1. Chapter 3
TYPES OF:
Rocks

2. Rocks
Rocks
 Rocks are any solid mass of mineral or mineral-like matter occurring naturally as a part of our planet.
 Types of Rocks
The 3 kinds of rocks are igneous, sedimentary, and metamorphic

3. Igneous Rocks formed by the crystallization of molten magma or lava.
Magma is molten material deep beneath the Earth’s surface
Lava is molten material above the surface

4. Types of Igneous Rocks
1. Intrusive igneous rocks are formed when magma hardens beneath Earth’s surface.
2. Extrusive igneous rocks are formed when lava hardens (above the Earth’s surface).

5. How Igneous Rocks are Classified
 Igneous rocks can be classified based on their composition and texture.
1. Texture
• Coarse-grained texture is caused by slow cooling resulting in larger crystals.
• Fine-grained texture is caused by rapid cooling resulting in smaller, interconnected mineral grains.
• Glassy texture is caused by very rapid cooling.

6. Course-Grained Igneous Texture
Granite

7. Fine-Grained Igneous Texture
Rhyolite

8. Obsidian Exhibits a Glassy Texture.

9. 2. Composition
What the rock is made of, based on the amounts of light and dark minerals in the rock.

10. Porphyritic Igneous Texture

11. Basalt

12. Classification of Igneous Rocks

13. Sedimentary Rocks Formation of Sedimentary Rocks
• Erosion involves the weathering and the removal of rock.
• Deposition occurs when an agent of erosion—water, wind, ice, or gravity—loses energy and drops sediments.

14. Sedimentary Rock Formation

15. • Compaction is a process that squeezes, or compacts, sediments.
• Cementation takes place when dissolved minerals are deposited in the tiny spaces among the sediments.

16. 3 Types of Sedimentary Rock
Clastic – composed of weathered bits of rocks and minerals
Classified by particle size
Ex: Shale, Sandstone, Conglomerate, Grand canyon & the wave in Arizona

17. Shale with Plant Fossils

18. Sandstone

19. Conglomerate

20. The Wave, Page, AZ

21. Grand Canyon, Arizona

23. Chemical – When minerals dissolve out of water
Ex: limestone (caves), coal, rock salt

24. Fossiliferous Limestone

25. Carlsbad Caverns, NM
Stalactites
Stalagmites

26. Organic – Formed by fossils or organic matter within the rock layers

27. Classification of Sedimentary Rocks

28. Metamorphic Rocks Formation of Metamorphic Rocks
 Metamorphism means “to change form.”
 Igneous and sedimentary rocks change at elevated temperatures and pressures deep within the Earth or during mountain building

29. Agents of Metamorphism
 Heat
Provides the energy needed to drive chemical reactions
 Pressure
Causes a more compact rock with greater density

30. Origin of Pressure in Metamorphism

31.  Hydrothermal Solutions
Hot water-based solutions escaping from magma
Dissolves original minerals and then deposits new ones

32. Classifying Metamorphic Rocks
 Two main categories
1. Foliated Metamorphic Rock
Has a banded or layered appearance
2. Nonfoliated Metamorphic Rock
Does not have a banded texture

33. Classification of Metamorphic Rocks

34. Gneiss Typically Displays a Banded Appearance

35. Marble—A Nonfoliated Metamorphic Rock

36. Fill in the following table using your textbook (pgs. 71-84)
IGNEOUS ROCKS
SEDIMENTARY ROCKS
METAMORPHIC ROCKS