Figure F10. Cenozoic radiolarian biostratigraphic zonation schemes tied to the geomagnetic polarity time scale (Berggren et al., 1995b) and the New Zealand stages, which were used during Leg 181. The gray shaded area spanning the interval 55.5-54.6 Ma indicates the current range of differing usages of the Paleocene-Eocene boundary (after Berggren et al., 1995, p. 139).