Name ______________________________________ Date _________
TEKS Review
3.7B
TEKS 3.7B investigate rapid changes in Earth’s surface such as volcanic eruptions, earthquakes,
and landslides
Rapid Changes in Earth’s Surface
Constant Changes
Earth’s surface is constantly changing.
Wind, water, and ice break down large rocks
and move sediments on the surface. It usually
takes years for weathering, erosion, and
deposition to cause noticeable changes. Some
events, though, change Earth’s surface much
more quickly. These include volcanic
eruptions, earthquakes, and landslides. These
events have the ability to cause large changes
in a much shorter period of time.
Earth’s Structure
From its surface, Earth appears to be
made of solid rock. If it were possible to travel
about 6,000 km (4,000 mi) to the center of
Earth you would find that Earth is actually
composed of layers. As you go deeper, the
pressure and temperature increase. Each layer
has different properties.
Crust
5–70 km (3–43 mi) thick
The crust is the surface
layer of Earth.
The crust, which makes up the surface, is
the thinnest of the layers. The crust is solid
rock. So is most of the next layer, the mantle.
But some rock within the mantle is soft, like
melted candy. Below the mantle is the outer
core. The outer core is liquid, but it is iron, not
rock. The inner core is also metal, but it’s
solid due to intense pressure.
Plate Tectonics
Earth’s crust and uppermost mantle are
divided into sections, called plates. Plates are
blocks of crust and upper mantle rock that fit
together like puzzle pieces. Plates “float” on
the softer rock of the mantle. As this rock
flows, plates slowly move. Because the plates
fit together so closely, the movement of one
plate affects other plates.
At different places, plates move toward
each other, away from each other, or alongside
each other. These plate movements are
responsible for earthquakes.
Mantle
2,885 km (1,790 mi) thick
The mantle is made of
rock. The upper mantle is
partially melted
Outer Core
2,270 km (1,410 mi) thick
Inner Core
1,210 km (750 mi) thick
TEKS Review and Assessment
© Houghton Mifflin Harcourt Publishing Company
TEKS 3.7B
Earth’s tectonic plates fit together
like puzzle pieces. They move very
slowly—just a few centimeters per
year. Texas is located on the North
American plate.
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Name ______________________________________ Date _________
TEKS Review
3.7B
Earthquakes
Suppose you press your hands together as
hard as you can. If one hand slips, energy is
released suddenly and your hands move past
each other. The same thing happens in Earth’s
crust. The movement of plates causes pressure
to build up where two plates are colliding or
sliding past one another. These areas are
called faults, which are breaks in Earth’s
crust. When the pressure builds to a certain
point, the plates move, energy is released, and
the ground shakes.
An earthquake is a shaking of the
ground caused by a sudden release of energy
in Earth’s crust. Most earthquakes are too
small to be felt, but they can be measured
using a seismometer. Strong earthquakes can
cause a great deal of damage to buildings and
roads.
Earthquakes cause rapid changes to
Earth’s surface. They may cause the ground to
rupture, or break, along the fault. A major
earthquake can move land several meters.
An earthquake in the ocean floor can
transfer energy to the water above and cause a
tsunami. A tsunami is a fast-moving wave
that can cause a large volume of water to flow
onshore and damage coastal regions. Often, a
tsunami washes away everything in its path.
Volcanoes
The melted rock in Earth’s mantle is
called magma. In some places, magma
reaches the surface. A volcano is a vent, or
opening, in the surface of Earth through which
magma and hot gases erupt. Magma is called
lava when it reaches the surface. In addition to
lava, materials ejected from the vent could
include cinder, pumice, and ash.
TEKS Review and Assessment
© Houghton Mifflin Harcourt Publishing Company
Volcanoes can change Earth’s surface in
many ways. Flowing lava and ejections of
cinder, pumice, and ash build up to create
volcanic mountains. A powerful eruption can
destroy trees many kilometers away as hot
gases and ash flow from the volcano. Ash can
be sent high into Earth’s atmosphere. The ash
from a volcanic eruption forms very fertile
soils over time.
Volcanic activity lays down thick, dense
layers of rock. The Hawaiian Islands were
formed by volcanic activity, which continues
today. Similarly, melted rock cools and forms
new land where two plates are pulling apart.
Most volcanoes go through long periods
during which they are dormant, or inactive.
During this time, the crater at the volcano’s
peak may fill with water and form a lake.
Sinkholes
If you dig deep enough into the soil, you
will eventually find rock. Sometimes,
underground water wears away rock and
forms a cave underground. If the cave
collapses, the ground above falls into it. This
forms a sinkhole on Earth’s surface.
TEKS 3.7B
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Name ______________________________________ Date _________
Landslides
If you have ever taken a trip through a
mountainous area, you may have seen road
signs warning of falling rocks. Weathering
causes rocks to break free, and gravity pulls
them tumbling down the mountainside.
Sometimes, the same thing happens with a
large area of rock or soil at once. A landslide
is the fast movement of soil and rocks down a
slope. Landslides can be very dangerous.
TEKS Review
3.7B
Landslides occur in the ocean, along the
coast, and on shore. Many factors determine
how stable a slope is. Some landslides occur
naturally. They are set off by heavy rains,
floods, earthquakes, or volcanoes. Excessive
human development and construction grading
can also cause landslides.
Hands-On Activity
Materials
Make a Landslide
There is a maximum slope that can exist for any given soil. We will
investigate this slope with different types of materials.
Procedure:
1. Cover the lab table or desk with paper to help with cleanup.
Slowly pour the dry sand through the funnel onto the flat
surface so that it makes a pile. Take notes about what
happens to the sides of the pile as you pour the sand.
• 500 mL each of fine
sand, mud, gravel,
potting soil, and
sugar, in separate
containers
• funnel
• protractor
• paper to cover the
desk
2. Hold a protractor upright in the pile of sand so that you can
measure the angle of the side of the pile. Read and record the angle in degrees.
What happens if you add more sand to the pile? How does the measurement change?
3. After you have cleaned up all of the sand, repeat steps 1 and 2 with the mud, gravel,
potting soil, and sugar.
4. Compare the angles for all the materials.
Discussion Questions:
1. What happened to the sides of the pile as you poured the sand?
2. How does the angle change for each material?
TEKS Review and Assessment
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TEKS 3.7B
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TEKS Review
3.7B
Name ______________________________________ Date _________
Volcanoes and Landslides
Read each statement and write T for true or F for false.
_____ Magma that reaches the surface and flows from a volcano is called lava.
_____ The thick layer of rock beneath Earth’s crust is called the mantle.
_____ A crater is the name of the hole at the top of the volcano’s vent. It may contain a lake.
_____ Dormant is the word used to describe a volcano that is erupting.
_____ Gases, molten rock, lava, and rocks are thrown out of an erupting volcano.
_____ Earth’s plates move several meters each year.
_____ Landslides are always very large.
_____ Landslides frequently occur during periods of intense rainfall or rapid snow melt.
_____ Landslides in the United States occur only on the coastlines.
_____ Earthquakes can cause the crust to crack.
Volcano Diagram
Label the diagram by using the words in the word bank.
b.
Word Bank
gases, ashes, and cinders
lava
vent
magma
c.
a.
d.
TEKS Review and Assessment
© Houghton Mifflin Harcourt Publishing Company
TEKS 3.7B
Page 4 of 6
Name ______________________________________ Date _________
TEKS Review
3.7B
TEKS Assessment 3.7B
Fill in the letter of the best choice.
Volcanoes and earthquakes are most
likely to occur—
What occurs when the pressure that has
built between two plates is suddenly
released?
in the center of a plate
at plate boundaries
new crust forms instantly
along the coast of a continent
volcanoes occur slowly
anywhere
earthquakes happen suddenly
mountains form quickly
What causes the movement of Earth’s
plates?
Use the drawing below to answer
questions 6–7.
landslides
A
ocean currents
shaking that occurs in Earth’s
inner core
movement of melted rock in
the mantle
What is a fault?
a place on Earth where earthquakes
cannot occur
a fracture on Earth’s surface where
movement has occurred
the place where the most damage
occurs during earthquakes
another name for an earthquake
Which location is most likely to be
damaged by a tsunami?
What do the arrows represent?
the motion of plates
the eruption of a volcano
the cause of a tsunami
the formation of a crater
What is the area labeled A called?
joint
fault
a coastline
canyon
a volcanic crater
plate
a rain-soaked slope
a snow-covered mountainside
TEKS Review and Assessment
© Houghton Mifflin Harcourt Publishing Company
TEKS 3.7B
Page 5 of 6
Name ______________________________________ Date _________
TEKS Review
3.7B
Hands-On Activity (p. 3)
1. At first, the pile will grow higher. Once it reaches a certain height, particles that land near
the top of the pile will be pulled down the sides of the pile by gravity. The particles will
not form a structure that is steeper than a certain angle.
2. Answers will vary, but should be based on the measurements taken with the protractor.
Student Response Activity (p. 4)
1. T
6. F
11. a. lava
2. T
7. F
b. gases, ashes, and cinder
3. T
8. T
c. vent
4. F
9. F
d. magma
5. T
10. T
TEKS Assessment (p. 5)
1. B
2. D
3. B
4. A
5. C
6. A
7. B
TEKS Review and Assessment
© Houghton Mifflin Harcourt Publishing Company
TEKS 3.7B
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