To understand how and why the Earth's layers interact, we need to know what forces are acting on these layers and how the forces are being generated. A force can change the shape of an object, it can change the direction in which an object is travelling or speed it up or slow it down. The forces of gravity and magnetism play an important role in maintaining and changing our planet.
Earth's Magnet
Physicists know that magnetic fields are produced when electric charges move. The Earth's magnetic field is thought to be generated by the 'dynamo effect' of the liquid iron and nickel outer core being moved by convection and the spinning effect of the Earth.
Having a magnetic field surrounding the planet is essential for our existence. It protects us from some of the more harmful solar radiation. Charged particles in solar winds hit the Earth's magnetic field and become trapped. They can then only move along the field lines that lead into the Earth. As these energetic particles move into the atmosphere, they collide with oxygen and nitrogen moecules. These molecules absorb this energy and become 'excited'. They eventually realease energy as visible light. You can see this in the night sky as an aurora.
Earth's Magnet
Physicists know that magnetic fields are produced when electric charges move. The Earth's magnetic field is thought to be generated by the 'dynamo effect' of the liquid iron and nickel outer core being moved by convection and the spinning effect of the Earth.
Having a magnetic field surrounding the planet is essential for our existence. It protects us from some of the more harmful solar radiation. Charged particles in solar winds hit the Earth's magnetic field and become trapped. They can then only move along the field lines that lead into the Earth. As these energetic particles move into the atmosphere, they collide with oxygen and nitrogen moecules. These molecules absorb this energy and become 'excited'. They eventually realease energy as visible light. You can see this in the night sky as an aurora.
The magnetic field surrounding the planet also magnetises rocks as they are formed. Rocks contain minerals and nearly all minerals are influenced by magnetic fields. When a rock is heated to very high temperatures and then allowed to cool, its magnetic components line up along the Earth's magnetic field lines that present at its location. This information means that we can determine where rocks were formed.
Heat
The deeper you go into Earth, the greater the pressure generated by the weight of overlying rocks. Naturally occurring radioactive elements uranium, thorium and potassium are found in granite. The radioactive decay of these elements over millions of years releases heat energy.
There are accepted facts in science that scientists apply everywhere in the Universe. These are called laws. Scientific laws have been varified experimentally and are accepted as being true.
A law known as the second law of thermodynamics tells us that any heat generated below the Earth's surface will move towards regions that are cooler. This movement sets up a convection current where energy moves through the mantle towards the crust. Strong convection currents constantly move through the mantle, and therefore move heat towards the surface.
Questions
1. Describe two effects that the Earth's magnetic field has on us.
2. Heat energy generated below the Earth's surface drives convection currents. Where in your home would you find convection currents?
Scientifc Tools and Evidence
Scientists often cannot examine things of interest to them directly. For example, they cannot land on the Sun and examine its surface directly. They have to investigate it in indirect ways. The same applies with Earth. We can't drill to the centre of the Earth to see the core and mantle. We have to use other tools and gather data to find the answers to use other tools and gather data to find the answers to what is below the surface of the Earth.
There are two key principles in geology - uniformitarianism and superposition.
Uniformitarianism is a scientific principle (law) that suggests that landscapes develop over long periods of time through slow geologic processes. Often this pinciple is stated as: 'The past is the key to the present'.
Superposition says that where there are layers of rock, those lower down will be older than those near the top.
TASK 1
In a small group of four you are to use the Jigsaw strategy to learn about the following key points. Seismology, gravity maps, fossils and volcanic activity.
Each person in your group will choose a key point. They are to investigate the key point and then share with everyone else.
Extension Task
Halfway down a cliff face are some seashells and near the bottom are fossils of plants that only grew on land. How could you explain this observation?
Heat
The deeper you go into Earth, the greater the pressure generated by the weight of overlying rocks. Naturally occurring radioactive elements uranium, thorium and potassium are found in granite. The radioactive decay of these elements over millions of years releases heat energy.
There are accepted facts in science that scientists apply everywhere in the Universe. These are called laws. Scientific laws have been varified experimentally and are accepted as being true.
A law known as the second law of thermodynamics tells us that any heat generated below the Earth's surface will move towards regions that are cooler. This movement sets up a convection current where energy moves through the mantle towards the crust. Strong convection currents constantly move through the mantle, and therefore move heat towards the surface.
Questions
1. Describe two effects that the Earth's magnetic field has on us.
2. Heat energy generated below the Earth's surface drives convection currents. Where in your home would you find convection currents?
Scientifc Tools and Evidence
Scientists often cannot examine things of interest to them directly. For example, they cannot land on the Sun and examine its surface directly. They have to investigate it in indirect ways. The same applies with Earth. We can't drill to the centre of the Earth to see the core and mantle. We have to use other tools and gather data to find the answers to use other tools and gather data to find the answers to what is below the surface of the Earth.
There are two key principles in geology - uniformitarianism and superposition.
Uniformitarianism is a scientific principle (law) that suggests that landscapes develop over long periods of time through slow geologic processes. Often this pinciple is stated as: 'The past is the key to the present'.
Superposition says that where there are layers of rock, those lower down will be older than those near the top.
TASK 1
In a small group of four you are to use the Jigsaw strategy to learn about the following key points. Seismology, gravity maps, fossils and volcanic activity.
Each person in your group will choose a key point. They are to investigate the key point and then share with everyone else.
Extension Task
Halfway down a cliff face are some seashells and near the bottom are fossils of plants that only grew on land. How could you explain this observation?