68 DISCOVERY REPORTS 



ridge.i Farther to the west the complexity of the ridge connecting the South Orkneys with Clarence 

 Island is not very clearly shown, and a ridge, the existence of which must be regarded as doubtful, 

 is shown as running north-west for some 220 miles from Elephant Island; our soundings here do 

 show a small area less than 2000 m. in depth some 75 miles from Elephant Island in the same 

 direction, but there appears to be little evidence in support of the connexion of this area with 

 the island. In the Bransfield Strait the outline of the comparatively deep basin is not well shown. 

 In part this may be due to the small scale of the chart but it would also appear that the compilers 

 have overlooked the data published in pi. xlvii of our previous report. 



Certain banks shown on this chart are referred to as 'seamounts', a term which does not appear to 

 have been among those considered by the International Committee of 1936 (see p. 60). It appears, 

 however, in the terminology of submarine topography given by Sverdrup, Johnson & Fleming 

 (1942, p. 25), where a 'seamount' is described as 'an isolated mountain-like structure rising from the 

 ocean bottom '. In the present report the original term ' bank ' has been retained for all such features. 



DETAILED ANALYSIS OF THE SECTORS OF THE SCOTIA ARC 



TIERRA DEL FUEGO TO THE SHAG ROCKS 



In pi. xlv in our previous report the contours of the Arc were drawn to fit as well as possible the 

 data then available. These contours need considerable modification in the light of subsequent 

 soundings, and it therefore seems worth while to examine the various sectors of the Arc as before in 

 some detail. 



Very many more soundings have been taken in the vicinity of the Burdwood Bank, which is an 

 accepted feature of the Arc, with the result that the area of the bank, of less than 250 m. (137 fm.) 

 in depth, has been considerably reduced. Six lines of soundings were run across the bank between 

 1932 and 1938, one at the western end, two in the middle and three, in a southerly direction from 

 Cape Pembroke, at the eastern end. A series of soundings, crossing the north-west corner of the bank, 

 was also taken in 1936, in 54'^ S, as part of a line of soundings from South America to South Georgia. 

 A further line, approximately south-east by south from Cape Pembroke, was of great value in the 

 determination of the eastern limits. North of the bank these various lines have proved beyond doubt 

 that there is relatively deep water between the bank and the Falkland-Patagonian shelf. A large area 

 with depths greater than 500 m. (273 fm.) is found here and extends considerably west of the longitude 

 of the Falklands. Depths of more than 1000 m. (547 fm.) extend along almost the whole northern 

 side of the bank, the western limit of the contour being in, approximately, 60° 15' W. The 2000 m. 

 (1094 fm.) contour can now be shown to lie in about 58° 45' W and a corresponding alteration in the 

 3000 m. (1641 fm.) contour can also be made in view of this fresh evidence. 



The separation of the Burdwood Bank from the continental shelf would now appear to be firmly 

 established and the profile running south from Cape Pembroke across the Scotia Sea, which we have 



1 The soundings taken by the 'Waher Rau' and already mentioned in the footnote to p. 66 indicate that there is some 

 doubt about the existence of the Bart Bank, at any rate in the position at present assigned to it. The information available 

 from Stocks's map shows that the 'Walter Rau' obtained at least three soundings exceeding 3000 m. (1641 fm.) at or near 

 the position of the bank, and what is perhaps m.ore important, obtained further deep soundings between here and the Orkney 

 shelf. This latter evidence strongly supports our contention that if the Bart Bank does exist at or near the position now shown 

 for it, then it must be an isolated feature. 



There is little information about this bank. It first appeared on British Admiralty Chart N0.3176 in 1941 and the authority 

 for its insertion was a Norwegian chart dated 1938 (private communication to the author from the Hydrographic Department 

 of the Admiralty). The only other references to the bank which can be found appear to be on U.S. Chart No. 2562 (referred 

 to above) and a very brief statement in the U.S. Sailing Directions for Antarctica, 1943 (p. 259) of the position and depths 

 found. No authority is quoted in support of this information. 



