. Commercial fisheries review. Fisheries; Fish trade. Diagonal markings show area covered by new Aleutian Island sea- bottom maps. They cover about 400,000 square statute miles of seabed where thousands of earth- quakes are spawned each year. Almost 25 years of work went into their preparation. They were compiled from more than 275 hydrographic surveys by vessels of ESSA's Coast and Geodetic Survey between 1943 and 1964--among them, the "Pioneer," "Survey- or," "Explorer," and "Pathfinder," The maps cover the seabed adjacent to the Aleutian Islands from
. Commercial fisheries review. Fisheries; Fish trade. Diagonal markings show area covered by new Aleutian Island sea- bottom maps. They cover about 400,000 square statute miles of seabed where thousands of earth- quakes are spawned each year. Almost 25 years of work went into their preparation. They were compiled from more than 275 hydrographic surveys by vessels of ESSA's Coast and Geodetic Survey between 1943 and 1964--among them, the "Pioneer," "Survey- or," "Explorer," and "Pathfinder," The maps cover the seabed adjacent to the Aleutian Islands from Unimak Island on the east to submerged Stalemate Bank, 45 statute miles west of westernmost Attu Island. The area extends from a few miles south of the Aleutian Trench to about 350 statute miles north; it includes the southern portion of the Bering Sea and the submerged mountain range (Bowers Ridge) extending northward into the Bering Sea. Provides Knowledge About Geologic Forces The detailed portrayal of submarine topog- raphy of the island chain can provide better understanding of the geologic forces shaping the ocean floor in this seismically active area. It will enable seismologists to determine changes in the sea floor resulting from major earthquakes. The maps can prove valuable to scientists in associated disciplines--phys- ical and biological oceanography, geophysics, and commercial fisheries. Many features, such as the immense Aleu- tian Trench, are shown in greater detail than before. This trench parallels the arc about 75 miles to the south of the Aleutian Islands and has a maximum depth of over 25,000feet. Positions of the soundings within sight of land were obtained by standard visual fixes, positions of offshore soundings were located by electronic positioning devices. Depths were secured with echo sounders that create a continuous profile of the ocean floor. The six maps, on a scale of 1:400,000, may be ordered by number for 50 cents each from the Coast and Geode
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Keywords: ., book, bookcentury1900, booksubjectfisheries, booksubjectfishtrade
