1997:198 - GALWAY: Custom House, Court House Lane, Galway

Pre-development testing was undertaken on the site of a proposed extension to the Custom House off Court House Lane, Galway, between 18 and 26 March 1997.

It is generally believed that the area in and around the Custom House was the location of the original Dún or earthen fortress called Bun Ghaillimhe, built c. 1124. In 1232 a new and more substantial building, a stone castle, was built on the site of the Bun Ghaillimhe by Richard de Burgo. In 1271 Richard de Burgo, the Red Earl of Ulster, inherited Galway Castle from his father, Walter de Burgo.

A sketch-map of Galway by Barnaby Gooche, dated to 1583, shows a two-storeyed, gabled and crenellated building with two ground-floor doors located in the general area of the present-day Custom House. The 1651 pictorial map of Galway shows a rectangular open-roofed church-type building with a base batter and/or buttresses on the site of the Custom House. The building is described as 'the old castle of the most illustrious Lord, Richard de Burgo, the Red Earl'.

Two test-trenches were excavated by machine in the areas of proposed ground disturbance. Trench 1 was located in the carpark on the line of the proposed underground duct, which is due to run towards the existing warehouse. Trench 2 was also located in the carpark and on the line of the west wall of the proposed new office block immediately outside the existing store and boiler-house; it was excavated first.

A 14.2m stretch of wall, 2.4m thick and over 1m high, was uncovered in Trench 2. The south-eastern end of the wall probably runs under the Custom House as far as Flood Street. The top of the remains of the wall were less than 0.3m below the present tarmac level. It was also evident that the wall had at least two skins. The outer was 1m thick while the inner was 1.4m thick. The core of the outer skin consisted of small, heavily mortared migmatite stones. Where evident, the wall faces and cores consisted of migmatite and red sandstone/granite stones, the type of stone usually found in medieval buildings and walls in Galway City. Generally speaking, limestone is the predominant building stone used in post-medieval buildings in Galway. A rough, heavily mortared rubble foundation projected 0.16m out from the base of the wall.

The entire western half of Trench 2 was taken up by part of the wall. Up to 0.8m of modern fill was excavated by machine in the eastern half of the trench outside the wall. Underlying the modern fill was a dark brown/black sticky clay (C2).

C2 and all the layers below it seem to be stratified and undisturbed. C2 was very organic and contained a large amount of sea shells, especially oyster. A large number of animal bones, charcoal, clay pipes, pieces of iron and slag, copper and post-medieval pottery were observed in it. Some of this material was recovered by hand, while most of the context is still in situ. The top of C2 tended to rise upwards from north-west to south-east in Trench 2.

A test-pit was hand-excavated through C2 and down to the natural subsoil outside the wall in the north-eastern corner of the trench. It measured 1.3m x 0.5m and was 0.52m deep from the bottom of C2 to the top of the orange natural gravel. Nine different stratified contexts were observed in the pit. The stratigraphical sequence from the top towards the bottom was as follows. Underlying C2 was a light brown sticky clay, 0.03m thick, which produced shell, brick, iron slag and some animal bone. Under this was a black clay, very rich in charcoal, 0.07m thick. Some light brown streaky lenses were evident through this layer. It produced iron slag, wood, iron, shell and some animal bone. Next came a black, charcoal-laden layer, 0.18m thick, which produced iron, iron slag, oyster shells, part of an animal skeleton, post-medieval(?) pottery and some animal bone. Underneath again was a grey brown sticky clay, 0.06m thick, which produced charcoal, iron slag and some animal bone. Large lumps of iron and iron slag were recovered abutting the wall face at the bottom of this layer. Below this was a sterile, sticky yellow clay, 0.04m thick. Under this was a thin black layer, 0.02m thick, which produced no small finds. Next was a dark brown peat, 0.07m thick, which produced some animal bone and burnt stones which resemble a type of stoneware pottery. Under this was a grey stony layer, 0.02m thick, which produced two sherds of French Saintonge pottery. This overlay a sticky brown clay, 0.04m thick, under which was a natural sticky orange gravel, 0.1m thick, overlying a natural brown dry clay and gravel layer, 0.09m thick.

Trench 1, which was 2m wide, ran in a westerly direction for a distance of 7.5m from the western edge of Trench 2. The eastern end of the trench exposed the inner edge of a wall and a possible entrance. The top of the wall remains at the eastern end of the trench were only 0.1m below the tarmac in the carpark. Up to 0.6m of modern fill was excavated by machine down to a brown dauby clay layer, 0.2m thick. The two modern service pipes which cut across Trench 1 also cut through this modern fill layer in Trench 2.

A second test-pit was hand-excavated through the clay layer at the western end of Trench 2. The layer produced an abundance of oyster shells, iron slag, large pieces of iron, some animal bones and a possible sherd of crude pottery. Underlying it was a black, dauby, charcoal-rich clay, 0.16m thick, which produced blackened and burnt animal bones and shells. Underlying this was a brown dauby clay, 0.15m thick, which produced a fragment of a copper/bronze plaque and some animal bone and shell. It lay directly on top of a layer of large cobbles, some of which were up to 0.35m in size. Initially it appeared that the cobbles may have represented a floor level within the 13th-century castle and therefore no further excavation took place. However, having lifted one cobble, a further layer of midden material was present beneath it. The depth of stratigraphy beneath these cobbles is still unknown.

It would appear that substantial and important remains of the 13th-century de Burgo castle have been uncovered. The proposed extension to the Custom House and associated developments will affect the archaeological structures and the rich stratified archaeological layers which are now known to exist on site. It was recommended that all areas should be archaeologically excavated, recorded and resolved before any construction work commenced on site (see Excavations 1997, No. 199).

Rathbawn Road, Castlebar, Co. Mayo