By Katrin Bennhold

New York Times News Service

BORTH, Wales — There is a poem children in Wales learn about the sunken kingdom of Cantre’r Gwaelod, swallowed by the sea and drowned forever after. On a quiet night, legend has it, one can hear the kingdom’s church bells ringing.

When the sea swallowed part of Britain’s western coastline this year and then spat it out again, leaving homes and livelihoods destroyed but also a dense forest of prehistoric tree stumps more exposed than ever, it was as if one had caught a faint glimpse of that Welsh Atlantis.

The submerged forest of Borth is not new. First flooded some 5,000 years ago by rising sea levels after the last ice age, it has been there as long as locals remember, coming and going with the tides and occasionally disappearing under the sand for years on end. But the floods and storms that battered Britain this year radically changed the way archaeologists interpret the landscape: A quarter-mile-long saltwater channel cutting through the trees, revealed by erosion for the first time, provided a trove of clues to where human life may have been concentrated and where its traces may yet be found.

“We used to think of this as just as an impenetrable forest — actually this was a complex human environment,” said Martin Bates, a geoarchaeologist at the University of Wales Trinity St. David, who oversees the excavation work in Borth on a beach he played on as a toddler. “The floods have opened our eyes as to what’s really out there.”

Scanning the army of ghostly spikes protruding from the sand here one recent morning, Bates said it was as if nature were making a point: The recent torrential rains, linked by a growing number of climatologists to human-induced climate change, have provided an ancient laboratory to study how humans coped with catastrophic climate change in the past.

Nicholas Ashton, the curator of Paleolithic and Mesolithic collections at the British Museum, has been organizing “fossil road shows” in which he invites civilians to bring in any potential archaeological finds and have them identified. (One man recently showed up with a 6-inch-long hippo tusk and a well-preserved ax, both found locally and both more than half a million years old.)

Having those extra eyes on the ground can make all the difference in coastal areas, Ashton said, for what the sea reveals, it tends to reclaim almost as soon. He learned this lesson firsthand.

In May 2013, shortly after the first set of storms, Ashton commissioned Bates, an old university friend, to work on Britain’s east coast in Norfolk. The beach near Happisburgh (pronounced hays-boro), a longstanding archaeological site, had suffered severe erosion. Ashton, an expert in early humans, wanted a geophysical survey to map any channels or rivers that might lie beneath about 30 feet of sediment. Some of these channels, he reckoned, might contain evidence of early humans because sources of freshwater would have been natural gathering spots.

Footprints found

It was on their second visit, on May 10, that Bates noticed some indentions on the otherwise flat horizons of the laminated silts recently laid bare on the beach. The humps and bumps looked familiar. He told Ashton: “They’re just like the human footprints in Borth.”

Footprints of humans and animals in Borth had been dated to about 6,000 years ago. The site in Happisburgh was 900,000 years old, a time when mammoths and hippos still roamed in these parts. No human bones or prints that old had ever been found in Britain.

Could this be possible?

A frantic race against time began. Every day, the shape of the prints would blur a little more as the coming tide eroded the contours of heels, toes and arches. A team led by Dr. Sarah Duffy from the University of York arrived to apply a technique called multi-image photogrammetry, taking about 150 digital photographs of the surface area containing the prints and feeding it into a program that created a three-dimensional model. By the time another team had come to do some laser scanning, it was too late: The prints were barely visible.

Panicked, scientists lifted from the site a 130-pound block of sediment with one faint print on top, to have it analyzed at the National Oceanography Center. It is the only remaining physical evidence of the footprints: Before the month was out, all traces of them had vanished. It was a powerful reminder of both the resilience and the fragility of human life.

“What had been preserved for nearly 1 million years was taken back by the sea in the space of 10 days,” Ashton said.

Initially skeptical, he said he knew the footprints were real when Duffy’s computer images landed in his inbox sometime last June. “I thought, bloody hell, we are dealing with something quite extraordinary here,” he said.

The footprints, the oldest known outside Africa, probably belonged to a family group of Homo antecessor, a cousin of Homo erectus that possibly became extinct when Homo heidelbergensis from Africa settled in Britain about 500,000 years ago, he said. Using foot-length-to-stature ratios, scientists estimate that the male was perhaps 5 feet 9 inches tall, and the smallest child a little less than 37 inches.

Mysterious species

Little is known about this early human species. Fossil skeletons in Atapuerca, Spain, from around the same time suggest that they walked upright and looked much like modern humans, although their brains were smaller. If they had language, it was primitive. Living at the tail end of an interglacial era, as winters were growing colder, they may have had functional body hair. So far, there is no evidence that they used clothes, shelter, fire or tools more complex than simple stone flakes.

Standing on the ridge above Cardigan Bay in Borth, Bates described what the area would have looked like at the height of the last ice age some 20,000 years ago: more than half a mile of ice overhead and dry land stretching across today’s North Sea. The sea level was 400 feet lower than it is today.

“You could have walked from Denmark to Yorkshire in those days,” he said.

About 10,000 years ago, temperatures warmed sharply, by eight to 10 degrees Fahrenheit. By that time, the European ice sheets had melted, but the much thicker North American sheets took much longer. While the climate had warmed to today’s levels, allowing mixed oak woodland to grow and humans to recolonize Britain, the sea level remained some 130 feet lower for another 3,000 years.

When it did rise, it would have been traumatic for the population, wiping out whatever settlement there was, and eventually the forest of Borth. The displaced humans of the time, Bates said, were prehistoric refugees from climate change.

“Even in the reduced life span of the day, the coastline would have advanced dramatically,” said Bates, who is convinced that stories like Cantre’r Gwaelod originated in this period.

Similar tales abound on the western European seaboard: There are Cornish and Breton versions, and variations of the theme exist in Jersey and the Orkney Islands. The ultimate legend, of course, is Atlantis, which Plato placed somewhere in the North Atlantic.

“It was a traumatic geological event, and people turned it into a story to make sense of it,” said Gerald Morgan, a retired head teacher and local historian in nearby Aberystwyth.

The same thing is happening again today, as Britons survey the damage of the past couple of years of flooding and storms and ponder the future. The submerged forest in Borth, little known outside a small radius here, has once again become part of local lore. Its haunting shapes are featured in poetry slams and in storytelling evenings, and modern-day performances of Cantre’r Gwaelod have been staged on the beach, said Morgan and his wife, Enid.

Have they ever heard the bells?

Enid Morgan smiled. “I knew someone who did.”