The Earth's Atmosphere in the Past Flashcards
When do scientists think the Earth was formed?
4.5 billion years ago
What was the earth’s early atmosphere formed by?
Volcanic activity
In the first billion years, what was the surface covered with?
Volcanoes that released carbon dioxide, water vapour and nitrogen
What happened when the earth cooled?
Most of the water vapour condensed into oceans
What was the early atmosphere mostly formed of?
Carbon dioxide and water vapour
What do some scientists also think there was in the early atmosphere?
Nitrogen, methane and ammonia
What happened in the next two billion years?
Bacteria, algae and plants evolved
What did algae and plants do?
Used carbon dioxide for photosynthesis and released oxygen
What happened as the number of plants increased?
The amount of oxygen increased and the amount of carbon dioxide in the atmosphere decreased
