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Aerial Survey
Aerial photography has been used throughout the twentieth and into the twenty-first centuries to document the cultural landscapes of the world. National archaeological aerial survey undertaken by the Royal Commission across Wales continues this work. The Royal Commission has undertaken its own national programme of aerial survey in Wales since 1986. Flights are carried out in a 4-seater Cessna light aircraft from regional airfields at Haverfordwest, Welshpool and Caernarfon. The aerial reconnaissance programme encompasses all aspects of human activity across Wales, from prehistoric hillforts to modern architecture. During winter months upstanding earthwork monuments and upland landscapes can be recorded in low sunlight with little vegetation. During summer months prolonged droughts may reveal ‘cropmarks’ of buried archaeological sites in ripening arable crops or in parched grasslands. Other times of year, such as late spring and autumn, provide clear days with rich colours suitable for general photography of landscapes and townscapes. A further significant part of the flying programme is the annual recording for Cadw of over 600 Scheduled Ancient Monuments, protected sites of national importance.
Without the addition of aerial discoveries our understanding of the nature and extent of early settlement in Wales would be very limited. We can now appreciate that Wales was intensively farmed and settled from the Neolithic, 6,000 years ago. Thousands of significant ancient monuments have been ‘rediscovered’, from causewayed enclosures (the earliest built structures in Wales, dating to c.3500-4000 BC) and cursus monuments (ritual ‘avenues’ of the Neolithic) to Roman forts, early medieval burials and upland medieval farms. Parts of Wales, including the Vale of Glamorgan, the Welsh Borderlands, and the Carmarthen-Haverfordwest lowland corridor, have particularly rich buried landscapes in which cropmarks can be discovered during summer droughts.
Recording cropmarks and buried archaeology
The extent of the buried landscape of prehistoric settlements is often not appreciated. In the Borderlands and parts of Pembrokeshire aerial photography has shown that there was a similar density of prehistoric defended settlements to that of present-day farms. Countless archaeological monuments have been lost to agriculture, unwitting destruction and erosion in the centuries since they were first built. At ground level nothing may remain to show us the position of prehistoric farmsteads or Roman villas, but beneath the topsoil substantial remains may still survive of buried ditches, wall footings and other features.
In dry summers crops growing on well-drained lowland soils can reveal the shapes and positions of these buried remains through cropmarks. Cropmarks occur when plants growing over buried archaeological features, such as old ditches or post holes, grow taller, thicker and greener over the more fertile, damp soil and nutrients retained in the holes. Conversely, those growing over buried stonework and walling will quickly ripen and turn yellow in response to the shallow soil and lack of nutrients. These dramatic differences in growth revealed between the months of June and August are best seen from the air. Prolonged droughts, like those in 1976, 1995 or 2006, may reveal buried sites which have never previously shown. Subsequent years of crop rotation or summer rain may render the site invisible for a decade or more. Once the harvest begins the physical mark in the crop vanishes, so one is left with a four- or five-week window in which to capture the crucial image.
(Follow the link to the BBC website at the bottom of this page to view some good examples of crop marks from the air.)
Aerial recording of industrial and architectural sites
Buildings and industrial structures, along with townscapes, have always formed a key subject for the Royal Commission’s aerial photographers. One of the great strengths of the aerial perspective is its ability to bring coherence to complex patterns of buildings or structures which may be difficult, time-consuming or dangerous to record at ground level. Inaccessible parts of buildings such as roof-tops and parapets can be seen and recorded from the air, whilst a high view showing an overall plan and landscape context can have an immediacy and impact lacking in a ground photograph. Threatened buildings or working industrial complexes can also be difficult to access, making the aerial perspective valuable in illustrating restricted or dangerous areas. The flying programme routinely records structures which are also the subject of intensive ground surveys or photographic projects by Royal Commission staff. Since its inception in 1986, the RCAHMW flying programme has made enormous progress towards recording the industrial heritage of Wales, together with key examples of contemporary architecture. The collieries of South Wales were recorded in the early 1990s, particularly during 1992, in the face of their imminent demise. The images show the industry in transition, documented by Royal Commission industrial investigators before and after its closure.
Other notable examples of contemporary architecture and major redevelopments documented for posterity include the Inmos Building, Newport, The Great Glasshouse at the National Botanic Garden of Wales, Carmarthen, the Severn Bridge and Second Severn Crossing, the Millennium Stadium, Cardiff, and the massive wind turbines at Cefn Croes, Ceredigion, during installation and erection in 2004.