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The Rock Cycle
What are rocks?Rocks are made of grains that fit togetherGrains can be different colours, shapes and sizesRocks 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 rocksChalkLimestoneSandstone 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