Visible on the ground and on APs (1), SW of the summit of Mynydd Brombil, is a broad curvilinear bank. As a prominent earthwork it has a length of c.120m following a NW direction from near a field wall before sweeping round to the NE and facing a farm building near the summit. At its most prominent it has a width of 8m and height of 0.4m. Faint traces of a bank parallel to the nearby modern boundary were seen.
The feature is hard to explain in terms of a simple field boundary. It lies in what was part of the Margam Estate, and may be connected with land-use activity which included the nearby pillow mounds.
