1. Metamorphic Rocks

2. Metamorphic Rocks METAMORPHISISM
We know that increasing temperature and pressure during burial causes recrystallization and cementation of minerals and sediments.
What happens when rocks are buried at even greater depths?
Answer:
METAMORPHISISM

3. Metamorphic Rocks 1. Formation of Metamorphic Rocks
 Metamorphism means “to change form or shape.”
 Most metamorphic changes occur at high temperatures and pressures.
 Rocks change form while remaining semi-solid.

4. Cooking Rocks

5. Formation of Metamorphic Rocks
2 ways metamorphic rocks can form:
Formation of Metamorphic Rocks
Regional metamorphism results in large-scale deformation and high-grade metamorphism.
Directed pressures and high temperatures occur during mountain building.
Produces the greatest volume of metamorphic rock.

6. Regional Metamorphism

7. Cooking Rocks

8. Formation of Metamorphic Rocks
Contact metamorphism occurs when magma moves into existing rock.
Occurs near a body of magma (igneous intrusion).
Changes are driven by a rise in temperature.

9. Contact Metamorphism

10. 2 types of Metamorphic Textures
Metamorphic Texture: Foliated
2 types of Metamorphic Textures
Foliated - Wavy layers and bands of colors or minerals.
Foliated rocks require high pressure to align minerals.
Example: Gneiss

11. Foliation animation

12. Metamorphic Textures Metamorphic Texture: Non-foliated
Non-foliated - lack bands, usually are blocky crystalline masses.
Example: Quartzite
Secretary of War Jefferson Davis (later President of the Confederacy) had a novel idea: transporting freight and people across the desert Southwest on camels. He eventually imported over 70 of the beasts. Along with the first batch came a Syrian caretaker, Hadji Ali. His American masters called him Hi Jolly.
A plaque on Hi Jolly's tomb says of the camel experiment: "A fair trial might have resulted in complete success." But the Civil War intervened, Jefferson Davis changed jobs, and without his support the project was abandoned. The camels were set free to fend for themselves in the desert near Quartzsite.

13. Guess the metamorphic Textures

15. How to Identify Metamorphic Rocks
Step 1: Determine the texture – foliated or non-foliated.
Step 2: Determine if rock is coarse, medium, or fine-grained.

16. How to Identify Metamorphic Rocks
Step 3: Decide what kind of rock or sediment it used to be (composition). We call this the parent rock.
Step 4: Examine the sample for other properties such as minerals present, luster, color, hardness, fused mineral grains. Step 5: Name the sample.

18. Let’s look at some Metamorphic Rocks!
Go to lab and look at 6 metamorphic rock samples.
Sketch & color the rock.
Identify grain size, foliation, and features.
Try to name the rock.
We will review samples at the end of lab.