The age of earth has been computed to be about 4.6 billion years. The earth was initially supposed to have originated as a result of collapse and condensation of the interstellar clouds of gases and the dust, so called nebula. The present hypothesis proposed by Holy and Lyttleton (1939) suggested in to be a part broken off from the sun. It was though that: Originally the earth was a fiery spinning ball of hot gases, and vapours of various elements. The temperature was so high(about 5000-6000). The elements like hydrogen, oxygen, carbon and nitrogen could not exist in free state, rather they combined variously to form oxides, carbides, and nitrides. Water and ammonia were probably the first compound molecules of primitive earth. Hydrogen combine with oxygen, nitrogen and carbon forming water, ammonia, methane, and cyanides. The temperature being very high, the various compounds existed in gaseous state, while water occurred as superheated steam. This constituted the primitive atmosphere of the primitive earth. With the gradual decrease in temperature, the gases must have been changed into liquid and then in to solids , whereas steam must have condensed in to water, ultimately resulting into rains. The rains on reaching the superheated earth immediately evaporated to the atmosphere. The repeated rain cycle for millions of years resulted in to gradual but ultimate cooling of the earth surface and formation of large water bodies like oceans and seas.
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