1. Igneous Rocks that are formed from melted rocks Magma or lava cools
There are two types of igneous rock

2. Intrusive- Igneous rocks that cooled and formed underground.
2 Types of Igneous Rocks
Extrusive- Igneous rocks that cooled and formed above ground.
Intrusive- Igneous rocks that cooled and formed underground.

3. Intrusive Igneous Rocks
Cool slowly, underground.
Slow cooling = LARGE crystals
Crystals are visible to eye
Example: Granite, Diorite

4. Extrusive Igneous Rocks
Lava cools quickly on surface.
Microscopic crystals= FAST cooling
Often looks like glass
Example: Obsidian

5. Extrusive
Lava often cools quickly, trapping air bubbles (vacuoles) in the rock.
These air bubbles make the rock feel very light.
Example: Pumice

6. Sedimentary
Rocks that are formed from pieces of rocks or organic matter.
Compacted and cemented together.

7. Types of Sedimentary
Clastic – sedimentary rocks from deposition of rock particles
Biochemical – sedimentary rocks from deposition of organic matter

8. Fossils
If the sample contains fossils, it must be sedimentary. Only sedimentary rocks have fossils.

9. Sometimes layered Grains can be large (coarse) or small (fine)
Cemented Grains
Sometimes layered
Grains can be large (coarse) or small (fine)

10. Examples Coquina - Small shells cemented together. Layered Sandstone
Conglomerate – meaning all different sizes
Shale or slate

11. Rocks that have been changed by heat and/or pressure.
Metamorphic
Rocks that have been changed by heat and/or pressure.

12. Common Metamorphic Rocks
Limestone becomes Marble
Shale and Slate become Schist
Sandstone becomes Quartzite
Granite becomes Gneiss

13. How do metamorphic rocks form?
The parent rock can be “cooked” by a nearby magma intrusion. Called contact metamorphism.
High pressure from rocks crashing together at convergent plate boundaries.

14. What clues do I look for?
Foliated – metamorphic rocks that are layered
Crystals squeeze flat and connect into a banding pattern

15. Nonfoliated – metamorphic rocks that are not layered
What clues do I look for?
Nonfoliated – metamorphic rocks that are not layered

16. The Rock Cycle

17. What you will learn… What are the 3 types of rocks?
How are each formed?
What clues do they give about their formation?
How can I use physical characteristics to identify them?

18. How is this a cycle ? The rocks are constantly being recycled.
Almost all of the Earth’s crust has been recycled (re-melted and began again as igneous rocks)