Most of the Culpeper Group conglomerates are exposed along the western margin of the Culpeper basin. These rocks are mostly muddy to sandy pebble conglomerates, and are interpreted as debris-flow deposits. Isopleths of maximum clast size show a decrease in grain size toward the east; this and paleocurrent data indicate that the conglomeratic materials were deposited on alluvial fans which spread eastward from highlands developed on the upthrown block west of the normal fault which borders the Culpeper basin on the west.

Pre-Triassic rock in the north-plunging Blue Ridge anticlinorium west of the basin was the source for gravel deposited on the fans. Spatial relations between the eastern limb of the anticlinorium and the border fault greatly influenced the composition of the gravels. The border fault generally has a more easterly strike than the pre-Triassic rock units. Pre-Triassic units intersect the fault so that progressively older rocks are exposed toward the south. From north to south the conglomerates contain clasts produced by erosion of progressively older rocks in the east-dipping limb of the anticlinorium.

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