ANTARCTIC BOTTOM WATER: MOVEMENTS 115 



Ross Sea. The lowest bottom temperature measured in section 14 was 0-09° C. at a depth of 

 3 500 m. , and the properties of this water are such as may result from the mixing of the coldest 

 bottom water found in section n,— 0-19° C. at 3500 m., with warm deep water. It is how- 

 ever impossible to arrive at any final conclusions with regard to this region until 

 observations have been made in the channel which is indicated at the southern ends of 

 sections 12 and 13, and in the region between the Balleny Islands and Cape Adare; 

 owing to our observations being made in winter these localities were quite inaccessible. 



Although the temperature and salinity distribution in section 14 shows that no cold 

 poorly saline bottom water sinks from the Ross Sea, the water between 65 and 70 S has 

 a slightly higher oxygen content than that in the neighbourhood of the Antarctic Con- 

 tinent south of Australia. The difference is, however, not more than 0-07 cc. per litre, 

 and since the observations in the two localities were not made in the same year (the 

 southern part of section 14 in 1934, and the observations south of Australia in 1932) 

 it is not large enough to be regarded as contradictory to the evidence from temperature 

 and salinity. Larger differences were noted between sections 5 and 6 in the Atlantic 

 Ocean (see p. 112), and there is good reason to believe that the oxygen content of 

 the water in the eastward current from the Weddell Sea varies considerably from season 

 to season and perhaps from year to year. 



The soundings made so far in the Ross Sea (Bathymetric Chart, American Geo- 

 graphical Society, 1931) show that the greater part of the sea, which has a depth of 500- 

 1000 m., is shut off from the open ocean to the north by a relatively shallow ridge 

 running across the mouth of the sea from Cape Adare to King Edward VII Land. The 

 soundings on the ridge are less than 500 m., but the chart shows that there is probably a 

 slightly deeper channel through the ridge near the coast of Queen Victoria Land. Our 

 observations suggest that there is no deep channel, because although the data from the 

 southern part of the sea (Sts. RS 13-29) show that the bottom water has a temperature 

 between -0-30 and -1-97° C, the data available so far from the region outside the sea 

 indicate that none of this water escapes into the open ocean. Although the conditions 

 in winter in the Ross Sea may closely resemble those found by Brennecke (1 921) in the 

 neighbourhood of Vahsel Bay in the southern part of the Weddell Sea, and a large volume 

 of water may be formed with similar properties to that which sinks from the continental 

 shelf south-west of the Weddell Sea, the water apparently cannot reach the ocean outside, 

 and as far as can be seen at present the Ross Sea produces no cold bottom current. 



In section 15 (Plates XXXIV-XXXVI), between 160 and 130 W, the bottom water 

 is still warmer and more saline than it is north of the Ross Sea, but it advances farther 

 towards the north. The relatively high temperature and salinity show that the advance 

 is not caused by the current being reinforced by more water sinking from the con- 

 tinental shelf, and there is no doubt that it is due to the influence of the Cape Adare- 

 Easter Island ridge. Section 14 only crosses the ridge in 62-65 S, but section 15 follows 

 the ridge as far as 55 S, and a comparison of the two shows that the eastward bottom 

 current bends towards the north in the shallow water. The observations used in the 

 construction of Plate XLIV show that on the other side of the ridge, between 150 and 



