Reference Work Entry

Beaches and Coastal Geology

Part of the series Encyclopedia of Earth Science pp 728-733

Sea level curves

  • Nils-Axel MÖRner

The present sea level is a function of the geoid or equipotential surface of the earth's gravity field. The geoid relief amounts to several tens of meters. Further, it is the function of local effects such as the major wind pattern, major currents, and density variations due to salinity and temperature. The past sea level is the function of: global glacial volume changes (glacioeustasy) due to global climatic changes; ocean basin volume changes (tectonoeustasy) due to earth movements; and ocean level distribution changes (geoidoeustasy) due to geoid changes (Mörner, 1976a). Then too, it is influenced by changes in local meteorological, hydrological, and oceanographic factors. The present position of past shorelines is the function of crustal activity: isostasy and tectonism. In some areas, there is a secondary effect from compaction.

A sea level curve is a graph with the past sea level depth and/or elevation plotted against time. There are two main types of sea level curves: the relati ...

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