Early Earth history

Earths core is a solid iron sphere about the size of the Moon. Surrounding the inner core, there is an outer liquid core that contains a nickel-iron alloy. Scientists think the iron core formed when multiple collisions during Earths early history resulted in enough heat to melt metals. In the molten state, the densest materials, including iron and nickel, settled to the center and became Earths core. The less-dense materials remained at the surface. As Earth cooled, the outer layers solidified, creating Earths mantle and crust. 

The early period of the Earth s history, around 3.8 1 billion years ago, is completely shrouded in darkness possible witnesses from this archaic period might help to cast some light. So we are looking for possible remains of the first primitive life forms on our planet—fossils, or to be exact, microfossils, which refers to the remains of living cells. What have survived are mainly only cell walls, which can be isolated from sedimentary rocks when the silicate-, sulphide- or carbonate-rich minerals are chemically dissolved away. The microfossils are found in the remaining carbon-containing residue, transparently thin platelets of which are prepared for microscopic studies. 

The early period of the Earth s history, known geologically as the Hadean, is associated with huge bombardment of the surface of the planet by meteors and comets. The sequence of events in the Earth s formation is shown in Figure 7.3, starting with the Hadean. Any volatile materials on the surface of dust grains or planetesimals deposited on the Earth will be removed and become part of the atmosphere, or more generally the volatile component inventory of the planet. 

Canfield, D.E. 2005. The early ] history of atmospheric oxygen Homage to Robert M. Garrels. Annual Reviews Earth Planetary Science, 33, 1-36. 

Early History.—The existence of tellurium was first indicated at the beginning of 1783 by Muller of Hermannstadt, whose experiments suggested that the mineral known as aurum paradoxwm (an auriferous native tellurium) contained a new element. Bergmann of Upsala in 1783 concluded that a new element had actually been isolated. In 1789 the element was discovered independently by Kitaibel, and this discovery was confirmed in 1798 by Klaproth of Berlin, who suggested the name tellurium (Lat., tellus, the earth).2 A systematic examination of the chemical behaviour and characteristics of the new element was first carried out by Berzelius in 1835.3... 

Atmospheric concentrations of carbon dioxide have varied naturally throughout Earth s history. Present C02 concentrations, however, are now higher than any seen in at least the past 450,000 years. Recent direct measurements combined with sampling of air trapped in polar ice cores shows that the recent rise in CO, correlates well with industrialization, which began in the early 1800s, as revealed in the following graph ... 

Hiyagon, H., Ozima, M., Marty, B., Zashu, S., Sasaki, H. (1992) Noble gases in submarine glasses from mid-oceanic ridges and Loihi seamount Constraints on the early history of the Earth. Geochim. Cosmochim. Acta, 56, 1301-16. 

Ozima, M., Podosek, F. A., Igarashi, G. (1985) Terrestrial xenon isotope constraints on the early history of the Earth. Nature, 315, 471 —4. 

The chemistry of the early history of the earth and other planets depends upon the cosmic abundance of the elements, the temperature of the accumulating planets and the gravitational fields which permit or prevent the escape of gaseous molecules and the properties of chemical substances under the conditions existing. Because of the detailed character of chemical evidence considerable information in regard to the early history can be deduced. [96]... 

Elsasser, W. M. Early History of the Earth. In Earth Science and Meteoritics. Ed. J. Geiss u. E. D. Goldberg. Amsterdam North-Holland Publ. Company 1963. 

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