Evolution of the Atmosphere Flashcards

All 7 cards in this deck

What produced the gases that formed the Earth's early atmosphere?

Volcanic activity.

What is the Earth's early atmosphere thought to have contained?

Little or no oxygen, a large amount of carbon dioxide, water vapour, and small amounts of other gases (e.g. nitrogen, methane, ammonia).

How did the oceans form?

The Earth cooled, so water vapour condensed and fell as rain, forming the oceans.

Name two processes that removed carbon dioxide from the early atmosphere.

It dissolved in the oceans as they formed (later locked up in carbonate rocks and fossil fuels), and photosynthesis by primitive plants.

What does it suggest about the early atmosphere that the oldest rocks contain iron sulfide but no iron oxide, while later rocks contain iron oxide?

There was little or no oxygen at first; oxygen later increased, so iron was oxidised.

What is the chemical test for oxygen, and the positive result?

A glowing splint relights in the gas.

True or false? The increase in oxygen in the Earth's atmosphere was caused by volcanoes releasing oxygen.

False. It was caused by photosynthesis by primitive plants (and photosynthetic organisms such as algae/cyanobacteria).