The Rock Cycle
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The Rock Cycle is a group of changes.  Igneous rock can change into sedimentary rock or into metamorphic rock.  Sedimentary rock can change into metamorphic rock or into igneous rock.  Metamorphic rock can change into igneous or sedimentary rock.
Igneous rock forms when magma cools and makes crystals.  Magma is a hot liquid made of melted minerals.  The minerals can form crystals when they cool.  Igneous rock can form underground, where the magma cools slowly or above ground, where the magma cools quickly.
When it pours out on Earth's surface magma is called lava.  The same liquid rock that you see coming out of volcanoes.
On Earth's surface, wind and water can break rock into pieces  They can carry rock pieces to another place  Usually, rock pieces, called sediments, drop from the wind or water to make a layer.  The layer can be buried under other layers of sediments.  After a long time the sediment can be cemented together to make sedimentary rock.  Igneous rock can become sedimentary rock.
Did you know that all rock can be heated?  Where does the heat come from?  Inside the Earth there is heat from pressure.
Try this experiment.  Push your hands together very hard and you can feel heat.  Rub your hands together and feel the heat. (this is called friction)
What does heat do to rock?  It bakes the rock.  Baked rock doesn't melt but it does change.  If the rock has crystals already, it form larger crystals.  Because of the change in the rock it is called metamorphic.
When Earth's tectonic plates move around, they produce heat  When they collide, they build mountains and metamorphose the rock.
The rock cylce continues on.  Mountains made of metamorphoic rocks can be broken down and washed away by streams.  New sediments from these mountains can make new sedimentary rock.  The cycle never stops.

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