What do scientists believe that the Earth's early atmostphere consisted of?

Brainyblonde

The atmospheric pressure on the surface of the Earth averages 101.325 kPa, with a scale height of about 6 km. It is 78% nitrogen, 21% oxygen, with trace amounts of other gaseous molecules such as water vapor. http://en.wikipedia.org/wiki/Earth#Atmosphere Jul 11 06, 3:13 PM

niale

Thanks, but i'm looking for what scientists believe the earth's EARLY atmostphere consisted of. Jul 11 06, 3:50 PM

What-A-Mess

Stages: The history of the Earth's atmosphere prior to one billion years ago is poorly understood, but the following presents a plausible sequence of events. This remains an active area of research. The modern atmosphere is sometimes referred to as Earth's "third atmosphere", in order to distinguish the current chemical composition from two notably different previous compositions. The original atmosphere was primarily helium and hydrogen; heat (from the still molten crust, and the sun) dissipated this atmosphere. About 3.5 billion years ago, the surface had cooled enough to form a crust, still heavily populated with volcanoes which released steam, carbon dioxide, and ammonia. This led to the "second atmosphere"; which was, primarily, carbon dioxide and water vapor, with some nitrogen but virtually no oxygen. (Though very recent simulations run at the University of Waterloo and University of Colorado in 2005 suggested that it may have had up to 40% hydrogen.This second atmosphere had ~100 times as much gas as the current atmosphere. It is generally believed that the greenhouse effect, caused by high levels of carbon dioxide, kept the Earth from freezing. http://www.reference.com/browse/wiki/Earth%27s_atmosphere http://www.reference.com/browse/wiki/Earth%27s_atmosphere Please remember that ALL of this is educated theory with limited evidence but very probable. Jul 11 06, 4:42 PM

zbeckabee

However, many modern scientists now believe that the Earth's early atmosphere consisted mostly of carbon dioxide and water vapor. http://www.scipeeps.com/Sci-Chemistry_Topics_G_-_Ha/Harold_Clayton_Urey.html Science believes that the Earth's early atmosphere consisted of gases such as methane, hydrogen, ammonia, and steam. These gases may have combined with electrical discharge from lightning (other energy sources are also possible) to produce organic compounds. Organic compounds, which include amino acids, are recognized as the building-blocks of life. http://godandscience.org/evolution/lifeonearth.html Jul 11 06, 4:44 PM

What-A-Mess

Like most scientific theories.....Based on one or a few mens guesses and subject to change at any minute. Maybe it was made up of Quatrotriticale? And the Earth overrun with Tribbles? Sounds plausable to me! Jul 12 06, 11:13 AM