1. Igneous Rocks

2. What is an igneous rock? Born from fire
Any rock that forms from magma or lava
Most contain mineral crystals

4. Characteristics of Igneous Rocks
Classified according to their…
Origin
Texture
Mineral composition

5. Origin
Extrusive Rock- formed from lava that erupted onto Earth’s surface (ex. Basalt)
Intrusive Rock- igneous rock that formed when magma hardened beneath Earth’s surface (ex. Granite)

6. Granite
Basalt

7. Texture
Fine-grained
Coarse-grained
Glassy
porphyritic

8. Fine-Grained
Rapid cooling lava
Small crystals
Extrusive rocks

9. Coarse-Grained
Slow cooling magma
Large crystals
Intrusive rocks

10. Porphyritic
Large crystals scattered on a background of much smaller crystals
Intrusive rocks cool in 2 stages- rate of cooling is changed from slow to fast

11. What is the texture of the rock?
Flow banding

12. Mineral Composition Lava that is low in silica- dark colored rocks
Magma high in silica- light colored rock

13. Uses of Igneous Rocks
Igneous rocks are hard, dense, and durable so they are used for
Tools
Building materials
Granite- long history of building material

14. Sedimentary Rocks

15. What is a sedimentary rock?
Composed of sediments derived from pre-existing rocks or by the crystallization of minerals that were held in solutions
Sediment- small, solid pieces of material that come from rocks or living things
Can include fossils, leaves, etc.

16. How do the sediments turn into a rock?
Erosion
Deposition
Compaction
Cementation

17. Erosion
Water, wind, or ice loosen and carry away fragments of rock

18. Deposition
That’s when sediments stop traveling by water or wind and settle

20. Compaction Sediments fit loosely Years go by…thick layers build up
Layers are heavy and press down
Compaction- process that presses sediments together (squeezes)

21. Cementation During compaction…minerals dissolve in water
Dissolved minerals crystallize and glue particles of sediments together
Whole process: millions of years

23. Types of Sedimentary Rocks
Clastic rocks
Organic rocks
Chemical rocks

24. Clastic Rocks Forms when rock fragments are squeezed together
Grouped by size of fragments & of which they are made
Ex. shale, sandstone, conglomerate and breccia

25. Shale
Forms from tiny particles of clay
Thin, flat layers

26. Sandstone
Forms from sand Contains holes- can absorb water

27. Conglomerate & Breccia
Mixture of rock fragments of different sizes

28. Organic Rocks Remains of plants & animals are deposited in layers
Coal and limestone

29. Coal
From remains of swampy plants

30. Limestone
From hard shells of living things
Ex. chalk

31. Chemical Rocks
Forms when minerals that are dissolved in a solution crystallize (ex. rock salt)

32. Metamorphic Rocks

33. What is a metamorphic rock?
A rock that has changed its form
Can change igneous, sedimentary, or other metamorphic rocks

34. How do metamorphic rocks form?
Heat and pressure beneath Earth’s surface change rock
Its appearance, texture, crystal structure, and mineral content change

35. Formation of Metamorphic Rocks
Earth’s plates push rock down toward mantle- HOT!
Magma also heats the rock
The deeper the rock is buried…the greater the pressure
Pressure and heat change minerals

36. Formation of Metamorphic Rocks

37. Granite to Gneiss GRANITE
Gneissic granite – separation of dark & light minerals is just beginning
Well banded gneiss

38. Classifying Metamorphic Rocks
Classify rocks by arrangement of grains that make up the rock
Two types: foliated and nonfoliated

39. Foliated Rock Grains arranged in parallel layers
Can split apart along the bands

40. Shale to Slate
Shale
Slate

41. Nonfoliated Rock Mineral grains are arranged randomly
Do not split into layers
Marble

42. Sandstone to Quartzite

43. Uses of Metamorphic rocks
Slate and marble- most useful metamorphic rocks
Marbles- buildings and statues
Slate- flooring, roofing, chalkboards