5. BIG Idea ► Most rocks are formed from pre-existing rocks through external and internal geologic processes.

6. METAMORPHISM: ► The changing of one type of rock to another by heat, pressure and chemical processes. ► Rocks RECRYSTALLIZE - undergo change WITHOUT true melting

7. IMPORTANT Metamorphic Facts: ► New larger, DENSER, harder crystalline structures form ► Generally NON-porous (no holes) ► No fossils (destroyed due to intense heat and pressure)

8. TYPES OF METAMORPHISM 1. CONTACT METAMORPHISM – CHANGE TO A SMALL AREA – heat from magma alters the rock in contact with it.

10. 2. REGIONAL METAMORPHISM – CHANGE TO A VERY LARGE AREA (mountain building) – tectonic activity.

11. CLASSIFICATION OF METAMORPHIC ROCKS ► 1. FOLIATED – PARALLEL BANDS OF MINERALS

13. ► What is slate commonly used for?

16. ► 2. NON-FOLIATED - ROCKS WITH NO BANDS OF CRYSTALS.

19. PARENT MATERIALS:  Rock from which metamorphic rocks form  Different rocks form with changes in heat and pressure

20. 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