One is roughly circular, about two and a half metres across and less than a metre deep, sitting along the north-western edge of a cashel wall. The other runs southward from it, a narrow stone-filled channel roughly six metres long and just over a metre wide. Together, they are thought to mark the remains of a souterrain, an underground passage or chamber built into or beside an early medieval enclosure.

Souterrains were dry-stone-lined tunnels, occasionally corbelled into small chambers, typically associated with ringforts and cashels across early medieval Ireland. A cashel is a type of stone-walled enclosure, broadly equivalent in function to an earthen ringfort, used to define and defend a farmstead or settlement. Their souterrains served various purposes, possibly storage, refuge, or ventilation for internal structures, and the precise use of any individual example is rarely easy to determine. At Keeloges, the collapsed and stone-filled state of the channel and the shallow bowl of the probable entrance depression suggest the structure has not been open or accessible for a considerable time. The site is recorded in Michael J. Moore's Archaeological Inventory of County Leitrim, published in 2003, which places it in direct association with the adjacent cashel on the same hillock.