SOUNDINGS TAKEN DURING THE DISCOVERY 

 INVESTIGATIONS, 1932-39 



By H. F. p. Herdman, m.Sc. 

 (Text-figs. 1-19, Plates XXIII-XXXI) 



INTRODUCTION 



THE oceanic soundings taken by the R.R.S. 'Discovery', 'Discovery 11' and 'William Scoresby' 

 fromi926to 1932 have been dealt with in a previous report (Herdman, 1932). Most of the soundings 

 in that period were in the West Antarctic region, and the report included descriptions of the sounding 

 equipment then in use, an account of the Scotia Arc and its significance, comments on the bottom 

 topography of the Scotia Sea and neighbouring regions, and bathymetric charts of the Scotia Sea, 

 the vicinity of South Georgia, and the Bransfield Strait and adjacent waters. Between 1932 and 1939 

 many thousands of additional echo soundings (far more than in the period before 1932) were taken by 

 the ' Discovery II ', together with a small number of Lucas soundings taken on station by the ' William 

 Scoresby' and by the 'Discovery II' when her deep-water echo-sounding set was temporarily out of 

 order. These new soundings are spread over nearly all parts of the Southern Ocean (see Text-fig. 18, 

 p. 89); they greatly amplify the previous soundings in the West Antarctic region; and they throw 

 much new light on some areas of special interest. Owing to the dispersal of the Discovery Committee's 

 staff during the years of war this very large accumulation of data could not be analysed until now. 



Although many unpublished oceanic soundings are available, the time has hardly come for a new 

 bathymetric chart of the Southern Ocean. Nevertheless, the data justify a review of the bottom 

 topography associated with the Scotia Arc, an account of soundings taken during various hydro- 

 graphic surveys, and an account of certain localities in which the bathymetric features are of some 

 oceanographical or geological significance. When deep-sea echo soundings are undertaken on a large 

 scale, especially in regions of much bad weather, many practical difficulties arise which have not been 

 adequately dealt with in previous publications. In the following pages, therefore, and in Appendix I 

 considerable attention is given also to technique ; and the interpretation of individual soundings and 

 continuous records is also discussed. 



The present report is based on the Discovery Committee's data, but in the preparation of the 

 contour charts soundings from all available sources have been used, especially in the Ross Sea area, 

 where a considerable number of echo soundings were taken between the years 1933 and 1935 by the 

 second Byrd Antarctic Expedition. In the Scotia Sea area and in the Bransfield Strait we have used the 

 full results of the ' Meteor ' sounding programme, which agree well with our own observations. With 

 these exceptions the number of soundings from other sources in the areas concerned is almost negligible 

 and in most instances adds little or nothing to the information obtained from our own observations. 

 In fact, our intensive sounding programme has shown that either the position or depth of some of the 

 earlier soundings from other sources is quite unreliable. 



Soundings taken by the ' Discovery II ' may be roughly classified in three main groups: (a) Routine 

 oceanic soundings, normally taken every hour when on passage, at every scientific station and when 

 steaming between stations, (b) Soundings taken during hydrographical survey work, and (c) Special 

 soundings taken on the occasions when a submarine ridge, bank or other interesting feature of the 

 ocean floor was being crossed. The routine soundings (a) were usually obtained under way at normal 



