J OURNAL #45 Describe the 3 major rock types Igneous Sedimentary Metamorphic Refer to notes and textbook as needed

T ODAY, WE WILL DESCRIBE THE PROCESS OF METAMORPHISM

F ORMATION OF M ETAMORPHIC R OCKS Metamorphic rock- forms from existing rock that has been altered by tremendous amount of pressure and extreme heat Any rock can become metamorphic rock. Metamorphism- the process by which heat, pressure or chemical processes change one type of rock to another. All metamorphic rock forms from existing igneous, sedimentary or metamorphic rock.

M ETAMORPHISM There are 2 types of metamorphism Contact Metamorphism When small volumes of rock come into contact with magma Regional Metamorphism When large areas of earth’s crust are affected by the heat and pressure that is caused by the movement and collisions of Earth’s giant tectonic plates.

C LASSIFICATION OF M ETAMORPHIC R OCK Metamorphic rocks are classified by chemical composition and texture. Metamorphic rocks have either a foliated texture or a nonfoliated texture. Foliated Rocks Foliation- the texture in which mineral grains are arranged in planes or bands

C LASSIFICATION OF M ETAMORPHIC R OCK Foliated Rocks Foliation- the texture in which mineral grains are arranged in planes or bands Foliated rock can form in one of ways: 1. Extreme pressure causes the mineral crystals in the rock to realign. 2. Different compositions separate to produce a series of alternating dark and light bands Examples: Schist, Gneiss

I S THIS ROCK FOLIATED METAMORPHIC ROCK OR NONFOLIATED ?

C LASSIFICATION OF M ETAMORPHIC R OCK Nonfoliated- rocks that do not have bands or aligned minerals. Rock may contain grains of only one material so bands do not occur Or the rock may contain grains that are round or square so they do not change position when exposed to pressure. Examples: Qaurtzite, marble

L ET ’ S R EVIEW What is metamorphism? What type of rocks can become metamorphic rocks? Name 2 ways that metamorphic rocks form.

I S THIS ROCK FOLIATED METAMORPHIC ROCK OR NONFOLIATED ?

Y OUR ASSIGNMENT : Complete Metamorphic Rock Review I have 5 rocks set up on the left side of the room on the lab bench. Determine if each rock is foliated or nonfoliated.