A heatwave has revealed fleeting traces of early settlements to historians taking a bird's eye view of Scotland. The conditions this summer have proved ideal for aerial archaeologists who document the buried sites, which appear in ripening crops or scorched grass. The Royal Commission on the Ancient and Historical Monuments of Scotland said it was one of the best in its 30 years. Discoveries have included various prehistoric settlements.
     Dave Cowley, the aerial survey manager at the RCAHMS, said: "Bits of the Borders, some of the Cheviot foothills, parts of Fife and the Moray Plain have produced previously unknown sites. Town Yetholm through to Morebattle have been producing material, which is parched out in grass. We have seen various types of prehistoric settlements usually as circular or rectangular enclosures and burial sites."
     Archaeological sites become visible most commonly on farmland during the summer months. "In the lowlands, in particular, ancient sites and monuments have been levelled out by agriculture, and while these sites are not usually detectable, during hot spells they can become visible from the air," says Cowley. "When cereal crops are planted on the top of these sites, different rates of growth and ripening can cause buried features to reveal themselves. Crops will often grow taller and greener above ancient ditches because extra water and nutrients are found there, while buried walls or paths can deprive plants of nutrients, showing up as yellow patches, known as parching."
     Because of the farming calendar, archaeologists face a race against time to get all the information catalogued. "We have to conduct all our investigations [by] August, as we have to photograph as many sites as possible once the crops have come up, but before they are harvested," says Cowley. "The sites are no longer visible and won't be until the next spell of hot weather".
     The RCAHMS aerial survey has undertaken about 1,000 flights, using a four-seater Cessna aircraft from its base in Edinburgh, and it has produced more than 100,000 images of the country since 1976. "Sites become visible every summer to varying degrees, but for the past few years we have had fairly poor summers," says Cowley. "This year, ideal conditions meant that sites became visible of which we had been completely unaware, including a prehistoric settlement near Melrose, and an Iron Age enclosure at Letham. In addition, existing sites have appeared in much greater detail.
     "The information will now have to be analysed thoroughly and will be made available to the public on the Canmore Database," added Cowley. "This is what gives future generations access to information and records on every aspect of our built environment. We can only speculate at the moment as to what this year's findings may tell us, but one key thing is that we have discovered more Iron Age locations."
     
Sources: BBC News (22 August 2006), The Scotsman (23 August 2006)