148 DISCOVERY REPORTS 



Soundings. Most of the soundings taken in shallow water during the course of our 

 running surveys are shown in the plates accompanying this report, and some reference 

 is made to them in the descriptions of the individual islands. An interesting feature 

 revealed by these inshore soundings is the existence of a deep basin, formerly a volcanic 

 crater, between two of the islands in Southern Thule (see p. 179). 



The depths between the islands have not been investigated with any thoroughness, 

 but soundings of 589, 774 and 840 fathoms were taken between Visokoi and Candlemas, 

 of 681, 721, 966 and 1062 fathoms between Bellingshausen and Bristol, and 499 and 

 822 fathoms between Montagu and Saunders. More recently a continuous line of 

 soundings, taken across the bank between Candlemas and Saunders, showed a minimum 

 depth of 1 196 fathoms. These depths are all considerably less than those of the seas 

 surrounding the islands : to the west is a basin with over 2000 fathoms and with more 

 than 3000 fathoms in its centre, while in the east the mean level of the Southern Ocean 

 is found at depths of more than 2500 fathoms. It is thus evident that the islands are 

 connected by a low submarine ridge. 



The relief of the ocean floor in the neighbourhood of the islands presents features 

 of considerable interest. To the north of the group very deep soundings have been 

 reported by the ' Deutschland ' and by the 'Meteor', the former vessel having found 

 3068 fathoms^ (lat. 54° 27' S, long. 31° 7I' W) and the latter 3664 fathoms- (lat. 

 55° 12' S, long. 29° 13' W) and 4402 fathoms^ (about lat. 55° S, long. 28° W). At the 

 time it was taken the last of these was the deepest sounding known in the South 

 Atlantic. Immediately to the south of these great depths geological theory of former 

 land connections postulates the existence of a shoal or bank linking the South Sandwich 

 Islands with South Georgia, and one or two of the few soundings taken in this area 

 seemed to show that such a bank might be found. 



In 193 1, the succeeding season to that in which the islands were surveyed, we were 

 able to take a number of lines of echo-soundings, and though much still remains to be 

 done we believe that the principal features in the topography of the region are already 

 apparent. The results are shown in the chart in Fig. 3, which indicates the approximate 

 positions of the 1000 to 4000 fathom contours. It will be seen that the South Sandwich 

 Deep has been traversed at three points, and we are able to prove that it extends round the 

 eastern side of the islands far to the south of the position in which it was first discovered. 

 Probably it is continued as far as the Thule group, but its southern limits have not yet 

 been determined. We have in all fourteen soundings which exceed 4000 fathoms, the 

 greatest being 4421 fathoms. We are also able to show with some precision that a 

 connection, in the form of a narrow ridge, exists between the South Sandwich Islands 

 and South Georgia, and it seems probable that the greatest depth on this ridge does 

 not exceed 1500 fathoms. 



The line of echo-soundings between Candlemas and Saunders Islands passes through 

 the widest gap between any two islands of the group. The line was continued to the 



1 Brennecke, Arch. Deutschen Seewarte, xxxix, p. 97, St. 52 (1921). 



^ Zeitschr. Ges. Erdkunde Berlin, lahrg. 1926, p. 234. ^ Loc. cit. supra, pp. 225, 274. 



