Few things remain static in natural systems and perhaps no better illustrated than by changes in the level of the ocean surface with respect to the land over Quaternary timescales. The position of sea level (ultimate base level) and changes of sea level over geological timescales represent important controls in the evolution of coastal environments, and as an agent of profound geomorphological and environmental change in adjacent landscapes. Sea level determines the lower limit of continental denudation, to which fluvial, aeolian and other weathering and erosional processes may lower the landscape. Sea level also determines the volume and nature of terrestrially derived sediment deposited within coastal environments, sediment sourced from the inner continental shelf and acts as a major control in the formation of sedimentary carbonates.