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)
“We have found that morals are not, like bacon, to be cured by hanging; nor, like wine, to be improved by sea voyages; nor, like honey, to be preserved in cells.”
—William Cooke Taylor (1800–1849)
“Reduced to a miserable mass level, the level of a Hitler, German Romanticism broke out into hysterical barbarism.”
—Thomas Mann (1875–1955)
“I am renewed by death, thought of my death,
The dry scent of a dying garden in September,
The wind fanning the ash of a low fire.
What I love is near at hand,
Always, in earth and air.”
—Theodore Roethke (1908–1963)
“After all anybody is as their land and air is. Anybody is as the sky is low or high. Anybody is as there is wind or no wind there. That is what makes a people, makes their kind of looks, their kind of thinking, their subtlety and their stupidity, and their eating and their drinking and their language.”
—Gertrude Stein (1874–1946)