Ch.9 Erosion and Deposition

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

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

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