1. Rocks
Earth’s crust is made of rock.
Rocks are mixtures of minerals and sometimes other materials.

2. When studying a rock sample, geologists observe the rock’s:
Color
Texture
Chemical composition

3. Most rocks are made up of grains, particles of minerals, or other rocks.
Texture is the look that results from:
Size
Shape
Pattern of rock’s grains

4. Coarse-grained--
large/easy to see.
Fine-grained – small, even microscopic.

5. Grains in rock often form a pattern.

6. Flat layers (strata)

7. Wavy, swirling patterns

8. Rows of beads

9. Random or no pattern

10. Some rocks have NO grain, because they cooled too quickly when they formed.

11. There are 3 groups of rocks:
Igneous
Metamorphic
Sedimentary

12. Igneous Rocks Formed from the cooling of molten (melted) rock.
Examples:
pumice, granite, basalt

13. Sedimentary Rocks
Formed when particles of other rocks, plants, or animals are cemented together.
Examples:
Sandstone, breccia, siltstone

14. Metamorphic Rocks
Formed when existing rock is changed by heat, pressure, or chemical reactions.
Examples:
gneiss, schist, phyllite

15. The Rock Cycle