- How flowing water causes erosion and deposition
- Erosion and deposition by surface water
- Erosion and deposition by groundwater
- Explain how flowing water causes erosion and deposition.
- Describe how runoff, streams, and rivers change Earth’s surface.
- Identify features caused by groundwater erosion and deposition.
alluvial fan: landform created where a mountain stream suddenly flows onto flatter land and deposits its sediments
cave: underground hole or cavern eroded by groundwater
delta: triangular landform created where a river empties into a body of still water and deposits its sediments
deposition: process by which eroded sediments are dropped somewhere else by an agent of erosion
erosion: transport of sediments by moving water, wind, glaciers, or gravity
floodplain: broad flat area on both sides of a river where it deposits its sediments when it floods its banks
levee: raised strip of sediments deposited along the bank of a river when it overflows its channel
meander: large curve in a stream caused by erosion of the outside of a curve and deposition on the inside of a curve
oxbow lake: body of water that forms when a meander is cut off from the rest of the river
saltation: transport of small particles such as sand in little jumps along a streambed
sinkhole: circular hole in the surface of the ground that forms when the roof of a cave collapses
suspension: transport of very small particles such as clay that are carried by the main stream flow but are not dissolved by the water
traction: transport of large particles such as gravel and stones by rolling or dragging along the bottom of the water
Introducing the Lesson
Introduce erosion by flowing water with a simple demonstration. Pour a small stream of water from a pitcher on top of a mound of soil containing a mix of particle sizes including small pebbles. Ask students to identify and describe the process they are observing. (erosion by flowing water) Tell students they will learn how flowing water causes erosion in this lesson.
You may want to use the lesson plan and one or more of the four activities presented at the URL below when you teach erosion and deposition by flowing water. The lesson plan uses as a focus the formation of the Grand Canyon, which also opens this chapter in the FlexBook® resource. In the activities, students can model erosion and deposition by flowing water. They can also investigate how slope and volume of water affect water velocity and erosion. Skills students will practice include making models, making and recording observations, and identifying and controlling variables.
Have less proficient readers make a concept map of the important concepts in the lesson. This will help them see how lesson content is organized and how the concepts are related. They should include the following concepts: erosion by streams, types of load (dissolved, suspended, and bed loads), stages of streams, and deposition by streams (natural levees, alluvial fans, and deltas).
The words erosion and deposition from this lesson’s vocabulary list are good words to add to a word wall. Assign each word to a different pair of students. Partners should write the term on a large index card, define the term, and add an example and sketch.
Ask a few students to collaborate on making a diorama to illustrate erosion and deposition by a river. The diorama should represent a three-dimensional landscape with a river running through it. It should show how the river erodes its bed near its headwaters where the slope is steep and how it erodes its banks closer to its base level where its slope is gentle. The diorama should also include features such as an alluvial fan, meanders, a floodplain, and a delta. Each feature should be labeled. Display the completed diorama in a prominent place in the classroom.
Have students investigate the effect of slope on erosion by flowing water with an activity like the one at the URL below (Station 12, “Slope and Erosion”). Discuss how the activity relates to erosion by actual streams.
Students often think that erosion is always bad. Stress that erosion also has positive aspects. Floodplains and deltas are covered with sediments deposited by rivers. The soils in these areas are rich and fertile, making them excellent for farmland. These areas would not exist without erosion.
Reinforce and Review
Copy and distribute the lesson worksheets in the CK-12 Earth Science for Middle School Workbook. Ask students to complete the worksheets alone or in pairs to reinforce lesson content.
Lesson Review Questions
Have students answer the Review Questions listed at the end of the lesson in the FlexBook® student edition.
Check students’ mastery of the lesson with Lesson 10.1 Quiz in CK-12 Earth Science for Middle School Quizzes and Tests.
Points to Consider
Ocean waves are another form of moving water. They also cause erosion and deposition. How do waves erode shorelines?
What landforms are deposited by waves?