Erosion and Deposition Changing Earth’s Surface Water Erosion The Force of Moving Water Glaciers...

Erosion and Deposition

Changing Earth’s Surface

Water Erosion

The Force of Moving Water

Glaciers

Waves

Wind

Table of Contents


Wearing Down and Building Up

Weathering, erosion, and deposition act together in a cycle that wears down and builds up Earth’s surface.

- Changing Earth’s Surface


Mass Movement

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



Mass Movement Activity

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



Type of Mass Movement

Speed Slope

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

Landslide rapid steep

Mudflow rapid gentle to steep

Slump rapid steep

Creep slow gentle to steep

Mass Movement



Data Sharing Lab

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


End of Section:Changing Earth’s

Surface


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.


Runoff and Erosion

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

- Water Erosion


Erosion by Rivers

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 waterfall’s sharp drop.

- Water Erosion


Erosion by Rivers

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

- Water Erosion


Deposits by Rivers

Deposition creates landforms such as alluvial fans and deltas.

- Water Erosion

Erosion and Deposition - Water Erosion

The Course of a River

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


Groundwater Erosion

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


Groundwater Erosion

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


Previewing VisualsBefore 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.

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

The Course of a River

- Water Erosion


More on Floods

Click the Planet Diary button for an activity about floods.

- Water Erosion


End of Section:Water Erosion


How Water Erodes

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.

- The Force of Moving Water


Erosion and Sediment Load

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



Sediment on the Move

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.




Stream velocity

Reading Graphs:

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




Diameter of sediment particles

Reading Graphs:

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




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

Interpreting Data:

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




Small boulders

Predicting:

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




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

Developing Hypotheses:

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



Erosion and Sediment Load

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



Building VocabularyA 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.

potential energy Potential energy is the energy that is stored and waiting to be used later.

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.

Key Terms: Examples:load

friction

turbulence

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.

Instead of moving downstream, the water moves ever which way in a type of movement called turbulence.


More on River Erosion

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



End of Section:The Force of

Moving Water


How Glaciers Form and Move

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

- Glaciers


How Glaciers Form and Move

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

- Glaciers


How Glaciers Shape the Land

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

- 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.

- Glaciers



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

- Glaciers


Asking QuestionsBefore 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.

What kinds of glaciers are there?

Valley glaciers and continental glaciers

How do glaciers shape the land?

By erosion and deposition

Question Answer

- Glaciers


Links on Glaciers

Click the SciLinks button for links on glaciers.

- Glaciers


End of Section:Glaciers


Erosion by Waves

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

- Waves


Erosion by Waves

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

- Waves


Deposits by Waves

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

- Waves


Main Idea

Detail Detail Detail

Identifying Main IdeasAs 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.

Waves cause erosion by impact and by abrasion.

Energy in waves breaks apart rocks.

Sediment wears away rock.

Landforms are created.

- Waves


Waves

Click the Video button to watch a movie about waves.

- Waves


Links on Waves

Click the SciLinks button for links on waves.

- Waves


End of Section:Waves


How Wind Causes Erosion

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

- Wind


Wind Deposition

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

- Wind


SequencingAs 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.

- Wind


End of Section:Wind


Graphic Organizer

Rills form.

Raindrops strike ground.

Runoff forms.

Gullies form.

Gullies join together.

Stream forms.

Stream Formation


End of Section:Graphic Organizer

Erosion and Deposition Changing Earth’s Surface Water Erosion The Force of Moving Water Glaciers...

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