194 



STATIONS WS97G 



SEA MILES I 



OFFSHORE I'S 



O- 



100- 



200- 



300- 



400- 



WS977 

 I 



DISCOVERY REPORTS 



WS978 



Fig. 40. Distribution of dissolved oxygen. Section off Walvis Bay, 6-8 March 1950, survey I. 



Positions of stations are shown in Fig. 1. 



STATIONS 

 SEA MILES 

 OFFSHORE I7S 

 O- 



WSIOSfa 



WSI055 



WSIOS3 

 I 



100 



300- 



400 -L 



WSIOSI 



I 



WSI050 

 I 



Fig. 41. Distribution of dissolved oxygen. Section off the mouth of Orange river, 21-24 September 1950, 



survey II. Positions of stations are shown in Fig. 2. 



to trace its origins let us first examine the waters at subsurface depths adjacent to the continental 

 shelf, from which the upwelling occurs. 



If we plot the dissolved oxygen content against temperature for survey I in the 200-600-m. layers 

 (Fig. 45), we see that the stations closer to the continental shelf and to the north of the region have 

 the lowest oxygen content, while those farther offshore and in the south have a higher oxygen content. 



