842 ERicsoN [chap. 31 



of deep circulation was in general from southwest to northeast. With circulation 

 in the reverse sense station A 164-44 would probably have been exposed to 

 current scour judging from its position with respect to the seamount. 



It is significant that the uppermost post-glacial layers in both cores contain 

 fairly large percentages of coarse fraction. While this may be partly due to 

 greater productivity of large species of planktonic Foraminifera such as Globoro- 

 talia menardii under present climatic conditions, the 52% of coarse fraction in 

 the top layer of core A173-4 appears to be too great to be accounted for in this 

 way. More probably station A 173-4 is presently subject to weak current scour. 

 This suggests that the direction and velocity of deep circulation in the vicinity 

 of the Muir seamount is now just about the same as it was during the period of 

 warm climate represented by the jlexuosa zone. 



With these few data no closer definition of cm-rent directions is possible. The 

 important thing is that we have in these two cores compelling evidence of signi- 

 ficant changes in deep circulation which are correlatable with climatic changes 

 of the late Pleistocene. Presumably application of this method of analysis to a 

 series of cores suitably spaced around a seamount could yield interesting 

 evidence regarding variations in deep circulation in the Atlantic during the 

 Pleistocene epoch. 



References 



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 Ericson, D. B., 1959. Coiling direction of Oloborotalia pachyderma as a climatic index. 



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 Ericson, D. B., W. S. Broecker, J. L. Kulp and G. Wollin, 1956. Late Pleistocene climates 



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