Geology 100

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1. What is a natural hazard?

A normal Earth process that becomes hazardous when humans are exposed to it.

2. Can most natural hazards be eliminated?

No. Most are beyond human control.

3. Why should we anticipate disasters?

To save lives and money.

4. What can turn a hazard into a disaster?

Human exposure to the hazard.

5. What can turn disasters into catastrophes?

Social factors and increased impacts.

6. What is risk?

Probability × Potential Impact.

7. What does mitigation mean?

Reducing the effects of a hazard.

8. What is reactive action?

Responding after an event happens.

9. Give one example of reactive action.

Search and rescue.

10. Give another example of reactive action.

Firefighting.

11. What is anticipatory action?

Reducing vulnerability before an event.

12. Give one example of anticipatory action.

Enforcing building codes.

13. Why is anticipatory action useful?

It can greatly reduce loss of life and property.

14. What is land-use planning?

Regulating land use to create better social and environmental outcomes.

15. What are the five fundamental concepts of natural hazards?

Science helps predict hazards; risk helps decisions; hazards are linked; humans can worsen disasters; impacts can be minimized.

16. What is internal energy?

Heat from Earth's interior and Earth's gravity.

17. What hazards are associated with Earth's internal energy?

Earthquakes, volcanoes, and landslides.

18. What is external energy?

Energy from the Sun and objects from space.

19. What hazards are associated with external energy?

Weather, storms, drought, wildfires, flooding, and impact events.

20. What are human forces?

Human actions that alter natural systems.

21. Give an example of a human force changing a natural system.

Climate change, fires, or erosion.

22. What is the Geologic Cycle?

Processes that create, maintain, modify, and recycle Earth's surface materials.

23. What are the four major geologic sub-cycles?

Tectonic, rock, hydrologic, and biogeochemical cycles.

24. What is the tectonic cycle?

The creation, movement, and destruction of tectonic plates.

25. What does the tectonic cycle create?

Ocean basins, mountain belts, and volcanic chains.

26. What hazards does the tectonic cycle generate?

Earthquakes and volcanoes.

27. What is a mineral?

A natural inorganic solid with defined chemistry and crystalline structure.

28. What is a rock?

An aggregate of one or more minerals.

29. What are the three rock types?

Igneous, sedimentary, and metamorphic.

30. What is the hydrologic cycle?

The continuous movement of water through Earth systems.

31. What processes are part of the hydrologic cycle?

Evaporation, precipitation, and runoff.

32. What drives the hydrologic cycle?

The Sun and gravity.

33. What is a water reservoir?

A place where water is stored.

34. What is residence time?

The average time water stays in a reservoir.

35. What are biogeochemical cycles?

Cycles that move essential elements through Earth's systems.

36. Name four elements in biogeochemical cycles.

Carbon, oxygen, nitrogen, and phosphorus.

37. What is a natural service function?

A benefit that a natural hazardous process provides to the environment or humans.

38. How can volcanoes benefit humans or nature?

They can create new land.

39. How can earthquakes provide a natural service?

They can help capture resources.

40. How can floods provide a natural service?

They can distribute nutrients.

41. What are Earth's three chemical layers?

Crust, mantle, and core.

42. What is Earth's crust made of?

Rock.

43. What elements are common in the crust?

Oxygen, silicon, and aluminum.

44. Is the crust dense or less dense?

It is the least dense major chemical layer.

45. How thick is Earth's crust?

About 7–75 km.

46. What is the mantle made of?

Rock containing oxygen, silicon, magnesium, and iron.

47. About how thick is the mantle?

About 2,900 km.

48. What is the core made of?

Mostly iron and nickel.

49. Is the core dense or less dense?

Very dense.

50. About how large is the core's radius?

About 3,500 km.

51. What is differentiation?

The separation of materials based on density.

52. During differentiation, where do dense materials go?

They sink.

53. During differentiation, where do light materials go?

They rise.

54. What happened to iron in early Earth?

It sank toward the core.

55. What happened to water and gases in early Earth?

They rose toward the surface.

56. What are Earth's physical layers?

Lithosphere, asthenosphere/upper mantle, lower mantle, outer core, and inner core.

57. What is the lithosphere?

A rigid, strong layer containing the crust and uppermost mantle.

58. What is the lithosphere divided into?

Tectonic plates.

59. What is the asthenosphere?

A weak, plastic layer that can flow over time.

60. What do tectonic plates move on?

The asthenosphere.

61. What is the lower mantle?

A solid layer about 2,300 km thick.

62. What is the outer core?

A liquid layer.

63. What is the inner core?

A solid layer.

64. What is continental crust?

Thick, less-dense crust.

65. How thick is continental crust?

About 30–50 km.

66. What is oceanic crust?

Thin, denser crust.

67. How thick is oceanic crust?

About 6–7 km.

68. Which is denser: oceanic or continental crust?

Oceanic crust.

69. What is plate tectonics?

The theory that Earth's lithosphere is divided into moving plates.

70. What can plate movement cause?

Earthquakes, volcanoes, and mountains.

71. What is continental drift?

The idea that continents move over geologic time.

72. Who developed the continental drift hypothesis?

Alfred Wegener.

73. What was Alfred Wegener's occupation?

German meteorologist.

74. When did Wegener present continental drift?

1912.

75. What happened to Wegener's idea at first?

It was widely rejected.

76. What was Pangaea?

A supercontinent containing most of Earth's continental blocks.

77. When did Pangaea form?

About 330 million years ago.

78. When did Pangaea break apart?

About 200 million years ago.

79. What does Pangaea mean?

"All the earth."

80. What is paleoclimate?

The ancient climate of an area.

81. What can paleoclimate evidence show?

That continents were once connected.

82. What is fossil evidence for plate movement?

The same species are found on continents now far apart.

83. What is bathymetry?

The study of underwater depth of ocean floors.

84. What did sonar help scientists discover?

Mid-ocean ridges.

85. What is seafloor spreading?

New oceanic crust forms at mid-ocean ridges and moves away.

86. Where is oceanic crust youngest?

Near mid-ocean ridges.

87. Where is oceanic crust older?

Farther away from mid-ocean ridges.

88. What does GPS show about tectonic plates?

The direction and amount of plate movement.

89. What is the average plate movement rate?

About 5 cm per year.

90. What are the three types of plate boundaries?

Transform, divergent, and convergent.

91. What happens at a transform boundary?

Two plates slide past each other.

92. What is an example of a transform boundary?

The San Andreas Fault.

93. What is a major hazard at transform boundaries?

Strong to major earthquakes.

94. Does the lecture associate transform boundaries with volcanism?

No.

95. What happens at a divergent boundary?

Two plates pull apart.

96. What happens to magma at a divergent boundary?

It rises and forms new crust and lithosphere.

97. What is an example of a divergent boundary?

The Mid-Atlantic Ridge/Iceland.

98. What happens at a convergent boundary?

Two plates move toward each other.

99. What happens at an ocean-continent convergent boundary?

The denser oceanic plate subducts beneath the continental plate.

100. What are the three main types of faults?

Strike-slip, normal, and reverse.