260 GENERAL AIR CIRCULATION. 



Behind Adelie Land the land rises in 30 miles to 1,000 metres ; and then in a series of 

 undulations to the magnetic pole. Near the Gauss Station Wild found that the land rises 

 to 1,000 metres in about 30 miles and Filchner concluded that a similar rise occurs at Prinz 

 Leopold Land. It is reasonable to assume therefore that at all these points on the coast 

 there is a rapid rise to the plateau. I therefore conclude that the plateau covers the whole 

 segment of the Antarctic between Cape Adare and the Weddol Sea, decreasing in height from 

 the Pole outwards, at first slowly and then fairly rapidly near the coast. We kiaow that 

 the edge of the plateau on the Ross Sea side is very steep and edged by a range of high 

 mountains. Amundsen has shown that this range of mountains is continued beyond the Pole 

 ill such a direction that it probably connects up with Graham Land or with Prinz Leopold 

 Land. As either is equally probable and makes little difference to our discussion I have 

 assumed that the great escarpment which we know runs from Cape Adare nearly to the Pole 

 continues towards Prinz Leopold Land. 



Thus the Antarctic is supposed to consist of two parts divided by this escarpment, as 

 indicated in figures 81 and 82. The area on the Pacific side of the _gi-eat escarpment, single 

 hatched in the figures 81 and 82, is supposed to be at sea-level or nearly so, while the 

 area on the Atlantic and Indian sides, shown in the same figures by cross hatching, is high 

 tableland, the highest region being near the South Pole. 



In figure 80 a section of the continent is shown along the 90" E. meridian which is 

 continued beyond the Pole as the 90° W. meridian. This section is shown in figiu'e 82 by 

 the thick line AB. From 50° S. latitude on the left of the diagram we have open water 

 to the Antarctic Circle just north of which the Gauss wintered. From the Circle the land 

 rises to the plateau, at first rapidly and then more slowly, the exact contour of the surface 

 is not known nor is it material to our qualitative discussion. The high land continues a 

 little way beyond the Pole when the rapid descent through the Queen Maud range of moim- 

 tains occurs. From this point to nearly 70° S. there is either barrier or land ice of no 

 great elevation. Near to 70° S. on this meridian the Belgica wintered and therefore sea is 

 known to extend fi'om about 70° S. towards the north. These features are reproduced in 

 elevation on figure 80. 



The diagram shows clearly how the pressure variation is supposed to be affected by this 

 distribution of land, but the following points should be noticed. On the Gauss side of the 

 plateau the pressure is lowest near to 60° S. in accordance mth the observations made by 

 the Gauss Expedition. From 60° S. towards the plateau the pressure at sea-level rises. 

 Over the plateau the pressme also rises, the highest pressm-e occurring just before the Pole 

 is reached.* Over the area at sea- level between the plateau and the Belgica'' s position there 

 is a well-developed anticyclone in the lower atmosphere and a marked cyclone in the upper 

 atmosphere. Thus in this diagram we have been able to combine the pressure distribution 

 shown in figures 78 and 79. 



We are now in a position to indicate the probable distribution of pressure at sea-level 

 and at 3,000 metres over the whole Antarctic, if the distribution of high and low land is 

 that assumed. 



* The remarks made above about the Imes in these diagrams which represent the pressure variation being 

 "reatly exaggerated must be borne in mind. Tlius the fact that one of the pressure lines runs nearly parallel to 

 the surface of the plateau does not mean that the pressure on the surface is nearly constant. The best inter- 

 pretation of the lines is that at any given UUjU the pressure varies in the same sense that the nearest pressure 

 line rises or falls. 



