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Metamorphic Rocks
By:
Joey Lewitin - [other]
Deep beneath the surface of the earth there is a place of heat and fire so extreme that the very stone of the planet melts beneath its pressures. This is where metamorphic rocks are formed.
Metamorphic rocks form out of igneouse, sedimentary, or other metamorphic rocks, during a process known as metamorphism. There are three types of metamorphism: Contact or heat based, regional which happens when pressure affects a wide area, and dynamic which occurs due to the movements of stone on stone.
Metamorphism occurs at 200 degrees celcius and about 3000 atmospheres of pressure.
As the temp becomes higher, the grade of metamorphism increases. Below 320 degrees celcius low grade metamorphism occurs. These rocks are generally high in hydrouse materials. High grade metamorphism occurs above this temperature and is much less hydrous.
Reverse metamorphism can occur, but doesn't happen very often. If it did we wouldn't see any metamorphic rocks at the surface of the earth, because as they rose they would turn back into their components. The rocks we do see are formed deep beneath the earth, where the temperatures are high enough to cause metamorphism. The process is very slow, and it is also very slow for the rocks to rise back to the surface of the planet.
There are hundreds of different types of metamorphic rock. Some of these include Slate, Gneiss, Schist, Granulite, and many more.
The author is Joey Lewitin, an innovative designer in stone whose coaster website http://coasters.pebblez.com shows off some of his products and coasters
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