But the curved line of this low mound, sitting roughly forty-six metres south-southwest of the early medieval church known as Temple Cronan, may preserve the outline of something far older: the original ecclesiastical enclosure that once defined the sacred precinct of one of the Burren's most significant early Christian sites. Such enclosures, roughly circular or oval banks that marked the boundary of a monastic or church settlement, were a common feature of early medieval Irish Christianity, delineating the spiritual and legal territory belonging to a religious community.

Fieldwork carried out before 1982 first brought this feature to wider attention, when J. Sheehan noted the discovery of an enclosure around the site at Termon. The place-name itself is telling: "termon" derives from the Latin "terminus" and in an Irish ecclesiastical context it denotes land under the protection of a church or saint, ground that carried certain legal immunities in early medieval law. The boundary bank, measured at four metres wide with an internal height of around 0.65 metres and an external height of just over a metre, follows a curved alignment consistent with the kind of enclosure that would have surrounded an important early foundation. Temple Cronan itself is associated with St Cronan of Roscrea, and the site retains the remains of a small Romanesque church that points to activity here from at least the twelfth century, if not considerably earlier.