Metamorphic Rocks 3.4

Metamorphism • The changes in mineral composition and

texture of a rock subjected to high temperature and pressure within Earth.

Contact Metamorphism • Changes in a rock caused by the heat

from a nearby magma body.

Regional Metamorphism

• Metamorphism associated with large-scale mountain-building processes.

Hydrothermal Solution • The hot, watery solution that escapes

from a mass of magma during the later stages of crystallization; such solutions may alter the surrounding rock.

Foliated Metamorphic Rock• A metamorphic rock with a texture that

gives the rock a layered appearance

Nonfoliated Metamorphic Rock• Metamorphic rock that does not exhibit

a banded or layered appearance.

Key Concept

• Where does most metamorphism take place?–Most metamorphic changes occur at

elevated temperatures and pressures. These conditions are found a few kilometers below Earth’s surface and extend into the upper mantle.

Key Concept

• How is contact metamorphism different from regional metamorphism?–Contact metamorphism hot magma

moves into rock and Regional metamorphism results in large-scale deformation and high-grade metamorphism.

Key Concept

• What are three agents of metamorphism, and what kinds of changes does each cause?–The agents of metamorphism are heat,

pressure, and hydrothermal solutions.

Key Concept

• How are metamorphic rocks classified?–They are classified by their texture.