It has no visible fosse, which is the defensive ditch that usually encircles enclosures of this kind, and no identifiable entrance. What it does have, sitting inside its southwestern edge, is a natural spring called Major's Well. The combination of a substantial earthen boundary and an enclosed spring, with no obvious military or agricultural logic to explain the layout, gives the site a quality that is easier to notice than to account for.

The enclosure was recorded as circular on the first edition Ordnance Survey six-inch map of 1839, with an external diameter of around 100 metres. By the time the 1940 edition was surveyed, it was being described as oval, with dimensions of roughly 150 metres north to south and 100 metres east to west, suggesting either that earlier surveyors simplified its shape or that the perimeter had shifted in interpretation over the intervening century. On the ground today the visible area measures approximately 100 metres on its northeast to southwest axis and 60 metres across, defined by low scarps rather than any pronounced bank or ditch. The scarp along the southwestern side is the more substantial of the two, reaching about a metre in height and nine metres in width. The perimeter has been absorbed into a field boundary along the southwest and west, and cut through by a later field bank to the northeast, which has obscured part of the original form. A ringwork, a type of enclosed medieval fortification usually consisting of a raised platform surrounded by a ditch and bank, lies roughly 100 metres to the northwest, hinting that this corner of Great Island carried some significance across more than one period.