Self-study
P1
According to the generally accepted theory of plate tectonics, the earth's crust consists of a dozen or so plates of solid rock moving across the mantle—the slightly fluid layer of rock between crust and core. ████ ███████████ ███ ████ ██ █████████ ██ █ ██████ ██ ███ ████████ ██ █████ ██████ ███████ ███ ███████ ██ ████ ████████ ███
Phenomenon & hypothesis ·
Earthquakes explained by plates colliding
Details of hypothesis ·
Collision causes subduction which causes earthquakes
Explains seismic hot zones: high levels of subduction produce many earthquakes
Phenomenon ·
But subduction can also occur without causing earthquakes
P2
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Hypothesis ·
Type of collision makes a difference
Collision type 1 ·
Plates moving toward each other
Occurs in seismic hot zones (many earthquakes)
Collision type 2 ·
Plates moving in same direction
Occurs in quiet zones (few earthquakes)
Analogy ·
Collision type 2 behaves like boat's oar
Collision zone moving across mantle (fluid layer) like boat over water; subducting plate descends steeply into mantle like oar in water
Evidence for hypothesis ·
Collision type 2 involves little contact (friction) between plates
Less friction means less likely to cause earthquake
Evidence for hypothesis ·
Collision type 1 involves more contact (friction) between plates
Collision zone not moving across mantle, so colliding plates remain in contact with each other. More friction means more likely to cause earthquake.
Analogy ·
Collision type 1 behaves like sheets of sandpaper
Colliding plates slide across each other; high resistance (friction)
P3
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Implication ·
of hypothesis
Regions with little subduction (plate collision) could still cause earthquakes, depending on collision type (collision type 1 causes greater risk)
Passage Style
Phenomenon-hypothesis (RC)
Single position
22.
Which one of the following ████ ██████████ █████████ ███ ████ █████ ██ ███ ████████
a
As a result ██ ███████████ ██ ██████████ ████ █████████ ██████ ███ ██████ ██ ███ ████ ██ ██ ████████ ███████████ ███ ██████ ██ ██████████ ██ █ ██████ ██ ████████ ██████████ ████ ███ ██████ ██ ████████████
This doesn’t capture the author’s focus on a particular phenemonon and the explanation for that phenomenon. The phenomenon is regions with high subduction, but few earthquakes. What explains this? The author focuses on a hypothesis to explain that specific phenomenon. (A) doesn’t capture this. In addition, (A) is unsupported, because the author suggests that direction of plate collision is an important factor in earthquake frequency. Subduction amount alone wouldn’t be a good sign of the number of earthquakes.
b
The differences between ███ █████████ ██████ ████████ ████ ██████ ██ ███ ████ ██ ██ ████████ ██████████ █████ ██████████ █ █████████ ███████████ ██ ███ ██████ ██ ███████████ ██ ████ ███████ ██ ███████ ███████████
This best captures the author’s point, which is that a group of scientists believe the direction of plate collission can explain why there are high subduction zones with few earthquakes. The author presents this hypothesis at the beginning of P2 and describes how it works in the rest of P2.
c
Some scientists theorize ████ ███████ ██████ ██████ ████ ██████ ██ ███████████ █████ █████ ██████ ███ █████████ ██ ███ ████ █████████ ████ █████████████ ██ ███ ███████ ████ ████ ██████
Not supported, because the hypothesis is that certain zones might have high subduction but few earthquakes due to the direction of the plates when they collide. The hypothesis does not suggest that lack of earthquakes is due to lack of plate collision. Because (C) gets the hypothesis wrong, it can’t be the main point.
d
A new version ██ ███ ██████ ██ █████ █████████ ████ ████████ ███ █████████ ████████ ███████████ ██ ███████████ ██ █████████ ████ ███ ███████ ██ ██████████ ███ ████ ███████ ██ ████ ███████████
Not supported, becaue the hypothesis presented by the author doesn’t abandon the explanation that earthquakes result from subduction. Rather, it adds a complicating factor to this explanation — direction of collection matters. Since (D) gets the hypothesis wrong, it can’t be the main point.
e
The generally accepted ██████ ██ █████ █████████ ██ ██████████ ██ ███ ████████ ████ █████ ███ ███████ ██ ███ █████ ████ ████ ██████ ██ ██████████ ███ ██████ █████████████ ████ ██████████ ███ ██████ ██ ███████ █████████
This doesn’t capture the author’s presentation of a hypothesis to explain the regions with high subduction and earthquakes. In addition, the author never suggests that the theory of plate tectonics is threatened; it may be complicated by the addition of direction of plate collision as a factor in earthquakes, but that doesn’t mean the theory is threatened.