Promontory fort - coastal

The National Monuments Service's description

Located in the NW corner of Dalkey Island. A promontory fort encloses an area (0.25ha) which is roughly divided into two flat platforms. A low oval N-facing promontory surrounded by a rocky shore measuring 50m N-S is defended on the landward side by a curving 6m wide 1m deep U-shaped fosse and intermittent traces of a low internal earthen mound close to the E shore, possibly the remains of a bank or wall. The interior consists mainly of outcropping rock and coarse vegetation, with access to the sea possible from all sides. The fosse is deepest along the E, diminishing to the N 8m from the W edge, possibly the site of a causewayed entrance. To the S the site is overlooked by higher ground occupied by a Martello tower. A gun emplacement was built on the S shore, while a 7th-century church dedicated to St. Begnet stands on the northern slopes inland from the fort. Sea rocks extending 100m from the site suggest the headland was once larger. These defences were excavated by Liversage in 1957 (1968, 99-104). The fosse had been steep-sided (Wth 5m; D 2.4m) and its fill produced animal bones and iron slag. It had been a source of building material for the external bank (Wth 8.5m; H 1.4m).
Compiled by: Geraldine Stout and Padraig Clancy
Revised upload on: 25 June 2018.

References

Liversage, G.D. 1968 Excavations at Dalkey Island, County Dublin 1956-1959. Proceedings of the Royal Irish Academy 66C, 53-233.

Casey, M. 2003 The coastal promontory forts of Ireland: interim report for the Heritage Council. Unpublished specialist report, National Monuments Service, Department of Arts, Heritage and the Gaeltacht.