CHARACTER OF THE BOTTOil OF THE EASTERN TROPICAL PACIFIC. 5 



extension reaches, no soundings indicate as yet. It is interesting to note 

 that along the Mexican coast tliere are a number of deep disconnected basins 

 lying close to the shore, just as there are a number of discorniected deeps 

 close along the South American coast, extending from oH Callao to off 

 Caldera, Chili, opposite high volcanoes or elevated chains of mountains. 

 These basins and a great part of the steep Mexican continental shelf form a 

 deep channel, separating in places the oceanic slope from the steep conti- 

 nental slope. The steepness of the continental shelf is especially well seen 

 off Acapulco and Manzanilla. One of the small basins along the Mexican 

 coast, with 2661 fathoms, lies off Sebastian Viscaino Bay; a second south of 

 Tres Marias with 2395 fathoms ; another with more than 2900 fathoms is 

 to the west of Manzanilla Bay ; a third to the southeast of Acapulco has 

 about the same depth, and a fourth with 2500 fathoms is off San Jose, 

 Guatemala. Our last soundings off Acapulco, about 29 miles south of the 

 lighthouse, in 2494 fathoms, showed the western extension of one of these 

 deep holes lying to the east of Acapulco. These small basins off the west 

 coast, close to the shore, at the foot of a steep continental slope, are in 

 great contrast to the wide continental shelves of Yucatan and Florida, 

 which characterize the east coast of Central America and the east coast 

 of the United States from Florida to the Banks of Newfoundland. 



CHARACTER OF THE BOTTOM OF THE EASTERN TROPICAL PACIFIC. 



Plate 3. 



The bottom of the area explored by the "Albatross" in 1891 is covered 

 by green and brown mud mixed with masses of decayed and decaying vege- 

 table matter. South of this area we come upon the great tracts of tlie 

 Eastern Pacific the bottom of which is covered by manganese nodules. The 

 extent of this tract is shown in Plate 3, where are given the northern and 

 eastern limits of the manganese nodules as well as its southern limit extend- 

 ing from Easter Island to Manga Reva. From the northern extremity of 

 Moser Basin the line forming the northern limit of the manganese nodules 

 runs in a southeasterly direction to about 100' W. Long., and 5" south of 

 the equator where it runs nearly due east off Aguja Point, its eastern line 

 then runs south, parallel to the South American coast. The southern limit 

 of the nodules as here given (PI. 3) is probably not its southernmost limit, 

 as the " Challenger " obtained manganese nodules a long way south in the 



