When the Ordnance Survey recorded the area on its six-inch sheets in 1838, the crossing appeared as a relatively modest feature, roughly forty metres long and between twenty and twenty-five metres wide. By the time the same area was mapped again in 1930, that narrow link had apparently broadened to a spread of stones some sixty-five metres wide. The island it leads to is not especially small, running approximately four hundred metres on its longer axis and around a hundred and twenty metres across.

The most likely explanation for the apparent widening is not construction but subtraction. Lake water levels at Lough Conn have dropped over time, and as the water has retreated it has exposed more of the stony bed between shore and island, turning what was once a submerged or barely-visible structure into something considerably more substantial in outline. The causeway itself may be ancient, the kind of deliberate stone crossing built to give access to an island that would otherwise require a boat, but the record does not establish when it was made or by whom. What the two maps together do capture is a slow-motion process of emergence, the same stones becoming a broader feature not because anyone added to them, but because the lake around them quietly withdrew. The area of dry ground has continued to expand and is now covered in scrub, which obscures whatever structure lies beneath.