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Science Frontiers ONLINE No. 42: Nov-Dec 1985 |
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Sand dunes 3 kilometers down
Side-scan sonar systems are excellent for mapping the major geological features of the sea floor. Some of the scenery revealed by this sonar challenges conventional geological wisdom. To illustrate, the British ship Farnella has been mapping the floor of the Gulf of Mexico with its GLORIA II side-scan sonar. Hundreds of new salt domes, submarine channels, and landslides have been recorded. A big surprise was the discovery of large fields of sand dunes in 3000 meters of water. Similar dune fields were found in the Pacific in 1984. G. Hill, of the U.S. Geological Survey has ventured, "There's something going on in deep water that people just aren't aware of. " ("A Systematic Sounding of the Sea Floor, " Science News, 128:191, 1985.) (At issue here is how sand dunes are formed in such deep water. Are they the consequence of colossal bottom currents, perhaps set in motion by huge earthquakes of some other natural catastrophe ? Is it possible (gasp!) that the dunes were not formed under water at all ? The area involved also boasts salt layers and submarine channels and canyons, both of which are not well-explained. WRC)