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: Sea Level
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)
“Light breaks where no sun shines;
Where no sea runs, the waters of the heart
Push in their tides;”
—Dylan Thomas (1914–1953)
“Insurrection:... insurrection as soon as circumstances allow: insurrection, strenuous, ubiquitous: the insurrection of the masses: the holy war of the oppressed: the republic to make republicans: the people in action to initiate progress. Let the insurrection announce with its awful voice the decrees of God: let it clear and level the ground on which its own immortal structure shall be raised. Let it, like the Nile, flood all the country that it is destined to make fertile.”
—Giuseppe Mazzini (1805–1872)
“There is something about poverty that smells like death. Dead dreams dropping off the heart like leaves in a dry season and rotting around the feet; impulses smothered too long in the fetid air of underground caves. The soul lives in a sickly air. People can be slave-ships in shoes.”
—Zora Neale Hurston (1891–1960)
“The structure was designed by an old sea captain who believed that the world would end in a flood. He built a home in the traditional shape of the Ark, inverted, with the roof forming the hull of the proposed vessel. The builder expected that the deluge would cause the house to topple and then reverse itself, floating away on its roof until it should land on some new Ararat.”
—For the State of New Jersey, U.S. public relief program (1935-1943)