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Oxygen began building up in the atmosphere at approximately 1.85 Ga. At current rates of primary production, today's concentration of oxygen could be produced by photosynthetic organisms in 2,000 years. [ 4] In the absence of plants, the rate of oxygen production by photosynthesis was slower in the Precambrian, and the concentrations of O 2 ...
Landmass. A landmass, or land mass, is a large region or area of land that is in one piece and not broken up by oceans. [1] [2] The term is often used to refer to lands surrounded by an ocean or sea, such as a continent or an island. [3] [4] In the field of geology, a landmass is a defined section of continental crust extending above sea level.
Earth is the third planet from the Sun and the only astronomical object known to harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all of Earth's water is contained in its global ocean, covering 70.8% of Earth's crust.
Sensor readings seemed to show that oxygen was being made on the seabed 4,000 meters (about 13,100 feet) below the surface, where no light can penetrate. The same thing happened on three ...
About 0.9% of the Sun's mass is oxygen. [18] Oxygen constitutes 49.2% of the Earth's crust by mass [68] as part of oxide compounds such as silicon dioxide and is the most abundant element by mass in the Earth's crust. It is also the major component of the world's oceans (88.8% by mass). [18]
The Great Oxidation Event ( GOE) or Great Oxygenation Event, also called the Oxygen Catastrophe, Oxygen Revolution, Oxygen Crisis or Oxygen Holocaust, [ 2] was a time interval during the Earth 's Paleoproterozoic era when the Earth's atmosphere and shallow seas first experienced a rise in the concentration of free oxygen. [ 3]
Cosmic rays ionize nitrogen and oxygen molecules in the atmosphere, which leads to a number of chemical reactions. Cosmic rays are also responsible for the continuous production of a number of unstable isotopes, such as carbon-14, in the Earth's atmosphere through the reaction: n + 14 N → p + 14 C.
The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans ), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather features such as clouds and hazes ), all retained by Earth's gravity.