Traces of Stone Age hunter-gatherers discovered in the Baltic Sea

In the fall of 2021, geologists discovered an unusual row of stones, almost a kilometer long, at the bottom of Mecklenburg Bay. The site is located approximately 10 kilometers offshore from Rerik, at a water depth of 21 meters. The approximately 1,500 stones are aligned so regularly that a natural origin seems unlikely.

A team of researchers from different disciplines concluded that Stone Age hunter-gatherers probably built this structure around 11,000 years ago to hunt reindeer. This discovery represents the first discovery of a Stone Age hunting structure in the Baltic Sea region.

The scientists present their findings in the Proceedings of the National Academy of Sciences.

Discovery of the hunting site

Originally, a team of researchers and students from Kiel University (CAU) wanted to study manganese crusts on a ridge of basal till that forms the seafloor about 10 kilometers off the coast of Rerik, in the Mecklenburg Bay. During their investigation, however, they discovered a regular row of stones 970 meters long.

The structure consists of around 1,500 stones, most measuring a few dozen centimeters in diameter, which connect several large one-meter boulders. The researchers reported their discovery to the Mecklenburg-Vorpommern state agency for the preservation of culture and monuments (Landesamt für Kultur und Denkmalpflege Mecklenburg-Vorpommern LAKD MV), which then coordinated further investigations.

The stone wall is located on the southwest flank of a basal till ridge whose orientation is roughly parallel to an adjacent basin to the south, likely an ancient lake or peat bog. Today the Baltic Sea is 21 meters deep at this location. Thus, the stone wall had to be built before sea levels rose significantly after the end of the last ice age, which occurred around 8,500 years ago. Large parts of the previously accessible landscape were eventually flooded at this time.

Scientists from the Leibniz Institute for Baltic Sea Research in Warnemünde (IOW), the CAU Kiel Marine Science research center, the University of Rostock, the Center for Baltic and Scandinavian Archeology (ZBSA, which has since 2024 part of the Leibniz Center for Archeology LEIZA), the German Aerospace Center (DLR), the Alfred Wegener Institute, the Helmholtz Center for Polar and Marine Research (AWI) as well as the LAKD MV used modern geophysical methods to create a detailed 3D model of the wall and reconstruct the structure of the ancient landscape. . Using sediment samples from the adjacent basin to the south, it was possible to determine the possible time period during which the wall could have been constructed. In addition, research divers from the universities of Rostock and Kiel explored the stone wall.

Results to date

“Our investigations indicate that a natural origin of the underwater stone wall as well as construction in modern times, for example in connection with the laying of submarine cables or stone harvesting, are unlikely. “The methodical arrangement of the many small stones that connect the large, immobile rocks goes against this,” explains Jacob Geersen, lead author of the study. As part of the new IOW research theme “Shallow-water processes and transitions to the Baltic scale”, Geersen studies geological and anthropogenic processes in the Baltic Sea region.

If we exclude natural processes and a modern origin, the stone wall could only have formed after the end of the last ice age, when the landscape was not yet flooded by the Baltic Sea.

“At this time, the total population of Northern Europe was probably fewer than 5,000. One of their main sources of food was reindeer herds, which migrated seasonally across the post-glacial landscape to sparse vegetation. The wall was probably used to guide reindeer towards a bottleneck between the adjacent banks of the lake and the wall, or even into the lake, where Stone Age hunters could kill them more easily with their weapons”, explains Marcel Bradtmöller from the University of Rostock.

Comparable prehistoric hunting structures have already been discovered in other parts of the world, for example at the bottom of Lake Huron (Michigan), at a depth of 30 meters. Here, American archaeologists have documented stone walls as well as hunting blinds built to hunt caribou, the North American equivalent of reindeer. The Lake Huron and Mecklenburg Bight stone walls share many characteristics, such as a location on the flank of a topographic ridge, as well as a subparallel trending lake shore on one side.

As the last reindeer herds disappeared from our latitudes around 11,000 years ago, when the climate warmed and forests expanded, the stone wall was probably not built after that time. This would make it the oldest human structure ever discovered in the Baltic Sea.

“Although many well-preserved archaeological sites from the Stone Age are known in the Bay of Wismar and along the coast of Mecklenburg-Vorpommern, they are located in much shallower water depths and date back to most of the Mesolithic and Neolithic periods (ca. 7,000 to 1,000 years ago. 2,500 BC),” explains Jens Auer from the State Office for Culture and Monument Preservation of Mecklenburg-Vorpommern (LAKD MV) , who participated in the exploration and sampling of many of these sites.

And after?

The stone wall and surrounding seabed will be studied in more detail using a side scan sonar, a sediment echo sounder and a multibeam echo sounder. In addition, research divers from the University of Rostock and archaeologists from LAKD MV are planning further diving campaigns to excavate the stone wall and its surroundings for archaeological finds that may aid in the interpretation of the structure.

Luminescence dating, which can be used to determine when a stone’s surface was last exposed to sunlight, can help determine a more precise date when the stone wall was built. In addition, the researchers intend to reconstruct the surrounding ancient landscape in more detail.

“We have evidence of the existence of comparable stone walls in other places in the Mecklenburg Bay. These will also be systematically studied,” explains Jens Schneider von Deimling from the University of Kiel.

Overall, the surveys can make a significant contribution to the understanding of the life, organization and hunting methods of Early Stone Age hunter-gatherers.