2000:0316 - LAMBAY ISLAND, Dublin

Excavation continued at this site in 2000 (results of the last four seasons are summarised in Excavations 1996, 36–7; Excavations 1997, 57–9; Excavations 1998, 62–5; Excavations 1999, 88). In brief the site shows evidence for two related activities: the working of the porphyritic andesite (porphyry) outcrops, which form the sides of the valleys for stone axe production, and the occurrence of a number of related features on the floor of the larger, eastern valley. These are under and partially truncated by a cultivation soil, which was the result of intensive 19th-century spade cultivation.

Excavation in 2000 focused on what was initially interpreted as a Neolithic occupation surface (C408/C904) at the southern end of an area 20m x 20m in the eastern valley. In an area of 9m x 6m this context was shown to have a considerable surface expression, with a very high density of finds dating to the Neolithic, made from a range of materials. While the overall make-up of the surface was dominated by angular pieces of porphyry debitage with a maximum dimension of 0.1–0.2m, there are a number of zones evident. It would appear that all of this range of material forming the surface of C904 was deliberately placed. It constitutes a deliberately created low monument with a number of distinct internal zones, both on the surface and in the stratigraphic sequence. Discrete earlier features were incorporated into this monument. A brief description of the general stratigraphic sequence is followed by a discussion of the excavation of different zones.

The modern cultivation soil lies above and cuts into the top of C904, which is 0.1–0.25m in depth and is the sediment in which the upper stones of the low monument were placed. Below this is C912, 0.05–0.12m in depth, characterised by the occurrence of inclusions of very small pebbles giving it a gravelly texture on the surface. This overlies C908, taken to be the original soil surface. Hence C904 and C912 appear to be the major sediments composing the matrix in which the stones and other material that make up the low monument are set. The origin of the sediments is not clear but, given the wealth and density of stone and pottery finds, it seems a strong possibility that they incorporate a range of deposits of other materials that have been chemically and biologically broken down since the Neolithic. It is also clear that there were localised foci of activity in the build-up of the monument. This has created a more complex stratigraphic sequence in some areas. Hence there are sediments sealed by C904 and, at a lower level, sediments sealed by C912. The continuity of these foci through a number of different depositional events suggests again that the monument was a deliberate, structured feature.

The north-west zone of the monument
This is an area 2.75m east–west x 2m, lying to the north of a number of large blocks of porphyry. The area is split into a larger western area and a 0.5m-wide eastern strip by a north–south cultivation furrow. The most distinctive part of the surface was a zone of beach pebbles about 1m wide (north–south) and 3.2m in length. There is a concentration of finds in this zone. On the main surface of C904 just to the west of the furrow was a fragment of an Orcadian-type macehead. Excavation of the pebble zone and the porphyry of varying size that made up the rest of the material revealed that C904 here was made up of a number of depositional events. The most notable of these was a lower pebble zone trending north-west/south-east. At its southern end it underlay the upper pebble zone; to the north–west it extended about 1m north of the upper pebble zone. As part of this lower pebble zone there was a dense spread of flint (more that 100 waste flakes, utilised and retouched pieces), jasper pebbles and some hammerstones. This material looked like it had been thrown down and did not appear to represent a knapping episode but seemed to come from a different context or a number of contexts. There were other, smaller concentrations of material that appeared to be deliberately deposited.

This series of depositional episodes that made up C904 rested on the surface of C912. This gravelly sediment was placed to cover earlier features. The most significant of these appear to be associated with a sediment (C910) that extends over an area about 2.5m x 1m. This is a dark brown/yellow-brown loam/sandy loam with charcoal flecks. It seems possible that C910 is the fill of a large cut in C908 and that it is underlain by a further gravelly sediment (C920), which may have been an initial deposit/lining in this cut. Within C910 is a polygonal slab setting, 0.75m x 0.6m, whose sides are formed by porphyry slabs. Immediately east of the slab setting is the north–south cultivation furrow. In a narrow strip east of this furrow under C912 a major deposit of material was revealed, which appears to be related to the slab setting and C910. This can be regarded as a hoard consisting of a range of deliberately deposited objects. The most signficant object in this deposit was a complete, unfinished Orcadian macehead. Immediately north of this there was a group of axeheads, two of porphyry and one of sandstone. Also as part of this deposit were flint flakes, rounded shale pebbles and a number of jasper pebbles. One of these jasper pebbles was axelike in shape. There was a mudstone axehead a further 0.5m further north. It would seem that the slab setting became a focus for depositional activity as the monument was built up.

The large block zone
Immediately to the south of the north-west area is a concentration of large porphyry and andesite blocks, up to 0.6m in maximum dimension, with smaller angular blocks forming a rough ‘bank’ about 1m wide (north–south) by about 3m. The most important of these blocks was a large, central one (0.6m x 0.5m). Some of the other blocks appear to have been added only as part of the C904 build-up, but this block and others in its vicinity appear to have been placed very early in the depositional sequence.

The zone south of the large blocks
To the south of the blocks the surface of C904 was dominated by angular and sub-angular pieces of porphyry up to 0.15m in maximum dimension. Excavation of these small porphyry blocks showed that under them was a residual area of cobbling formed by beach pebbles, similar to the material north of the large blocks. Over an area extending about 2m to the south and south-west of the large blocks, removal of the C904 material revealed a compact mass of angular porphyry of varying size set in the C912 sediment. It would seem that the compact mass of stones in C912 and the stones set in C904 were the two major episodes in the construction of the monument here. However, to the south and south-east there was a more complex series of depositional events.

The gravel zone
The initial recognition of this area was based on the fact that the surface of the monument here was formed by beach gravel. This gravel zone covered an area 2.5m x 1.2m. Immediately to the south-east there was another large porphyry block, which seems to have chock stones beneath it and a dense surface of porphyry pieces over an area 0.75m x 0.6m to the west of its base, with a less regular area of porphyry pieces to the north of the block (F30).

In the gravel zone there appear to have been a number of episodes of deposition of gravel, porphyry pieces, sediment and cultural material. This also resulted in a changing outline of the feature over time. The earlier acts of deposition were focused on what seems to have been a hollow (0.2m in maximum extent) in the C908 surface immediately adjacent to the southern edge of the excavation area.

The setting of stones associated with the porphyry block to the south-east (F30) has C904 sediment around the stones, and the porphyry block was chocked up by this setting. When the setting was excavated it appeared to be sitting on the C908 surface. Directly under the setting was a small, irregular, shallow pit cut into C908. This pit had a distinctive fill dominated by beach pebbles, flint and porphyry chips. In the top of this fill there was a piece of a broken jasper pendant. It seems probable that F30 was deliberately placed to cover and mark this earlier activity.

The east and north-east zone
When this area of the monument was revealed initially, it seemed unpromising because of the combination of cultivation and rabbit disturbance. It was clear, however, that there was a distinct drop in the surface of C904 towards the north in the area north of the gravel zone and east of the large blocks mentioned above. In the north-east area of C904 a notable stone is an andesite block, 0.7m in length and 0.15m in width.

Removal of the top layer of C904 revealed a series of flat settings of stone, which appeared to represent a stratigraphic sequence and formed part of a dense mass of stones in C904 extending for over 6m north–south by 2m. The latest of these is F27, disturbed on its west side by a furrow cut and measuring 1.2m north–south by 0.8m. On the surface there was a concentration of flint, both struck pieces and small pebbles, and rounded pebbles. This overlay F28, roughly circular in form with a maximum diameter of about 1.7m. The surface consisted of roughly concentric settings of stone, which seemed to revolve around the long, thin andesite slab mentioned above. On this surface there was a concentration of material to the north-west of the large slab, including the butt end of a porphyry axe and a concentration of pottery sherds, as well as struck flint. In turn, F28 overlay a general spread of stones extending to the south.

The lowest level of stones of these features are set in the C912 sediment. It seems clear that F27 was a late feature in the sequence, as it sits over relatively stone-free C912, as does the top level of stones at the southern end of this spread. The general character of the stones in C912 resembled the upper levels, and there were similar concentrations of cultural material—flint, pottery (globular bowl) and beach pebbles being the most common. The lower level of F28 had a ‘ring-cairn’ appearance, with a concentration of stones to the west of the large andesite slab, a stone-free area and then a ring of edge stones. Excavation of these stones showed that there are concentrations of placed material, such as flint chips, immediately south of the large slab and pottery to the north of it. Beneath this there is a relatively stone-free C912 with the large andesite slab, the only element of F28 still in situ. It was obviously the first element of F28 that was put in place.

There was a general stone spread, F25 (just over 1m in maximum extent), north of F28 with cultural material (hammerstones, pottery and flint) incorporated into the matrix. This area was excavated prior to F28, as the surface appeared to overlie the surface of F28. At its northern edge this seemed to be linked to a narrow trench feature cut into subsoil and C908. The F25 trench is 0.12–0.2m in width and has a sandy fill. It runs for 2m to the north. At its northern end it ran under the southern extent of F11, a linear, low cairn of stones, extending 1.5m x 0.75m. F11 consisted of a mass of stone, sediment and artefactual material placed in and over a shallow, narrow slot (0.1m wide) dug into the subsoil and over the F25 trench. The F25 trench runs to within 0.5m of the slot, and the two dug features would appear to be linked.

In excavating the stone spread north of F28, when the stones set in C912 were removed there was a complex of pits underneath (F25A–D). Stratigraphically the largest of these pits, F25B (0.82m x 0.6m with a depth of 0.35m), cuts both the trench and another pit to the west, F25A (0.58m x 0.39m with a depth of 0.27m). In turn F25A cuts a pit to the north, F25C (0.5m x 0.5m with a depth of 0.25m). F25D lies just to the south-west of F25A–C. It has been damaged by burrow activity, but its approximate dimensions are 0.36m x 0.3m with a depth of 0.15m. The fills of these pits were generally fairly homogeneous sediments. Notable features are that F25B was stone-lined, with a concentration of porphyry debitage and stones, including a hammerstone at the base. At the top of the pit fill there were at least two deposits of pottery and hammerstones on the eastern side of the pit. Feature 25C contained a large slab of porphyry placed flat in the pit close to its base. There were deposits of pottery sherds in F25D. This is a feature shared with what appear to be three other small pits south of F25D (F34, F35, F36). Excavation in this area also revealed a stretch of trench running east–west for just over 1m west of the F25 pit area. This seems likely to be linked with the north–south trench cut by F25B.

The excavation will be completed in 2001.

Belfield, Dublin 4