1997:105 - DUBLIN: Back Lane/Lamb Alley, Dublin

A pre-development excavation commenced at the site in mid-October 1996 and continued until mid-March 1997. The excavated area consisted of a 6m-wide trench running east-west for approximately 32m between Back Lane and Lamb Alley. The archaeological deposits were sealed by an average of 0.4m of overburden with only minor cellar disturbance. The entire excavation area was excavated to subsoil. Seven phases of activity were recorded.

Phase I-postholes, pits, gullies, and a clay bank
The earliest feature recorded was a series of ten postholes in the east of the site. They appeared to be set on four roughly parallel lines, 2.5m wide, running north-south, and may represent the remains of a substantial palisade. Two of the posts on the outer lines were cut at an angle and could have acted as buttresses for the main structure. There were no finds or material suitable for radiocarbon dating from any of the postholes so it was not possible to date the feature accurately, but it may represent an early defence of the Viking town.

In the west of the site a bank of redeposited clays, standing over 2m high, sloped eastwards into the excavated area. There was a lot of later disturbance to the upper layers so the original height is unclear. A decorated bone comb (Dunlevy's F2 class) was found in a thin organic deposit at the base of the bank, giving a date of the late 9th century.

A number of pits and gullies that were associated with this level were recorded in the eastern area of the excavation.

Phase II-cultivation
A cultivation soil containing numerous shell fragments was recorded extending from the clay bank in the west across the entire excavated area. This phase is associated with the Hiberno-Norse period, with pottery from the upper levels dating from the mid-12th century.

Phase III-expansion of the clay bank
A second deposit of clays was added to the existing Hiberno-Norse bank in the west of the site. These sealed the western extent of the cultivation soil found in the previous phase. A metalled surface extended eastwards from the bank. This activity is dated to the late 12th century and the clays represent a consolidation of the earlier bank by the Anglo-Normans.

Phase IV-post-and-wattle structures
This phase was characterised by the development of property boundaries delineated by post-and-wattle fences with post-and-wattle structures constructed within them. The full width of one plot (5.5m) was evident within the excavated area, with the extreme north and the extreme south of two other plots also being recorded. A total of six post-and-wattle structures were recorded in the eastern half of the excavated area. Only one of these lay wholly inside the excavated area and only the two structures partly exposed in the extreme east of the cutting could be positively identified as 'houses'.

The excavated remains of the earliest 'house' had a maximum length of 3.1m east-west and 3.2m north-south. A doorway 0.8m wide in the west wall was defined by a pair of squared oak door-jambs. Both jambs had rebates to hold the wattle fence. Assuming that the doorway was centrally placed, the structure would have been 4m wide. An east-west line of posts in the southern half of the structure was all that remained of an internal aisle. A series of ash spreads to the east of the doorway represented rake-out material from the hearth rather than in situ burning. The structure would have fronted onto Back Lane.

The second 'house' directly overlay the first. The entire west wall of the structure was exposed and had a total length of 4.7m. A doorway, 1m wide, was marked by two postholes. It was slightly off-centre, being nearer the northern side of the structure. The walls survived to a height of 0.15m. This house would also have fronted onto Back Lane.

The most complete structure recorded lay to the west of the two houses and took the form of a rectangular hut with no central roof supports and no hearth. It measured 5.6m east-west and 3m north-south. A threshold was placed in the north wall but its western side had been removed by a later pit so its full width is unknown. A squared oak post represented the eastern door-jamb. The north wall had been further damaged by a later drain and only survived to a height of 0.1m, whereas the remaining walls survived to a height of 0.5m. The roof was probably supported by the wattle walls, the door-jambs and two further posts set into the south wall. The structure probably functioned as a workshop, possibly for carpentry owing to the large amount of wood-chips and barrel-stave fragments in the deposits both inside the structure and outside the doorway.

The other structures recorded were represented by very fragmentary remains to the west of the hut structure and two structures in the south of the excavation, but most of the remains lay outside the excavated area. The latter structures lay in the southern property plot while all the others were within the main plot. No structural remains were recorded from the northern property plot.

A series of pathways and cesspits were recorded associated with the post-and-wattle structures.

Pottery remains have dated this phase to the late 12th/early 13th century.

Phase V-stave-built structures
Overlying the post-and-wattle structures in the east of the excavated area was a large stave-built structure, probably a house. It would have had a maximum length of 12.6m if it extended as far as the present Back Lane street front and was 4.5m wide. The excavated remains, however had a maximum length of 9.8m. The walls of the structure were constructed by placing large, mortised oak base-plates horizontally on the ground. Large, squared oak posts were then set into the base-plates and thin oak planks were attached to the outside of the posts in a clinker-built fashion to form the walls. The posts, as well as supporting the plank walls, would have acted as roof supports.

The excavated remains show the structure to have been divided internally into three separate areas-a main room, a back room, and a side passage. The main room spanned the full width of the structure-4.5m-and had a maximum excavated length of 6m. A hearth was recorded roughly centrally placed in the room. There were no kerbstones located around the hearth bowl and it was not lined. A wooden drain ran along the inside of the north wall of the room.

The back room was to the west of the main room and was separated from it by an internal plank wall. The room measured 3.55m east-west and 3.15m north-south. A possible entrance can be inferred from two mortises recorded in the base-plate of its north wall (which separated it from the side passage). These were set 0.9m apart and may have originally held door-jambs. There was also no planking in this section of the wall.

The side passage ran between the north wall of the structure and the back room. It was 3.8m long and 1.2m wide and provided access to the rear of the structure. A pathway extending from the rear of the structure to a cesspit was later replaced by a second pathway to a subsequent cesspit-presumably because the first one was full!

In the west of the site, a large sunken structure was recorded cut into the earlier bank deposits. The first stage of the construction involved the excavation of a large pit through the clay bank. The pit measured 8.3m east-west and would have been 8–9m north-south, although this lay outside the excavated area. The walls of three sides of the structure were then erected inside the pit, approximately 1m from the edges. On the eastern side, the cut itself served as the wall of the structure. The walls were again constructed of large, mortised, oak base-plates with plank walling, which only survived on the western wall of the structure, however. When the walls were constructed the pit was backfilled with the excavated clays on the outside of the walls. The roof would have been supported by the wall posts, but the structure also contained three central internal roof supports which would have rested on stone post-pads. Only one of the posts survived in situ.

The entrance to the structure was at its north-east corner and consisted of a passageway 2.3m long and 1.4m wide outside the main structure. Two threshold beams were recorded, one at either end of the passage, the first representing the entrance to the passage and the second being the entrance to the structure itself.

There was evidence of repair to the north wall, with three additional posts being inserted sometime after the initial construction. These posts were not set into the baseplate but sat directly on it.

Following the levelling and backfilling of the sunken structure, two very fine timber-lined pits were recorded in the west of the excavation. They measured 2.4m by 2m by 1.7m deep, and 2m by 1.8m by 1.7m deep. Their original function is unclear, but the larger pit was finally used as a cesspit.

The features in this phase are 13th-century.

Phase VI-later medieval activity
This phase marked the end of the use of timber in the construction of houses. All of the earlier features were sealed by a 0.5m-deep deposit of clay across the site. This helped to provide a firm foundation for the subsequent structures, which were built of stone. The archaeological remains in this phase are poor owing to a high level of post-medieval disturbance. For this reason it is difficult to get a clear picture of the nature of the activity, but there is evidence that it may have been more industrial than habitational. This is suggested by large ash and burning spreads and some associated deposits with a slag content.

There are historical references to stone houses on Rochelle Street (Back Lane) in 1260, so the beginning of this phase of activity can probably be dated to the mid- to late 13th century.

Phase VII-post-medieval activity
A number of drains, pits, barrels, cisterns, pathways, cellars and wall foundations dating from the post-medieval period were also recorded during the excavation.

Rath House, Ferndale Road, Rathmichael, Co. Dublin