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Friday 17 June 2016

Rubh' An Dunain - 17 June 2016 - part 2

Chambered Cairn 

shown as a 'Horned Cairn' on the OS 7th series 1955-61 map

- which I guess was the current terminology for a cairn with a forecourt of orthostats.

from the NOSAS archaeology blog

Artist's impresson of Rubh an Dunain  Cairn in use (by Jean Williams in Prehistoric Scotland, (Macsween and Sharp 1989)






From Canmore:

Archaeology Notes

NG31NE 2 3934 1636.
(NG 3934 1636) Chambered Cairn (NR)
OS 6" map, (1965)
A Hebridean type round cairn with a polygonal chamber with antichamber and short passage, excavated by Scott in 1931-2 and left open.
The cairn, of large rounded stones, has a diameter of 62' to 66' and now stands 11' in maximum height. The S side has been heavily robbed, the peristalith and facade on this side being almost entirely destroyed. Where undisturbed, the cairn is covered with turf and heather.
The peristalith, revealed in a number of cuttings, consists of orthostats set 3' to 4' apart and linked with walling. The cairn material extends some 9' beyond the peristalith.
The forecourt is V-shaped in plan and measures about 24' across by 10' deep. Five feet in front of the entrance, there are two slabs lying at right angles to the main axis, the larger being wedged up to give a horizontal surface.
Finds, most of which are in the National Museum of Antiquities of Scotland (NMAS), included an N.4 beaker (EO 382), and from beneath an orthostat of the chamber, a possibly human foundation deposit.
W L Scott 1932; W L Scott 1934; D L Clarke 1970; A S Henshall 1972."




The 'Viking Canal'

July 2015 - higher tide
From Canmore:
"Field Visit (23 April 2009 - 9 May 2009)
NG 394 162 (centred on) An assessment survey was conducted 23 April–9 May 2009 following the discovery of medieval boat timbers on the northern edge of Loch na h-Ă€irde in 2000 and 2008. An aerial photography sortie facilitated by RCAHMS was conducted on 31 May 2009. Detailed surveys were conducted on the partly artificial channel 100m long which links the loch to the sea. Associated features include two nausts (stone-lined boat docks) which extend from its N side, close to the seaward end, and the tumbled foundations of at least three buildings. A promontory dun stands on a headland nearby (NG 396 159). Close to the centre of the canal is a blockage of stones, now tumbled but showing evidence of former structural cohesion. The margin of the loch follows the High Spring Tide contour, though its fill derives mainly from the surrounding catchment and is therefore partly fresh, with seawater entering only during extreme high tides. Although water now percolates through the blockage, the level in the loch remains largely constant throughout the tidal cycle.
A systematic search of the loch bed, most of which is less than 1.5m deep, was conducted with masks and snorkels. No further boat components were found, but a partly collapsed stone-built quay, now almost completely under water, extends on either side of the canal’s inshore mouth, with a gap in the middle. It was surmised that the canal was constructed so that vessels could be brought into and out of the loch, and water levels managed so that while there they would remain afloat throughout the tide, facilitating mooring or use of the quay. Since the process of bringing vessels into and out of the loch would have been quite complex, it seems likely that the system was intended for the secure over-wintering of craft, or for maintenance and perhaps boatbuilding on the loch’s shores.
One of the boat timbers found in the loch was probably from a clinker-built four-oared rowing boat c6m long. It has been radiocarbon dated to AD c1100. The other undated timber appears to be from a larger sailing vessel in the same tradition, perhaps more than 10m long. Neither craft could have had a local function in this tiny shallow loch, and were presumably there for safe-keeping or repair, or were being built. This implies that from at least the early 12th century the canal, blockage, and quay system, or some precursor of them, were in operation. Study of this remarkable maritime landscape is continuing, with research focused on determining the dates, associations and functions of the various features, including the dun.
Archive: RCAHMS (intended)
Funder: Historic Scotland
Colin Martin – Morvern Maritime Centre"


Dun / headland fort



from Canmore
From Canmore:
"Publication Account (2007)
NG31 1 RUDH' AN DUNAIN
NG/396160 (visited 20/4/63 and in 1986).

Description

Although unexcavated this promontory semibroch could be providing important evidence both for the dating of its type and for the significance of semibrochs in the evolution of the broch type, as is explained below. Its full excavation is highly desirable.
The wall of the structure is fairly well preserved and is certainly not a “ruined ring” as thought by Childe [3, 198]; the diameter of a circular building of which this wall was a part would be something like 40-45m (up to 150 ft) – two-and-a-half times the size of the average broch. The fact that the wall narrows considerably as it approaches the cliff at the north-east end (furthest from the doorway) appears to confirm that the wall was never much longer than it is at present. Of course a huge amount of the cliff would have to have disappeared over the last two-and-a-half millennia if the structure was once a complete ring.
The entrance in the convex outer wallface – which has a pronounced batter – is near the right or south-west end and is 3.6m (12 ft) from the high and sheer cliff edge; it is just over 3.66m (12 ft) long and filled with rubble. Its lintels have disappeared but the door-frame is visible 1.14m (3 ft 9in) from the outside, where there are two well-built, opposed rebates in the walls; the bar-hole is not visible.
In the inner face, a short distance to the left of the inner end of the entrance (looking inwards), is the door to the mural gallery which runs along the rest of the wall to the opposite edge. The left side of this door is continuous with the end wall of the gallery which thus stops several feet short of the main entrance. One lintel remains over the door but none are visible over the gallery itself. However its walls rise well above this lintel to the wallhead, which is here 10-12 ft (3.0-3.6m) high above the level grassy surface outside; thus an upper as well as a lower tier of gallery must be preserved. A fine ledge scarcement 9 in (25cm) wide is preserved on the inner wallface; it runs along more or less level. It is not clear whether this ledge included the lintel over the doorway to the gallery but it seems probable.
The space enclosed by the drystone barrier is now quite small, measuring about 250 sq yds., but the area of the promontory may have been reduced by cliff falls since Iron Age times. Very large angular rock fragments can be seen under water below the cliffs.

Structural analysis

It has been noted before that, although the promontory defence is a simple curved wall, its hollow construction is of equal sophistication to that found in the broch towers [3]. The entrance passage is of standard broch design and the wall to the left of this appears to have two continuous, superimposed galleries in it (Levels 1 and 2). It is reached by a doorway from the interior of which the front lintel would probably once have formed part of the scarcement on the inner face. Doubtless there is a stair to the upper levels just to the right of the door but no steps are exposed.
No doubt there was once a chamber over the entrance passage and a void over the gallery door, both facing inwards, but nothing of these is preserved. However the fact that the wall has such a shallow curve means that the scarcement cannot have supported a two-storeyed wooden roundhouse in the interior and it must have had some other purpose. In this way Rudh' an Dunain is sharply distinct from the round towers and from D-shaped semibrochs like Dun an Ruigh Ruaidh. Some further comments on its probable age are in 'Significance of the site' below.

....

The conclusion seems to follow that this promontory semibroch belongs to the early Iron Age and is also strongly supported by the evidence from Clickhimin in Shetland. A reassessment of the nature of the 'blockhouse' at that site, and of the associated pottery and artifacts, makes it extremely probable that that building is also a form of promontory semibroch which was constructed towards the end of the early Iron Age period, perhaps in the 6th or 5th centuries BC (site HU44 1, 89-115). The appearance of all the basic features of broch architecture in Atlantic Scotland at this early date is of great potential significance.
Rudh’ an Dunain and the two other very similar sites – Dun Grugaig, Skye (NG51 1), and Barra head (NL58 1) – show rather clearly that the high hollow wall was not originally designed as a protection for the multi-storeyed wooden roundhouse, which is what the tower broch seems to be. The curvature of their walls is much too shallow and the scarcements here must have supported some kind of two-storeyed range of buildings along its rear wall, as Hamilton envisaged at Clickhimin (site HU44 1).
...
Sources: 1. NMRS site no. NG 31 NE 1: 2. RCAHMS 1928, 144, no. 483, and fig. 296: 3. Childe 1930, 77: 4. Scott 1932, 185: 5. Scott 1934b: 6. MacKie 1965, pl. XVIII, upper, and XIX, left: 7. MacSween 1984-85, 51, no. 60 and pls. 14 and 15: 8. Tylecote 1962, 195-97.
E W MacKie 2007"

July 2015





We didn't have time to visit the cave or the abandoned settlement so retraced our steps round the northeast shore of the lochan.  Near the cairn we came across two mounds of stone which were very much the size and shape of sarcophagi.  Have we made a new discovery???


Heading back along the headland we followed the edge of this remarkable volcanic intrusion (or is it an extrusion?) - in places some 30 feet wide.


The moorland was also littered with huge erratics dropped by glaciers.  This one had then split - frost damage perhaps?

Another excellent expedition - thanks Joy!

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