Question
Write short notes on :
1. Origin of the atmosphere.
Solution
Today’s atmosphere is the result of very gradual changes starting about 5 billion years ago, by accretion of cold particles, chiefly of iron and magnesium, silicate iron and graphite. Then the earth was too small to retain the primordial atmosphere of light gases. Gravitational collapse and radioactive decay caused earth to heat up and the materials differentiated giving central solid nickle-iron core, liquid iron silicate shell mantle and lithosphere. In this way degassing took place forming a new atmosphere and hydrosphere.
