1. ROCKS NJCCCS: 5.4 C – Properties of Earth Materials
Chapter 3
ROCKS
NJCCCS: 5.4 C – Properties of Earth Materials

2. What is a Rock?
A mixture of minerals, mineraloids, glass, or organic matter
ex. Granite = mica + quartz + feldspar + hornblende + other minerals

3. 3 Rock Types Igneous Rocks – form from cooling magma or lava
Metamorphic Rocks – form from extreme heat and pressure
Sedimentary Rocks – form from the compaction and cementation of sediment (rock fragments)

4. Other Key Terms Magma: molten rock inside the Earth
Lava: molten rock on the surface of the Earth
Sediment: smaller pieces of rock (rock fragments)
Weathering: breaking rocks into sediment
Erosion: moving sediment from one location to another
Compaction and Cementation: process of squeezing and gluing sediment into a sedimentary rock

5. The Rock Cycle

6. Igneous Rocks
Igneous Rocks - cooled molten material form the inside the Earth(magma) or out of a volcano (lava)
- the most common rock on Earth

7. Igneous Rocks
B. The Earth’s crust generates great temps (1400), pressures, and radioactive thermal energy
C. Rocks and Minerals melt to form magma, minerals have different densities and melting pts

8. Igneous Rocks
D. Magma is less dense than the crust above and forces an escape through volcanoes as lava
E. Sometimes magma forces upwards but cools before reaching the surface

9. Classification of Igneous Rocks (1)
Intrusive Igneous Rocks - those rocks that were formed from cooling magma below the Earth’s surface
Cool very slowly
Have large crystals called mineral grains
Extrusive Igneous Rocks - Rocks that formed from cooling lava on the surface of the Earth
-Cool very quickly
- Have very fine grained texture

10. IGNEOUS ROCKS – cooled magma or lava
Intrusive igneous rocks have large mineral grains!!!!!
Extrusive igneous rocks have virtually no mineral grains.

11. Classification of Igneous Rocks (2)
1. Basaltic – dense, heavy, dark colored rock, rich in magnesium and iron, most common
2. Granitic – light color, less dense, rich in silicon and oxygen
3. Andesitic – mineral compositions in between the two, common among Pacific Volcanoes

12. ANDESITE
BASALT
GRANITE

13. Igneous Features

14. (Plutonic) Intrusive Igneous Features
Magma Chamber is a large underground pool of molten rock found beneath the surface of the Earth.

15. Intrusive Igneous Features
Sill is an intrusion of magma that solidifies into a horizontal layer of igneous rock

16. Intrusive Igneous Features
Dike is a magma that cuts across rock layers (vertical)

17. Intrusive Igneous Features
Batholith is a magma chamber that cools before reaching the surface to form a volcano

18. Intrusive Igneous Features
Laccolith is a small magma chamber at shallow depth (roughly lens shaped)

19. Extrusive Igneous Features
Volcano is an opening, or rupture, in a planet's surface or crust, which allows hot magma, volcanic ash and gases to escape from below the surface
3 types:
Shield
Composite
Cinder

20. Extrusive Igneous Features
Lava Flow – different types of lava depending on the composition and temperature

21. Extrusive Igneous Features
Ash and Dust Particles

22. Extrusive Igneous Features
Pyroclastic Flow is a fast-moving current of extremely hot gas ( 1,830 °F) and rock which travel away from a volcano at speeds generally as great as 450 mph.

23. Sedimentary Rocks 3 Types of Sedimentary Rocks
1) Clastic – made from rock fragments
2) Chemical – evaporation or precipitation from solution
3) Organic – contains fossils

24. Classification of Sedimentary Rocks
1) Clastic
Made from sediments

25. Chemical – evaporation/precipitation

26. Organic – contain fossils
Coquina
Fossil-rich limestone

27. Sedimentary Rocks

28. Formation of Sedimentary Rocks
Weathering and erosion makes sediment!!!!
Glaciers Wind
Gravity Water

29. Sediment Sorting Clastic Sedimentary Rocks are made of rock fragments.
Parent Rock – source of rock fragments

30. Sediment Sorting - As erosional forces lose energy, sediment is deposited largest first-smallest last

31. Sediment Sorting Largest to Smallest Boulder Cobble Gravel Pebble Sand
Silt
Clay

32. Conglomerate
Pebbles  Conglomerate

33. Sandstone
Sand  Sandstone

34. Siltstone
Silt  Siltstone

35. Shale
Clay  Shale

36. Sediment Sorting

37. Organic Sedimentary Rock
Coal – formed from the
Remains of plants at the
Bottom of a body of water
Limestone – formed from the mixed skeletal remains of marine organisms

38. Chemical Sedimentary Rock
Gypsum – easily dissolves in water… gypsum rock forms when the water evaporates and crystallizes
Halite – (salt) – easily dissolves in water…halite forms when salt water evaporates and crystallizes

39. Metamorphic Rocks

40. Metamorphic Rocks
Metamorphic Rocks - rocks that have changed due to increases in temperature and pressure (the minerals inside them change shape and alignment)
- igneous, sedimentary, metamorphic rocks can metamorph
B. Ex. Basalt  Schist  Gneiss
Shale  Slate  Phyllite  Gneiss
Granite  Gneiss

41. Occurs in 2 general ways: 1) Contact Metamorphism
Metamorphic Rocks
Occurs in 2 general ways:
1) Contact Metamorphism
2) Regional Metamorphism

42. Contact Metamorphism
As magma pushes through rock layers beneath the Earth…nearby rock change slightly in composition and structure

43. Regional Metamorphism
As the Earth’s plates move, the same extreme pressures that build mountains also cause rocks to deform and change in composition

44. WHAT HAPPENS? Heat - (2 sources- magma and depth)
Minerals within the rock melt and re-crystalize thus changing the composition of the rock

45. WHAT HAPPENS?
Pressure – causes space between minerals to close – compacted often causing minerals to recrystalize

46. 2 classifications
Foliated – banded (layers) of minerals at 90 degree angles to the pressure that caused the metamorphism
Non-Foliated – no bands or layers (usually composed of only one type of mineral)

47. Metamorphic Rocks – HEAT AND PRESSURE
FOLIATED = bands of mineral grains
NON-FOLIATED = no bands of mineral grains

48. Rock Classification Igneous Metamorphic Sedimentary
Intrusive Foliated Clastic
Extrusive Non-Foliated Chemical
Organic
Basaltic (Mafic)
Andesitic
Granitic (Felsic)

50. NJCCCS: 5.4B History of the Earth 5.4.12.B.1, 2, 3
FOSSILS
NJCCCS: 5.4B History of the Earth
B.1, 2, 3

51. Fossils
Fossil - any naturally preserved evidence of past life

52. Understanding Decomposition
When an organism dies specialist organisms called decomposers and detritivores begin consuming its remains.
Decomposers are usually bacteria and fungi (think sour milk and moldy bread)
Detritivores are animals like vultures, hyenas, insect larvae, and a host of others (think maggots in a garbage can)
Most often only the hard tissue of the organism is left behind… bones and teeth, shells, exoskeletons, etc.
See Video clip – Blue Planet

53. Fossils Are Rare
Fossils only form under very special environmental conditions!!!!!!!
Usually found in sedimentary rocks…why?
Exceptions: Volcanic ash

54. 3 ways in which fossils form
1) Mineral Replacement
2) Mostly Unchanged
3) Trace

55. Mineral Replacement
Underground water removes original material 1 atom at a time and replaces it with minerals.
An exact copy is created out of the minerals calcite CaCO3 or silica SiO2.
*Most Common way in which fossils form
3 basic types Petrification, Molds, Casts

56. 1) Petrification
the organism gets totally replaced with minerals

57. 2) Molds
dead creature is covered with sediments and decays away. The remaining cavity in the shape of the original creature is the fossil = impression

58. 3) Cast
Minerals from ground water seep into the mold, precipitate out of solution, and a stone shape is the fossil

59. Mostly Unchanged
Actual original parts of an organism are left behind by several methods.
1) Simple Burial
2) Frozen
3) Amber
4) Mummification
5) Acidic Peat Bogs
6) Tar
SPECIAL ENVIRONMENTAL CONDITIONS EXIST THAT PREVENT DECOMPOSITION!!!!

60. 1) Simple Burial
bones and teeth most often remain…share similar properties to minerals (calcium carbonate)

61. 2) Frozen
soft parts of mammoths have been found in frozen arctic tundra
Why do we put food in a freezer?
Slows down decomposition!!

62. 3) Amber
resin or ancient tree sap captured creatures (insects, frogs, etc.)

63. 4) Mummification
creatures desiccate (dry out) and soft parts remain – salt and or lye prevent decomposition

64. 5) Acidic Peat Bogs
creatures have been preserved in some wetlands that have environmental conditions that prevent decomposition (lack of oxygen, extreme pH)

65. 6) Tar
ancient oil seeping from underground trapped creatures. La Brea Tar Pits in California hold bones of mammoths, sabretooth tigers, camels, and more. Tar prevented decomposition.

66. Trace Fossil Evidence
Evidence of past life NOT including plant or animal remains

67. 1) Footprints
2) Burrows
3) Borings (holes)
4) Coprolites (fossil dung)

68. Fossil Lab - BE CAREFUL
Some things look like fossils but really aren’t…called rock features.
Ripple Marks Geodes Cross Bedding

69. Common fossils in your lab
Coprolites Belemite
(dung) (Squid)
Trilobite Stromatolite (colony of bacteria)
(arthropod)
Ammonite (cuddlefish)