SOUNDINGS TAKEN DURING THE DISCOVERY IN VESTK; AT I ONS, 1932-1939 85 



All these channels are narrow and comparatively deep, with an extremely irregular bottom topo- 

 graphy. At the northern end of Pedro Sound a maximum sounding of 232 fm. (424 m.) was obtained 

 4 cables oflF-shore, in a position where the width of the sound was only 1-15 miles. In the Cockburn 

 Channel depths often exceeded 300 fm. (549 m.) and the maximum sounding of 377 fm. (691 m.) 

 which was obtained here in October 1932 was in a position where the channel is barely 3 miles in 

 width. The bottom here is extremely varied, and when the continuous record was taken, in November 

 1934, slopes of 10-15° were common; in one place the depth increased by 132 fm. (241 m.) in 3 min., 

 which is equivalent, approximately, to a slope of 16°. 



The entrance to the main strait by way of Otway Bay and Sea Shell or Abra Channel is very similar to 

 those already described. The seaward entrance is shallow but once among the numerous islands 

 through which the channel runs depths greater than 400 fm. (732 m.) were found over a considerable 

 distance. The maximum sounding obtained by the 'Discovery II' in December 1933 was 478 tm. 

 (784 m.), at a point where the channel is barely 2 miles in width. It is probable that the bottom here is 

 also very varied but, as already stated, we were not able to obtain a continuous record on this passage. 



SOUNDINGS OFF ANTARCTICA IN THE MERIDIAN OF GREENWICH 



Between July 1938 and March 1939 a series of cruises was made by the ' Discovery II ' to the south 

 and west of Cape Town (see Text-fig. 18, p. 89). By these cruises throughout winter and summer, 

 over the same area, it was hoped to obtain valuable information on the seasonal changes across the 

 Southern Ocean, between South Africa and the ice-edge. On each cruise the ship steamed to the 

 latitude of 40° S, on or near the Greenwich meridian and then southward as far as possible. She 

 then worked across the ice-edge to the meridian of 20° E and returned to Cape Town approximately 

 on this meridian. Routine soundings were taken on all cruises, since the course was never quite the 

 same for each cruise, and the recorder was used whenever possible. In the first five cruises the 

 'Discovery 1 1' was stopped by pack-ice far from the Antarctic Continent; but in the sixth cruise 

 (January 1939) she reached a point some 19 miles north of the 'barrier', and on the seventh (in early 

 March) she reached the barrier and sighted land. 



On the sixth cruise a continuous record was begun in 68° 55-2' S, 02° 05-3' E at a depth of 2121 fm. 

 (3859 m.), and for a distance of 42 miles southward there was a slight but steady upward slope, not 

 exceeding 2°, which reached a minimum depth of 846 fm. (1547 m.) in approximately 69° 35' S, 

 02° 05' E, 3 miles north of the ice-edge. In this last 3 miles the bottom became more irregular, with 

 some increases in depth, but had begun to shoal again shortly before the ice was reached in 69° 37-9' S, 

 02° 07-8' E. Here the depth was 1052 fm. (1924 m.), and from the soundings obtained 18 miles south 

 of this position on the next cruise it would appear that this steady rise continues for some miles and 

 that there is finally a much steeper slope up to the continent. 



On the last of the repeated cruises (in March 1939) the barrier was first sighted in 69° 15' S, 

 00° i2-i'E and the sounding close alongside the northernmost ice-cape was 11 14 fm. (2037 m.). 

 Continuous soundings had been commenced some miles north of this point, in a depth of 15 18 fm. 

 (2776 m.), and records were obtained along the barrier to a position in 69° 05' S, 04° 30' E, a distance 

 of 140 miles. The recorder was run for 28 hr. during two days and the track of the ship is shown in 

 Text-fig. 16 (p. 86). 



The depth shoaled fairly rapidly towards the barrier in this longitude, the slope of the bottom from 

 seaward averaging gV, and this slope continued towards the land. In 69° 58-2' S, 01° 31-0' E the ship 

 was probably about 5 miles from land and the sounding was 105 fm. (192 m.). As will be seen from the 

 track in Text-fig. 16 the course then lay to the north-east and the depth increased rapidly. When the 



