Barystatic sea-level changes—glacial–interglacial cycles

The Quaternary Period has repeatedly witnessed major changes in barystatic (formerly termed glacio-eustatic) sea level resulting from fluctuating ice volumes in response to insolation changes registered at the surface of the Earth. The timing and magnitude of these barystatic changes has conformed to a generally consistent pattern in space and time as revealed in oxygen isotope records from marine and ice cores, and corroborated by geomorphological and stratigraphical evidence from the World's coastlines. At a broad scale since at least the start of the Middle Pleistocene, barystatic sea-level variations have occurred as part of glacial cycles. These cycles have seen the slow and progressive build up of continental-scale ice sheets, and concomitant sea level lowering by as much as 130–120 m over a time span close to 100 ka. Seven glacial cycles have occurred since the start of the Middle Pleistocene some 781 ka ago. Glacial cycles of the Early Pleistocene involved lower amplitude sea-level fluctuations and over shorter periods (41 ka cycles).