From BBC
Icebergs as large as cities, potentially tens of kilometres wide, once roved the coasts of the UK, according to scientists.
Researchers found distinctive scratch marks left by the drifting icebergs as they gouged deep tracks into the North Sea floor more than 18,000 years ago.
It’s the first hard evidence that the ice sheet formerly covering Britain and Ireland produced such large bergs.
The findings could provide vital clues in understanding how climate change is affecting Antarctica today.
The scientists searched for fingerprints of giant icebergs using very detailed 3D seismic data, collected by oil and gas companies or wind turbine projects doing ocean surveys.
This is a bit like doing an MRI scan of the sediment layers beneath the present-day seafloor, going back millions of years.
The researchers found deep, comb-like grooves, interpreted to have been created by the keels of large icebergs that broke off the British-Irish ice sheet more than 18,000 years ago.
Some of these scratch marks are as close as 90 miles (145km) to Scotland’s present-day east coast.
“We found [evidence of] these gigantic tabular icebergs, which basically means the shape of a table, with incredibly wide and flat tops,” said James Kirkham, marine geophysicist at the British Antarctic Survey and lead author of the new study, published in the journal Nature Communications.
“These have not been seen before and it shows definitively that the UK had ice shelves, because that’s the only way to produce these gigantic tabular icebergs.”
Ice shelves are floating platforms of ice where glaciers extend out into the ocean.
By analysing the size of the grooves, the scientists estimate that these icebergs could be five to tens of kilometres wide and 50-180m thick, although it’s difficult to be exact.
That means they would have covered an area roughly as big as medium-sized UK cities like Norwich or Cambridge.
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