882 



BIEDEL 



[CHAP. 33 



E M M'i' X 



F, '' F M ■" « «m 

 e e\E''x^ " "^.Jm 



20° 



Fig. 11. Tertiary and Quaternary micro fossils in surface sediments of the Pacific floor. 

 X marks sample positions, and if not accompanied by another letter the microfossil 

 assemblage is believed to be purely Quaternary. E, M and L indicate admixture of 

 early, middle and late Tertiary microfossils respectively: capitals if Tertiary forms are 

 estimated to constitute more than 20% of the microfossil assemblage, lower case if the 

 Tertiary admixture is estimated to constitute less than 20% of the assemblage. 

 Non-fossiliferous samples and those of doubtful age are not plotted; some available 

 data are omitted in areas of high sampling density. Some of the age assignments on 

 this and the next figure were made by M. X. Bramlette on the basis of coccolitho- 

 phorids. For a number of samples from the N.W. and S.W. Pacific, we are indebted to 

 the U.S.S.R. Academy of Sciences' Institute of Oceanography, the Japanese Hydro- 

 graphic Department and the British Museum (Natural History) {Challenger samples]. 



movements which keep the outcrop swept free of Quaternary deposits. 

 Reworked microfossils occurring at many localities in the deep Pacific indicate 

 that this type of disturbance is rather widespread (Fig. 11). 



7. Pre -Quaternary Paleoceanography 



Sediment cores collected from the deep-sea floor occasionally sample Tertiary 

 strata. The cores at present obtainable are usually not long enough to penetrate 

 a continuous sequence of fossiliferous sediments from the Recent through the 

 Pleistocene and Pliocene to the Miocene or Oligocene: most of the Tertiary 



