Ancient Monuments

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Dun, Eilean Loch Arnol

A Scheduled Monument in An Taobh Siar agus Nis, Na h-Eileanan Siar

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Latitude: 58.3463 / 58°20'46"N

Longitude: -6.6141 / 6°36'50"W

OS Eastings: 130124

OS Northings: 949013

OS Grid: NB301490

Mapcode National: GBR B61N.Z41

Mapcode Global: WGX14.CHN0

Entry Name: Dun, Eilean Loch Arnol

Scheduled Date: 26 March 2024

Source: Historic Environment Scotland

Source ID: SM13787

Schedule Class: Cultural

Category: Prehistoric domestic and defensive: crannog

Location: Barvas

County: Na h-Eileanan Siar

Electoral Ward: An Taobh Siar agus Nis

Traditional County: Ross-shire


The monument comprises the remains of a dun, a prehistoric defended settlement, in this instance constructed on a wholly or partially artificial island with a causeway linking it to the loch shore. The dun is likely to have been constructed during the Iron Age (800BC – 800AD) and reused during the medieval period. The dun is located around 30m south of the northern shore of Loch Arnol, a small loch located at around sea level near the north coast of Lewis.

The dun is visible on a small, roughly circular island, around 20m in diameter, covered in long grass with large turf-embedded stones scattered across the surface. The grass stops about 1-2m from the water's edge, and this shore edge is all stone, with evidence of coursed wall face in places. This is typical of other island duns on Lewis. The profile of the site is roughly conical with a hollow top, with any built structures rising to a point north-east of centre of the dun. The hollow top is presumably the centre of a dun. A concentration of large stones lies at the north end of a raised area, with at least one longer, possible lintel stone, present. Aerial photographs indicate a possible rectangular walled structure with rounded ends, which is likely to date to the medieval period, occupying the centre of the site. The causeway extends from the northwest quadrant of the island and curves westward before connecting to the loch edge at the closest rounded promontory. It is around 27m long and 2m wide, built of stone and is only visible when the water level within the loch is low. 

The scheduled area is irregular. It includes the remains described above and an area around within which evidence relating to the monument's construction, use and abandonment is expected to survive, as shown in red on the accompanying map.

Source: Historic Environment Scotland

Statement of Scheduling

The national importance of the monument is demonstrated in the following way(s) (see Designations Policy and Selection Guidance, Annex 1, para 17):

a.   The monument is of national importance because it makes a significant contribution to our understanding or appreciation of the past. As a well-preserved example of an island dun with a causeway and with evidence suggesting multiple periods of activity it has the potential to contribute to our understanding of the construction and use of island structures from the later prehistoric and later periods.

b.   The monument retains structural, architectural, decorative or other physical attributes which make a significant contribution to our understanding or appreciation of the past. In particular, the partially submerged nature of the site means there is a high potential for the preservation of organic material relating to the site's construction and use that rarely survives outside of waterlogged contexts.

d.   The monument is a particularly good example of an island dun which appears to have been re-used at a later period and is therefore an important representative of this monument type.

e.   The monument has research potential which could significantly contribute to our understanding or appreciation of the past, including the use of artificial islands for settlement and other purposes within Scotland.

f.   The monument makes a significant contribution to our understanding of the historic landscape as it appears relatively undisturbed as a prehistoric settlement site within what is now a remote and sparsely populated rural area. 

Assessment of Cultural Significance

This statement of national importance has been informed by the following assessment of cultural significance:

Intrinsic characteristics (how the remains of a site or place contribute to our knowledge of the past)

This island dun is a well-preserved example of the monument type, showing evidence of its initial construction and use and of later reuse. Artificial, or partially artificial, island settlements are found in many parts of Scotland, and are often referred to crannogs, and more specifically, island duns for those found in the Outer Hebrides. This example is constructed of a mix of medium sized stone and large boulders, with much of the structure below the water level of the loch. It is connected to the north shoreline of the loch by a stone-built causeway that would have provided access onto the artificial island. This is now usually only visible during drier periods.

Archaeological investigation at similar sites such as Dun Bharabat, Isle of Lewis (Canmore ID 4020, Harding and Dixon 2000) or Eilean Domhnill, North Uist (scheduled monument SM5238) has demonstrated that the submerged parts of the monument have a high potential to preserve significant archaeological remains, including organic material relating to the construction and use of the site that would be highly unlikely to survive outside of the waterlogged conditions.

The presence of a rectangular structure on the islet is indicative of a potential later period of reuse, which is commonly found on crannogs, such as at Loch An Duna (scheduled monument SM5349). The later reuse of a crannog site generally dates to the medieval (1000-1500AD) or post-medieval (1500-1600AD), although evidence from some sites has found them in active use as late as the early modern period (1600-1750AD), and archaeological evidence from the site may provide a clearer understanding of the purpose and date of the later use.

The causeway connecting the island to the shore is a feature that is relatively common in Hebridean island duns, such as at Loch An Duin (scheduled monument SM3264) and Loch na Muilne, South Uist (scheduled monument SM5331), while others appear to have accessed by bridges or boat. There are also likely examples of crannogs where the remains of causeways are no longer extant and/or visible. The causeway is c. 27m long and 2m wide and wholly composed of built stone. It is apparently visible and accessible during drier spring and summer months. It is not clear if the causeway in this example dates to the original phase of construction and use or to its later reuse, and archaeological evidence from the site may provide a clearer understanding of its date and construction.

The Loch Arnol island dun has the potential to enhance our understanding of the past, in particular the construction and use of artificial islands within Scotland in prehistory and their later reuse. It is likely that the submerged parts of the site retain important structural, artefactual and environmental material, possibly including fragile organic remains which do not normally survive on non-waterlogged sites. The loss of the monument could affect our ability to understand the development of island settlements and their significance for communities inhabiting the western isles and western Scotland from later prehistory onwards.

Contextual characteristics (how a site or place relates to its surroundings and/or to our existing knowledge of the past)

The monument is one of over 385 recorded crannogs and related structures, including island duns, recorded across Scotland, 197 of which are found in the Outer Hebrides (Blankshein et al. 2023). There are also significant concentrations of crannogs and island settlements in southwest Scotland, Argyll and the inner Hebridean islands, and they are to be found on many freshwater lochs, while others are found in estuarine locations. Most of such sites are believed to date to the Iron Age (800BC-400AD), although some examples in the Western Isles, such as Eilean Domhnuill (scheduled monument SM5238) in Loch Olabhat, North Uist, are now known to date to the Neolithic period (4100-2500BC).

Duns are a relatively common monument type and are widespread across Scotland. The National Record of the Historic Environment records over 1700 examples entries for duns, around 180 of these are in the Western Isles. Due to its meaning of 'fort' in Scots Gaelic the word 'dun' appears in the name of many similar settlement types such as brochs, hillforts and enclosed settlements and island dwellings such as in this example.

The monument is located near the north coast of Lewis around 30m from the northern shore of Loch Arnol. The loch is found in open moorland between Bragar and Arnol at around sea level.

Associative characteristics (how a site or place relates to people, events, and/or historic and social movements)

There are no known associative characteristics that contribute to this monument's national importance.

Source: Historic Environment Scotland



Historic Environment Scotland reference number CANMORE ID 131420 (accessed on 19/01/2024).

Local Authority HER/SMR Reference 3226 (accessed on 19/01/2024).

Blankshein, S, Gannon, A, Garrow, D and Sturt F (2023). "Neolithic Crannogs in the Outer Hebrides (and Beyond?): Synthesis, Survey and Dating", in Proceedings of the Prehistoric Society. Cambridge University Press pp. 225-247.

Harding, D W and Dixon, T N (2000). Dun Bharabhat, Cnip: an Iron Age settlement in West Lewis. Edinburgh, University of Edinburgh.

Harding D W and Gilmour S (2000). The Iron Age settlement at Beirgh, Riof, Isle of Lewis: excavations 1985. Volume 1: the structures and stratigraphy. Edinburgh, University of Edinburgh.

Garrow, D. and Sturt, F. (2019) "Neolithic crannogs: rethinking settlement, monumentality and deposition in the Outer Hebrides and beyond," in Antiquity, Cambridge University Press, 93(369), pp. 664–684. Accessed online at (PDF) Neolithic crannogs: rethinking settlement, monumentality and deposition in the Outer Hebrides and beyond (

MacLeod Rivett, M (2021). The Outer Hebrides. A Historical Guide. Birlinn, Edinburgh.


Source: Historic Environment Scotland

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