5.9.1.2 the earth’s early atmosphere

Question 1

What has happened to the theories about what was in the Earth’s early atmosphere?

Answer 1

They have changed ad developed over time, evidence for the early atmosphere is limited because of the time scale of 4.6 billion years.

Question 2

One theory suggests…

Answer 2

That during the first billion years of the Earth’s existence there was intense volcanic activity that released gases that formed the early atmosphere and water vapour that condensed to form oceans.

Question 3

At the start of this period the Earth’s atmosphere may have been like..

Answer 3

The atmospheres of mars and Venus today, consisting of mainly carbon dioxide with little or no oxygen gas.

Question 4

What do volcanoes produce

Answer 4

Nitrogen which gradually builds up in the atmosphere and there may have been small proportions of methane and ammonia.

Question 5

When the oceans formed what happened to carbon dioxide levels?

Answer 5

They decreased- carbon dioxide dissolved in the water and carbonates were precipitated producing sediments.

Question 6

Name something other than oceans which decreased carbon dioxide levels

Answer 6

Plantlife- Fungi and other small organic structures, consuming carbon dioxide and releasing oxygen