920 EMILIANI AND FLINT [CHAP. 34 



Radiocarbon dating and the discovery and development of some other 

 methods for absohite dating of Pleistocene materials, invention of the piston 

 core-sampler and the consequent intensive study of relatively long sections of 

 deep-sea sediments, refinements in the techniques for the study of continental 

 deposits (expecially loess and soil profiles), and the pollen-analytical work done 

 on some particularly long sections of lacustrine deposits have greatly advanced 

 Pleistocene science in the decade 1950-1960. Yet, many major advances remain 

 to be made before a clear picture of the Pleistocene Epoch as a whole will emerge. 

 On the one hand, the glacial and periglacial deposits on the continents show four 

 or five, and perhaps more, major glacial advances, each one of which appears 

 to have been double or multiple. On the other hand, the deep-sea cores f»rovide 

 us with a picture of repeated temperature cycles totalling perhaps ten or fifteen 

 during the past half- million years. Correlation between temperature cycles of 

 the deep-sea cores and glacial advances and retreats on the northern continents 

 seems established, at least tentatively, only for the past 100,000 years, i.e. back 

 into the last interglacial. Further, important advances in our knowledge of the 

 Pleistocene Epoch will probably require the collection and study of deep-sea 

 cores representing continuous stratigraphic sections much longer than the ones 

 presently available, together with absolute dating of both deep-sea and con- 

 tinental materials formed in the long Pleistocene time preceding the last inter- 

 glacial and significantly related to the climatic changes. In addition, much work 

 needs to be done on the Pleistocene of the Southern Hemisphere, both on land 

 and beneath the sea, as well as on continental deposits in equatorial and tropical 

 regions. Techniques for these studies have been already developed or are being 

 developed rapidly, so that a clear, world-wide picture of the history of the 

 Pleistocene may be achieved in the not-too-distant future. The picture, as 

 discussed in the introduction, will be of paramount importance in assessing 

 the rates at which many geojjhysical, geochemical, geological and biological 

 processes operate. 



References 



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Arrhenius, G., 1952. Sediment cores from the east Pacific. Reps. Swed. Deep-Sea Exped., 

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Bandy, O. L., 1956. Ecology of Foraminifera in northeastern Gulf of Mexico. U.S. Geol. 

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Bandy, O. L. and R. E. Arnal, 1957. Distribution of Recent Foraminifera off west coast 

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