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Wound” in seafloor to be probed

March 2, 2007
Courtesy Cardiff University
and World Science staff

Sci­en­tists plan to set sail next week to in­ves­t­i­gate a startling find­ing in the depths of the At­lan­tic: a large ar­ea, thou­sands of square kilo­me­tres wide, in the mid­dle of the ocean where the Earth’s crust seems to be mis­sing. 

A ridge snak­ing down the mid­dle of the At­lan­tic, shown in light-blue in this ocean floor map, is an ex­am­ple of a mid-o­cean ridge, a place where the Earth's tec­ton­ic plates—sec­tions of the crust—are grad­u­al­ly mov­ing apart. As they do, mag­ma rises up to fill the gap, some­times lead­ing to sub­ma­rine vol­can­ic erup­tions. The red ar­ea marks a sec­tion of the mid-At­lan­tic ridge where sci­en­tists say crust is mys­te­ri­ous­ly mis­sing from a wide swatch of the sur­face, ex­pos­ing un­der­ly­ing rock. (Im­age cour­te­sy GEBCO )


There, they say, the mantle—a deep lay­er of Earth, nor­mal­ly bur­ied un­der many ki­lo­me­tres (miles) of crust—is ex­posed on the seafloor, 3 km (1.9 miles) un­der­wa­ter.

It’s “like an open wound on the sur­face of the Earth,” said T. Chris Mac­Leod of Car­diff Uni­ver­si­ty, U.K. “Was the crust nev­er the­re? Was it once there but then torn away on huge ge­o­log­i­cal faults? If so, then how and why?” 

To an­swer some of these ques­tions, Mac­Leod, with a re­search team led by ma­rine geo­phys­i­cist Rog­er Searle of Dur­ham Uni­ver­si­ty, U.K., plans to set off on March 5 for the ar­ea, mid­way be­tween the Cape Verde Is­lands and the Car­ib­be­an. 

The voy­age is to be the in­au­gu­ral cruise of a new Bri­tish re­search ship, RRS James Cook. 

The team plans to im­age the seafloor us­ing so­nar, an in­stru­ment that meas­ures dis­tances by emit­ting sound waves and count­ing the time they take to re­flect off ob­jects and re­turn. 

The group al­so plans to ex­t­ract rock sam­ples from the sea­floor us­ing a robotic drill. These will pro­vide a rare op­por­tu­ni­ty to learn more about the mantle’s work­ings, the re­search­ers said.

The ex­pe­di­tion’s prog­ress can be mon­i­tored via a web link to the ship, here. The sci­en­tists en­cour­age the pub­lic, and es­pe­cial­ly school­chil­dren, to ask ques­tions of them dur­ing the ven­ture us­ing the e­mail link on the web­site.


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Scientists plan to set sail next week to invest igate a startling finding in the depths of the Atlantic: a large area, thousands of square kilometres wide, in the middle of the ocean where the Earth’s crust seems to be missing. There, the mantle—the deep interior of Earth, normally covered by crust many kilometres (miles) thick—is exposed on the seafloor, 3 km (1.9 miles) underwater. It’s “like an open wound on the surface of the Earth,” said T. Chris MacLeod of Cardiff University, U.K. “Was the crust never there? Was it once there but then torn away on huge geological faults? If so, then how and why?” To answer some of these questions, MacLeod with a team of scientists, led by marine geo physicist Professor Roger Searle of Durham University, U.K., plan to set off on March 5 for the area, midway between the Cape Verde Islands and the Caribbean. The voyage is to be the inaugural cruise of a new U.K. research ship, RRS James Cook. The team plans to image the seafloor using sonar, an instrument that measures distances by emitting sound waves and counting the time they take to reflect off objects and return. The group also plans to take rock samples of the seafloor using a robotic drill. These will provide a rare opportunity to learn more about the mantle’s workings, the researchers said. The expedition’s progress can be monitored via a live web link to the ship, here. The scientists encourage the public, and especially school children, to ask questions of them during the venture via the on-line e-mail link.