Abstract

Report of a meeting jointly sponsored by the Marine Studies Group of the Geological Society and the Challenger Society for Marine Science held at Burlington House on 1 February 1989.

T. J. G. Francis, the convenor, opened the meeting by briefly summarizing the development of the GLORIA (Geological Long Range Inclined Asdic) long range sidescan sonar at the Institute of Oceanographic Sciences since the mid-nineteen sixties. GLORIA has established itself in the nineteen eighties as the ideal tool for surveying Exclusive Economic Zones (EEZs). GLORIA surveys were carried out for 241 days in 1988 from two different ships, 140 of which were spent surveying the United States EEZ with the U.S. Geological Survey. By the end of 1988, some 13 million km2 of ocean floor has been surveyed, which is about 4% of the ocean deeper than 200m. The scale of USGS activity with GLORIA was equivalent to all UK deep Ocean geology and geophysics.

R. C. Searle (IOSDL, Wormley) spoke on the contribution of GLORIA to understanding mid-oceanic ridge tectonics. After reviewing a wide range of observations from the Atlantic, Pacific and Indian Oceans, he reported the results of the recent survey of the whole of the Easter Microplate camed out from RRS Charles Darwin last November. This revealed for the first time the complex plate boundaries, spreading fabric and associated propagating rifts and transform faults of the whole of this unusual feature.

D. Twichell (USGS, Woods Hole) spoke about the integration of digital bathymetry (SEABEAM) and sidescan (GLORIA) data with particular reference to the Gulf of Mexico. Gridding of the two data sets was done on the USGS Mini Image Processing System (MIPS). Since the sidescan backscatter

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