1. Rocks

2. Different from minerals
Can be organic
Classified by:
Color
Texture
Mineral composition
Origin (how they were formed).
Three main groups of rocks.

3. Igneous Rocks Formed by cooled magma or lava.
Found in volcanic regions
2 types:
Intrusive: Rocks that cool under Earth’s surface.
Cool slowly.
Grains of rock are bigger
Extrusive: Rocks that cool on Earth’s surface.
Cool quickly.
Grains of rock are smaller, with more air spaces (pores)

4. Examples Intrusive rocks: Extrusive rocks: Granite Basalt - Obsidian
- Pumice

5. Sedimentary Rocks 5 step process creates sedimentary rocks Deposition:
Sediments are laid down in a new location. Build up in layers.
Weathering:
Existing rock is broken down into sediments.
Erosion:
Sediments are carried away to a new location
Cementation:
Sediments are glued together by a chemical reaction.
Compaction:
Sediments are pressed together by the wieght of new sediment on top.

6. Sedimentary Rocks cont.
Usually seen in layers.
Fossils are found only in sedimentary rocks.

7. Examples
Sandstone
Shale
Limestone
Conglomerate

8. Metamorphic Rocks
Formed by heat and pressure acting on existing rocks.
(heat & pressure)
Sandstone
Quartzite

9. Other Examples (heat & pressure) Shale Slate (heat & pressure) Granite
Gneiss

10. (heat & pressure)
Limestone
Marble

11. Metamorphic rocks cont.
2 types:
Foliated: The grains of the rocks are arranged in parallel layers or bands.
Nonfoliated: Grains are not arranged in parallel layers.