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Architecture Notes

Event ID 841556

Category Descriptive Accounts

Type Architecture Notes

Permalink http://canmore.org.uk/event/841556

Excavation of the Old Scatness settlement (NMRS HU 31 SE 21) commenced in 1995 as part of the Old Scatness/Jarlshof Environs Project (see DES 2000, 79-81).

The broch tower

Removal of the northern baulk of material between the Old Scatness site and the airport access road was necessary for safety reasons, but also provided the opportunity to investigate the unexcavated northern portion of the broch wall and any accompanying structures. This work revealed the full extent of the damage to the northern part of the site, due to the construction of the access road in the 1970s. It is now apparent that all archaeological structures N of the broch wall were removed in the road construction, and that disturbance extends in places down to the basal quartz sands.

A short section of the northern circuit of the broch wall was excavated down to its foundations. The foundations sealed c 20cm of earlier deposits, below which was natural quartz sand.

The tertiary building phase identified within the shell of the broch (Structure 7) is represented by a cellular structure with five peripheral 'lobes' formed by cells. These five cells, each with a single-faced curved wall backed onto the rubble infill of the broch, bound a central area, the junctions of the walls forming triangular piers between the cells. A double kerbed hearth dominates the central area, and to the E is a passage with stairs up to the broch wall. Evidence from the walling and rubble infill of this building strongly suggests that it may have been corbelled.

Structures W of the broch

Excavation of Structure 12, to the W of the broch, also continued. This circular building has an internal diameter of 9.7m and an average wall thickness of 0.95m. Once the building had gone out of use it was used as a depository for ash and midden, with a layer of rubble (not collapse) sealed between the dumps of ash. Beneath this debris was a secondary floor surface, with paving in the cells between the long drystone piers, and a central flagstone hearth with kerbing open to the W. At the present time the walls stand to a maximum height of 2m. Analysis of the long piers on the S side of the building showed that they had originally been aisled piers 1.2m in length, terminating in orthostats on their inner and outer faces and similar to the piers in the aisled roundhouse at Jarlshof. These piers were later extended to butt the inner wall of the structure. The N wall of Structure 12 appears to be original and shows clear signs of corbelling approximately 1.4m above the secondary floor surface. Occupation of the structure evidently ceased when part of the N wall collapsed, knocking over several piers, cracking the long orthostats and burying the floor in rubble.

Excavation continued in Structure 14, a roundhouse to the S of Structure 12 which shares a wall with the latter building. Like Structure 12, this building has a maximum diameter of 9.7m and has several later occupation layers, but Structure 14 is oval in shape. Two types of piers, long piers over 2m in length and short aisled piers over 1m in length, are present in this building. There are clear signs of modification and reconstruction; two of the long piers which butt the N wall obscure cupboards or aumbries in that wall. The surviving height of the piers, level with a scarcement ledge built into the highest surviving N section of wall, suggest either an upper floor or a floored gallery over the piers. A second, later floor surface was excavated below the one identified last season; this too had an informal hearth consisting of a compacted surface of small pebbles, with paving in the cells formed by the piers. A rubble feature running from the hearth to the SE of the building proved to be an irregular pit cut into this secondary floor surface which had been filled with a large quantity of animal bone and rubble.

Structures E of the broch

Excavation continued in Structure 11, a wheelhouse to the SE of the broch, containing seven triangular piers, which appear to have been inserted into a larger and earlier building. The primary flagged floor of Structure 11 was excavated, and proved to contain a central rectangular hearth surrounded by a horseshoe-shaped kerb. This is similar to the distinctive hearth form in Structure 7, suggesting a degree of contemporaneity. Orthostatic settings separated the central zone of this building from four of the cells. A NW doorway leads into a small circular cell, Structure 20, by means of a step behind a short screening wall, forming an 'inner sanctum' to Structure 11. This doorway was later blocked. The triangular piers are secondary, butting the inner wall of the structure and partly sealing the primary flagged floor. Footings for a thin rectangular pier suggest the building originally had a different form.

Structure 21 is a large piered sub-oval building on the eastern flank of the mound. Excavation of the ash fill of this building recovered many fragments of bivalve moulds for pins and penannular brooches. The W wall of this structure butts the broch wall, whilst the E wall is contained by the ditch rampart revetment. The structure has rectangular piers like those in Structures 12 and 14, and like those buildings it has undergone a number of modifications. There is a secondary wall division which runs diagonally across the building, with a still later wall built parallel to it to form a late corridor. To the NE a series of later walls further divided the space into small cells. One unusual feature of this building was a very large flagstone which sloped into the ground at an angle of 45o between two piers, suggesting that the piers were supporting an upper floor or gallery.

Structure 5 was a multi-cellular semi-subterranean building characteristic of 'Pictish' architecture, inserted into the fill of Structure 21 and excavated in previous seasons. Removal of the northern baulk allowed access to features extending to the N and E from this building. These features proved to be a corridor, possibly an entrance passage, running E. It is possible that this passage also connects Structure 5 with Structure 7, inside the broch, though confirmation of this awaits further excavation.

Sponsors: HS, BP Exploration Operating Company, EC Special Transitional Programme, Scottish Natural Heritage, Shetland Amenity Trust, Shetland Enterprise Company, Shetland Islands Council Charitable Trust, University of Bradford.

S J Dockrill, V E Turner and J M Bond 2001

(HU 389 106) Excavation of the Old Scatness settlement commenced in 1995 as part of the Old Scatness/Jarlshof Environs Project (see DES 2001, 86).

The broch tower (HU 31 SE 21). Work continued on the excavation of the broch tower itself on the northern part of the circuit, where the construction of the airport access road in 1975 came close to the broch foundations. A second staircase was found, starting in a cell at what is possibly ground level, with an (unexcavated) passage to the interior of the broch. The stair rises clockwise from this passage, to the top of the standing portion of the walls.

Just to the W at the base of the outer broch wall, at the level of the old ground surface, a deposit of what appeared to be compacted peat was found. This peat was unusual in that it was lying in a hollow in the basal quartz sands, and the sides of the hollow appeared to have been artificially straightened. Initial post-excavation analysis has revealed degraded plant material and other remains, including hair, in this deposit. At present this feature is interpreted as a natural pool or spring which was artificially deepened or cleaned out in the Iron Age, during the occupation of the broch.

The quartz sands underlying the site had been assumed to be natural since coring around the site had shown them to be of some depth, with no anthropogenic input. However, excavation in the small area of exposed ditch deposits to the E of the site showed that a darker, more organic sand underlies the 'natural' sand in this area and, in the small area investigated, produced a number of struck quartz fragments. The date and nature of this feature is as yet unknown, but it is stratigraphically earlier than the broch foundations.

Structures W of the broch. Structure 12, the early roundhouse immediately W of the broch, was investigated further this year. The walls of this building stand to over 2m high in places, and provide evidence of the considerable remodelling the building underwent during its occupation, including the blocking of its original, monumental W-facing doorway and the construction of a simpler doorway to the SE. It is possible that the blocked door was later used as the base of a stair; wear and polish on the stones certainly suggest this. A series of hearths and floor layers were excavated from the centre of the building, and it gradually became apparent that the structure had consisted of raised stone-flagged platforms in the bays around the perimeter, with a sunken central floor level and hearth. The flagged platforms, which were partially hollow underneath, would have been both drier than the ground level and also warmer as hot air rose from the fire. To the N of both the original doorway and the later connecting door into another structure was a cell in which the flagging had collapsed; a pit had been deliberately dug under the floor level and then lined with drystone walling to support the flagged surface, whilst the pit itself had been filled with rubble and cattle bones. The series of floors around the succession of hearths in this building were highly compacted, composed mainly of ash with fragments of both burnt and unburnt peat. A scatter of pumice and serpentine fragments to the N of the hearth suggests an area of activity here. A surprising aspect of this building was that the series of flagstone hearths, surrounded by upright stones carefully bedded in a fine grey clay, were not central to the building but were offset to the SE, as the hearth in the adjoining building (Structure 14) was offset to the W. A whalebone weaving comb was found in the annexe to the E.

The pattern of raised flagged floors in the perimeter cells is one which is also being recognised in other buildings on the site, including the adjoining Structure 14. In this building, a series of informal hearths and ash layers seem to have built up over the central hearth, forming a mound of ash over a more formal flagged hearth surrounded by cobble stones. The top few layers of ash were interleaved with layers of small pebbles. It was at first assumed that these pebbles formed some type of radiant heating layer within the hearth, but not all the pebbles seem to be heat-cracked or scorched, and it is possible that they formed part of some act of sealing when the hearth went out of use. Structure 14 is a building with a complicated history; there seem to be several phases of rebuilding of the walls, with its current ovoid shape perhaps being the result of this. A cell constructed in the rebuilt SE portion of the wall seems to have been blocked in a later phase.

Structures E of the broch. Structure 11, the later wheelhouse to the SE of the broch with late inserted triangular piers, was further investigated this year to sample the earlier phases of the building. Like the earlier buildings to the W, it seems that this structure had raised dais-like platforms in the perimeter cells, surrounding a central pit-hearth substantially different in form to the earlier hearths. In the course of excavation, a flat stone removed from the late occupation surface proved to have a Pictish-style carving on its lower side. The slab of local sandstone has been carefully dressed around the sides; the top of the slab has been broken in antiquity. The carving is of very fine quality, and depicts a bear facing to the right. The stone is awaiting conservation, as the surface is flaking and fragile, and the top of the back has been lost in the break, but the startlingly life-like line of the body and the stylised joint spirals are clearly visible, as are the animal's claws.

Excavation also continued in Structure 21, a large piered sub-oval building on the eastern flank of the mound. The structure had been modified to a great extent in the past, with a wall built across the centre and a small room constructed within the SW part. Inside this room was what appears to have been a corn drier, built in the form of a small semi-subterranean corbelled cell. The floor of the drier contained large quantities of charred cereals and fragments of what appeared to be burnt peat. The room itself had a closely fitted flagged floor, which was heavily cracked, and the S wall contained two small aumbries or cupboards. The only door seems to have been a small irregular affair to the NE, perhaps designed to limit the through flow of air in the room.

Structure 7, the later Iron Age multi-cellular building constructed within the broch walls, was further investigated this year, the removal of material from the N baulk allowing the excavation of a flanking cell matching the one to the S. This cell proved to have a bench or platform at its W end, and contained the top slab of a schist rotary quern as well as a circular dressed slab of sandstone, perhaps a bakestone.

Post-medieval structures. The continued removal of material along the N baulk of the site revealed part of a crofthouse shown on the OS 1st edition 1:2500 map of 1880. The house was found to be of mid-19th-century construction, with a gable end fireplace. It had a beaten earth floor with flagging adjacent to the hearth. Secondary features included an internal wall, a kerb to the hearth and the blocking of the original entrance. Finds from the interior of the house include a quantity of sherds from stoneware flagons and iron objects. The house sealed a post-medieval soil that overlay prehistoric middens and structures.

Report to be deposited in Shetland Museum and the NMRS.

Sponsors: HS, BP Operating Company, EC Special Transitional Programme, SNH, Shetland Amenity Trust, Shetland Enterprise Company, Shetland Islands Council Charitable Trust, University of Bradford.

S J Dockrill, V E Turner and J M Bond 2002

People and Organisations

References