Discuss the formation of metamorphic rocks, including foliation development

Metamorphic rocks form when a rock of any classification (igneous, meta, or sed) is subjected to heat and/or pressure, resulting in recrystallisation. Contact metamorphism occurs around a crustal intrusion due to increased temperature, producing baked and chilled margins (dyke/sill) or a metamorphic aureole (pluton). Dynamic metamorphism occurs at elevated pressures with little temperature change, such as in a fault zone. Regional metamorphism involves a change in both temperature and pressure, and is associated with large-scale tectonic processes such as orogenesis.The application of pressure may cause minerals in the rock to align, creating a foliation. This occurs in rocks containing platy minerals such as micas or chlorite. Foliations become more developed with increasing metamorphic grade:Slaty Cleavage > Phyllitic > Schistose Texture > Gneissose Banding