Deck 3: Plate Tectonics: a Unifying Theory

Question 1

Harry Hess proposed the theory of seafloor spreading-the creation of new oceanic crust at mid-ocean ridges .

Answer 1

True

Question 2

Continental drift and plate tectonics refer to the same geological process.

Answer 2

False

Question 3

Continents have the best puzzle-like fit when placed together along their continental slopes.

Answer 3

True

Question 4

Convergent plate boundaries are characterized by formation of new oceanic crust.

Question 5

Earth's magnetic poles coincide with the geographic (rotational) poles.

Question 6

Earth's magnetic field reverses on a regular and predictable basis.

Question 7

The process of subduction creates new oceanic crust.

Question 8

Hot spots move with continental plates.

Question 9

The most effective method of calculating the rate of tectonic plate movement is to measure the thickness of a rock unit and divide that thickness by the age of the rocks.

Question 10

Sequences of deep-sea sediments, oceanic crust, and upper mantle rocks on land-called ophiolites-indicate the presence of an old convergent boundary.

Question 11

The Himalayan Mountains resulted from an orogeny.

Question 12

Earth's magnetic field is strongest at the equator and weakest at the poles.

Question 13

Both divergent and transform plate boundaries exist at mid-ocean ridges.

Question 14

A volcanic island arc is caused by the collision of two continental masses (e.g. a continental-continental convergent plate boundary).

Question 15

An orogeny is an episode of lithospheric plate downwarping that forms a sedimentary basin.

Question 16

The volcanic Emperor Seamount-Hawaiian Island chain resulted from a hot spot.

Question 17

Features associated with ancient continental rift zones include faults, dikes, and sills.

Question 18

Because tectonic plates move in response to mantle convection, each plate moves at the same rate.

Question 19

Alfred Wegener gave the name Pangaea to the supercontinent of landmasses that later broke apart.

Question 20

Magnetism results from the spin of electrons in some solids.

Question 21

The orientation of glacial striations was one piece of evidence supporting continental drift.

Question 22

Why are many petroleum and mineral deposits found at ancient convergent boundaries?

A) The lack of subduction prevented the deposits from being carried into the mantle.
B) Ophiolites have thrust natural resources to Earth's surface.
C) The absence of hydrothermal activity allowed materials to consolidate.
D) Heat is generated at convergent boundaries.
E) Divergent and transform plate boundaries do not generate heat and pressure.

Question 23

Which statement about the properties of Earth's crust is true at subduction zones?

A) Ocean crust is subducted because it is lighter than continental crust.
B) Continental crust is subducted because it is lighter than ocean crust.
C) Ocean crust is subducted because it is thicker than continental crust.
D) Continental crust is subducted because it is colder and denser than ocean crust.
E) Ocean crust is subducted because it is colder and denser than continental crust.

Question 24

Although plate boundaries influence the distribution of some metals resources, petroleum geologists cannot effectively use tectonics to explain petroleum concentrations.

Question 25

What surface feature is present on Earth above the rising limb of a mantle convection cell?

A) trench
B) spreading ridge
C) hot spot
D) continental  mountain chain
E) volcanic island arc

Question 26

What term refers to an episode of mountain building involving deformation-usually accompanied by igneous activity, metamorphism, and crustal thickening?

A) stratigraphy
B) accretion
C) bonding
D) ridge push
E) orogeny

Question 27

What is happening in the mantle beneath a subduction zone?

A) Hot mantle rock is rising, pulling down a cold ocean slab.
B) Cool mantle rock is rising, pulling down a warmer ocean slab.
C) The mantle is molten and the subducting slab sinks into it.
D) Relatively cool mantle rock is sinking, pulling down on a cold ocean slab.
E) Hot mantle rock is sinking, pulling down on a warm ocean slab.

Question 28

Pieces of lithosphere with completely different fossil content, stratigraphy, structural trends, and paleomagnetic properties than surrounding rocks are called ____.

A) terraces
B) concretions
C) hot spots
D) Wilson blocks
E) terranes

Question 29

A localized zone of melting (commonly thought to be stationary) below the lithosphere is called a(n) ____.

A) orogeny
B) hot spot
C) lava flow
D) chert
E) graywacke

Question 30

What is/are the major driver(s) of plate motion?

A) mantle convection only
B) gravity only
C) magnetism only
D) mantle convection and gravity
E) gravity and magnetism

Question 31

The oldest oceanic crust is slightly less than ____ years old.

A) 300,000
B) 4.6 billion
C) 70,000
D) 180 million
E) 3.96 billion

Question 32

The relative direction and average rate of plate movement can be calculated using ____.

A) accreted ophiolite studies
B) hot spots
C) subduction rate measurements
D) magnetic anomalies and satellite-laser ranging
E) spreading ridges

Question 33

Who proposed the concept of continental drift-a precursor to plate tectonics?

A) James  Hutton
B) William Smith
C) Charles  Darwin
D) Abraham  Werner
E) Alfred  Wegener

Question 34

Magma that is formed at subduction zones by partial melting in the descending plate commonly has a(n) ____ composition.

A) basaltic
B) granitic
C) andesitic
D) glassy
E) carbonate

Question 35

280,000,000 cm/115,000,000 years = 2.4 cm/year A magnetic anomaly that formed 115 million years ago and is 2,800 km away from the present-day mid-ocean ridge. What has the average rate of plate movement been over this time interval? (1 km = 100,000 cm)

A) 0.2 cm/year
B) 1.2 cm/year
C) 2.4 cm/year
D) 12 cm/year
E) 25 cm/year

Question 36

Most scientists did not support Wegener's theory of continental drift because his mechanism failed to satisfactorily explain continental movement.

Question 37

Which type of plate boundary is least likely to contain volcanoes?

A) oceanic-continental
B) divergent
C) convergent
D) transform
E) subduction

Question 38

Mantle convection cells are fueled with heat from the core.

Question 39

New oceanic crust is formed at ____.

A) subduction zones
B) transform faults
C) meandering rivers
D) glacial striations
E) mid-ocean ridges

Question 40

Faunal and floral diversity decrease when continents break up, and increase when continents join together in larger landmasses.

Question 41

The three major types of plate boundaries are ____________________, ____________________, and ____________________.

Question 42

Climatic and geographic barriers provide boundaries for ___________________, which are regions with a distinct assemblage of plants and animals.

Question 43

Rift valleys are associated with ____ plate boundaries.

A) divergent
B) transform
C) continental-continental convergent
D) oceanic-oceanic convergent
E) oceanic-continental convergent

Question 44

The study of paleomagnetism is possible because ____.

A) the magnetic minerals in rocks create Earth's magnetic field
B) most rocks contain no magnetic minerals
C) the magnetic minerals in rocks disrupt Earth's magnetic field
D) the magnetic minerals align toward the north magnetic pole at the Curie point
E) Earth's magnetic poles reverse on a regular and predictable time scale

Question 45

The present-day magnetic polarity of the Earth is called ____________________.

Question 46

One gravity-driven mechanism for plate movement is _______________________, which is caused by the higher elevation of ocean ridges in comparison to surrounding crust.

Question 47

Earth has____ major tectonic plates.

A) 2
B) 5
C) 7
D) 12
E) 20

Question 48

The three types of convergent plate boundaries are ____________________, ____________________, and ____________________.

Question 49

Which mechanism provides heat to Earth's interior?

A) gravitational contraction
B) meteorite bombardment
C) radioactive decay
D) subduction
E) core pressurization

Question 50

Harry Hess used oceanographic research data to propose the theory of ____________________.

Question 51

The first fossil evidence associated with the hypothesis of continental drift was ____ flora.

A) Glossaurus
B) Pecopteris
C) Neuropteris
D) Glossopteris
E) Messopteris

Question 52

Which line of evidence was not used by Alfred Wegener to support continental drift?

A) continental fit
B) similarity of rock sequences
C) continuity of mountain ranges on opposite continents
D) fossil evidence
E) paleomagnetic data

Question 53

Paleomagnetism measures the ____________________ and ____________________ of remnant magnetism in rocks.

Question 54

The oldest ocean crust is most likely to be found ____.

A) at mid-ocean ridges
B) at the bottom of rift valleys
C) in the middle of the ocean
D) adjacent to continental margins
E) in the deepest parts of the ocean

Question 55

At deep sea trenches, ____________________ crust is subducted into the ____________________.

Question 56

The temperature at which iron-bearing minerals gain their magnetic property is called their ____________________.

Question 57

Who was the first person to suggest that all of the continents had originally been joined together as the supercontinent Pangaea?

A) Alexander du Toit
B) Frank Taylor
C) Alfred Wegener
D) Edward Suess
E) Harry Hess

Question 58

The Earth's present magnetic field is described as "normal," meaning that the north magnetic pole is located ____, and the south magnetic pole is located ____.

A) at the south geographic pole; at the north geographic pole
B) in the Antarctic; in the Arctic
C) at the north geographic pole; at the south geographic pole
D) in the southern hemisphere; in the northern hemisphere
E) at the highest altitude; at the lowest altitude

Question 59

In analyzing continental drift, the name given to the northern supercontinent was ____.

A) Laurasia
B) Laurentia
C) Baltica
D) Gondwana
E) northern Pangaea

Question 60

In a(n) ____________________ plate boundary, lithosphere is neither created nor destroyed.

Question 61

What are terranes, and what information do they provide?

Question 62

Compare and contrast the three major types of plate tectonic boundaries. Discuss the tectonic features along each of these boundaries. Provide specific examples of each type of boundary.

Question 63

Explain the process of convection as it occurs on Earth , and include a diagram of a convection cell. Make sure your drawing shows Earth's core, mantle, crust, a spreading ridge, and a trench.

Question 64

The East African Rift Valley illustrates the formation of divergent plate boundary in a continental setting. Explain the four steps in the formation of a divergent plate boundary.

Question 65

Compare and contrast the concepts of slab-pull and ridge-push. How might mantle plumes influence plate movement?

Question 66

Compare and contrast the three types of convergent plate boundaries: oceanic-oceanic, continental-continental, and oceanic-continental. Detail the geologic processes occurring at each and identify by location the geologic features that form.

Question 67

Illustrate the effects of intraplate hot spots with specific examples. What do hot spots indicate about the movement of oceanic plates?

Question 68

Discuss the use of magnetic anomalies in the Atlantic Ocean to understand the separation of the supercontinent Pangaea and the formation of the present continents. How can we determine the rate of plate movement in the Atlantic Ocean?

Question 69

Using examples, discuss the evidence supporting the continental drift hypothesis.

Question 70

Using examples, discuss how orogenesis can influence speciation and the distribution of life.