Guided Notes about Metamorphic Rocks

1. Guided Notes about Metamorphic Rocks Chapter 6, Section 3

2. 1) Describe how and when a metamorphic rock may form. • When high temperature and pressure combine to alter the texture, mineralogy, or chemical composition of a rock without melting it, a metamorphic rock may form.

3. 2) Where does the heat for metamorphism come from? • The heat for metamorphism comes from the Earth’s internal heat, generated in the core, and spread through the mantle.

4. 3) Where does the pressure come from? • Pressure for metamorphism comes from vertical pressure caused by the weight of overlying rock, or from the compressive forces of mountain building.

5. 4) What are the major differences between regional and contact metamorphism • When high temperature and pressure affect large regions of Earth’s crust, they produce large belts of regional metamorphism. • When molten rocks, such as those in an igneous intrusion, come in contact with solid rock, they form a local effect called contact metamorphism.

6. 5) What are the 2 classes of metamorphic rock texture? • Foliated • Nonfoliated

7. 6) What causes foliated rocks to form? • High pressure during metamorphism causes minerals with flat or needle-like crystals to form with their long axes perpendicular to the pressure.

8. 7) What are nonfoliated rocks made from? • They are made from minerals that form with blocky crystal shapes.

9. 8) How do porphyroblasts form, and what is one mineral… • When new metamorphic minerals grow very large crystals while the surrounding minerals remain small. • Garnets are an example of porphyroblasts.

10. 9) What is the rock cycle? How is it a type of recycling? • The continuous changing and remaking of rocks caused by the internal heat and pressure of the Earth and the processes of erosion is called the rock cycle. • The rock cycle is a type of recycling because the rocks of the Earth’s crust are constantly being reformed into different classes of rock.