1. Earth’s History Test Review

2. Describe uniformitarianism

3. uniformitarianism
Earth is constantly changing since its creation The same forces that changed earth’s surface millions of years ago, are changing it now What are those forces?

4. uniformitarianism
Earth is constantly changing since its creation The same forces that changed earth’s surface millions of years ago, are changing it now What are those forces? Weathering, erosion, plate movement and resulting landforms and events (seafloor spreading, creation and destruction of crust, volcanoes, earthquakes, mountain building, creation of seas)

5. What is Continental Drift What evidence supports it?

6. Continental Drift Evidence
Matching fossils on separate continents
Matching rock formations on separate continents
Puzzle-like continent shapes
Tropical fossils in arctic climates

8. Fern fossil found in Antarctica

9. Lithosphere= crust + upper mantle Asthenosphere= soft, weak layer of mantle (magma)

10. What is the difference between relative and absolute age?

11. What is the difference between relative and absolute age?
Relative age: comparing rock layers and events to one another to determine age. Phrases such as older/younger than, first-second-third are used. 3 laws used to do this: original horizontality, superposition, cross-cutting relationships Absolute age: finding the actual age, or narrow range of time, of a rock layer by dating igneous material found in rock layers or “bracketing” using igneous volcanic ash. Using the half-life of radioactive material found in igneous rock allows us to do this.

12. What is the Law of Original Horizontality?

13. What is the Law of Original Horizontality?
Sedimentary rock is formed in horizontal layers

14. What is the Law of Superposition?

15. What is the Law superposition?
In undisturbed sedimentary rock layers, the oldest layer is at the bottom, youngest layer is at the top of the rock layers

16. What is the Law of Cross Cutting Relationships?

17. What is the Law of Cross Cutting Relationships?
Anything that cuts through a rock layer is YOUNGER than the rock layer it is in

18. Putting it together to find relative age:
Earth’s history is revealed in rock layers.
Sedimentary rock layers contain fossils, intrusions, cracks, unconformities and folds that tell us what was happening on earth’s surface at different points in time
Comparing fossils (index) and rock layers tell us what happened first, second…..relative age
Oldest layer is on the bottom, younger on top
Distortions in rock layers occurred after the layer(s) they changed

19. Oldest to youngest…… A B C D E F

20. F E C B
D (INTRUSION)
A (UNCONFORMITY) A B C D E F

21. OLDEST TO YOUNGEST… Y

22. OLDEST TO YOUNGEST… Y Z A
FAULT Q D Y

23. OLDEST TO YOUNGEST
 X A B C D E
F (10 MILLION YEARS OLD)

24. OLDEST TO YOUNGEST(BOTH ARE CORRECT)X F A B C D E F X A B C D E
 X A B C D E
F (10 MILLION YEARS OLD)

25. B C D E F (10 MILLION YEARS OLD)
Using the absolute age of the intrusion…… E, D, C, B and A are older than 10 million years old
 X A B C D E
F (10 MILLION YEARS OLD)

26. 1 2 3 4 Using the diagram to the right Describe the age of the fossil
Using layer 1
Using layer 4
Using layer 2 1 2 3 4

27. 1 2 3 4 Using the diagram to the right Describe the age of the fossil
The fossil is older than layer 1 The fossil is younger than layer 4 The fossil is the same age as layer 2
Using the diagram
to the right
Describe the age
of the fossil
Using layer 1
Using layer 4
Using layer 2 1 2 3 4

28. 1 2 3 4 Using the diagram to the right Describe the age
of the fossil B 1 2 3 4 A
B C

29. Fossil B is the same age as fossil C Fossil B is older than fossil A1 2 3 4 A
B C

30. What makes a good index fossil?

31. What makes a good index fossil?
Lived a brief period of time (not found in a lot of vertical rock layers)
Lived in a large global area (found in the same horizontal layers across the globe)
(Easy to see in a rock layer)

32. Which of these is probably an index fossilGA G CG C
CBA A B CA CB AC

33. Which of these is probably an index fossilGA G CG C
CBA A B CA CB AC
G…..IT IS FOUND IN A LARGE GEOGRAPHIC AREA (SAME HORIZONTAL LAYERS)
BUT DID NOT LIVE A LONG TIME (MULTIPLE LAYERS)

34. You have found an area of North Carolina with an abundance of fossils
You have found an area of North Carolina with an abundance of fossils. What kind of rock are you looking at? How do you know?

35. You have found an area of North Carolina with an abundance of fossils
You have found an area of North Carolina with an abundance of fossils. What kind of rock are you looking at? Sedimentary rock How do you know? Heat and pressure involved in igneous and metamorphic rock process destroys remains

36. What kind of evidence do we get from ice cores and tree rings?

37. What kind of evidence do we get from ice cores and tree rings?
Global climate evidence
Bubbles  CO2 levels in ancient air indicate temp levels. Also used in current computer model predictions of global warming.
Volcanic ash  evidence of volcanic eruptions
Pollen  spores evidence of environmental conditions
Tree rings
Ring width  very specific, local information about precipitation levels
Burn scars  forest fire evidence
Irregular banding  crowding, wind conditions

38. Tree Ring

39. Ice Core
Increasing levels of CO2 are linked to increasing global temperatures.
Using isotopes of Carbon we know that in the last 450 years, the increasing
CO2 levels are coming from human burning of fossil fuels, not volcanoes!

40. Absolute Age
Allows the calculation of ancient rock and fossil age..puts a number on age Half life of radioactive material found in volcanic intrusions & volcanic ash. (the time it takes half a radioactive parent sample to break down into a stable daughter material)

41. How much time has passed if 75% parent material remaining 25% parent material remaining

42. How much time has passed if % parent material remaining ½ yr (6 mos) % parent material remaining 2 yrs

43. Different radioactive isotopes are used to date different materials.
rocks
dead organisms,
<57,000 yrs old

44. Carbon-14 dating uses a radioactive isotope of carbon
Carbon-14 dating uses a radioactive isotope of carbon. It has a half life of 5,700 years. It has a useful time of ~60,000 years. It is ONLY USED on remains of LIVING THINGS
Other isotopes (uranium, chlorine..) have very long half lives (millions of years.) They have a useful range of millions to billions of years. They are used to date rock layers, fossils and remains of NONLIVING THINGS

45. Geologic Time Scale What is it How is it divided
Describe the major time periods

46. Geologic Time Scale
What is it? Fossil evidence in rock layers
How is it divided major events (extinctions & radiations)
Describe the major time periods
Precambrian: single celled life, most of earth’s history is in precambrian time, ends with mass radiation of life
Paleozoic era: most life in the sea, age of amphibians, ends with mass extinction
Mesozoic era: age of reptiles, dinosaurs, no ice—humid, ends with mass extinction…meteor strike
Cenozoic era: current, age of mammals

47. EONS – largest division of time
1. Hadean
2. Archean
3. Proterozoic
4. Phanerozoic
#1-3 make up Precambrian Time
Eons -> Eras -> Periods -> Epochs
Change in name is due major geologic or climatic events!!

48. PRECAMBRIAN TIME 90% of Earth’s history
Lasted nearly 4 billion years of Earth’s 4.6 billion years
Volcanic ash & dust ->clouds formed ->rain
Single-celled micro-organisms in ocean at end
No animals
No plants

49. 3 Eras make up the Phanerozoic Eon:
Paleozoic Era – “Age of Amphibians”
Mesozoic Era – “Age of Dinosaurs”
Cenozoic Era – “Age of Mammals”

50. Paleozoic Era = “Ancient”
544 mya – 248 mya
All life in ocean until end
Fish developed
Reptiles, Insects, Ferns developed – moving life onto land at end
Ends with a Mass Extinction kills 90% of all ocean species

51. Mesozoic Era = “Middle”
248 mya – 65 mya
Dinosaurs rule!
Small mammals, birds, flowering plants
Ends with Mass Extinction due to meteor strike off Mexico ->dust cloud blocked sunlight, killed plant life and affected food chain

52. Cenozoic Era =“Recent”
65 mya – Present
Large warm-blooded mammals, modern birds, flowering plants
Animals developed migration techniques
Tertiary Period
Quaternary Period = last 2 million yrs
Ice ages
1st modern human fossils = 100,000 yrs old
Humans are 7 seconds of 12 hour clock!!

53. Why study fossils?

54. Why study fossils?
They show us how
life has changed
over time. The
Geologic Time
Scale show us how
changes in earth’s
surface & climate
have affected changes
in organisms.

55. Over time,
Life began as single celled
Organisms and became
More diverse and complex