How long ago did the earth form?

About 4.6 billion years ago.

Answer in your head, out loud, or on paper, then tap the card to flip.

What is the composition of our current atmosphere (approximately what percentage is each gas)?

78% nitrogen, 21% oxygen, 1% argon, <1% all other gases.

Answer in your head, out loud, or on paper, then tap the card to flip.

What are the 3 main stages in the evolution of Earth's atmosphere?

Phase 1 - volcanoes emitted large amounts of gas.

Phase 2 - earth cooled, oceans formed, plants and algae evolved.

Phase 3 - plants and algae produced oxygen, eventually forming the atmosphere we have today.

Answer in your head, out loud, or on paper, then tap the card to flip.

What happened to Earth's atmosphere in the first billion years?

The Earth's surface was very volcanic, releasing lots of carbon dioxide and nitrogen, alongside smaller amounts of water vapour, ammonia, and methane.

Answer in your head, out loud, or on paper, then tap the card to flip.

How were oceans formed?

After 1 billion years, the earth cooled, causing water vapour in the atmosphere to condense into liquid and form the oceans.

Answer in your head, out loud, or on paper, then tap the card to flip.

What happened to most of the carbon dioxide in the early atmosphere?

  1. It dissolved in oceans.
  2. The dissolved CO2 then went through a series of reactions to form carbonate precipitates.
  3. These carbonate precipitates formed sediments on the sea bed.
  4. Some CO2 was also absorbed by green plants and algae so they could photosynthesise.

Answer in your head, out loud, or on paper, then tap the card to flip.

What is limestone made from?

Limestone is made from calcium carbonate deposits from the shells and skeletons of marine organisms.

Answer in your head, out loud, or on paper, then tap the card to flip.


When did algae start producing oxygen?

About 2.7 billion years ago.

Answer in your head, out loud, or on paper, then tap the card to flip.

Why is evidence for the earth's early atmosphere limited?

It was a very long time ago (over 4.6 billion years ago), so there is little evidence remaining.

Answer in your head, out loud, or on paper, then tap the card to flip.

How are coal, crude oil, and natural gas formed?

  1. Plants or algae absorb CO2 to use in photosynthesis.
  2. When they die they don't decompose properly.
  3. Under high temperatures and pressures, the organic material forms coal, crude oil, or natural gas.

Answer in your head, out loud, or on paper, then tap the card to flip.

How has the atmosphere changed since the earth was formed?


(6 steps)

  1. Volcanos released large amounts of nitrogen and carbon dioxide, alongside smaller amounts of water vapour, methane and ammonia.
  2. As the earth cooled the water vapour condensed to form the oceans. 
  3. Carbon dioxide dissolved in oceans to form carbonates.
  4. Carbonates produced sediments which formed sedimentary rock.
  5. Algae and plants appeared and absorbed carbon dioxide by photosynthesis, releasing oxygen.
  6. Carbon was locked up in fossil fuels.

Answer in your head, out loud, or on paper, then tap the card to flip.

What is the word equation for photosynthesis?

carbon dioxide + water ➔ oxygen + glucose

Answer in your head, out loud, or on paper, then tap the card to flip.