220 DISCOVERY REPORTS 



These depths were obtained on a zig-zag Hne of soundings run in March 193 1 from the 

 eastern end of the Burdwood Bank to the Shag Rocks. During this traverse fifty-three 

 soundings of under 2000 m. were obtained, and of these, four were under 500 m., 

 nineteen under 1000 m., and forty under 1500 m. A subsequent Hne of echo soundings 

 during the season 193 1-2, running from south to north across this Hne in about 54° W, 

 gave six more soundings under 2000 m., one of which was under 1500 m. This hne 

 crossed the earHer Hne in about 54° S, where the soundings were in close agreement, 

 and continued north to 53° S. From here the Hne was run in a north-easterly direction 

 to approximately 51" 30' S, 49° 00' W, where the course was altered to south. 



Fig. I. Key chart showing the areas covered by Charts 1-7, and positions 

 of sections in Figs. 2-4. 



This southerly traverse along the 49th meridian crossed two of our earlier lines of 

 soundings, the first in about 53° 20' S, and the second in about 54° 30' S. Unfortunately 

 about 10 miles north of the former line the oceanic echo-sounding machine broke down 

 and soundings were not resumed for about 30 miles, so that the confirmation of the 

 depths recorded in the previous year was not possible. On the second line, however, the 

 agreement was good. 



Fig. 3 b (p. 226) shows a section across the Scotia Sea which is based on this line of 

 soundings. From it can be seen very clearly both the Tierra del Fuego — Shag Rocks 

 ridge and also the connexion, double at this point, between the South Orkneys and 

 Clarence Island. 



