Deep valleys buried under the seafloor of the North Sea record how the ancient ice sheets that used to cover the UK and Europe expelled water to stop themselves from collapsing.
October 4, 2022
Deep valleys buried under the seafloor of the North Sea record how the ancient ice sheets that used to cover the UK and Europe expelled water to stop themselves from collapsing.
A new study published this week has surprised the research team, who discovered that the valleys took just hundreds of years to form as they transported vast amounts of meltwater away from under the ice and out into the sea.
This new understanding of when the vast ice sheets melted 20,000 years ago has implications for how glaciers may respond to climate warming today. The study is published in the journal Quaternary Science Reviews.
Tunnel valleys are enormous channels, sometimes up to 150km long, 6km wide and 500m deep (each several times larger than Loch Ness), that drain water from beneath melting ice sheets. There are thousands buried beneath the seafloor of the North Sea that record the melting of ice sheets that have covered the UK and Western Europe over the last two million years.
Lead author James Kirkham, from British Antarctic Survey (BAS) and the University of Cambridge, says, « This is an exciting discovery. We know that these spectacular valleys are carved out during the death throes of ice sheets. By using a combination of state-of-the-art subsurface imaging techniques and a computer model, we have learnt that tunnel valleys can be eroded rapidly beneath ice sheets experiencing extreme warmth. »
The team analyzed « jaw-droppingly detailed » seismic images that provide a 3D scan of the Earth’s buried layers. Informed by delicate clues discovered within the valleys, the authors performed a series of computer modeling experiments to simulate valley development, and test how quickly they formed as the last ice sheet to cover the UK melted away at the end of the most recent ice age about 20,000 years ago.
