EXPERT aerial reconnaissance teams in Swindon and York are taking advantage of the summer's unusually hot, dry weather to learn more about the ancient history visible in our landscape.

The dry weather is a great time for aerial archaeologists to 'see beneath the soil' as crop marks left by ancient buildings and structures are better defined when the soil has a lower moisture content so experts from the Historic England, based in Swindon, are working as fast as possible to take aerial photographs of the land - and they hope to make some exciting finds in the locality before the weather changes.

Helen Winton, Aerial Investigation and Mapping Manager at Historic England, said:

"Cropmarks are differences in the colour and / or height of a crop. The variation in growth is caused by what is present below the plough-soil. The dry soil conditions mean that cropmarks are more likely to form because the roots of the crops growing over buried archaeological remains have access to different levels of moisture to those in the rest of the field. The aerial view means that we can see the patterns of buried ditches or walls that once defined settlements, field boundaries or funerary monuments.

"The main benefit is in the new discoveries that allow us to identify and understand the extent and form of otherwise hidden archaeological remains. This helps with archaeological research so that we can determine the significance of the buried remains and if necessary make decisions about protecting them from development or intensive agriculture. A bonus is that cropmarks also confirm that previously known sites are still preserved beneath the soil as some only show in very dry conditions – the lack of a cropmark does not mean the archaeology has gone."

She said the Historic England teams were working hard to cover as much of the country as possible.

"Using a light aircraft, we can quickly assess conditions over very large areas. Where we have them, we use archaeological maps, compiled from aerial photographs in our archive, to check if a site is known already.

"It is too soon to say how many new discoveries we have made as we have to process the digital photographs and double check that the sites aren’t already recorded elsewhere."

She explained: "This is the first potential bumper year we have had in what feels like a long time. The recent changeable and quite wet weather has not been great for cropmarks so it is very exciting to have hot weather for this long. 2011 was the last time we had an exceptional year when we discovered over 1,500 sites, most on the claylands of eastern England. Fingers crossed for the same this year."