http://www.bbc.co.uk/news/science-environment-27224243
I love listening to the Radio 4 Shipping Forecast, particularly the one at 00:48 (after midnight, so I guess that you will never have heard it). There is a long list of Sea Areas & Coastal Weather Stations; I think that it should be played in every school every day, as these areas are part of the genetic of England. Look closely at the map below & you will see ‘Dogger’ which is also the location for the “Dogger Bank”:
Just before I begin talking about Dogger Bank, look again at the map, and see the (yellow) land at top right, above where it says “North Utsire”; that is at the far southern end of Norway, and Norway will figure again very soon, and in a surprising way.
Dogger Bank is in the middle of the North Sea, and the North Sea is relatively a shallow sea (about 90 metres (300 ft) deep). The Bank itself is a 20 m (66 ft) high sandbank. In fact, Viking, Forties, Dogger, Fisher, Sole and Bailey are *all* named after sandbanks. The Dogger is probably a “moraine” (there are also a lot of those north of my home-town of Hull). A moraine is formed by a glacier. A glacier appears to us to be stationary but, if observed with a time-lapse camera, can quickly be seen to be in constant movement from the rear to the front of the glacier. As the ice moves, it carries silt with it--and sometimes entire boulders as well--and that silt & sand gets deposited under the glacier (which is a slow process) and also at the ‘snout’ of the glacier (which is a much quicker process).
Dogger Bank has long been known by the fishermen to be one of the richest fishing areas in the North Sea. There is, however, one *very* surprising aspect to it... Ever since fishermen have been using trawl nets, they have been pulling up from out of the sea large amounts of moor peat, remains of mammoth, lion and rhinoceros and even, on occasion, Paleolithic hunting artefacts. You see, about 9,000 years ago the sea-levels were much lower than now†, and Dogger Bank was part of a much larger land called “Doggerland”, and it was possible for men & animals to walk to & from the continent & Britain. It looks likely that there may have even been villages in Doggerland, but as the sea-levels began to rise, only the highest parts of Doggerland were left above the waters - those were the parts that we now know as Dogger Bank, and none was more than 5m above the water:
2 events then occurred, and either (or both) could have been the death knell for Doggerland‡.
The first was a submarine landslide off the coast of Norway, known as the “Storegga Slide”. That involved the collapse of some 3,000 cubic km of sediment (enough to cover all of Scotland to a depth of 8m). That would have released a mega-tsunami that would have devasted all life on Doggerland.
As if the tsunami wasn’t bad enough, at about the same time Lake Agassiz began to empty. The Lake was composed of melted glacier-waters, and was positioned in North America; it was the largest-ever fresh-water lake. The Hudson Bay ice finally melted enough to release the Lake Agassiz water and, across a period of about 2 years, sea-levels worldwide rose sufficiently to completely drown Doggerland.
†(sea-levels much lower 9,000 years ago than now) It was the bitter end of the last ice-age; much of the Earth’s water was held within ice & snow, glaciers or Lake Agassiz.
‡(flooding from “Storegga Slide” + Lake Agassiz + rising sea-levels) The same 3 events that caused Doggerland to become submerged possibly also caused the Mediterranean Sea to reappear (and submerged Atlantis?!). I understand there to be a submarine land-bridge at the Gibraltar Strait (Arabic: مضيق جبل طارق, Spanish: Estrecho de Gibraltar) (the Camarinal Sill) which itself is eroded by strong currents through the Strait. The current minimum depth (300m, 980 feet) of the strait is much more than the 120m/390 foot estimate for sea-level rise since the last major glaciation. It is known that ‘Middle Earth’ (the literal meaning of ‘Mediterranean’) was dry 5m years ago, but the evidence of River morphology from modern sonar analysis of the Mediterranean sea-bed perhaps suggests a more recent dry period. I would certainly like to think that.
--------- Alex Kemp