23. What does the sea floor look like? 



The sea bottom is divided into three distinct areas: the continental 

 shelf, the continental slope, and the ocean floor. 



The continental shelf has numerous hills, ridges, terraces, and even 

 canyons comparable to the Grand Canyon. The average width of the 

 shelf is about 30 miles, but it may extend several hundred miles from 

 shore. The continental slope, between the shelf and the deep ocean, has 

 an average slope of 2 to 3 degrees, although the slope off a volcanic 

 island may be as much as 50 degrees. 



Features of the ocean bottom are comparable to those on land. Many 

 mountains under the sea are higher than Mt. Everest. All oceans except 

 the North Pacific are divided by an almost continuous system of moun- 

 tains, the largest being the Mid- Atlantic Ridge. 



Most of the deep-ocean floor is made up of basins surrounded by 

 walls of lesser depth. Oceanographers have compared the floor of the 

 Pacific to the surface of the moon. 



Deep trenches rim the Pacific in areas associated with great volcanic 

 activity and lie near islands and continental slopes. The deepest known 

 trenches are in the Western Pacific. 



Scientists once believed that the ocean floor was covered by a layer 

 of recently deposited sediments, but it is now known that sediments 

 deposited 100 million years ago lie near the surface of the ocean floor 

 and in some areas are even exposed. 



Engel, Leonard and Editors of LIFE 



The Sea, Life Nature Library, Time Inc., 1961. 

 King, Cuchlaine A. M. 



Oceanography for Geographers, Edward Arnold Ltd. (London), 



1962. 

 Yasso, Warren E. 



Oceanography, A Study of Inner Space, Holt, Rinehart and Winston, 



1965. 



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