What Is Metamorphic Rock?
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This video from NASA shows how metamorphic rocks relate to the rock cycle.
NASA
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Here on Earth we have three basic types of rocks: igneous, sedimentary, and metamorphic rocks. Scientists classify these rocks
by the way they were made. Igneous rocks are formed when lava from a volcano cools and hardens. Igneous rocks are also formed
when magma cools below Earth’s surface. Sedimentary rocks are formed when the elements wear rocks down into tiny particles
of dust, sand, and soil. Wind and water help move these particles around and deposit them into layers. As time passes, these
layers are cemented together and harden into new rocks. Metamorphic rocks form when sedimentary or igneous rocks change after
being exposed to extreme heat or pressure without melting. As conditions on Earth change, rocks may change from one type to
another. Sedimentary rocks can change into metamorphic rocks, or, if they melt, into igneous rocks. Igneous rocks can change
into sedimentary or metamorphic rocks, and metamorphic rocks can change into sedimentary or igneous rocks. Scientists call
these changes “the rock cycle."
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Earth is made up of three kinds of rock, called igneous, sedimentary, and metamorphic. Like our planet, these rocks are always changing. Igneous and sedimentary rocks can change because of strong heat or pressure.
A new kind of rock is formed from this change. New rock that is formed from heat or pressure is called metamorphic rock.
Metamorphic rocks have been on Earth for millions of years. They can be different shapes, sizes, and colors. Metamorphic rocks
are used to make buildings, jewelry, powders, and other things. They are an important part of our world.
