A 3D mannequin of a brief part of the stone wall. The scale on the backside of the picture measures 50 cm. Photos had been taken by Philipp Hoy, University of Rostock. The mannequin was created utilizing Agisoft Metashape by J. Auer, LAKD M-V.

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In the autumn of 2021, Jacob Geersen, a marine geologist now on the Leibniz Institute for Baltic Sea Research, was educating a one-week subject course on the University of Kiel. The class was carried out solely aboard a analysis vessel on the Baltic Sea.

Geersen prefers the open-air classroom. “It’s quite intense,” he says, however for a few of the college students, “it’s maybe the best time during their studies.”

During the night time shift every night, college students mapped the form of the seafloor at excessive decision. “Usually if we go somewhere and do these measurements,” says Geersen, “then we find something interesting.” This analysis cruise proved no exception.

One night time, within the Bay of Mecklenburg, off the coast of northern Germany, the scholars fired up the echosounders and mapped a swath of seafloor. “The next day, we downloaded the data,” says Geersen. “And it was then when we were sitting together, we saw that there was something on the seafloor. It was something special.”

They did not comprehend it on the time, however not fairly 70 ft under the floor, they’d stumbled upon a stone wall greater than half a mile lengthy that dated again to the Stone Age — one of many oldest such megastructures on the planet. In analysis printed in PNAS, Geersen and his colleagues say this piece of historical searching structure could have been used to corral and hunt reindeer, including a degree of sophistication to the prehistoric hunter-gatherers who lived 10,000 to 11,000 years in the past.

The Blinkerwall is revealed

Geersen was used to seeing rocks and stones present up on the echosounder as bumpy anomalies scattered throughout the underside of the Baltic Sea, left behind when the glaciers retreated from northern Europe hundreds of years in the past. But again aboard that vessel within the Bay of Mecklenburg, he might already inform that what he was seeing was totally different.

“You saw there is something that kind of meanders through the map,” says Geersen. It was a ridge that ran for six tenths of a mile. “I thought it’s very likely that these are rocks, one next to the other, lined up,” he says.

A 12 months later, Geersen, his colleagues and a brand new batch of scholars returned to that very same website. They lowered a digicam down, and confirmed this ridge was made up of hundreds of rocks that fashioned a type of wall standing about 1.5 ft tall on common.

“It’s usually small stones — like tennis or soccer ball size — so movable stones,” says Geersen. “But then at some places where we have a large stone, the direction of the wall changes.”

Geersen did not know the way such a construction, which the researchers dubbed the “Blinkerwall” after a close-by underwater mound known as Blinker Hill, might have fashioned naturally.

“It was only when we went to the archaeologists that they said, ‘You may have found something very significant,'” he says.

“I was probably the most skeptical of the entire team,” remembers Berit Eriksen, a prehistoric archaeologist on the University of Kiel who studies the individuals who arrived in northern Europe when the glaciers retreated after the final Ice Age 10,000 to twenty,000 years in the past. When she examined the construction from the Bay of Mecklenburg, a line from Sherlock Holmes got here to thoughts: “When you have eliminated the impossible, whatever remains, however improbable, must be the truth.”

“Archaeologists never speak of ‘truth,'” admits Eriksen, “but I’m running out of things to eliminate in terms of natural stuff. That’s my problem.”

Eriksen reviewed the information and have become more and more satisfied that the construction was made by prehistoric people who’d used plenty of smaller stones to attach the bigger unmovable rocks right into a wall. “I don’t believe in UFOs, so it’s got to be manmade,” she concludes. She and the opposite archaeologists on the challenge agreed that the wall was doubtless utilized by hunter gatherers 10,000 to 11,000 years in the past in the course of the Stone Age to assist them herd and hunt reindeer by the a whole bunch.

How to hunt a whole bunch of reindeer within the Stone Age

“The only way you can kill this amount of reindeer is if you drive them into a shooting blind, if you cut them off at the pass somewhere,” explains Eriksen. And reindeer are identified to comply with these sorts of stone partitions naturally, even stout ones just like the Blinkerwall.

“There would have been water at the other side,” says Eriksen. So the reindeer would have develop into trapped between the wall and the water, permitting the hunters mendacity in wait to fireplace their arrows on the reindeer. Eriksen says these prehistoric individuals had been nomadic, however this wall suggests they could have had a daily migration route, one that might have introduced them again to this spot 12 months after 12 months.

“If you build a structure like that,” says Eriksen, “you’re someone who knows the entire area extremely well. You’re not just moving around an unknown landscape. You don’t just hope you can find a reindeer that day. You plan. You know where the reindeer will come next year.” It’s a idea that archaeologists have kicked round for some time, however she says this wall helps affirm it might have been true in prehistoric Europe.

Ultimately, the realm was flooded, forming the Baltic Sea we all know right this moment and submerging this piece of searching structure below the water.

Ashley Lemke, an underwater archaeologist on the University of Wisconsin, Milwaukee, was not concerned within the examine. She mentioned the analysis was robust — and carried out below difficult circumstances.

“I know this personally — working underwater is not easy,” says Lemke, who has found related stone partitions in Lake Huron, one of many Great Lakes beside Michigan.

Lemke explains that these outcomes reinforce the argument that individuals residing in the course of the Stone Age had been extra refined and nuanced than we have a tendency to offer them credit score for. “We always think of them on the brink of starvation, trying to scrape a living out of the landscape. And that’s just not true,” she says. Instead, “people in Europe were building things before Stonehenge, before these more classical structures that we think of.”

“This is actually really early examples of almost animal domestication,” Lemke continues. “Like before you start keeping animals in pens permanently, you’re kind of making fences to hunt them, which I think is really interesting.” This observe could have ultimately led to livestock herding.

To affirm this wall was made by prehistoric individuals and used to hunt, the researchers will want extra archaeological proof of hunting-related exercise. Berit Eriksen says such clues needs to be there, given the hunters would have needed to look ahead to the reindeer to indicate up.

“You’d have to eat while you’re there, so you can see if there are small bits of charcoal,” she says. It could also be potential to excavate arrowheads or historical DNA. In addition, “they would have defecated,” Eriksen says. “So you can find stuff — traces of people — if you’re lucky.”