Dynamic Crust Review

1. The diagram below shows a cross section of sedimentary rock layers.

Which of the following statements about the deposition of the sediments best explains why these layers have been folded?(A) Sediments were deposited on an uneven curving seafloor.(B) Sediments were deposited after widespread volcanic eruptions.(C) Sediments were disturbed by crustal activity after deposition.(D) Sediments were deposited between two diverging oceanic plates.

2. The diagram below represents a cross section of a portion of the Earth's crust.

Which past activity in this region is suggested by the shape of these sedimentary rock layers?(A) crustal movements (C) horizontal sorting(B) widespread volcanic activity (D) glacial deposition

3. The diagram below shows a portion of the Earth's crust.

The movements indicated by the arrows represent the process of(A) faulting (B) metamorphism (C) folding (D) volcanism

4. Evidence of crustal subsidence (sinking) is provided by(A) zones of igneous activity at mid-ocean ridges (C) shallow-water fossils beneath the deep ocean(B) heat-flow measurements on coastal plains (D) marine fossiIs on mountaintops

Dynamic Crust Review5. The diagram below represents a section of the Earth's bedrock. The arrows show the direction of forces that are

gradually compressing this section.

Which diagram represents the most probable result of these forces?

(A) (B) (C)

(D)

6. The block diagram below represents a geologic cross section of a mountain range.

What action most likely formed this mountain range?(A) contact metamorphism (C) volcanic eruptions(B) earthquake faulting (D) glacial erosion

7. Fossils of organisms that lived in shallow water can be found in horizontal sedimentary rock layers at great ocean depths. This fact is generally interpreted by most Earth scientists as evidence that(A) the cold water deep in the ocean kills shallow-water organisms(B) sunlight once penetrated to the deepest parts of the ocean(C) sections of the Earth's crust have changed their elevations relative to sea level(D) organisms that live in deep water evolved from species that once lived in shallow water

8. Fossils of marine plants and animals are found in the bedrock of mountains many thousands of feet above sea level. The most likely reason for this observation is that(A) forces within the Earth caused uplift(B) the ocean level has dropped several thousand feet(C) the mountains were part of a mid-ocean ridge(D) transported materials were deposited at high elevations

9. Which observed feature would provide the best evidence of crustal stability?(A) folded, faulted, and tilted rock strata (C) marine fossils at elevations high above sea level(B) changed benchmark elevations (D) horizontal sedimentary layers

Dynamic Crust Review10. An observer discovers shallow-water marine fossils in rock strata at an elevation of 5,000 meters. What is the

best explanation for this observation?(A) The level of the ocean was once 5,000 meters higher.(B) Crustal uplift has occurred in this area.(C) Violent earthquakes caused crustal subsidence.(D) Marine organisms have evolved into land organisms.

11. The diagram below shows land features that have been disrupted by an earthquake.

Which type of crustal movement most likely caused the displacement of features in this area?(A) down-warping of the crust (C) folding of surface rock(B) vertical lifting of surface rock (D) movement along a transform fault

12. Base your answer to the following question on the map below, which shows crustal plate boundaries located along the Pacific coastline of the United States. The arrows show the general directions in which some of the plates appear to be moving slowly.

The best way to find the direction of crustal movement along the San Andreas fault is to(A) observe erosion along the continental coastline(B) measure gravitational strength on opposite sides of the fault(C) study the Earth's present magnetic field(D) match displaced rock types from opposite sides of the fault

13. A huge undersea earthquake off the Alaskan coastline could produce a(A) cyclone (B) thunderstorm (C) hurricane (D) tsunami

Dynamic Crust Review14. Base your answer to the following question on the diagrams below of geologic cross sections of the upper

mantle and crust at four different Earth locations, A, B, C, and D. Movement of the crustal sections (plates) is indicated by arrows, and the locations of frequent earthquakes are indicated by !. Diagrams are not drawn to scale.

Which diagram represents plate movement associated with transform faults such as those causing California earthquakes?(A) A (B) B (C) C (D) D

15. Which event provides direct evidence of crustal movement?(A) the erosion of the outside of a river curve(B) the displacement of rock strata during an earthquake(C) the deposition of sediments in the ocean(D) the weathering of rock to form a residual soil

16. The movement of tectonic plates is inferred by many scientists to be driven by(A) tidal motions in the hydrosphere (C) density differences in the troposphere(B) solidification in the lithosphere (D) convection currents in the asthenosphere

Dynamic Crust ReviewBase your answers to questions 17 and 18 on the map below, which shows the risk of damage from seismic activity in the United States.

17. Which New York State location has the greatest risk of earthquake damage?(A) Buffalo (B) Binghamton (C) Elmira (D) Plattsburgh

18. In the United States, most of the major damage expected from a future earthquake is predicted to occur near a(A) mid-ocean ridge and a divergent plate boundary (C) divergent plate boundary, only(B) convergent plate boundary, only (D) transform plate boundary and a hot spot

19. According to tectonic plate maps, New York State is presently located(A) above a mantle hot spot (C) near the center of a large plate(B) above a mid-ocean ridge (D) at a convergent plate boundary

20. Which two tectonic plates are separated by a mid-ocean ridge?(A) Indian-Australian and Eurasian (C) North American and Eurasian(B) Indian-Australian and Pacific (D) North American and South American

21. In which Earth layer are most convection currents that cause seafloor spreading thought to be located?(A) outer core (B) inner core (C) crust (D) asthenosphere

22. The two most abundant elements by mass in Earth’s crust are oxygen and(A) silicon (B) nitrogen (C) hydrogen (D) potassium

Dynamic Crust Review23. Arrows in the block diagram below show the relative movement along a tectonic plate boundary.

Between which two tectonic plates does this type of plate boundary exist?(A) Nazca Plate and South American Plate (C) North American Plate and Eurasian Plate(B) Eurasian Plate and Indian-Australian Plate (D) Pacific Plate and North American Plate

Dynamic Crust ReviewBase your answers to questions 24 and 25 on the information, map, and cross section below.

The map represents a portion of Earth's surface in the Pacific Ocean. The positions of islands, earthquake epicenters, active volcanoes, and the Tonga Trench are shown. Lines of latitude and longitude have been included. The cross section shows earthquakes that occurred beneath line XY on the map. Depth beneath Earths surface is indicated by the scale along the left side of the cross section, as are the range of depths for shallow, intermediate, and deep earthquakes. Distance from the trench is indicated by the scale along the bottom of the cross section.

24. The greatest number of earthquakes shown in the cross section occurred(A) at sea level (C) at a depth between 100 and 300 km(B) between sea level and a depth of 100 km (D) at a depth between 300 and 600 km

25. The Tonga Trench is located at the tectonic boundary between the Pacific Plate and the(A) Philippine Plate (C) Nazca Plate(B) Antarctic Plate (D) Indian-Australian Plate

26. Convection currents in the plastic mantle are believed to cause divergence of lithospheric plates at the(A) Canary Islands Hot Spot (C) Mariana Trench(B) Peru-Chile Trench (D) Iceland Hot Spot

27. Based on the theory of plate tectonics, it is inferred that over the past 250 million years North America has moved toward the(A) southwest (B) northwest (C) southeast (D) northeast

28. Compared to continental crust, oceanic crust is(A) less dense, more mafic, and thinner (C) less dense, more felsic, and thicker(B) more dense, more felsic, and thicker (D) more dense, more mafic, and thinner

Dynamic Crust Review29. The diagram below shows the interaction of two tectonic plates.

The type of plate boundary represented in the diagram most likely exists between the(A) Antarctic Plate and the African Plate (C) South American Plate and the African Plate(B) South American Plate and the Nazca Plate (D) Antarctic Plate and the Indian-Australian Plate

30. The diagrams below show four major types of fault motion occurring in Earth’s crust. Which type of fault motion best matches the general pattern of crustal movement at California’s San Andreas fault?

(A) (C)

(B) (D)

Dynamic Crust Review31. The diagram below shows some features of Earth’s crust and upper mantle.

Which model most accurately shows the movements (arrows) associated with the surface features shown in the diagram?

(A) (C)

(B) (D)

32. Which evidence causes most scientists to believe that seafloor spreading occurs at the mid-Atlantic Ridge?(A) Large sedimentary folds exist in the mantle near the ridge.(B) Oceanic crust on both sides of the ridge shows matching patterns of reversed and normal magnetic polarity.(C) Oceanic crust is oldest at the ridge.(D) Oceanic crust on both sides of the ridge is less dense than continental crust.

33. Beneath which surface location is Earth's crust the thinnest?(A) Old Forge, New York (C) San Andreas Fault(B) East Pacific Ridge (D) the center of South America

Dynamic Crust Review34. On the map below, line AB is drawn across several of Earth’s tectonic plates in the South Atlantic Ocean.

Which cross section best represents the plate boundaries and mantle movement beneath line AB?

(A) (C)

(B) (D)

Dynamic Crust ReviewBase your answers to questions 35 and 36 on the diagram below, which shows details of a section of a rift valley in the center of a mid-ocean ridge. The vertical lines in the diagram represent faults and fractures within the ocean floor bedrock.

35. The dark-colored lava flows shown in the diagram were pushed from the magma chamber onto the surface of the ocean floor. Which characteristics are present in the solid rock that formed when the lava flows cooled?(A) generally large grain size and mafic composition (C) generally large grain size and felsic composition(B) generally small grain size and felsic composition (D) generally small grain size and mafic composition

36. What will be the primary result of the continuation of the geologic processes indicated at this location?(A) Continental crust will be forced downward. (C) New oceanic crust will form.(B) Earths circumference will increase. (D) Earths magnetic field will reverse direction.

37. Which inference is supported by a study of the Earth's magnetic rock record?(A) The Earth's magnetic poles appear to have changed location over time.(B) The Earth's magnetic field is 50 times stronger now than in the past.(C) The Earth's magnetic poles are usually located at 0 latitude.(D) The Earth's magnetic field is only 2 million years old.

38. Compared to Earth's oceanic crust, Earth's continental crust is(A) thinner and composed of basalt (C) thinner and composed of granite(B) thicker and composed of granite (D) thicker and composed of basalt

Dynamic Crust Review39. The diagram below shows a tectonic plate boundary.

Which mantle hot spot is at a plate boundary like the one shown in this diagram?(A) Hawaii Hot Spot (B) Galapagos Hot Spot (C) Yellowstone Hot Spot (D) Canary Hot Spot

40. Which diagram correctly shows how mantle convection currents are most likely moving beneath colliding lithospheric plates?

(A) (B) (C) (D)

41. Which evidence supports the theory of ocean floor spreading?(A) The pattern of magnetic orientation of rocks is similar on both sides of the mid-ocean ridge.(B) The density of oceanic crust is greater than the density of continental crust.(C) The rocks of the ocean floor and the continents have similar origins.(D) In the ocean floor, rocks near the mid-ocean ridge are cooler than rocks near the continents.

42. The study of how seismic waves change as they travel through Earth has revealed that(A) Earth’s outer core is liquid because S-waves are not transmitted through this layer(B) P-waves travel more slowly than S-waves through Earth’s crust(C) seismic waves travel more slowly through the mantle because it is very dense(D) Earth’s outer core is solid because P-waves are not transmitted through this layer

43. Which statement most accurately compares Earth’s crust and Earth’s mantle?(A) The crust is thicker and more dense than the mantle.(B) The crust is thinner and less dense than the mantle.(C) The crust is thicker and less dense than the mantle.(D) The crust is thinner and more dense than the mantle.

Dynamic Crust Review44. Which cross section below best represents the crustal plate motion that is the primary cause of the volcanoes and

deep rift valleys found at mid-ocean ridges?

(A) (B) (C) (D)

45. The map below shows the present-day locations of South America and Africa. Remains of Mesosaurus, an extinct freshwater reptile, have been found in similarly aged bedrock formed from lake sediments at locations X and Y.

Which statement represents the most logical conclusion to draw from this evidence?(A) Mesosaurus came into existence on several widely separated continents at different times.(B) The present climates at locations X and Y are similar.(C) Mesosaurus migrated across the ocean from location X to location Y.(D) The continents of South America and Africa were joined when Mesosaurus lived.

46. Which difference between gabbro bedrock and granite bedrock causes seismic waves to travel faster in gabbro than in granite?(A) Gabbro has greater permeability than granite.(B) Gabbro has a darker color than granite.(C) Gabbro is made of smaller mineral grains than granite.(D) Gabbro is more dense than granite.

Dynamic Crust Review47. The diagram below represents the pattern of normal and reversed magnetic polarity and the relative age of the

igneous bedrock composing the ocean floor on the east side of the Mid-Atlantic Ridge. The magnetic polarity of the bedrock on the west side of the ridge has been deliberately left blank.

Which diagram best shows the magnetic pattern and relative age of the igneous bedrock on the west side of the ridge?

(A) (B) (C) (D)

48. Base your answer to the following question on the diagram below, which shows models of two types of earthquake waves.

Model A best represents the motion of earthquake waves called(A) S-waves (shear waves) that travel slower than P-waves (compressional waves) shown in model B(B) S-waves (shear waves) that travel faster than P-waves (compressional waves) shown in model B(C) P-waves (compressional waves) that travel faster than S-waves (shear waves) shown in model B(D) P-waves (compressional waves) that travel slower than S-waves (shear waves) shown in model B

Dynamic Crust Review49. Base your answer to the following question on the cross-sectional view of Earth below, which shows seismic

waves traveling from the focus of an earthquake. Points A and B are locations on Earth’s surface.

Which statement best explains why only one type of seismic wave was recorded at location B?(A) S-waves cannot travel through the liquid outer core.(B) P-waves cannot travel through the solid inner core.(C) S-waves cannot travel through the liquid inner core.(D) P-waves cannot travel through the solid outer core.

50. When a continental crustal plate collides with an oceanic crustal plate, the continental crust is forced to move over the oceanic crust. What is the primary reason that the continental crust stays on top of the oceanic crust?(A) Continental crust contains more mafic minerals. (C) Continental crust is less dense.(B) Continental crust melts at higher temperatures. (D) Continental crust deforms less easily.

51. The observed difference in density between continental crust and oceanic crust is most likely due to differences in their(A) rate of cooling (B) thickness (C) porosity (D) composition

52. What is Earth’s inferred interior pressure, in millions of atmospheres, at a depth of 3500 kilometers?(A) 1.9 (B) 2.8 (C) 5500 (D) 6500

53. What is the origin of fine-grained igneous rock?(A) silt that settled quickly in ocean water (C) lava that cooled slowly on Earth’s surface(B) lava that cooled quickly on Earth’s surface (D) silt that settled slowly in ocean water

54. What is the inferred temperature at the boundary between Earth’s stiffer mantle and outer core?(A) 2,500°C (B) 4,500°C (C) 5,000°C (D) 6,200°C

Dynamic Crust Review55. Base your answer to the following question on the map below which shows the locations of deep-sea core

drilling sites numbered 1 through 4. The approximate location of the East Pacific Ridge is shown by a dashed line. Point A is located on the East Pacific Ridge.

Compared to the thickness and density of the continental crust of South America, the oceanic crust of the Pacific floor is(A) thicker and less dense (C) thicker and more dense(B) thinner and more dense (D) thinner and less dense

56. Base your answer to the following question on the cross section below, which shows a portion of Earth’s crust and upper mantle near a mid-ocean ridge.

If crust 2 represents basalt with normal magnetic polarity, what does crust 3 most likely represent?(A) sedimentary rock with normal magnetic polarity (C) igneous rock with normal magnetic polarity(B) sedimentary rock with reversed magnetic polarity (D) igneous rock with reversed magnetic polarity

57. Which conditions normally can be found in Earths asthenosphere, producing a partial melting of ultramafic rock?(A) temperature = l,000°C; pressure = 10 million atmospheres(B) temperature = 2,000°C; pressure = 0.1 million atmospheres(C) temperature = 3,500°C; pressure = 0.5 million atmospheres(D) temperature = 6,000°C; pressure = 4 million atmospheres

Dynamic Crust Review58. Base your answer to the following question on the map below. The map shows the continents of Africa and

South America, the ocean between them, and the ocean ridge and transform faults. Locations A and D are on the continents. Locations B and C are on the ocean floor.

Which table best shows the relative densities of the crustal bedrock at locations A, B, C, and D?

(A) (C)

(B) (D)

59. In which layer of Earth’s interior is the pressure inferred to be 1.0 million atmospheres?(A) outer core (B) inner core (C) rigid mantle (D) stiffer mantle

60. Most inferences about the characteristics of Earth’s mantle and core are based on(A) well drillings from Earth’s mantle and core(B) the behavior of seismic waves in Earth’s interior(C) chemical changes in exposed and weathered metamorphic rocks(D) comparisons between Moon rocks and Earth rocks

Dynamic Crust Review61. Which graph best shows the inferred density of Earth’s interior as depth increases from the upper mantle to the

lower mantle?

(A) (C)

(B) (D)

62. Base your answer to the following question on the diagram below, which shows a portion of Earth’s interior. Point A is a location on the interface between layers.

The temperature of rock at location A is approximately(A) 600°C (B) 1,000°C (C) 2,600°C (D) 3,000°C

Dynamic Crust Review63. Base your answer to the following question on the diagram below, which shows a cutaway view of Earth in

which the interior layers are visible. The paths of earthquake waves generated at point X are shown. A, B, C, and D are locations of seismic stations on Earth's surface, and point E is located in Earth's interior.

The actual rock temperature at point E is inferred to be approximately(A) 1,500ºC (B) 2,900ºC (C) 5,000ºC (D) 6,200ºC

64. The pressure at the interface between the mantle and the outer core of Earth is inferred to be approximately(A) 1.0 million atomspheres (C) 3.0 million atmospheres(B) 1.4 million atmospheres (D) 3.4 million atmospheres

65. Earth’s outer core and inner core are both inferred to be(A) solid (C) composed of a high percentage of iron(B) liquid (D) under the same pressure

66. Andrija Mohorovicic discovered the interface between the crust and the mantle that is now named for him. His discovery of the “Moho” was based on analysis of(A) seismic waves (B) continental coastlines (C) landscape boundaries (D) erosional surfaces

67. Geologists have used information about the composition of meteorites to make inferences about Earth’s(A) atmospheric structure (C) asthenosphere location(B) core properties (D) continental-crust thickness

68. The rock between 2,900 kilometers and 5,200 kilometers below the Earth's surface is inferred to be(A) an iron-rich liquid (B) a silicate-rich solid (C) a silicate-rich liquid (D) an iron-rich solid

Dynamic Crust Review69. Base your answer to the following question on the diagram below which represents Earth's interior zones.

The composition of Earth's core is thought to be the same as the composition of many(A) volcanic ashes (B) basalts (C) meteorites (D) granites

Base your answers to questions 70 and 71 on the block diagram below. The diagram shows the tectonic plate boundary between Africa and North America 300 million years ago, as these two continents united into a single landmass. The arrows at letters A, B, C, and D represent relative crustal movements. Letter X shows the eruption of a volcano at that time.

70. Identify the type of tectonic motion represented by the arrows shown at A, B, and C.

71. Identify the type of tectonic plate motion represented by the arrow shown at D.

Dynamic Crust ReviewBase your answers to questions 72 through 75 on the map and block diagram below. The map shows the location of North Island in New Zealand. The block diagram shows a portion of North Island. The Hikurangi Trench is shown forming at the edge of the Pacific Plate. Point X is at the boundary between the lithosphere and the asthenosphere.

72. Describe one action that people on North Island should take if a tsunami warning is issued.

73. Describe the type of tectonic plate motion that formed the Hikurangi Trench.

74. On what tectonic plate are both North Island and White Island located?

75. State the approximate temperature at point X.

______________ ºC

Dynamic Crust ReviewAnswer Key

Dynamic Crust ReviewAnswer Key

1. C

2. A

3. A

4. C

5. B

6. B

7. C

8. A

9. D

10. B

11. D

12. D

13. D

14. D

15. B

16. D

17. D

18. D

19. C

20. C

21. D

22. A

23. D

24. D

25. D

26. D

27. B

28. D

29. B

30. D

31. C

32. B

33. B

34. B

35. D

36. C

37. A

38. B

39. B

40. B

41. A

42. A

43. B

44. B

45. D

46. D

47. A

48. C

49. A

50. C

51. D

52. A

53. B

54. C

55. B

56. D

57. B

58. D

59. D

60. B

61. B

62. C

63. C

64. B

65. C

66. A

67. B

68. A

69. C

70. Examples: –transform movement –faulting –The plates slide past each other.

71. Examples: –subduction –convergence

72. Examples: — move to higher ground — evacuate — move inland

73. Examples: — subduction — convergence — plate collision

74. Indian-Australian Plate.

75. Any value from 500°C to 1200°C.