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)
“Translation is entirely mysterious. Increasingly I have felt that the art of writing is itself translating, or more like translating than it is like anything else. What is the other text, the original? I have no answer. I suppose it is the source, the deep sea where ideas swim, and one catches them in nets of words and swings them shining into the boat ... where in this metaphor they die and get canned and eaten in sandwiches.”
—Ursula K. Le Guin (b. 1929)
“If there is a price to pay for the privilege of spending the early years of child rearing in the driver’s seat, it is our reluctance, our inability, to tolerate being demoted to the backseat. Spurred by our success in programming our children during the preschool years, we may find it difficult to forgo in later states the level of control that once afforded us so much satisfaction.”
—Melinda M. Marshall (20th century)
“Since time immemorial, one the dry earth, scraped to the bone, of this immeasurable country, a few men travelled ceaselessly, they owned nothing, but they served no one, free and wretched lords in a strange kingdom. Janine did not know why this idea filled her with a sadness so soft and so vast that she closed her eyes. She only knew that this kingdom, which had always been promised to her would never be her, never again, except at this moment.”
—Albert Camus 1013–1960, French-Algerian novelist, dramatist, philosopher. Janine in Algeria, in The Fall, p. 27, Gallimard (9157)
““The glacier knocks in the cupboard,
The desert sighs in the bed,
And the crack in the tea-cup opens
A lane to the land of the dead.”
—W.H. (Wystan Hugh)