Metamorphic Rocks https://www.youtube.com/watch?v=2g-v-u5O3Xc http://www.youtube.com/watch?v=1oQ1J0w3x0o

Formation Deep within the Earth heat and pressure alter a parent rock without melting it “Recrystallization”

Regional Metamorphism Caused by extreme pressure and heat. Happens over wide “regions”. Mountain building, plate tectonic forces

Contact Metamorphism Molten rock, extremely hot, comes into contact with older surrounding rocks

Texture Refers to whether or not the component minerals are arranged in any irregular, repeated parallel pattern

a. Foliated Repeated layer-like appearance due to parallel alignment of flat or long grains i. Mineral alignment – parallel alignment of minerals ii. Banded – alternate between light and dark wavy stripes

Distorted Structure

Types of Foliation: Banded Gneissic Foliation- minerals are squished into bands – alternate light and dark wavy stripes “Zebra Stripes”

Banding vs. Layers Banding Layers – Sedimentary Rock ONLY

Schistose foliation- minerals have been squashed into flakes of mica.

A Piece of Schist

Holey Schist

Slaty foliation- Rock splits into flat, thin layers.

b. Non-foliated Composed of interconnected mineral crystals Distinguish by mineral content Quartzite Marble

HOW DO YOU KNOW IT’S A METAMORPHIC ROCK? it has: Foliation Banding

Take out your Handy Dandy Earth Science Reference Tables Page 7.

Regional Metamorphism If you add more heat and pressure to slate it will become phyllite. If you add more heat and pressure to phyllite, it will become schist. If you add more heat and pressure to schist, it will become gneiss. If you add more heat and pressure to gneiss then it will re-melt back to magma and become an igneous rock.

Slate + + = Phyllite

Phyllite + + = Schist

Schist + + = Gneiss

Rock Cycle Natural process in which rocks change from one rock type into another rock type over time

ESRT Page 6