Download Earth`s Crust in Motion – Study Guide

Name: ______________________________
Period: ______
Earth’s Crust in Motion – Study Guide
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Re-read Chapter 9 and know your vocab words!
Study all worksheets, quizzes, and the Guided Reading.
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Convection currents – layer / importance / why they occur
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The layer that convection currents occur is the mantle
o
Heat from the core and the mantle itself causes convection currents in the mantle.
o
Why are they important? Convection currents are important because without them, the
earth’s lithosphere would not move. No new land would be formed.
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The heated materials of the Asthenosphere become less dense and rise while cooler material
becomes denser and sinks.
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Then, gravity pulls the cooler, denser material back down, closer to the heat source, where it is then heated
again.
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Convection is caused by the difference of temperature & density in a fluid (hotter = less dense)
Heat Transfer
o The movement of energy from a warmer object to a cooler object is called heat transfer.
o
There are three types of heat transfer:
The transfer of energy through empty space is called radiation.
Heat transfer within a material or between materials that are touching is called conduction.
The transfer of heat by the movement of currents within a fluid is called convection.
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Continental drift
o What is it? Wegener’s idea that the continents slowly moved over Earth’s surface.
o
Who stated the theory? Alfred Wegener
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Why wasn’t it accepted early on? He couldn’t explain the force that pushes or pulls the
continents (how or why the continents moved)
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What evidence is used to support it today? Landforms, fossils, climate, pieces of a puzzle
Science 8- Earth’s Crust in Motion
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The relationship between temperature, density, and pressure
o Heat transfer by convection is caused by differences in temperature and density within a fluid.
o
When a liquid or gas is heated, the particles move faster. As they move faster, they spread
apart. Because the particles of the heated fluid are farther apart, they occupy more space. The
fluid's density decreases.
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3 types of boundaries—be able to recognize pictures, and describe what happens at each
o Name what type of boundary each picture is representing. Include the type of crust involved
in all convergent boundaries.
o Be able to describe what happens at each boundary.
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Divergent –plates move away from each other
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either land/land boundary OR ocean/ocean boundary
Land/land - creates rift valley
Ocean/ocean boundary - creates sea floor spreading (new ocean floor crust)
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Convergent— plates move toward each other
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Occurs at land/ocean or ocean/ocean boundaries
Denser plate goes on the bottom
Subduction is occurring
Creates volcanoes
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Convergent— plates move toward each other
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Continental (land) / land boundary
Creates mountains
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Transform— plates sliding past each other
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Causes earthquakes
Releases stored energy
Page 342 – 343: be able to recognize:
o Oceanic & continental crust
o The ocean and the continents
o Mid-ocean ridge
o Deep-ocean trench
o
o
o
The process of sea-floor spreading
Rift valley
What is the picture a representation
of?
Science 8- Earth’s Crust in Motion
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Label the Sea-floor spreading diagram from notes –the parts and the processes
A&B
C
D&E
F
G
H
I
J
K
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ocean crust—plates located in the ocean; more dense than continental plates
magma—molten material comes to the surface during sea floor spreading
ocean floor—the closer it is to the mid-ocean ridge, the newer it is
subduction—ocean floor sinks beneath a deep ocean trench and back into the mantle
land—above the ocean; earth’s crustal plates
mid-ocean ridge—under water ocean chain where new ocean floor is produced
sea floor spreading—molten material adds oceanic crust to the ocean floor
deep ocean trench—valley along ocean floor where oceanic crust slowly sinks toward mantle
continental crust—earth’s lithospheric plates, called “land”; less dense than oceanic crust
The processes of sea-floor spreading and subduction
o
This process, called sea-floor spreading continually adds new material to the ocean floor.
o
Subduction is the process by which the ocean floor sinks into a deep-ocean trench and back
into the mantle.
o
The ocean floor does not just keep spreading. Instead, it sinks into deep underwater canyons
called trenches.
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List the differences between Continental Drift / Sea-floor Spreading / Plate Tectonics
o
Continental Drift- the hypothesis stating that the continents were once connected as one large
landmass (Pangaea) then slowly drifted to their current locations.
Evidence:
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similar fossils on different continents
continents fit together like a puzzle
drastic climate change (fossil from tropical plant found in ice covered area)
Sea-floor Spreading- magma rises up & flows from the mid-ocean ridges. New sea floor is
formed.
o
Plate Tectonics- Earth’s crust & upper mantle is broken into sections (plates). These sections
constantly move on a plastic-like layer of the mantle (called the Asthenosphere). Their movement
is caused by convection currents that occur in the mantle.
Science 8- Earth’s Crust in Motion
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Topographic maps
o Be able to read & interpret information from a topographic map
o
What is the contour interval
of this map? 10 meters
o
What is the elevation of
Able Hill? 40 meters
o
What is the elevation of
Baker Hill? 50 meters
o
Which hill is steeper?
Baker Hill
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Match the following topographic maps with the correct picture
B
E
D
C
F
A
Science 8- Earth’s Crust in Motion