136 DEPTHS OF THE OCEAN 



The principal area exceeding 2000 fathoms in depth is 

 continuous throughout the Atlantic, although much broken up 

 by areas of shallower water ; there are besides in places isolated 

 areas in which the depth exceeds 2000 fathoms, as in the Gulf 

 of Guinea, near the Canary Islands, at the northern extremity 

 of the Mid-Atlantic ridge (as already mentioned), as well as in 

 the Norwegian Sea, the Mediterranean Sea, the Carribbean 

 Sea, and the Gulf of Mexico. 



The areas exceeding 3000 fathoms in depth (" deeps ") will 

 be referred to under a later heading. 



Pacific Ocean. — The Pacific may be looked upon as extend- 

 ing southwards from the Arctic circle in Behring Strait to the 

 Antarctic continent, including the fringe of partially enclosed 

 seas along its western border, and as being separated from 

 the Atlantic in the south at the meridian of Cape Horn (long. 

 70' W.), and from the Indian Ocean at the meridian of Tasmania 

 (long. 147° E.). As thus defined the Pacific Ocean covers an 

 area of about 68,634,000 square English miles, the distribution 

 of depth being shown in the following table : — 



These figures show that nearly nine- tenths of the Pacific 

 sea- floor are covered by water exceeding 1000 fathoms in depth, 

 and nearly three- fourths by water exceeding 2000 fathoms in 

 Continental depth. Unlike the Atlantic, the shallowest zone in the Pacific 

 hrihe^PactfiT (o- 1 000 fathoms) is smaller than the succeeding zone (1000-2000 

 fathoms), indicating that the Pacific land -slopes are on the 

 average steeper than those of the Atlantic, and this is strikingly 

 shown by the near approach to the land of the deep contours 

 in certain regions, as off the coasts of South America, North 

 America, Japan, the Philippine Islands, and South-East Australia. 

 The ratio between the two areas on either side of the 500-fathoms 

 line is not so strikino- as in the case of the Atlantic, the area 



