Table of Contents Changing Earth’s Surface Water Erosion The Force of Moving Water Glaciers Waves Wind

Wearing Down and Building Up - Changing Earth’s Surface Wearing Down and Building Up Weathering, erosion, and deposition act together in a cycle that wears down and builds up Earth’s surface.

Mass Movement - Changing Earth’s Surface The different types of mass movement include landslides, mudflows, slump, and creep.

Mass Movement Activity - Changing Earth’s Surface Mass Movement Activity Click the Active Art button to open a browser window and access Active Art about mass movement.

Comparing and Contrasting - Changing Earth’s Surface Comparing and Contrasting 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

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

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 waterfall’s sharp drop.

Erosion by Rivers - Water Erosion Erosion often forms meanders and oxbow lakes where a river winds across its floodplain.

Deposits by Rivers - Water Erosion Deposition creates landforms such as alluvial fans and deltas.

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.

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.

Groundwater Erosion - Water Erosion Chemical weathering of limestone and groundwater erosion can create a limestone cave.

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

Click the Planet Diary button for an activity about floods. - Water Erosion More on Floods Click the Planet Diary button for an activity about floods.

End of Section: Water Erosion

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.

Erosion and Sediment Load - 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 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.

Sediment on the Move - The Force of Moving Water Reading Graphs: What variable is shown on the x-axis of the graph? Stream velocity

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

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

Sediment on the Move - The Force of Moving Water Predicting: A stream’s speed increases to about 600 cm per second during a flood. What are the largest particles the stream can move? Small boulders

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.

Erosion and Sediment Load - The Force of Moving Water Erosion and Sediment Load A river erodes sediment from its banks on the outside curve and deposits sediment on the inside curve.

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: load friction turbulence Key Terms: Examples: energy The amount of sediment that a river carries is its load. Energy is the ability to do work or cause change. potential energy Friction is the force that opposes the motion of one surface as it moves across another surface. 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.

Click the PHSchool.com button for an activity about river erosion. - The Force of Moving Water More on River Erosion Click the PHSchool.com button for an activity about 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.

How Glaciers Form and Move During the last ice age, a continental glacier covered most of northern North America.

How Glaciers Shape the Land As a glacier moves, plucking breaks pieces of bedrock from the ground.

How Glaciers Shape the Land 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.

How Glaciers Shape the Land As glaciers advance and retreat, they sculpt the landscape by erosion and deposition.

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

Click the SciLinks button for links on glaciers.

End of Section: Glaciers

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

Erosion by Waves - Waves Erosion and deposition create a variety of features along a coast.

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

Identifying Main Ideas - Waves Identifying Main Ideas 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.

Click the Video button to watch a movie about waves.

Click the SciLinks button for links on 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 Sequencing 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.

End of Section: Wind

Raindrops strike ground. Graphic Organizer Stream Formation Raindrops strike ground. Runoff forms. Rills form. Gullies form. Gullies join together. Stream forms.

End of Section: Graphic Organizer