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Physical Geology Learning Objectives and Study Questions
Chapter 2: Tarbuck and Lutgens 12e
1. Cite three independent lines of evidence that support the continental drift hypothesis and describe
the hypothesis’ major weakness.
2. Distinguish between the three types of plate boundaries based on the relative motions of the
lithosphere plates across them and the general patterns of seismicity, volcanism, crustal age and
elevation along them.
3. Referring to a map of an oceanic ridge and its flanking magnetic anomalies that are offset by a
transform fault, determine the sense of offset on the transform and the rate of spreading at the
ridge.
4. Draw a series of simple, well-labeled maps that illustrate how an elongate ocean basin and a
flanking “failed rift” develop during an episode of continental rifting.
5. Working from a map showing the locations and ages of a series of volcanoes formed above a
hotspot, determine the speed and general direction of the plate the volcanoes are built on.
6. Briefly describe the origins of the major plate driving forces and indicate which one is thought to
play the largest role.
1. Wegener’s continental drift hypothesis was not widely accepted because it could not account for
_____.
A. locations of mountain ranges and mineral deposits
B. the mechanism of continental movement
C. distributions of glacial deposits on southern continents
D. distributions of fossil organisms
E. the geographic fit of the continental margins
2. Subduction zones, like the Cascadia subduction zone here in the Pacific Northwest, always mark
_____ plate boundaries.
A. divergent
B. convergent
C. inactive
D. passive
E. shear
3. Continental rift systems, like that in East Africa, are the early stages of _____ plate boundaries.
A. divergent
B. convergent
C. indeterminate, too soon to tell
D. passive
E. shear
4. The San Andreas Fault is a classic example of which type of
plate boundary?
A. divergent
B. convergent
C. inactive
D. passive
E. shear
5. Continental rift systems initially develop _____ arms, of which
_____ typically grow(s) to become an ocean basin.
A. 2, 1
B. 3, 1
C. 3, 2
D. 4, 1
E. 4, 2
6. The transform fault shown as a bold line in the accompanying
map displays _____ offset.
A. normal
B. reverse
C. right-lateral
D. left-lateral
E. essentially no
7. Extending out along the trend of the transform fault on either
side are _____.
A. mid-ocean ridges
B. magnetic anomalies
C. transcurrent faults
D. fracture zones
E. hotspot tracks
8. The mystery of how continents “drifted” was eventually resolved by Vine and Matthews’ discovery
of _____.
A. magnetic reversals
B. radiometric dating
C. stratigraphic correlation
D. seafloor spreading
E. plate tectonics
9. Geomagnetic reversals, when Earth’s north and south magnetic poles “flip”, occur_____.
A. every few years
B. every few million years
C. every billion years or so
D. on a predictable schedule
E. more or less randomly in geologic time
10. Apparent polar wander paths for different continents align with one another after _____.
A. these continents are sutured together
B. these continents rift apart
C. subsequent reversals reset the magnetic record
D. periods of no more than a few centuries
E. the stars align correctly
11. The Yellowstone hotspot currently lies in northwest
Wyoming, and the Snake River Plain is its “track”. Based on
this, which way is North America moving?
A. northeast
B. northwest
C. southeast
D. southwest
E. indeterminate cannot tell from the map
12. During the past 13 million years, North America has moved about 650 km relative to the underlying
hotspot. What is the average rate of plate motion?
A. 2 km/Ma
B. 5 km/Ma
C. 20 km/Ma
D. 50 km/Ma
E. 200 km/Ma
13. Which of the following forces appears to play the largest role in driving plate motion?
A. mantle drag
B. magnetic induction
C. slab pull
D. lunar gravity
E. ridge push