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Publication Account

Date 2007

Event ID 1039113

Category Descriptive Accounts

Type Publication Account

Permalink http://canmore.org.uk/event/1039113

NC80 2 CARN LIATH 1 (‘Dunrobin’)

NC/871013 (8704 0137 – GPS).

(...continued from part 1 Event ID 586921)

Clear secondary constructions

These include the wall added around the interior – which was not identified on Joass’ plan – and a number of external buildings and features. The internal secondary wall is about 46cm (18in) thick and runs all the way round the court, with apparently original gaps in it in front of the two doors; after modern consolidation its width varies between about 0.6-1.5m (2.5ft). This was probably the “scarcement” referred to by Joass; 19th century broch excavators often used the same term to describe both a secondary wall and the ledge on the inner face of the primary wall. Extensive restoration has taken place at the stair doorway (which was blocked off in the early '70's [1]) and this has resulted in the primary and secondary masonry of the left side of the stair doorway now being continuous, the assumed straight joint having been obliterated. Likewise the lintels over this doorway have been replaced wrongly, with three superimposed, whereas there was almost certainly a void here; such a feature is suggested – though not absolutely clearly – by Joass’ cross section and is a standard feature of stair doors in other brochs.

Corcoran examined the secondary wall in 1972 and observed that its foundations rested at a higher level than the lips of the central underground chamber and on “a well defined layer of moist charcoal” [9, 159]; the date of this wall relative to the broch was thus confirmed.

He also discovered five previously un-recorded post-holes, on the south and south-west sides of the central court and fairly close to the secondary wall. Two more, much shallower, depressions which might have been post-holes were found in the north sector. These are assumed to be secondary features, apparently because they are “not of the proportions to have supported timber uprights for an upper floor or gallery” [9, 160] but no dimensions were published. Taking account of the thickness of the secondary wall four of the post-holes in the southern arc might have formed part of an irregular arc suitable for some kind of internal wooden roundhouse, though they are certainly not as regular, nor apparently so massive, as the ring of posts inside, for example, Leckie (NS69 2) and Dun an Rhiroy (NH19 3).

Outside the broch there are a number of wallfaces, approximately concentric with the tower, on the north-west arc and some polygonal chambers abutting against the broch wall on the north-east, immediately to the right (north) of the entrance.

An important feature, found at many other brochs, is the secondary passage – with door-frame included – which has been added against the outer end of the entrance [9, pl. 4, left and right]. This door-frame is evidently at the inner end of a long extension east of the main entrance most of which has now disappeared. At the junction with the broch wall another passage turns south from this passage and runs along the outer face of the tower. The usual explanation of such features is that the addition of this new door housing means that, at a later stage in the history of the broch, the primary door had become broken down and useless, probably after the upper works of the tower had been demolished (MacKie 1995). Some of these external features were examined by Love (below).

The recent excavations [9]

There was apparently some unauthorised clearance of the broch interior by a school party in 1971 and this led to fresh excavations by the late John Corcoran in 1972, the results of which have been alluded to above. Shortly afterwards the site was taken into state care. The early death of the excavator prevented him publishing his work although numerous photographs of the features he uncovered are in the National Monuments Record (Corcoran's Day Book (diary of the excavations) is also with the NMRS). New excavations took place in 1984 and 1986-87 in order to find out if any undisturbed deposits remained in and around the broch, and also to make the site more comprehensible to visitors; summaries of Corcoran's discoveries are given [9].

The only new work inside the broch took place in the guard cell, which had been blocked up in the late 1960s because of increasing dilapidation. This was re-exposed and consolidated, and a complete Iron Age pot base was found on the floor (not illustrated in the report). In addition the northern pit in the central court was cleared out [9, pl. 8].

Extensive new excavations were under-taken in the “outbuildings” surrounding the broch. However it was clear that the Victorian diggers had disrupted the stratified deposits over large areas and it was difficult to arrange the structures in their correct relative order [9, 10].

Rock carvings and calendar orientations

One of the several lintels which then roofed the secondary extension of the entrance passage was found to bear three cup-marks on its upper face [3, 104] (these stones cannot now be located). Assuming that this secondary doorway was originally more massive, these lintels would have been covered by masonry and would probably have been invisible before the ruination of the site. Thus it is difficult to be sure whether the later builders attached any importance to the cup carvings. There is some evidence that cup-marks, and even cup-and-rings, were still being carved in the late Bronze and early Iron Ages (Morris 1989, 58 ff.: MacKie and Davis 1989, 142 ff). Presumably this stone had been brought from elsewhere to form part of the roof.

A few years later other lines, presumably pecked, were observed on the same lintel [10]. One group of these consisted of two long, pointed ovals, joined end to end and about 9cm (3.5in) in length with a straight line 4.5cm (1.75in) long below this. When the lintel was still in situ the orientation of these lines was measured with a compass and it then appeared that the straight line pointed due north-south and the ovals north-west and south-east [10]. The discoverer, believing (for unstated reasons) that the broch builders were probably sun-worshippers, surmised that the long ovals indicated the directions of midsummer sunset (in the north-west) and midwinter sunrise. The carved lintel cannot now be located on the site and is doubtless buried.

Assuming that Wise's diagram was based on a rubbing and is therefore accurate, one can measure the angle of the supposed north-west/south-east line in relation to the assumed north/south marker. The angle is close to 312o/132o, presumably in relation to magnetic north. Making allowances for the difference between magnetic and true north in 1880 (when the former was 21o west of the latter) the actual azimuth should be about 3133o/153o. At the latitude of Golspie (almost exactly 58o north) the azimuth of the midwinter sunrise at altitude 0o is now about 141o. Sunrise on the first sixteenth of the solar year before and after the winter solstice (Thom 1967, Table 9.1) occurs here on an azimuth of about 133o, much closer to the position indicated by the carving. However whether one can assume such an intention with such evidence is another matter. A pointer to sunrise on the first eighth of the year before and after the winter solstice (Feb. 1st and Nov. 1st) would be more plausible and would have many more parallels in Neolithic monuments (MacKie 2002).

Of course there are no means of knowing whether Wises’s diagram does show magnetic or true north. The author has not yet had an opportunity to measure the Aberdeenshire horizon from Carn Liath, but such an exercise might prove fruitful and might show some plausible horizon markers for calendar dates.

Structural Analysis and Discussion

Pennant's 1769 description makes it clear that two hundred and thirty five years ago Carn Liath looked like the stump of a tower projecting above a heap of rubble. His description of the three “low concentric galleries … covered with large stones” can only refer to superimposed and still lintelled galleries between the outer and inner elements of the hollow wall, which were 4-5ft thick. Since Carn Liath is now known to be a solid-based broch all these galleries must have been upper ones, resting on the solid base. The discovery in about 1868 of a chamber over the broch entrance confirms the diagnosis.

Level 1: the ground level storey contains the entrance passage just north of east and the doorway to the stair (without a guard cell) at 10 o'clock, on the south-west. Simply from the available space it seems possible that there may be an undiscovered intra-mural cell somewhere but specific evidence is lacking.

Levels 2-4: the nature of the first floor (Level 2) gallery is complicated by the existence of what appears to be a long cell running across the entrance passage. If this was a primary feature it is difficult to understand the need for it unless it was designed as two sideways extensions for the chamber over the entrance, but such openings in the sides of the latter were not referred to by Joass. By the time the broch stairway came round from 10 to 6 o'clock it would have risen high above these potential obstructions. It is possible however that, after the upper levels of the broch were in ruins (and the entrance passage perhaps blocked), a long chamber was constructed on the low wallhead at this point. A small such chamber was built into the raised mural galleries, after ruination, at about 1 o'clock at Midhowe and at Gurness in Orkney (HY33 1 and HY32 2).

There were doubtless several tiers of galleries above Level 2 but nothing of these survives.

The central underground chambers: the curious sunken chambers or cellars inside the broch are such an unusual feature that they require some explanation, particularly as their situation would appear to interrupt the course of the ring of posts of any internal roundhouse and the positioning of the standard broch fireplace in the centre. As Joass observed [3, 103] the design of the sides of these chambers – flat orthostats with dry walling on top – strongly resembles some of the chambered tombs further north in Caithness. Unfortunately such a resemblance could not be confirmed from the modern re-excavations which were not completed due to safety considerations, but underground chambers inside brochs which are clearly not wells or cisterns (being cut into sand) are sufficiently unusual to require some kind of explanation.

From the discoveries at Howe in Orkney (HY21 6) we now know that, very occasionally, a broch or broch-like building could be deliberately sited on top of an ancient Neolithic chambered tomb and that a part of that tomb – in this case an underground chamber – was inside the building, open and accessible. The feeling that a succession of Iron Age buildings were put up on this unstable site for primarily religious reasons is very strong at Howe [11].

Much closer geographically to Carn Liath is the broch at Dunbeath (ND13 6), about 42km to the north-east, where there seems to be a very strong likelihood that one chamber of a Neolithic tomb was incorporated into the broch wall and used as an open chamber; if so the rest of the tomb must have been pulled down before the broch was put up, as could also have happened at Howe.

Could the two large underground chambers at Carn Liath therefore be the remains of the underground parts of a now vanished Neolithic tomb, and could this broch therefore have been primarily a religious site as Howe seems to have been? Despite the general similarities with some Caithness tombs – seen in the orthostatic walling surmounted by drystone masonry – it seems improbable for four reasons.

The first is that underground chambers seem to be extremely rare in Scottish Neolithic tombs, so there would surely hardly be two such in the assumed Carn Liath tomb. The second reason is that these particular chambers are not well built, being in part hollowed out of soft sand with single layers of stone revetment forming the sides. The stone-work of Neolithic chambered tombs is generally of extremely high quality (the slabs facing the passage and chambers usually having been freshly quarried) and any underground compartments would surely not have been any less well built, particularly as a jerry-built, below-ground part would surely have compromised the stability of the heavy tomb.

The third reason is that everything about Howe is unusual, especially the design of the 'broch' which was planted on unstable clay foundations and could never have been a high, hollow-walled tower (it had a wall core also partly of clay); there were several signs of wall collapse. Carn Liath by contrast is a classic solid-walled, stone tower broch of the standard kind and – again in contrast to Howe – there is no reason to single it out from all other such except for the underground chambers. The fourth reason follows on from this. In its primary state Carn Liath should have had in its central court a large stone hearth (in the middle) as well as a massive wooden roundhouse resting on a ring of posts (of which there may be some traces) and on the scarcement in the primary wall. The positioning of the underground chambers is incompatible with such a design and indeed an apparently secondary fireplace was found on the north side of the interior [9, pl. 2, upper].

For all these reasons it seems most likely to the author that the deep chambers at Carn Liath are secondary inserts. They may be simpler versions of the deep and elaborate underground, often rock-cut chambers found in many Orkney and Caithness brochs which are usually described as wells. However they are likely to have had a more complex function than water storage (below).

The secondary constructions: the presence of the secondary internal wallface and of the outward extension of the entrance passage implies – judging from analogies with many other sites – that at some stage the high, hollow wall of the broch was taken down (the debris presumably being used to construct the secondary wall which supported the new low roof). The entrance must also have been damaged at some stage since it needed a new door-frame in its outward extension. Since this secondary passage runs through some outbuildings these too may all be secondary, though one cannot be sure about this. Despite the recent excavations we still lack much insight into what these 'outbuildings' were used for.

If the underground chambers were added inside the reduced broch at this stage it is possible that the site then acquired a more ritual function, or that a previous primary such function was enhanced during the secondary occupation. A tiny clue to the nature of such ceremonial activity may be provided by the curious carving on one of the lintels of the secondary entrance passage which rather clearly suggests a concern with the solar calendar, particularly with midsummer and midwinter. Indeed one might conclude that this secondary carving also supports the allocation of the underground chambers to the later phase of occupation of the broch. The fact that Carn Liath is situated on the shore with clear views across the sea to the north coast of Aber-deenshire could confirm that the site was sometimes used as some kind of simple calendar observatory, with long alignments to the uneven, distant horizon to the south-east providing some useful calendar dates. More work needs to be done on this aspect of the site.

The excavations and the finds

Joass [3] describes the deposits inside the broch as consisting of 90cm (3ft) of "unctuous earth" and ash strata resting on the floor and surmounted by 3.05m (10ft) of stony debris. We must assume that much of this 3ft-deep occupation layer accumulated during the secondary occupation but unfortunately no-one thought to make a note of how this deposit related to the base of the secondary wall. The wall above these floor deposits was apparently fire-marked.

The finds [3, pl. xvl] are in the Dunrobin Castle museum and the most important included the following:

Bronze objects included 2 heavy plates with hammermarks on both faces (found near the floor).

Bone objects included 2 long-handled combs, 1 whalebone 'club' and much food refuse.

Stone objects included many hammer-stones, 2 long pestles (inside the broch), 3 mortars (outside), about 12 rotary querns (inside and out), pot lids (in and out), spindle whorls (in and out), 1 possible loom-weight, 1 sandstone slab with pecked concentric rings (on broch floor), 2 small steatite cups (one handled) (inside), many shale rings with diameters of 0.25-3.0in., in all stages of manufacture (inside and out).

Romano-British finds: there was also a silver fibula the ornament on the stem of which is thought to derive from 4th century Roman brooches [5, 392 and 337, fig. 36, nos. 5 and 6]; it may however be later and date to the 7th century [1]. It was found “outside the broch” [6, 392].

Finds made by Corcoran and Love in their excavations are not published in detail. As regards the latter they –

"…were relatively few and generally undistinguished, the more outstanding artifacts having been collected by the Third Duke in 1868. The majority of these are now in Dunrobin Castle Museum, although some have been misplaced. Unfortunately, disturbance on site has meant that few of the finds from recent excavations have been securely stratified. They can only therefore be regarded as representative of activities on site, domestic and industrial, rather than as useful chronological indicators tied into stratigraphy.

Domestic occupations were represented by a variety of artifacts – spindle whorls, bone needles, perforated weights or sinkers, and pottery, the latter predominantly undecorated Iron Age coarseware, with the notable exceptions of the Beaker fragment and Food Vessel. Shale objects were ubiquitous across the area excavated, occurring in such quantities as to indicate that jewellery manufacture was taking place on site. Various stages of production were represented from waste flakes through to roughed-out armlets complete with chisel marks, and finally to the end product, polished beads and rings. As evidenced by the small, undecorated, perforated disc washers from the cist burial, this medium enjoyed a protracted popularity, with local supplies of the raw material outcropping on the beach at Brora, a short distance up the coast.

Iron working was also represented in the form of crucible fragments and numerous lumps of iron slag from both outbuildings and midden. There were few personal objects found however, save for a couple of glass beads, one clear, the other spherical with a decorative whorl design, and the shale washer necklace associated with the Food Vessel burial" [9, 169].

Dimensions (taken by the author in 1963):

Ext. Diam. Internal Diam. Wall prop. %

6-12 o'clock 67.0ft 32.5ft 51.5%

9-3 o'clock 72.0ft 27.5ft 55.6%

Average 69.5ft 30.0ft 53.5%

A fresh survey of the shape of the central court was undertaken in 1971 and showed that the primary wall is almost exactly circular; the radius of the circle which fits it best is 5.10 +/- 0.09m, or 33ft 6in. The difference from the 1963 taped dimension from 9-3 o'clock was probably due to difficulties in distinguishing between the primary and secondary wallfaces at that time.

The wall proportion can now be estimated, using the average overall diameter, at 48.2%.

Sources: 1. NMRS site no. NC 80 SE 4.00: 2. Anderson 1883, 221: 3. Joass 1890: 4. Anderson 1901, 117, fig. 3: 5. RCAHMS 1911a, 91-2, no. 270: 6. Curle 1932, 337-38: 7. Young 1962, 182: 8. Robertson 1970, table 2: 9. Love 1991: 10. Wise 1881: 11. MacKie 1998: 12. Close-Brooks 1995, 12, 134 and 147: 13. Cowley 1999, 71: 14. Armit 2003, 14, 151 and pl. 11.

E W MacKie 2007

People and Organisations

References