March 7, 2007

The Case of the Missing Crust

Scientists embark on a voyage to study a gash in the Earth's crust

By Vickie An

It’s a mystery that has the scientific community stumped. Five years ago, researchers discovered an area in the Atlantic Ocean seabed where a chunk of the Earth’s outer layer, or crust, is missing. A thick layer of dark green rock usually found deep inside the planet in the Earth’s mantle, lies exposed.

The crust, mantle and core are the three main layers that make up the planet. The mantle rests between the crust and the core, the hottest and innermost layer.

On March 2, a team of 12 British scientists set off on a six-week mission aboard the research ship, RRS James Cook, to investigate the hole in the crust. The ship departed from the Canary Islands, which are located off the coast of Africa. It will take the team about a week to reach the site of the gash.

A Look Inside the Earth

The hole is located about 2,300 miles southwest of the Canaries. It is about three miles below sea level and is believed to be more than 30 miles long and more than 30 miles wide. Scientists suspect that there are other nearby gaps. “It is like a window into the interior of the Earth,” says geophysicist Bramley Murton, who is part of the expedition.

The site where the hole is located forms part of a ridge of undersea volcanoes where two of the plates that make up the Earth’s surface meet. The plates are constantly moving and shifting. When the plates shift away from each other, lava rushes up from the mantle to fill the gap and form a new crust. But this did not occur in the area where the hole is located.

The hole is providing researchers with a rare opportunity to study what’s beneath the Earth’s surface. Once arriving at the site, the team will use a special robotic device named Toby to film the area and retrieve samples of the exposed mantle. One of the mission’s lead researchers, Roger Searle, said the team hopes to investigate everything from the chemistry of the oceans to how the Earth’s surface behaves under the sea.

News Image: credit - NERC

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