Water in The Development of The Earth
See also: Planetary differentiationA sizeable quantity of water would have been in the material which formed the Earth. Water molecules would have escaped Earth's gravity more easily when it was less massive during its formation. Hydrogen and helium are expected to continually leak from the atmosphere, but the lack of denser noble gases in the modern atmosphere suggests that something disastrous happened to the early atmosphere.
Part of the young planet is theorized to have been disrupted by the impact which created the Moon, which should have caused melting of one or two large areas. Present composition does not match complete melting and it is hard to completely melt and mix huge rock masses. However, a fair fraction of material should have been vaporized by this impact, creating a rock-vapor atmosphere around the young planet. The rock-vapor would have condensed within two thousand years, leaving behind hot volatiles which probably resulted in a heavy carbon dioxide atmosphere with hydrogen and water vapor. Liquid water oceans existed despite the surface temperature of 230°C because of the atmospheric pressure of the heavy CO2 atmosphere. As cooling continued, subduction and dissolving in ocean water removed most CO2 from the atmosphere but levels oscillated wildly as new surface and mantle cycles appeared.
Study of zircons has found that liquid water must have existed as long ago as 4.4 Ga, very soon after the formation of the Earth. This requires the presence of an atmosphere. The Cool Early Earth theory covers a range from about 4.4 Ga to 4.0 Ga.
In fact, recent studies of zircons (in the fall of 2008) found in Australian Hadean rock hold minerals that point to the existence of plate tectonics as early as 4 billion years ago. If this holds true, the previous beliefs about the Hadean period are far from correct. That is, rather than a hot, molten surface and atmosphere full of carbon dioxide, the Earth's surface would be very much like it is today. The action of plate tectonics traps vast amounts of carbon dioxide, thereby eliminating the greenhouse effects and leading to a much cooler surface temperature and the formation of solid rock, and possibly even life.
Read more about this topic: Origin Of Water On Earth
Famous quotes containing the words water in, water, development and/or earth:
“As must have rung the harvest-song of Linos
Of bloody water in a heap of stones.”
—Allen Tate (1899–1979)
“A man’s social and spiritual discipline must answer to his corporeal. He must lean on a friend who has a hard breast, as he would lie on a hard bed. He must drink cold water for his only beverage. So he must not hear sweetened and colored words, but pure and refreshing truths. He must daily bathe in truth cold as spring water, not warmed by the sympathy of friends.”
—Henry David Thoreau (1817–1862)
“Theories of child development and guidelines for parents are not cast in stone. They are constantly changing and adapting to new information and new pressures. There is no “right” way, just as there are no magic incantations that will always painlessly resolve a child’s problems.”
—Lawrence Kutner (20th century)
“You’ll never succeed in idealizing hard work. Before you can dig mother earth you’ve got to take off your ideal jacket. The harder a man works, at brute labour, the thinner becomes his idealism, the darker his mind.”
—D.H. (David Herbert)