Ice age secrets unveiled: Massive glacier found beneath North Sea
Scientists have determined that over the last million years, land formations created by a massive ice sheet have been concealed under thick layers of silt. New images from the North Sea reveal these hidden formations.
Researchers discussed these recent discoveries in the scientific journal Science Advances. Identifying significant structures beneath the surface of the North Sea became possible due to new, detailed 3D imagery. This evidence also challenges the existing model of early North Sea glaciation.
The structures were hidden in the post-glacial layer of clay
Following the ancient glacier, researchers encountered a thick layer of clay spanning approximately 10,000 square kilometres, with an average thickness of about 30 metres, reaching up to 120 metres in some areas. The thickest section is located on the side of Norway, in the northeast. Researchers believe this clay formed from sediments deposited by the glacier that once traversed this region. According to current maps, the glacier covered Norway and extended towards the British Isles.
Patterns on the seabed come from strong ocean currents
Scientists captured these hidden structures buried under about a kilometre of silt in "clear and incredible" detail. The images exhibit patterns on the seafloor consistent with the advance and retreat of a single, large ice sheet that existed roughly a million years ago. This finding contradicts theories that smaller ice sheets repeatedly advanced and retreated during this period. These theories were based on numerous scratch marks previously believed to be caused by glaciers. However, they have now been determined to 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 smaller ice sheets.
The scientific team utilized high-resolution sound wave data to reveal the landforms. As reported by the researchers, they were not searching for anything specific and were surprised to uncover evidence of a single grounded ice sheet — an ice sheet that sits on land rather than water. From these findings, researchers can reconstruct the region's glacial past.
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 concluded 11,700 years ago. The research focused on the MPT because it marks a period when glacial cycles abruptly 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.
While the new research does not yet provide definitive answers, understanding where ice advanced during critical moments for climate change over a million years ago can help scientists piece together a picture of the conditions that led to these global transformations. It also contributes to the study of contemporary climate changes.
