Book excerpt: After a brief introduction to the distribution of deep-sea sediments, we show how the activities of marine organisms cycle nutrients and other dissolved constituents within the oceans, and influence the rates at which both solid and dissolved material is removed to sediments. Chapter 3 reviews the carbonate system and ends with a brief excursion into palaeoceanography. We conclude by describing the biological and chemical processes that continue long after sediments have been deposited on the deep-sea floor.