Erosion and Deposition by Wind

Erosion 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.

Erosion 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.

Erosion 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.

Erosion 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.

How does wind cause erosion? Erosion by Wind How does wind cause erosion?

Wind causes erosion by deflation. Erosion by Wind Wind 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.

Deflation Deflation 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. Wind Creep: Larger-sized particles slide or roll.

Deflation In 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.

Desert Pavement

Abrasion 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.

What are the two ways wind causes erosion? Check Understanding What are the two ways wind causes erosion? One way wind causes erosion is deflation. The other way is abrasion.

What are the three types of deflation? Check Understanding What are the three types of deflation? suspension saltation creep

What is an example of deflation by saltation? Check Understanding What is an example of deflation by saltation? An example of deflation by saltation is desert pavement.

What features are created by wind deposition? Deposition by Wind What features are created by wind deposition?

Deposition by Wind Wind deposition may form sand dunes and loess deposits.

Sand Dunes Sand dunes are deposits of wind-blown sand. Over thousands of years, wind sweeps sand into huge, ever-changing dunes

Sand Dunes Sand 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.

Sand Dunes Crescent-shaped dunes form where the wind usually blows in the same direction.

Sand Dunes Star-shaped dunes form where the wind direction changes frequently.

Sand Dunes In California, sand dunes occur along the coast where rivers have supplied sand to bays, like Humboldt Bay.

Sand Dunes Areas of sand dunes also can be found in Death Valley and the Mojave desert.

Loess Deposits Loess is fine, wind-deposited sediment that is finer than sand, such as particles of clay and silt.

Loess Deposits Loess sediment is carried by the wind in suspension and is sometimes deposited in layers far from the source.

Loess Deposits Large loess deposits can be found in central China and in the midwestern United States.

Loess Deposits Loess helps to form fertile soil. Many areas with thick loess deposits are valuable farmlands. Loess is easily eroded by water runoff.

What are deposits of wind-blown sand? Check Understanding What are deposits of wind-blown sand? Deposits of wind-blown sand are sand dunes.

What are two shapes that sand dunes can form? Check Understanding What are two shapes that sand dunes can form? Sand dunes can form crescent-shaped dunes and star-shaped dunes.

How are star-shaped sand dunes formed? Check Understanding How are star-shaped sand dunes formed? Star-shaped Sand dunes are formed by different wind directions.

What are two characteristics of loess deposits? Check Understanding What are two characteristics of loess deposits? Two characteristics of loess deposits are they are fertile and they are easily eroded.

Review 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.

Exit Questions On your exit paper, write the answer to the following questions:

How does wind cause erosion? Erosion by Wind How does wind cause erosion?

What features are created by wind deposition? Deposition by Wind What features are created by wind deposition?

Independent Activity Create 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. suspension saltation creep