ABSTRACT
Our understanding of Quaternary climate changes has been revolutionised by the study of sediments that have accumulated on the floors of the world's oceans. This is because ocean floor sediments generally provide a continuous record of sedimentation and only on rare occasions have they been disturbed by episodes of erosion. Such exceptions occur in areas where submarine landsliding and turbidity current activity have taken place. Sediments over much of the ocean floor consist predominantly of the skeletal remains of deposited calcareous and siliceous micro-organisms that have settled out of the water column. Most calcareous tests are dissolved below about 4 km water depth (the calcite compensation depth (CCD)) due to dissolution in the undersaturated water (Bradley 1985). As a result, most ocean cores used in palaeoenvironmental studies are taken from water depths shallower than approximately 4 km. Investigations of the undissolved species present within ocean sediment cores may therefore be used to reconstruct former patterns of environmental change.
