Beacon Hill, Radnorshire - Royal Commission on the Ancient and ...

RCAHM Wales Uplands Initiative – <strong>Beacon</strong> <strong>Hill</strong>3.1 Use of aerial mappingFigure 16. Quarry on <strong>Beacon</strong> <strong>Hill</strong> (nprn 244211).Mapping of archaeological features from aerial photographs was carried out by RCAHMWales prior to the commencement of the field project. The results were incorporated on todigital maps that were used in the field for identification and verification. Approximately50% of the total number of sites identified in the field had been mapped. Where largefeatures had been identified the map provided a useful overview of features, particularlyfield boundaries. The number of sites identified on the maps that could not be verified inthe field as archaeological features was small. This included some trackways that wereinterpreted in the field as sheep tracks or were not visible on the ground. By contrast, manyof the trackways recorded were not mapped.Of 28 areas of ridge and furrow identified from aerial photographs, 20 were identified onthe ground in some form. A further 18 areas of ridge and furrow were identified that hadnot been mapped. In some cases discrepancies might have been due to the recent densebracken cover that inhibits identification of features that make only a slight impression onthe ground. In some cases the direction of the ridges shown on the map was across theslope, which is not the traditional direction for ploughing on slopes, and so the aerialmapping might have interpreted the parallel lines created by bracken cutting. Bracken wascut to provide bedding for stock and remains one of the rights of commoners on <strong>Beacon</strong><strong>Hill</strong>.In some cases aerial mapping identified a large area of cultivation ridges (nprn 244021,244080, 244115) where only discrete patches could be identified on the ground. Bycontrast, in other cases (nprn 244046, 244190) the cultivation ridges were found to extendbeyond the limits defined by the map.Only two platforms were identified from aerial photographs, whereas a large number werefound in the field; and four of the nine pillow mounds were mapped. Nearly all of the fieldsystems and field banks were identified on the maps, although with notable lacunae,16