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What are rocks ppt
 

What are rocks ppt

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    What are rocks ppt What are rocks ppt Presentation Transcript

    • The Rock Cycle
      • What are rocks?
        • Rocks are made of grains that fit together
        • Grains can be different colours, shapes and sizes
        • Rocks with rounded grains more likely to absorb water - porous
    • Weathering
      • Three types of weathering
      • Physical Weathering
      • Biological Weathering
      • Chemical Weathering
    • Physical weathering
      • caused by physical change like temperature or effects from the wind.
    • Biological weathering
      • animal and plants can wear away rocks
    • Chemical weathering
      • rainwater is naturally acidic because of the carbon dioxide from the air dissolves in it. Minerals in rocks may react with rainwater, causing the rocks to be weathered.
    • Three main types of rocks
      • Sedimentary
      • Igneous
      • Metamorphic
    • Sedimentary Rocks
      • Formation
        • river carries or transports, pieces of broken rock as it flows along and then settles to the bottom and the rocks are deposited.
        • The deposited rocks build up in layers, called sediments = sedimentation.
      • Weight of sediments on the top squash the sediments on the bottom = compaction
      • Water is squeezed out from between the pieces of rock and crystals of different salts form
      • The crystals forms a sort of glue that sticks the pieces of rock together = cementation
    • Examples of sedimentary rocks
        • Chalk
        • Limestone
        • Sandstone
        • shale
    • Igneous Rocks
      • Inside the earth is very hot – hot enough to melt rocks.
      • Molten rock forms when rocks melt = magma
      • When the magma cools and solidifies, igneous rocks are formed
    • Examples of Igneous Rocks
      • Basalt
      • Granite
      • Obsidian
    • Metamorphic rocks
      • They are formed from other rocks that are changed because of heat or pressure
      • Earth movements can cause rocks to be deeply buried or squeezed. Therefore they are heated and put under pressure
    • When metamorphic rocks are formed under pressure, its crystals are arranged in layers
    • Examples of Metamorphic rocks
      • Slate is formed from shale
      • Marble is formed from limestone