The primitive atmosphere which appeared as a result of the internal elemental contest between the heated interior and the cooling crust.  Terrestrial atmosphere slowly evolving between one billion to one and a half billion years ago.  The high degree of carbon in the atmosphere afforded the new land varieties of life opportunity for speedy and luxuriant growth.  The elevation of the continents proceeded, and the atmosphere was becoming enriched with oxygen. 
Were it not for the “blanketing” effect of the atmosphere at night, heat would be lost by radiation so rapidly that life would be impossible of maintenance except by artificial provision.  The height of the earth’s atmosphere is indicated by the highest auroral streamers—about 400 miles.