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Pen Y Cloddiau Hill Fort |
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Techniques employed: Magnetometry
Client: The Clwyd-Powys Archaeological Trust Stratascan were commissioned by the Clwyd-Powys Archaeological Trust to undertake a geophysical survey of an area of the Pen y Cloddiau Hillfort. This survey forms part of an archaeological investigation after an accidental heather burn in 2003. The Clwyd-Powys Archaeological Trust have also carried out a topographic survey which has been used in the base mapping for this report.The work is being carried out on behalf of Denbighshire County Council who are in the process of developing a wider project involving the management, study and interpretation of the Hillforts and Heather in the Clwydian Range Area of Outstanding Natural Beauty. Pen y Cloddiau is the largest hillfort in the Clwydian Range with a total area of 21ha enclosed within the ramparts.This Scheduled Ancient Monument has not been subject to any known archaeological excavation and very little is known about the site.The site is extensively covered in heather which is generally unmanaged and masks any archaeology.In March 2003 7ha of the interior was affected by an accidental heather burn and study of subsequent aerial photography suggests the possible existence of hut circle platforms within the burnt area |
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The magnetic survey was carried out using a dual sensor Grad601-2 Magnetic Gradiometer manufactured by Bartington Instruments Ltd. The instrument consists of two fluxgates very accurately aligned to nullify the effects of the Earth's magnetic field. Readings relate to the difference in localised magnetic anomalies compared with the general magnetic background. The Grad601-2 consists of two high stability fluxgate gradiometers suspended on a single frame. Each sensor has a 1m separation between the sensing elements giving a strong response to deep anomalies. |
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The resistance meter used was an RM15 manufactured by Geoscan Research incorporating a mobile Twin Probe Array. The Twin Probes are separated by 0.5m and the associated remote probes were positioned approximately 15m outside the grid. The instrument uses an automatic data logger, which permits the data to be recorded as the survey progresses for later downloading to a computer for processing and presentation. The small area of resistivity survey showed areas of high and low resistance. Because of the small survey area it is difficult to be certain if these are features with an archaeological origin or if they relate to geology or pedology. Field observations revealed that over much of the site the natural bedrock is close to the surface and that soil depths and peat build up are variable across the site. Potentially further resistance survey over a larger area using the double twin probe array may well locate other anomalies and will allow for greater understanding and interpretation of their distribution and relationship. The magnetometry survey showed that the area has not been subject to modern disturbance or agricultural activity and that any anomalies located were of a very low magnitude. Although the origin of the low magnitude responses are uncertain, the results suggest the possibility of features with archaeological potential. |
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| REPRODUCED BY COURTESY OF THE CLYWD-POWYS ARCHAEOLOGICAL TRUST | ||
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