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Moel y Gaer Hillfort, Llantysilio, Denbighshire

Archaeological excavations 2010

A small-scale excavation was conducted by CPAT on behalf of Denbighshire Countryside Service to investigate the interior of Moel y Gaer Hillfort, near Llantysilio. The work forms part of the Heather and Hillforts project, with funding in part from the Heritage Lottery Fund.

Moel y Gaer hillfort is located on the ridge of Llantysilio Mountain, occupying a minor summit (SJ 16695 46376) between the more prominent summits of Moel Morfydd and Moel Gamelin.

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Right: View of Moel y Gaer from the north-west. The extent of erosion from off-road vehicles is clearly illustrated CPAT 06-c-0373

The hillfort is surrounded by a single rampart enclosing an area of approximately 0.95 ha. The rampart is most prominent on the northern and eastern sides of the hillfort where an external ditch is also evident. There is a single entrance on the eastern side that has an inturned corridor. Although the fort occupies a minor summit it has a commanding view over an ancient trackway that is now part of the Clwydian Way. Located below and to the north of the ramparts, the trackway traverses the saddle east to west between Moel y Gaer and Moel y Gamelin. The location of the fort effectively allows it to control one of the ancient routes from the Dee Valley across Llantysilio Mountain, ultimately leading to the Vale of Clwyd. The antiquity of the route is attested by presence of multiple holloways which demonstrate how the trackway has shifted its position over time.

The fragility of the site was highlighted by the presence of an illegal off-road track located to the west of the site and the use of illegal vehicles on the footpath which goes through the centre of the fort. Because of the potential of damage to the interior of the fort, the excavation was designed to investigate an area where the geophysical survey had identified a range of features and to assess at what depth below the present horizon these archaeological deposits occur.

As part of the Heather and Hillforts project a condition survey of the hillfort was conducted by CPAT in 2004, followed by detailed topographical and geophysical surveys, both conducted by Engineering Archaeology Services (EAS) in 2006 and 2009 respectively. These surveys identified around twenty possible roundhouses, eleven of which had earthwork remains in the form of levelled platforms. The geophysical survey also identified possible internal tracks and two potential rectangular structures (Brooks and Laws 2009).


Right: Plan of Moel y Gaer hillfort showing the location of the 2010 excavation

Prior to the present project there had been no previous archaeological excavations on the site and so the nature, depth and extent of any significant archaeological deposits were unknown. The condition survey of 2004 highlighted the vulnerability of the site as a result of illegal off-road use, as well as the presence of a footpath which runs through the entrance and across the western rampart. The potential for further damage to the interior of the hillfort led to the present evaluation which was designed to investigate an area where the geophysical survey had identified a range of features, including two roundhouses and a possible rectangular structure. The objective was to assess the nature, significance and vulnerability of any surviving archaeological deposits.

The excavations were undertaken over a two-week period in late September and early October 2010 with the assistance of up to seven local volunteers, some of whom were from the Heather and Hillforts archaeology group, coordinated by Miss Samantha Williams, the Hillforts Conservation Officer


The trench measured 20m by 3m and was orientated north-north-east by south-south-west, positioned on a north-west facing plateau within the interior of the fort. The trench was sited in such a way as to investigate an area where the geophysical survey had identified a range of intersecting features including two round-huts, a possible rectangular structure and a trackway. If we could establish the relationship between these features then we would possibly have the basis for outlining different phases of occupation on the site, whether they were, for example, later Bronze Age, Iron Age or even Early Medieval. Samples for potential palaeoenvironmental analysis and radiocarbon dating were taken from key features which, together with stratigraphic evidence, could help with the potential phasing of the site

The initial overburden, consisting of heather scrub and an underlying dark brown gritty silt-clay and no more than 80mm thick, was removed by hand and stored adjacent to the trench. The removal of an underlying layer revealed the contour of a raised platform at the southern end of the trench. Other shallow features, indicated by areas of a dark peaty fill, were also noted together with a deliberately placed stone slab and several lines of stones set on edge.

As the excavation proceeded it became apparent that the site could be separated into two, allowing each area to be worked independently of the other, whilst noting any key stratagraphic relationships between them. To the north, the lower terrace was characterised by occupation levels defined by layers of soil deposits of trampled, turfy silty clays with charcoal flecking. As these were meticulously cleaned numerous underlying features were revealed, some of which suggested the outline of an early roundhouse. To the south, the raised terrace had begun to resemble the central area of a hut platform, defined by a series of consecutive construction layers of shattered shale, silty clay, and lenses of peat formation.

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Right: Removal of initial overburden on the lower terrace. Moel y Gamelin in the backgound CPAT 3175-0005

On the lower terrace, the initial objective was to remove the deposits to a level where we could be sure that the layers were consistent and, from a sampling point of view, undisturbed across the extent of the trench. At no point during this exercise was the natural undisturbed bedrock encountered. This meant that the shattered stones on edge appearing in either curvilinear lines or sub-circular peat stained areas could potentially be the first indication of archaeological features. Where time allowed, sections were excavated through some of these features and this revealed the survival of earlier underlying occupation deposits.

The most prominent feature was a curving gully which defined the area of a roundhouse about 7m in diameter, although only the north and south sides fell within the excavation. The gully contained up to three fills, all of which contained edge-set stones. Assuming we had now identified an early roundhouse, sealed in part along the southern edge by the later hut platform, we could now begin to investigate the relative phasing of the site.

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Left: The drip gully surrounding the earlier roundhouse, viewed from the north-east CPAT 3175-0098

Within the interior of the roundhouse several features appeared to be contemporary with its use. An irregular, butt-ended gully, aligned east-south-east to west-north-west, was only 20mm deep and varied from almost 1.0m in width to 0.4m at the limit of excavation. The fill consisted of a dark, silty peat containing charcoal. Given its position and orientation it is possible that this represents an internal division within the roundhouse. A second feature, extending beyond the limits of excavation, was a pit or butt-ended gully

Between these two features was what may be a post-pad, consisting of an earth-fast, flat stone on top of which several other flat stones had been laid (Fig. 10). The excavations revealed no evidence for any further post-settings, although it is possible that post-holes were located beyond the excavated area. There was also no evidence for an entrance, although given the prevailing winds this is likely to have been on the unexcavated eastern side of the roundhouse.

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Right: The earlier roundhouse viewed from the north CPAT 3175-0096

The only artefact from the excavations was recovered from an occupation deposit beyond the northern perimeter of the roundhouse. The item, believed to be either a hammer-stone or rubbing stone, had been fashioned from smooth, fine-grained sandstone. This did not match the local geology (which is predominantly shale) and thus it was concluded that the artefact was intrusive to the site. The stone, measuring 25mm thick, 110mm long and 70mm wide, is smooth and rounded to the touch and has some evidence of 'peck' marking at both ends. Central to the stone is a worn depression that runs diagonally across the natural grain.

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Left:Visitors on one of the guided walks organised by Denbighshire Countryside Service being shown around the site by CPAT's Ian Grant CPAT 3175-0035

The northern side of the gully surrounding the roundhouse was sealed beneath the stony make-up forming a raised platform for the construction of second structure, which was also around 7m in diameter. The southern side of the platform had been cut into the underlying bedrock, creating a rock-cut scarp approximately 0.3m high, the spoil from which would have been utilised in the primary construction of the platform. At the base of the scarp was a narrow, curving gully, 0.1m wide and 0.1m deep, which had also been cut into the bedrock.

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Right: The rock-cut gully at the rear of the later roundhouse platform CPAT 3175-0100

The primary construction layer for the roundhouse platform was a spread of stone, consisting of fragmented shale. The material was only evident to the rear of the platform, the central area being predominantly a deposit of shale chippings set in a matrix of greasy grey silt clay. This was in-turn sealed by a layer of firm, trampled chippings set in reddish-brown silt clay. All of the layers contained spreads of charcoal flecking, attesting to evidence of occupation. A sondage excavated across the edge of the platform demonstrated that it sealed an earlier occupation layer. It was during this point of the excavation that our understanding of the relationship between the two phases of the site was re-enforced. The make-up for the platform clearly sealed another deposit which in turn covered the drip gully of the earlier roundhouse.

To the rear of the platform a thin lens of peaty soil covered the stoney layers within the roundhouse, perhaps indicating a period of disuse. This was sealed by a final occupation layer consisting of trampled, fragmented shale and stone chippings within a matrix of buff, gleyed, silty-clay with charcoal flecking. At the northern end of the platform a deposit of compacted shale and peat formed the final layer associated with the platform, just extending into the interior of the earlier, northern roundhouse.

Also noted at this level was a mottled, clay-rich deposit with charcoal flecking forming a 1.5m-wide band which respected the rock-cut edge on the southern side of the platform. The composition of the deposit was unusual as there is no naturally occurring clay within the immediate area. Speculatively, this could represent wattle and daub which had decayed in situ. These later deposits post-date the roundhouse platform and it is possible that they are associated with the reuse of the platform, perhaps as part of a later structure for which no definite structural elements could be recognised.


It is clear from the excavations that there is good in-situ preservation of significant archaeological deposits within the interior of Moel y Gaer hillfort. However, the shallow depth of the overburden across the site, specifically on the lower terrace where the combined depth of the heather, topsoil and late peat formation is only 0.15m, is testament to the fragile nature of the surviving archaeological resource.

The excavations revealed evidence for several phases of activity, including at least two roundhouses, each around 7m in diameter, which had been built on top of earlier occupation layers which were not investigated during the excavation. The earlier roundhouse was defined by a curving drip gully, with no sign of an entrance, although this is perhaps likely to have been on the more sheltered eastern side, outside the excavated area. Internally, an irregular gully may indicate the position of a partition, while a possible post-pad was the only evidence for the structure of the roundhouse.

In a later phase of activity another roundhouse was constructed immediately to the south, built on a platform which had been cut into the bedrock on the south side and levelled by deposits of stony material to the north, sealing part of the gully surrounding the earlier structure. Again, there was no indication of an entrance or any evidence for the construction of the roundhouse, apart from a cut-rock drip gully on the south side. There was some evidence to suggest a period of disuse, in the form of a thin peat lens, followed by a later phase of occupation on the same platform which could have incorporated wattle-and-daub walling, although with no other indication for a structure.

Finally, although the geophysical survey suggested the possibility of a rectangular building orientated east to west across the axis of the excavated area, no evidence for such a building was uncovered during the excavations. It is possible, however, that this could be associated with an earlier phase of activity, sealed beneath a occupation layers underlying the earliest roundhouse.

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