Metamorphic rock Metamorphic rock Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". The original rock (protolith) is subjected to heat (temperatures greater than 150 to 200 °C) and pressure ( or more), causing profound physical or chemical change. The protolith may be a sedimentary, igneous, or existing metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's land surface. They are classified by texture and by chemical and mineral assemblage (metamorphic facies). They may be formed simply by being deep beneath
History of heat Joule on the dynamical theory of heat, that: On this view, he argued that we must ""perceive that there must be an equivalence between mechanical work and heat, as between cause and effect."” Heat in modern terms, is generally defined as a type of energy transferred due to a temperature difference or that generated by friction. History of heat The history of heat has a prominent place in the history of science. It traces its origins to the first hominids to make fire and to speculate on its operation and meaning to modern day physicists who study the microscopic nature