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MATERIALS FROM THE EARTH (Limestone and Thermal Decomposition (Limestone…
MATERIALS FROM THE EARTH
Sedimentary rocks
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Over millions of years the layers get buried under more layers and the weight pressing downs squeezes out the water.
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Limestone and Chalk
Limestone and chalk are sedimentary rocks and they contain fossils. The rock isn't formed at high temperatures - so the remains and imprints of dead organisms aren't destroyed.
Limestone and chalk are easily broken away by wind, rain and waves - this is called erosion and it can change the shape of our landscape
Metamorphic rocks
Metamorphic rocks are formed by the action of heat and pressure on sedimentary (or even igneous) rocks over long periods of time
Marble is formed from limestone and chalk. Very high temperatures break down the limestone and it reforms as small crystals. This gives marble a more even texture and makes it much harder
Igneous rocks
Igneous rocks form when molten magma pushes up into the crust (or right through it before cooling and solidifying. They contain various different minerals in randomly arranged interlocking crystals.
Extrusive Igneous rocks cool quickly above ground forming small crystals, e.g. basalt and rhyolite
Intrusive Igneous rocks cool slowly underground forming big crystals, e.g. granite and gabbro
Using Limestone
Limestone is the raw material used to produce other building materials, so it's quarried out on a large scale.
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You can then mix the cement with sand, water and gravel to make concrete
Limestone is also used to make glass. You just heat it with sand and sodium carbonate until it melts
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Advantages of Quarrying
Limestone provides things that people want - like houses and roads. Chemicals used in making dyes, paints and medicines also come from limestone.
Limestone products are used to neutralise acidic soil. Acidity in lakes and rivers caused by acid rain is also neutralised by limestone products.
Limestone is also used in power station chimneys to neutralise sulfur dioxide, which is a cause of acid rain.
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