1. Classifying Rocks

2. What is a rock?
Rocks are naturally occurring solid mixtures of one or more minerals or organic matter.

3. Rocks A. Classifying Rocks
1. Composition – Minerals they are made from
A. Some rocks contain only one mineral
B. Most rocks contain more than one mineral
i. 20 minerals form most of the rocks that make up the earth’s crust

4. Texture 2. Texture- look and feel of a rocks surface
Grain – particles made of minerals or other rocks
A. Grain Size
1. Fine Grain – small grain
2. Coarse Grain – large grains
3. no visible grains
B. Grain Shape
1. Rounded Grain
2. Jagged Grain
C. Grain Pattern
1. Banded grain
2. Non-banded grain

5. Types A. Igneous Rocks- cooling of magma or lava
B. Sedimentary Rocks – particles of other rock or remains of plants and animals are pressed and cemented together
C. Metamorphic Rocks- existing rocks are changed by heat, pressure or chemical reactions

6. Igneous Rocks

7. Igneous Rocks A. types by Texture- size of grains or crystals
1. Extrusive Rock- magma or lava that cools and hardens at or near the earth’s surface
a. rock cools very quickly
b. crystals are small, if any at all
c. Examples: basalt, obsidian, pumice, rhyolite

8. Igneous Rocks
2. Intrusive Rock- magma that cools and hardens within the earth
a. rock cools very slow
b. crystals are very large
c. examples: granite, gabbro, diorite

9. Igneous Rocks Types by composition- amount of silica
1. high silica content – light colored
a. Examples: Granite, rhyolite
2. low silica content – dark colored
a. Examples: gabbro, basalt

10. Igneous rocks Uses of Igneous Rocks
1. Granite- statutes, headstones, bridges, buildings, floors, kitchen counters
2. Pumice, abrasives for cleaning and polishing
3. Obsidian- ancient tools

11. Igneous Video

12. Sedimentary Rocks

13. Sedimentary Rocks A. Process to form a sedimentary rock
1. weathering and erosion
weathering- wind and water breaking rocks into smaller pieces
Erosion- wind and water carrying away particles

14. Sedimentary Rocks
2. Deposition- sediments settling out of the wind or water

15. Sedimentary Rocks
3. Compaction- process of pressing the sediments together

16. Sedimentary Rocks
4. Cementation- dissolved minerals crystalize and glue particles of sediment together

17. Types of Sedimentary Rocks
1. Clastic Rocks-rocks made from pieces of other rock
a. shale – made of clay
b. sandstone – made from sand
c. conglomerate – mixture of different sized rounded particles
d. breccia- mixture of different sized jagged particles

18. Types of sedimentary rocks
2. Organic Rocks – made from the remains of plants and animals
a. coal – made from plants
b. limestone – made from coral, clams and oyster shells

19. Types of Sedimentary rocks
3. Chemical rocks – rocks made when minerals in a solution crystalize
a. limestone – made from calcite dissolved in lakes, seas or underground water
b. rock salt – made from evaporated oceans and seas

20. USES of sedimentary rocks
Sandstone – buildings
Limestone – buildings
Flint - Arrowheads

21. Process in which material is laid down
Process of Deposition
Process in which material is laid down

22. Weathering, Erosion and Deposition
All geological processes that make and destroy rock

23. Strata
Strata = Layers
Stratification- process in which sedimentary rocks are arranged in layers

24. Sedimentary rocks are the only rocks with fossils
Organic materials…
Sedimentary rocks are the only rocks with fossils

25. Metamorphic Rocks

26. Metamorphic Rocks
Metamorphic Rocks- existing rocks are changed by heat and pressure
Meta- change
Morphism - forms

27. Types of Metamorphic rocks
Foliated Rocks- when minerals flatten out and line up in bands or parallel layers due to pressure
a. gneiss forms from granite
b. slate forms from shale

28. Types of Metamorphic Rocks
2. Nonfoliated Rocks- rocks that do not show bands
Not enough pressure on the rock to form bands
a. marble forms from limestone
b. quartzite forms from sandstone

29. USES of metamorphic rocks
1. Marble: buildings, statues, countertop
2. Slate: flooring, roofing, chalkboards, pool tables

30. Metamorphic video