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Ousdale Burn

Broch (Iron Age)

Site Name Ousdale Burn

Classification Broch (Iron Age)

Alternative Name(s) Lat 316

Canmore ID 7409

Site Number ND01NE 1

NGR ND 0713 1881

Datum OSGB36 - NGR


Ordnance Survey licence number 100057073. All rights reserved.
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Administrative Areas

  • Council Highland
  • Parish Latheron
  • Former Region Highland
  • Former District Caithness
  • Former County Caithness

Archaeology Notes

ND01NE 1 0713 1881.

(ND 0713 1881) Broch (NR)

OS 6" map, (1964)

A well-preserved second phase (ie. 2nd - 3rd century BC) broch measuring 50ft overall diameter and 24ft internally with walls 14ft thick at the entrance and 12ft on the opposite side, and 14ft high. The entrance passage, in the SW, is checked for two doors. Above it is a gallery, and a guard chamber is on its SE side. In this was found a 2ft square cist containing a cremation. A is in the wall entered from the courtyard 3ft from the entrance passage, and further round another entrance leads to a stair to a gallery above. At a height of 8ft from the floor is a scarcement ledge with corbel stones protruding at intervals of 8ft all round.

Outside on three sides is a well-built wall or rampart 8ft thick and fronted with a ditch; between this wall and the broch are signs of secondary occupation in the form of hut circles. During the excavation in 1891, MacKay (1892) found traces of secondary occupation within the courtyard at a height of 4ft above the broch floor.

J MacKay 1892; RCAHMS 1911, visited 1910; A Young 1964.

This broch is as described above. It is still in a fair state of preservation except for the outer defensive wall and the traces of hut circles within, which are all in an extremely mutilated state. The broch has an internal diameter of 6.9m and wall thickness of 3.6 to 4.4m, and a maximum external height of 1.5m. Inside it is 3.0 to 4.0m high in the N segment. The entrance is in the SW.

Visited by OS (W D J) 30 May 1960.

A well-preserved broch whose walls reach a maximum height of 1.5m externally and 3m internally.

C Batey 1982.

A broch with outer rampart and secondary occupation generally as described and planned by the previous authorities. The lintelled gallery above the entrance has collapsed. The entrance, mural chambers and the broch interior have been largely cleared of stones, and part of the inner wall-face has been reconstructed, possibly by the excavator. The removal of debris has weakened the structure and it is now in danger of collapse.

Visited by OS (N K B) 8 November 1982.


Project (1980 - 1982)

Field Visit (1982)

A well-preserved broch whose walls reach a maximum height of 1.5m externally and 3m internally.

C Batey 1982.

Publication Account (2007)


ND/0713 1881 (GPS – 07131 18802) (visited 12/7/63, in 1971, 10/7/85 and 24/7/03).

This well preserved, solid-based broch in Latheron, Caithness, stands on a narrow terrace at the foot of a long shallow slope (Illus. 7.002). This terrace is bounded on the north-east by a deep ravine containing the Ousedale burn flowing down to the sea and, on the south-east, by a shallower ravine containing the Allt a Bhurg ('the burn of the fort') which joins the former just below the site. There are high sea cliffs further down the slope. The broch terrace is dotted with ruined stone walls and small cairns. The site was excavated in 1891 by James Mackay [2] but only the interior was thoroughly cleared out, most of the outer wall being left buried. Presumably the few courses of the outer wall now visible always were exposed. The interior floor level is much lower than the present ground level outside so there is doubtless a considerable height of external wallface still buried. On the uphill side, where the entrance passage emerges, there is probably less; steps can be seen leading down to the entrance in an old photograph taken soon after the site was cleared, though they may show that debris accumulated against the foot of the tower in the Iron Age.


The main entrance is on the south-west and is 4.27m (14ft) long; nearly all the roofing lintels are still in position, the outer one being more massive and shaped like a truncated triangle. The passage is now 1.68m (5.5ft) high and 76cm (2.5ft) wide. There are two sets of door-checks – at distances of 1.14m (3ft 9in) and 3.13m (10ft 3in) from the exterior – each being formed of a long stone slab set into the passage wall and projecting from it. A guard cell opens to the right from between these doorways, its entrance being about 84cm (2ft 9in) high. The corbelled chamber behind it is almost complete and measures 2.59m (8ft 6in) long, 1.53m (5ft) wide and nearly 2.44m (8ft) high. A bar-hole behind the front checks runs through the wall into this cell; the bar socket is opposite it. Inside the guard cell the excavator found a cist 60cm (2ft) square and covered with flagstone; it contained "ashes, charcoal and a dark unctuous clay". [2, 353].

The seven lintels found roofing the entrance passage were described by Mackay as being 20cm (8in) apart but those observed by the author in front of the rear door-checks were only 2.5-5.0cm (1-2in) apart, hardly sufficient to make an effectively defensive meurtrière. The chamber over the entrance is still traceable throughout most of its length and was specifically described by the excavator: "A gallery runs the whole length of the entrance passage, the floor of the gallery being formed by the lintels, which are placed 8 inches apart…" [2, 353]. It appears to extend forward as far as the massive front lintel. However it was apparently much better preserved in about 1910 judging from the photograph in the Inventory [3. pl. XVIII] which shows the innermost lintel of the upper chamber still in position. However one has to conclude from the clear evidence for the reconstruction of the inner end of the passage (below) that this upper chamber has been partly restored though no such restorations are mentioned by the Commission [3] or in the excavation report [2].

It is clear that someone, presumably Mackay, restored the walling around the inner end of the entrance very soon after the excavation was completed; doubtless this was done to make sure that the upper parts of the broch in this important area did not gradually collapse after exposure, and in this sense the work was successful. The Royal Commission’s account [3] does not mention this restoration and it is easy to conclude that the photograph of the inner end of the entrance with the latter shows the structure as it was when it was uncovered. However Mackay under-took the consolidation himself.

“In carrying on the work of excavation the greatest care was taken not to injure any part of the tower which was still intact, and by strengthening it at a few weak points it should stand in its present condition for many years to come. His Grace the Duke of Portland has kindly fenced it in for better protection.” [2, 356].

A comparison of the old photograph with one taken in 1963 shows plainly that the walling at the inner end of the entrance is the same, except that the (presumably replaced) innermost lintel of the chamber over the entrance has fallen. It is particularly obvious that the edging blocks of the upper part of the left side of the doorway are the same in both photographs. The later one is clearer because it shows the end of the modern masonry a short distance clockwise from the passage and slightly overlapping the doorway to the mural cell.

This modern buttressing rises up to the present wallhead, a height of c. 3.4m (11ft). The straight joint against the broch wall is visible up to about 30cm above the lintel of the cell door, and thereafter the stonework is continuous; thus all the upper part of the inner face clockwise from the entrance for several metres is modern. Moreover the well-preserved, partly corbel-led ledge scarcement – 2.03cm (6ft 8in) wide – which runs round 2.44m (8ft) above the floor (now only 1.83m, or 6 ft, above the debris) is absent from 5-8 o'clock (around both sides of the entrance) even though the wallface is standing much higher than its level elsewhere.

The right inner end of the entrance is also rebuilt; the corner of the part above the passage lintels now contrasts sharply with the ruinous remains of the walls of the upper chamber. Thus one cannot be sure what original architectural features were found above the entrance lintels in 1891; one might guess that the excavator found the chamber over the entrance reasonably well preserved, with one probably dislodged lintel lying on the ground at the inner end, and so put it back on top of the restored walling.

The interior varies from 6.41-7.47m (21-24.5ft) in diameter, and a recent careful survey produced a figure of 3.33 +/- 0.05m (a diameter of 21.84ft). At 9 o'clock is the doorway to the mural stair with a stair-foot guard cell 1.98m (6.5ft) long opening to its left (Illus. 7.013); this cell is described as being "built in the usual beehive style, with stones overlapping" [2, 354]; rough corbelling can be seen in the photograph. The author omitted to check whether the cell is partly roofed – as it should be – with the lintels which would here form the floor of the Level II gallery.

There is an aumbry or small wall cupboard opposite the stair, and fifteen steps of the latter were found in 1891; these are now mostly covered by rubble and debris. The sills of both the doorway to the stair and that to the mural cell are raised about 60cm (2ft) and 45cm (18in) respectively above the present level of debris. There are the remains of a void over the stair door, and a human burial was found in this during excavation, lying face down. There are now no traces of a gallery on the present wallhead though whether this was cleared in 1891 is doubtful; Mackay does not mention doing this.

Clearly visible on the inner wallface for a short distance clockwise from the stair doorway at 9 o'clock is the scarcement; it is about at the level of the lintel over the doorway, in other words at the base of Level 2. Mackay did not mention this feature and the fact that he did not replace the ledge at the main entrance shows that its importance was not appreciated – perhaps that its existence was not suspected.

During the excavations it was observed that there was an upper floor in the interior, about 1.22m (4ft) above the primary floor level. Traces of flagstones were found set on edge in this upper floor the occupation on top of which may have taken place after the tower was partly in ruins [2, 354]. Presumably this secondary floor was entirely removed by Mackay.

The primary floor "consisted of two feet of fine puddled clay laid on the natural bed" (and presumably running up against the base of the wall). On this were layers of ashes and charcoal, with many broken animal bones many of which were half burnt with some split for their marrow. There were also large quantities of periwinkle and limpet shells and many wild hazel nuts. On this primary floor, and embedded in firm black clay, was an upright piece of wood possibly a post, bearing the marks of an axe. There was a series of tanks set into the floor (presumably the primary clay floor) made of stone slabs luted with clay; they were about 75cm (2ft 6in) square and 60cm (2ft) deep and were connected by a stone-built drain which led from the exterior to them, presumably downhill into the broch; the description is not clear and these features are not now visible.

Near the centre, and about 30cm (12in) above the floor, was a setting of four flags on edge forming what seems to have been a square fireplace. A covered V-shaped drain led from this to a vat in the floor near the stair doorway. This vat was 75cm (2.5ft) in diameter, and the same in depth, and it had been dug out of the natural bed: it was carefully lined with flags luted with clay and contained a 2.5cm (1in) thick layer of a clear green jelly-like substance at its base. A sample of this was analysed by Professor Japp of Aberdeen who found it to be probably humus formed by decomposed vegetation, probably peat, in contact with water. The vat may therefore have been a water tank.

The outer fortifications of the broch consist of a wall 2.44m (8ft) thick which runs round the broch on all sides except where the slope drops away to the burn below. There may have been a ditch outside this [2, 350] and there are signs of outbuildings inside this wall on the west.

Dimensions: (author's measurements). External diameter 6-12 o'clock, 15.33m (50.25ft); from 9-3 o'clock, 16.01m (52.5ft): internal diameter 6.56m (21.5ft) and 7.47m (24.5ft) respectively: wall pro-portion (from averages) 54.9%. In 1971 an accurate survey of the primary interior wallface was undertaken and this proved to have been built around a reasonably accurately laid out true circle with a radius of 3.33 +/- 0.05m (equal to a diameter of 21.84ft) .

Finds [2, 354-5: 5]. These include evidence of metalworking in the form of a crucible (a cup-shaped vessel the clay of which is burnt to a coke-like texture), and a mass of bone refuse with remains of sheep, deer, ox, hare and birds: no bone tools were recorded. Artifacts of stone included 1 damaged "hatchet" with a groove round its centre, 1 granite mortar, the hollow being 30cm (12in) across and 25cm (10in) deep, several crude querns, including at least one rotary form (no. 20), 3 discs of mica schist, 5cm (8in) in diameter, each with a 5cm (2in) hole in the centre, several whorls of sandstone and steatite, one decorated with two concentric circles of drilled pits, several whetstones and a segment of a jet armlet 9cm (3.5in) in diameter. Also mentioned are two quartzite pebble strike-a-lights.

There were also 'large quantities' of native pottery including two rims of vases with slightly out-turned lips and made of hard grey clay. There was also a fragment of a wooden dish or scoop with an everted rim, 13cm (5in) in diameter and 5cm (2in) deep.


There is no doubt that – despite the early date of the exploration of this site, and despite the work of restoring and shoring up the old drystone stonework – this was a hollow-walled broch tower of the usual type. However it has been pointed out that the material culture found inside it is an interesting blend of the mainland and the Atlantic Iron Age traditions [4]. While many sherds of Atlantic pottery were found, the rest of the material culture is of stone and very sparse. Missing entirely are any of the many characteristic bone artifacts of the maritime broch province and this is despite the fact that many well preserved animal bones were found. It is suggested that Ousedale Burn is near the boundary between the maritime zone and most of the brochs of the north-east mainland (except those in the north-east tip of Caithness); the latter were evidently built for an entirely different archaeological culture [4].

Sources: 1. NMRS site no. ND 01 NE 1: 2. Mackay 1892: 3. RCAHMS 1911b, 54-6, no. 204, fig. 12 and pl. 18: 4. MacKie 2000: 5. Young 1964, 174, 197; 6. Proc Soc Antiq Scot 26 (1891-2), 260.

E W MacKie 2007

Note (March 2017)

The Broch

Walk a mile east from the hustle and bustle of the A9 at Ousdale, in Caithness, and an almost- forgotten realm of tranquillity can be discovered. Here, the shunts and grunts of traffic dissipate, and are replaced by the calls of grouse and pheasant, and even the occasional startled deer. 2000 years ago, however, and this area would have sounded and looked much different, habited by humans, and dominated by the presence of a stunning prehistoric structure – the broch.

Brochs are multi-storeyed, drystone tower structures. They are ‘double walled’, with a staircase running through the ‘gallery’ between these walls. These ancient buildings, most of which now lie as ruinous mounds of earth and rubble, are often punctuated with features such as corbelled cells built within the walls, voids (perhaps included to lessen the weight load), door checks, internal staircases and even wells – however, given that there are thought to be around 500 of these monuments in Scotland, their appearance differs from one broch to another. Brochs appear to have been the final conclusion in roundhouse building in Scotland, from roundhouses and hut circles built from around 2000 BC, to Atlantic Roundhouses and Complex Atlantic Roundhouses, before finally brochs appear, from around 200 BC.

What is evident is that brochs would have been imposing structures on the landscape in any form, with some brochs reaching up to 40 feet high – it is no surprise, then, they are often referred to as the ‘pinnacles of prehistoric architecture’. For those wishing to get an idea of how impressive these brochs would have looked, then travel to the Shetland Islands, specifically the island of Mousa, where the best-surviving example exists.

Brochs are unique to Scotland, but Caithness can lay claim to having more brochs than anywhere in the country, with over 180 broch sites having been identified in the area. What made Caithness ‘the home of the broch’? It is difficult to truly pinpoint why the north of Scotland was such as ‘broch hotspot’, but Martin Carruthers, who has been investigating ‘The Cairns’ broch site in Orkney for several years, believes it is down to a number of factors:

"I think it comes down to long-lived excellent building traditions in stone, plus the social and economic context for large populations who were also in competition with each other. Lots of evidence now that they were able to seriously improve their environment through enhancement of soils etc, to really boost fertility and productivity.

Beyond these factors, though, I think you've just got to take into account the shear land mass of Caithness. It's a massive block of land, and there's plenty of good farm land within that block. It's a much larger land mass than is available in the Northern or Western Isles, so it could presumably sustain a pretty big population."

Allt a’Bhurg (Ousdale Burn broch)

Despite the large number of broch sites in Caithness, there are relatively few examples in good condition – of which Allt a’Bhurg (also known as Ousdale Burn broch) may be considered to be the best. Caithness was subject to a flurry of archaeological activity during the mid 19th and early 20th centuries, and Allt a’Bhurg was excavated by James Mackay in 1891. A number of finds were made, including fragments of pottery, polished lignite, quern stones and whetstones – but most intriguingly, a human skeleton was discovered buried face-down by the entrance to the stairs. What could this burial have represented? Was this a respected member of the broch-family, or someone who would protect the broch in the afterlife?

Brochs often poise more questions than there are answers – but what is clear is that Allt a’Bhurg broch was an important, imposing and influential prehistoric monument. The broch’s name reflects this: the broch gave its name to the nearby stream, Allt a’Bhurg, which is Gaelic for ‘River of the Borg’. The term ‘Borg’ is the Old Norse name for these structures, from which the word ‘broch’ has been derived. Besides this, just a hundred feet or so from Allt a’Bhurg is the post-Medieval clearance village of ‘Borg’. Despite this village being built hundreds of years after the broch falling out of use, the name clearly demonstrates the reverence the broch had been afforded by local inhabitants through the ages - and it still has the power to impress today.

Allt a’Bhurg, however, has suffered recent structural collapses, and is a shadow of what it once would have been. Caithness Broch Project, a local archaeological charity seeking to promote Caithness through its archaeology and broch sites, however, are looking to protect, conserve, consolidate and interpret this site for future generations, and are working with organisations such as Historic Environment Scotland and Archaeology Scotland to help save the broch.

To find out more about Caithness Broch Project and their other exciting projects, please visit, or follow them on Facebook, Twitter or Instagram. You can also contact them by emailing

Kenneth McElroy - Caithness Broch Project

Watching Brief (September 2019 - March 2020)

ND 0713 1881 Between September 2019 and March 2020 archaeological surveys and watching briefs were undertaken at Ousdale Broch, on behalf of the Caithness Broch Project, as part of a project to consolidate and improve access to the Scheduled broch (SM515: Allt a’ Bhurg, Broch, Ord of Caithness). Relatively recent collapse of a stone buttress, built in the late 19th century to stabilise a portion of the internal wall, led to large amounts of rubble existing in the broch interior and an increased risk that the structure could further deteriorate at a rapid rate. The archaeological works included a pre- and post-conservation survey of the broch and watching briefs during removal of collapsed material from the broch interior, consolidation of the wallhead and removal of a mature rowan tree which grew out of the interior elevation. No significant buried archaeological remains were disturbed during the work.

Archive: NRHE (intended)

Funder: Caithness Broch Project

David Sneddon – Clyde Archaeology

(Source: DES Vol 21)


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