1. Earth’s History Review
2018

2. How have organisms changed over time according to the fossil record?

3. Organisms have become more complex.
ANSWER
Organisms have become more complex.

4. What does the law of superposition state?

5. Bottom layers of rock are older than the layers above it.
Answer
Bottom layers of rock are older than the layers above it.

6. What is the geologic time scale a record of?

7. Answer
Earth’s History

8. What geologic time period do we live in?

9. Quaternary Time Period
Answer
Quaternary Time Period

10. According to the fossil record, when did the dinosaurs become extinct?

11. Answer
End of the Mesozoic Era

12. What are the four divisions of geologic time?

13. Pre-Cambrian, Paleozoic, Mesozoic, Cenozoic
Answer
Pre-Cambrian, Paleozoic, Mesozoic, Cenozoic

14. Paleozoic, Mesozoic, and Cenozoic are divisions in the geologic time scale called?

15. Answer
Eras

16. Eras are divided into what? Give some examples.

17. Periods
Cambrian, Ordovician, Silurian, Devonian, Permian, Triassic, Jurassic, Cretaceous, Tertiary, Quaternary

18. What is the main criterion that scientists use to decide where to place boundaries between major divisions of geologic time?

19. Major changes in geologic record. For example, mass extinction.
Answer
Major changes in geologic record. For example, mass extinction.

20. How are igneous rocks formed?

21. Igneous rocks formed from magma and lava that cools and hardens.
Answer
Igneous rocks formed from magma and lava that cools and hardens.

22. How are sedimentary rocks formed?

23. Sedimentary rocks form from sediments deposited on land or in water.
Answer
Sedimentary rocks form from sediments deposited on land or in water.

24. State the theory of Uniformitarianism.

25. Earth’s processes that happen today also happened in the past.
Answer
Earth’s processes that happen today also happened in the past.

26. Who is responsible for the Theory of Uniformitarianism?

27. Answer
James Hutton

28. Why is the geologic record important to scientists?

29. It helps piece together Earth’s history.
Answer
It helps piece together Earth’s history.

30. What is relative age and how is it determined?

31. The age of rock compared to the rock layers around it.
Answer
The age of rock compared to the rock layers around it.

32. What is absolute age and how is it determined?

33. Answer
Age of rock/object in years using a variety of methods. Determined using radiometric dating.

34. Which type of rock is easier to date using absolute dating? Why?

35. Igneous Rock because it has more pure minerals.
Answer
Igneous Rock because it has more pure minerals.

36. What is radiocarbon dating?

37. Determines the age of rocks using radiocarbon (carbon to nitrogen).
Answer
Determines the age of rocks using radiocarbon (carbon to nitrogen).

38. What is potassium- argon dating?

39. Answer
Radiometric dating method that measures the radioactive decay of potassium into argon.

40. What is uranium- lead dating?

41. Answer
Radiometric dating method that measures the radioactive decay of uranium to lead.

42. What can ice core samples tell us about Earth?

43. History of Earth’s climate.
Answer
History of Earth’s climate.

44. What does the Law of Crosscutting state?

45. Answer
A geologic feature that cuts another is the younger of the two features. Example: Intrusions

46. How would you describe a fossil that was discovered in a rock at the base of a cliff to a fossil in a rock found at the top of a cliff?

47. Answer
The fossil at the base of the cliff is older than the fossil that was found at the top of the cliff.

48. Explain how fossils and other materials can tell us about the conditions of an area at a specific time.

49. Answer
The types of organisms found in fossil record can help determine the climate and organisms that once roamed in an area. For example, fossils of sea creatures help us know that the area was once covered by water, and fossils of tropical plants in currently cold climates indicate that the climate was once much warmer.