In the deep blue waters of Aafs Bay, located in northern Denmark, archaeologists are examining ancient coastal settlements that were lost to rising sea levels over 8,500 years ago.
This summer, divers ventured about 26 feet down near Alfus, the second largest city in Denmark, collecting evidence of Stone Age habitats from the seabed.
This endeavor is part of a $15.5 million international project spanning six years, financed by the European Union, focusing on parts of the Baltic and North Seas. The team consists of researchers from Alfus, Bradford University in the UK, and the German Institute for Historical Coastal Research.
The main aim is to investigate the submerged landscapes of Northern Europe and discover Mesolithic settlements, especially as offshore wind farms and other marine infrastructures continue to expand.
Impact of Rising Sea Levels Post-Ice Age
So far, most evidence has primarily come from inland Stone Age coastal areas, according to Peter Mo Astrap, an underwater archaeologist leading the excavations in Denmark.
“Here we actually have an old coastline. There are villages right by the shore,” he explained. “What we’re trying to uncover is how life was in these coastal settlements.”
After the last ice age, melting ice sheets caused global sea levels to rise, submerging Stone Age communities and pushing hunter-gatherers inland.
About 8,500 years ago, the sea levels were rising at a rate of 6.5 feet per century, Moe Astrup noted.
Moe Astrup and his colleagues from the Moesgaard Museum in Højbjerg excavated around 430 square feet in a settlement they recently discovered off the coast.
A “Time Capsule” of History
Initial dives have revealed animal bones, stone tools, arrowheads, and small fragments believed to be rudimentary tools. The researchers are using an underwater vacuum to carefully collect materials for later analysis.
They hope to uncover more traces of fishing tools like harpoons or fish hooks in the future.
“It’s essentially like a time capsule,” Moe Astrup remarked. “As sea levels rise, everything is preserved in an oxygen-free environment… time stands still.”
“We find wood that’s completely intact,” he continued. “We’ve even found hazelnuts… everything remains well preserved.”
Excavations in the shallow bay of Alfus, as well as in locations along the German coast, will continue, expanding to two more inhabited sites in the North Sea.
Thousands of years ago, sea levels surged, especially affecting areas connecting Britain to continental Europe, resulting in what is now known as Dog Garland, submerged beneath the southern North Sea.
To better understand the rapid rise in water levels, Danish researchers are employing dendrochronology, or the study of tree rings.
Submerged tree stumps preserved in silt can be accurately dated, revealing insights about the ancient forests along the coast.
“When these trees die along the coast, we can determine this very precisely,” said Jonas Ogdal Jensen from the Arboretum Museum at the Moesgaard Museum, peering into the trunk of an ancient tree through a microscope.
“It provides insights into how sea levels have fluctuated over time.”
As the world tackles climate-driven sea levels today, researchers are eager to learn how Stone Age societies adapted to shifting coastlines more than 8,000 years ago.
“What that meant for the people is a tough question to answer,” Mo Astrap acknowledged. “But it dramatically altered the landscape, clearly having significant long-term effects.”
Globally, sea levels have risen by about 1.7 inches over the decade leading up to 2023.
