It curves in a distinctive semi-oval, and it is precisely this outline that has led researchers to suspect something far older lies beneath the familiar surface of the site.

Early Christian ecclesiastical enclosures, typically dating from roughly the sixth to the twelfth centuries, were often defined by a curving or circular boundary, a form thought to reflect both symbolic and practical traditions of sacred space in early medieval Ireland. When a later graveyard or church is planted within or over such a site, that original curve can survive in the landscape long after everything else has been obscured or built over. At Mayne, the semi-oval form of the graveyard boundary wall was identified by Leo Swan in 1988 as a possible indicator of just such an enclosure beneath. Swan was a pioneering figure in the study of these sites, and his 1988 survey work helped bring attention to how much early ecclesiastical geography could be read from aerial photography and ground-level observation of field boundaries and graveyard walls.