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:
“He who constantly swims in the ocean loves dry land.”
—Anton Pavlovich Chekhov (1860–1904)
“O you singers solitary, singing by yourself, projecting me,
O solitary me listening, never more shall I cease perpetuating you
Never more shall I escape, never more the reverberations,
Never more the cries of unsatisfied love be absent from me,
Never again leave me to be the peaceful child I was before what
there in the night,
By the sea under the yellow and sagging moon,
The messenger there aroused, the fire, the sweet hell within,
The unknown want, the destiny of me.”
—Walt Whitman (1819–1892)
“One of the peculiar sins of the twentieth century which we’ve developed to a very high level is the sin of credulity. It has been said that when human beings stop believing in God they believe in nothing. The truth is much worse: they believe in anything.”
—Malcolm Muggeridge (1903–1990)
“Have you not a moist eye, a dry hand, a yellow cheek, a white
beard, a decreasing leg, an increasing belly? Is not your
voice broken, your wind short, your chin double, your wit
single, and every part about you blasted with antiquity? and
will you yet call yourself young?”
—William Shakespeare (1564–1616)
“The great fact was the land itself, which seemed to overwhelm the little beginnings of human society that struggled in its sombre wastes. It was from facing this vast hardness that the boy’s mouth had become so bitter; because he felt that men were too weak to make any mark here, that the land wanted to be let alone, to preserve its own fierce strength, its peculiar, savage kind of beauty, its uninterrupted mournfulness.”
—Willa Cather (1873–1947)