Volcanoes early Earth

FIGURE 1.3 Formation of biomolecules on the early Earth. Conditions on early Earth would have been inhospitable for most of today s life. Very little or no oxygen (O ) existed. Volcanoes erupted, spewing gases, and violent thunderstorms produced torrential rainfall that covered the Earth. The green arrow indicates the formation of biomolecules from simple precursors. 

Conclusions about the atmospheric composition of the early earth have been drawn from the gas exhalations of the so-called Hawaiian volcanoes type (Table 2.6). Oxygen is almost entirely missing from volcanic exhalations. Where O2 is... 

Mt. Early (2,720 m) in Fig. 16.43 is located south of Mt. Weaver at the head of the Scott Glacier in the Queen Maud Mountains. It is the most southerly volcano on Earth located at 87°04 S and 153°46 W. Although Mt. Early was discovered in 1934, it was first described by G.A. Doumani and V.H. Minshew who worked in the area during the 1962/63field season (Section 10.4.2 Doumani and Minshew 1965). Mt. Early was visited again during the 1978/79 field season by a geological field party led by E. Stump (Stump et al. 1980). 

It seems imlikely that the Earth kept much of its earliest atmosphere drrring early accretion, thus the primordial atmosphere would have been derived from outgassing of the planet s interior, which is thought to have occurred at temperatures between 300 to 1500° C. Modem volcanoes emit a wide range of gas mixtures, most of which is CO2 and SO2, rather than CH4 and H2S. However, it seems likely that most of the gases released today are from the reactions of reworked crastal material and water, and do not represent components of the Earth s deep interior. Thus modem volcanic gases may tell us little about the early Earth s atmosphere. 

There is a small non-biological source of methane, from serpentinization reactions in hydro-thermal systems around volcanoes, especially mid-ocean ridge systems (Holm Charlou 2001 Kelley et al. 2001). Early in the Earth s history this flux may have been greater, though still very small in comparison with modern biogenic fluxes. 

In addition, alternative hypotheses to Oparin s place the synthesis of prebiotic molecules in the hot, dry atmosphere of early volcanoes rather than the oceans (there are some laboratory xperiments showing that peptides and small proteins can be ibiotically synthesized under these conditions). Some still main- ain, like the astronomer Fred Hoyle, that the earth was seeded ... 

It is generally believed that the solar system condensed out of an interstellar cloud of gas and dust, referred to as the primordial solar nebula, about 4.6 billion years ago. The atmospheres of the Earth and the other terrestrial planets, Venus and Mars, are thought to have formed as a result of the release of trapped volatile compounds from the planet itself. The early atmosphere of the Earth is believed to have been a mixture of carbon dioxide (C02), nitrogen (N2), and water vapor (H20), with trace amounts of hydrogen (H2), a mixture similar to that emitted by present-day volcanoes. 

The hydrosphere is thought to have been formed by outgassing of steam from volcanoes during the early life of Earth. Although the mass of the current hydrosphere is effectively unchanging, water rapidly cycles between reservoirs (Table 21.2). More water is evaporated from the oceans than falls on them as precipitation, and more water falls as precipitation on the land masses than is evaporated. The system is balanced by river runoff. Most of the evaporation occurs from the tropical oceans, where the water vapor is carried to the ITCZ. Here it is uplifted in rising convective systems, where it precipitates in intense... 

What was there on the early pre-life Earth There was the atmosphere, water, and land. And there was certainly light coming from the Sim. Violent processes were occurring winds blew, waves battered, rivers rushed, thunder and hghtning rent the air, and volcanoes exploded The atmo-... 

Microbial cells were the first living cells on earth. They appeared about three and a half thousand million years ago as the starting point of the evolution of life on our planet. Microfossils that have been found in flint and certain other very fine sediments are regarded as direct proof of such early life — of cyanobacteria, for example, which probably formed a blue-green slime in the littoral regions of lakes close to volcanoes. 

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