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largely upon soundings taken during the Discovery Investigations (after Herdman, 1932). 



In the present paper we are concerned only with the Antarctic and sub-Antarctic Zones, 

 South Georgia lying some 250 miles within the former. "The surface layer of the 

 Antarctic Zone is composed of cold poorly saline water, which owes its low temperature 

 and salinity to the additions of fresh water which it has received from melting ice. This 

 cold water moves slowly northwards until it meets the surface water of the sub-Antarc- 

 tic Zone, which is more saline but warmer and lighter. The Antarctic water therefore 

 sinks below it. The line along which the cold Antarctic water sinks below the warmer 

 sub-Antarctic water forms the northern boundary of the Antarctic region." This line is 

 called the "Antarctic Convergence". "The depth to which the Antarctic surface water 

 extends increases very slowly from south to north and reaches approximately 250 m., 

 before it meets the sub-Antarctic water. 



