The base of the outcrop has been scarped, meaning the natural stone was cut back and shaped, to produce a flat-topped platform roughly 35 metres across east to west and 21 metres north to south, defined by a scarp about a metre high. It is an earthwork in the technical sense, a deliberate reshaping of the landscape for enclosure or ceremonial purpose, though what exactly was enclosed here and when remains quietly open.

The early Ordnance Survey mapping of the nineteenth century recorded the site as a circular earthwork, with no structure inside it. By the time later editions were produced, a church had appeared within the enclosure, and the wall-footings of that building are still visible at the centre of the platform. A holy well lies a short distance to the north. This clustering of features, an ancient shaped enclosure, a later church, a sacred spring, follows a pattern seen repeatedly across early Christian Ireland, where ecclesiastical communities settled into or beside pre-existing enclosures, borrowing their boundary and perhaps their significance. Whether the scarped platform at Coogulla is the remnant of an early medieval ecclesiastical enclosure, or something older still, is not something the surviving evidence settles clearly.