Monument record 251 - STAC A'CHAISTEIL, LEWIS

NB24NW 5 2024 4540.

(NB 2024 4540) A small ruin, said to be the remains of a castle, with a considerable portion of the wall still standing.
The small headland, Stac a Chaisteil, on which it stands, is now almost inaccessable either by land or sea. The ruin is about 50' lower than the top of the adjacent cliff, with which it is connected by a narrow ridge, still lower by about 40', over which it is im- possible to pass.
Name Book 1850.

On Stac a Chasteil there is the much-reduced and overgrown remains of a galleried dun or semi-broch. It consists of a substantial stone wall measuring c.13.0m in length and c.4.5m in width, and pierced by a central entrance passage 1.1m in width, placed on the lip of a cliff across the eroded ridge joining the promontory to the mainland.
The W half of the wall has fallen into the sea, but the footings of the outer wall face and entrance-passage survive. The outer wall-face of the E half has a considerable batter, and reaches a maximum height of 1.8m at the SE corner.
The inner wall-face is vertical, 0.9m in height, and pierced by a lintelled entrance, 0.8m in width, which leads into the remains of a cell too ruinous to be properly examined.
Within the enclosed area, measuring c.13.0m N-S by 10.0m transversely, there are traces of other structures of which only one can be recognised as an oval corbelled chamber, about 3.3m E-W by 2.3, transversely, with a lintelled entrance in its N wall.
Surveyed at 1/10,000
Visited by OS (A A) 20 June 1969.

one promontory enclosure, Stac a' Chaisteal appears to be constructed using techniquest similar to that seen in complex Atlantic round houses, using flat slabs of stone to produce a blockhouse structure, apparently with an intra-mural space. While the structural similarities may be a result of no more than the use of the same biuilding materials, the final effect at Stac a'Chaisteal must have been monumental, visually similar to the large complex Atlantic round houses, presenting a large featureless surface punctuated only by a small entrance.
Burgess, 2000, 130

NB 2024 4540 The complex remains of a possible late prehistoric dun occupy a dramatic position atop a tall stack, once accessible via a narrow neck of land, now collapsed and eroding severely. There are at least seven structures in various degrees of preservation covering an area approximately 20m N-S by 15m. The main structure consists of a 4m wide drystone wall, running E-W across the landward edge of the summit for approximately 13m. The eastern corner is upstanding to approximately 1.5m and retains a clear right-angled corner. This is built on the very edge of the outcrop which forms the top of the stack, teetering above a near-vertical cliff face. The wall is divided roughly in two by an entrance passage measuring just over 1m in width. Little remains of the structure to the W of this entrance save turfed-over footings and large foundation stones. These footings extend to the very edge of the western side of the stack, again stopping abruptly at a 50m high vertical cliff face. A stone hammer was recovered eroding from the E side of the entrance passage.
The best-preserved eastern half of this wall actually forms a larger structure when viewed from the N. A gallery or passageway, runs through it E-W, although it is hard to discern the exact internal dimensions of this feature due to considerable collapse of masonry at the SW corner. Large lintel stones cover the roof of this passage, and an opening 1m wide and high in the NE corner may have formed an entrance.
There are the remains of many turfed-over footings across the remainder of the summit to the N of the main defensive wall. The best preserved of these is a sub-rectangular building with a curved end, oriented N-S and measuring approximately 6 x 4m. The walls of this building are obscured at its southern end by irregular wall footings and tumbled masonry, but it may once have been related to the larger defensive wall.
A corbelled circular shieling-like structure partly overlies the rectangular structure to the NE. This appears to be a more recent building, and presumably the other structures were robbed of stone for its construction. The corbelling of the roof has partially collapsed. It measures 0.5m in maximum height and roughly 2m in diameter.
A series of revetted terraces, on which are the faint remains of other structures, leads to the steep slopes at the back or N of the stack.
Barrowman 2004, 134

The archaeology described by Burgess above forms a linear and large dry-stone rectangular wall or blockhouse running along the southern extremities of the site. This is actually only one element of at least six structures existing on top of the stack. Many further turfed-over wall footings and revetments are apparent across a small ovoid area measuring c. 30m by 15m, essentially two-thirds of the summit. The remaining third is an outcrop of bedrock and runs along the western side of the summit, elevated from the archaeological structures by a couple of metres.
Structure A
On the seaward or northern face of the stack, the curvilinear, double skinned remains of a drystone wall abuts an outcrop of rock and then runs along the edge of a north facing cliff for c. 3m before terminating at the easy angled grassy slop of a natural terrace. The wall is c. 0.4m thick and is comprised of blocks of Lewisian gneiss which measure on average c. 200mm by 200mm.
A small but regular break of slop immediately uphill of structure A could originally have been a wall or revetment.
Structure B
Some distance above A, resting neatly upon another outcrop of rock, are the horseshoe-shaped foundations of another double skinned drysxtone wall enclosure. This has a slihgly more substantial character, measuring roughly 4m by 4m in plan, and the walls are 0.5m thick.
Structure C
Structure C is also horseshoe-shaped and measures 5.5m N-S and 4.5m E-W externally. This wall rests upon and covers the entirety of an outcrop of rock. The foundations of the structure have been constructed of much larger slabs of gneiss measuring up to 1m by 0.2-0.7m, with a wall thickness of c. 1m. These walls are more substantial than ones previously described and belong to a more substantial building.
Only one course of walling is visible along its length, but a wall end to the south-east of the structure reveals at least 3 courses. This wall end or termination has been stepped inward (possibly corbelled) and is neatly squared off. This construction technique may be the result of a later phase of building
The west wall continues further south than the east wwall and is squared off by two courses of blocks which give the impression of being one side of a doorway. The accompnaying jamb is missing, though possibly represented by structure K, a linear grassy mound running along the same alignment, 1m beyond the wall.
Structure D
To the north of structure C, and running along the west side of structure B is a linear hollow feature set into a natural fissure in the bedrock. This measures c. 1m wide, is oriented north-south and is flanked to the west by a 1.5m high rock outcrop and to the east by a lower outcrop which has been accentuated by the construction of a roughly built section of drystone walling. It creases an excellent natural passage and may have been used to access the site from the seaward side of the stack. The section of walling is right-angled with faces to the north and east, and pershes on the edge of the outcop. It is made up ot large gneiss slabs and measures 0.5 x 0.5m, height 0.7m.
Structure E
is a drystone 'beehive' corbelled cell, meausring c. 4m by 4m. It is constructed of a single skin of large gneiss slabs over 1m in length and, although the wall has large gaps throughout, is well-preserved to a height of 0.5m or four courses above present ground level. Over these four courses, the cell vaults sharply inward from an inside diameter of c. 3.6m to 1.4m.
The cell has to apertures. The first is on the west side and appears to be a well constructed by partially collapsed entrance standing 0.3m high and 0.6m wide. A passage leading to the entrance is created by the eastern wall end of structure C and another wall.
The second aperture is to the north of the cell, where a 0.5m wide by 0.4m high opening leads to a 1m long passage of gneiss orthostats. Judging by the tumble present, it also seems to have been roofed.
Structure F
Three separate, possibly related features. The first F(a) is two courses of drystone, double-skinned wall of large (c. 0.6 x 0.3 x 0.3m) rectangular blocks, partially turfed over, c. 0.8m wide, stretching 3m east-west on the south-west edge of the stack. The western end is eroding off the cliff.
Structure F(b) consists of similar blocks, including a 2m long slab, running parallel and 2m north of F(a). This could be the remains of another wall of the same original/related structure. An area to the north of theses may have been another structure, having F(b) as its southern wall, turning north parallel to structure G, before abutting the outcrop forming the summit of the stack.
Structure G
G(a) is a substantial wall and footing up to 4 courses high, 5.5m long and at least 0.9m thick, running to the south of and slightly out of alignment with F. The wall is drystone, of 1m x 0.5m rectangular blocks of well-dressed gneiss. It is assumed to be double-skinned, but only the outer face is visible. It is battered.
The western end of G(a) is eroding over the cliff.
The eastern end, G(b) may be the same as the foundations of a wall running north-south, parallel to H's west wall. G(b) runs approx. 5m, other dimensions are unclear due to vegetation cover, and uses blocks of the same size and character as G(a).
Structure H
is the most substantial, upstanding building on the stak, up to 8 courses or 2m high. It is sub-rectangular, 6 x 4m. A substantial batter is visible on the south, landward facing wall. The building blocks the neck of the stack. The southern and western sections are collapsing and eroding, but the eastern wall and southeastern corner are well preserved on top of a 40m sheer cliff.
The north wall is intact to 1.5m without batter and a roofed internal gallery is visible inside its length, possibly turning to follow the east wall. At the northeast corner is an opening in the outer wall, into the gallery, 0.8m wide, 0.3m high above present ground level, with a triangular lintel.
There is a passage between H to the east and F & G to the west, interpreted as an entrance passage to a massive structure spanning the whole width of the stack. It is 1.1m wide, and along the entire width of H. The outer threshold has collapsed to the east, and is absent to the west.
Structure I
A large modern cairn on the highest point of the stack, probably a navigation aid.
Structure J
a construction c. 1.5m high by 1m side, 0.5m deep. Two rough piles of slabs with a large slab on top. Very recent, resting on topsoil
Structure K
a grassed-over linear mound, which could be the remains of a wall measuring 0.9m wide, funs 1.7m north south from the southern end of the wall to the west of structure C
Structure L
between E and the northeastern corner of H are the ephemeral remains of a possible wall c. 1m wide by 1.7m long. This may be a continuation to the south o the eastern wall of C, though it is very degraded and hard to interpret.
Structure M
a substantial revetment c. 2m deep and c. 6m long underlies and supports E, L and H, and runs along the southeatern flank of the stack. This may relate to the earliest phase of construction on the stack. It seals a steep gully or raving draining the summit plateau onto the eastern face. It appears not to have slipped or subsided at all.
Barrowman & McHardy, 2005, 40-59

Burgess, Christopher & Church, Michael, 1997, Coastal Erosion Assessment, Lewis. A Report for Historic Scotland (Bibliographic reference). SWE41000.

Name Book (County), 1998, Name Books of the Ordnance Survey, Book No. 26, 29 (Unpublished document). SWE4254.

Christopher Burgess, 2000, Lewis, Mesolithic to Modern: A study of site, settlement distribution and landscape formation in the Western Isles of Scotland (Unpublished document). SWE41053.

Council for Scottish Archaeology, 2004, Discovery and Excavation in Scotland (Bibliographic reference). SWE41193.

Chris Barrowman & Ian McHardy, 2005, STAC Severe Terrain Archaeological Campaign, Isle of Lewis 2004 (Unpublished document). SWE41102.