82 DISCOVERY REPORTS 



BALLENY ISLANDS 



In the Discovery Committee's programmes hydrographic survey has been concerned mainly with 

 the Dependencies of the Falkland Islands, but when time and conditions permitted every opportunity 

 was taken to examine little known or badly charted land in other regions. Among the most important 

 of these miscellaneous running surveys was that of the three northernmost islands of the Balleny 

 Group. These islands, the more northerly of which is situated in about 66° 35' S, 162° 30' E, were, up 

 to 1936, very imperfectly known, and there was considerable doubt about their correct position. They 

 have been sighted on several occasions since their discovery in 1839 but, with the conditions of pack- 

 ice, fog and bad weather which normally obtain here, a close approach was not possible. 



In February 1936, while returning from the Ross Sea, the ' Discovery II ' found the Balleny Group 

 clear of ice. A running survey was begun and an attempt made to land on Borradaile Island, but with 

 the onset of thick weather it became necessary to abandon both the survey and the attempt to make 

 a landing. There were no signs of improvement in the weather on the following day, and with fuel 

 running low it was essential to continue on passage to Australia. Continuous soundings, however, 

 had been obtained for 8 hr. during the clear weather, representing a distance run of 47 miles, and 

 the tracks of the ship during this period are shown in Text-fig. ^b, p. 46. 



During the second circumpolar cruise of the ' Discovery II ', in 1937-8, a further attempt was made 

 to complete the survey of the Balleny Islands. Approaching the group from the direction of Adelie 

 Land, in January 1938, it was found that the northernmost islands were clear of ice, and as the weather 

 was fine the running survey was resumed at the point where it had been abandoned in 1936. On 

 this occasion the weather remained clear and it was possible to complete the circumnavigation of 

 Young, Borradaile and Buckle Islands. Pack-ice to the southward prevented us from reaching Sturge 

 Island, but the island was clearly visible at a distance of about 17 miles, and it was possible to fix its 

 position approximately with relation to the remainder of the group. As our circumpolar cruise was, 

 of necessity, being worked to a fairly rigid timetable, we were unable to remain at the Balleny Islands 

 for more than two days. In that time, however, the ship covered a distance of 145 miles in 29 hr. of 

 survey, and continuous soundings were taken throughout this period. As with the earlier work the 

 tracks of the ship are shown in Text-fig. 3 b, p. 46, together with an indication of the likely trend of the 

 more important depth contours. 



The Balleny Islands lie approximately in a line from north-west to south-east, and form the crest of 

 a narrow ridge rising abruptly from the southern end of the Macquarie Rise, which connects the 

 Antarctic Continent with Australia.^ The general level of the bottom near the islands varies between 

 2500 and 3000 m. (1367 and 1641 fm.), and on the western side the slopes up to the group are consider- 

 able. One of our lines of soundings crossed the ridge about 3I miles north of Young Island, and the 

 angle of slope from the west was 13^°. So far as can be ascertained at present Young Island is steep-to 

 on both sides, and the slopes up to the land from 2000 m. (1094 fm.) correspond in the west to that 

 determined north of the island. To the east the slopes are much less, and from one of 11° at the 

 northern end decrease steadily to 6° off Cape Douglas. 



1 On the U.S. Chart of Antarctica (see p. 67) a possible connexion between New Zealand and the Macquarie Rise is also 

 shown, the link having been based, apparently, on one sounding of 1244 fm. (2275 m.). From a close examination of our lines 

 of soundings in this area and a study of the hydrological data, it is not possible either to confirm or deny the existence of such 

 a link, although the evidence from the soundings would tend to show that this sounding is more likely to be an isolated peak. 

 Deacon (1937, p. 114), in his. discussion of the distribution of the bottom water, considers that the hydrological conditions 

 existing in the deep basin of the Tasman Sea may be due either to the basin being shut off by a ridge, or caused by the rugged 

 nature of the bottom topography in this region. On the evidence now available it appears, therefore, that the existence of 

 a connexion between New Zealand and the Macquarie Rise is doubtful. 



