Plate Tectonics Guided Notes
1. What are the three layers of earth? Crust, Mantle, Core
2. Crust- the outermost layer of the Earth, thinnest layer of
the Earth.
3. What are the two types of crust? Continental and Oceanic
4. Continental crust- Has a composition similar to granite
5. Oceanic crust- Composition similar to basalt (denser then
continental, found under the ocean).
6. Mantle- Layer between the crust and core, extremely
thick and contains most of Earth’s mass
7. What percentage of earth’s mass does the mantle make
up? Is any other layer bigger than the mantle? 67%, the
mantle is the biggest of the three layers
How do scientists know anything about the mantle? some places mantle rock has been pushed up to the
surface by tectonic forces; this allows scientists to do
observations.
-scientists also look on the ocean floor, molten rock from
mantle flows out of active volcanoes
8. Core- Mostly iron with smaller amounts of nickel
- center of the Earth
-has an inner core and outer core
-inner core is solid iron and nickel and the outer core is
liquid
Structure of the Earth
1. Draw and label the picture of the earth on pg. 168 and
169.
2. Inner core- Solid, dense center, iron and nickel
3. Outer core- Liquid layer
4. Mesosphere- strong, lower mantle
5. Asthenosphere- soft layer of the mantle (the lithosphere
moves on this)
6. Lithosphere- crust, upper mantle (divided into tectonic
plates)
7. Tectonic plates- pieces of the lithosphere that move
around on top of the asthenosphere
8. What are tectonic plates made of? Both continental and
oceanic crust
9. How do we know so much about the Earth even though
we have only drilled into the crust? Earthquakes occur
producing vibrations called seismic waves.
-Seismic waves- vibrations that travel through the
Earth.
- seismic waves travel through rocks faster than
liquids
-Seismograph- measures the difference in the arrival
times of seismic waves and records them.
Restless Continents pg. 173
1. Continental drift- theory that continents drift apart from
one another and have done so in the past.
2. What was Alfred Wegener’s Theory of Continental Drift?
a. Continents fit together
b. Fossils of species on different sides of the Atlantic
Ocean
c. Glaciers cut grooves in the ground that indicated
the direction of travel.
3. Sea-floor spreading- the process by which new oceanic
lithosphere (crust) is created as older materials are pulled
away.
4. Mid-Atlantic ridge- submerged mountains running
through the center of the Atlantic Ocean.
-this is one of the places where sea-floor spreading takes
place.
5. Explain the process of how sea-floor spreading actually
works? Look on pg. 175. New oceanic lithosphere is
created as older materials are pulled away
- As tectonic plates move away from each other, the sea
floor spreads apart and magma rises to fill in the gap.
- Sea-floor spreading creates new oceanic lithosphere at
the Mid-Atlantic Ridge
- Crust increases in age father it is from the Mid-Atlantic
Ridge
- This is because new crust continually forms from
molten material at the ridge.
- Oldest crust is on the edge of the continent; newest
crust is in the center of the ocean
6. Draw and label the picture of sea-floor spreading on the
bottom of pg. 175.
The Theory of Plate Tectonics
1. Earth’s ____lithosphere______divided into tectonic plates
that move around on top of the asthenosphere.
2. What are the three possible causes of plate tectonics?
a. Ridge push- oceanic plates slides down the
lithosphere-asthenosphere boundary
b. Convection- Hot material deep within Earth rises,
cooler material near surface sinks; when warmer
material cools, becomes denser to sink back
down; this motion on convecting mantle material
drags tectonic plates sideways.
How could this process affect how the Rock Cycle works?
3. Draw, label, and explain the picture of plate tectonics on
the bottom of pg. 177.
4. What are the three types of plate boundaries? Convergent
boundaries, divergent boundaries, transform boundaries
(strike-slip boundaries)
5. Convergent boundaries- two tectonic plates push into one
another
6. Name, explain, and draw a picture of the three types of
convergent boundaries.
a. Continental/continental collision- two continental
plates collide, they buckle, push the crust upward (this
collision form mountains and volcanoes)
b. Continental/Oceanic collision- Oceanic plate slides
under the continental plate, region where the oceanic
plate sinks down into the asthenosphere called the
subduction zone (where igneous rock forms)
c. Oceanic/Oceanic collision- two oceanic plates collide;
one of the plates slides under the other.
7. Divergent boundaries- Two plates move away from one
another
- This is where new oceanic lithosphere (crust) forms.
8. What is the most common type of divergent boundary?
Mid-Atlantic Ridge
9. Transform boundary (Strike-slip)- two plates slide past
each other horizontally
10.
What is an example of a transform boundary? San
Andreas Fault in California
11.
How do scientists measure the movement of
tectonic plates? Since tectonic plates are not smooth;
they grind and jerk as they slide; earthquakes are
produced
- GPS satellites- measure movements of plates
Deforming the Earth’s Crust
-rocks can be put under stress
-stress- amount of force per unit of area
1. Deformation- rock changes its shape due to stress
- Rock layers can bend when stress is placed on them.
2. Compression- type of stress that occurs when an object is
squeezed; as when two plates collide.
-Rock Mountains came from this
3. Tension- forces act to stretch an object.
-this happens at divergent boundaries
4. Folding- when rock layers bend due to stress
5. Draw a picture of the Rocky Mountains on pg. 182 and
draw a line showing where the rocks are folded?
6. Faulting- surface along which rocks break and slide past
each other.
7. What are the two types of faults? Normal and reverse
faults
8. Normal fault: Define and draw a picture.
9. Reverse fault: Define and draw a picture.
10.
How does faulting change how rock layers are
structured? Rocks either pull apart due to tension or
rocks are pushed together by compression
11.
Strike-slip fault- opposing forces cause rocks to
break and move horizontally.
12.
How do plate tectonics cause mountains to form?
Mountains exist because constantly plates are bumping
into each other.