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Dig Diary, 2008

Prehistoric Axe Factory near Hyssington, in Powys
Archaeological Survey and Excavation 2007-8


Introduction

During September 2007 a programme of survey and trial excavation was undertaken by CPAT in an attempt to confirm the source of the Group XII Bronze Age battle axes and axe hammers which have been found in Wales and the Marches. The axes are made from a distinct rock type known as picrite which is has a very limited distribution, with one of the known outcrops being a small hill just to the north-west of the village of Hyssington in eastern Montgomeryshire.

Cwm Mawr

Right: Aerial view of the site - the picrite outcrop occupies the hill in the foreground, with Hyssington towards the top left. Photo CPAT 00-c-0037

This area was first suggested as a potential source for the axes following a study in the 1950s, the results of which were published in a paper by Shotton, Chitty and Seaby in the Proceedings of the Prehistoric Society in 1951. They identified a number of likely rock sources around the hill, including a small quarry, and concluded that the site 'clearly calls for excavation'. Since the 1950s other products from the axe factory have been found over a wide distribution and a number of other local features such as picrite outcrops, boulders, and small quarries have been recorded.

A second season of excavation was undertaken between 15 September and 3 October 2008, in conjunction with Amgueddfa Cymru National Museum Wales. CPAT's funding for both seasons has been provided Cadw.

Field Survey

Cwm Mawr axe hammer and battle axe
(and a 50 pence piece)

Cwm Mawr

A programme of systematic field survey was undertaken covering the area of the picrite outcrop (c. 30ha) to identify and record those sites already thought to be potentially associated with the axe factory, as well as prospecting for further potential sites. At an early stage it became clear that not all of the potential sites were outcrops of picrite, as some small-scale quarries had also been recorded on an adjacent hill where the geology is dolorite. However, several small quarries and outcrops were confirmed within the area where picrite had been identified by the Geological Survey. Each of the sites was assessed and two areas were then selected for geophysical survey.

Geophysical Survey

Geophysics

Carrying out the magnetometer survey within the quarry on the south-east side of the hill

A limited programme of magnetometer survey was undertaken in 2007 adjacent to two small quarries, one on the north side of the hill, and the other on the south-east side. The gradiometer has an on-board data logging device which enables readings to be taken at specific time intervals. These readings can then be correlated with geographical locations. Readings were taken along parallel traverses of a 20m by 20m grid, with a traverse interval of 1m. The speed of each traverse was controlled such that readings will be taken every 0.5m, thereby giving a total number of 800 readings per full grid. The survey grids were laid out and then located in relation to nearby field boundaries by total station surveying, using a digital laser theodolite.

It had been hoped that the surveys might provide some indication of occupation and activity, possibly identifying hearths or areas where the rock had been quarried using a technique known as 'fire-setting', where an outcrop is heated and then rapidly cooled with water, causing cracking. However, neither of the surveys produced any evidence which could help to target trial trenching.

Trial Excavations

outcrop

Right: Outcrop of picrite exploited by one of the small quarry scoops. Photo CPAT 2485-044

A programme of small-scale, hand-excavated trial trenching was carried out in September 2007 to investigate three sites on the south-eastern side of the hill, including the small quarry which had been highlighted in the 1950s as a potential stone source. The quarry measures 11m by 8m overall and has a number of picrite boulders visible in the base, possibly resulting from later field clearance. A single trench was opened within the quarry which revealed a mass of voided stone filling the quarry base. It soon became clear, however, that the task in hand was beyond the limited resources available at this time and work concentrated instead on two small features 35m to the south-east, which had the appearance of quarry scoops.

In both cases an outcrop of picrite was visible, below which was a small, oval platform, the appearance of which suggested that spoil could have been removed from the outcrop and deposited downslope. The removal of the topsoil appeared to confirm the initial impressions in both trenches, after which excavations only proceeded in one trench. This revealed an outcrop 0.9m high, which had been fractured as a result of natural weathering and this appeared to have been exploited to extract stone. It is possible that the natural cracks in the rock had been expanded using wedges to separate large blocks, which had been removed. In all, the face of the small outcrop may have been moved back by at least 2m as a result of quarrying. It was interesting to note that there were a number of potentially axe-sized rocks which had been discarded in the general spoil.

The 2008 excavations concentrated on re-opening and expanding the previous year's trench across the small quarry. The quarry had been partly backfilled by a dump of large boulders, two of which were too large to move. Two iron shovels were found in association with the boulders, and further nails and iron objects were found in a deposit of freshly-broken picrite at the lowest level of the quarry, clearly demonstrating that the quarry was of no great antiquity.


picrite and axe

Left: Comaprison of a weathered axe hammer and a freshly-broken piece of picrite. Photo CPAT 2648-157

A further three trenches were excavated, two adjacent to the quarry, and the other across one of the many small quarry scoops first identified and investigated in 2007. Each trench produced further evidence for small-scale stone extraction, exploiting the natural fissuring in the rock. However, the excavations failed to produce any artefacts or other dateable material.

One of the things which has been most apparent is the dramatic difference between the present-day appearance of the picrite axes and how they would have looked when they were first fashioned. The centuries of weathering has produced a rather dull, orange-brown surface, whereas the freshly-hewn picrite is a vibrant blue-green.

Carved Stones

carving

Right: One of the carved stones recovered during the 2008 excavations. Photo NMW.

The excavations revealed several stones bearing numerous incised lines. Unfortunately, none of the examples were well stratified. The designs, chiefly cross-hatched, resemble those found at Neolithic sites such as Ness of Brodgar, Quoyness and Skara Brae on Orkney and at Millin Bay, Co Down in Ireland. Although the designs on the stones at Hyssington cannot be directly dated, detailed study of those on the sandstone example show that they were made by pecking rather than incising, suggesting a prehistoric rather than a later date.

Conclusions

Although the investigations have yet to confirm the site of prehistoric stone extraction, the results from the trial excavations have clearly demonstrated that picrite was being quarried across an area of around 65 by 20m. Although the field evidence suggests that working was restricted to small-scale extraction sites, possibly suggesting a rather piece-meal approach, there is no doubt that a significant quantity of picrite could have been removed. It is not possible, however, to determine the level of the original land surface, although it may be presumed that outcrops of picrite were perhaps rather more visible than at present. Unfortunately, the excavations failed to recover any artefactual evidence to indicate the likely date of these workings.

2008 excavation

Left: The 2008 excavations within the quarry. Photo CPAT 2648-125

Despite the lack of direct evidence the area of the excavations, on the south-eastern side of the hill, still appears to represent the most likely source of stone for the picrite axes. The lack of artefactual evidence is in part due to the nature of the picrite, which is likely to have been extracted using no more than wooden wedges and worked using a percussive technique which would not result in the working flakes typical of other axe factories. In addition, it is quite conceivable that the stone may have been worked at a separate location which may only come to light through the chance discovery of rough-outs and wasters.

The unexpected discovery of a number of stone carvings in close proximity to areas of extraction has given new significance to site. The decoration, which consists of numerous parallel and crossing lines, is similar to examples found in Neolithic contexts in Scotland and Ireland. Although none of the discoveries were from well-stratified contexts, and cannot therefore be confidently associated with quarrying activities, their presence does confirm significant prehistoric activity on the south-east side of the hill.

No further fieldwork is envisaged as part of the present project and is must therefore be hoped that future discoveries will eventually confirm the site of prehistoric workings.

Follow this link to see reports about the exploration of the Hyssington axe factory in the 2008 dig diary.


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