English: Plate XXI from The Geology of the Richmond Basin published by USGS, which has the following caption:
Disintegration of granitite on eastern border (of the Richmond Basin), in Southern Railway cut, near Midlothian. A similar condition of the rock preceded deposition in Newark time.
The text of the report refers indirectly to the figure:

THE BOSCABEL BEDS

Bowlder deposits, believed to be associated with the Newark rocks, are found at two points on the western margin, north of the James River. Heinrich reports their existence at the base of the formation, at Midlothian, on the eastern margin; but such deposits have not been discriminated at the surface in that district. It may be that the large granitic blocks left upon the granitic area at the border line by atmospheric decay form a part of this layer, but there is no proof to that effect.

The bowlder deposits along the western margin are best exposed at Boscabel Ferry, in a small area separated from the main basin at Manakin by the gneissic ridge of Cornwallis Hill. The deposit consists of subangular fragments of gneiss of various origins. While a few of the fragments are rounded, others show almost unabraded joint faces. Flat blocks 3 feet long and 2 feet wide, and even 4 feet long, occur in pell-mell disorder, with a partial bedding of reddish gritty sandstone.