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Cambridge scientists’ ‘MRI scan of the Earth’ reveals extraordinary ice age landscapes beneath North Sea



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Cambridge scientists have carried out something akin to an ‘MRI scan of the Earth’ to reveal remarkable ice age landscapes beneath the North Sea.

The discovery, made using 3D seismic reflection technology, offers new insight into how ice sheets reacted in the past to a warming planet - information that could help the researchers predict how those in Antarctic and Greenland could be impacted by climate change.

Image of an esker (a sedimentary cast of a meltwater channel formed beneath an ice sheet) that a research team has discovered within a tunnel valley using the new 3D seismic reflection data. Picture: British Antarctic Survey
Image of an esker (a sedimentary cast of a meltwater channel formed beneath an ice sheet) that a research team has discovered within a tunnel valley using the new 3D seismic reflection data. Picture: British Antarctic Survey

The international team, including British Antarctic Survey and University of Cambridge scientists, found huge seafloor channels each 10 times wider than the River Thames.

These previously undetectable landscapes formed beneath the huge ice sheets that covered much of the UK from thousands to millions of year ago.

The ‘tunnel valleys’, which are buried hundreds of metres beneath the North Sea floor, are the remnants of giant rivers that acted like a plumbing systems for these ancient ice sheets as they melted amid rising air temperatures.

James Kirkham, from BAS and the University of Cambridge, who is lead author of the paper published in Geology on the research, said: “The origin of these channels was unresolved for over a century. This discovery will help us better understand the ongoing retreat of present-day glaciers in Antarctica and Greenland.

“In the way that we can leave footprints in the sand, glaciers leave an imprint on the land upon which they flow. Our new cutting edge data gives us important markers of deglaciation.”

A map of the North Sea showing the distribution of buried channels (tunnel valleys) that have been previously mapped using 3D seismic reflection technology. The limit of the last ice sheet to cover the UK (around 21,000 years ago) is overlain. Picture: British Antarctic Survey (51336788)
A map of the North Sea showing the distribution of buried channels (tunnel valleys) that have been previously mapped using 3D seismic reflection technology. The limit of the last ice sheet to cover the UK (around 21,000 years ago) is overlain. Picture: British Antarctic Survey (51336788)

Industry partners provided the technology for the work, which uses sound waves to generate detailed three-dimensional representations of the ancient landscapes beneath the Earth’s surface, in a manner comparable to how magnetic resonance imaging (MRI) scans image structures within the human body.

Incredibly, the technology is able to image features as small as a few metres in size - even if they are buried under hundreds of metres of sediment.

Comparison of the buried landforms (glacial footprints) found within the tunnel valleys using the new 3D seismic reflection data (left column images) for the first time, and examples of modern landforms exposed at the margins of retreating glaciers in Svalbard and Iceland. Picture: British Antarctic Survey (51336799)
Comparison of the buried landforms (glacial footprints) found within the tunnel valleys using the new 3D seismic reflection data (left column images) for the first time, and examples of modern landforms exposed at the margins of retreating glaciers in Svalbard and Iceland. Picture: British Antarctic Survey (51336799)

Comparing the ‘ice fingerprints’ to those left beneath modern glaciers enabled the team to reconstruct how the ancient ice sheets behaved as they receded.

Dr Kelly Hogan, co-author and a geophysicist at BAS, says: “Although we have known about the huge glacial channels in the North Sea for some time, this is the first time we have imaged fine-scale landforms within them.

Smaller channels and islands revealed at the base of a tunnel valley for the first time using the new 3D seismic reflection data. Picture: British Antarctic Survey (51336776)
Smaller channels and islands revealed at the base of a tunnel valley for the first time using the new 3D seismic reflection data. Picture: British Antarctic Survey (51336776)

“These delicate features tell us about how water moved through the channels - beneath the ice - and even how ice simply stagnated and melted away. It is very difficult to observe what goes on underneath our large ice sheets today, particularly how moving water and sediment is affecting ice flow and we know that these are important controls on ice behaviour.

“As a result, using these ancient channels to understand how ice will respond to changing conditions in a warming climate is extremely relevant and timely.”

This compares the resolution of the new high-resolution 3D seismic reflection data to previous 3D seismic data from this region. The new data revolutionises our ability to image these buried channels and their internal structures, as demonstrated by the contrast between the left and right of the image. Picture: British Antarctic Survey (51336805)
This compares the resolution of the new high-resolution 3D seismic reflection data to previous 3D seismic data from this region. The new data revolutionises our ability to image these buried channels and their internal structures, as demonstrated by the contrast between the left and right of the image. Picture: British Antarctic Survey (51336805)

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