Metamorphic Rocks

Rocks formed by the action of heat and/ or pressure on any pre-existing rock.

They can be recognised easily as they are crystalline, all crystals are interlocking, and are layered as the crystals have a preferred orientation. Fossils and sedimentary structures are rare.

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Metamorphism occurs at temperatures over 200 degrees centrigrade. Metamorphic changes occur in the solid state, there is no melting.

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