1. Rocks
ROCKS
Chapter 3

2. Rocks
Naturally occurring solid material made of one or more minerals
Grouped into 3 main types, based on the way it was formed

3. IGNEOUS
ROCKS #1

4. Formed from magma that cools and hardens “Fire Formed”
IGNEOUS ROCKS
Formed from magma that cools and hardens
“Fire Formed”

5. IGNEOUS ROCKS: 2 types Intrusive rocks: Cools slowly, large crystals
formed deep within Earth
Cools slowly, large crystals
Coarse grained
Extrusive rocks:
formed from lava at Earth’s surface
Cools quickly, small crystals
fine grained

6. IGNEOUS ROCKS: texture
Size of crystal grains and chemical composition are used to classify igneous rocks
Texture depends on time it takes a rock to harden (cooling rate)

7. IGNEOUS ROCKS: porphyry (POR-fuh-ree)
Igneous rock with a mixture of large and small crystals

8. Two types of magma
Felsic:
Light-colored
Thick and slow flowing
Rich in silica
Mafic:
Dark-colored
Very fluid
Rich in iron

15. Scoria

16. Igneous Rock Structures
Intrusions –underground rock masses
Extrusions – surface rock masses

17. Batholiths INTRUSIONS largest igneous intrusions
Form when huge bodies of magma cool underground
Cover 1000 km

18. Batholith

20. INTRUSIONS
Laccoliths
Domelike masses formed from magma bulging upward

22. This laccolith in Red and White Mountain, Colorado, is of
Tertiary age. Overlying layers of rock have been eroded.

23. INTRUSIONS
Dike
Sheets of igneous rocks that cut across the rock layer

25. Dike

26. Dike

27. INTRUSIONS
Sill
Sheet of hardened magma that forms between and parallel to layers of rock

29. Sill

30. Volcanic neck: EXTRUSIONS
The plug of hardened magma left in the vent from which lava flowed

32. Volcanic neck:

33. INTRUSIONS
Stock
Similar to batholiths but less than 100 km

37. SEDIMENTARY
ROCKS #2

38. 75% of Earth’s surface is sedimentary rock!
Sedimentary Rocks
75% of Earth’s surface is sedimentary rock!

39. How Sedimentary Rocks are made:
Mud, sand, gravel and shells are sediments that make up rocks
Sediments are moved by wind and water
Compaction: Pressure placed in sediment layers cause them to change to rocks
Cementation: sediments are joined together (cemented) by minerals dissolved in water
This process results in the formation of layers called strata.

41. The major characteristics of all sedimentary rocks is that they form layers!

42. ...We both have layers." Ogres are like sedimentary rocks!
"For your information, there's a lot more to ogres than people think...
Ogres are like sedimentary rocks!
…Sedimentary rocks have layers...
Ogres have layers!
...We both have layers."

43. Sedimentary rocks usually form in water
Ripple marks and mud cracks

44. Fossils often preserved in sedimentary rocks

45. Sedimentary Rocks: Classified by
Composition
Texture
Grain size

46. Types:
Clastic
Organic
Chemical

47. Formed by broken pieces or fragments of rock
1. Clastic Rocks
Formed by broken pieces or fragments of rock
Classified according to size and shape of fragments

48. Clastic Rocks Conglomerates:
Made of rounded pebbles and other rocks of different sizes and cemented together by clay, mud ,or sand
Formed when rivers deposit large pieces of rock
Pieces of rock rounded by water before deposited

49. Conglomerate:

50. Clastic Rocks
Breccia:
Similar to conglomerates, but fragments are sharp and angular
Not carried far enough by water to round the edges

51. Breccia:

52. Clastic Rocks Sandstone: Made of small, sand-sized grains Very common
Resistant to wear and decay
Used to make buildings

53. Sandstone:

54. Formed from small particles of clay Example: shale
Clastic Rocks
Mudrock:
Formed from small particles of clay
Example: shale

55. shale

56. shale

57. Formed directly or indirectly from material that used to be living
2. Organic Rock
Formed directly or indirectly from material that used to be living

58. Fossilized Limestone:
Organic Rock
Fossilized Limestone:
Shells from dead animals (containing calcium carbonate) that sink to bottom of ocean floor

59. Limestone:

60. Organic Rock
Chalk:
Composed of animals and calcium carbonate that have been pressed together

61. Chalk

62. Organic Rock
Coal:
Rock formed from plants that lived millions of years ago

63. 3. Chemical Rock
Formed by chemical means that do not involve any living organisms
Can occur through evaporation or chemical action

64. Formed directly from ocean water instead of organisms
Chemical Rock
Limestone:
Formed directly from ocean water instead of organisms

65. Chemical Limestone:

66. Natural form of common table salt Ex: Halite
Chemical Rock
Rock salt:
Natural form of common table salt
Ex: Halite

68. Chemical Rock
Rock gypsum:

69. METAMORPHIC
ROCKS #3

70. Metamorphic Rocks Metamorphism:
Changing of one type of rock in to another due to -
Tremendous heat
Great pressure
Chemical reactions ( a change in composition of minerals)

71. Metamorphic Rocks Types of Metamorphism: Contact Metamorphism
Occurs when rocks are heated by contact with magma or lava
Covers a small area
Regional Metamorphism
Occurs when rocks are buried deep beneath Earth’s surface and changed by increase in temperature and pressure
Covers a large area

72. Types of Metamorphic Rock:
Foliated Texture:
Mineral crystals arranged in parallel layers or bands (flatten under pressure)
Slate 
Schist 
Gneiss
(from clay or shale)
(from granite, basalt, or slate)
(from granite)

73. Foliated Texture:
slate

74. Foliated Texture:
phyllite:

75. Foliated Texture:
gneiss:

76. Types of Metamorphic Rock:
2. Unfoliated Texture:
No bands of crystals
Don’t break in layers

77. Unfoliated Texture:
marble

78. Unfoliated Texture:
quartzite