Sedimentology studies the properties, origins, and historical interpretation of sediments and sedimentary rocks. Such materials are formed by physical, chemical, and biological processes. More than 75 per cent of the earth's land surface is covered by sediments and sedimentary rocks. Near-surface sediments constitute the reservoirs for almost all groundwater, and are vitally important substrates for soils, wetlands, and shallow marine environments, while more deeply buried sediments provide most of the world's reserves of fossil fuels. The study and understanding of sediments and sedimentary rocks is therefore strongly multidisciplinary, and forms part of several academic disciplines (such as geology, geomorphology, stratigraphy, and civil engineering). This encyclopedia, which constitutes a wide ranging and authoritative collection of academic articles, covers the sedimentological aspects of sediments and sedimentary rocks.