Cores taken in the Amvindsen Sea anti the BeHingaliausen Sea at depths 

 of 1,8U0 and 1,9^0 meters, showed marked contrasts in their sediments. 

 The core taken off Peter I Island in the Bellingshausen. Sea was at the 

 edge of the continental shelf, which sweeps out from the coast to in- 

 clude the island. The core taken off Mt. Siple in Amundsen Sea was on 

 the slopes of an vmcharted seamount, which rose from a depth of 6, $00 

 meters. No penetration was obtained in tlie Mt, Siple core, and only 

 11 inches of core was obtained at Peter I Island, At Mt. Siple, the 

 corer hit bottom with a bounce, and only a small sample of coarsn sand 

 and gravel with some silt was retained within the core catcher. The 

 sphericity of these particles vias moderately high to high, th/? loiand- 

 ness ranged from subrounded to very angular, and the surface texture 

 was rough dull, smooth, or pitted, (Uobigerina was the predominant 

 sediment type found and volcanic sand the secondary type. Feldspar 

 also was noted. The only organic remains consisted of some calcareous 

 foraminifera. The core taken off Peter I Island was very similar from 

 top to bottom. The sediment color was grayish brown, sphericity varied 

 from low to high, roundness of the particles ranged from subangular 

 to very angular at the top and rounded to very angular at the bottom 

 of the core. Surface texture was rough polished on mineral grains 

 and some volcanic glass fragments, but was dull smooth on other parti- 

 cles. An average of 18 percent of the particles in the core were of 

 sand size or larger, coarse silt made up 60 percent of the sample at 

 the top of the core and k9 percent of the sample at the bottom of the 

 core. Clay sized particles made up ohly 11 and 17 percent of the 

 samples at the top and bottom of the core. The sorting coefficient was 

 1,67 at the top and 2,00 at the bottom of the core; skewness in li units 

 was -0,10 and 0,00, and the median diameter of particles in ^ units was 

 5,37 and 5,28, respectively. Volcanic glass was the dominant mineral, 

 quartz was secondary and feldspar was also present. Organic remains 

 consisted of arenaceous and calcareous foraminifera, sponge spicules, 

 diatoms, and radiolaria, A heavy liquid separation showed tte 

 following percentages at the bottom of the core; light weight sand 

 fraction 60, heavy sand fraction liO, magnetic light sand fraction 

 0,9, and magnetic heavy sand fraction 7» The quantity of heavy 

 magnetic particles was unusually high. In other regions, where com- 

 parisons have been made, such high quantities are usually associated 

 with local magnetic anomalies. Organic carbon in the Peter I Island 

 core averaged 0,3U percent, 



li, Bransfield Strait 



Bransfield Strait lies on the continental shelf which extends from 

 7$ to over 100 miles north of the South Shetland Islands, which form 

 the northern shores of the strait, Thrco cores were taken, one at each 

 of the oceanographic stations occupied; namely, west of Deception Island, 

 in the middle of the strait, and north of D'Urville Island, The sedi- 

 ments showed a decided increase of particle size toward the east. 



51 



