1. Chapter 4- Rocks
Earth Science
White lava rock

2. Bell Work Lesson 4.1 Rock- Natural, solid mixture of minerals/grains
Grain- What mineralogists call the fragments that make up a rock
Texture- The grain size and the way the grains fit together
Magma- Molten or liquid rock underground
Lava- Molten rock that erupts on Earth’s surface
Sediment- Rock material that forms where rocks are broken down into smaller pieces or dissolved in water as rocks erode
Rock cycle- The series of processes that change one type of rock into another type of rock

3. Rocks A natural, solid mixture of minerals or grains
Grain= fragments that make up rock
Mineral crystals, broken bits of minerals or rock fragments
Can contain remains of organisms or volcanic glass
Closeup of the sample above, showing discrete grains of olivine, pyroxene, opaques, and plagioclase.

4. How to classify rocks?
Two important observations:
Texture
Composition

5. Texture The grain size and the way the grains for together
Look at the size of the minerals or grains
Look at the arrangement of the minerals or grains
What is the overall feel of the rock?

6. Composition Classified by the minerals or grains present in a rock
Can tell a geologist where the rock formed
Certain minerals can suggest rock formed under extreme temperature or pressure

7. Three major rock types Based on how they form Three types:
Can determine where they formed based on the characteristics
Three types:
Igneous
Sedimentary
Metamorphic

8. Igneous rock
When magma or lava cools and crystallizes, it creates this kind of rock.
Magma= molten or liquid rock underground
Lava= molten rock that erupts on Earth’s surface
The crystals that grow form the grains of the rock
Can form in different environments:
Subduction zones, mid-ocean ridges, hot spots (lots of volcanoes)
A lithosphere (Ancient Greek: λίθος [lithos] for "rocky", and σφαῖρα [sphaira] for "sphere") is the rigid,[1] outermost shell of a rocky planet, and can be identified on the basis of its mechanical properties. On Earth, it comprises the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.

9. Igneous rock cont’d

10. Sedimentary rock
Sediment: rock material that forms where rocks are broken down into smaller pieces or dissolved in water as rocks erode
Sediment, mineral crystals, remains or plants and animals are building blocks of sedimentary rock

11. Sedimentary rock cont’d
Rock forms where sediment is deposited (added to a landform)
Examples of where sediment is deposited: Rivers/streams, deserts, valleys
Loose sediment will someday turn into rock
Examples of where sedimentary rocks can be found: mountain valleys, along river banks, beach etc.

12. Metamorphic rock
Rocks that are exposed to extreme temperature and pressure can change to metamorphic rock
Can happen along plate boundaries
Can also happen if rock is exposed to some chemical fluids
Minerals change AND texture changes when the rock changes into metamorphic rock.
Grains can look bent or twisted

13. Metamorphic rock cont’d
Can form from ANY rock (including other metamorphic rock)
Limestone (sedimentary rock) metamorphoses into marble
Granite (igneous rock) metamorphoses into gneiss.

14. Rock Cycle
The series of processes that change one type of rock into another type of rock
Rocks are changing all the time
Slowly
Because of forces within Earth and on Earth’s surface
Example: 1- Lava forms igneous rock; 2- the rock is exposed to Earth’s surface and is eroded by water to form sediment; 3- the sediment cements together to form sedimentary rock.

15. Rock cycle cont’d Some processes can only occur under Earth’s surface
Extreme pressure and temperature (and melting)
Some rocks that are made under Earth’s surface change when uplifted to Earth’s surface
What changes can happen once on surface?
Weathering, erosion, deposition, compaction, cementation.
Uplifted= techtonic process that forces these rocks onto Earth’s surface

16. HOMEWORK Ch4 L.1 Vocabulary words on flash cards Outline Lesson 1
MEMORIZE THEM FOR QUIZ
Outline Lesson 1
Lesson Review questions
P. 116 #1-8
QUIZ!!!!

17. LaunchLab p.111 Obtain a rock sample
Examine the rock with/without a magnifying glass
Describe rock in detail
Color
Texture
Anything weird/cool in it?
Any minerals/grains you can see?
WRITE YOUR NAME ON PAPER AND TURN IT IN

18. Ch4 L.2 Igneous Rocks

19. Bell Work Ch4 L.2
Extrusive rock: When volcanic material erupts and cools and crystallizes on Earth’s surface
Volcanic Glass: Rock that forms when lava cools too quickly to form crystals
Intrusive Rock: Igneous rocks that form as magma cools slowly underground

20. Essential questions: How do igneous rocks form?
What are the common types of igneous rocks?

21. Launch Lab p.119
Observe what happens when I drop hot, melted sugar into your beaker of water.
One time slowly
One time quickly
Record what happens
What is the difference between the two?
WRITE YOUR FULL NAMES ON IT AND TURN IT IN.
WORK IN PAIRS.

22. Igneous rock formation
Lava cools to become igneous rock
Happens quickly when exposed to air
Darker color where already started to crystallize
Magma cools slowly below Earth’s surface
Can become exposed to the Earth’s surface eventually after wind, water and other factors wear away the ground on top of it
pic

23. Extrusive rocks
When volcanic material erupts and cools and crystallizes on Earth’s surface
Lava and ash solidify to form this
Happens fast= not enough time for crystals to grow
Fine-grained texture

24. Extrusive rocks cont’d
Volcanic glass= rock that forms when lava cools too quickly to form crystals
Example: Obsidian (both pictures)

25. Extrusive rocks cont’d
Gases can be trapped in magma
Magma moves towards the surface
Gases can cause eruptions (think of carbonation in soda)
Gas-rich lava erupts and gases escape
Forms special igneous extrusive rocks
Example: pumice
Why do you think pumice has all those holes?
Pumice + scoria are cousins but scoria doesn’t float, it’s more dense than pumice

26. Mini Lab p.120 I NEED 3 VOLUNTEERS
Each Volunteer will receive 1 beaker and 1 watch glasse
Fill the three beakers with water
One filled with HOT water
One filled with WARM water
One filled with COLD water
Place the beakers in the back of the room
Place one watch glass on each of the beaker
MAKE SURE THERE IS ENOUGH WATER SO IT IS TOUCHING THE WATCH GLASS
I will come around and pour 3mL of water with dissolved Epsom salt. We will look at the crystals TOMORROW.

27. Intrusive rock
Igneous rocks that form as magma cools slowly underground
Large, well-defined crystals can form
Random arrangement of crystals
Crystals interlock like a jigsaw puzzle
Typical characteristics:
Large crystals
Random arrangement

28. Igneous rock identification
Texture:
Crystal size
Small + hard to see (sometimes only with magnifying lens)= extrusive
Large enough to see with interlocking arrangement= intrusive

29. Igneous rock identification
Composition:
Silica content (estimate based on color of minerals)
Darker colored minerals= usually less silica and more magnesium and iron
Examples: Perodite contains minerals olivine and pyroxene
Lighter colored minerals= usually more silica
Examples: rhyolite contains minerals quartz and feldspar

30. Igneous rock identification

31. Igneous rock identification

32. HOMEWORK Ch4 L.2 Vocabulary words on Flash Cards Outline Ch4 L.2
MEMORIZE FOR QUIZ
Outline Ch4 L.2
Lesson review questions
Page 123
Questions 1-10
QUIZ!!!!!

33. Ch4 L.3 Sedimentary Rocks

34. Bell Work Ch4 L.3
Compaction: the weight from layers of sediment forces out fluids and decreases space between grains
Cementation: Minerals dissolved in water crystallize between sediment grains
Clastic rock: Made up of broken pieces of minerals and rock fragments
Clast: the broken pieces of minerals and rock fragments that form clastic rock.
Chemical rock: form when minerals crystallize directly from water.
Biochemical rock: Sedimentary rock that was formed by organisms or contains the remains of organisms

35. Essential questions How do sedimentary rocks form?
What are the three types of sedimentary rocks?

36. Mini Lab Follow up What do you think crystals will look like?
Write down your predictions. THEN go to the back of the room and observe the crystals formed from the three environments
Hot, Warm, Cold
Record your observations
How are the crystals different?
Prediction (hot)
Prediction (warm)
Prediction (cold)
Observation (hot)
Observation (warm)
Observation (cold)

37. Sedimentary rock formation
Can form in different environments
Water and air can break down rock
Also can transport rock fragments to new locations
Sediment deposited in layers
Gets thicker over time
Compaction: the weight from layers of sediment forces out fluids and decreases space between grains

38. Sedimentary rock formation cont’d
Compaction can lead to cementation
Minerals dissolved in water crystallize between sediment grains
Holds grains together
Examples of minerals that cement: quartz, calcite, and clay

39. Sedimentary rock identification
Classified according to how they form
Deposited, compacted then cemented
Evaporation when minerals crystallize from water
When organisms remove minerals from water to make shells or skeletons

40. Clastic Sedimentary Rocks
Made up of broken pieces of minerals and rock fragments
Clasts= broken pieces
Identify according to clast shape and size
Can’t use shape alone
Can be as big as a car or as small as a grain of flour
Shape helps determine environment where it formed
Small, gritty sediment= typically in calm environments (sea floor, bottom of lake)
Large sediment= can be moved by oceans waves, fast flowing rivers

41. Chemical sedimentary rock
Dissolved minerals can be carried from rivers to the ocean (contribute to saltiness)
Water can be saturated with dissolved mineral and minerals can crystallize out of the water
Chemical rocks form when minerals crystallize directly from water.

42. Chemical sedimentary rock cont’d
Examples: rock salt (halite), rock gypsum, limestone
Interlocking crystalline texture (similar to igneous rocks)
Generally composed of one dominant mineral= uniform in color
Different from igneous rocks (generally many minerals)= multi-colored

43. Biochemical sedimentary rocks
Sedimentary rock that was formed by organisms or contains the remains of organisms
Most common= limestone
Organisms make shells from dissolved minerals
Organism dies and shells settle on the floor= forms part of rock
If contains fossils= fossiliferous

44. Biochemical sedimentary rocks
Carbonate rock= contains carbon and oxygen
Will fizz when add hydrochloric acid
Limestone is an example
Not all biochemical rocks are carbonates
Diatomite looks like limestone but doesn’t fizz with HCl
Coal
Composed of remains of plants and animals
Buried and compressed to eventually form sedimentary rock

45. Common Chemical and Biochemical Rocks

46. Mini Lab p. 128
Use grains of sedimentary rocks to identify the environment where they likely formed
What to look for? (Write this down for each)
Grain size
Grain shape
Have you seen something similar before?
Guess: in what environment was each formed?
Grain Size?
Grain Shape?
Seen this before?
Environment guess #1 #2 #3 #4

47. HOMEWORK Vocabulary words on Flash Cards Ch4 L.3 Outline
Memorize for quiz
Ch4 L.3 Outline
Lesson review questions
Page 130
Questions 1-10
QUIZ

48. Ch4 L.4 Metamorphic Rock

49. Bell Work Ch4 L.4
Metamorphism: any process that affects the structure or composition of a rock in a solid state as a result of changes in temperature, pressure or the addition of chemical fluids
Plastic deformation: permanent change in shape by bending and folding
Foliated rock: metamorphic rock that contains parallel layers of flat and elongated minerals
Contact metamorphism: Magma comes in contact with existing rock, its thermal energy and gases interact with the surrounding rock, forming new rock.
Regional metamorphism: Formation of metamorphic rock bodies that are hundreds of square kilometers in size

50. Essential questions How do metamorphic rocks form?
How do types of metamorphic rocks differ?

51. Metamorphic rock formation
Metamorphism: any process that affects the structure or composition of a rock in a solid state as a result of changes in temperature, pressure or the addition of chemical fluids.
Most metamorphic rocks form deep within the Earth’s crust.
Why?
High temperature and pressure

52. Metamorphic rock formation
Do not crystallize from magma
Different from igneous rocks
Do not result from erosion and deposition
Different from sedimentary rocks
Rocks change shape because of extreme temperature and pressure
Bend and twist into wrinkly layers

53. Temperature and Pressure
Under high temperature and pressure, rocks behave like bendable plastic, they can bend or fold
Plastic deformation: permanent change in shape by bending and folding
Occurs during uplifting events when techtonic plates collide and form mountains
This is how the texture changes

54. Temperature and Pressure
Parent rock: rock that changes during metamorphism.
Temperature depends on composition, between degrees Celcius
Gneiss= pronounced “nice”

55. Metamorphic rock identification
Classified into two groups based on texture (foliated and nonfoliated)
Changes in pressure can align minerals to form layers
Can look like clastic sedimentary rock
BUT presence of crystalline minerals in metamorphic rock differentiate it from sedimentary rock
Rock can also have blocky, interlocking crystals that are uniform in color

56. Foliated rocks Contain parallel layers of flat and elongated minerals
Layering is because of uneven distribution of pressure during metamorphism
Examples: phyllite and gneiss

57. Nonfoliated rocks
Metamorphic rocks that have mineral grins with a random, interlocking texture
No obvious alignment
Individual crystals look blocky and approximately equal in size
Minerals are generally uniform in color
Different from igneous rock that is generally multicolored (like granite)
Examples: amphibolite and quartzine
Amphibolite
Quartzine (morph from sandstone= primarily quartz)

58. Contact metamorphism
Magma comes in contact with existing rock, and its thermal energy and gases interact with the surrounding rock, forming new metamorphic rock.
Can increase crystal size or form new minerals and change rock

59. Regional metamorphism
Formation of metamorphic rock bodies that are hundreds of square kilometers in size
Changes in temperature and pressure and presence of chemical fluids
Can create entire mountain range of metamorphic rock
Examples: Himalayas (Asia), Appalachian Mountains (US)
Act on large volumes of rock

60. Metamorphic rocks

61. Rock identification lab
Crystal size?
Color?
Arrangement?
Special?
Igneous
Small (extrusive), large (intrusive)
Multi-colored
Interlocking (intrusive)
Light (silica), dark (Fe3+,Mg2+)
Sedimentary
See pebbles or grains but not really crystals
Uniform color
Varies, can have layering
Fossils?
Carbonate?
Metamorphic
Yes
Varies, can be uniform
Nonfoliated (blocky, interlocking crystals=uniform color)
Folliated (parallel layers of elongated minerals)
Crystals visible?
Single color or multi-colored?
Uniform size grains?
Layers?
What kind of rock?
Rock Identification? #1 #2 #3 #4

62. HOMEWORK Ch4 L.4 Vocabulary words on Flash Cards Outline Ch4 L.4
MEMORIZE FOR QUIZ
Outline Ch4 L.4
Lesson review questions
Page 137
Questions 1-8
QUIZ!!!!