The USGS and the British Institute of Oceanographic Sciences (IOS) first surveyed parts of the U.S. East Coast continental slope between Georges Bank and the Blake Escarpment using GLORIA during October and November of 1979. That early survey gave Twichell and Roberts (1982) a new look at the overall geomorphic pattern of submarine canyons on the mid-Atlantic continental slope. They could see that many canyons extend only partially across the mid or lower slope. Therefore, some submarine canyons can be created on the continental slope, without connection to the shelf edge and independently of shelf or shallow water processes. That insight inspired other studies and led to major conceptual advances in the understanding of submarine canyon origins and growth.
The EEZ-SCAN survey of the U.S. East Coast areas took place from February to May 1987, using a much superior GLORIA system, which recorded the data in digital form rather than as analog photographic records. The 1979 images had been as tantalizing as they were effective; they provided a new, broad view, but commonly lacked enough contrast to show the details clearly. The digital processing techniques available eight years later produced much clearer images that could be readily manipulated and combined with other data, such as bathymetry.
In the spring of 1987, survey operations proceeded aboard R/V Farnella during five periods, each about twenty-five days in length, beginning off Georgia and working northeastward.
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