87. How thick is the sediment at the bottom of the ocean? 



Seismic refraction and reflection methods have enabled geophysicists 

 to make reliable estimates of the average thickness of unconsolidated 

 sediments on the ocean floor. 



Sediments in the Atlantic are about 750 meters thick. The rate of 

 deposition in the Pacific appears to be much slower (see question 4); 

 the thickness of red clay sediment in deep basins of the Pacific has been 

 found to be 100 to 200 meters. The average thickness of sediments in 

 the Pacific is about 300 meters. Basins of the Indian Ocean have about 

 the same sediment thickness as those of the Pacific. 



Calcareous deposits in equatorial regions average 400 meters in 

 thickness. 



Most sediments (sand, mud, and clay) come from the land; therefore, 

 the thickest deposits of sediments are near land. Thickness as great as 

 4,000 meters has been measured close to large land masses. 



Cowan, Robert C. 



Frontiers of the Sea, Doubleday and Company, 1960. 

 Ericson, David B., and Goesta Wollin 



The Deep artd the Past, Alfred A. Knopf, 1964. 

 Gaskell,T. F. 



World Beneath the Oceans, American Museum of Natural History, 



1964. 



105 



