Proportions of gases in atmosphere

• name 4 gases in the earths atmosphere

  nitrogen, oxygen, carbon dioxide, water
• give the proportions of gases in the earths atmosphere

  nitrogen- 80% oxygen- 20%, s
• why is evidence for the earths early atmosphere limited

  the timescale is 4.6 billion years
• what gases are believed to have been released from volcanoes during the first billion years of the earths existence

  nitrogen, carbon dioxide, water vapour, small amounts of ammonia and methane
• how do the oceans form

  water vapour in the atmosphere condensed
• why did the amount of carbon dioxide in the earlier atmosphere decrease

  when oceans formed carbon dioxide dissolved in the water, carbonates precipitated producing sediments, reducing carbon dioxide in the atmosphere
• what gas in the current day atmosphere was not present in the atmosphere 4.6 billion years ago


  oxygen