METHODS

All samples were processed by first oven drying (50°C) and then soaking in dilute Calgon solution for several hours to dissagregate the sediment. Dissagregated sediment was washed through a 150-µm mesh and oven dried at 50°C. If necessary, samples were split using a CARPCO microsplitter to obtain ~300 specimens of planktonic foraminifers. Otherwise all specimens of planktonic foraminifers were placed in a standard 60-square micropaleontological slide and scanned for occurrences. The relative abundance of individual species were estimated as follows:

A = abundant, >75 specimens;

C = common, 25-75 specimens;

F = few, 5-25 specimens; and

R = rare, <5 specimens.

Samples from Section 167-1021C-10H-2 were fixed to a standard 60-square micropaleontological slide based upon their designation as species. The taxonomies of Parker (1962, 1967) and Blow (1969) were used.

Core 167-1021C-10H was sampled every 15 cm for planktonic foraminifers. Occurrences were recorded for 27 categories from a total of 64 samples (Table 1). In general, dissolution was strong throughout this interval, and the recovered planktonic foraminiferal fauna is skewed toward dissolution-resistant forms. The dominant taxa throughout the core are Globigerina bulloides, Globorotalia inflata s.l., and dextral coiling Neogloboquadrina atlantica. Other less common taxa include Orbulina universa, Globigerina pseudobesa, Globigerina umbilicata, dextral coiling Neogloboquadrina pachyderma, Neogloboquadrina acostaensis, Globigerinita glutinata, and Turborotalita quinqueloba. Other taxa occur sporadically and are generally rare (Table 1, Table 2).

The occurrences shown in Table 1 and Table 2 are consistent with a mid-latitude temperate zone planktonic foraminifer fauna. G. bulloides dominates the fauna in almost all samples. N. atlantica (cool, subpolar form) alternates with G. inflata (warm, subtropical form). Because of the location of Site 1021 on the ocean side margin of the cool southward flowing California Current, the increases in G. inflata may indicate a weakening of the California Current and the influence of the warmer gyre waters to the west. Accordingly, increases in N. atlantica may indicate that a broader California Current bathed Site 1021 with cooler temperatures (Poore, 1999).