696 



ARRHENIUS 



[chap. 25 



oligoclase in most Pacific sediments; commonly several species are present 

 together. Large grains of orthoclase, microcline and sanidine, indicating 

 occurrences of acid igneous rocks, are not uncommon within the predominantly 

 basaltic province of the Pacific basin (Revelle, 1944, pp. 10, 18-39). A detailed 



Equatorial Pacific 

 rate of circulation 



time 

 years 



Fig. 



24. Relative tx'ade-wind 

 intensity as a function 

 of geological time. The 

 relative intensity is esti- 

 mated from the ensuing 

 productivity changes at 

 the Equatorial Diverg- 

 ence. (From Arrhenius, 

 1952.) 



PELAGIC SEDIMENTS 



— AEOLIAN DUST 



0.5 1 2 3 4 6 8 10 20 40 



particle size yL, 



Fig. 25. Particle-size distribution in pelagic sediments 

 from the North Pacific and in eolian dust from 

 Illinois. (Data from Rex, 1958; Udden, 1914.) 



investigation by Peterson and Goldberg (1962) shows that such feldspar species 

 prevail over a large part of the East Pacific Rise. For the Atlantic, Radczewski 

 (1937) and Leinz (1937) showed that acidic rocks must have been the main 

 source of feldspar in the Cape Verde and the Guinea Basins, inasmuch as the 



