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
23.
According to the passage, what ███████ ████ ███ ██████ ██████ ██ ███ ████ █████████ ████████
a
The trailing edge ██ ███ █████████████ █████ ██ █████████ █████ ███ █████████████ ██████
The leading edge of the faster-moving plate is subducted under the trailing edge of the slower plate. So the trailing edge of the slower plate isn’t subducted under faster plate.
b
The leading edge ██ ███ █████████████ █████ ██ █████████ █████ ███ █████████████ ██████
The leading edge of the faster-moving plate is subducted under the trailing edge of the slower plate. The leading edge of the slower-moving plate isn’t subducted under anything.
c
The trailing edge ██ ███ █████████████ █████ ██ █████████ █████ ███ █████████████ ██████
The leading edge of the faster-moving plate is subducted under the trailing edge. It’s not the trailing edge of the faster plate that’s subducted; it’s the leading edge of that plate.
d
The leading edge ██ ███ █████████████ █████ ██ █████████ █████ ███ █████████████ ██████
e
The leading edge ██ ███ ███████ █████ ██ █████████ █████ ███ ██████ ██████
The author doesn’t discuss smaller vs. larger plates. What matters is what’s faster-moving and slower-moving.