CONCLUSIONS

A review of the Palmer Deep studies to date highlights the following conclusions:

1. Palmer Deep does contain a sediment sequence with varved intervals, but the continuity of the time series is frequently interrupted by missing seasons (Nederbragt and Thurow, Chap. 3, this volume). This is probably due to the fact that Palmer Deep did not contain anoxic bottom waters and that summer productivity may have been suppressed by persistent pack ice.
2. Palmer Deep records a single glacial-to-Holocene sequence marked by distinctive climate intervals with both surface and deepwater changes in water temperature.
3. The most reasonable hypothesis that explains the changes in sediment and biotic characteristics is one that couples the ACC with the Southern Ocean and ENSO variability, most probably through westerly wind strength and southward migration of the ITCZ.
4. Alternative interpretations of sediment provenance and dilution effects remain unresolved within the middle Holocene to neoglacial transition.
5. The warmest sea-surface conditions were reached during the early to middle Holocene, as marked by subpolar diatom species.
6. Variations in phytoplankton composition beyond diatoms remain to be resolved, perhaps via biomarker studies.