Causeway

The National Monuments Service's description

On the S and SE side of Garret Island in Lough Gur on shallow reefs underwater. The island is 150m NW of the Knockadoon peninsula where extensive archaeological excavations have uncovered significant Neolithic and Bronze Age archaeological monuments (Cleary 2018). Prehistoric settlement is present on the island (LI032-016/017/019----). The archaeological features (LI032-021----) were recorded by archaeologists and antiquarians working around the lake (Harkness 1869, 395-6, O’Kelly 1944, 28; Ó Ríordáin 1954, 459).
The island is depicted on the 1840 ed. OSi 6-inch map as a circular island (ext. diam. 30m) known as Garret Island. The surface of the island was recorded 1m above the lake level in 1840 (76.8m OD). The island is later depicted as a significantly larger area (170m N-S; 65m E-W) on the OSi 1897 ed. 25-inch map, the lake level is recorded 1.5m lower in 1897. The lake level today remains at c. 75m OD. The excavations on the island by Liversage and Mitchell (1958) have demonstrated that the lake level was lower in prehistory, possibly even lower than it is today and that the current foreshore was the location of a Bronze Age forest that was submerged.
Harkness (1869, 396) records that a substantial quantity of animal bone (incl. a small quantity of human bone) was left exposed on the old lake bed around the island after the lake was drained in the mid-19th century. The finds collected from the newly exposed foreshore included stone axes, bone pins and other artefacts. Harkness (1869, 395) also refers upright timber piles forming a causeway to the island from Knockadoon. It is possible that the timber piles in the lake referred to by Harkness are the remains of prehistoric tree stumps on the shallow lake bed SE of the island, such as those revealed by archaeological excavations (LI032-217----) preserved in the silt, mud and lakewater (Liversage 1958, 69). Ó Ríordáin (1954, 459) refers to a dugout canoe on the lake bed between the SE end of the island and peninsula, he also makes passing reference to ‘timber piles…near the Knockadoon shore’. The island and the shallow reefs to the S of it are visible in the summer when the water level is lower and light conditions permit, see Google Earth orthoimage taken 28/06/2018, the water level is shallow enough to see the geological fissures in the rock on this image. The reef is not visible on the most recent orthoimage taken 20/09/2020.

See attached Google Earth orthoimages

Compiled by: Edmond O’Donovan

Date of upload: 2 November 2020

References

O'Kelly, M.J. 1944 A survey of the antiquities in the barony of Small County, Co. Limerick. North Munster Antiquarian Journal 4, 16-53.

Cleary, R. 2018 The archaeology of Lough Gur. Dublin. Wordwell.

Harkness, R. Prof. 1869 The prehistoric antiquities of and around Lough Gur. Quarterly Journal of Science, 388-96.

Liversage, G. D. 1958 An Island Site at Lough Gur. Journal of the Royal Society of Antiquaries of Ireland, 88, (1), 67-81.

Ó Ríordáin, S.P. 1954 Lough Gur excavations: Neolithic and Bronze Age houses on Knockadoon. Proceedings of the Royal Irish Academy 56C, 297-460.