Aerial Archaeology in Wales
The Royal Commission's flying programme has three main aspects: exploratory work, the photography of sites and landscapes of national importance, and recording of industrial or architectural subjects. Exploratory reconnaissance is used to discover and record 'new' sites, some of which may only be seen from the air. In late spring or summer the buried ditches of plough-levelled sites may cause patterns of lush growth or 'cropmarks' in ripening arable fields or pasture; at the same time, buried stonework of walls and roads can cause crops to whither and parch out leaving lighter lines. In both these ways, cropmarks can show the position and layout of otherwise invisible archaeological sites. Very faint earthwork remains, often found in upland regions, can be equally difficult to see on the ground. When these sites are photographed in low winter or spring sunlight the effects of light and shadow, at times combined with a dusting of frost or wind-blown snow, can help to pick out indistinct outlines with striking clarity. In very dry summers, when conditions are exceptional, many hundreds of 'new' cropmark sites can be discovered in the space of just a few months, showing the fundamental contribution aerial photography can make to our understanding of the archaeology of Wales.
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