66 DISCOVERY REPORTS 



noticeable in the region of the Burdwood Bank, around South Georgia, north-west of the South 

 Orkneys and north-east of Elephant Island. The slopes off the South Orkneys are among the steepest 

 we have met ; they are certainly among the steepest slopes of any length from which we have been able 

 to obtain a very good record, and we were fortunate to have fine weather in which to run the recorder 

 when leaving Coronation Island, in a northerly direction, in February 1937. The record (see PI. XXVI, 

 fig. i) covered 11 miles of the bottom, with a steady fall from the anchorage of 25 fm. (46 m.) to the 

 edge of the shelf in 148 fm. (271 m.) and then an abrupt descent to a depth of 1514 fm. (2769 m.). The 

 profile constructed from this record is shown in Text-fig. 13 a with the vertical scale exaggerated 25 

 times and in Text-fig. 136 on the true scale. Soundings every minute were taken off the record to 

 construct the latter, and the average gradient northward from the edge of the shelf, as determined 

 graphically, is approximately 20°. The maximum slope here is approximately 25". 



Some shorter slopes of a similar magnitude have been observed on records taken in the channels 

 of the Palmer Archipelago, during the surveys of the South Shetland Islands and in various 

 channels leading seaward from Magellan Strait, but their length was generally only a fraction of 

 a mile, and since the angle of approach to the contours was usually unknown, accurate analysis 



i 



lOOQ 



Fig. 13. Slope of bottom to the north, from Coronation Island, South Orkneys. Positions of soundings are marked 

 on the horizontal scales, (a) Vertical scale, x 25. {b) True scale, based on 65 depths from continuous record. 



has not been possible. In certain isolated instances, however, the density of soundings is such 

 that a few contours can be drawn and the slopes which occur in these areas will be discussed m 

 more detail in a later section of this report which deals with soundings taken during hydrographical 

 surveys. 



In these general remarks on the Scotia Arc it will be advisable, perhaps, at this point, to refer to 

 some recent bathymetric charts which include this area. Stocks (1937), in one of a series of bathy- 

 metric charts of the Atlantic Ocean included in the ' Meteor ' Reports, shows the contours of the 

 eastern end of the Arc on a large scale. The western limit of this chart is the meridian of 30° W and 

 the contours should, of course, be studied in conjunction with those of the area to the west; unfortu- 

 nately, this chart, which covers the remainder of the Scotia Sea, was not published in Germany until 

 1941 and we have not, as yet, been able to obtain a copy.^ The 'Meteor' soundings have, however, 

 been published as lists of soundings (Maurer & Stocks, 1933) and we have used these in the compilation 

 of our bathymetric chart. The depths obtained by the 'Meteor' which were shown on our original 

 chart were only a small selection of soundings which had been supplied to the Hydrographic 

 Department of the British Admiralty shortly after the return of the vessel. 



In the eastern area which comprises the Arc, Stocks has based his contours mainly on one line of 

 soundings obtained by the 'Meteor' in 1926 and on a selection of our soundings (presumably those 

 which were published with our previous report or which have appeared in our Station Lists) together 



" Since this was written we have obtained a copy of this chart. No contours are shown and most of the information was 

 already known to us, but some hitherto unpublished soundings, taken by the whaling factory ship ' Walter Rau ', provide 

 valuable confirmation of our interpretation of the topography of the bottom in the neighbourhood of the South Orkney 

 Islands. 



