Chapter 2

Question 1

What did Alfred Wegener proposed?

Answer 1

• He proposed the “continental drift” hypothesis in 1912
• Pangaea (270-200 ma)
• Panthalassa

Question 2

The evidence for continental drift included:

Answer 2

• the puzzle-like fit of the continents
• fossils
• Mountain Ranges
• Glacial Striations and Till

Question 3

Why was continental drift rejected?

Answer 3

• because Wegener’s proposed mechanism of continental movement didn’t work
• lacked explanation for the cost of continental drift.
• Wegener believed that continental drift was the result of centrifugal force and tidal attraction, but the scientific community found the argument weak.

Question 4

What were the results of seafloor mapping and drilling after WWII?

Answer 4

• Seafloor Spreading hypothesis.
• Mid-Ocean Ridges (MORs)
• symmetrical patterns of magnetism in seafloor rocks
• symmetrical patterns of rock ages on the seafloor
• increasing thickness of seafloor sediments
• Hot Spot Volcanoes

Question 5

The ___________ says the earth’s surface is divided into large, puzzle-like pieces called________.

Answer 5

• Theory of Plate Tectonics

- Tectonic Plates

Question 6

What are plates made of?

Answer 6

• Oceanic Crust
• Continental Crust
• Upper Mantle (lithosphere)
• Granite
• Basalt
• Peridotite

Question 7

Where do plates “float” and “move”

Answer 7

Asthenosphere

Question 8

Plate movement is related to _______ and _________.

Answer 8

• Mantle Convection

- Slab-Pull

Question 9

Where are earthquakes and volcanoes located?

Answer 9

Plate Boundaries

Question 10

What are the three types of Plate Boundaries?

Answer 10

1. Divergent Plate Boundaries- result of seafloor spreading and form Mid-Ocean Ridges and Rift Valleys
2. Transform Plate Boundaries - transform faults that cut across divergent plate boundaries. San Andreas Fault
3. Convergent Plate Boundaries - Subduction, Trenches, Volcanic Arcs, or Complex Mountain Ranges

Question 11

Ocean to Continent Convergence

Answer 11

Produces “Continental Volcanic Arcs”

Question 12

Ocean to Ocean Convergence

Answer 12

Produces “Volcanic Island Arcs” (Japan)

Question 13

Continent to Continent Convergence

Answer 13

Produces “Complex Mountain Chains”

Question 14

The supercontinent ______ existed between 750 million and 1.1 Billion years ago

Answer 14

Rodinia

Question 15

_____ could occur within the next 250 million years

Answer 15

Pangaea Ultima

also called Pangaea Proxima, Neopangaea, and Pangaea II

Question 16

1) Which of the following was not used as evidence for continental drift?
a. The fit of the continents
b. Matching sequences of rocks
c. Past glacial activity
d. The distribution of organisms
e. Paleomagnetic Reversals

Answer 16

Paleomagnetic reversals

Question 17

2) All continents fit together with the least number of overlaps and gaps when the continents are matched along\_\_\_\_\_\_.
A) edges at around 2,000 meters depth
B) current shorelines
C) the edge of the continental shelf
D) edges of the deep sea floor
E) oceanic trenches in subduction zones

Answer 17

Edges at around 2,000 meters depth

Question 18

3) The seafloor magnetic pattern is best described as ________.
A) not related to the location of mid-ocean ridges
B) parallel to and symmetric about mid-ocean ridges
C) parallel to, but not symmetric about mid-ocean ridges
D) perpendicular to and symmetric about mid-ocean ridges
E) perpendicular to, but not symmetric about mid-ocean ridges

Answer 18

Parallel to and symmetric about mid-ocean ridges

Question 19

4) Which of the following fossils was used as data to help reconstruct Pangea because it was a reptile found in South America and Africa?
A) Lepidodendron
B) Archaeopteris
C) Glossopteris
D) Mesosauras
E) All of the above

Answer 19

Mesosauras

Question 20

5) Tectonic plates move about as fast as \_\_\_\_\_\_\_\_.
A) a child crawls
B) a river flows
C) a snail crawls
D) grass grows in the summer
E) your fingernails grow

Answer 20

Your fingernails grow

Question 21

6) Which of the following is the most convincing piece of evidence set forth to support the concept of sea floor spreading?
A) The correlation of rocks found in adjacent positions on matching continents.
B) The mid-ocean ridge is entirely volcanic in origin.
C) The mid-ocean ridge rises more than 2.5 kilometers above the surrounding deep-ocean floor.
D) The oceanic pattern of alternating reversals of Earth’s magnetic field.
E) None of the above

Answer 21

???????The oceanic pattern of alternating reversals of Earth’s magnetic field.

Question 22

7) Based on the Theory of Plate Tectonics, you would expect to find \_\_\_\_\_\_\_\_ heat flow at the mid-ocean ridge and \_\_\_\_\_\_\_\_ heat flow at subduction zones when compared to other parts of the crust.
A) decreased; decreased
B) decreased; increased
C) increased; decreased
D) increased; increased
E) None of the above are correct

Answer 22

Increased; Decreased

Question 23

8) The Gulf of California is an example of \_\_\_\_\_\_\_\_ plate boundary.
A) a continental-continental convergent
B) a continental-continental divergent
C) an oceanic-continental convergent
D) an oceanic-oceanic convergent
E) an oceanic-oceanic divergent

Answer 23

A continental-continental divergent

Question 24

9) The Mariana Trench is an example of \_\_\_\_\_\_\_\_ plate boundary.
A) a continental transform
B) an oceanic transform
C) an oceanic-continental convergent
D) an oceanic-oceanic convergent
E) an oceanic-oceanic divergent

Answer 24

An oceanic oceanic convergent

Question 25

Students sometimes ask…What changes to Earth’s environment would occur when the magnetic poles reverse?

Answer 25

• incorrect directions and difficulty navigating
• fish, birds, and mammals, that sense magnetic field during migrations
• reduce protections that for life-forms against cosmic rays and particles coming from the sun
• Disrupts low-Earth-orbiting satellites as well as some communication and power grid systems.
• Aurora Borealis (Northern lights) and counterpart Aurora Australis (Southern lights) which are natural light display, might be visible at lower latitude
• Earth has successfully survived previous magnetic reversals.

Question 26

Students sometimes ask…When will California fall off into the ocean?

Answer 26

• Earthquakes occur as the Pacific Plate continues to move to the northwest past the North American Plate, at a rate of about 5 centimeters (2 inches) a year.
• Los Angeles will be adjacent to San Francisco in just over 12 million years.
• CALIFORNIA WILL NEVER FALL INTO THE OCEAN
• people living near this fault should be very aware they are likely to experience a large earthquake within their lifetime.

Question 27

Students sometimes ask…How long has plate tectonics been operating on Earth? Will it ever stop?

Answer 27

• Plate tectonics has been operating for at least the past 3.8 billion years of Earth History.
• active and continuous process w/ new seafloor constantly being formed while old sea floor is being destroyed.
• plates may move, then slow down or event stop and start up again. The reason for this intermittent plate motion appear to be related to plate distribution and changes in the amount of heat released form Earth.
• forces that drive plates will likely decrease until plates no longer move.
• powered by heat released from within Earth (which is of a finite amount.