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13 Cards in this Set
- Front
- Back
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The Earths concentric layers and their properties.
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Inner Core:- This is the centre and also the hottest part of the earth, it's solid due to the pressure and is made up of iron and nickel.
Outer Core:- The outer core is almost as hot as the inner core, it too is made up of iron and nickel and is liquid. Mantle:- The mantle is the largest section of the Earth and is made up of semi-molten rock (magma) towards the crust the magma is hard but lower down it starts to melt. Crust:- The crust is the outer and thinest layer upon which we live. It's made up of to types of crust, continental which carries land and oceanic which carries water. |
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Plate Margins
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The Earths crust is broken up into plates. Convection currents, created by heat rising and falling in the mantle cause the plates to either converge (move towards each other) or diverge (move apart).
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Plate Boundaries
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The point at which two plates meet is the plate boundary, this is where earthquakes and volcanos occur.
There are four different types of plate margins: Destructive:- The plates move towards each other. Constructive:- The plates move apart. Conservative:- The plates slide past each other. Collision:- The plates push against each other to create fold mountains. |
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Destructive plate margins
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The denser oceanic plate is forced under the less dense continental plate. The point where this occurs is called the subduction zone. The denser plate is swallowed into the mantle where it melts. This then causes magma to rise which results in volcanos.
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Constructive plate margins
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As the plates move apart magma rises, depending on where this occurs, it could lead to an ocean ridge such as the mid-atlantic ridge. It could also lead to volcanos forming which eventually become islands.
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Conservative plate margins
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The plates move past each other and create fault lines on which earthquakes can occur because of a build up in pressure. These plates aren't smooth and so there are often points where 'snags' can occur causing the plates to jerk past each other.
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Collision plate margins
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When two continental crusts come together one doesn't slide under the other they both crumple up, which is how fold mountains are formed.
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Volcanos
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Volcanos are formed when molten rock reaches the surface of the earth and solidfies, creating a 'hill'.
There are two types of volcanos: Shield volcanos with gentle sloping sides, formed by eruptions runny lava. Composite volcanos with steep sides, usually found at constructive margins. They are formed by eruptions of viscous lava at destructive margins. They are made up of alternating layers of ash and lava. |
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Inside a volcano
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1) Magma chamber is located below the volcano.
2) Main vent is the main outlet for magma to escape. 3) Secondary vents are smaller outlets. 4) Crater's are created after an eruption when the top of a volcano is blown off. |
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Volcano key words and their meanings:
1) Pyroclastic flow 2) Lahar's 3) Magma 4) Lava |
1) A mixture of hot steam, ash, dust and rock. Erupted from composite volcanos.
2) A volcanic landslide/mudslide made up of a mixture of volcanic debris, mud, rock and water. 3) Hot molten rock found beneath the earth 4) Magma, but on the Earths surface. |
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Earthquakes and key features
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An earthquake is the shaking or vibrations in the Earths crust due to the movements of the plate boundaries. Pressure builds up and when it's released earthquakes will often occur. The point where this pressure is released is known as the focus. The point directly above this on Earths surface is called the epicentre. Earthquake vibrations are known as seismic waves and they are measured using a richter scale.
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Fold Mountains
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When there is an area of sea that separates two plates, sediment collect on the sea floor in depressions known as geosynclines. Overtime this sediment becomes compressed and forms sedimentary rocks.
When the two plates move towards each other again the layers of sedimentary rock on the sea floor crumple and fold upwards. Again overtime this will become visable above sea level as a range of fold mountains. |
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Fold mountain key features
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When the rocks are folded upwards they are called anticlines, when they are folded downwards they are called synclines.
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