150 



OBSERVATIONS AND RESULTS IN PHYSICAL OCEANOGRAPHY 



north latitude and 34° west longitude, by soundings 122, 

 123, 124, and 125. The adjacent 3000-meter line west of 

 this is embayed toward the east to soundings 113 and 

 114, and passes between soundings 129 and 130. As the 

 Carnegie soundings between southern Greenland and the 

 Grand Banks were considered in the preparation of the 

 bathymetric chart in "The Marion expedition to Davis 

 Strait and Baffin Bay," Scientific Results, part 1, refer- 

 ence is made to that chart for this area. 



Again referring to the Monaco chart, two soundings 

 (nos. 21 and 23) of between 3000 and 4000 meters are lo- 

 cated within the 4000-meter contour of the East Atlantic 

 Depression. Whether these are isolated peaks or con- 

 nect with the 3000- to 4000-meter bottom to the west and 

 northwest is open to question. The northern part of the 

 Azores Plateau apparently is more extensive than indi- 

 cated on the chart, the 3000-meter contour on the east- 

 ern side extending to the northeastward to include sound- 

 ings 19 and 20, and on the western side extending to the 

 westward to include soundings 13 to 17 inclusive. Sound- 

 ing 18 represents a new peak of the group near Chaucer 

 Bank. Soundings 11 and 12, together with the now al- 

 tered shape of the 3000-meter contour, make it seem 

 probable that the 3000- to 4000-meter area between 

 latitudes 42° and 44° north and between longitudes 37° 

 and 38° west is connected with the continuous 3000- to 

 4000-meter belt along the western side of the Middle 

 Atlantic Rise. 



East of the southern tip of the Grand Banks the 

 4000-meter contour needs to be pushed somewhat to the 

 eastward to include soundings 163, 164, and 165, and 

 somewhat south of this, in about latitude 41° 30' north, 

 needs an indentation to exclude sounding 169. Still 

 farther south between about latitudes 37° 30' and 38° 30' 

 north, the 5000-meter line should be extended westward 

 to conform to soundings 175, 7, 176, and 177. Then it 

 is embayed eastward in the vicinity of the 37th parallel 

 in consideration of soundings 178 to 183 inclusive. 

 Soundings 184 to 189 inclusive indicate that this 4000- 

 to 5000-meter arm is connected by means of a low ridge 

 to the general 4000- to 5000-meter belt along the west- 

 ern side of the Middle Atlantic Rise. This leaves an 

 isolated depression of more than 5000 meters depth run- 

 ning northeastward from the ridge just mentioned. As 

 one approaches the Dolphin Plateau from the northwest, 

 the 4000-meter line should be moved somewhat west- 

 ward to pass between soundings 190 and 191; the 3000- 

 meter contour either cuts the plateau into two sections 

 or is deeply embayed on each side to conform to sound- 

 ings 197 and 198. 



On the eastern slope of the Middle Atlantic Rise in 

 this vicinity, the 4000-meter line is extended sharply 

 southward by soundings 201 to 204 inclusive. Sounding 

 206 moves the 5000-meter contour eastward. Sounding 

 208 may either represent an isolated pool or a narrow 

 valley communicating with Moseley Deep. The embay- 

 ment demanded just south of here by soundings 211 and 

 213 lend favor to the valley idea. Farther south in 

 about latitudes 15° to 16° north, soundings 220, 221, and 

 225 may again require the considerable invasion of the 

 Moseley Deep by the 5000-meter contour or they may 

 be isolated elevations. Still farther south in about lati- 

 tudes 10° to 12° north, this same 5000-meter line takes 

 on a very complicated pattern with a general displace- 

 ment to the southwestward by soundings 231 to 234 in- 

 clusive and 243 to 249 inclusive. Because of lack of 

 data it is difficult to state on which side of the Middle 



Atlantic Rise sounding 238 is located, but in either case 

 one of the 4000-meter lines must be altered to accomo- 

 date it. 



Between about latitudes 11° and 12° north the 4000- 

 meter line on the eastern side of the Middle Atlantic 

 Rise takes on an S-pattern to conform to soundings 253 

 to 257 inclusive. Crossing the rise at this latitude a 

 3000-meter contour is required to encircle soundings 

 261 and 262. The 4000-meter line is extended in a spur 

 to the westward; the isolated area deeper than 5000 me- 

 ters just to the south of this spur is greatly diminished. 



Near here, the southeastern corner of the 5000- 

 meter contour of the West Atlantic Depression is em- 

 bayed to the eastward so as to pass between soundings 

 270 and 271, the northern boundary of the embayment 

 following more or less the line of soundings 271 to 282 

 inclusive. Just east of Barbados the 3000-meter contour 

 line should be moved northward to include soundings 300 

 to 302 inclusive. 



In the Caribbean Sea south of Porto Rico, sounding 

 315 apparently indicates an isolated peak which must be 

 encircled by a 4000-meter contour. Farther to the west 

 between Haiti and western Venezuela and about midway 

 between them, soundings 318 and 319 indicate the pres- 

 ence of a rise which must be encircled by a 4000-meter 

 contour. 



In the southeastern Pacific one of the most impor- 

 tant revelations of the Carnegie soundings is that the 

 threshold level of the Easter Island Rise is of a depth 

 less than 3000 meters from about latitudes 9° to 39° 

 south. The 3000-meter contour on the western side of 

 the rise extends in a general northerly direction from 

 about latitude 39° south and longitude 113° west to about 

 latitude 15° south and longitude 115° west, and thence 

 northeastward to about latitude 9° south and longitude 

 108° west. From this point it curves southward, along 

 the eastern side of the rise, concave toward the east, 

 passing close to the northern side of Easter Island, then 

 extending to the east to include the rocks of Sala y Gomez, 

 then following an irregular course to about latitude 36° 

 south and longitude 104° 30' west, and then southwest- 

 ward to close the area. These surmises are based on 

 soundings 373 to 421 inclusive and 543 to 547 inclusive 

 combined with the chart values. 



Soundings 424 to 429 inclusive indicate that the em- 

 bayed 4000-meter line to the south of the Easter Island 

 Rise at about longitude 100° west does not come as far 

 north as has been supposed. Merriam Ridge, disclosed 

 by soundings 458 to 461 inclusive, seems probably to be 

 an extension to the northwest of the base on which rest 

 the islands of San Felix and San Ambrosio. Just north 

 of Merriam Ridge, soundings 463 and 464 require that 

 the 4000-meter contour be moved somewhat to the south; 

 soundings 468 to 471 seem to show that the isolated area 

 of between 3000 and 4000 meters depth is larger than 

 that shown on the chart as a narrow strip between about 

 latitude 17° south and longtiude 75° 30' west and about 

 latitude 15° south and longitude 77° west. 



Soundings 481 and 482 show that the 5000-meter con- 

 tour of the Milne-Edwards Trench extends farther to the 

 northwest. The 4000-meter line on the eastern side of 

 the Easter Island Rise apparently follows the course of 

 the Carnegie from about longitude 92° west to about 

 longitude 105° west, weaving in and out among soundings 

 505 to 534 inclusive, with Bauer Deep at sounding 519 as 

 a narrow deep bay. 



The caldron In the Easter Island Rise, shown on the 



