Describe the differences between regional and contact metamorphism.

Metamorphism is the the solid state change of minerals and textures within a pre existing rock (country rock) as a result of changing pressure/ temperature conditions. Fluids such as H2O also play a very important role. 

Regional metamorphism occurs as a result of convergent tectonic activity and is usually characterised by low temperature and high pressure conditions. Thus this type of metamorphism is often associated with orogenic events and causes metamorphism over a large area. Barrovian zone sequences and structures such as folds are formed under regional metamorphic conditions. 

Conversely, contact metamorphism usually occurs on a smaller scale under higher temperature conditions associated with igneous intrusions. As the magma intrudes into the country rock the high temperatures ‘bake’ the surrounding country rock and a metamorphic aureole is formed. The rocks formed are generally called hornfels.