A detailed portrait of the Southwest Indian Ridge (SWIR)--the boundary between the slowly spreading Antarctic and African plates--reveals the steepest underwater cliff ever recorded and may shed new light on the origins of primitive life forms, John Madsen, University of Delaware geologist, reported today at the American Geophysical Union meeting in San Francisco
Madsen is part of a multinational, marine geophysical investigating team, called InterRidge, using remote sensing devices to map the SWIR's largely uncharted waters. In February and March 1996, InterRidge scientists spent 48 days aboard the R/V Knorr operated by the Woods Hole Oceanographic Institution. The ship covered 10,833 nautical miles.
They charted an area 1,000 miles south of Africa's Cape of Good Hope and above the Antarctic, where glaciers begin to thicken into land mass, and they discovered a drop in the ridge that goes from 500 to 20,000 feet in only 10 miles. "It's the steepest change in elevation along the mid-ocean ridge that's been mapped any place on the globe," Madsen said.
The topographical maps they produced will help scientists understand the physical characteristics of the sea and ocean floor. Madsen said their work will be useful to the entire oceanographic community but especially to those studying the biological, seismological and geophysical aspects of the area.
"Some biologists believe life may have originated at hydrothermal vents beginning at 10,000 feet below the surface," he said. That far down, the ocean water is close to freezing and when the 650 degrees Fahrenheit hydrothermal flowing through the vents hits the 37-degree water, sulfide deposits are formed, which some scientists believe might hold the key to the beginning of life on this planet. "We'll be making maps of the sea floor for people interested in finding these vents," he said.
Madsen says that the early results of their research suggest unusual geologic activity and volcanic processes are occurring along the Southwest Ridge that need to be incorporated into the information already known about the global ridge system. The team has submitted two new proposals to the National Science Foundation for charting areas to the east and west of where they've already mapped.