362 THE DEEP SEA 



minerals, philllpsite, is also especially common in the South 

 Pacific, and forms up to nearly 50% of some pelagic clay. Figure 

 9a shows the abundant phillipsite crystals unseparated from other 

 fine sediment. The associations, especially where the phillipsite is 

 in concentric bands with palagonite around incompletely altered 

 basaltic glass, support the conclusion of Murray and Renard 

 (1891, pp. 405-411) that the phillipsite was derived from the 

 alteration of pyroclastics. Arrhenius is investigating interesting 

 features of phillipsite which include high concentration of certain 

 elements, such as the radioactive ones that show alpha emissions 

 like that illustrated from the fish debris (Fig. 8a). Derivation of 

 such elements from the bottom water, however, does not preclude 

 derivation of the essential constituents of phillipsite from alteration 

 of the pyroclastics by the bottom water. Such derivation of the 

 silica, alumina, calcium, and perhaps the potassium, rather than 

 directly from the ocean water, seems probable, as the common 

 association of zeolites with altered pyroclastics, even in nonmarine 

 waters, is well known. 



The pelagic clay of the North Pacific shows differences from 

 that of the South Pacific that may be related in part to closer 

 proximity to land sources, and other factors to be mentioned, 

 which have increased the rate of accumulation. Goldberg's 

 determinations here show rates between 1 and 2 mm per thousand 

 years here compared with rates of 14 mm in the South Pacific. The 

 iron and especially manganese content is distinctly less than in the 

 South Pacific. Pyroclastics and their alteration products are also 

 less important here, probably in part because more diluted with 

 other material. The sparsely disseminated volcanic shards of 

 alkalic glass are unaltered in the near surface sediment, and 

 indicate much less susceptibility to alteration than a basaltic glass. 



The quartz content, as particles averaging less than 10 microns, 

 is relatively high, especially near 30° N Lat in the Pacific, and 

 Rex and Goldberg (1958) relate these high percentages to dust 

 fallout, mostly from the jet stream circling the globe near this 

 latitude. Menard (1955, p. 240) indicated that turbidity current 

 deposition is important in the northwest Pacific, and perhaps the 

 finest of the suspended particles from this may also contribute 



