150 THE DEPTH AND MARINE DEPOSITS OF THE PACIFIC OCEAN. 



Sir John Murray for the anniversary celebration of the Royal Geographical 

 Society of Australia, to which the reader is referred. 



The entire Pacific Ocean, excluding the fringe of partially enclosed seas 

 on its northern and western borders, that is to say, as bounded by the Aleu- 

 tian Islands on the north, by the Antarctic continent on the south, by the 

 Americas on the east, and by Kamschatka, the Kurile Islands, New Guinea, 

 Australia, and Tasmania on the west, is estimated to cover an area exceeding 

 sixty-two millions of square miles. Planimeter measurements give the fol- 

 lowing approximate areas between the consecutive contour lines of depth 

 drawn in at intervals of lOOOfathoms, and the percentages to the total area : — 



Less than 1000 fathoms ... 



1000 to 2000 « ... 



2000 to 3000 " ... 



3000 to 4000 " ... 



More than 4000 " ... 



From this table it seems that by far the largest area (about two-thirds of 

 the entire ocean) is that between 2000 and 3000 fathoms in depth. An in- 

 spection of the map shows this very well, for it is seen that the dominant 

 shade is the fifth one, indicating depths of 2000 to 3000 fathoms, which is 

 broken only by several irregular deeper and shallower areas. 



Depths of less than 1000 fathoms (1829 metres) are found round the shores 

 of the continents and islands and also in a few cases in the more central parts 

 of the ocean where submarine elevations have been discovered. 



Depths between 1000 and 2000 fathoms (1829-3658 metres) also occur 

 round the coasts, but in some localities cover a much larger area than the shal- 

 lower zone, as, for instance, off the coast of Central America, where there is a 

 large area, which has been called the Giilapagos Plateau ; and, again, off the 

 coast of South America, between 32° and 50° S., where there is a smaller area, 

 which has been called the Juan Fernandez Plateau. In the South Pacific 

 there is a broad tract extending from 38° to 74° S. and from 145° E. to 

 105° W., sending a branch northward into the Coral Sea; to the north 

 of this is a large area, stretching from 8° to 28° S., and from 102° to 142° W., 

 which has been called the Albatross Plateau. In the North Pacific there is 

 a small area oflFthe coast of Mexico, founded on two soundings taken during 

 the " Albatross " 1904-1905 cruise, and a second small area between 175° 

 and 179° E. and 21° and 23° N., as well as a few other small scattered areas. 



