GEOLOGICAL RECORD OX THE OCEAX FLOOR 147 



Fredrlksson (1958) and Fredriksson (1958). Still nobody has been 

 able to establish the rate of accretion on the earth's surface of fine 

 cosmic dust that might be of great geophysical significance. 

 Silicate chondrules like those in meteorites have, however, been 

 observed by Murray and Renard, and recently by Bramlette. 

 An interesting possibility for estimating the amount of cosmic 

 dust settling on the earth may be offered by the fact that the 

 meteorites, in contrast to terrestrial rocks, are reported to contain 

 considerable amounts of monoclinic magnesium-iron pyroxenes, 

 clinoenstatite and clinohypersthene, which are relatively easy to 

 concentrate, and which belong to a series of minerals which do not 

 readily decompose on the ocean floor. 



In a survey like this it has been necessary to limit the subject 

 to an impressionistic account of a few topics. It is impossible to 

 give justice, under such conditions, to all the interesting work that 

 has been done in the field, and to point out all the fascinating 

 possibilities that are now apparent. I hope, however, that I have 

 been able to convey a general impression of the wealth of infor- 

 mation that the pelagic sediments offer to those who devote 

 themselves to quantitative study of the past history of the solid 

 earth, its ocean and atmosphere, and its interrelation with outer 

 space. 



REFERENCES 



Arrhenius, G. 1952. Sediment cores from the East Pacific. Rept. Swed. 

 Deep Sea Expedition 5, Goteborg, Sweden. 



. 1959a. Sedimentation on the ocean floor. Researches in 



Geochemistry, Ph. H. Abelson, Editor. John Wiley and Sons, New 

 York, N.Y. 



. 1959b. Climatic records on the ocean floor. Rossby Memo- 

 rial Volume, B. Bolin, Editor. Rockefeller Institute Press, New 

 York, N.Y. 



Bramlette, M., and W. Bradley. 1942. Geology and biology of North 

 Atlantic deep sea cores between Newfoundland and Ireland. Lith- 

 ology and geologic interpretations. U.S. Geol. Survey Prof. Papers 

 No. 196. 



Castaing, R., and K. Fredriksson. 1958. Analyses of cosmic spherules 

 with an x-ray microanalyzer. Geochim. et Cosmochim. Acta, 14, 114. 



