The P/E boundary is marked by an abrupt contact between upper Paleocene nannofossil ooze and lower Eocene dusky red zeolite- and nannofossil-bearing clay that grades upward into nannofossil ooze (Zachos, Kroon, Blum, et al., 2004). The P/E boundary layer was recovered in Section 208-1266C-17H-3 at 306.8 meters composite depth (mcd). A 2.5-m-thick interval from Sections 208-1266C-17H-3 through 17H-2 was investigated for calcareous nannofossils. Semiquantitative investigations were carried out every centimeter across the P/E clay layer (from Sample 208-1266C-17H-3, 115–116 cm, to 17H-3, 84–85 cm), every 2 cm from Samples 17H-3, 149–150 cm, to 17H-3, 54–55 cm, and from this level upward from 3 to 20 cm.
Smear slides were prepared from unprocessed samples according to standard technical preparation methodology. Each smear slide was examined with a light microscope under 1250x magnification. Two traverses of each smear slide were checked for common and very rare species (Table T1). The relative abundance of each nannofossil taxon is defined as follows:
The total abundance of nannofossils in each sample as estimated as follows:
Preservation of nannofossils was recorded using the criteria of Steinmetz (1979) as good (G), moderate (M), and poor (P). Depths of samples in the range chart are reported in meters composite depth (Zachos, Kroon, Blum, et al., 2004).