1996:089 - DUBLIN: Fishamble Street/Essex Street West, Dublin

Archaeological monitoring of construction works, and particularly of subsurface works, on a development site bounded by Fishamble Street, Essex Street West and Exchange Street Lower was carried out between 16 April and 14 June 1996. The site lies between the Viking (early twelfth-century) and Anglo-Norman (thirteenth-century) city walls, east of the supposed location of an inlet at the bottom of Fishamble Street known as the 'Fyschhe Slippe'.

Assessment work carried out in 1989 revealed a two-phase sequence of reclamation of the river front from the late twelfth century through to the thirteenth or early fourteenth century, after which time the area seems to have remained open and cultivated inside the Anglo-Norman city wall. The site was investigated by Margaret Gowen in March 1995 by the excavation of a series of mechanically opened slit-trenches (Excavations 1995, 19). Results of the investigations indicated a build-up of deposits similar to those recorded on an adjacent site at SS Michael and John's, excavated in 1994 by Linzi Simpson (Excavations 1994, 23–4).

The main aims of the archaeological monitoring were to observe the piling process in progress; to retrieve artefacts from the archaeological material; to describe and evaluate the resulting impact of the piling process on the artefects, structures and stratigraphy encountered; and to monitor the laying of all ground beams and services.

The piling process involved the casting in situ of 41 piles, of which 28 were 900mm in diameter and 13 were 600mm in diameter. A 1m-long corkscrew-shaped drill was bored 3m into the ground. A concrete casing, between 6m and 8m long, was then inserted into the 3m core and pushed down until it met bedrock (5m and 5.7m below present ground level on the site). The augur was inserted into the casing and removed all material down to bedrock.

A reinforced steel cage was inserted into the casing and the pile filled to the top with poured concrete. The concrete casing was then removed. The material extracted from the augur was examined for maximum retrieval of artefacts. Two steel-wire frames, 2m by 1 m in size and with a 20mm2 wire mesh, were set up off ground level and used to sieve material. Owing to the compact nature of the archaeological deposits, the material was broken up with spades before trowelling and sieving began. Each pile was numbered, and artefacts relating to a particular pile were accorded that feature number.

The testing carried out in 1989 had previously identified three revetment structures, two with associated clay banks, and a light timber feature which crossed the site from east to west. Nine piles yielded wooden remains which averaged 0.22m in width by 0.38m in length. However, the method of extracting the material by augur caused extensive 'shredding' and breakages, making identification almost impossible. No cuts or markings were identified on the timbers.

Three oak planks retrieved from pile 15 were identified as part of a revetment structure. One of the timbers appeared to be part of an upright; one end had a two-shouldered tenon with a horizontal dowel, the other end was broken and partly shredded. In addition, several long, narrow timber pieces, 0.4m long and 600mm wide, with broken ends were retrieved from the pile. Similar long, narrow strips of wood were retrieved from pile 16; these appeared to be barrel-staves or parts of planking. Concrete seepage at a lower level of pile 25 resulted in the excavation of a small trench to locate the top of the pile, and a large squared oak timber, 1.3m long and 0.08m wide, was retrieved from the trench. One end of the timber had a one-shouldered tenon with two horizontal dowels. The timber extended east-west and formed part of a revetment structure, a portion of which was still in situ within the west-facing section of the trench. This part of the revetment consisted of a squared upright timber, 0.4m long by 0.08m wide, flush with the upright. The revetment structure was located in a 05m-thick band of grey sod-like material which contained a lot of shell but produced no finds.

All material was removed by the piling augur, and each insertion removed approximately 1–2.5m of archaeological deposits. Some subsidence and water ingress occurred in some of the cored piles which affected the composition of the archaeological stratigraphy. However, once the initial 0.8m of overburden was augured it was possible to identify uncontaminated archaeological deposits. The stratigraphy appeared to be uniform across the entire site and consisted mainly of basement fill, loose rubble followed by brown/black organics which revealed the artefacts. These deposits overlay grey silts which occasionally yielded low-grade artefacts.

Archaeological testing in 1989 revealed a clay bank 4m wide extending east-west across the site, lying approximately 8m south of the Exchange Street Lower street frontage. The bank extended beyond SS Michael and John's church, where it was composed of orange gravel over a grey sandy clay, which in turn overlay a yellow clay.

The deepest trench cut for the laying of ground beams was 1.6m below the finished floor level of 3.45m. This depth was well above the archaeological levels, which occur 2.5m below present ground level.

In conclusion, all of the artefacts retrieved were in a similar condition to those retrieved under ordinary excavation procedure. The pottery sherds, bone objects and leather did not display any breaks or tears due to the piling process. As the archaeological deposits were removed directly from the augur onto the sieves, maximum retrieval of artefacts was accomplished on site.

Rath House, Ferndale Rd. Rathmichael, Co. Dublin