2Erosion and Deposition by Wind State standards:6.2: Topography is reshaped by the weathering of rock and soil and by the transportation and deposition of sediment.
3Erosion and Deposition by Wind Students will be able to understand that wind shapes the landscape with the process of erosion and deposition by illustrating and describing these processes in a poster or foldable.
4Erosion and Deposition by Wind Today we will explore how wind shapes the landscape. We will also discover what features are formed by wind erosion and wind deposition.
5Erosion and Deposition by Wind During this presentation there will be some questions to check what we have learned today. There will also be some questions to answer as an exit paper.
6How does wind cause erosion? Erosion by WindHow does wind cause erosion?
7Wind causes erosion by deflation. Erosion by WindWind causes erosion by deflation.Deflation is the process by which wind removes surface material.When wind blows over the land, it picks up the smallest particles of sediment.
8DeflationDeflation moves sediment particles of different sizes in the three ways shown below.Suspension: Fine particles are carried through air.Saltation: Medium-sized particles skip or bounce.WindCreep: Larger-sized particles slide or roll.
9DeflationIn the desert, deflation by saltation can remove all the smaller pieces of sediment.This leaves behind larger, angular pieces of sediment.This remaining sediment is referred to as desert pavement.
11Abrasion by wind can polish rock, but it causes little erosion. At one time, geologists thought that the sediment carried by wind cut the stone shapes seen in the desert.However, now evidence shows that most desert landforms are the result of weathering and water erosion.
12What are the two ways wind causes erosion? Check UnderstandingWhat are the two ways wind causes erosion?One way wind causes erosion is deflation.The other way is abrasion.
13What are the three types of deflation? Check UnderstandingWhat are the three types of deflation?suspensionsaltationcreep
14What is an example of deflation by saltation? Check UnderstandingWhat is an example of deflation by saltation?An example of deflation by saltation is desert pavement.
15What features are created by wind deposition? Deposition by WindWhat features are created by wind deposition?
16Deposition by WindWind deposition may form sand dunes and loess deposits.
17Sand Dunes Sand dunes are deposits of wind-blown sand. Over thousands of years, wind sweeps sand into huge, ever-changing dunes
18Sand DunesSand dunes come in many shapes and sizes. Some are long, with parallel ridges. Others are U-shaped.They can be small or very large.Sand dunes move over time.
19Sand DunesCrescent-shaped dunes form where the wind usually blows in the same direction.
20Sand DunesStar-shaped dunes form where the wind direction changes frequently.
21Sand DunesIn California, sand dunes occur along the coast where rivers have supplied sand to bays, like Humboldt Bay.
22Sand DunesAreas of sand dunes also can be found in Death Valley and the Mojave desert.
23Loess DepositsLoess is fine, wind-deposited sediment that is finer than sand, such as particles of clay and silt.
24Loess DepositsLoess sediment is carried by the wind in suspension and is sometimes deposited in layers far from the source.
25Loess DepositsLarge loess deposits can be found in central China and in the midwestern United States.
26Loess DepositsLoess helps to form fertile soil. Many areas with thick loess deposits are valuable farmlands.Loess is easily eroded by water runoff.
27What are deposits of wind-blown sand? Check UnderstandingWhat are deposits of wind-blown sand?Deposits of wind-blown sand are sand dunes.
28What are two shapes that sand dunes can form? Check UnderstandingWhat are two shapes that sand dunes can form?Sand dunes can form crescent-shaped dunes and star-shaped dunes.
29How are star-shaped sand dunes formed? Check UnderstandingHow are star-shaped sand dunes formed?Star-shaped Sand dunes are formed by different wind directions.
30What are two characteristics of loess deposits? Check UnderstandingWhat are two characteristics of loess deposits?Two characteristics of loess deposits are they are fertile and they are easily eroded.
31Review Wind Erosion is by deflation and abrasion. Deflation can occur as suspension, saltation, or creep.Abrasion causes little erosion.Wind deposition can be found in sand dunes or loess deposits.Sand dunes come in many shapes or sizes.Loess deposits can be very fertile and erode easily.
32Exit QuestionsOn your exit paper, write the answer to the following questions:
33How does wind cause erosion? Erosion by WindHow does wind cause erosion?
34What features are created by wind deposition? Deposition by WindWhat features are created by wind deposition?
35Independent ActivityCreate a poster (or foldable) on an 8.5” x 11” sheet of paper that illustrates and describes the processes of wind erosion and deposition and the features that are created.suspensionsaltationcreep