Promontory fort - coastal, Béal Deirg Mór, Co. Mayo
Co. Mayo |
Forts
At Béal Deirg Mór on the north-facing Mayo coast, a long finger of land juts out into the sea with nothing on it.
No walls, no structure, no visible entrance. What makes it a fort, at least in the archaeological sense, is a single cut in the earth: a fosse, or defensive ditch, six metres wide and round-bottomed, drawn straight across the narrow neck of the promontory and effectively severing this slender 80-metre tongue of land from the mainland behind it. A promontory fort works on the principle that the sea does most of the work, with a headland's natural flanks providing defence on the exposed sides, leaving only the landward approach to be blocked. Here, that blocking is reduced to its barest possible form.
The site sits in hilly bogland, with higher ground rising to the south, and gullies carrying streams down either side of the headland. The fosse itself is still visible, though a later earthen field fence running along its outer edge has obscured whatever counterscarp bank, the raised outer lip of a ditch, may once have stood there. Just inside the fosse, a rise of roughly a metre in the ground surface is all that survives of any internal bank. Beyond that, the interior gives nothing away. There is no trace of structures, no identifiable entrance, and the surface offers no obvious clue as to who built it or when it was last used. Promontory forts of this kind are found all along the Irish Atlantic seaboard, and while many are assumed to date from the Iron Age, precise dating at unexcavated sites remains difficult.