BIG Idea ► Most rocks are formed from pre-existing rocks through external and internal geologic processes.
METAMORPHISM: ► The changing of one type of rock to another by heat, pressure and chemical processes. ► Rocks RECRYSTALLIZE - undergo change WITHOUT true melting
IMPORTANT Metamorphic Facts: ► New larger, DENSER, harder crystalline structures form ► Generally NON-porous (no holes) ► No fossils (destroyed due to intense heat and pressure)
TYPES OF METAMORPHISM 1. CONTACT METAMORPHISM – CHANGE TO A SMALL AREA – heat from magma alters the rock in contact with it.
2. REGIONAL METAMORPHISM – CHANGE TO A VERY LARGE AREA (mountain building) – tectonic activity.
CLASSIFICATION OF METAMORPHIC ROCKS ► 1. FOLIATED – PARALLEL BANDS OF MINERALS
► What is slate commonly used for?
► 2. NON-FOLIATED - ROCKS WITH NO BANDS OF CRYSTALS.
PARENT MATERIALS: Rock from which metamorphic rocks form Different rocks form with changes in heat and pressure
METAMORPHIC PARENTS: ► sandstone + heat and pressure = quartzite ► shale + heat and pressure = schist ► shale + heat and pressure = slate ► granite + heat and pressure = gneiss (“nice”) ► limestone + heat and pressure = marble