Drought Reveals Traces of Ancient Roman Structures in Wales

Archaeologists used aerial photographs to discover previously unknown forts and roads in water-starved fields across the country

Carrow Hill Roman fort
The hot, dry summer of 2018 revealed the long-lost outlines of Roman forts and roads in Wales. This photo shows a Roman fort discovered near Carrow Hill. Crown Copyright / RCAHMW

Two years ago, the United Kingdom experienced an unusually hot summer. Roads melted, fires broke out and the typically verdant English countryside turned brown due to drought.

For archaeologists, the dry weather came with a silver lining: namely, circles, rectangles and other assorted shapes that started appearing in parched fields, their outlines sketched in straw yellows, withered browns and lush greens.

As Toby Driver, an aerial archaeologist with the Royal Commission on the Ancient and Historical Monuments of Wales (RCAHMW), explained to NPR’s Renee Montagne in July 2018, the ghostly contours emerging from the landscape were traces of Britain’s past.

“It’s a bit like an X-ray of the field is revealed,” he said.

Ancient structures such as roads, trenches and buildings left imprints that affect how soil drains today, creating uneven patterns of moisture that can keep a patch of grass green even as neighboring vegetation loses color.

During the scorching summer of 2018, Driver and his colleagues took to the skies to document as many of these crop markings as they could, taking around 5,700 photographs over seven weeks, reported BBC News at the time. Their efforts revealed more than 200 new archaeological sites across Wales.

Roman road aerial photo
Outline of a Roman road in the Teifi valley near Lampeter Crown-Copyright / RCAHMW

Now, many of these discoveries are coalescing to inform historians’ understanding of Roman-era Wales, reports George Herd for BBC News. As detailed in the journal Britannia last month, sites unearthed through the aerial surveys include Roman roads, marching camps, forts and villas, as well as a “remarkable” series of stone buildings outside the hillfort at Pen y Gaer.

Roman invaders constructed marching camps during the empire’s campaign to conquer Wales, which lasted from roughly 50 to 80 A.D., according to an RCAHMW statement. Two newly described camps are located in southeast Wales near Caerwent and the Black Mountains, respectively.

“The marching camps are really, really interesting,” Driver tells BBC News. “They are the temporary overnight stops that the Romans build on maneuvers in hostile territory.”

Only two other marching camps have been found in southeast Wales to date, the researchers say in the statement. The new finds suggest the existence of similar sites nearby that may better illuminate the geography of the decades-long conflict between Roman soldiers and members of Celtic tribes in the area, per BBC News.

Crop mark diagram
This diagram shows how crop marks can form over time. Ancient settlements may have dug out or compacted the soil, influencing drainage or soil quality in ways reflected by how plants grow across the landscape today. Crown Copyright / RCAHMW

In its attempts to conquer the region, Rome also constructed numerous forts. The aerial surveys revealed previously unknown forts in the Vale of Gwent at Carrow Hill and at Aberllynfi near Hay-on-Wye, according to the study.

These forts were linked together by roads, some of which may lead archaeologists to additional finds down the line. One newly discovered throughway strikes a path south from Carmarthen to Kidwelly, adding fuel to long-standing speculation that Kidwelly had a Roman fort of its own, according to the statement.

Lockdown measures implemented to slow the spread of COVID-19 have temporarily grounded Driver’s plane, but as he tells BBC News, he hopes to get back in the air soon. Given the fact that the U.K. just experienced its driest May on record, more ancient history may be ripe for discovery.

“Although we had loads come out in 2018, we’ve got this big gaps in Roman Wales that we know should have military installations,” says Driver, “[and] you’ve got to get out in dry weather to find them.”

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