1. Geologic History

2. Topic: Geologic Time Objectives: Day 1 of 3
I will know the major geologic events that have transformed our earth
I will know the geologic time scale and it’s major divisions

3. Quickwrite: In 2-3 sentences answer one of the questions below:
Where do you think all the oxygen in our atmosphere came from?
How long do you think Humans have been on this planet for????
Considering the age of the earth 4.6 BYO, When do you think life first appeared??

4. Geologic Time Scale
The geological time scale is the geologic history of the planet from formation to the present.
It is starts with large divisions of time called eons and is subdivided into successively smaller units such ass eras and period
The geologic time scale is based on dominant lifeforms, and mass extinction events

5. “Age of Water and Atmosphere” “Age of Plants, fish, and invertebrates”
Geologic Time Scale
Some of the major time eras include the:
Precambrian
Oceans and atmosphere form
Paleozoic
Invertebrates, plants and fish are the dominant forms of life
Mesozoic
Reptiles are the dominant forms of life
Cenozoic
Mammals are the dominant forms of life
“Age of Water and Atmosphere”
Precambrain
“Age of Plants, fish, and invertebrates”
Paleozoic
“Age of Reptiles”
Mesozoic
“Age of Mammals”
Cenozoic

6. What is the Geologic Time Scale?
Time scale from the beginning of earth to present
It is broken into time divisions such as Eras, & Periods that are based on the ____record, dominant life forms, and mass ____events
Answer Bank
Extinction
90%
Meteorites
Explosion
Fossil
Oxygen
Humans
Photosynthesis

7. Welcome to Earth 4.6 Billion Years ago
Earth Forms
Steam cooled and condensed into clouds,
These clouds Released precipitation (rain) for
millions of years, eventually forming our oceans
This was what our planet was like for
4 billion years--90% of earth’s History
Scientists call this period the Precambrian
Our oceans slowly formed over millions of years
As volcanoes released steam
One of these gases was steam or (H2O)
During the Precambrian,
our oceans and atmosphere formed
along with other important events
It was a harsh environment.
Meteorites bombarded our earth
And volcanoes spewed out gases
Precambrian
CO2
CO2
CO2
H2O
H2O
H2O N2

8. O2 O2 O2 CO2 + H2O  O2 + C6H12O6 4.6 billion years ago Earth Forms
Remember the recipe
for Photosynthesis is:
CO2 + H2O  O2 + C6H12O6
Another gas given off by volcanoes
is Carbon Dioxide (CO2)
About 2 billion years ago, primitive microscopic
single celled forms of life called
Phytoplankton began to fill the oceans
Another important event during the
Precambrian was the appearance
of the first single celled forms of life
These phytoplankton were very important
Because they helped create an oxygen
rich atmosphere for life to thrive in
These microscopic phytoplankton
absorbed CO2 from volcanoes and through
Photosynthesis released Oxygen (O2)
into our atmosphere
As Oxygen fill our atmosphere,
Our skies eventually became Blue
Precambrian O2 O2 O2
CO2
CO2
CO2

9. How did our atmosphere become rich in oxygen?
Answer Bank
Extinction
90%
Meteorites
Explosion
Fossil
Oxygen
Humans
Photosynthesis
Primitive phytoplankton and algae bacteria called stromatolites released oxygen into our atmosphere through _____ about 2 bya

10. Major Geologic Events of the Precambrian Era
4.5 bya- Moon forms
3.8 bya- first
oceans form
3.5 bya- 1st single
celled forms of life
Precambrian
1.1bya-1st continent
Rhodinia forms
1.3 bya- first multi
celled forms of life
2 bya- oxygen rich
atmopshere forms

11. What are major geologic events of the Precambrian Era?
Answer Bank
Extinction
90%
Meteorites
Explosion
Fossil
Oxygen
Humans
Photosynthesis
3.8 bya- oceans form
3.5 bya- 1st single celled forms of life
2 bya- ____ rich atmosphere forms
1.3 bya- 1st multi celled forms of life
1.1bya-1st continent Rhodinia forms

12. Paleozoic Era The Paleozoic Era witnessed an explosion of life
Precambrian
Paleozoic
The Paleozoic Era witnessed an explosion of life
Very shallow seas covered most of the earth
Through out these shallow seas lived some of the first complex
forms of life Including: invertebrates (shell fish), fish and plants
Some of these animals included trilobites,
ammonites (squid like creatures with shells)

13. Major Geologic Events of the Paleozoic Era
Precambrian

14. Major Geologic Events of the Paleozoic Era
245 mya- Mass Extinction 90% of all life
Precambrian
Paleozoic
322 mya- First reptiles appear
513 mya- First land plants appear
536 mya- 1st fish & invertebrates appear
570 mya- Explosion of life

15. What are major geologic events of the Paleozoic Era?
570 mya- _____ of life
536 mya- 1st fish & invertebrates 513 mya- 1st land plants
322 mya- 1st reptiles appear
245 mya- Mass Extinction ___% of all life
Answer Bank
Extinction 90
Meteorites
Explosion
Fossil
Oxygen
Humans
Photosynthesis

16. Mesozoic Era Precambrian The Mesozoic Era was the age of reptiles
Paleozoic
Mesozoic
The Mesozoic Era was the age of reptiles
& witnessed the evolution of the largest
animals to have ever walked the earth
The dinosaurs would eventually go extinct
and give rise to modern day birds
However, as we all know, these dinosaurs died
Out and left a world for other animals to inherit

17. Dinosaur Demise
There is mounting evidence that a large meteorite impact slammed into earth 65 mya ending the Cenozoic era
This impact would have caused widespread devastation and fires

18. Dinosaur Demise
Ash and smoke from fires could have blocked out enough sunlight changing the global climate; decimating and wiping out the cold blood reptiles

19. Major Geologic Events of the Mesozoic Era
Paleozoic
Precambrian

20. Major Geologic Events of the Mesozoic Era
Precambrian
Paleozoic
Mesozoic
65 mya- Mass extinction 60% of all life perishes
160 mya- First Birds appear
180 mya- Pangea breaks up
200 mya- First Mammals appear
200 mya- First Mammals appear
200 mya- First Mammals appear

21. What are major geologic events of the Mesozoic Era?
Answer Bank
Extinction
90%
Meteorites
Explosion
Fossil
Oxygen
Humans
Photosynthesis
Reptiles dominate
200 mya- 1st small Mammals appear
180 mya- Pangea breaks up
160 mya- 1st Birds
65 mya- Mass extinction 60% of all life perishes including dinosaurs due to large ______collision

22. Cenozoic Era Cenozoic With Dinosaurs gone, Mammals would inherit
Precambrian
Paleozoic
Mesozoic
Cenozoic
With Dinosaurs gone, Mammals would inherit
the earth and dominate the land
Large mammals thrive such as
Horses, Mammoths, and Primates
Mankind would evolve and inhabit
the earth expanding it’s population
Many Ice Ages came in went causing
the extinction of many large mammals

23. Major Geologic Events of the Cenozoic Era
Mesozoic
Paleozoic
Precambrian

24. Major Geologic Events of the Cenozoic Era
300,000 ya- Modern humans appear
Precambrian
Paleozoic
Mesozoic
Cenozoic
7 mya- First Human Ancestors appear
45 mya- One of the largest Ice ages occur

25. What are major geologic events of the Cenozoic Era?
Mammals dominate
45 mya- Major ice age event
7 mya- 1st Human ancestors appear
300,000ya- 1st modern ____
Present- your writing this down!!!!! (do not write )
Answer Bank
Extinction
90%
Meteorites
Explosion
Fossil
Oxygen
Humans
Photosynthesis

26. Summarize: List the events in order: Oldest to youngest
Mammals dominate the earth
Mass extinction 90% of all life wiped out
Reptiles dominate the earth
Explosion of life
Phytoplankton create oxygen rich atmosphere
Mass extinction 65% of all life wiped out including dinosaurs

27. Topic: Relative Dating
Objectives: Day 2 of 3
To learn how scientists use relative dating techniques to put geologic events in order
To learn how to apply the laws of geology (the law horizontality, law of superposition, law of cross-cutting relationships) to relative dating

28. Quickwrite: In 2-3 sentences answer one of the questions below:
How do you think scientists know which fossils are older and which fossils are younger?
What do you think causes mass extinctions?

29. Relative Dating 8. 7. 3. 4. Fault cuts through 2. 5. Magma Intrusion
The concept of dating rocks by putting geologic events in order
It does not give an exact age of rocks 8. 7. 3. 2.
4. Fault cuts through
5. Magma Intrusion 1.

30. Relative Dating 8. 7. 3. 5. Fault cuts through 2. 1.
The concept of dating rocks by putting geologic events in order
It does not give an exact age of rocks 8. 7. 3.
5. Fault cuts through 2. 1.
4. Magma Intrusion

31. What is Relative Dating?
The concept of dating rocks by putting geologic events in_______ 8.
Answer Bank
Younger
gap
Top
after
Bottom
Order
flat 7. 3.
5. Fault cuts through 2. 1.
4. Magma Intrusion

32. Law of Superposition
In layers of deposited sedimentary rock, the oldest rock layers are at the bottom and the rock layers become younger toward the top 3. 2. 1.

33. Law of Superposition
Principle of Superposition: States that the oldest rock layers are at the bottom and the rock layers become younger toward the top

34. Old rocks are at the bottom
The Law of Superposition: Old rocks formed on the bottom and young rocks are at the top
Young rocks
are at the top
Old rocks are
at the bottom

35. What is the Law of Superposition?
In layers of deposited sedimentary rock, the oldest rock layers are at the ____ and the rock layers become younger toward the ____ 3.
Answer
Bank
Younger
gap
Top
after
Bottom
Order
flat 2. 1.

36. Law of Horizontality Law of Horizontality: Rocks fall into
place forming flat,
horizontal layers

37. Law of Horizontality
Sediments are originally deposited in flat horizontal layers. If the rocks are folded or are laying at a steep angle, they must have been disturbed or tilted after they were originally deposited. 3. 3. 2. 2. 1. 1.

38. What is the Law of Horizontality?
Sediments are originally deposited in ____ horizontal layers. If the rocks are folded or at an angle, they must have been disturbed _____they were originally deposited.
Answer
Bank
Younger
gap
Top
after
Bottom
Order
flat 3. 3. 2. 2. 1. 1.

39. Unconformities
Think of layers of rock as pages of a history book
If we remove pages, the book is incomplete
An unconformity is when layers of rock are missing 3. 3. 2. 1. 1.

40. Unconformities: Here’s how it works!!!!5. 3. 4.
3. Unconformity
(weathering and erosion
create a gap in geologic time) 2. 1.

41. Unconformities
An unconformity is a gap in rock layers due to erosion and weathering or a break in the depositing of sediments (missing rock layers) 3. 3. 2. 1. 1.

42. What is an Unconformity?
An unconformity is a ____ in rock layers due to erosion and weathering or a break in the depositing of sediments (missing rock layers)
Answer Bank
Younger
gap
Top
after
Bottom
Order
flat 3. 3. 2. 1. 1.

43. Law of Cross Cutting Relationships
The law of cross cutting relationships states that a fault line or an igneous intrusion must be younger than the rock it cuts across. 3.
5. Fault cuts through 2. 1.
4. Magma Intrusion

44. What is the Law of Cross Cutting Relationships?
A fault line or an igneous intrusion must be _____ than the rock it cuts across.
Answer Bank
Younger
gap
Top
after
Bottom
Order
flat 3.
5. Fault cuts through 2. 1.
4. Magma Intrusion

45. Practice: Start with the oldest rock and work your way to the youngest1. 2. 3. 4. 5. 6. 7. 8.
Old H H H G F E G G D F F C C C B A
E Fault cuts through
E Fault cuts through B B A A
D Magma Intrusion
D Magma Intrusion

46. Practice: Start with the oldest rock and work your way to the youngest1. 2. 3. 4. 5. 6. 7. 8. 9.
Old K H H H G F E G G D F F C C C K K B E A
E Fault cuts through B B A A D
D Magma Intrusion

47. Practice: Start with the oldest rock and work your way to the youngest1. 2. 3. 4. 5. 6. 7. 8. 9.
Old K H H H G F E G G D F F C C C K K B E A
E Fault cuts through B B A A D
D Magma Intrusion

48. Practice: Start with the oldest rock and work your way to the youngest1. 2. 3. 4. 5. 6. 7. 8.
Old K J L Y X H G F

49. Summary:
The law of ______ states that Sediments are deposited in flat horizontal layers
When rock layers are missing in the geologic record we call it an _______
The law of ____ ____ relationships states that A fault line or an igneous intrusion must be younger than the rock it cuts across.
Answer Bank
unconformity
horizontality
Cross-cutting
superposition

50. Topic: Absolute Dating
Objectives: Day 3 of 3
To will how scientists use absolute dating to determine the exact age of rocks
I will know the concept of half life and radioactive decay

51. Quickwrite: In 2-3 sentences answer one of the questions below:
If you shook up 100 pennies in a box, how many do you think would be heads???? How many do you think would be tails????
Let’s say you have 100 dollars and you can only spend half of it every day. How much money would you have after 2 days????

52. Absolute Rock Dating
How do we know the earth is 4.6 billion years old?
How do we know when dinosaurs lived?
Thankfully, we can answer those questions by using Absolute Dating
Absolute Dating is a method used by geologists to determine the age of a rock or fossil
By analyzing the properties of atoms in rocks and fossils we can get a really accurate date for when the rock or fossil formed

53. What is Absolute Dating?
Absolute Dating is a method used by geologists to determine the exact _____ of a rock or fossil
It is different from relative dating because it gives an exact age
Answer
Bank
Element
Age
determine
decay

54. Radioactive Decay
Radioactive Decay: The decay of an atom of one element to form another element, an example would be when uranium becomes lead or carbon 14 becomes Nitrogen
For Example, after uranium-238 loses two protons and neutrons it becomes Lead- 206 which is stable and no longer changes
Uranium
Lead

55. What is Radioactive Decay?
The decay of an atom of one element into another _____
ex. uranium becomes lead
Answer
Bank
Element
Age
determine
decay

56. Parent and Daughter Material
Uranium is the
parent material
In the example of Uranium and Lead, which one is the Parent material and which one is the daughter material?
Uranium becomes Lead and is therefore the parent material
Lead is the stable daughter product
Lead is the
daughter material

57. Half-Life
Half life is the time it takes for half of the of the parent material to decay
For example, if I had one pound of Uranium it would take 4.5 billion years for half of it to decay
Therefore, we would only have half of what we started with after 4.5 billion years have passed
How much would we have after another 4.5 billion years have passed?

58. What is Half life?
Half life is the time it takes for half of the of the parent material to _____
Example: Lead
Answer
Bank
Element
Age
determine
decay

59. Who thinks they understand half-life?
1) What is the half life of uranium-238?
2) According to this diagram, how much uranium remains after 4.5 Billion years? Lead?
3) After 9 billion years, how much uranium is left? Lead?

60. Amount of Parent Material
= daughter material
½ life = 50,000 yrs
50% Daughter Material
50% Parent Material
100
75% Daughter Material
25% Parent Material 75
50,000 yrs
87.5% Daughter Material
12.5% Parent Material
Amount of Parent Material 50
50,000 yrs 25
50,000 yrs
50,000 yrs
50,000 yrs 1 2 3 4 5
Number of Half Lives

61. Old vs. Young Rock
We use Uranium half life to measure the age of the earth, which is very old
But, how would we measure something that is younger, like tree rings or artifacts from an ancient land?
Because Carbon-14 ( a radioactive form of carbon) has a half-life of 5,730 years, we can use it to date rocks that are much younger (unlike uranium, which has a half-life of 4.5 billion years)
After 5,730 years Carbon-14 will decay into stable Nitrogen

62. Radiometric Dating
To a geologist who studies rocks in order figure out earth’s history, these radioactive elements that decay are like a clock ticking away, keeping track of time since that’s passed since earth formed
Radiometric Dating: A dating method that uses the rate of decay of radioactive atoms in rocks by the amount of parent and daughter product to determine the absolute age of a rock

63. What is Radiometric Dating?
Dating method that uses the rate of decay of radioactive atoms in rocks by the amount of parent and daughter product to _____ the absolute age of a rock
Answer
Bank
Element
Age
determine
decay

64. Summarize:
Answer
Bank
Parent
age
Daughter
radiometric
Read the following scenario to complete the answer below: A piece of coal (made of carbon) from a cave man’s fire is found to have about 50% Carbon-14 and 50% Nitrogen. The half life of Carbon-14 is 5730 years.
Carbon-14 is the _____ material and Nitrogen is the _____material
The caveman’s coal and fire is ______years old
Scientist’s use _____dating to determine the absolute ____of rocks and fossils
100%
Carbon-14
50%
Carbon-14
50%
Nitrogen
5,730years