Global warming strikes again!
No doubt this was caused by human induced global warming...
It happened 60,000 years ago, so we'll concede that we're a bit late with the news, but scientists have uncovered evidence of the largest ever flow of sand and mud, off the coast of north-west Africa. Researchers report in Nature that over the course of mere hours, or days, some 225 billion metric tonnes of sediment was dumped …
Ah this takes me back to long cold wet geology fieldtrips along the coastline of Cardigan Bay which is largely made up of 400 million year old mudflows called turbidites or greywackes. Possibly the ugliest rock in the world.
These underwater landslides pose a real threat to submarine cables (and you were wondering when the IT angle would be along). The 1929 Newfoundland Banks (Magnitude 7.2) earthquake dislodged a series of huge turbidity currents (estimated at 200km3) that severed 12 TransAtlantic cables. The times of the breaks are precisely known, so it was also possible to work out the speed - about 60mph.
There's a short movie of a simulated current at:
Oh and they're dangerous to humans, a current can also trigger tsunamis, such as the Storegga slide mentioned in the article around 6000BC which would have put a 20m tsunami over most of the Scottish North Sea coast. This is a real threat in many places because the edges of the continental shelves are piled high with sediments dumped by rivers and glaciers during the last glacial when sea levels were much lower. Even a small quake could set this waterlogged sludge slip-sliding its way down the continental shelf. Which means that we have to think of tsunamis in areas that aren't normally affected by plate tectonic movements - such as the North Sea and the Atlantic coast of Canada.
I choose Paris as my icon because she slides down on a regular basis.
Mike Richards wrote:
> There's a short movie of a simulated current at:
This was the winner of the 2005 "most boring video on the internet" competition. Mind you, this was before YouTube really got going.
Why am I wasting my Friday work time watching this when I could be wasting it elsewhere...
So, if any preglacial cilization thrived over those shores, the archeological evidence may be lying buring on the ocean floor, but since we dont usually dig in the mid of the ocean floor (at least as usual as we do above the ground) then this explains why there preglacials civilizations didn't exist!
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