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 sea, level, dry and/or land:
“Why is it we never get our bad medicine in small doses?”
—Edmund H. North, British screenwriter, and Lewis Gilbert. First Sea Lord (Laurence Naismith)
“Architecture might be more sportive and varied if every man built his own house, but it would not be the art and science that we have made it; and while every woman prepares food for her own family, cooking can never rise beyond the level of the amateur’s work.”
—Charlotte Perkins Gilman (1860–1935)
“She is foremost of those that I would hear praised.
I will talk no more of books or the long war
But walk by the dry thorn until I have found
Some beggar sheltering from the wind, and there
Manage the talk until her name come round.”
—William Butler Yeats (1865–1939)
“If a man own land, the land owns him.”
—Ralph Waldo Emerson (1803–1882)