12. Figure out foliation! Try this experiment to figure out how minerals become oriented when a rock is under pressure. <ul><li>Add mica flakes to a piece of play dough. The dough will represent a rock undergoing metamorphism. </li></ul><ul><li>Knead the dough until the mica flakes are well-incorporated roll your dough into a ball. </li></ul><ul><li>Break the ball of dough in half. The flakes will be oriented in all different directions just as they would be in an unmetamorphised rock. </li></ul><ul><li>Take one half of the ball and flatten it with the palm of your hand. The pressure that you are applying to the dough is like the pressure placed on our rocky Earth by the forces of plate tectonics. </li></ul><ul><li>Break the flattened dough in half and look at what has happened to the mica flakes! </li></ul>
15. It’s gneiss not to be taken for granite anymore!
16. sandstone quartzite
17. <ul><li>The weakly cemented quartz particles in the sandstone recrystallize to form quartzite. </li></ul>
19. limestone marble
20. Video Clip-Metamorphic Rock
21. Uses of metamorphic rocks:
22. <ul><li>marble - used to build buildings & statues </li></ul>
23. <ul><li>fine, even grain </li></ul><ul><li>can be cut into thin slabs or carved into many shapes </li></ul><ul><li>easy to polish </li></ul>
24. <ul><li>slate - </li></ul><ul><li>used for flooring, chalkboards </li></ul><ul><li>foliated- splits easily into flat surfaces </li></ul>
26. Let's Review
27. What does metamorphic mean?
28. The word "metamorphic" comes from Greek and means “to change form".
29. Where and under what conditions are metamorphic rocks formed?
30. Heat & pressure deep beneath Earth’s surface can change any rock into metamorphic rock.
31. What characteristic of metamorphic rocks do geologist use to classify them?
32. Geologists classify metamorphic rocks by the arrangement of their grains. 1. foliated 2. nonfoliated
33. How does a foliated metamorphic rock form?
34. A foliated metamorphic rock is formed when heat and pressure flatten the crystals in the rock.
35. Which of these rocks is foliated? How can you tell? Quartzite The grains in a foliated rock are arranged in parallel layers or bands.
36. foliated - walking single file
37. What is the main use of metamorphic rocks? <ul><li>The main use of metamorphic rocks is for building and sculpture. </li></ul>
38. Which might be more useful for carving chess pieces-marble or slate? Explain your answer. <ul><li>Marble would be more useful for carving chess pieces because marble can be carved into many shapes and be easily polished. </li></ul>
39. Activity-A Sequined Rock <ul><li>Make three balls of clay about 3 cm in diameter. Gently mix about 25 sequins into one ball. </li></ul><ul><li>Use a 30-cm piece of string to cut the ball in half. How are the sequins arranged? </li></ul><ul><li>Roll the clay with the sequins back into a ball. Stack the three balls with the sequin ball in the middle. Set these on a block of wood. With another block of wood, press slowly down until the stack is about 3 cm high. </li></ul><ul><li>Use the string to cut the stack in half. How are the sequins arranged? </li></ul><ul><li>Making Models What do the sequins in your model rock represent? Is this rock foliated or nonfoliated? </li></ul>