DISCOVERY REPORTS 



" The sub-Antarctic Zone is in the region of constant westerly winds and the surface 

 water is moving eastwards with the West Wind Drift. This water is in continuous 

 movement round the southern ocean. The zone includes Cape Horn, the Falkland 



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Fig. 2. Contour chart showing the submarine plateau upon which South Georgia stands and covering the 

 main area of the 1926-7 plankton survey (after Herdman, 1932). 



Islands and that part of the Patagonian coast under the influence of the Falkland 

 current. It also just includes Gough Island and Tristan da Cunha." 



For the general distribution of these zones in the region under discussion see Fig. 4. 



" In the Antarctic region three distinct layers of water can be observed in the vertical 

 section. In the upper layer is the cold and poorly saline Antarctic water, below which 

 the salinity and temperature increase to a maximum in an intermediate layer ; while 

 deeper still, towards the bottom, the temperature, and also slightly the salinity, decrease 

 as a third layer is encountered. 



' The work of Dr O. Pettersson and J. W. Sandstrom has shown how polar influences 

 give rise to a circulation of water in the ocean and a system of layers such as has been 



