#
8
Plate
#
Term
Description
Place the # from the Description
nextantooceanic
the correct
1
thecolumn
zone where
plate isTerm.
sinking
below a plate containing continents at a
converging plate boundary
the process by which rocks move past one
another along a fracture or cracking the earth’s
crust, usually occurring where plates are
separating, sliding past one another, or
colliding
4
Asthenosphere
2
13
Tectonics
3
21
Lithosphere
4
11
Folding
5
2
Faulting
6
A fault where two sections of the earth’s crust
move almost horizontally past each other
9
Hot Spot
7
the boundary between two plates that are
moving apart or separating, at a mid-ocean
ridge
12
Converging plate boundary
8
7
Diverging plate boundary
9
a rigid slab of solid lithosphere rock that has
defined boundaries and floats on the denser
rocks of the asthenosphere
a point on the earth’s surface where strong
upward convection currents or plumes of hot
magma in the upper mantle push up below the
plates of the lithosphere causing volcanic
activity
3
Transform plate boundary
10
A block of hard rock left standing above the
landscape when an extinct composite volcano is
eroded away over millions of years.
1
Subduction zone
11
19
Sea-floor spreading
12
16
Viscosity
13
17
Transform Faults
14
the process that bends and twists rocks through
compression or squeezing
the boundary between two plates that are
moving towards one another
the processes that deform the earth’s
lithosphere and the rock structures and surface
features created by these processes
The downward movement and eventual melting
of an oceanic plate as it sinks into the
asthenosphere along converging plate
boundaries
3
Fault Scarps
15
Rock beds that have been folded or bent
downwards to form a valley
6
Strike-slip Faults
16
The resistance to flow of a liquid, such as
the boundary between two plates that are
slipping or sliding past one another
the plastic (part solid, part liquid) layer of the
upper mantle directly below the lithosphere that
can flow slowly when put under constant
pressure.
The often straight, continuous cliff created by
the uplift of the earth’s crust along a fault line
magma or molten rock
14
Subduction
17
A fault formed by the horizontal movement of
the earth’s crust, occurring where two plates are
sliding past one another
10
Volcanic Necks
18
Rock beds that have been folded or bent
upwards to form a hill or mountain
20
Composite Volcanoes
19
The process that creates new sea floor as plates
spread apart or separate at mid-ocean ridges
18
Anticlines
20
A smooth-sloped volcanic peak with a summit
crater made up of alternating layers of ash and
lava, formed from andesitic magma at
subduction zones
15
Synclines
21
the solid outer layer of the earth where the
rocks are less dense and more rigid than those
of the asthenosphere below; includes the top
part of the mantle and all of the crust.
1. What sets the continental plates in motion? Describe the process. (1 mark)
Convention currents (heat rising) in the asthenosphere expand and migrate to the surface while
cooler material flows to fill the void.
2. Briefly explain the difference between Converging, Diverging and Transform
Fault boundaries. (3 marks)
Converging…plates moving together (collide or slide under the other)
Diverging….plates separate from each other
Transform Fault….plates slide past each other
3. Give 1 evidence of sea-floor spreading that scientists have? (1 mark)
A pattern of magnetic variations on either side of the ridge revealed a striped pattern that was
parallel. The pattern also showed a mirror image on both sides of the ridge.
A second discovery of magnetic reversals of rock on either side of the ridge. The
farther from the ridge, the older the rock. Scientists learned that over time, the
magnetic polarity of rock changes or reverses from north to south and back.
4. Give 2 reasons why diverging tectonics are less violent than converging
tectonics? (2 marks)
The lithosphere is thinnest near the mid-ocean ridges
The plates are spitting apart, allowing hot magma from the upper mantle to move easily toward the
earth’s surface
The low viscosity of the magma
5. What causes the narrow valleys along a fault line? (1 mark)
As the plates slide past one another, the pressures shatter the rocks along the fault line. The
shattered rocks are eroded to create the valley.
6. What is fault creep? (1 mark)
Short movements along the fault that gradually release pressure. This creep an release of pressure
means earthquakes are lower in magnitude and less destructive.
7. Explain what it means when the plates are locked. What is the result then? (1
mark)
Where the rock surfaces are rough, the plates get stuck on each other. The pressure continues to
build up eventually to be released as an earthquake. The longer the pressure builds, the stronger
and more destructive the earthquake.
8. How do laser sensors, seismographs and strain gauges help scientists detect and
predict earthquakes? (1 mark)
By measuring the movement of the earth they can determine if the fault plates are locked or
creeping steadily and also measure the amount of movement of the plates. This will help them
generate their predictions.
9. What are the two types of converging plate boundaries? (2 marks)
Subduction zones (where an oceanic plate is slipping below a continental plate)
Collision zones (where two continental plates are meeting)
10. Describe how it is possible for one plate of rock to descend beneath another. Ie,
what are the elements necessary to allow that to happen? (1 mark)
-thin ocean plates with heavy basaltic rock descent into the plastic asthenosphere beneath lighter, thicker
granitic rocks of continental plates
-Descending plates are cooler so they sink down. That is subduction.
11. Briefly describe what happens when two plates collide and neither of those plates
is able to descend beneath the other? (1 mark)
-two continental plates collide
-rocks of the continental plates are lighter and less dense than those of the asthenosphere…don’t sink
-rocks collide to create massive mountain ranges of twisted rocks (Himalayas, Appalachian, Alps)
12. Explain why some volcanoes are more spectacular and destructive than others. (1
mark)
Cooler materials of the andesitic magmas, with silica and gases, tend to clog up the vents of volcanies
leading to the build up of pressure. When the pressure becomes great enough, a major explosion hurls
magma onto the earth’s surface and into the atmosphere.
13. What is the difference between continental volcanic arcs and island arcs? (1 mark)
Same thing, but the only difference is where the arcs are found. Continental arcs are located in
continents while island arcs are formed from volcanoes build on the ocean floor.
14. Scientists speculate ocean floor rock is much younger that continental rocks. Why
would ocean floor rocks be younger? (1 mark)
Because of the subduction. The rocks at subduction zones are consumed as they migrate to the
ansthenosphere. Continental rocks on the other hand are lighter and are not consumed at
subduction zones, allowing them to stick around much longer.
15. Cratons are described as the roots of mountains. Explain. (1 mark)
They are actually what is left from millions of years of erosion, so they are called the roots of the
mountains.
16. Briefly describe 2 processes of accretion. (2 marks)
The edges of continents are often plate boundaries and are active zones of mountain building. This
is one way continents increase in size.
Another way they increase in size is through erosion of the mountains, depositing eroded material at
the edge of the continent.