2013:057 - Seagrange Road, Baldoyle, Dublin

The object of the excavations was to investigate what remained beneath Seagrange of DU015-018, a probable medieval moated site. This site was identified as a crop mark from a Cambridge Series aerial photograph taken in 1970, pre-dating the construction of the housing estate by 3 years. To this end 5 separate cuttings were undertaken, 3 of which (Trenches 1, 2 and 3) were opened in residential gardens and 2 (4 and 5) on Council green space within the estate. These trenches yielded mixed results as was expected given the scale of development carried out over the site in the 1970s.

Two main phases of activity were identified, medieval and post-medieval. A scattering of worked lithic implements also suggests that the area was frequented during the prehistoric period, notably the Late Mesolithic and Early Neolithic.

Trench 1 was 1m wide and 2m long and contained a shallow layer of topsoil mixed through with small amounts of construction debris. Beneath this layer, a layer of ploughsoil was encountered which contained 2 sherds of 12^th-13^th-century ceramic as well as ceramic of an 18^th- to 20^th-century range. This ploughsoil came down onto yellow boulder clay. The merest edge of a feature occurring in this trench informed the positioning of Trench 2 which was opened 0.5m to the south.

Trench 2, 2m wide and 2m long, contained a wealth of artefactual material retrieved from the ploughsoil. This material included 2 sherds of 12^th–14^th-century ceramic, several fragments of glass which has been provisionally attributed to the early modern period but which could be earlier (chemical analysis ongoing) and several chipped flint pieces several of which constitute formal tool types dated to the Late Mesolithic and Early Neolithic periods. Below this ploughsoil the feature identified in Trench 1 continued into Trench 2 where it was easily identifiable as a shallow linear gully (0.6m wide x 0.16m deep with an excavated length of 2.3m). This gully was backfilled with kitchen midden material. The upper fill was a dark brown loose silty clay containing an abundance of complete, at times articulated, cockle shells with occasional fragments of mussel shell and oyster shell also in evidence. Several cow and horse bones were also present in this context as well as a moderate occurrence of charcoal flecks. Floatation of a sample of this context has revealed charred barley and oat grain. A finely worked bone point which may be associated with textile production and a small fragment of iron bloom were also recovered from this context. In addition, 2 worked flint pieces, one a blade fragment, were retrieved. This fragment lay immediately below a juvenile horse mandible.

A shallow basal fill representing initial silting-up of the gully lay at the bottom of the feature. This clayey silt contained some cockle shell but also some large cattle bone and caprovine bone. Both carbonised oat and barley grain were recovered from this context.

The gully cut a very shallow, flat-bottomed pit with an upper fill similar in composition to the upper gully fill.  However it was harder, more compact, there were less cockles retrieved and smaller animal bones represented cattle, pig and caprovine. This context overlay a layer of small stones resembling metaling below which was a floor of gravel-rich clay baked to the consistency of poorly fired ceramic which had a depth of 30mm and was surrounded by orange oxidised subsoil. Only a portion of this feature was uncovered but, based on the curved outline of the exposed area, its full shape in plan might be circular. This feature shares several characteristics with that of a medieval glass furnace. Results from AMS dating which is currently being carried out on samples of animal bone from the gully should inform final interpretation of this feature.

Trench 3 was 1.5m wide and 8m long and was opened 10m to the north of Trench 1. Beneath topsoil mixed through with modern material, was a redeposited layer of subsoil which contained modern debris. None of the ploughsoil encountered in Trenches 1 and 2 was observed. The ground was crossed by 2 modern service ditches. A leaf-shaped arrowhead indicating Early Neolithic activity was recovered from disturbed subsoil and 2 fragments of Dublin-type ware were recovered from the backfilled topsoil within one of the service ditches.

Trench 4 was 1.5 wide and 8m long was opened on Council green space and uncovered very heavily disturbed ground overlain with disturbed topsoil. The disturbed subsoil was tested to a depth of 1.25m and, at this depth, there was no sign of the disturbance abating. This substantial disturbance is connected to road construction. The topsoil which was laid over this disturbance contained some further fragments of probable early modern glass.

Trench 5 was 0.5m wide and 8.5m long and was opened during the final days of the excavation. This trench gave a clear indication of where the disturbed ground in Trench 4 ended. An 18^th-20^th-century field boundary was identified but was not bottomed due to time and resource constraints. A selection of late 18^th-20^th-century ceramic was recovered from both the disturbed topsoil in this trench and from the field boundary.

Although the enclosing element of the suspected Moated Site DU015-018 was not located, the presence of medieval artefacts and features beneath the garden soil of the suburban houses bolsters the interpretation of this as a possible enclosure. Moated sites within County Dublin are rare and no examples have as yet been excavated. This highlights the significance of the Seagrange monument and the necessity to fully investigate this monument over future seasons. The full significance of this site has, however, yet to be assessed and is contingent upon the results from the AMS dating and the chemical analysis of the glass fragments uncovered. If the possible glass furnace described above can be dated to the medieval period and the glass fragments are of a composition consistent with that period, this site might provide the first evidence for glass production from that period. Although this is currently far from certain, the Seagrange site is nonetheless of potentially national significance. The community aspect of this excavation, which has attracted both local and national media coverage, is also of note.