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.
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Famous quotes containing the words sea, level, dry and/or land:
“Thus to sea god,
gift of sea wrack;”
—Hilda Doolittle (1886–1961)
“Nihilism as a symptom that the losers have no more consolation: that they destroy in order to be destroyed, that without morality they no longer have any reason to “resign themselves”Mthat they put themselves on the level of the opposite principle and for their part also want power in that they compel the mighty to be their hangmen. This is the European form of Buddhism, renunciation, once all existence has lost its “meaning.””
—Friedrich Nietzsche (1844–1900)
“All cries are thin and terse;
The field has droned the summer’s final mass;
A cricket like a dwindled hearse
Crawls from the dry grass.”
—Richard Wilbur (b. 1921)
“What between the duties expected of one during one’s lifetime, and the duties exacted from one after one’s death, land has ceased to be either a profit or a pleasure. It gives one position, and prevents one from keeping it up. That’s all that can be said about land.”
—Oscar Wilde (1854–1900)