Underwater Excavation

Gormanston Landfall, Co. Meath: Prehistoric Logboat

ADCO was appointed to monitor the dredging activity associated with the landfall for the GAS 2025 Irish Sea Interconnector pipeline as it approached the east coast at Gormanston, Co. Meath.

It was necessary to cut a pipe trench 40metres wide and up to 5metres deep below existing seabed level, over a distance of 4km from sea to shore. Preparatory assessment did not indicate any archaeological material along the proposed pipeline route, but the records of more than 40 boat- and shipwreck sites in the vicinity dating from the 1600s suggested that this was an area of high potential.

A programme of 24-hour monitoring was carried out during the works project over two months at the request of the state authority, to record the type of seabed material that was being excavated. The dredging was undertaken by the Irish Dredging Company Ltd. using two separate platforms: a working barge, the Manu Pekka, was used for inshore work, while a trailer suction hopper dredger, Medway II, completed the dredging out to sea.

ADCO personnel maintained a record of position and dredging area, and observed the actual dredging, noting dredge depth, progress of dredging, and any items of interest.

At 20:30 hrs on 02 June, seven timbers were retrieved by the backhoe dredger. The timbers were all retrieved from the same location. It was apparent that further remains lay within the seabed. The discovery had occurred while dredging was removing the upper two metres of seabed. A ridge of undredged material remained across the c. 50m-wide trench in this location. A dive operation was undertaken to inspect the location

The wrecksite was loccated at 53° 38.917’N 06° 12.41086’W, or NGC 318622E 268012N. It was evident that a large piece of wreckage remained on the seabed. A second dive operation was carried out to clear the 2m of overburden at the undredged portion, and to remove the timbers from the seabed. It was estimated that this work would take nine days to complete. In the event, the work was completed ahead of schedule on 22 June, after six days of site work.

The excavation opened a cutting c. 6m x 5m over the buried portion, and removed the sand with suction dredges. The wreckage was identified, planned, recorded, and lifted from the seabed, and dredging proceeded without interruption to the overall schedule.

The archaeological data recovered represents an important discovery. It constitutes a logboat, or dug-out canoe, that measured 7m in length and is the first such discovery in Ireland from an active marine environment. This boat represents the clear evidence for the first time that early man plied the coastal waters in such fragile craft, which presumably were used to ferry people and supplies along the coast.

The boat is currently being conserved at the Mary Rose Trust in England, and a date is expected from a sample taken for Carbon 14 analysis.

Other Projects

Environmental Impact Assessment

Intertidal Survey  

Geophysical Data Interpretation

Monitoring

Underwater Excavation

Heritage Management and Research