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
Alan (given name) Iranian "*aryāna", "noble people") because the long vowel in the second syllable would produce Old Breton "-o-", Middle Breton "-eu-" and Modern Breton "-e-" and not the attested spelling with an "-a-". In Ireland and Gaelic-speaking Scotland, Alan may also be an Anglicization of an Irish word (with diminutive suffix) meaning "rock". For example, the modern Irish "ailín" means "little rock". Similarly, according to Patrick Woulfe, the Irish name "Ailín" is derived from diminutive "ail", which means "noble", "rock". Woulfe stated that this name is a pet form of some other name beginning with the first element "Ail-". Forms of