79. What are turbidity currents? 



Turbidity currents occur when sediments on the continental slope 

 are dislodged by earthquakes and begin sliding down the slope. A cur- 

 rent is created by the increased density of the sedinnent-laden water. 

 This current, in turn, dislodges more sediment which continues down- 

 slope at greater speed. 



Turbidity currents have broken off series of submarine cables; the 

 time between the cable breaks enables one to compute their approxi- 

 mate speed. If the slope is steep and long, the speed may reach 50 

 miles per hour. 



The sediment- laden currents cause scouring of the sea floor; it is 

 believed that they contribute to the flushing and erosion of submarine 

 canyons. 



If the turbulence is sufficient to keep sediments in suspension, 

 turbidity currents may flow for great distances; the sediments are finally 

 deposited on the abyssal plains. 



Cowan, Robert C. 



Frontiers of the Sea, Doubleday and Company, 1962. 

 Deacon, G. E. R. 



Seas, Maps, and Men, Doubleday and Company, 1962. 

 Gaskell. T. F. 



World Beneath the Oceans, American Museum of Natural History, 



1964. 



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