INVESTIGATIONS OF STRATIGRAPHY 105 



Arrhenius states that his studies of the East Pacific 

 sediments have not yielded any quantitative results 

 concerning the influence of the weight of the overlying 

 strata on the water content of an underlying stratum. 

 He assumes that the effect is so small — insofar as the 

 uppermost ten meters are concerned — that it is usually 

 masked by other variations in the composition of the 

 sediment. In calcareous f acies of the east eupelagic area 

 even the longest core (15 meters) does not give any 

 unquestionable evidence of expulsion of water by com- 

 paction. 



It is of interest to compare Arrhenius' interpretation 

 of changes in calcareous sedimentation — that they are 

 due to a strong upwelling in equatorial divergences 

 with a consequently improved nutrition of the surface 

 plankton — with the earlier interpretation by Schott, 

 who assumes that during glacial epochs surface water in 

 the tropics was cooled by as much as 10° centigrade, 

 so that the extraction of calcium carbonate was much 

 reduced. If this were true, the glacial stares ou^ht to 

 be characterized by a low lime content in the sediments, 

 whereas according to Arrhenius the reverse is the case. 



As Revelle has recently pointed out, there is not 

 necessarily any contradiction between the two views. ^ 

 In some regions the cooling of the surface water may 

 have had a predominant effect on tropical pelagic 

 sediments during the glacial periods, whereas in others 

 the increased productivity brought about by intensified 

 atmospheric and oceanic circulation may have been 



