By ROB WAUGH
Marine geophysicists from the University of New Hampshire have found huge ‘bridges’ across the Mariana trench, which cross the trench about a mile above the bottom.
The bridges are created when mountains on the sea floor are pulled into the earth’s crust by enormous geological forces. The mountains, sticking up from the Pacific ocean plate, form ‘bridges’ as the the Pacific plate disappears into the earth’s crust under the neighbouring Philippine plate.
‘It wasn’t common knowledge these bridges occurred at all,’ said James Gardner, a University of New Hampshire scientist who found the structures.
One of the bridges was detected in low resolution in the Eighties, but Gardner’s team has made three more sightings, according to OurAmazingPlanet.
Some of the bridges rise up to 6,600 feet above the trench, and are up to 47 miles long. The scientists used a multi-beam echo sounder to map the area. Gardner says that there might be life on the ‘bridges’ – adapted to harsh, freezing conditions and pressure up to eight tons per square inch.
‘I would certainly expect Dutton Ridge and the others to have different fauna and flora than the trench floor, because they stand about 2 kilometers [1.2 miles] higher,’ Gardner said. ‘But the extreme depth would make it hard to monitor the biology or seafloor currents in the area.’
A ‘hydrographic’ ship from the U.S. Navy recently mapped the Marianas trench from north to south using a ‘multibeam echosounder’, a standard device for mapping the ocean floor.
The ship, associated with CCOM, the Centre for Coastal and Ocean Mapping at the University of New Hampshire, mapped the whole of the Marianas Trench to a 100m resolution.
‘The instrument allows you to map a swath of soundings along the line of travel of the ship,’ said Dr Jim Gardner to the BBC. ‘It’s like mowing the grass.’ The researchers are examining the process of how underwater mountains are ‘pulled under’ another tectonic plate.
‘Our data shows they are getting really fractured,’ said Dr Gardner, ‘As soon as the Pacific Plate starts bending down, it cracks that old, old crust. It cracks right through the seamount. They get splintered and whittled away, then pulled under.’