Aim:Aim: What are metamorphic rocks?

I. Metamorphic RocksMetamorphic Rocks – rocks that have been exposed to great heat and pressure.

A. Dynamic Metamorphism(Regional Dynamic Metamorphism(Regional Metamorphism)Metamorphism)- large areas of rock are under great heat and pressure. Ex: mountain building.

B. How heat and pressure cause rocks to change.

1. Pressure squeezes grains closer together, creating a denser and less porous rock.

2. Heat and chemicals may rearrange particles (atoms). Minerals are reformed or new ones are formed. Ex: Quartzite Quartzite was once sandstone sandstone and MarbleMarble was once limestonelimestone.

C. Characteristics of Metamorphic Rocks1. FoliationFoliation – grains are in parallel layers. Ex: slate. Gneiss is the coarsest foliation of all metamorphic rocks.2. BandingBanding – bands of light colored minerals alternate with bands of dark colored minerals.

D. Thermal Metamorphism (contact metamorphism) – Igneous intrusions bake overlying rock . The changes are less drastic than regional metamorphism and foliation is not produced.

GRANITE

GNEISS

Banding

Metamorphic Rock Flash