Earthworks situated to the northeast of Marian Ffrith are found to the west and south of Marian Mawr. These features include grass-covered mounds, which are visible in several locations. Notably, they appear in the field south of the lane, adjacent to the track leading to Ochr-y-Marian. Additional mounds can also be seen in the fields to the west of Plassau, at grid reference SJ 0790 7820.