After further study and identification of this area as a quarry, it appears that this is one of a series of cuts into the bedrock associated with quarry machinery. This one, specifically, may have accommodated one of the posts to which cranes’ tie-rods were tied

Possible posthole cut because of the square shape and absence of anthropogenic material. The erosion of the bedrock (SU1) is significant in this part of area A, therefore this posthole may have been more substantial, but little is preserved now.