Willian sent in this link and it opens a fascinating subject. At https://news.yahoo.com/news/north-seas-hidden-ice-age-230234332.html … a spectacular Ice Age landscape has been revealed beneath the North Sea. Deep, kilometre wide channels gouged out of the sea bed by fast flowing rivers of water – presumed to be melt water from ice. The link has images but for the best set of views go to www.dailymail.co.uk/sciencetech/article-9970017/ … These gouged out tunnel valleys, we are told, were formed during the death throes of an ice sheet – and are supposed to represent what might happen in Greenland and Antarctica if global warming takes off. This is according to a spokesperson speaking to the BBC. Or prompted by the BBC. He goes on to elaborate on similarities they think exist under modern ice sheets. However, it is pretty obvious the gouges were made at the end of the Late Glacial Maximum. The article in Geology journal says the gouges are on large scale in comparison with water leaking out of the bottom of ice sheets in the modern world.
The discovery was made possible by seismic sound wave survey techniques. This was developed to look at the sea floor sediments to see if they were useful areas in the search for oil and gas. Fossil fuel industry brings the North Sea basin alive. What they found was that the accumulation of thick ice over NW Europe was followed by a 'mass retreat' when temperatures rapidly increased. Comparing it to modern ice sheets is irrelevant as they are not going to melt quickly. At the end of the Late Glacial Maximum it was quite different. The temperatures jumped by 10 degrees in a short space of time -m less than ten years. Hence, ice meltwater cascaded down the North Sea basin.
See also https://phys.org/news/2021-09-mri-scan-reveals-spectacular-ice.html … which provides a link to the article at https://doi.org/10.1130/G49048.1
See also https://sciencenorway.no/geology-ice-age/scientists-are-seeing-ice-age-b… … where it claims 3D images are able to seven plot the beginning of the Ice Age, 2 million years ago. They add that there have been 30 to 40 Ice Ages within those 2 million years. They affected Norway in the form of the fjiords, mountains, valleys etc. However, little is known about what was actually going on during the Ice Ages – but the new survey of the North Sea basin promises to change that by shining some light. It seems, as in Canada, the last ice sheet, the LGM, removed all evidence of earlier ice sheets from the land. Hence, geologists in Norway are hoping the sea bed may differ – and provide what is missing.
They mention in an article in Nature Communications that the Norwegian Trench was formed by ice stream activity – the biggest of all the gouges. Also, that the Shetland islands, once a much larger land mass. It then adds – but strangely, this much bigger land mass, was not scoured by ice during various periods of the Ice Ages. Instead, rivers flowed out of Shetland and brought sediments that subsequently circled the Shetlands, located as it is on the continental shelf system.
A team from the Norwegian Geological Survey and the University of Cambridge in the UK were responsible for the article – see www.nature.com/articles/s41467-020-16776-7