YEAR 7 GEOGRAPHY FOR EID

What is a volcano?

•The aim for this lesson is to make sure you can explain what a volcano is and identify its different parts.

•This work will also help you improve your geographical skills by giving you the opportunity to produce an annotated diagram.

•An annotated diagram has labels which identify a feature and give the reader extra information about the feature.

Task 1
• Read the first paragraph on page 32 of NKGI. This paragraph gives you a detailed explanation of what a volcano is.
Now look back to your work on the different types of plate boundaries.
You should make sure you can explain how a volcano is formed as a result of the movement of the plates.
Look especially at the CONSTRUCTIVE plate boundary.

Task 2
•Look at diagram A on page 32. The diagram is a cross-section of a volcano.
•This cross-section shows what you could see if you cut down through a volcano to expose the inside.
•Notice first the shape of the volcano....it is the shape of a CONE.
• Notice the different parts of the volcano...

The parts of the volcano 1
•Underneath the volcano, deep inside the crust we find the magma chamber.
•The magma chamber contains a store of magma , one of the materials that helps to build a volcano.
•Magma is the partly melted rock which rises up from the mantle. Remember the mantle is the next layer underneath the crust.

The parts of the volcano 2
•The magma rises up through the crust by means of the vent. Look at the vent on the diagram and see how it is connected to the magma chamber.
•The vent is simply a crack or gap in the earth’s crust, through which the magma can escape. Remember the plates can pull apart to make a gap.

The parts of the volcano 3
•Notice leading off from the main vent are smaller vents.
•These smaller vents are created if the main vent is blocked and the magma is still trying to force its way out. It takes an alternative route.
•As the magma makes its way to the surface along these smaller vents, secondary CONES are formed.

The parts of the volcano 4
•Look at the top of the volcano. There is a large circular hole. It is called the CRATER. A crater might be a few hundred metres across or even a few kilometres across!!
•Now look at the sides of the volcano. It builds up over time in layers....usually formed from lava and ash.

Task 3
•Think about what happens when the magma
escapes?
•When the magma forces its way out of the volcano it can be seen in different ways.
•Lava is the partly melted (molten) rock that flows out .

Pyroclastics
•Pyroclastics are materials that are thrown into the atmosphere by volcanoes. These include:
•Ash - the small pieces of rock thrown out.
•Dust particles that may be thrown out.
•Volcanic bombs - large pieces of partly melted rock that are thrown out. These can be as big as a very large television.
•Steam can also be produced from super-heated water that may be present.
•Gas is found naturally underneath the surface of the crust and can also escape out through the vent.

Task 4
•Now YOU have to produce an annotated diagram of the cross-section.
•You will be given a worksheet with a simple copy of the cross-section of a volcano.
•You must add a suitable title to the diagram.
•You must then add annotated labels around the outside of the diagram.

Annotated labels
•Remember an annotated label gives the name of something and extra information.
•You must label each part correctly and add suitable information to define what each part is or what it does.
•For example you could add the following label for the crater.

Example of an annotated label

Crater:
A circular opening at the top of a volcano.
Magma can escape out of the crater.


And to finish....
•Make sure you add suitable labels for all the other parts of the volcano.
•You should then colour the sketch carefully to make each part clear.
•Learn the words and their definitions before you come back to school.

•Good luck!