Monday, March 05, 2007

Dear 'Liza, dear 'Liza

Scientists Find Gaping Hole At Bottom Of Sea



A gaping hole in the Earth's surface three kilometres beneath the ocean is to be probed by scientists.

Researchers have discovered thousands of square kilometres of seafloor uncovered by the Earth's crust in the middle of the Atlantic, which they describe as being like an "open wound".

Crust several kilometres thick would normally be there, but instead the mantle, the layer beneath the crust, has been left exposed.

Dr Chris MacLeod, of Cardiff University, described the find as a "startling discovery" and said it could even help us better understand global warming.

He said: "There are a few places around the world where we can see bits of mantle rock but none where we can have such direct access.

"It's very unusual to find a place where the earth doesn't have a crust and conventional theories have difficulty in explaining it."

The discovery was made at the exact boundary between the African and North American plates and Dr MacLeod said that the normal process of 'seafloor spreading' had somehow gone wrong.

He said: "Normally with the movement of plates, as has happened here, the space between them is taken up at first by the mantle which rises to the surface. It should then melt and form new crust, but for some reason that hasn't happened here. The plates are spreading but we are not seeing the crust."

Dr MacLeod, a marine geologist, will set off with other scientists on the research ship RRS James Cook. A 20-strong crew will use sonar to survey the seafloor and then use a robotic drill to pick up rock samples.

And Dr MacLeod believes that the research could revolutionise the way we understand plate tectonics.

He said: "We have to reconsider our ideas about basic plate tectonics. It is not quite as simple as the textbooks would have you think. They can't explain why there shouldn't be a crust in areas like this."

He also explained that though it is not directly related, this research could help us understand global warming and environmental change better.

He said: "We need to know the way that the basic engine of the earth works and this will allow us to do that. Everything is linked to that and I think this could be a step along the way to understanding the more specific problems like global warming."

The expedition which will cost US$1 million (£510,000) will be led by marine geophysicist Professor Roger Searle, from Durham University, and Dr MacLeod could not contain his excitement.

He said: "It's extremely exciting. We feel like the 19th century explorers of Africa, but we are 21st century explorers of the seafloor. It is completely new ground and we feel privileged.

"You hope to answer the questions that you came with and then to come back with an equal number of new ones. The only expectation is the unexpected."

Prof Searle, from Durham University’s Department of Earth Sciences, said: "This is probably the first area where the mantle has been observed extensively on the seafloor. It gives us a unique opportunity to study this enigmatic part of the Earth in detail.



"Our current theories suggest that as the tectonic plates separate, the mantle rises to fill the gap and, in doing so, partly melts."



The progress of the expedition - which sets sail from Tenerife and returns in April- can be followed online at www.noc.soton.ac.uk/gg/classroom@sea/JC007/

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