2002:0441 - DUNNYNEILL ISLANDS, Down

The Dunnyneill Islands lie in Strangford Lough, 2.5km to the north-east of Killyleagh. They consist of a larger and a smaller island linked by a causeway at low tide, which, uniquely of all the islands in Strangford Lough, are strategically situated so as to command both the narrows at the mouth of the lough and the entrance to the Quoile Estuary. A narrow gravel bar, barely visible at high tide, lies c. 200m to the east of the islands. The main island is formed of a small drumlin with a boulder-clay core. It is roughly D-shaped, c. 100m in maximum extent, and rises to c. 16m above sea level. The southern side of the island is defined by a steep and actively eroding cliff that faces the mouth of the lough.

The highest point of the island is a plateau surrounded by a counter-scarped bank, ditch and inner bank, enclosing an area c. 30m in diameter. The southern half of this enclosure has been lost through erosion; however, the extant lengths of bank and ditch suggest that it either originally had an irregular layout or represents a smaller subcircular enclosure with at least one addition. The surviving part of the enclosure is not continuous; it is uncertain whether this is due to it never having been completed or to later destruction. An original entrance appears to be present on the northern side. In addition to the main enclosure around the top of the island, a low earthwork, now interrupted and disturbed by a series of hollows marking later activity, apparently enclosed the base of the hill just above the high-tide line.

In addition to a detailed topographic survey of the island, limited excavation of the main enclosure was undertaken over two weeks during September and October 2002, with the aims of ascertaining the character of the site and quantifying the rate of its destruction through coastal erosion. Two trenches were opened, one across an open area of the interior (Trench 1) and another across the enclosing banks and ditch (Trench 2).

Trench 1 measured 5m by 4m, with its longer axis aligned north-east/south-west. Underneath the topsoil was a short sequence of superficial deposits that included a localised spread of angular stones that may represent either collapsed or slighted bank material. These overlay several truncated features cut into, or overlying, a dark brown, silty clay loam that probably represents an occupation deposit. These features included: in the southern corner of the trench, an area of burnt clay interpreted as the base of a hearth; adjacent to the south-western edge of the trench, a single post-hole with stone packing; and two superimposed linear features running roughly adjacent to the north-western edge of the trench on approximately the same east–west alignment. The earlier of these two linear features was a shallow gully, c. 0.1m deep and c. 0.7m wide, which was cut by a slightly curved, slab-lined cut, c. 0.3m wide and c. 0.15m deep. The function of the two linear features is uncertain; they may be related to drainage or form the footings for a palisade or wall. At the eastern end of the trench the earlier of the two linear features cut through a spread of stones in the dark brown, silty clay loam occupation deposit, which may represent a second spread of either collapsed or slighted bank material. Underlying the probable occupation deposit was a single, truncated post- or stake-hole in the southern corner of the site, which was cut into a partially excavated clay loam that probably represents an ancient topsoil and that overlay the natural boulder clay.

Trench 2 was 1.5m wide and laid out on an approximately north–south axis across the inner bank, ditch and outer bank. The southern end of the trench extended slightly into the interior of the enclosure, and the northern end terminated on top of the counter-scarp bank. The excavation results were consistent with the inner bank, outer bank and ditch being constructed as a single event, but this was not stratigraphically proved. The ditch has a U-shaped profile and is 2.6m wide. During excavation of the ditch a series of secondary silty clay loam fills defined by tip lines, which overlies a loamy primary fill, was recognised. The top of the inner bank survives to 2m high above the base of the ditch, and the outer bank is 1.25m above the base of the ditch. The inner bank had been greatly denuded, as a result of either collapse or deliberate destruction. Only its rubble core survived intact, and no evidence of faced courses or timber features such as a palisade was recovered. The rubble core overlies and preserves a series of occupation deposits that in turn overlie the natural boulder clay. The outer bank was not excavated but has an estimated width of 3m and survives to 0.5m high.

A large quantity of animal bones and a small, but diverse, range of finds were recovered during the excavation. Provisional analysis of the artefacts suggests evidence of an early medieval and at least one prehistoric phase of activity. The early medieval phase is represented by three sherds of Thomas’s Class E ware. Given the island’s strategic position within Strangford Lough, it is not surprising that excavation has revealed evidence of multi-period activity, and it is probable that full analysis of the artefactual assemblage will yield evidence of additional phases of activity. Unfortunately, most of the finds were recovered from stratigraphically late or disturbed contexts, and, until a programme of radiocarbon dating has been completed, the date of the enclosure and of the other features recorded during the excavations will remain uncertain.

Belfast BT7 1NN