THE earth's contour AND SURFACE SUBDIVISIONS. 19 



Great Britain stands on a broad continental border not over 600 feet 

 deep, and is therefore part of the European continent. A large part of the 

 German Ocean is not over 95 feet deep. 



In a similar manner, the East India Islands down to a line by the north 

 of New Guinea and Celebes are a part of Asia, the depth of the seas between 

 seldom exceeding 300 feet, while New Guinea is a part of Australia. In like 

 manner, the Falkland Islands are a part of South America. 



These facts with respect to the 100-fathom (600 feet) limit off the 

 American and other coasts are illustrated on the following map. 



(6) Depths of the ocean. — The depths of the ocean are given on the 

 following bathymetric map, prepared by the author from the charts of 

 the United States and British Hydrographic Department, and from the 

 soundings of the vessels of the United States Eish Commission. The lines 

 marking equal depths are made heaviest for the greatest depths, as explained 

 on the map. The depths are given in 100 fathoms, 21 meaning 2100 

 fathoms (12,600 feet). 



The mean depth of the whole ocean has been estimated at 14,000 feet ; 

 that of the North Atlantic, at 15,000 ; and that of the North Pacific, at 16,000 

 feet. As exhibited on the map, the western half of the Pacific and Atlantic 

 oceans has greater mean depth than the eastern ; for it contains all the 

 4000-fathom areas, and the larger part of the oOOO-fathom areas. In the 

 Indian Ocean the eastern side is the deeper. 



In the North Atlantic, deep waters and abrupt slopes extend along near 

 the north shores of the West India Islands ; and in this line, north of Puerto 

 Eico, occurs the greatest depth of the Atlantic Ocean, 4561 fathoms, or 

 27,366 feet. The mean slope from the Puerto Eico coast to the bottom is 

 about 1 : 14. A deep trough with abrupt sides extends from this depression 

 westward, north of Haiti or San Domingo ; and south of Cuba there are 

 depths between 18,000 and 21,000 feet. 



In the Pacific, off the east shore of northern Japan and the Kurile 

 Islands, there is a long 4000-fathom area, in which the greatest depth found 

 is 4656 fathoms, or 27,936 feet. An isolated depression of 4475 exists south 

 of the largest end of the Ladrone Islands, and others over 4000 fathoms 

 southeast of the Eriendly Islands. 



In the North Atlantic, between Greenland and Iceland and Norway, the 

 great Scandinavian plateau lies at a depth, in general, of only 1500 to 3000 

 feet; and along one course the greatest depth does not exceed 3600 feet. 

 Iceland stands upon it and is prolonged in a ridge under water southwest- 

 ward for 750 miles, and northeastward to the island of Jan Mayen. The 

 plateau has to the north of it a large, deep region of 12,000 to 15,000 feet. 

 To the southward it is prolonged southwestward in a relatively shallow area, 

 called the Dolphin shoal, which passes near the middle of the ocean to the 

 parallel of 25° N. or beyond, with less than 12,000 feet of water over it, and 

 mostly under 9600 feet. Either side, the depths are 15,000 feet or over, and 



