Chapter 5 - The Tectonic Cycle

Question 1

Along what type of plate boundary does subduction occur?

A. transform

B. divergent

C. convergent

Answer 1

C. convergent

Question 2

The volcanic mountain range of the Andes is defined as a:

a. continental volcanic arc
b. Himalaya-like mountain zone
c. volcanic island arc
d. mini supercontinent

Answer 2

a. Continental volcanic arc

Question 3

Since Pangaea, the lithosphere has broken into nine major plates and a large number of smaller plates

true or false

Answer 3

True

Question 4

Large mountain ranges are characterized by significant negative gravity anomalies because of their deep, low-density routes

true or false

Answer 4

True

Question 5

What type of plate margin is the majority of the rim surrounding the Pacific Ocean?

a. Active
b. passive

Answer 5

A. Active

Question 6

When both plates of a converging pair are by low-density continental crust, neither plate will undergo subduction

true or false

Answer 6

False

Question 7

As the plates of a transform fault grind past one another their edges may grab and lock, forcing the rocks on both sides to flex and bend

true or false

Answer 7

True

Question 8

The highest temperature at which magnetic material can retain permanent magnetization is called the:

a. Newton point
b. centigrade scale
c. Fahrenheit proximity
d. Curie point

Answer 8

d. Curie point

Question 9

Where is active sea-floor spreading occurring today?

a. Lake Michigan
b. the great Salt Lake
c. the Mississippi River
d. the Athabasca River
e. the Red Sea
f. saline Creek

Answer 9

e. The Red Sea

Question 10

How does plate tectonics influence the composition of ocean water?

a. material from the core seeps into the ocean via submarine volcanoes
b. none of the choices
c. all of the choices
d. oceanic trenches from subduction zones trap salts and minerals thereby changing the overall ocean water composition
e. submarine volcanoes along mid-ocean ridges lead to chemical reactions between the ocean water in the hot rocks of the seafloor

Answer 10

e. submarine volcanoes along mid-ocean ridges lead to chemical reactions between the ocean water in the hot rocks of the seafloor

Question 11

When a plate capped by a continental crust converges with a plate capped by an oceanic crust, the continental plate will undergo subduction

true or false

Answer 11

False

Question 12

What type of plate boundary created Iceland?

a. transform
b. convergent
c. divergent

Answer 12

c. Divergent

Question 13

Assume there is a mountain range with a deep root of low-density continental rock extending into the underlying asthenosphere. Would this produce a negative or positive gravity anomaly?

a. Negative
b. need more information answer this question
c. positive

Answer 13

a. Negative

Question 14

Subduction zones are marked by deep trenches where ocean Lithosphere sinks into the asthenosphere.

true or false

Answer 14

True

Question 15

Measuring the speed and direction of movement of lithospheric plates requires a fixed frame of reference, such as distant stars

true or false

Answer 15

True

Question 16

How does hotspots and plate tectonics account for the islands of the Hawaiian island chain varying in age?

a. the volcanic hotspot in the middle of the Pacific Ocean is due to the divergence of the East Pacific rise
b. as molten material continually seeped from the hotspot, an island(s) would form. As the Pacific Plate continued to move the island locked to the Pacific Plate would move as well. A new island with then form from the hotspot.
c. hotspots and plate tectonics cannot for the age variability

Answer 16

b. as molten material continually seeped from the hotspot, an island(s) would form. As the Pacific Plate continued to move the island locked to the Pacific Plate would move as well. A new island with then form from the hotspot.

Question 17

What was the first evidence that led Alfred Waggoner to suspect the continents were once connected?

a. the continents simply looked like they fit together, especially Africa and South America
b. the clock like ebb and flow of the tides
c. Alfred Wegener discovered marine sediments in the Himalaya Mountains
d. the direction that the currents moved

Answer 17

a. the continents simply looked like they fit together, especially Africa and South America

Question 18

Apparent polar wandering is best explained by:

a. the movement of earth’s axis of rotation
b. The movements of continents
c. magnetic reversals
d. in truth, the magnetic poles wander significantly

Answer 18

b. The movements of continents

Question 19

Where are the youngest seafloor rocks found?

a. nearest to the rift valleys of the midocean ridges
b. within the deep-sea trenches
c. nearest the continental margins
d. evenly distributed over the ocean basins

Answer 19

a. nearest to the rift valleys of the midocean ridges

Question 20

A typical rate of seafloor spreading along the mid-Atlantic Ridge is

a. 2 to 4 feet per year
b. 2 to 4 cm per year
c. 2 to 4 inches per year
d. 2 to 4 m per year

Answer 20

b. 2 to 4 cm per year

Question 21

What is the source of Earth’s magnetic field?

a. the sun
b. the moon
c. the moving electric field within the liquid outer core
d. the lithosphere

Answer 21

c. The moving electric field within the liquid outer core

Explanation: as a result of the Earth’s rotation, the molten iron of the outer core is continually flowing around the solid inner core. The flowing stream of molten iron causes an electrical current to flow in the outer core, and the electrical current, in turn, generates the magnetic field

Question 22

How does lava carry a record of Earth’s changing magnetic field?

a. the magnetite in the magma, when the temperature exceeds 580°C, will align in the direction of an external magnetic field
b. the magnetite in the magma, when the temperature drops below 580°C, will align in the direction of an external magnetic field

Answer 22

b. the magnetite in the magma, when the temperature drops below 580°C, will align in the direction of an external magnetic field

Explanation: Above the Curie Point this thermal agitation of atoms is such that permanent magnetism is impossible. The Curie point for the mineral magnetite is 580°C; above 580°C, the atomic magnets within the magnetite are randomly oriented. If the magnetite cools to below 580°C, however, the tiny atomic magnets begin to align to whatever magnetic field is influencing them. Eventually they are pinned within the crystal structure, and will not change in future

Question 23

The magnetic greens in oceanic crust, when solidified, are frozen in the direction of the magnetic field. Changing directions of magnetic inclination as seen around spreading centres indicates changes in the magnetic pole position over time

true or false

Answer 23

True

Explanation: As long as the volcanic rocks are not destroyed by weathering, metamorphism, or melting, they carry their paleomagnetism, or ancient magnetism, providing a record of Earth’s magnetic field long ago

Question 24

Absolute speed refers to the movement of the plate in comparison to a neighbouring plate

true or false

Answer 24

False

Explanation: absolute speed requires a fixed or stationary frame of reference

Question 25

If plate A is moving east at a rate of 5 cm per year, and plate B is moving west at a rate of 3 cm per year, to an observer standing on plate B what is the relative speed of plate A (assume that the margin between the two plates is a transform boundary)? a. 2 cm per year towards the east b. 8 cm per year towards the east c. 2 cm per year towards the West d. 8 cm per year towards the West

Answer 25

b. 8 cm per year towards the east

Question 26

Which of the following locations are moving the fastest? a. Mid-Atlantic Ridge b. South-East Indian rise c. East-Pacific Rise d. San Andreas Fault (transform boundary)

Answer 26

c. East-Pacific Rise

Question 27

What is the Earth's surface separated into?

Answer 27

The Earth's surface is separated into huge plates of lithosphere that float on the underlying mantle

Question 28

To all of Earth's major topographic features on earth's surface arise from?

Answer 28

As a direct result of the motion and interactions of lithospheric plates

Question 29

What did Alfred Wegener hypothesize?

Answer 29

Wegner hypothesized the continental drift hypothesis. it included that the supercontinent, Pangaea, consisted of a northern landmass called Lauraisia and a southern landmass called Gondwana. As Pangaea broke up, the various continents moved to theirpresent-dayy locations

Question 30

What was the problem with Wagner's hypothesis?

Answer 30

Wegner could provide no mechanism to explain how the continents moved

Question 31

What is some of the most compelling evidence for continental drift?

Answer 31

Fossil evidence

Question 32

What are striations?

Answer 32

* Scratches or grooves on bedrock surface * by rocks moving in base of glacier ice * orientation shows direction of ice movement * especially useful for continental glaciers, where valleys did not control ice flow direction

Question 33

What revived the Continental Drift Hypothesis?

Answer 33

Polar wandering Although it did not not provide a mechanism explaining the movement.

Question 34

What is seafloor spreading?

Answer 34

Where the ocean crust moving laterally, splitting along the oceanic ridges

Question 35

How were the continents able to move?

Answer 35

Confirmation of the hypothesis of seafloor spreading explained that continents are carried passively along atop the fragments of lithosphere that carry seafloor crust away from the oceanic ridges.

Question 36

What is an example of a slow moving plate? Why does it move slowly?

Answer 36

An example of a slow-moving plate is the African plate. It moves slowly due to carrying a lot of continental crust

Question 37

What is an example of a rapidly moving plate? Why does it move rapidly?

Answer 37

The Pacific plate is an example of a rapidly moving plate. It moves rapidly due to no continental crust

Question 38

What is a hotspot? And what is an example of a hotspot?

Answer 38

A hot spot is where a source of magma is rooted in place. the Hawaiian Islands are an example of a hotspot, as plates move across the hotspot, new islands are formed one after another.

Question 39

What are the three basic types of plate boundaries?

Answer 39

The three basic types of plate boundaries are divergent, convergent, and transform.

Question 40

What are convergent plate margins?

Answer 40

* Where two plates move toward each other * destructive margins * occur between plates carrying either oceanic crust, continental crust or both

Question 41

Describe an ocean-ocean convergent margin.

Answer 41

* One plate will undergo subduction into the mantle beneath the other plate * this is called a subduction zone * which of the two converging oceanic plates will be subducted seems dependent upon the velocity and the angle of approach

Question 42

Describe an ocean-continent convergent margin.

Answer 42

* Continental crust is much less dense than oceanic crust * continental crust will ride up and over while the oceanic crust gets subducted beneath * also called subduction zone

Question 43

Describe a continent-continent convergent margin.

Answer 43

* Both plates are low-density and cannot undergo subduction, so they collide * form a continental collision zone * marks the final disappearance of an ocean basin, form spectacular mountain ranges

Question 44

describe a transform fault plate margin

Answer 44

* Where two plates slide past each other in a horizontal or strike-slip motion * can occur in oceanic or continental crust * conservative margins, where crust is neither created nor destroyed * the most famous example of such a boundary is the San Andreas Fault

Question 45

What type of boundary is the San Andreas Fault?

Answer 45

It is a transform fault plate margin

Question 46

Will provide explanations for the major topographic and geologic features we see on earth surface?

Answer 46

Plate tectonics provides explanations for both ocean basins and for continents

Question 47

What are the 5 major topographic features of ocean basins?

Answer 47

1. Mid Ocean Ridge 2. continental shelf 3. continental slope 4. continental rise 5. abyssal plains

Question 48

What formed the Himalayas?

Answer 48

Continent collision zones that form massive mountain chains