The U.K. is experiencing its driest summer in fifty-seven years. It’s not been great. A British summer is usually a doubtful, fleeting thing. Sunshine and heat arrive in bursts from June until September, as if you were walking down a green-shaded path with occasional breaks in the canopy. When the sun does come out—during Wimbledon, say, or for a spell in August—British people go reliably mad, take their tops off, and barbecue frantically for a few days, until the skies cloud over again. This year hasn’t been like that. The country warmed up in June and has baked steadily since, like an oven that has reached its cooking temperature. Between late June and early July, Britain endured sixteen consecutive days when the temperature hit eighty-two degrees. Last month, eastern England had four per cent of its usual rainfall. In London, a city not known for its air-conditioning, the parks turned brown, the road surfaces went mushy in the afternoon ferment, and the nights became unbearably still. Foul, sweet smells hung in the air. This unusual British summer has been accompanied by terrible wildfires in California and Greece, a balmy Arctic, and dozens of heat-related deaths in Japan. Even when it finally rained, late last week, it didn’t bring much relief. Last Friday, Britain was hit by an estimated hundred and thirty thousand lightning bolts—enough electricity to boil a billion cups of tea—as summer storms played havoc with the nation’s roads, railways, and airports. August is going to be even hotter.
But at least the archeologists are happy. “It’s a bit like kids in a candy shop,” Robert Bewley, an aerial archeologist at the University of Oxford, told me, a few days ago. The freak conditions have made this summer one of the best in living memory for what archeologists call “parch marks”—ghostly, pale outlines of vanished castles, settlements, and burial sites that materialize on the land when it dries out and grass and crops die off. In recent weeks, archeologists in light aircraft, hobbyists with drones, and even people walking through their local parks have discovered Iron Age farms in South Wales, a Roman road passing near Basingstoke, burial mounds in Ireland, and the outline of Second World War bomb shelters on the lawns of Cambridge. Seen from above, the parch marks have a magical quality, as if a giant had doodled them from memory, but they are also disconcertingly real. They are only there because something else was.
Parch marks—and their less dramatic form, crop marks—are fairly common clues for archeologists who are working in places with long, dense histories of human habitation. (Bewley also works in North Africa and the Middle East.) The buried remains of Roman foundations or medieval walls will cause “negative” crop marks in a field of grass or wheat, because the roots of the plants on top of the ruins have less soil to work with—a phenomenon that becomes more noticeable when water is in short supply. The opposite is also true: filled-in ditches and moats, with their deeper soil, can lead to taller, greener plants and “positive” crop marks. The first aerial image to really excite British archeologists was taken in 1906, when British Army officers photographed Stonehenge from a balloon and noticed a darker ring of grass around the stones—the trace of an ancient ditch. “You go to a site to photograph what you know is there, and then you see something next to it,” Bewley told me. “That happens virtually every time we go flying.”