1. Herricks High School Earth Science
Metamorphic Rocks
Herricks High School
Earth Science

2. Metamorphism
The changes that occur in solid rock due to great temperature, great pressure, and chemical activity.

3. Three Factors of Change
Heat
Pressure
Chemical Activity

4. Metamorphism
Parent Rock- the preexisting rock from which a metamorphic rock forms
Parent Rock  Metamorphic

5. Types of Metamorphism
Regional Metamorphism: occurs over large areas and is associated with mountain building
Deeply buried igneous and sedimentary rocks are squeezed by the weight of rock layers above
Examples: Slate, Phyllite, Schist, Gneiss

6. Regional Metamorphism

7. Contact Metamorphism
Contact Metamorphism: occurs when molten rock comes into contact with surrounding rocks

8. How do metamorphic rocks change?
1. Crystalline Texture: Recrystallization
Under heat and pressure the size, shape, and spacing of grains change.
Rock may partially melt and fuse together forming larger crystals or pressure may break grains into smaller pieces, destroying the original texture of the rock

9. How do metamorphic rocks change? (con’t)
2. Increased Density:
Pressure from deep burial closes pore spaces in sedimentary rocks and openings in igneous
Its mass is forced into a smaller volume, and its density increases.

10. Visual Characteristics of Metamorphic Rocks
Foliation: results when mineral grains recrystallize or are flattened under pressure
A rock is said to be foliated when its crystals are arranged in layers or bands along which the rock breaks easily.
Example: foliation of gneiss

11. Visual Characteristics (con’t)
Banding: occurs when minerals of different densities recrystallize under pressure and separate into layers
Like oil and water
Alternate light and dark (light being less dense than dark)

12. Banding
gneiss

13. Visual Characteristics (con’t)
Distortion of Layers: When layers of rock become metamorphosed, twisting and contorting could occur.
These distortions are commonly seen in large-scale outcrops.

14. Distortion

16. Roman Forum, Roma, Italy 7/29/2011
Name That Rock!
Location:
Roman Forum, Roma, Italy 7/29/2011

17. Erosion Transportation Heat, pressure, stress Magma (molten rock)
Weathering
Deposition
Igneous rock Granite, pumice, basalt
Sedimentary rock Sandstone, limestone
Heat, pressure
Cooling
Heat, pressure, stress
Magma (molten rock)
Figure 15.8
Natural capital: the rock cycle is the slowest of the earth’s cyclic processes. The earth’s materials are recycled over millions of years by three processes: melting, erosion, and metamorphism, which produce igneous, sedimentary, and metamorphic rocks. Rock from any of these classes can be converted to rock of either of the other two classes, or can be recycled within its own class. QUESTION: List three ways that the rock cycle benefits your lifestyle.
Melting
Metamorphic rock Slate, marble, gneiss, quartzite
Fig. 15-8, p. 343 17

18. The Rock Cycle:
The Story of “Herbie”