Metamorphic Rocks

Transforming Rocks•Rocks change because of

changes in temperature and pressure, or the presence of hot, watery fluids.

•Mineral grains of rocks are flattened and aligned when heat and pressure are applied.

Heat & Pressure•Temperature and Pressure increase as you travel deeper below the surface of the Earth.

•Heat and pressure sometimes cause rocks to melt = Igneous Rocks

• In other areas, melting doesn’t occur = Mineral grain of rocks become flattened.

• During this process, minerals exchange atoms with surrounding minerals to form bigger mineral deposits.

Example of Metamorphic Rock

Formation•Shale + Heat + Pressure = Slate

• Increasing Heat & Pressure:•Slate + Heat + Pressure = Phyllite•Phyllite + Heat + Pressure =Schist•Schist + Heat + Pressure = Gneiss

Hot Fluids•Fluids can move through solid

rock.

•These fluids are mostly water with dissolved elements.

•These fluids react chemically with the rock to change its composition without having to melt it.

Classifying Metamorphic Rocks

•Classify metamorphic rocks according to their composition and texture.

•2 Categories –Foliated and Nonfoliated.

Foliated Rock•Mineral grains line up in parallel

layers.

•Foliation = Bands•Can easily separate along foliation

layers (Roof and tiling).

•Ex: Slate and Gneiss.http://seis.natsci.csulb.edu/bperry/shaleslateB2.JPGhttp://upload.wikimedia.org/wikipedia/commons/6/60/Gneiss.jpg

Nonfoliated Rock• Minerals grains grow and

rearrange, but DO NOT form layers.

• Ex: Sandstone + Pressure = Quartzite

• Limestone + Heat + Pressure =Marble