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U.S. NATIONAL MUSEUM BULLETIN 291 



oxygen minimum layer. Again, the captures and specimens plotted on 

 this section are situated in the Antarctic Circumpolar Water Mass. 



160<* West Longitude; 48° to 65° South Latitudes 



The sections along the 160° west meridian transect the Pacific 

 Anarctic Ridge in the south and extend into the southern region of 

 the South Pacific Basin. Between 61°30' and 63°30'S the Pacific Ant- 

 arctic Eidge rises above 3000 m and at 62°19'S it crests at 2317 m. 



The temperature section shows the location of the Antarctic Con- 

 vergence close to 57°S (fig. 35). The 2.5° C isotherm descends nearly 

 vertically from the surface in the convergence zone to about 1000 m 

 where it levels off briefly; then it slopes evenly to 1750 m at 50°S. 

 Above the 2.5° isotherm the warmer ITpper Subantarctic Water ex- 

 tends to the Antarctic Convergence. The 2° isotherm drops vertically 

 from the convergence to 300 m before turning sharply southward ; it 

 envelops a great tongue of water between 2°-2.5°. At 58°S the layer 

 enclosed by the 2° isotherm is over 1200 m thick. The 2° isotherm 

 makes it southernmost penetration to just beyond 62°30'S between 450 

 and 700 m. Then it slopes into deeper water as it passes northward, and 

 it lies at 2500 m at 50°S. Only a narrow band of water exists between 

 the 1.5° and 2° isotherms. 



Figure 35. — Vertical section, 160°W, 48°-65°S; temperature °C, oxygen concentration 

 ml/L. Capture points of Bathyteuthis abyssicola. 



