Earths Early Atmosphere

Earth formed billions of years ago - thought to have been molten for millions of years.

Earth began to cool - motlen material formed land when cooled.

On that land volcanoes formed - they released gases into the earth through violent eruptions .

Earths gravity prevented gases escaping into space - they formed the atmosphere.

The atmosphere at that point in history is said to be the same as Venus and Mars's today.

 - They mainly consist of CO2.

Volcanoes formations led to gases being released into the air. 

When a volcanoe erupts it relases a mixture of N2, CO2, H2, H2O into the atmosphere.

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Igneous rocks - rocks formed by cooled solidified magma.

-  They contain interlocking crystals of different sizes.

-  Slower the rate = bigger the crystals 

-  Longer time allows for them to grow bigger.

-  The size of the crystal depends on the rate in which the magma is cooled.

Sedimentary Rocks - Rocks formed form other pieces of rock / hard parts of dead organisms.

-  Formed from seashells mostly made of calcium carbonate ( e.g. chalk / limestone )

-  Layers of sediment build up on the sea bed and compact together over time.

-  May contain fossils.

Metamorphic Rocks - Rocks formed by heating and/or pressuring existing rocks.

- Marble is formed from chalk or limestone.

- The small gaps between grains become new crystals of calcium carbonate that interlock.

- Meaning that it is harded than chalk or limestone.

Sedimentary rocks are the most susceptible to erosion 

- Interlocking crystals make the rocks harder and less erodible.