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Inside Earth
Chapter 1
Test Review Guide
Terms to define:
asthenosphere
Definition
lithosphere
radiation
conduction
convection
convergent
divergent
transform
plate tectonics
Pangaea
plates
subduction
sea-floor spreading
seismic waves
sonar
Earth’s Interior (Section 1.1):
1. Explain 2 ways that scientists know about the Earth’s interior.
a. Direct—rock samples/drilling samples
b. Indirect—seismic waves
2. What are seismic waves?
Tremors from earthquake
Hour ______
3. Compare (and contrast) lithosphere and asthenosphere.
Lithosphere
Both
Hard, rigid layer of the crust and the
upper mantle
Part of the upper mantle
Asthenosphere
Soft (flexible) plastic-like layer of the
upper mantle
Layer of the Earth
Solid rock
Bends like plastic or hot tar
Solid
Consider solid
4. Complete the following table.
Earth’s Layers from Outside In
Description of the Layer
Thin layer of rock; outermost layer
Crust
Thick layer of rock (some molten, but mostly solid); convection
currents occur here
Layer of liquid iron and nickel (metal); extremely hot; movement
causes Earth’s magnetic field
Layer of solid metal (nickel & iron); extremely hot; extreme
pressure keeps it solid; source of heat for convection
Mantle
Outer Core
Inner Core
Heat Transfer (Section 1.2):
5. Complete the following table.
Types of Heat Transfer
Conduction
Radiation
Convection
Definition
The transfer of heat between
materials that are touching
The transfer of heat energy through
space
The transfer of heat through the
movement of a fluid.
Example
Touching a hot pan or a metal
spoon in the pan, burning yourself
Feeling the warmth of the sun on
your skin.
Boiling water in a pan to make
macaroni
6. What would happen to convection currents if heat is no longer added (pg. 16)?
Convection currents would stop if heat is no longer added.
7. Explain how convection currents in the Earth’s mantle cause the plates to move on the Earth’s
surface (pg. 17).
Over millions of years, the great heat and pressure in the mantle cause solid rock to flow very
slowly. Plumes of mantle rock rise slowly form the bottom of the mantle toward the top. The hot
rock eventually cools and gravity makes it sink back through the mantle. Over and over, the cycle or
rising and sinking takes place. Geologists think that movement of convection currents causes plate
movement as the currents cause sea-floor spreading and push the older crust aside.
Continental Drift Hypothesis (Section 1.3):
8. State the continental drift hypothesis.
All the continents were once joined together in a single landmass and have since drifted apart.
9. Who thought of the continental drift hypothesis?
German scientist, Alfred Wegener (1910), published book, The Origin of Continents and Oceans (in
1915)
10. List three types of evidence that was gathered to support continental drift hypothesis.
a. Landforms—fit together like a puzzle…coal fields and mountains lined up
b. Fossils—fossils of tropical fernlike plants found on Antarctica (today very cold); fossils of
freshwater reptiles found on lands now separated by oceans
c. Climate—glacial scratches in Africa; fossils of tropical plants found on island in Arctic
Ocean
11. Why was the continental drift hypothesis rejected by scientists at first (pg. 22)?
Because Wegener could not explain how continents could move…he could not provide a satisfactory
explanation for the force that pushes and pulls continents.
Sea-Floor Spreading and Subduction (Section 1.4):
12. Complete the following table.
What is it?
Why does it
occur?
Where does it
occur?
Sea-Floor Spreading
The sea floor moves apart
Two plates are moving in the opposite
direction because molten material erupts
through a crack in the crust and cools to form
strips of solid rock
Along both sides of a mid-ocean ridge as new
crust is added
Subduction
Parts of the ocean floor sinking back into
the mantle
As ocean crust is push away from a midocean ridge toward a deep ocean trench,
part of the ocean floor sinks back into the
mantle
At deep underwater canyons called deepocean trenches
13. What new technology was invented that allowed scientists to map the ocean floor in the mid 1900s
and subsequently discover that sea-floor spreading was occurring in the Atlantic Ocean?
Sonar
14. What “evidence” was gathered to support Harry Hess’s theory of sea-floor spreading?
a. Molten material—pillow rocks formed from harden magma shaped like pillows or like
toothpaste squeezed from a tube
b. Magnetic Stripes—harden rock in ocean floor containing iron shows that Earth’s magnetic
poles have switch several times in Earth’s history
c. Drilling samples—rocks from drilling samples show that the youngest rocks were always in
the center of the ridges…the farther away, the older the rocks get.
15. How does the age of rock close to the mid-ocean ridge compare with rock close to the continents?
Rocks close to the mid-ocean ridge are very “young,” while rocks at the edge of oceans/continents
are older.
Plate Tectonics (Section 1.5):
16. What does the Theory of Plate Tectonics state?
The Theory of Plate Tectonics states that pieces of Earth’s lithosphere are in slow, constant
motion, driven by convection currents in the mantle.
17. Complete the following table.
Type of Plate Boundary
Convergent Boundary
Movement of Plates
Landforms Created at
Boundary
Plates move towards each
other—collide—come
together
On continents:
_____mountains______________
(sometimes volcanoes)
In Oceans:
__deep-ocean trench___
Divergent Boundary
Plates move away from
each other—rifting or
sea-floor spreading occurs
On continents:
__rift valley_______________
In Oceans:
__mid-ocean trench_
Transform Boundary
Plates slide past each
other side by side
Faults, frequent small
earthquakes
Examples on Earth
Himalayas (India/Asia)
Mariana Trench
(near Japan)
African Rift Valley
Mid-Atlantic Ocean
Ridge
__San Andreas Fault __
(in California)
18. How does sea-floor spreading cause subduction?
As ocean crust is pushed away from a mid-ocean ridge the sea-floor spreads out toward a deep ocean
trench where part of the ocean floor sinks back into the mantle.
19. According to the Theory of Plate Tectonics, describe how the Himalayan Mountains may have
formed.
According to the Theory of Plate Tectonics, the Himalayan Mountains formed when two continental
plates collided. India is on one plate moving north. India is lighter and faster moving than the plate
carrying Asia. When India caught up to Asia and collided with it, the collision squeezed the crust
into the mighty Himalayan Mountains.
20. Name the plate boundaries at X, Y, and Z and describe the process that occurs at each boundary in
the diagram below.
X=divergent boundary=sea-floor spreading=mid-ocean ridge
Y=convergent boundary=collision/subduction/deep-ocean trench=mountains &/or volcanoes
Z=convergent boundary=subduction=deep-ocean trench