DISCUSSION OF CARNEGIE SOUNDINGS 



151 



chart between about latitudes 3° and 9° south and about 

 longitudes 100° and 104° west, is modified by soundings 

 366 to 369 inclusive. 



Malpelo Island is shown on the chart as resting on a 

 platform of less than 3000 meter depth, which is con- 

 nected to the South American continent. Soundings 340, 

 and 343 to 346 inclusive, however, indicate that this 

 platform is separated from the continent by a channel 

 greater than 3000 meters in depth and having a small but 

 deep depression in its middle (sounding 344). 



On the western side of the Easter Island Rise sound- 

 ings 577 to 601 inclusive require that the 4000-meter 

 contour line extend in a long tongue as far west as long- 

 itude 131° west in about latitude 17° south. 



In the Tuamotu Archipelago soundings 620 to 662 in- 

 dicate that the 4000-meter line surrounding the northern 

 group includes the islands of Angatau, Fakaina, Rekare- 

 ka, Taueri, Tatakoto, Pukaruha, and Reao, were it not 

 for the single old sounding of 4000 meters at latitud 

 18° 08' south, longitude 141° 49' west. Soundings 668 

 and 669 show that the base of Anaa Island extends to the 

 southeastward. In the Society Islands soundings 687 and 

 688 of more than 3000 meters separate Morea from 

 Husheine; soundings 699 and 700 may mean that a chan- 

 nel deeper than 4000 meters separates Bellingshausen, 

 Scilly, and Mopelia from the rest of the group. West of 

 of Tahiti and south of Raiatea the 4000-meter line needs 

 to be moved south to conform to soundings 694 and 695. 



West of the Society Islands in about latitude 16° 

 south the 5000-meter contour is more deeply embayed 

 to the east, as is shown by soundings 712 to 723 inclu- 

 sive. Following westward along the north side of this 

 bay, this contour continues until about the position of 

 sounding 731 and thence northward nearly to Nassau Is- 

 land to pass between soundings 1482 and 1483. North- 

 eastward of Danger, Nassau, and Suwarrow islands lies 

 the large submarine platform on which stand the islands 

 of Manahiki and Ryerson. A 4000-meter contour line 

 apparently surrounds this entire area, and a sizable 

 area within this is enclosed in a 3000-meter line (sound- 

 ings 1458 to 1480 inclusive). Soundings 1452 to 1455 in- 

 clusive show a trench of more than 5000 meters between 

 Manahiki and Penrhyn islands. 



East of Starbuck Island soundings 1423 to 1426 show 

 the 5000 -meter line to be embayed somewhat to the north; 

 depths between Maiden Island and FilippoBank are great- 

 er than 4000 meters. At sounding 1415 the bottom is ele- 

 vated about 800 meters above the neighboring floor. 



Between about longitudes 149" and 160° west, the 

 chart shows a 5000-meter contour running in an east- 

 west direction just north of the equator. The chart also 

 shows a 5000-meter line surrounding Christmas, Fan- 

 ning, Washington, and Palmyra islands. The paucity of 

 soundings southeast of Fanning Island leaves much to 

 conjecture, yet in view of soundings 1389 to 1410 inclu- 

 sive it seems likely that this area is all of depth less 

 than 5000 meters and that the 5000-meter line runs from 

 a point just west of Jarvis Island northward to meet the 

 chart line at about latitude 2° north, longitude 160° west, 

 that it then follows the course on the chart around the 

 islands mentioned as far as about latitude 7° north, 

 longitude 156° 30' west, whence it follows the 7th paral- 

 el eastward to again join the chart line northward near 

 longitude 149° west. This must remain a conjecture 

 until more data are at hand. Soundings 1403 to 1408 in- 

 clusive indicate that a small closed 4000-meter contour 

 is required in this vicinity. 



A 5000-meter contour line apparently follows the 

 course of the Carnegie from soundings 1332 to 1396, 

 threading in and out among the soundings. This would 

 indicate two things, namely, that an extensive arm 

 thrusts southwestward from what is shown as a caldron 

 centered about 11" north latitude and 130° west longi- 

 tude, and that the supposed caldron is in communication 

 with and is not shut off from the 5000- to 6000-meter 

 depths of the North Pacific Basin. 



Between about longitudes 138° and 144° west an 

 east-west 5000-meter contour is shown between lati- 

 tudes 24' and 25° north. This needs to be moved farther 

 south to conform to soundings 1314 to 1319 inclusive and 

 1190 to 1193 inclusive. This same 5000-meter contour 

 farther north, in about latitude 30° 30' north and longi- 

 tude 140° west, must be extended northward in view of 

 soundings 1289 to 1292 inclusive. 



A sounding (no. 1282) of less than 5000 meters ap- 

 pears at longitude 145° west and a sounding of more 

 than 6000 meters (no. 1250) appears northwest of Mur- 

 ray Deep. The 5000-meter line north of the Hawaiian 

 Islands probably extends northwestward as far as about 

 latitude 28° 30' north and about longitude 161° west 

 (soundings 1229 to 1238 inclusive). From this baseAult 

 Peak (sounding 1231) rises to a depth of 2548 meters. 



The Hawaiian, Gilbert, and Marshall groups are all 

 shown as having a common base of less than 5000 meters 

 depth. The southern part of this 5000-meter contour line 

 is shown on the chart as being just south of the equator 

 and just north of the Phoenix group. Soundings 798 to 

 824 inclusive seem to indicate that the 5000-meter line 

 is deeply embayed northwestward with a deeper area 

 between the Gilbert and Marshall groups to the south- 

 west and the Hawaiian group to the northeast. The 

 southern part of the 5000-meter line around the Hawai- 

 ian group is apparently moved northward to about lati- 

 tude 3° north to pass between soundings 807 and 808, 

 thence northwestward and returning north between sound- 

 ings 815 and 816. The line probably continues to the 

 north to connect with what is shown on the chart as a 

 closed depression of more than 5000 meters in the 

 neighborhood of latitude 20° north, longitude 175° west. 

 From the western end of this supposed depression, the 

 5000-meter line probably continues southwestward, join- 

 ing the chart line at about latitude 19° north, longitude 

 178° east. Soundings 839 and 841 seem to show that a 

 low ridge connects this western end of the Hawaiian Rise 

 with the Marshall base near Taongui Island- -the north- 

 ermost of the Marshall group. A small area enclosed 

 by a 6000-meter contour is required by soundings 823 

 and 824; a 4000-meter line must surround sounding 814. 

 Soundings 830 to 833 indicate another small imcharted 

 rise. 



We find from soundings 849 to 859 inclusive that the 

 5000-meter line surrounding Wake Island extends much 

 farther to the southeast of the island than to the north- 

 west. 



Referring now to Japanese Hydrographic Department 

 ChartNo.6080, Carnegie soundings 865 to 873 inclusive 

 introduce new contour patterns around the submarine 

 mountains at about latitudes 20° to 22° north and longi- 

 tudes 162° to 162° east. Additional newly found peaks in 

 this submarine range between this locality and Nero 

 Deep are shown by soundings 883, 896, and 900. On the 

 western border of Nero Deep east of Rota Island, sound- 

 ings 906 and 907 require the 5000- and 6000-meter lines 

 to be moved more to the eastward. 



