atmosphere by Annemarie Roesch

4.6 billion years ago (bya)

roeschap27 — 2025-07-09 15:40:44 UTC

Earth’s atmosphere was made of gases like hydrogen, methane, ammonia, and water vapor from volcanic eruptions there was no oxygen.

4.0 billion years ago (bya)

roeschap27 — 2025-07-09 15:42:32 UTC

Volcanoes kept adding gases, but cyanobacteria (blue green algae) began using sunlight to make food and released oxygen into the water and air.

2.6 billion years ago (bya)

roeschap27 — 2025-07-09 15:43:55 UTC

Oxygen levels rose slowly. Iron in the ocean reacted with oxygen and formed rust on the seafloor, and the ozone layer began forming in the sky.

400- 290 million years ago (mya)

roeschap27 — 2025-07-09 15:45:29 UTC

Green plants became common on land and made even more oxygen. The ozone layer got stronger, which protected life from UV rays, helping animals move onto land.

290 mya- present day

roeschap27 — 2025-07-09 15:47:09 UTC

Oxygen levels stayed stable, supporting a variety of life. Humans and animals now depend on the balance of gases in the atmosphere, but pollution threatens this balance.