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Presentation on theme: "Rocks."— Presentation transcript:

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

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.

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