Figure 2. Biostratigraphic summary of planktonic foraminifers and magnetostratigraphy during the last 2.15 m.y. in Hole 997A based on this study and the Leg 164 science party. Age of magnetostratigraphic scales and nannofossil datums are adopted from Berggren et al. (1995a, 1995b). The climatic curve is based on the occurrence of the Globorotalia menardii group and its correlation with the standard oxygen isotope stratigraphy and the G. menardii zones of Ericson and Wollin (1968). Wei (1993) proposed the correlation adopted here of nannofossil datums with magnetostratigraphy and oxygen isotope stratigraphy. Because he did not used the timescale of Berggren et al. (1995a, 1995b), we apply only the stratigraphic relationship among nannofossil datums, magnetostratigraphic boundaries, and isotope stages to our climatic curve. The climatic curve at this site is shown in Figures 2 through 12 and is tentatively used as a biostratigraphic indicator, although no oxygen isotope stratigraphy exists in Hole 997A.