300 



REX AND GOLDBERG 



[chap. 5 



farthest from land in the area north of Hawaii, where around 25% of the solid 

 phases consist of quartz. 



The Stoke's law settling times of approximately two years for 10 micron 

 particles to depths of 4000 meters (average Pacific deep-sea depth), in conjunc- 

 tion with the above observation of the highest quartz contents being farthest 

 from land, have suggested modes of transport other than water currents. It is 

 very difficult to fit the observed latitudinal variations with any observed 

 circulation of Pacific waters. 



A number of lines of evidence have strengthened the hypothesis of the 

 atmospheric transportation of the quartz. These include the observed correla- 

 tion of quartz distribution in sediments to exposed arid land areas and the 

 location of the jet streams in both hemispheres. Also the high wind velocities 

 of the main jet streams in the upper troposphere make them logical transporting 



25 

 ^i 15 



if lOh 

 5 





SOUTH LATITUDE NORTH 



Fig. 2. The quartz concentrations and arid land areas as a function of latitude. 



agents. Near-surface filter-feeding plankton, collected from a number of mid- 

 Pacific areas, all contained mineral debris, including quartz, mica and feldspars 

 in their guts, indicating recent dust falls. Finally, X-ray diffraction analysis of 

 the Asahikawa fall-out and pelagic red clays (on a calcium carbonate free basis) 

 from north of Hawaii are indistinguishable in nearly all details. 



The mica and feldspars show a close correlation with quartz in sediment 

 from the Pacific and they also occur in the Asahikawa fall-out. In Fig. 3 feldspar 

 contents are seen to show linear dependences upon the quartz concentrations 

 with one correlation under the path of the westerlies of the Northern Hemi- 

 sphere and still another under the easterly tropical circulation. 



The micaceous clay mineral illite shows a distribution pattern in the Pacific 

 somewhat paralleling that of quartz (Griffin and Goldberg, Volume 3). 

 Illite is much more prevalent in the North than in the South Pacific and its 

 concentration follows a latitudinal band somewhat broader and more diffuse 



