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Our Amazing Earth
Transcript of Our Amazing Earth
Our Amazing Earth
photo credit Nasa / Goddard Space Flight Center / Reto Stöckli
The Earth is constantly rotating on its own axis. It completes one rotation approximately every 24 hours.
Rotation and Revolution
As we now know the Earth is a sphere.
However there are a number of layers to this sphere that give shape to our Earth surface and are also responsible for some of the huge natural disasters we have.
Structure of the Earth
The Inner Core
As we know the Earths crust is made up of hard rock that floats on the mantle underneath.
Plate Tectonics Theory
However, this surface is not one whole piece joined together. It is cracked into different sections which we call plates.
These plates are constantly moving at a rate of up to 5cm per year.
There are 7 large and 12 smaller plates.
Some of the plate boundaries are difficult to define
Some plates are moving
each other. We call these
Some plates are moving
from each other. We call these
There are two types of plates.
Continental Plates are those on which the major land masses of the world sit.
These have an average thickness of 30-40km.
Oceanic plates are those which are found underneath the Earth's oceans.
These have an average thickness of 10km.
Which ones do you think move more quickly?
Other plates are
past each other in opposite directions.
We call these
The earth was not always this way
Since the plates have always been moving, the continents above them move as well.
It is believed that the continents used to fit together into one large land mass called
These plates then moved away from each other and eventually moved into the positions we see today.
This theory of movement is called ...
What is the Inner Core made of?
The inner core is in the centre and is the hottest part of the Earth. It is solid and made up of iron and nickel with temperatures of up to 5,500°C. With its immense heat energy, the inner core is like the engine room of the Earth.
The outer core is the layer surrounding the inner core. It is a liquid layer, also made up of iron and nickel. It is still extremely hot, with temperatures similar to the inner core.
The mantle is the widest section of the Earth. It has a diameter of approximately 2,900 km. The mantle is made up of semi-molten rock called magma. In the upper parts of the mantle the rock is hard, but lower down the rock is soft and beginning to melt.
The crust is the outer layer of the earth. It is a thin layer between 0-60 km thick. The crust is the solid rock layer upon which we live.
The Earth is also revolving around the sun. It does this once every 365 days (approximately).
It contains all the topics covered in the year 8 geography program, with some supporting material created by year 8 students.
This poster shows all this information
Watch this video to find out more about how rotation and revolution work
This video will explain the theory of plate tectonics
This Popplet shows the different ways the plates can move and what can be caused by these movements.
Natural disasters are naturally occurring events that cause damage and harm to humans and human environments.
The difference between a natural disaster and a natural hazard is....
A natural hazard is the event itself, like a volcano erupting. A natural hazard has the potential to cause damage to humans.
A natural disaster is when a hazard actually does cause damage to humans.
This Toondoo cartoon explains this difference.
All the plate movements have an effect on the way the Earth's surface looks. Particularly with the formation of mountains.
There are three ways in which mountains are formed.
1. Fold Mountains
These are formed when plates converge and force the crust to buckle and fold.
2. Fault Mountains
These are formed when plates diverge and cracks or faults are formed. These faults then drop down or are pushed up.
Faulting causes block mountains and rift valleys.
3. Volcanic Mountains
These are mountains formed by volcanic activity.
In other words they used to be volcanoes, but are now extinct and have been subject to weathering and erosion.
This video shows how these processes work
This is a movie the students have made to demonstrate fold and fault mountains