Sea Level

The level of the surface of the sea; position of the air-sea interface, to which all terrestrial elevations and submarine depths are referred. Changes in the volume of water held in the sea and relative movements of the land surface, resulting from various types of deformation of the earth's crust are important in archaeology. Sea-level fluctuations are shown by deposits and landforms on the coasts of localities. The sea level constantly changes at every locality with the changes in tides, atmospheric pressure, and wind conditions. Longer-term changes in sea level are influenced by the Earth's changing climates. The sea level appears to have been very close to its present position 35,000 years ago.

The long-term level of the sea varies in two ways: (1) Changes in the volume of water held in the sea, known as eustatic sea level change; (2) Relative movements of the land surface, resulting from various types of deformation of the earth’s crust. Many such forms of crustal deformation are known, but in glacial terms the most important one is ISOSTASY. Evidence of such seal level variation during the Quaternary exists in a number of localities, notably the Mediterranean coasts — particularly Mallorca — and New Guinea. The most recent sea-level fluctuations are shown by deposits and landforms on the coasts of the Netherlands, the Baltic Sea, Scotland, northwest England and several other localities. Additional information is now coming from bore-holes in the beds of the North Sea and Irish Sea.