The Famous Bering Land Bridge Was More Like a Swamp, Geologists Say
taylorvich writes:
https://gizmodo.com/the-famous-bering-land-bridge-was-more-like-a-swamp-geologists-say-2000539043
During the last Ice Age, modern-day Siberia and Alaska were connected by a landmass that allowed animals-and ancient humans-to migrate across what is now the Bering Sea. While scientists have long assumed that the now-submerged topography resembled the Ice Age landscape of these two regions, recent research paints a more complex picture.
Geologists suggest that between 36,000 and 11,000 years ago, the Bering Land Bridge may have been less an arid steppe grassland and more a boggy ecosystem crisscrossed by rivers. This complicates scientists' understanding of the iconic landmass and how its landscape would have facilitated or impeded the spread of different species. The scientists presented their work at the American Geophysical Union (AGU) Annual Meeting last week.
"We've been looking on land to try to reconstruct what is underwater," Jenna Hill of the U.S. Geological Survey, who took part in the research, said in an AGU statement. "But that doesn't really tell you what was on land that is now submerged between Alaska and Siberia."
It's worth noting that the name "Bering Land Bridge" is often misleading. The landscape was not a literal bridge that necessarily compelled ancient humans and animals to cross it-it was a sprawling region in its own right that allowed for species to spread between Siberia and North America when sea levels were about 400 feet (122 meters) lower than today. It was a viable habitat in its own right.
In 2023, Hill and her colleagues conducted sonar readings and extracted sediment cores from regions of the Bering Sea floor where previous research had indicated the likely presence of prehistoric lakes.
"We were looking for several large lakes," said Sarah Fowell, a paleogeologist at the University of Alaska Fairbanks, who was also involved in the research. "What we actually found was evidence of lots of small lakes and river channels."
In addition to highlighting the rapid change from freshwater to marine sediment, the cores revealed prehistoric lake sediments, fossils, pollen, and DNA left behind in sediments. Specifically, the pollen indicated the presence of woody trees, while the fossils hinted at widespread freshwater across the Bering Land Bridge.
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