148 THE OCEAN FLOOR 



This notion of coastal and subcoastal erosion by 

 turbidity currents was later expanded to include the 

 erosion of sediments at great depths and a reshuffling 

 of sediments which upsets the natural sequence of 

 strata/^ 



Once the ruggedness of the bottom profile in great 

 depths stands revealed, as through the "Albatross" 

 echograms, one condition of turbidity currents, namely 

 steep slopes charged with sediments, is accounted for. 

 The releasing factor, where surface waves are lacking, 

 can be found in submarine landslides set in movement 

 by volcanic eruptions in great depths or by seaquakes. 

 Some adherents of Kuenen's hypothesis have even gone 

 so far as to ascribe to turbidity currents a dominating 

 influence on deep-sea sediments, claiming that their 

 frequent occurrence reshuffles the sediments and makes 

 the taking of long cores useless. Let us see if recent 

 contributions to the knowledge of these important 

 currents justify the emphasis placed upon them. 



In Chapter 5 it was pointed out that turbidity cur- 

 rents have been invoked as a means of transportation 

 for bottom sediments to explain, especially, so-called 

 graded bedding, deep-sea sand, and the transfer of 

 shallow-water benthonic organisms into much greater 

 depths. Cases of graded bedding have repeatedly been 

 observed in long sediment cores raised from the 

 "Albatross," both in the Mediterranean and in the 

 equatorial Atlantic Ocean. It seems very probable that 

 masses of sediment may be set in motion along slopes 



