Download Background Knowledge – Layers of the Earth 1. List the layers of the

Name: KEY
Unit III: The Lithosphere – Section 2 Volcanic Thermal Processes
Earth & Environmental Systems Science
Volcanic Processes Study Guide
Background Knowledge – Layers of the Earth
1. List the layers of the Earth starting and the surface and describe if they are
solid or liquid in state.
Continental Crust/Lithosphere - solid
Oceanic Crust/Lithosphere - solid
Mantle/Asthenosphere - liquid
Outer Core - liquid
Inner Core - solid
2. What data do we measure in order to determine the thickness of the layers?
We use seismic data and can measure the speed and timing of the
earthquakes in order to calculate the distance or thickness of the layers.
3. The plates of solid lithosphere ride on top of the asthenosphere.
4. Fill out the following chart:
Type of
Density
Thick/Thin
Type of Rock
Lithosphere:
Continental Crust Low density due to Thick
Granite
high volume
High density due to Thin
Oceanic Crust
Basalt
low volume
Thermal Process – Convection
1. The movement of tectonic plates is driven by what thermal process in the
mantle? Tectonic plates including continental and oceanic crust move due to
convection currents in the mantle that transfer heat from the outer core to the
mantle and then to the crust.
2. Define the term convection: Convection is a mixing due to unevening heating
that causes a difference in the temperature and density of the material that
makes a rising or sinking motion of the fluid.
3. True or False: Changes in the mantle material’s heat and density is causes
convection currents.
4. How does a lava lamp represent convection currents in the mantle? The light
bulb heats the material unevenly just like the outer core heats the mantle
unevenly. As the temperature rises, the volume expends, creating a material
that has a low density and a rising effect. As the material moves away from
the heat source, it cools, condenses, and sinks.
Location of Volcanic Activity
1. At a divergent plate boundary, volcanoes form along which feature on the
ocean floor? Mid-Ocean Ridge (Rise)
2. What is an underwater mountain chain called? Ocean Ridge
3. At a mid-ocean ridge, where would the hottest crust temperature be located?
At the center of the mid-ocean ridge where mantle material is cooling to form
new crust.
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Name: KEY
Unit III: The Lithosphere – Section 2 Volcanic Thermal Processes
Earth & Environmental Systems Science
Volcanic Processes Study Guide
4. Describe the trends of the ocean floor age, sediment thickness, and heat flow as
you move away from the center of the mid-ocean ridge. As you move away from the
center of a mid-ocean ridge, the ocean floor gets older, the sediment on top of the floor
gets thicker, and the heat flow decreases or gets colder proving that the center of the
Mid-Ocean Ridge is the location of newly formed oceanic crust due to mantle
convection currents.
5. What is one similarity and one difference between a rift valley and a mid-ocean
ridge? Rift Valleys and Mid-Ocean Ridges are locations where the crust is spreading
apart due to mantle convection currents and new crust is being formed. Rift Valleys
are tearing continents apart and may be covered by a small inlet and a sea. MidOcean Ridges are tearing oceanic crust apart to make new oceanic crust and are
covered by vast oceans.
6. Why does oceanic crust sink beneath the continental crust at subduction zones?
Oceanic crust is more dense than continental crust and will sink or be over-ridden by
the continental crust. The oceanic crust is melted and recycled back into the mantle.
7. Compare the plate motion at a trench to the plate motion at a mid-ocean ridge. At a
mid ocean ridge, oceanic crust is moving outward to make new oceanic crust. At a
trench a collision occurs where oceanic crust is being subducted by continental crust,
and the oceanic crust is melted an recycled back into the mantle.
8. Draw in the convection currents based on the features of the mid-ocean ridge and
trench:
9.
What feature is formed when a piece of continental crust and a piece of oceanic
crust collide?
The oceanic crust will be subducted because it is more dense. When the plates
collide, friction creates a pulling effect on both pieces of crust and a deep oceanic
trench is formed.
10. What feature is formed when two pieces of oceanic crust collide? One piece of
oceanic crust will be subducted. When the plates collide, friction causes the
subducting plate to melt quickly, becoming less dense and sending magma upward.
This magma cools and solidifies as a volcanic island arc.
11. Describe how hot spot volcanoes create and chain of islands on how that can
predict plate movement. The small hot spot stays stationary (at the same latitude
and longitude) and creates a shield volcano as the magma breaks through the thin
oceanic crust. This process continues to create a larger and larger volcano. The plate
moves and will take the volcano with it, eventually moving it
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