What is Metamorphism?
'''Metamorphism''', in geology, is the change of the [[structure]], [[texture]], or composition of [[Rock (geology)|rocks]]. (an aggregation of solid matter composed of one or more of the minerals forming the earth's crust). The scientific study of rocks is called [[petrology]]. Rocks are commonly divided, according to their origin, into three major classes—[[Igneous Rock|Igneous]], [[Sedimentary rock|sedimentary]], and [[Metamorphic Rock|metamorphic]]. They are caused by the effects of [[heat]], deforming [[pressure]], [[shearing stress]], hot/chemically active [[Fluid|fluids]], or a combination of these. All of these changes occur while the rock remains essentially in the solid state. In theory, rocks are formed when the things surrounding them are in equilibrium with ambient physical conditions. If the conditions are changed by movements in the [[earth's crust]] or by [[Volcanism|igneous activity]], metamorphism occurs to reestablish equilibrium and changes the physical character of the rock mass. [[Category:Geology]]