Posted on 01/05/2007 4:42:11 PM PST by blam
Dating a massive undersea slide
Sid Perkins
From San Francisco, at a meeting of the American Geophysical Union
Pieces of moss buried in debris deposits along the Norwegian coast have enabled geologists to better peg the date of an ancient tsunami and the immense underwater landslide that triggered it. Carbon dating of the newly unearthed moss suggests that the landslide occurred about 8,100 years ago.
Sometime after the end of the last ice age, the largest landslide known to geologists took place off the coast of Norway. Called the Storegga slide, this slump of seafloor sediments included about 3,000 cubic kilometers of material. That's enough mud to cover the entire United States to a depth of about 30 centimeters, says Stein Bondevik, a geologist at the University of Tromsø in Norway.
The tsunami created by the slide scoured coastal sites in Norway, England, Scotland, and Greenland, in some places to heights of 20 meters above sea level. Scientists have previously used carbon dating of seeds, twigs, and other organic material in sediment layers deposited by the tsunami to date the Storegga slide. However, the organisms in those samples could have been long dead when the tsunami occurred and therefore might have provided artificially old date estimates, says Bondevik.
Now, he and his colleagues report that they have unearthed material that was alive when the tsunami buried it. The pieces of moss, found within an 80-cm-thick layer of sand and broken shells at two sites along the western coast of Norway, were still green when the researchers uncovered them. Chlorophyll typically decomposes rapidly if it's exposed to light and oxygen, but sudden burial by the tsunami sealed off the material, say the researchers. Also, the acidity of the sediments was low because some shell fragments dissolved and released carbonate ions—another factor that preserved the chlorophyll.
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Weight redistribution from the Ice Age melt probably caused both.
"Dating a massive undersea slide"
Reminds me of a blind date 20 years ago...........
Where did the earthquake occur?
Crustal rebound. The same thing will save us when Antarctica and Greenland lose their icecaps.
Thanks.
Moss underneath and everything?
Study Sees North Sea Tsunami Risk
It was a catastrophe of apocalyptic proportions. An earthquake shook Norway's coast between Bergen and Trondheim about 8,150 years ago. The tremors ripped pieces of land the size of Iceland from shallow water and sent them crashing into the deep sea. Like a stone thrown into a pond, the landslide produced ripples of waves that spread at the speed of a train -- powerful tsunamis racing across the North Sea. Along the beaches of Scotland the waves were up to six meters (20 feet) high. Geologists have discovered a ravaged Stone-Age site there.
"Moss underneath and everything?"
How did you know her last name???
See post #8. I think that may be it. Apparently the land is still 'rippled' in Norway from the quake I mentioned.
You dated her too, huh?????
*LOL*!
Shouldn't evidence of that tsunami still be present in modern England and Scotland?
Has erosion altered the landscape that much in 8100 years to erase all evidence of deposits?
bookmark ping-a-ling , & THANKS blam
I've read that there is still evidence...I just can't find where I read it.
Although we are in serious danger of hijacking this thread, I'll only say that I am having memories of that parody song:
Round, round, big and round
she's big and round
(beach boys riff)
Coulda been an SUV induced global warming event or a meteor strike or ....
Naw. See, on the Internet they always send ya' ancient history pictures ....
You know...from eons ago when their land masses were at least a 100 lbs lighter!!!
That return it???????
Bush's fault! Halliburton did it under orders from Cheney!
Redd Foxx once said that his 300 lb. wife thought he loved her, 'cause every time she got into bed, he rolled toward her.
It was a joke.
LOL. I liked Redd Foxx and Lamont.
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