The Earth

The three spheres of The Earth

atmosphere

hydrosphere

geosphere

The atmosphere is the layer of gases that surrounds the Earth

It consists mostly of nitrogen but also contains oxigen, carbon dioxide and other gases

The hydrosphere is all the water that exists on Earth

glaciers rain

riversoceans

groundwater

The geosphere is the part of the Earth that includes the rocks and minerals. They make landforms , such as mountains.

The atmosphere

What is the atmosphere?It’s the layer of gases that surrounds the Earth: Nitrogene, oxygen, carbon dioxide and others. It has different layers:

Troposphere (17 km)It’s the layer where living things are found. Contains weather systems (rain, wind)Most of the gases are in the troposphere

Mesosphere (85 km)It’s the coldest layer of the lower atmosphereThis layer protects the Earth from meteors

Outer layers of atmosphereOuter space

Stratosphere (50 km)Contains the ozone layer. The ozone layer absorbs ultraviolet light from the sun and reflects it back into space

troposphere

17 km

StratosphereOzone layer

Mesosphere

Outer layers of the atmosphere

Outer space

85 km50 km

The geosphere

What is the geosphere?

The geosphere is the solid part of the Earth. It’s made up of three spheres: The core, the mantle and the crust

crust

core

mantle

The crust is the outer layer and it’s made of rocks and minerals. It forms the continents, the islands and ocean floors. We can see landforms here: mountains, valleys

The mantle is the middle layer and contains a liquid rock called magma

The core is the inner sphere and it’s made of iron (liquid and solid). It’s the hottest part of the Earth

Earthquakes and volcanoes can change or move the crust

The wind, rain, ice and rivers can also change the Earth’s crust, very slowly.

This processes are called weathering and erosion

Weathering is the breaking down of rocks into smaller pieces

by plants or by animals

It can be caused by rain and freezing temperatures

Erosion is the moving of soil and rocks to a different place

Rocks and minerals

Rocks are made of one or more minerals

We can classify rocks into three groups:

• Sedimentary rocks: they are made of sediments (chalk)

• Metamorphic rocks: (marble)

• igneus rocks:

they form when liquid magma cools

• igneus rocks:

they form when liquid magma cools: (basalt)

• Metamorphic rocks: (marble)

There are thousands of minerals on Earth and we clasify them by their different properties: colour, hardness and lustre. Diamonds, galena, talc, are some examples of minerals

The hydrosphere

What is the hydrosphere?

The hydrosphere is all the water that exists on the Earth

solid

We can find water in three states

Liquid: saltwater and freshwaterOnly 1% of all the water

Gas: water vapour

A river starts in the source

It forms meanders

It ends at the mouth

The path of a river is called a course. We can divide the course into three parts: the upper course, the middle course and the lower course

Small rivers are called tributaries