Paleoceanographic and marine paleoclimatic investigations commonly use deep, open-ocean sediments or coral reefs to establish a continuous record of past global environmental changes because they both contain living organisms that are very sensitive to climate variations. Foraminifera (microorganisms with calcium carbonate shells) in particular are very sensitive to changes in temperature and chemical composition of the ocean. When conditions change, the organisms die, fall to the bottom of the sea, and become encased in sediments, therefore fossilizing information on past conditions. Continental margin records are more difficult to study than open-ocean records because continental margins are the receptacles of large amounts of sand, silt, and clay that dilute the microfossil concentration in the sediment. In addition, sea-level oscillations during the Quaternary exposed a large portion of shelves to continental erosion. Continental margins are therefore the subject of intense reworking by subaerial and submarine erosion. Thus, unlike deep, open-ocean records, sedimentary records from continental margins are often discontinuous, and deposits can be subject to post-depositional reworking by sedimentary processes.