dynamic crust practice - mr. jantzen's science...

Dynamic Crust Practice

1. Base your answer to the following question on the cross section below and on your knowledge of Earthscience. The cross section represents the distance and age of ocean-floor bedrock found on both sidesof the Mid-Atlantic Ridge.

A) 20 km toward the Mid-Atlantic RidgeB) 20 km away from the Mid-Atlantic RidgeC) 40 km toward the Mid-Atlantic RidgeD) 40 km away from the Mid-Atlantic Ridge

According to the cross section, every 1 million years, the ocean floor bedrock moves approximately

A) felsic, with a density of 2.7 g/cm3

B) felsic, with a density of 3.0 g/cm3

C) mafic, with a density of 2.7 g/cm3

D) mafic, with a density of 3.0 g/cm3

2. The basaltic bedrock of the oceanic crust is classifiedas

A) thicker B) more denseC) more granitic D) more felsic

3. Compared to the continental crust, the oceanic crust is

A) 3500°C and 0.4 million atmospheresB) 3500°C and 2.0 million atmospheresC) 5500°C and 0.4 million atmospheresD) 5500°C and 2.0 million atmospheres

4. Which combination of temperature and pressure isinferred to occur within Earth’s stiffer mantle?

A) density decreases and temperature decreasesB) density decreases and temperature increasesC) density increases and temperature increasesD) density increases and temperature decreases

5. What happens to the density and temperature of rockwithin Earth’s interior as depth increases?

A) more graniteB) more basaltC) more fossilsD) the same minerals and fossils

6. In the diagram below, letters A and B representlocations near the edge of a continent.

A geologist who compares nonsedimentary rocksamples from locations A and B would probably findthat the samples from location A contain

A) thicker, with a less dense granitic compositionB) thicker, with a more dense basaltic compositionC) thinner, with a less dense granitic compositionD) thinner, with a more dense basaltic composition

7. Compared to the oceanic crust, the continental crust isusually


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

8. On the map below, points A through D represent locations on Earth's surface.

Which location is positioned over a mantle hot spot?

A) mid-ocean ridges and rift valleysB) wide valleys and deltasC) ocean trenches and subduction zonesD) hot spots and island arcs

9. Which two features are commonly found at divergentplate boundaries?

A) crust B) rigid mantleC) stiffer mantle D) asthenosphere

10.The convection currents responsible for movingtectonic plates occur in which Earth layer?

A) subduction of a continental plateB) subduction of an oceanic plateC) divergence of a continental plateD) divergence of an oceanic plate

11. The Aleutian Islands extend westward from southernAlaska to form the northern boundary of the PacificOcean. These volcanic islands were formed by thenearby

A) crust B) asthenosphereC) outer core D) inner core

12. In which Earth layer are most convection currentsthat cause seafloor spreading thought to be located?

A) transform movementB) spreading movementC) subductionD) convergence

13. The map below shows California and a section of theSan Andreas Fault.

What is the primary geologic process occurringalong the San Andreas Fault?

A) absorbed by Earth's outer coreB) transmitted only through liquidsC) weak and detected only at nearby locationsD) not produced by this earthquake

14. A seismic station recorded the P-waves, but no S-waves, from an earthquake because S-waves were


15. Base your answer to the following question on the map below and on your knowledge of Earthscience. The map shows the coast of the northwestern United States. The Explorer and Gorda ridgesand plates are parts of the Juan de Fuca tectonic system.

A) B)

C) D)

The arrow on which map best shows the direction of movement of the Juan de Fuca Plate in relationto the Juan de Fuca Ridge?


A) B)

C) D)

16. Which cross section best represents the convection currents in the mantle beneath the Peru-ChileTrench?

A) divergent B) convergent C) transform D) complex

17. The block diagram below shows the boundary between two tectonic plates.

Which type of plate boundary is shown?

A) rigid mantle B) asthenosphereC) outer core D) inner core

18. Which part of Earth’s interior is inferred to haveconvection currents that cause tectonic plates tomove?


A)

B)

C)

D)

19. The cross section below represents a pattern of magnetic field reversals preserved in the igneousbedrock of the oceanic crust east of the Mid-Atlantic ridge.

Which cross section best represents the magnetic field pattern west of the Mid-Atlantic ridge?

20. Base your answer to the following question on the passage below.

Crustal Activity at Mid-Ocean Ridges

Mid-ocean ridges are found at one type of tectonic plate boundary. These ridges consist ofextensive underwater mountain ranges split by rift valleys. The rift valleys mark places where twocrustal plates are pulling apart, widening the ocean basins, and allowing magma from theasthenosphere to move upward. In some cases, mid-ocean ridges have migrated toward nearbymantle hot spots. This explains why mid-ocean ridges and mantle hot spots are found together atseveral locations.

A) convergent B) transform C) divergent D) complex

Which type of tectonic plate boundary is located at mid-ocean ridges?


21. Base your answer to the following question on the map of the Mid-Atlantic Ridge shown below.Points A through D are locations on the ocean floor. Line XY connects locations in North Americaand Africa.

A) B)

C) D)

In which cross section do the arrows best show the convection occurring within the asthenospherebeneath line XY?


A)

B)

C)

D)

22. Which cross section below best represents the crustalplate motion that is the primary cause of thevolcanoes and deep rift valleys found at mid-oceanridges?

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

23. The diagram below represents a cross section of aportion of the Earth's crust and mantle. LettersA, B, C, D and X identify locations within the crust.

The age of oceanic crust increases along a linebetween location X and location

24. Base your answer to the following question on theinformation and diagram below.

At intervals in the past, the Earth's magnetic fieldhas reversed. The present North magnetic pole wasonce the South magnetic pole, and the present Southmagnetic pole was once the North magnetic pole. Arecord of these changes is preserved in the igneousrocks that formed at mid-ocean ridges and movedaway from the ridges. The diagram below represents the pattern ofnormal and reversed magnetic polarity in the igneousrocks composing the ocean crust on the east side of amid-ocean ridge.

A)

B)

C)

D)

Which diagram below best shows the pattern ofnormal and reversed polarity on the west side of themid-ocean ridge?


25. Base your answer to the following question on the map below, which shows the tectonic plateboundaries near the East African Rift. Arrows show relative tectonic plate movement. A region ofAfrica is crosshatched.

A) B)

C) D)

Which diagram best represents the polarity of the magnetic field preserved in the ocean-floor bedrockfound on both sides of the Mid-Indian Ridge?


26. Base your answer to the following question on themap below which shows mid-ocean ridges andtrenches in the Pacific Ocean. Specific areas A, B, C, and D are indicated by shaded rectangles.

A) the revolution of the EarthB) the erosion of the Earth's crustC) shifting of the Earth's magnetic polesD) convection currents in the Earth's mantle

Movement of the crustal plates shown in the diagramis most likely caused by

A) hot liquid magma in the inner coreB) convection currents in the mantleC) volcanic eruptions along coastlinesD) meteor impacts in the ocean basins

27. The diagram below shows the collision of an oceanicplate and a continental plate.

Collisions between oceanic plates and continentalplates are thought to result primarily from

Base your answers to questions 28 through 30 on themap below, which shows seismograph recordingstations at locations A, B, and C. Location D is anearthquake epicenter. The distances from locations A and B to this epicenter are given in kilometers.

A) 11 min 15 sec B) 9 min 35 secC) 5 min 20 sec D) 4 min 20 sec

28. Approximately how long did the S-wave take totravel from the epicenter to location A?

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

29. At which location is the arrival-time differencebetween the P-wave and the S-wave greatest?

A) The bedrock below D is mostly basalt; below A,B, and C, the bedrock is mostly granite.

B) The bedrock below D is mostly granite; below A, B, and C, the bedrock is mostly basalt.

C) The bedrock below A, B, C, and D is mostlybasalt.

D) The bedrock below A, B, C, and D is mostlygranite.

30. Which statement best describes the igneous crustalbedrock below locations A, B, C, and D?


31. Base your answer to the following question on the diagram below and on your knowledge of Earthscience. The diagram represents a cut-away view of Earth's interior and the paths of some of theseismic waves produced by an earthquake that originated below Earth's surface. Points A, B, and C represent seismic stations on Earth's surface. Point D represents a location at the boundary betweenthe core and the mantle.

A) 2 minutes 20 seconds B) 6 minutes 40 secondsC) 8 minutes 20 seconds D) 15 minutes 00 second

Seismic station A is 5000 kilometers from the epicenter. What is the difference between the arrivaltime of the first P-wave and the arrival time of the first S-wave recorded at this station?


A) A is closest to the epicenter, and C is farthest from the epicenter.B) B is closest to the epicenter, and C is farthest from the epicenter.C) C is closest to the epicenter, and A is farthest from the epicenter.D) A is the closest to the epicenter, and B is the farthest from the epicenter.

32. The diagram below represents three seismograms showing the same earthquake as it was recorded atthree different seismic stations, A, B, and C.

Which statement correctly describes the distance between the earthquake epicenter and these seismicstations?

Answer KeyDynamic Crust Test Review

1. B2. D3. B4. A5. C6. A7. A8. A9. A10. D11. B12. B13. A14. A15. A16. C17. B18. B19. A20. C21. B22. C23. A24. C25. A26. D27. B28. B29. C30. A31. B32. C

dynamic crust practice - mr. jantzen's science...

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