coal and limestone, interbedded with three basalt flows. Thickness ranges from 190 to 7,930 m (630 to 26,200 ft). Age is Triassic and Jurassic(?).

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

The Bull Run Shales of Roberts (1928) is revised to Bull Run Formation of the Culpeper Group and includes the sequence of rocks that conformably overlies the Manassas Sandstone and underlies the lowermost basalt flow of the Buckland Formation. It consists of massive, cross-bedded, and laminated red mudstones and siltstones with intercalated shale, sandstone, and conglomerate lenses. It contains the Leesburg Conglomerate, Goose Creek Conglomerate, Cedar Mountain Conglomerate, and Barboursville Conglomerate Members. Maximum thickness is 5,100 m (16,800 feet). Age is Late Triassic and Early Jurassic.

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

The Bull Run Formation or Shale is here abandoned because in all previous definitions this heterogeneous unit lacked distinctive boundaries. The basalt and interbedded sedimentary units equivalent to or included by Roberts (1928), Lee (1977, 1979, 1980), and Lindholm (1979) in the Bull Run are here assigned to the Culpeper Group and are named the Balls Bluff Siltstone and its Leesburg Member, Tibbstown Formation and its Mountain Run and Haudricks Mountain Members, Catharpin Creek Formation and its Goose Creek Member, Mount Zion Church Basalt, Midland Formation, Hickory Grove Basalt, Turkey Run Formation, Sander Basalt, and Waterfall Formation and its Millbrook Quarry Member. Lindholm's Cedar Mountain and Barboursville Conglomerate Members of the Bull Run Formation and his Buckland Formation are here abandoned.

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