Ch.9

1. Ch.9 Erosion and Deposition

2. Section 6: Wind • How Wind Causes Erosion • Sand dune is a deposit of wind-blown sand • Wind causes erosion by deflation and abrasion • Deflation • The main way that wind causes erosion is by deflation which is the process by which wind removes surface materials • Deflation does not usually have a great effect on land • Ex: parts of the Great Plains in the 1930’s deflation caused the loss of about 1 meter of topsoil in just a few years

3. Section 6: Wind • How Wind Causes Erosion • Abrasion • By wind-carried sand can polish rock, but it causes little erosion • At one time, geologists thought that the sediment carried by wind cur the stone shapes seen in deserts • But now evidence shows that most desert landforms as the result of weathering and water erosion

4. Section 6: Wind • Wind Deposition • Wind erosion and deposition may form sand dunes and loss deposits • Sand Dunes • Come in many shapes and sizes such as: long, with parallel ridges, while others are U-shaped • Sand dunes move over time, little by little, the sand shifts with the wind from one side of the dune to another • Loess Deposits • Sediment that is finer than sand, such as particles of clay and silt, is sometimes deposited in layers far from its source • This fine, wind-deposited sediment is loess • Ex: found in Nebraska, South Dakota, Iowa, Missouri