Proc Soc Antiq Scot 141 (2011), 103–124 AN IRON AGE CRANNOG IN SOUTH-WEST SCOTLAND | 103 An Iron Age crannog in south-west Scotland: underwater survey and excavation at Loch Arthur Jon Henderson* and Graeme Cavers† ABSTRACT As part of the second phase of the South West Crannog Survey, the crannog in Loch Arthur, New Abbey, Dumfries and Galloway, was surveyed and small-scale excavations were carried out on submerged eroding deposits. The crannog was seen to be at threat from erosion for a number of reasons, including insect infestation, aquatic plants and wave action. The eroding deposits were sampled and their ecofactual content analysed and structural timbers from various positions in the crannog mound were radiocarbon dated. The results suggest that the site is a massive packwerk mound that was constructed in the second half of the 1st millennium BC, most likely in one event. After an apparent period of abandonment, the site was reoccupied in the later medieval period. INTRODUCTION crannogs generally, giving the study of the excavated deposits at Loch Arthur crannog Underwater survey, excavation and presented here an added importance in terms monitoring was conducted on an artificial of the overall development of crannog studies island or crannog in Loch Arthur from (Crone et al 2001). 2002 to 2004 as part of the second phase of the South West Scotland Crannog Survey (Henderson et al 2003; 2006). The work was H ISTORY OF RESEARCH conducted primarily to evaluate the condition and stability of the organic deposits surviving Loch Arthur is located in south-west on the site prior to the establishment of Scotland, in the parish of New Abbey an environmental monitoring programme. c 10km south-west of Dumfries (illus 1). The Crannogs are a much understudied resource loch is approximately 915m in length by a in Scotland and the underwater excavations maximum of 460m in breadth; it covers an conducted at Loch Arthur are only the second area of 30 hectares and at its greatest depth to have been carried out in the country and is approximately 15m deep. The loch contains represent the first such investigations in just one crannog situated close to the northern south-west Scotland. Little is known about shore at Nat Grid Ref NX 9028 6898. The the construction and taphonomy of Scottish crannog appears above water as a small tree- * Underwater Archaeology Research Centre, Department of Archaeology, School of Humanities, University of Nottingham, Nottingham † AOC Archaeology Group, Edgefield Road Industrial Estate, Loanhead, Midlothian 104 | SOCIETY OF ANTIQUARIES OF SCOTLAND, 2011 N 0 1000m 500 z➣ Beeswing Crannog Loch Arthur Illus 1 Loch Arthur, New Abbey – location map covered island, some 30m in diameter, and recovered from the loch, the precise location is connected to the shore by a muddy reed of which was not recorded. bed. The island first came to the attention of The island attracted attention again during archaeologists between 1840 and 1844 when the hot summer of 1874 when the level of two medieval bronze tripod cooking pots were Loch Arthur was exceptionally low: AN IRON AGE CRANNOG IN SOUTH-WEST SCOTLAND | 105 [The island] is about 100 feet in diameter, and In 1989, the site was visited and dived is approached by a stone causeway about 30 as part of the South West Crannog Survey yards long, which was laid bare last summer Phase 1 (Barber & Crone 1993: 527). A (1874) by the lowness of the lake. The artificial vertical birch (Betula sp) pile off the northern nature of the island may be seen by the remains side of the site was sampled for C-14 dating of the oaken piles driven in rows, with horizontal beams between, which can still be traced in and provided evidence of Iron Age activity at the water round the north-east and south sides. the site (GU-2463, 2260 ± 50 bp, calibrating The lines of two small enclosures can be at 400–200 bc; GU-2644, 2240 ± 60 bp, followed on the south side of the island (Gillespie calibrating at 410–160 bc). 1874–6: 23). The current phase of work in Loch Arthur reported here is part of the South West A large dug-out canoe featuring an elegant Crannog Survey Phase 2 (Henderson 2004: animals-head prow was discovered at this 175–9). The first phase of the survey, carried time, on the shore opposite the island. The out in 1989, demonstrated that in addition bow end of the vessel was recovered, and to the accelerated organic decay of sites on is now displayed in the National Museum drained land, submerged crannogs were also of Scotland in Edinburgh. A radiocarbon at risk of decay due to the infestation of determination for the log-boat was returned underwater plant and animal life caused by bc bc ad at 2501 ± 80 , calibrating at 355 to high levels of biological activity present in 125 (using OxCal v4.1.7, r.5), though the certain lochs (Barber & Crone 1993: 528). true date for the vessel is thought to be in the Loch Arthur was revisited in 2002, 2003 later part of this range, based the location of and monitored throughout 2004 to establish the dating sample with respect to the rings the condition and stability of the organic bc ad of the source tree: a date range c 150 – deposits surviving on the site. This was 200 seems most likely (Close-Brookes 1975; part of the overall aim of the South West Mowat 1996: 52, fig 18). The fragment of a Crannog Survey second phase: to establish dug-out canoe reported during the South West an effective system of monitoring the rate of Crannog Survey Phase 1 work at Loch Arthur organic decay on crannog sites in an effort to (Mowat 1996: 52) could not be re-located in provide accurate data on the sustainability of August 1992 during diving by Niall Gregory the crannog resource in the area (Lillie et al (see Canmore ID 65468l; Site Number 2003; 2004; 2008; Henderson 2004; 2007). NX96NW 1), and was also not seen by the As well as being part of the wider survey present authors during the 2002–4 seasons. project, the new work at Loch Arthur had Small-scale exploratory terrestrial the specific archaeological research aims excavations were carried out on the top of of clarifying the dating and structure of the the island in 1966–7, revealing the footings site. Williams’ medieval dating was based of drystone/clay-packed walls that the on the circumstantial finds of two bronze excavator interpreted as the stone undercroft tripod cauldrons from the loch, not the of a wooden-framed building (Williams crannog itself, while the position of the pile 1971: 123). Despite an absence of finds, sampled in 1989 was unknown. Although Williams suggested a 15th to 16th century the monitoring work is reviewed, this paper ad date for the crannog, based on two bronze focuses on the archaeological findings tripod cooking pots recovered from the loch from the site resulting from the most recent in the 19th century. campaigns of fieldwork. 106 | SOCIETY OF ANTIQUARIES OF SCOTLAND, 2011 THE SURVEY eroded flat to the loch bed (c 0.13–0.2m diameter). Rich organic deposits, consisting Diving in 2002 revealed that the majority of of bracken, twigs and comminuted plant Loch Arthur crannog lies underwater and is matter were exposed over the upper surface of much larger than the tree-covered island (on the lower mound. Most of the exposed timbers which mature oak and beech trees are growing) were covered in vegetation which appeared to visible from the shore. The island was seen to be accelerating erosion: the condition of the sit on top of a much larger mound which lay timbers varied from freshly exposed timber entirely underwater. The two features could bearing no vegetal growth, timbers covered be distinguished by their composition, the in vegetation, to timber in advanced stages of upper mound (the island) being built primarily decay. of large boulders within a well-developed At up to 3m visibility, the water quality in soil, and the lower, submerged, mound of Loch Arthur was amongst the best encountered timber (alder and oak), organic deposits and during the South West Crannog Survey, largely stones. Both horizontal and vertical timbers because the land around the loch is managed were visible throughout the lower mound, organically and is not therefore subject to the suggesting it was of artificial construction, heavy use of fertilisers, which could be seen to with the horizontal timbers arranged radially greatly increase biological activity adversely from the centre of the site. Around the eastern affecting the visibility in a number of other base of the mound c 30 piles were noted, lochs examined during the survey (Barber Sections at 50% scale, vert exag x2 0.0 20.0m N Dry Area D Contours at C 0.1m intervals 0.0 40.0ft z➣ B A D B -0.2 -0.1 -0.2 0.0 +0.4 -1.4 -0.3 +0.5 -1.7 -1.7 -1.5 -1.8 -1.9 -2.0 -0.5 -0.4 -1.6 -2.1 -0.6 +0.8 -2.2 -0.7 +0.9 -0.8 +1.0 Trench 3 -0.6 -0.9 -1.0 -0.8 -0.7 Trench 2 -0.6 -0.9 -1.0 A Trench 1 C Illus 2 Loch Arthur crannog – contour survey and location of trenches AN IRON AGE CRANNOG IN SOUTH-WEST SCOTLAND | 107 & Crone 1993: 528; Henderson et al 2003). southern edge of the submerged promontory Despite these more favourable conditions in in 2.5 to 3.5m of water and the other on the Loch Arthur, organic deposits and timbers on flatter top of the submerged mound in 0.75 to the site were actively being exposed and plant 1m of water (illus 2).