1. 3.4 Metamorphic Rocks Metamorphism – “to change form” I. Formation of Metamorphic Rocks - Most changes occur at high temperatures and pressures a few km below the Earth’s surface. Gneiss Rock

2. A.Contact Metamorphism – hot magma moves into rock. B. Regional Metamorphism – results in large-scale deformation and high-grade metamorphism.

3. II. Agents of Metamorphism * A. Heat – The most important agent. Provides the energy needed to drive chemical reactions. - The heat comes from magma and the change in temperature with depth. *B. Pressure (Stress) – Causes a more compact rock with greater density

4. Origin of Pressure in Metamorphism

5. III. Classification of Metamorphic Rocks Can be classified by texture and composition. A.Foliated Metamorphic Rocks - rock has a layered or banded appearance. Ex: Gneiss & Schist.

6. Gneiss Typically Displays a Banded Appearance

7. B. Nonfoliated Metamorphic Rocks – - Does not have a banded texture. - Most only contain one mineral. Ex: Marble (calcite) parent rock = limestone & Quartzite Marble

8. Marble - A Nonfoliated Metamorphic Rock

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