A chronology of Paleozoic sea-level changes

Sea levels have been determined for most of the Paleozoic Era ( 542 to 251 million years ago), but an integrated history of sea levels has remained unrealized. We reconstructed a history of sea- level fluctuations for the entire Paleozoic by using stratigraphic sections from pericratonic and cratonic basins. Evaluation of the timing and amplitude of individual sea- level events reveals that the magnitude of change is the most problematic to estimate accurately. The long- term sea level shows a gradual rise through the Cambrian, reaching a zenith in the Late Ordovician, then a short- lived but prominent withdrawal in response to Hirnantian glaciation. Subsequent but decreasingly substantial eustatic highs occurred in the mid- Silurian, near the Middle/ Late Devonian boundary, and in the latest Carboniferous. Eustatic lows are recorded in the early Devonian, near the Mississippian/ Pennsylvanian boundary, and in the Late Permian. One hundred and seventy- two eustatic events are documented for the Paleozoic, varying in magnitude from a few tens of meters to similar to 125 meters.