94 DISCOVERY REPORTS 



76° S, west of the meridian of 179° E, and there is a serious gap to the east of the Pennell Bank. Here, 

 between the 500 m. (273 fm.) and 3000 m. (1641 fm.) depth contours there is only one sounding in the 

 distance of about 100 miles which separates the lines of soundings taken by the ' Discovery II ' and the 

 ' Bear of Oakland '. North of the Ross Barrier there is a large area, triangular in shape, where there are 

 no soundings between the series obtained by the 'Discovery IT in 1936. 



Few soundings have been obtained oflF the coasts of Victoria Land. Such as have been taken, 

 however, suggest that this is a region of considerable interest, for in many places where the land slopes 

 steeply down to the sea the bottom appears to descend rapidly to the 500 m. (273 fm.) contour or 

 below. There is little or no shallow water for any distance from the coast, and just south of Terra Nova 

 Bay (in approximately 73° S) a depth of 350 fm. (640 m.) is shown on British Admiralty Chart No. 3206 

 approximately zh miles from the land. From the same source another sounding, near Cape Roberts 

 (in approximately 77° S), shows a depth of 313 fm. (572 m.) only 3 miles off-shore. OflF the Drygalski 

 Ice-tongue existing soundings indicate the existence of a narrow trench, with a depth of slightly over 

 1000 m. (547 fm.). 



Despite these gaps it is probable that the main features of the bottom relief of the Ross Sea are 

 now tolerably well known ; yet the results of our hydrological and biological observations made in 

 the southern part of the sea are difficult to reconcile with our present interpretation of the bottom 

 topography. 



Deacon (1937, p- 115) in his remarks on the hydrological observations in this area supports the 

 conception of a relatively shallow ridge, at depths less than 500 m. (273 fm.), between Cape Adare and 

 King Edward VII Land, but he also suggests that there can be no channel through this ridge near the 

 coast of Victoria Land. We have already shown that a continuous ridge at this depth across the Ross 

 Sea almost certainly does not exist, but soundings in the gap indicate that the depth here is generally 

 100 to 150 m. (55-82 fm.) less than that of the area immediately to the south-west. This rise from the 

 moderate depths of the southern part of the Ross Sea is probably sufficient to prevent the escape to 

 sea of the cold bottom water, but on the present evidence from soundings it is difficult to agree with 

 Deacon's suggestion that there is no deeper channel along the coast of Victoria Land. There can be 

 little doubt now that such a channel can be traced as far north as the latitude of 73° S, and although 

 there are only a few soundings north of this point it seems improbable that there can be any shallow 

 connexion between Victoria Land and the 500 m. bank between here and Cape Adare. 



KERGUELEN-GAUSSBERG RIDGE 



The Kerguelen-Gaussberg ridge extends over a wide area, in a south-easterly direction from the 

 island of Kerguelen to the Antarctic Continent. Rising on the average some 2500 m. (1367 fm.) above 

 the general level of the ocean bottom on either side, the ridge separates the Atlantic-Antarctic and 

 Australian-Antarctic basins. It exerts a profound influence on the hydrology of these regions of the 

 Southern Ocean. 



Between Kerguelen and Heard Island the ridge is comparatively steep-to on the western side and 

 slopes away to deep water more gently in the east. South of latitude 55° S these conditions are 

 reversed and it is on the eastern side of the ridge that the slopes become abrupt. From this latitude 

 to that of 60° S the topography of the bottom is varied and there are two well-marked shallower areas. 

 One of these is Banzare Rise, on the western side of the main ridge, which was discovered by the 

 B.A.N. Z. Antarctic Research Expedition in 1929. The minimum depth determined by them, during 

 two crossings of the rise, was 351 fm. (642 m.), in 58° 50' S, 77° 44' E. The U.S. Chart of Antarctica 

 (No. 2562) and the Australian map of Antarctica both show a sounding of 103 fm. (188 m.) on the 

 Banzare Rise; the source of this information, however, is not known to us. 



