A sedimentary section 607.7 m thick extending from the Holocene to the lower Pliocene was recovered at Site 1096. Sedimentation rates were calculated for the upper 569 mbsf over intervals of continuous recovery. The depth-age relationship (Fig. F53; Table T33) was based on diatom and radiolarian datums in combination with geomagnetic reversals from Holes 1096A, 1096B, and 1096C. Sedimentation rates are assumed to be constant between geomagnetic reversals and are calculated by taking the slope of the depth-age line between successive points (Fig. F54; Table T34). By extrapolation, the age of the base of the hole (607.7 mbsf) was estimated as 4.7 Ma.
The depth of a magnetic polarity transition is defined as the depth at which the inclination changes sign. Many transitions were assigned a large uncertainty where the transition itself was lost in a gap between cores or within a disturbed interval (see Table T21; Figs. F24, F25). The center of the uncertainty interval was used in calculating sedimentation rates. Biostratigraphic datums were assigned when a clear FO or LO could be determined through examination of sediment samples. No FO or LO was determined when the occurrence bordered an interval barren of biogenic material.
Calcareous nannofossils were present in the upper 170 mbsf at this site, but the relatively short intervals in which they occurred alternated with barren intervals, making it impossible to assign depths to any datums. Siliceous biostratigraphic datums (Table T33), which mostly occur in the lower 437 m of Site 1096, were less abundant than in Site 1095.
Depth-age relationships based on paleomagnetic data show two main intervals with different slopes (Fig. F53). From the bottom of the hole to a depth of 216 mbsf (2.58 Ma), the sedimentation rate averages ~18 cm/k.y. From 216 mbsf to the top of the hole, the sedimentation rate is ~9 cm/k.y. This upper interval is not as well constrained as the lower because of the absence of a clearly defined Matuyama reversed polarity chron (see "Paleomagnetism").