1. Relative Dating Notes

2. Relative Dating
Relative dating is used to arrange geological events, and the rocks they leave behind, in a sequence. The method of reading the order is called stratigraphy (layers of rock are called strata). Relative dating does not provide actual numerical dates/ages for the rocks.

3. Relative Age
is the “age” of a rock or strata compared to the ages of other rocks or strata.

4. Relative Age

5. Principle of Superposition
as sedimentary rocks form, they are deposited on older rock layers.

6. Principle of Superposition
in undisturbed layers, the oldest is on the bottom and higher layers are younger.

7. Principle of Superposition
Oldest layer is on bottom (1)

8. Principle of Superposition
The Grand Canyon

9. Principle of Superposition
The Grand Canyon

10. Principle of original horizontality
The law states that layers of sediment were originally deposited horizontally under the action of gravity. 

11. Principle of Fossil Succession.
Also known as the principle of faunal succession, is based on the observation that sedimentary rock strata contain fossilized flora (plants) and fauna (animals), and that these fossils succeed each other vertically in a specific, reliable order that can be identified over wide horizontal distances.  

12. Principle of Cross- Cutting Relationships
An igneous/metamorphic rock, fault, or other geologic feature must be younger than any rock across which it cuts..

13. Crosscutting Relationships
Faults
Folds
Intrusions
Extrusions
Unconformities
Nonconformities
Disconformities

14. Video

15. Relative Dating: Flashback
List the principles of
Relative dating that apply
to the cross section on the right

16. Uniformitarianism
is the idea that the processes occurring on earth today are similar to those that occurred in the past.

17. Uniformitarianism
basically says “The present is the key to the past.”

18. Uniformitarianism
is the idea that geological features formed slowly over long periods of time.

19. Uniformitarianism
claims the Earth is 4.6 billion years old.

20. What does the Principle of Superposition say?
Sedimentary rocks form in rivers
Igneous rocks form faster than sedimentary
New rock layers form on top of older ones
There are billions of fossils on Earth

21. Which layer of rock is the oldest?1 2 3 4
They are all the same age

22. HOW OLD WOULD MOST GEOLOGISTS SAY THE EARTH IS?
6000 years
75,000 years
20 million years
4.6 billion years

23. According to what theory, is the earth 4.6 billion years old?
Catastrophism
Uniformitarianism
Geologism
Agism

24. Relative Dating Notes

25. Extrusions
are igneous rock layers that form on the surface when lava hardens.

26. Extrusions
are always younger than the layers over which they form.

27. Extrusion
Kubu Rock – Botswana, Africa

28. Intrusions
are igneous rocks that form when magma pushes up into rock layers.

29. Intrusions
are always younger than the rock layers they invade.

30. Intrusion

31. Intrusion

32. Intrusion
Devil’s Tower, WY

33. Intrusion
Devil’s Tower, WY

34. Stop and Summarize
Stand-up, Hand-up, Pair-up: Create a Venn Diagram with your partner.

35. In the image below identify as many intrusions and extrusions as you can!

36. Faults
are breaks in the earth’s crust. A fault is always younger than the rock it cuts through.

37. Faults

38. Faults
Shoshone Fault, CA

39. Folds
occur when rock layers are compressed together and bend or curve.

40. Folds
Guadalajara, Spain

41. Folds
Mojave Desert, CA

42. Stop and Summarize Write-Pair-Share: Create a Venn-Diagram
comparing Faults and Folds.

43. Identify the Cross-Cutting Relationships1 2 3

44. Flashback

45. SOME Relative Dating Practice
Write the correct order of events by numbering their occurrences.
Identify the cross-cut relationships in each cross section.

46. Relative Dating

47. Relative Dating

48. Relative Dating

49. Relative Dating Example

50. Unconformities
are gaps in the rock sequence (caused by the erosion of rock layers).

51. Angular Unconformity
occur when rock layers are tilted or uplifted, and then worn down by erosion and weathering.
Sediments are then deposited on top of these eroded layers.

52. Angular Unconformity

53. Angular Unconformity

54. Disconformities
are gaps created when erosion occurs on an overlying rock layer.

55. Disconformity

56. Nonconformity
are formed when sedimentary rock overlays igneous or metamorphic rocks.

57. Nonconformity

58. Flashback
What type of unconformity is E in the image to the right? List any cross-cutting relationships and order the events from oldest to youngest. E

59. Write a Sequence of event for the following geologic cross-section:

60. Draw the following geologic cross-section:
1.) 2 layers of sedimentary rock form.
2.) An extrusion forms on top of the two layers.
3.) A 3rd layer of sedimentary rock forms.
4.) An intrusion cuts through all of the rock layers, but not to the surface.
5.) A 4th layer of sedimentary rock forms.

61. Draw the following geologic cross-section:
1.) 2 layers of sedimentary rock form
2) Layers 1-2 are folded
3.) A 3rd sedimentary layer forms.
4.) A normal fault cuts through all the layers
5.) A 4th sedimentary layer forms.
6.) An intrusion cuts all the way to the surface forming an extrusion.

62. Top half of paper = Geologic History Must Include: At least…
5 sedimentary rock layers
3 different cross-cutting relationships
1 disconformity
Bottom half of paper = Geologic Cross Section
You will draw a geologic cross section numbering the sedimentary layers and lettering cross-cutting relationships. Also identify the type of unconformity.

63. Correlation
is using rock and fossil evidence to match up dating at different locations.

64. Correlation

65. Index Fossils
are used for dating the rock layers in which they are found.

66. Index Fossils
are species that were abundant all over the earth, but existed for shorter periods of time.

67. Index Fossil
trilobite

68. Index Fossil
ammonite

69. Index Fossil
Correlation using index fossils

70. Index Fossil
Correlation using index fossils

73. Exit Slip
If humans went extinct in the near future, would we make good index fossils? Explain your answer!
Hints: use your timescale, and the definition of index fossils.

74. What kind of cross-cut is shown to the right?
Intrusion
Extrusion
Folds
Unconformity

75. What kind of cross-cut is shown to the right?
Intrusion
Fault
Fold
Angular Unconformity

76. What kind of cross-cut is shown to the right?
Intrusion
Fault
Fold
Angular Unconformity

77. What is the name of the type of fossil is used to correlate rock layers at two or more different locations?
Mold
Petrified fossil
Index fossil
Trace fossil

78. Using correlation, Which two layers would you determine to be of the same age?
A & D
A & B
B & D
B & E

79. Paleontology Notes READY YOUR REMOTE FOR A QUICK REVIEW

80. What type of cross-cut appears at location e?
Fault
Fold
Nonconformity
Angular Unconformity

81. What type of cross-cut appears in the picture?
Fault
Disconformity
Nonconformity
Angular Unconformity

82. Absolute Age
is the age in years of a rock or other object (as determined by radiometric dating.

83. Radiometric Dating
entails finding the amount of certain radioactive elements left in a rock or object.

84. TURN TO YOUR JOURNAL PAGE

85. Draw a geologic cross-section with the following:
Write a geologic history that explains the order of occurrence of each event.
Draw a geologic cross-section with the following:
1.) At least 3 sedimentary rock layers
2.) At least 3 cross-cuts
(faults, folds, intrusions, extrusions, or unconformities, angular unconformities, nonconformity, disconformity)
Journal #5

86. Paleontology Notes READY YOUR REMOTE FOR A QUICK REVIEW

87. Which of the following is oldest?
Sandstone B
Sandstone A
Earthquake fault
Igneous Dike B

88. What type of cross-cut appears at location e?
Fault
Fold
Nonconformity
Angular Unconformity

89. What type of cross-cut appears in the picture?
Fault
Disconformity
Nonconformity
Angular Unconformity

90. “The important thing is to never stop questioning.”
- Albert Einstein

91. How much do you know about Paleontology?
Pre-Unit Questions
(Post-Unit)
Answer the following True/False Questions

92. How much do you know about Paleontology?
Pre-Unit Questions
(Post-Unit)
Answer the following True/False Questions

93. Many scientists theorize that dinosaurs were wiped out many years ago by some great catastrophe.
True
False

94. How much do you know about Paleontology?
TRUE. Obviously dinosaurs don’t exist today and they seem to disappear suddenly from the fossil record.

95. Fossils take millions of years to form.
True
False

96. How much do you know about Paleontology?
TRUE or FALSE?
FALSE. Fossils can form in less than a year depending on the conditions.

97. There are billions of fossils found all over the earth.
True
False

98. How much do you know about Paleontology?
TRUE. There are many fossils buried in the rock all over the planet. Over 99% of them are small marine plants and animals.

99. Dinosaurs are “giant lizards.”
True
False

100. How much do you know about Paleontology?
FALSE. Some were large, but many were not. The term dinosaur, coined in the 1800’s, does mean “terrible lizard,” but the average size of a dinosaur was that of a large dog.

101. JOURNAL # 6
Describe & discuss at least three new facts that you learned about paleontology while studying this unit.

102. RETURN YOUR REMOTE Classwork Assignments
1.) Journal # 6
2.) Relative Dating Geologic Cross-Sections WS
3.) Paleontology Test Review

103. Partner Assignment
1.) Draw a geologic Cross-Section on a blank piece of paper
2.) Include at least 5 sedimentary layers & 3 cross-cuts (intrusions, extrusions, faults, folds, or unconformities)
3.) Swap with a friend & have him/her number the events