Hidden ice age realm revealed beneath North Sea silt
Scientists have determined that over the last million years, land formations created by a massive ice sheet have been hidden under thick layers of silt. New images from the North Sea reveal this discovery.
Researchers described the latest findings in the scientific journal Science Advances. The uncovering of significant structures beneath the surface of the North Sea was made possible by new, detailed 3D images. The evidence presented also challenges the existing model of early North Sea glaciation.
The structures were hidden in the post-glacial clay layer
Below the ancient glacier, researchers encountered a thick layer of clay covering an area of approximately 3,860 square miles. The clay averages 100 feet in thickness, with some places reaching up to 400 feet. The thickest part is located on the Norwegian side, in the northeast. Researchers believe the clay formed from sediments deposited by the glacier that once moved through this area. On today’s maps, the glacier covers Norway and extends toward the British Isles.
Patterns on the ocean floor come from strong ocean currents
Scientists captured these hidden structures—in "clear and incredible" detail, as they describe—buried under about a kilometer of silt. The images show patterns on the seafloor consistent with the advancement and retreat of a single, large ice sheet, which existed about a million years ago—contradicting theories that smaller ice sheets repeatedly expanded and retreated during this time. These theories were based on numerous scratch marks that some researchers believed were caused by glaciers. However, it turns out they originate from strong ocean currents.
"We see only conclusive evidence of one major ice advance during this period," said Christine Batchelor, senior lecturer in physical geography at the University of Newcastle in the UK and co-author of the new study describing the landforms, in an interview with Live Science. She added that areas outside the current research region might still contain evidence of several more miniature ice sheets.
The scientific team used high-resolution sound wave data to reveal the landforms. As the researchers reported, they were not looking for anything specific and were surprised to find evidence of a single grounded ice sheet—an ice sheet that sits on land rather than on water. From these findings, researchers can reconstruct the glacial past of the region.
Determining how ice behaved during major climate changes is crucial
A giant ice sheet formed during the last glacial period known as the Middle Pleistocene Transition (MPT), which lasted from 1.3 million to 700 thousand years ago. The ice age itself began about 2.6 million years ago and ended 11,700 years ago. The research focused on the MPT because it marks a time when glacial periods suddenly became more intense and shifted from occurring every 40,000 years to every 100,000 years.
"The main reason we are interested in this broad time period from about a million years ago is that this is when climate change occurs," said Batchelor. "Glacial periods become longer and more intense, so there is a lot of effort focused on trying to determine why this change happened," she added.
The new research does not yet provide answers, but understanding where ice spread during critical moments for climate change over a million years ago can help scientists create a picture of the conditions that led to these global transformations and contribute to studying contemporary climate changes.
