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24 Cards in this Set
- Front
- Back
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What is the earths crust? |
Thin outer layer of solid rock - 20km |
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What is the mantle? |
Solid section between crust and core. Near the crust its rigid, deeper in it becomes like semi liquid |
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What is the core? |
Inner core is solid and outer core is liquid |
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What is the lithosphere? |
It's the crust and the upper part of the mantle and is made up of tectonic plates. It is cold and rigid. Over 100km thick in places |
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What creates a lot of the heat inside the earth? |
Radio active decay - which creates convection currents in the mantle - causing the plates of the lithosphere to move. |
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How fast do the tectonic plates move? |
2.5 cm per year |
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What can S waves travel through? |
Only solids |
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What can P waves travel through? |
Solids and liquids |
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What parts of the earth can S waves travel through? |
Mantle |
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What parts of the earth can P waves travel through? |
Mantle and core |
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What did Alfred Wegener hypothesise? |
He had a theory of 'continental drift' and said there had been 1 supercontinent (Pangea)
Africa and South America had previously been 1 continent. He found matching layers of rocks and fossils living in both the continents |
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How are volcanoes formed? |
The oceanic plate is forced under the continental plate - subduction. The oceanic crust is cooling at the edges of a tectonic plate so the edges shrink easily, pulling oceanic plate down. As the oceanic crust is pulled down it melts, and starts to rise. |
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How is igneous rock formed? |
When any sort of molten rock cools down and solidifies |
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What are the 2 types of magma and what makes them different? |
1. Iron rich basalt - it's runny and the eruption isn't explosive, so it's fairly safe. 2. Silica-rich rhyolite - the lava is thick and the eruption is usually explosive and violent |
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How could scientists predict an eruption? |
Monitoring magma movement, below the ground, near a volcano |
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What are the 3 steps in the formation of sedimentary rock? |
1. Layers of sediment are laid down in seas or lakes. 2. Over millions of years the layers get buried under more layers and the pressure squeezes out all the water. 3. Fluids flowing through the pores deposit natural mineral cement. |
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What type of rock is limestone and what is it formed from? |
Sedimentary & seashells |
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What are metamorphic rocks? |
They are formed by the action of heat and pressure on sedimentary rocks over long periods of time. |
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Give an example of a metamorphic rock? |
Marble - formed from limestone - very hard. |
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What is an example of igneous rock? |
Granite - very hard |
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How is glass made? |
By melting limestone, sand and soda together. |
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How are bricks made? |
Clay is dug up from the ground and moulded into the right shape. This is then hardened with high temperatures. |
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How is cement made? |
Powdered clay and powdered limestone are roasted in a rotating kiln. |
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How is concrete made? |
Cement is mixed with sand, aggregate and water to make concrete |
