FOR archaeologists, the UK’s current heatwave is more than just an excuse to kick back and soak up some rays. When the ground is baked by days of sun, markings that indicate the location of ancient settlements begin to emerge in the parched terrain.
In the picture below, the outlines of a medieval hilltop fort known as Castell Llwyn Gwinau are clearly visible in a field near the town of Tregaron in Wales.
The green circles and lines are created because ancient peoples dug deep trenches to fortify their settlements. Although now filled in, these still act as moisture traps and, in dry conditions, the crops above them become lusher and greener than the surrounding area. The shapes of such forts and farming settlements, some from the Roman and Iron Age periods, are then revealed from the air.
Much of the northern hemisphere has been roasting in sustained high temperatures, with records tumbling around the world (see “Record heatwaves are here to stay – welcome to our warming world” for more on why it is happening).
This article appeared in print under the headline “Ancient forts emerge in the heat”
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