32 DISCOVERY REPORTS 



present suggest that only by this indirect route does the water flowing out of the Ross 

 Sea reach the cold region north-east of the sea. 



There are as yet insufficient data to show whether the Antarctic water that flows 

 northwards near the Kerguelen-Gaussberg ridge and the Balleny Islands curves back 

 to the south farther east and circulates in a clockwise direction. Such a possibility is 

 indicated by the receding of the isotherms and ice-limits towards the south, but the 

 changes may, on the other hand, be due only to a decrease in the strength of the north- 

 ward movements. Of the currents which carry water into the northern part of the 

 Antarctic Zone only the Weddell Sea current retains its individuality for any appreciable 

 distance ; the others merge with the main drift towards the east. 



The path of the main drift in the northern part of the Antarctic Zone is indicated by 

 the isotherms and isohalines in Figs. 6, 7, and 8. It does not flow due east but has 

 northward and occasionally southward movements of varying strength. The width of 

 the current and the extent of the Antarctic Zone are also subject to considerable 

 variations ; these are shown by the varying latitude of the Antarctic convergence in Fig. 4. 



In the Scotia Sea the convergence bends north, north-west, and then back to the east. 

 The north-westerly salient lies mainly to the north of the Scotia Arc (Herdman, 1932, 

 p. 214), and it seems to exist principally because there is a greater flow of bottom water 

 on that side of the arc : the warm deep water is forced to climb towards the surface 

 farther to the north-west, and the Antarctic water flows farther in this direction before 

 it can sink. The movement of the Antarctic water towards the north or north-west is 

 clearly demonstrated by the temperature and salinity distribution. 



Towards the western end of South Georgia the isotherms and isohalines bend south- 

 wards, suggesting that the surface water has a small southward movement. Such a 

 movement is possibly a final trace of the southward movement indicated so clearly 

 farther north by the Brazil current, which can itself be traced to within 300 miles of the 

 Falkland Islands (Klaehn, 1911, pi. 34). The effect of the southward movement on the 

 conditions round South Georgia causes the south-west coast of the island to be bathed 

 with water from the Bellingshausen Sea current, whilst the Weddell Sea current is held 

 offshore. 



North-east of South Georgia the isotherms, isohalines, and the convergence bend once 

 more to the north. This bend seems to be related in the same way as that east of the 

 Falkland Islands, to the influence of a greater movement of bottom water towards the 

 north-west outside the Scotia Arc. In this region the bottom water flows strongly 

 through the deep channel which leads past the comparatively shallow water north of 

 South Georgia, into the Argentine Basin (Plate XLIV). In the northward movement at 

 the surface, the Weddell Sea current approaches South Georgia and has a large influence 

 on the conditions off the north-east coast. The northward movement will be due in some 

 measure to the direct influence of the ridge and the presence of the island on the surface 

 and deep currents towards the east, but its great extent, and the fact that the cold salient 

 lies chiefly over the deep water north of the ridge, suggest that it exists mainly because 

 of the stronger bottom current outside the ridge. 



