UNDER CURRENT 



EASTERN BOUNDARY 

 CURRENT 



MAIN UPWELLING 



SECONDARY 

 UPWELLING 



Schematic View of Coastal Upwelling. When favorable winds exist, blowing 

 toward the equator, the earth's rotation produces an offshore Eckman drift of 

 the upper ocean layers along the coast. This drift in turn produces an upwell- 

 ing of colder, deeper waters near the coast, often a narrow band 10 to 15 km 

 wide. The rich nutrients of the upwelled deeper water cause a rapid growth in 

 the plankton population which results in a rich feeding ground for fish. This 

 phenomenon is significant because an estimated 50 percent of the world's fish 

 supply comes from major upwelling areas. 



Woods Hole Oceanographic Institution completed the first half of its 

 survey of the Southeast Atlantic Margin from South Africa to Zaire 

 in 1972. In January 1973, the ship began the second half of this 

 survey, which will be completed later in 1973 with some measure- 

 ments as far north as Portugal and as far west as the Mid-Atlantic 

 Ridge. These last sets of measurements will enable scientists to tie 

 the results of this survey to those of a complementary survey of the 

 continental margins of the southwest Atlantic off the east coast of 

 South America, which was also initiated in 1972. Scientists from 

 institutions in many European, African, and South American 

 countries participated in both surveys. 



Site surveys for the Mid-Atlantic Ridge Study were initiated in 

 1972, conducted in large part by United States and French institu- 

 tions, with additional aid from institutions in Canada, the United 

 Kingdom, Iceland, and Portugal. In the Pacific, a comprehensive 

 Nazca Plate survey was launched off the northwest coast of South 

 America. This survey is concentrating on the active margins of the 



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