English: Figure 111 from The Geology of the Richmond Basin published by USGS, which has the following caption:
Surface of a fragment of shale from Midlothian, after layer of coal with calcite veins has been removed, showing lines of grooves marking edges of the veins.
The text of the report refers to the figure as follows:

Markings on shale due to vein structures.—The thin laminae of coal in the Midlothian field are sometimes minutely jointed, and these closely set gaping joints have been filled with veins of calcite. The overlying and underlying layers of shale frequently bear incised lines marking the sharp edges of these veins, in the manner already described in the case of veins seen in cross section near Winterpock. These markings are creases or grooves rather than fractures in which the veinstone original formed. These creases, which stimulate mud cracks and ice crystal marks, indicate the compression of the shale upon the coal, the sediments yielding, while the veinstone resisted the movement (see fig. 111). The slight compression indicated by these lines may be accounted for by the weight of the overlying beds, though the joints may have been initiated by torsion and displacement.