Changing Earth

1
Table of Contents

• Changing Earths Surface
• Water Erosion
• The Force of Moving Water
• Glaciers
• Waves
• Wind

2
Wearing Down and Building Up
- Changing Earths Surface

• Weathering, erosion, and deposition act together
  in a cycle that wears down and builds up Earths
  surface.

3
Mass Movement
- Changing Earths Surface

• The different types of mass movement include
  landslides, mudflows, slump, and creep.

4
Mass Movement Activity
- Changing Earths Surface

• Click the Active Art button to open a browser
  window and access Active Art about mass movement.

5
Comparing and Contrasting
- Changing Earths Surface

• As you read, compare and contrast the different
  types of mass movement by completing a table like
  the one below.

Mass Movement
Type of Mass Movement
Speed
Slope
Landslide
rapid
steep
Mudflow
rapid
gentle to steep
Slump
rapid
steep
Creep
slow
gentle to steep
6
Data Sharing Lab

• Click the PHSchool.com button for an activity
  about sharing data for the Skills Lab Sand Hills.

7
End of SectionChanging Earths Surface
8
Runoff and Erosion
- Water Erosion

• Precipitation over the United States averages
  about 75 cm per year. About 22.5 cm becomes
  runoff. Generally, more runoff means more
  erosion.

9
Runoff and Erosion
- Water Erosion

• Water flowing across the land runs together to
  form rills, gullies, and streams.

10
Erosion by Rivers
- Water Erosion

• A waterfall forms where a flat layer of tough
  rock lies over a layer of softer rock that erodes
  easily. When the softer rock erodes, pieces of
  the harder rock above break off, creating the
  waterfalls sharp drop.

11
Erosion by Rivers
- Water Erosion

• Erosion often forms meanders and oxbow lakes
  where a river winds across its floodplain.

12
Deposits by Rivers
- Water Erosion

• Deposition creates landforms such as alluvial
  fans and deltas.

13
The Course of a River
- Water Erosion

• The slope and size of a river, as well as the
  sediment it carries, determine how a river shapes
  the land.

14
Groundwater Erosion
- Water Erosion

• Karst topography is found in many parts of the
  United States where the bedrock is made up of
  thick layers of limestone.

15
Groundwater Erosion
- Water Erosion

• Chemical weathering of limestone and groundwater
  erosion can create a limestone cave.

16
Previewing Visuals
- Water Erosion

• Before you read, preview Figure 10. Then write
  two questions you have about the illustration in
  a graphic organizer like the one below. As you
  read, answer your questions.

The Course of a River
Q. What features does a river produce by erosion?
A. V-shaped valley, bluffs
Q. What feature does a river produce by
deposition?
A. Delta
17
More on Floods
- Water Erosion

• Click the Planet Diary button for an activity
  about floods.

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End of SectionWater Erosion
19
How Water Erodes
- The Force of Moving Water

• Most sediment washes or falls into a river as a
  result of mass movement and runoff. Other
  sediment erodes from the bottom or sides of the
  river. Streams carry sediment in several ways, as
  shown in the diagram.

20
Erosion and Sediment Load
- The Force of Moving Water

• A rivers slope is usually greatest near the
  rivers source. As a river approaches its mouth,
  its slope lessens.

21
Sediment on the Move
- The Force of Moving Water

• The speed, or velocity, of a stream affects the
  size of the sediment particles the stream can
  carry. Study the graph, then answer the following
  questions.

22
Sediment on the Move
- The Force of Moving Water

• Reading Graphs
• What variable is shown on the x-axis of the graph?

• Stream velocity

23
Sediment on the Move
- The Force of Moving Water

• Reading Graphs
• What variable is shown on the y-axis of the graph?

• Diameter of sediment particles

24
Sediment on the Move
- The Force of Moving Water

• Interpreting Data
• What is the speed at which a stream can move
  coarse sand? Small pebbles? Large boulders?

• About 50 cm/sec about 90 cm/sec about 800 cm/sec

25
Sediment on the Move
- The Force of Moving Water

• Predicting
• A streams speed increases to about 600 cm per
  second during a flood. What are the largest
  particles the stream can move?

• Small boulders

26
Sediment on the Move
- The Force of Moving Water

• Developing Hypotheses
• Write a hypothesis that states the relationship
  between the speed of a stream and the size of
  sediment particles it can move.

• The faster the speed of the flowing water, the
  larger the particles the stream is able to move.

27
Erosion and Sediment Load
- The Force of Moving Water

• A river erodes sediment from its banks on the
  outside curve and deposits sediment on the inside
  curve.

28
Building Vocabulary
- The Force of Moving Water

• A definition states the meaning of a word or
  phrase by telling about its most important
  feature or function. Carefully read the
  definition of each Key Term and also read the
  neighboring sentences. Then write a definition of
  each Key Term in your own words.

Key Terms
Examples
energy
Energy is the ability to do work or cause change.
The amount of sediment that a river carries is
its load.
Friction is the force that opposes the motion of
one surface as it moves across another surface.
potential energy
Potential energy is the energy that is stored and
waiting to be used later.
Instead of moving downstream, the water moves
ever which way in a type of movement called
turbulence.
kinetic energy
Kinetic energy is the energy an object has due to
its motion.
abrasion
Abrasion is the wearing away of rock by a
grinding action.
29
More on River Erosion
- The Force of Moving Water

• Click the PHSchool.com button for an
  activityabout river erosion.

30
End of SectionThe Force of Moving Water
31
How Glaciers Form and Move
- Glaciers

• A continental glacier is a glacier that covers
  much of a continent or large island.

32
How Glaciers Form and Move
- Glaciers

• During the last ice age, a continental glacier
  covered most of northern North America.

33
How Glaciers Shape the Land
- Glaciers

• As a glacier moves, plucking breaks pieces of
  bedrock from the ground.

34
How Glaciers Shape the Land
- Glaciers

• Erosion by glaciers can carve a mountain peak
  into a sharp horn and grind out a V-shaped valley
  to form a U-shaped valley.

35
How Glaciers Shape the Land
- Glaciers

• As glaciers advance and retreat, they sculpt the
  landscape by erosion and deposition.

36
Asking Questions
- Glaciers

• Before you read, preview the red headings. In a
  graphic organizer like the one below, ask a what,
  how, or where question for each heading. As you
  read, write answers to your questions.

Question
Answer
What kinds of glaciers are there?
Valley glaciers and continental glaciers
How do glaciers shape the land?
By erosion and deposition
37
Links on Glaciers
- Glaciers

• Click the SciLinks button for links on glaciers.

38
End of SectionGlaciers
39
Erosion by Waves
- Waves

• Waves shape the coast through erosion by breaking
  down rock and transporting sand and other
  sediment.

40
Erosion by Waves
- Waves

• Erosion and deposition create a variety of
  features along a coast.

41
Deposits by Waves
- Waves

• Waves shape a coast when they deposit sediment,
  forming coastal features such as beaches, spits,
  and barrier beaches.

42
Identifying Main Ideas
- Waves

• As you read the section Erosion by Waves, write
  the main idea in a graphic organizer like the one
  below. Then write three supporting details that
  further explain the main idea.

Main Idea
Waves cause erosion by impact and by abrasion.
Detail
Detail
Detail
Energy in waves breaks apart rocks.
Sediment wears away rock.
Landforms are created.
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Waves
- Waves

• Click the Video button to watch a movie about
  waves.

44
Links on Waves
- Waves

• Click the SciLinks button for links on waves.

45
End of SectionWaves
46
How Wind Causes Erosion
- Wind

• Wind erosion moves sediment particles of
  different sizes in the three ways shown below.

47
Wind Deposition
- Wind

• Wind erosion and deposition may form sand dunes
  and loess deposits.

48
Sequencing
- Wind

• As you read, make a flowchart like the one below
  that shows the process of wind erosion and
  deposition. Write each step of the process in a
  separate box in the flowchart in the order in
  which it occurs.

Wind Erosion
Wind picks up smallest particles of sediment.
Fine particles are carried through the air.
Medium-sized particles skip and bounce.
Larger particles slide or roll.
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End of SectionWind
50
Graphic Organizer
Stream Formation

Raindrops strike ground.
Runoff forms.
Rills form.
Gullies form.
Gullies join together.
Stream forms.
51
End of SectionGraphic Organizer