|
|
|
|
|
Metamorphic rocks constitute one of the three standard groups into which rocks are separated. Their name is taken from the Greek for "transform," since all metamorphic rocks began their existence as earlier-formed igneous, sedimentary, or even metamorphic rocks.
Heat and pressure, generally deep below the Earth's surface, play vital roles in producing metamorphic rocks. During metamorphic minerals within a rock re-crystallize, taking new shapes and growing together to form new textural patterns. Some minerals become chemically unstable and react with neighbouring minerals of different chemical compositions. This produces fluids and vapours in the rock which forms new minerals.  This transformation make the rock chemically stable in it's habitat. The rocks develop distinctive structures, textures, and mineral assemblages that make them readily identifiable in the field.
Metamorphic rocks may be observed mainly in the uplifted roots of mountain belts, where deep burial has kept them under physical conditions sufficient to transform them. They are found in mountain ranges such as the Appalachians, Rockies, Sierra Nevadas, Pacific Coast Ranges, Andes, Alps, and Himalayas. In addition, they form many of the ancient rocks of the Canadian, Brazilian, African, Scandinavian, Australian, and East Antarctic continental shields. They also form the floor of the great sedimentary basins of all the continents.
Pictures: Above- The Grand Canyon
|
|
|
