Deck 2: Plate Tectonics: A Unifying Theory

Question 1

The eastern margin of the Ring of Fire is dangerous but is not a threat to human life.

Answer 1

False

Question 2

The idea that the position of continents has not been static over time is a relatively new concept, since the 1960's.

Answer 2

False

Question 3

Alfred Wegener proved the theory of continental drift on the basis of the geographic fit of the continents, paleontological, and geological evidence.

Answer 3

False

Question 4

Tropical climates existed in the past on continents which are now located in polar areas.

Question 5

Seeds from Glossopteris could have been distributed between continents by wind.

Question 6

Although the physical evidence for continental drift was substantial, the hypothesis lacked a viable mechanism for producing continental movement.

Question 7

New evidence from seafloor exploration and paleomagnetism provide such overwhelming evidence for tectonic plate movement that plate tectonic theory is accepted without a driving mechanism.

Question 8

Thermal convection cells in the mantle cause seafloor spreading.

Question 9

The plate tectonic theory is continually tested and refined even to present day.

Question 10

Magnetic minerals in similar age rocks from Europe and North America point to different magnetic pole locations indicating that the pole is variable and migrates over time.

Question 11

Tectonic plates interact along both passive and active continental margins.

Question 12

Supercontinents like Pangea will form in Earth's future.

Question 13

The supercontinent cycle hypothesis refers to the cyclical formation and breakup of supercontinents over a period of 500-600 million years.

Question 14

The California coast contains a convergent boundary.

Question 15

There is a convergent plate boundary off the east coast of Japan.

Question 16

The Red Sea and Gulf of Aden are examples of basins between converging plates (African and Arabian).

Question 17

In the thermal convection model, each plate corresponds to a single convection cell.

Question 18

If you were interested in prospecting for mineral resources, a plate tectonic map is a good place to begin your exploration.

Question 19

Hot spots are locations on Earth where new divergent plate boundaries are beginning to form.

Question 20

The first scientist to suggest a link between Africa and South America based on fossils was

A) Frank Taylor, 1910.
B) Edward Suess, 1855.
C) Snider-Pellegrini, 1858.
D) Harry Hess, 1962.
E) Alfred Wegener, 1912.

Question 21

Rates of plate motion are best determined by

A) measuring the change in distance between two continents over time
B) dating magnetic anomalies on the seafloor and calculating distance from the spreading center
C) using global positioning system to measure changes in locations over time
D) using hot spots to determine the direction of motion

Question 22

The first rock type similarities between Gondwana continents to be discovered were

A) continuity of mountain ranges.
B) fit of the coastlines.
C) glacial tillites.
D) marine sediments.
E) lake and swamp sediments of Pennsylvanian coal beds.

Question 23

Beside his hypothesis of continental drift, Frank Taylor (1910) correctly proposed that

A) the Moon was captured by Earth ~ 100 million years ago.
B) similar mountain ranges on either side of the Atlantic were produced by lateral movement of the continents.
C) the Mid-Atlantic Ridge was the zone along which the continents had separated.
D) that all of the southern hemisphere continents were once joined together.
E) the glacial deposits on Gondwana continents were formed by a single glacier.

Question 24

If the continents were once joined together, rocks and mountain ranges on the margins of each

A) should have formed under the same conditions.
B) should have formed in the same sequences.
C) should have formed at the same time.
D) should have the same structural trends and forces.
E) all of the above.

Question 25

Studies of paleomagnetism showed that

A) the northern and southern hemispheres had many times reversed position.
B) the ocean basins were young.
C) each continent had once had its own magnetic north pole.
D) the continents remained fixed and the north magnetic pole has moved.
E) all of the above

Question 26

That the oceanic crust is geologically young and the parallel magnetic striping pattern of basalts is symmetrical about oceanic ridges was conclusively shown by

A) radiometric dating of oceanic basalts and sequences from continents.
B) the unusually thin layer of oceanic sediments and the ages of contained fossils.
C) the existence of the same patterns in all ocean basins.
D) A and B
E) all of the above

Question 27

In plate tectonic theory, the lithosphere

A) is composed of oceanic and continental crust and upper mantle.
B) rests upon the buoyant asthenosphere.
C) is destroyed as fast as it is created.
D) moves over, and with, the asthenosphere.
E) none of the above

Question 28

The forces operating at continent-continent convergent plate boundaries are

A) tensional.
B) extensional.
C) lateral shearing (transform).
D) compressional.
E) compressional and tensional.

Question 29

A transform plate boundary may connect

A) a spreading ridge and subduction zone.
B) two spreading ridges.
C) two subduction zones.
D) A and C
E) all of the above

Question 30

The age and distribution of the Hawaiian Islands - Emperor Seamount chain show that the absolute motion of the Pacific Plate from the past to the present was

A) first north-northwesterly, then west-northwesterly.
B) first south-southeasterly, then east-southeasterly.
C) first north-northeasterly, then west-northeasterly.
D) first south-southwesterly, then west-southwesterly.
E) first north-northwesterly, then south-southeasterly.

Question 31

An acceptable hypothesis concerning the driving mechanism of plate tectonics must explain

A) past plate configurations and movement
B) present plate configurations and movement
C) future plate configurations and movement
D) B and C
E) all of the above

Question 32

The currently accepted hypothesis for the driving mechanism of plate tectonics is based on

A) density differences between oceanic and continental crust
B) the distribution of earthquakes and volcanoes
C) thermal convection cells in the asthenosphere and mantle
D) gravimetric and magnetic anamalies

Question 33

___________ ___________ first suggested in 1885 that South America, Africa, India, Australia, and Antarctica had once been a single landmass, and he gave the nameto this proposed supercontinent.

Question 34

___________flora was the name given to the group of plant fossils which was considered as evidence for the supercontinent Gondwana.

Question 35

The scientist who is credited with first seriously proposing continental drift earlier this century was___________ ___________ .

Question 36

___________is the name Wegener proposed for the supercontinent that was comprised of all of the continents.

Question 37

A___________ plate boundary is a collisional boundary between two plates, in most cases where plate subduction is occurring.

Question 38

The maximum age for oceanic crust is___________ million years.

Question 39

Pangaea began to fragment in the___________ Period.

Question 40

___________within the___________ is believed to be the mechanism for plate movement.

Question 41

Old, cold and dense oceanic crust is destroyed by___________ along___________ plate boundaries.

Question 42

New crust is formed along___________ ___________ .

Question 43

A___________ plate boundary runs through the state of California and it is named the___________ ___________ fault.

Question 44

The driving mechanism of plate tectonics is not well understood, but the two proposed models both involve___________ ___________ ___________ .

Question 45

How has deep-sea drilling confirmed sea-floor spreading?

Question 46

Which ocean does the Ring of Fire encircle?

Question 47

For what kinds of geologic activity is the Ring of Fire known?

Question 48

Why are convergent plate boundaries strongly associated with geological disasters?

Question 49

What presently accepted piece of evidence for continental drift/plate tectonics was first observed at least as early as 1620?

Question 50

What was the early geological explanation of fossil and rock similarities between Gondwana continents?

Question 51

What was one of the first mechanisms proposed to explain how continental movement could have occurred?

Question 52

What is the name of the northern landmass which Alexander du Toit proposed was located at the equator while Gondwana was at the South Pole?

Question 53

Which present-day continents belonged to the northern supercontinent first proposed by Alexander du Toit?

Question 54

What evidence was there that the northern continents were once joined and located along the equator?

Question 55

What are the lines of evidence which were cited for continental drift?

Question 56

What was the argument against the proposal that the coastline fit of South America and Africa was evidence of continental drift?

Question 57

How can the coastline fit be greatly improved, as demonstrated by Sir Edward Bullard, in 1965?

Question 58

Where are two sets of mountain ranges located which would be continuous if the continents on either side of the Atlantic are joined?

Question 59

Why did glacial deposits provide strong evidence of the existence of Gondwana?

Question 60

Why was the Glossopteris flora on Gondwana continents considered evidence for continental drift?

Question 61

Name a freshwater or land-dwelling reptile which was considered important fossil evidence linking the Gondwanan continents.

Question 62

How do certain rock types record the locations of past magnetic poles?

Question 63

Name the geophysicist who, along with his associates, discovered apparent polar wandering:

Question 64

Early paleomagnetic data gathered in Europe showed the paleomagnetic north pole apparently wandered with respect to Europe through time. What are three ways in which this data could be interpreted?

Question 65

What observations indicate that oceanic ridges are geologically very active?

Question 66

Who proposed the hypothesis of sea-floor spreading?

Question 67

What was the major difference between sea-floor spreading and continental drift?

Question 68

What does the symmetrical pattern of magnetic polarities about spreading ridges in oceanic crust basalts indicate?

Question 69

What is the primary cause of continental movement, according to the hypothesis of sea-floor spreading?

Question 70

The sea-floor spreading hypothesis was given important support with the interpretation of magnetic polarity striping by what three geologists?

Question 71

Briefly explain the mechanism of convective heat transfer.

Question 72

Briefly explain why the existence of guyots indicates that the sea floor is geologically young and that oceanic crust moves away from spreading ridges over time.

Question 73

According to the supercontinent cycle hypothesis, approximately how long is the cycle during which supercontinents form, break up, and reform?

Question 74

What is proposed as the cause of the break up of the supercontinents?

Question 75

What is one of the most convincing arguments for the supercontinent cycle hypothesis?

Question 76

What is an orogen?

Question 77

What two types of orogens does the supercontinent cycle hypothesis appear to explain?

Question 78

What present-day mountains of the eastern United States and Canada originally formed as an interior orogen?

Question 79

Explain the differences between continental drift and plate tectonics.

Question 80

How do geologists locate the boundaries of the plates?