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The real kind of crop circles…er…rectangles.

Photos: A heat wave in the UK is revealing evidence of ancient structures

Johnny Simon
By Johnny Simon

Deputy Photo Editor

Hot weather across Britain, it turns out, is a great time for archeologists to take to the sky.

Through aerial archeological surveys, hot and dry conditions have made it possible to see “cropmarks,” or shapes denoting ancient structures, from above. Cropmarks are darker areas of vegetation where fortification ditches from past settlements once were. Even though they were filled in many years ago, the topsoil reaches down deeper than the rest of the surrounding farmland. When hot and dry weather strikes, the vegetation above the filled in ditches has more nutrients and moisture, leaving it slightly greener than its neighbors.

Aerial photos provided by the Royal Commission on the Ancient and Historical Monuments of Wales show the cropmarks appearing over many well-known Welsh archeological sites.

Toby Driver/RCAHMW
Cropmarks near Langstone, Newport, Wales.
Toby Driver/RCAHMW
A Roman site near Magor, south Wales.
Toby Driver/RCAHMW
A view of a Roman fort in Pennlwyn, Wales.
Toby Driver/RCAHMW
Trewen Caerwent
Toby Driver/RCAHMW
Cross Oak Hillfort, Welsh Iron Age site.
Toby Driver/RCAHMW
A view of Castell Llwyn Gwinau, a Welsh archaeological site.
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