94 



DISCOVERY REPORTS 



In 8o° W five sets of observations have been made from the ice-edge northwards in 

 December 1933, March, September, October and November 1934, but on no occasion 

 were observations made north of 55 S. The latitude of the ice-edge varied very con- 

 siderably, being farthest south in March and farthest north in September. In the upper 

 layers of the warm deep water the silicate content decreased northwards from values 

 of approximately 4500 mg. in 68° S, in summer and early autumn, and of 3250 mg. in 

 64 S, in winter, to about 1 500-2500 mg. in 58-59°S in the sub-Antarctic zone. In the 

 neighbourhood of the Antarctic convergence practically no variation occurred except 

 for the month of November when the content was higher. At the depth of maximum 



A.C. 



LATITUDE 66 5 



STATION S 



sefs 



Fig. 26. Graph showing the variation of the silicate content from south to north at the depth of maximum 



temperature of the warm deep water in 8o° W. 



salinity the content was about 5000 mg. at the southern end of the line of stations and 

 about 4500-5000 mg. at 56 S. As the diagrams in Figs. 26 and 27 show, there is 

 insufficient evidence for a discussion of seasonal variation. 



The silicate content in the upper part of the warm deep water has been discussed by 

 reference to the content at the depth of maximum temperature of the layer, chiefly in 

 the Antarctic zone ; that at a greater depth is given by the content at the depth of the 

 salinity maximum of the current. 



In the Scotia Sea the content in the upper part of the current varied from 5500 mg. 

 to 2700 mg. from south to north, whilst around South Georgia values of 3500 mg. and 

 4500 mg. are recorded for the upper and lower portions of the current. Warm deep 



