Sea Level and Dry Land
Several terms are used to describe the changing relationships between sea level and dry land. When the term "relative" is used, it means change relative to a fixed point in the sediment pile. The term "eustatic" refers to global changes in sea level relative to a fixed point, such as the centre of the earth, for example as a result of melting ice-caps. The term "steric" refers to global changes in sea level due to thermal expansion and salinity variations. The term "isostatic" refers to changes in the level of the land relative to a fixed point in the earth, possibly due to thermal buoyancy or tectonic effects; it implies no change in the volume of water in the oceans. The melting of glaciers at the end of ice ages is one example of eustatic sea level rise. The subsidence of land due to the withdrawal of groundwater is an isostatic cause of relative sea level rise. Paleoclimatologists can track sea level by examining the rocks deposited along coasts that are very tectonically stable, like the east coast of North America. Areas like volcanic islands are experiencing relative sea level rise as a result of isostatic cooling of the rock which causes the land to sink.
On other planets that lack a liquid ocean, planetologists can calculate a "mean altitude" by averaging the heights of all points on the surface. This altitude, sometimes referred to as a "sea level", serves equivalently as a reference for the height of planetary features.
Read more about this topic: Eustatic
Famous quotes containing the words dry land, sea, level, dry and/or land:
“I know only one person who ever crossed the ocean without feeling it, either spiritually or physically.... he went from Oklahoma to France and back again ... without ever getting off dry land. He remembers several places I remember too, and several French words, but he says firmly, “We must of went different ways. I don’t rightly recollect no water, ever.””
—M.F.K. Fisher (1908–1992)
“As the shade went up
And the ambulance came crashing through the dust
Of the new day, the moon and the sun and the stars,
And the iceberg slowly sank
In the volcano and the sea ran far away
Yellow over the hot sand, green as the green trees.”
—John Ashbery (b. 1927)
“For him nor deep nor hill there is,
But all’s one level plain he hunts for flowers.”
—Unknown. The Thousand and One Nights.
AWP. Anthology of World Poetry, An. Mark Van Doren, ed. (Rev. and enl. Ed., 1936)
“I knew very well that this hope was chimerical. I was like a pauper who mingles fewer tears with his dry bread if he tells himself that at any moment a stranger will bequeath to him his fortune. We must all, in order to make reality more tolerable, keep alive in us a few little follies.”
—Marcel Proust (1871–1922)
“For four hundred years the blacks of Haiti had yearned for peace. for three hundred years the island was spoken of as a paradise of riches and pleasures, but that was in reference to the whites to whom the spirit of the land gave welcome. Haiti has meant split blood and tears for blacks.”
—Zora Neale Hurston (1891–1960)