CHAP. 34] THE PLEISTOCENE RECORD 915 



important glaciations occurred before the first major glaciation. Cores 58 and 62 

 are believed to contain a complete section of Pleistocene sediments and to pene- 

 trate into the Pliocene (Arrhenius, 1952). The position of the Plio-Pleistocene 

 boundary in these cores is unknown because a correlation with the Plio- 

 Pleistocene sections of Italy has not yet been made. On paleotemperature 

 evidence alone, the boundary has been placed at 610 cm below the top in core 58 

 (Emiliani, 1955), but some other lower levels, such as those at 780 or 880 cm 

 below the top, could also be chosen. Ages of 600,000 to 900,000 years can be 

 estimated for these levels (cf. Emiliani, 1955). 



So far, only a few cores from the Indian and Pacific Oceans have been ana- 

 lyzed micropaleontologically. The ratio Glohigerina hulloides to Glohorofalia 

 menardii menardii, believed to be inversely proportional to temperature, was 

 found to vary markedly in six relatively short cores from the western Indian 

 Ocean (Stubbings, 1939), but the relationship of these variations to Pleistocene 

 ages is obscure. Equally obscure is the relationship between the relative abun- 

 dances of pelagic Foraminifera in a long core from the central Pacific and 

 Pleistocene events, although a correlation with the Atlantic cores has been 

 attempted (Brotzen and Dinesen, 1959). 



Lithological analysis of a core, 194 cm long, from the latitude of 9°S in the 

 eastern equatorial Pacific showed the occurrence of alternating layers of 

 Glohigerina ooze, red clay and sediments of intermediate type (Hough, 1953). 

 The top 24 cm consist largely of "medium dark brown lutite". Red-clay layers 

 one to a few centimeters thick with interbedded Glohigerina ooze occur between 

 24 and 44 cm below the top, between 102 and 114 cm, and from 175 cm to the 

 bottom of the core. These intervals were interpreted as representing glacial 

 ages; and the intervening sections, containing white to medium brown oozes, as 

 representing interglacial ages (Hough, 1953). The correctness of this interpreta- 

 tion is not assured, because pure Glohigerina ooze occurs interbedded with red 

 clay in the supposedly glacial sections, and the postglacial section is represented 

 by "medium dark brown lutites" which are apparently closer to red clay than 

 to Glohigerina ooze. The detailed chronology published by Hough (1953) is of 

 uncertain validity. In fact the radium measurements by Urry (1949) on both 

 the Glohigerina-ooze and red-clay components did not yield the 230'jh decay 

 curves hoped for, and allow only the tentative conclusion that the bottom of 

 the core is some hundreds of thousands of years old (cf. Volchok and Kulp, 1957; 

 Rosholt et al., 1961). This difficulty, the obviously large amount of post- 

 depositional solution and the inadequate stratigraphic study of this core, make 

 it impossible to interpret the published stratigraphy in terms of Pleistocene 

 events. 



Four cores from north of the Ross Sea, ranging in length from 0.9 to 2.6 m, 

 show the occurrence of coarse glacial-marine sediments in the top 10-20 cm, 

 followed by fine, well sorted sediment a few decimeters thick. This is followed 

 in turn by various layers of alternating coarse to fine glacial-marine sediments 

 (Hough, 1950; Thomas, 1959). As suggested or implied by Thomas (1959), it 

 seems likely that the very fine, well sorted sediments were deposited during 



