The Work

Fieldwork - 2004

Posted by steven on 02/04/2005 at 01:09 PM

UAMH AN ARD ACHADH (High Pasture Cave), Strath, Isle of Skye: Interim Report – November 2004.


In July 2003, a preliminary report was published regarding the recent archaeological discoveries and preliminary fieldwork undertaken at Uamh an Ard Achadh, Cave of the High Field or High Pasture Cave on the island of Skye (Birch et al, 2003).  This report provided a detailed background to the cave and its environs including the identification of stone-built structures in close proximity to the cave entrance.  Initial interpretations based on the discovery of these structures and material recovered from within the high-level passages of the cave suggested occupation and use of the site during the late Bronze Age and Iron Age periods.  Finally, the report discussed the continuing threat to the archaeological deposits within the cave and the need for further fieldwork at the site, to enable informed recommendations to be made regarding its future management.  In this brief report I will discuss recent developments at the High Pasture Cave site, including archaeological fieldwork carried out during 2004.


Analysis of the archaeological material recovered from High Pasture Cave during 2002 and 2003 indicated a domestic use for the site, while deposits of animal bone from specific locations within the cave was more difficult to interpret.  For example, although the animal bones had been recovered from heavily disturbed archaeological deposits it was still possible to identify concentrations of pig, cattle and red deer bone within Bone Passage.  The types and frequency of bone present within these deposits indicated that the carcasses of these animals had either arrived in the passage relatively intact, or that the animals had been butchered and the subsequent animal remains had been placed within specific locations within the cave.  Evidence for butchery of these animals was clear with regular cut marks, made by various types of metal implements, and the splitting open of long bones for marrow extraction.  One other important factor that came to light during the initial analysis of the animal bones was that the carcasses of pig had been butchered in a very different way to the cattle and red deer.  For example, the pig long bones had not been broken open to extract marrow, but remained remarkably intact, although cut marks were often present.

The high incidence of pig bones in the assemblage recovered from the deposits in the cave also contrasts considerably with other excavated archaeological sites in Scotland and within the wider context of the United Kingdom.  Most sites in the Hebrides in particular show pig to be a minor item of the diet during prehistory, with sheep and cattle being more prominent.  The so-called ‘high status’ sites of the period such as brochs and duns, have produced pig bone assemblages of 15 – 22% of the total recovered animal bone.  However, the High Pasture Cave assemblage produced in the region of 80 – 90% pig bone, prompting Peter Rowley-Conwy of the University of Durham to suggest that ‘feasting’ of some kind may have been carried out at the site.  This preliminary analysis was also borne out by the way in which the pig carcasses had been butchered in comparison to other species present on site, and from the analysis of similar deposits recovered from the Late Neolithic Enclosure of Durrington Walls in Wiltshire, England (Albarella & Serjeantson, 2002).

Figure 1.  The new site shed and entrance cover to High Pasture Cave - April 2004.

Viewed in conjunction with the structures of possible prehistoric date on the surface including a stone-built roundhouse, yards and smaller cell like buildings, and the presence of a large ‘U’-shaped structure of unknown function, the archaeological deposits in the cave presented several intriguing questions.  How was the cave utilised by the prehistoric inhabitants?  Were they merely using a hole in the ground has a place to dump unwanted rubbish, a process that has continued to the present day; or could the abandoned, high-level passage have been used as a natural souterrain, where people stored their produce and game in relatively stable temperatures throughout the year?  However, there was one other possible explanation for the use of the site, that of ritualistic behaviour. 

Figure 2.  The stone steps leading into the man-made chambers below Gurness Broch, Orkney.

Locations in the landscape such as springs, wells and deep natural shafts in the ground are known to have had a special significance with early Celtic societies, where access to the ‘Otherworld’ or ‘Underworld’ could be secured and offerings made to the water deities and ancestors.  And although sites such as these may be difficult to identify in the archaeological record, several sites have been recently identified that may have served such a function.  Several of the brochs discovered and excavated in Orkney, such as Gurness, have been found to have internal ‘wells’ or ‘cisterns’, many of which would have provided a poor and limited water supply.  Accessed by steep steps leading underground, archaeological deposits have been found in these so-called wells including the skeletons of red deer and other domestic animals.  However, the most significant site discovered to date in the British Isles has to be Mine Howe, also in Orkney.  From the surface the site now appears in the landscape as a low, grass-covered mound.  However, this man-made pile of earth surrounded by a deep rock-cut ditch of some proportions, contains a series of steps that takes one down steeply to small underground chambers and a well or cistern some 30 feet below ground, the whole structure built in dry stone walling and the chambers having corbelled roofs.  Anyone who has descended these steps to the ‘well’ below would soon realise how difficult it would be to extract water for normal domestic purposes, negotiating dark and slippery steps.  Therefore, we have several possible parallels in Scotland with which to compare our interpretations of the High Pasture Cave site. 

Figure 3.  Minehowe, Orkney - the impressive flight of steps leading into the ‘underworld’.  What was the purpose of these unusual monuments from the Iron Age?

Fieldwork – 2004

With the myriad of questions concerning the potential use of the High Pastures site and how it may have been incorporated within the wider prehistoric landscape in this area of Skye, we put forward a research design regarding further proposed archaeological fieldwork, including detailed survey and excavation.  And with successful bids for funding to Historic Scotland and the Society of Antiquaries of Scotland, we prepared for the 2004 season.

However, before proceeding with the proposed survey and excavation work, certain other housekeeping tasks had to be addressed including the construction of a new wooden surround and trap door for the cave entrance (to stop unwanted livestock) and a pulley system to haul buckets of spoil from below.  A dam was also constructed in the stream supplying the cave, to provide water for the wet-sieving equipment (the water being returned to the stream), and a site shed was erected in which we could store our equipment.

Figure 4.  Plan of the core structures on the surface above High Pasture Cave.  The cave passages running below the structures are shown in red - the hatched area indicating where the archaeological deposits were recovered from Bone Passage in 2002 and 2003

Therefore, with our equipment in place, we set about the archaeological fieldwork including a survey of the archaeological landscape surrounding the cave, a detailed planned survey of the surface structures in close proximity to the cave entrance, a detailed survey of the cave passages from the entrance down to Bone Passage (plan and profile) and the start of excavations in Bone Passage during the months of April and May.  The excavations started with the removal of disturbed deposits in Bone Passage, in order to prevent further damage to this delicate material, which also included the removal of boulders and smaller stone.  Because we would have to transport the stone some 50 metres through the main stream passage to the entrance, we decided to stack the larger material in Bone Passage.  However, the kibbles of mud and smaller stone removed using wooden trowels and spatulas (to prevent damage to archaeological material) had to be carried out to the surface, where they were processed through a series of wire meshes of varying size in the wet sieve (minimum mesh size 1.5mm).  The resulting material, including stone residues were then left to dry in air on absorbent tissue, after which they were initially sorted and separated into various finds trays.

Figure 5.  George Kozikowski operating the sieving equipment by the sink for the cave.

After removing the disturbed material we placed wooden runners along Bone Passage, where the archaeological deposits were most vulnerable, and nailed down wooden floorboards as walkways.  We then selected a location in the passage for Trench 1, our evaluation trench excavated this year, in order to examine the depth and preservation of the in-situ archaeological deposits.  Excavation then proceeded more slowly removing the thick mud deposits in 100mm spits, unless we uncovered more recognisable stratigraphic layers.  Because of the fragile nature of the archaeological material we removed the sediments in small lumps, after which they could be manipulated more easily on the surface and the finds removed.

A C14 date carried out on a juvenile pig lower mandible from the disturbed material (Context C001) provided a date of 2195±40BP.  Excavation of the trial trench in Bone Passage (Trench 1), measuring 1.8m x 1.0m, revealed a complex sequence of well-stratified deposits below C002, including a paved floor between C003 and C004.  The paving was formed from large granite cobbles, interspersed with fire-cracked stone, and deposits recovered from the surface included significant quantities of charcoal and charred cereal grains.  Animal bone and fish bone was also abundant from the contexts above the paved floor.  Below the paved floor the archaeological deposits became less distinct with the artefacts and charred grain etc. becoming less frequent, although animal bone and charcoal remained prolific.  The excavation of the trench continued down through lenses of occupation debris, some of which contained large clasts of stone more reminiscent of ‘dumped’ material, to a crushed limestone floor covered with fire-cracked stone, charcoal fragments and animal bone, some of which was heavily burnt (C009).  Recognisable here was the canine tooth of a brown bear, which along with a wolf canine from the deposits above provide evidence for some of the animal species that have now disappeared from Skye’s list of fauna.  We eventually reached the solid limestone floor of the passage at C011 – approximately 0.8 metres below the paved floor.  No C14 dates have yet been processed for the contexts and features recorded in Trench 1, although a large fragment of flat-rimmed, coarse pottery from C009 may be of Bronze Age date (mid second millennium to early first millennium BC - Cowie, pers comm.).

Figure 6.  Martin Wildgoose recording in Trench 1, Bone Passage.

Figure 7.  The periwinkle (shellfish) midden emerging from below a paving slab in Trench 1 (scale=0.25m).

Trench 1 has produced a wide range of samples, ecofacts and artefacts including large quantities of well-preserved animal bone, some of which display well-preserved butchery marks.  Land snails, marine molluscs, amphibian and reptile bones, and burnt hazelnut shell were also recovered through use of the wet-sieving apparatus.  Artefacts recovered from the excavations include antler and bone tools (including waste products), iron tools, stone tools (including small quantities of lithic material), pottery fragments, copper alloy fragments, rotary quern fragments and worked pumice.  Evidence for metalworking has also been recovered from the cave passage including iron slags, copper/bronze slags and ore-rich rock.  Of potential significance with regards to the ore-rich rock and metalworking debris is the discovery of a surface vein of magnetite containing a smaller vein of copper a few minutes walk from High Pasture Cave that may have been quarried in prehistory.  Samples taken from this site were compared with the ore-bearing rocks recovered from Trench 1 in Bone Passage, which confirmed the close similarities between the samples. 

We have also been fortunate in recruiting the services of cave morphologist Tim Lawson with the fieldwork in 2004.  Tim is looking in detail at the formation of the cave and the sediments it contains.  Samples have been removed for analysis and his colleague Ivan Young has produced a full set of digital images showing various elements relating to the morphology of High Pasture Cave and the surrounding landscape.  The results of the cave morphology survey will be crucial in guiding our interpretations on the archaeological deposits it contains, including how the sediments containing this material arrived in the system and how they may have been affected in the interim by natural agencies such as re-activation by water.  The survey also included use of the mole-phone and radiolocation equipment in order to fix positions within the cave system to features on the surface.  Of particular importance here is the possible location of a former entrance into Bone Passage that was used by the prehistoric inhabitants, but of which has subsequently been filled in.  We had already noticed the presence of a boulder choke at the end of Bone Passage, which seemed to be heading up towards the surface.  This possible entrance, whether a former sink for the stream feeding the cave, or a fissure where the cave passage roof has collapsed in, is situated within one of the structures on the surface.  There is however, no trace of this potential former entrance on the surface today.  The cave morphology survey will continue in 2005.

Figure 8.  A deposit of animal bone cemented together with calcite, recovered from Bone Passage.

Material recovered during our trial excavations in Bone Passage has also provided additional evidence to indicate that the prehistoric inhabitants of High Pastures were entering the cave.  Below one of the large paving slabs in Trench 1 we encountered a discrete periwinkle midden in an air-filled cavity, while two separate deposits of animal bone also suggest deliberate deposition in the cave.  Bones were uncovered from a setting of boulders against the wall of the passage, which had subsequently been covered with a natural calcite deposit.  After recovery and cleaning of the large assemblage of bones, which showed numerous cut marks and the breakage of long bones to extract marrow, it was found that the majority of the assemblage formed most of the skeletal elements of a calf (bovine).  The assemblage was so complete that fragments of broken long bones could be refitted, suggesting that the deposit had been placed in this location of the cave – possible as some form of votive offering. 

Figure 9.  Assemblage of animal bone recovered from the boulder setting in Bone Passage, comprising the butchered elements from a young calf (bovine).

Figure 10.  A selection of the refitted bone elements from the young calf (bovine), including long bones that have been smashed open to extract the marrow from within.

Post Excavation Analysis and Future Work

The fieldwork for the 2004 season has now entered the post-excavation phase, with the various finds, faunal remains, ecofacts, sediment and rock samples, despatched to various specialists throughout Scotland and England.  We have been fortunate in that many of the specialists are offering their services in-kind through the auspices of the respective universities.  Their reports will form a part of the much larger Data Structure Report and will hopefully assist us in securing further funding for fieldwork in 2005.  This will include further excavations in Bone Passage to enable us to assess the full extent of the archaeological deposits and to uncover further evidence of the paved floor and any other features that might be hidden below the deep sediments, while trial excavations will also proceed to examine the surface structures to assess their preservation and potential chronology with the archaeological material recovered from the cave passages below.  Trial excavation of the structures immediately above the cave passage will include the roundhouse, the ‘U’-shaped enclosure and a large grass-covered platform, in order to provide informed recommendations for the proposed 2006 fieldwork season.

Figure 11.  The vein of magnetite containing copper ore, which is located a short walk away from High Pasture Cave.

We have secured funding for the 2005 fieldwork season to undertake a geophysical survey of the High Pastures site to provide accurate data for the precise location and morphology of the former entrance into Bone Passage, and to indicate areas of activity in the vicinity of the structures on the surface.  On the successful completion of the survey we hope to excavate the former entrance and consolidate access, prior to commencing underground excavations in Bone Passage.  This will provide evidence to show how and when the entrance was closed, and will provide easier access to the excavations underground.  We presently have to bring excavated material through an active stream passage for around 60 metres to the wet sieving area on the surface, while larger stones and boulders have had to be stacked in the cave passage, which hinders movement in the cave.  The access will also allow better lighting equipment to be installed in the passage and CCTV cameras to allow viewing of the excavation work in progress through high-resolution monitors on the surface. 

From our preliminary investigations at the High Pastures site it would seem that the function of Bone Passage has changed through time and while it is possible that the cave may have been used as a natural feature in which to deposit domestic rubbish (midden material), it is also becoming increasingly obvious that people entered this dark and strange world for other reasons.  The construction of the paved floor and the discrete deposits of shellfish and animal remains, indicate an alternative use for the site.  Is it possible that this feature in the landscape provided a natural entrance into the ‘underworld’?  Whatever the reasons for the use of this fascinating site, the data gathered from our archaeological investigations will enhance our knowledge of Late Bronze Age and Iron Age communities in Skye, at a time when significant environmental change was taking place on a national scale.

Figure 12.  Plan and section drawings showing the archaeological features in Bone Passage, including Trench 1 and Feature F001 (where the deposit of animal bone was recovered). The floors are shown with red lines in the sections.

Dissemination of Information

We have now published a selection of preliminary reports regarding our fieldwork at the High Pasture Cave site, directed at local communities in Skye, the caving fraternity and for Historic Scotland and other sponsors that have supported our work.  A submission has been put forward for the 2004 issue of Discovery & Excavation Scotland, while a Data Structure Report relating to the fieldwork and post-excavation analysis of 2004/05 will be published and circulated during March 2005.

We have also delivered illustrated lectures on the High Pasture Cave Project at local level (local Historical Societies, Women’s Guilds and other institutions) and at the Highland Council Archaeology Seminar in Inverness, reaching a wide audience.  The Skye & Lochalsh Museums Officer, Mary Carmichael, also provided funds through Highland Council to host three open days at the site during Highland Archaeology Week.  On-site displays and guided tours of the surface features were available, while for the more adventurous guided tours were conducted into the cave passage containing the archaeological deposits.  The event was well attended and established the importance of our work at the local level, while visits from tourists on Skye at the time promoted our work to a national audience.

We hope to build on our work at High Pastures during 2005 with regards to interpretation and accessibility of the archaeology.  Additional open days are planned along with illustrated talks, while funding received from Leader+ and Highland Council will sponsor the construction and launch of a dedicated content-managed website for the on-going work.  This will include regularly updated fieldwork diaries, digital images of new finds and features and digitised video clips from underground CCTV equipment.  During open days the CCTV equipment will also allow images to be relayed directly to a high-resolution surface monitor, providing additional interpretive facilities for the visiting public.


We would like to acknowledge the assistance of our sponsors Historic Scotland, the Society of Antiquaries of Scotland, Highland Council, Skye & Lochalsh Enterprise - Leader+ and Jansvans of Portree, Skye; Fraser Hunter, Andrew Kitchener, Trevor Cowie and Alan Saville of the National Museums of Scotland; Noel Fojut, Patrick Ashmore and Ann MacSween of Historic Scotland; Kirsty Cameron and Hilary White of Highland Council Archaeology Services; Peter Rowley-Conwy and Carrie Drew of the University of Durham; Ruby Ceron-Carrasco and Anthony Newton of the University of Edinburgh; Mike Cressey of CFA Archaeology, Edinburgh; Chris Gleed-Owen of the Herpeotological Conservation Trust; Gerry McDonnell and Janet Montgomery of the University of Bradford; Jane Evans of the Isotope Geosciences Laboratory (NERC); Claire Pannell of the University of Glasgow; Tim Lawson, Ivan Young and Alan Jeffreys of the Grampian Speleological Group; and Mary Carmichael of Highland Council (Dualchas).  Finally, we wish to express our gratitude to Mr. Norman Stoddart of Kilbride House, Strath, for his permission to undertake the fieldwork at High Pasture Cave and for showing such an interest in this most intriguing site.


Birch, S.A. (2002) Uamh an Ard Achadh (High Pasture Cave): Deposits of Bone Breccia and Anthropological Indicators from a Limestone Cave on the Island of Skye.  G.S.G. Bulletin – Fourth Series, Vol.1, No.3 (October 2002), pp.12-27.

Birch, S.A., Wildgoose, M. & Kozikowski, G. (2003) Uamh an Ard Achadh (High Pasture Cave), Kilbride, Strath: Archaeological Deposits from a Limestone Cave on the Island of Skye.  A Preliminary Report.

Tolson, P. (1997) White Rose Pothole Club Journal.  Vol. 17, No.4, p.70.

Albarella, U. & Serjeantson, D. (2002) A passion for pork: meat consumption at the British Late Neolithic site of Durrington Walls.  In Miracle, P. & Milner, N. (eds) Consuming Passions and Patterns of Consumption, pp. 33-49.  Cambridge: MacDonald Institute of Archaeological Research.

Whetton, J.H. & Myers, J.O. (1951) Geophysical Survey of Magnetite Deposits in Strath, Isle of Skye.  Transactions of the Geological Society of Glasgow, 21/2, pp.263-77.

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