Archaeologists are redrawing Roman maps of Switzerland after traces of long-buried ruins emerged as the country endured the hottest summer on record.
Drought can reveal hidden archaeological sites through "parch marks" created when vegetation above them withers, one of several effects of this year's heat waves, which also exposed World War II wrecks on river beds.
Alerted by a history enthusiast, archaeologists in the Swiss canton of Vaud used a drone to take daily images of fields around Aventicum, the former capital of Roman Helvetia, founded 2,000 years ago after Julius Caesar defeated local tribes. It is now the site of the small town of Avenches.
"These are the richest discoveries made there in the last 50 years, at least over the last two generations of archaeologists," said Jordan Anastassov, archaeologist for Vaud.
The images revealed traces of thermal baths, houses, roads and a possible temple that were previously unknown or dimly understood, many in never-before-excavated areas of the city, which thrived under Roman rule before gradually fading as Germanic incursions increased from the third century onward.
The team of five archaeologists superimposed the discoveries onto maps in purple, filling blank spaces and correcting mistaken markings.
"We are now asking really interesting questions we wouldn't otherwise be asking," said archaeologist Hugo Amoroso.
Some of the traces captured from June to August vanished after mowing and with lower temperatures, but the perimeter of a new pool in the baths is still visible in a partially withered alfalfa field as unseasonably warm weather has persisted in September.
Other buried historical remains have emerged elsewhere in Switzerland and Europe, but many are harder to interpret because they are isolated and lack dedicated researchers.
The Swiss archaeologists will present their findings to peers and may conduct targeted digs later.
"We aren't going to wish for droughts," said Pierre Blanc, director of excavations for the site. "But we're going to make the most of this and keep looking."
