Chapter 9 Plate Tectonics Flashcards
Wegener’s continental drift hypothesis stated that all the
continents once joined together to form
a. two major supercontinents.
b. two major supercontinents and three smaller continents.
c. one major supercontinent.
d. three major supercontinents.
c. one major supercontinent.
The hypothesis of continental drift is used to explain an event that happened a. two million years ago. b. two hundred million years ago. c. two billion years ago. d. two hundred billion years ago.
b. two hundred million years ago.
What evidence supports Wegener’s hypothesis?
a. The same mammal species exist on different continents.
b. Major rivers on different continents match.
c. Land bridges still exist that connect major continents.
d. Fossils of the same organism have been found on different continents.
d. Fossils of the same organism have been found on different continents.
Evidence about ancient climates indicates that
a. glacial ice once covered much of what is now India and Australia.
b. the countries found in the Northern Hemisphere today were once centered over the South Pole.
c. no continents occupied the Northern Hemisphere.
d. the countries found in the Southern Hemisphere today were once centered over the North Pole.
a. glacial ice once covered much of what is now India and Australia.
Which of the following results when divergence occurs within the oceanic lithosphere? a. seafloor spreading b. a rift valley c. a volcano chain d. a mountain range
a. seafloor spreading
What forms when one oceanic plate is forced beneath another plate? a. an ocean basin b. ocean ridges c. a subduction zone d. a rift valley
c. a subduction zone
Which of the following does NOT occur at a subduction
zone?
a. The leading edges of both plates are bent downward.
b. Oceanic crust is pushed down into the mantle.
c. One oceanic plate moves into another oceanic plate.
d. One continental plate moves into an oceanic plate.
a. The leading edges of both plates are bent downward.
Which of the following is NOT evidence of sea-floor
spreading?
a. the alternation of polarity in segments of the ocean floor
b. the relationship between earthquakes and plate boundaries
c. analysis of seafloor sediments
d. the distribution of ice sheets across the planet
d. the distribution of ice sheets across the planet
Which of the following is true of a rock that has the property
of paleomagnetism?
a. Rocks formed millions of years ago show the location of the magnetic poles at the time of their formation.
b. All rocks, regardless of when they are formed, will eventually possess the same polarity.
c. A major shift in polarity occurred in all rocks that were formed one million years ago.
d. A rock possesses a specific polarity depending on where it is formed.
a. Rocks formed millions of years ago show the location of the magnetic poles at the time of their formation.
- According to the theory of plate tectonics, the
a. asthenosphere is divided into plates.
b. lithosphere is divided into plates.
c. asthenosphere moves over the lithosphere.
d. asthenosphere is strong and rigid.
b. lithosphere is divided into plates.
What is the average movement of lithospheric plates?
a. 5 in. per year
b. 50 in. per year
c. 5 cm per year
d. 50 cm per year
c. 5 cm per year
What kind of plate boundary occurs where two plates grind
past each other without destroying the lithosphere?
a. divergent boundary
b. convergent boundary
c. transform fault boundary
d. transitional boundary
c. transform fault boundary
Which of the following is a geographic example of a tranform fault boundry? a. the East African Rift valley b. the Mid-Atlantic Ridge c. the San Andreas Fault d. the Mariana Arc
c. the San Andreas Fault
A divergent boundary at two continental plates can result in a(n)
a. mountain range.
b. rift valley.
c. island arc.
d. volcanic arc.
b. rift valley.
A convergent boundary occurs where
a. the Red Sea and Africa meet.
b. India and Asia meet.
c. the North American plate meets the Pacific plate.
d. the United States meets Canada.
b. India and Asia meet.
The islands of Java and Sumatra in Indonesia are an example of
a. a rift zone.
b. a hot spot.
c. an ocean ridge.
d. a volcanic island arc.
d. a volcanic island arc.
What is the main source of downward convection movement in the mantle?
a. ridge-pull
b. ridge-push
c. slab-push
d. slab-pull
d. slab-pull
The downward sliding characteristic of ridge-push is the result of
a. uneven heat distribution.
b. paleomagnetism.
c. gravity.
d. seafloor spreading.
c. gravity.
According to the whole-mantle model of mantle convection,
a. small amounts of material from the mantle move upward to the surface.
b. slabs of cold oceanic crust move down and into the lower mantle.
c. large chunks of continental crust are pulled down into the lower mantle.
d. material from the core-mantle boundary rises into the mantle to form mantle plumes.
d. material from the core-mantle boundary rises into the mantle to form mantle plumes.
What causes the thermal convection that drives plate
motion?
a. seafloor spreading
b. differences in temperature and density
c. gravity
d. subduction
b. differences in temperature and density
Alfred Wegener hypothesized that __________ was broken apart by the process of continental drift.
Pangaea
Wegener first began to think about his continental drift hypothesis when he noticed a similarity in __________ on different
continents.
coastlines
One type of evidence that supports Wegener’s continental drift hypothesis is the existence of __________ that begin on
one continent and continue on another.
mountain belts
Layers of __________ found in Africa, South America, India, and Australia help to support the continental drift hypothesis.
glacial till
Slab-pull occurs because oceanic crust sinks into the __________
asthenosphere
