Rocks and Earth’s atmosphere

Chemistry revision

In this lesson you will re-visit…

The three main types of rock

The Rock Cycle

Dating rock strata

Plate tectonics, convection cells

Evolution of the Earth’s atmosphere

You need to be able to:

Name the 3 types of rock and two examples of each.

Label a cross section of the Earth.

Be able to state how rocks can be dated by fossil evidence and igneous intrusion.

Describe the theory of plate tectonics.

Draw the simple diagram of a destructive and constructive plate margin.

Be able to describe the stages involved with Earth’s atmosphere evolution.

There are 3 types or rock

Can you name the 3 types from this diagram?

This is a link to other pupils work

Sedimentary rocksTend to be crumbly and sometimes contain fossils. They are laid down in layers – the particles of rock eventually cementing together. They are laid down by water and wind.

Here are two examples:

Sandstone Limestone

Igneous rocks

Igneous rocks are formed from molten rocks which have cooled and solidified. Below the Earth’s surface molten rock is called magma, on the surface it is lava.

This rock is hard and has crystals. Crystal size depends on how quickly the rock cooled.

Here are two examples:

Granite

Granite BasaltWhat can you say about how they cooled?

Metamorphic rocksThere are rocks formed by high temperature and pressure on existing rocks. They are hard and may contain banded crystals.

Here are some examples:

This is gneiss This is marble

Clues in the Rocks

The Rock Cycle – rocks are continually being broken down and reformed into new rocks.

Can you label the process arrows?

How to find out the history of rocks

Igneous rocks can give useful information about the geological history of an area. This can be used to date the age of the rocks. Look at this diagram.

Can you explain what is going on?Sedimentary

rocks laid down firstIgneous rock

intruded later on so is YOUNGER.

Plate tectonics – how the earth moves

Convection currents in the mantle move the rigid crust plates.

Plate boundaries

These plates have two types of movement

A constructive boundary

A destructive boundary

The evolution of the Earth’s atmosphere

Phase 1

The Earth was molten and volcanic for many millions of years. Any gases boiled away.

Loads of carbon dioxide, steam, ammonia and methane were given out.

Phew, stinky or what!

Phase 2Phase 2Phase 2

Water vapour condensed and formed oceans. The water also absorbed carbon dioxide.

Plants evolved – they really liked the carbon dioxide atmosphere.

Carbon dioxide got wrapped up in fossil fuels and sedimentary rocks like limestone.

Phase 3Phase 3Because of plants, lots of oxygen built up in the atmosphere – it is so poisonous many organisms died!

Oxygen also created the OZONE layer, though poisonous, stopped harmful UV killing us off!

BUT, this allowed more complex organisms to evolve..

So can you….Describe how the 3 types of rock are formed and give examples of each?

Fill out a partially completed Rock Cycle?

Explain why some continents have similar fossils and rock types but are far apart?

Draw simple diagrams of a constructive and destructive plate boundary?

Explain how the Earth’s atmosphere has changed over millions of years?