Wind
Anticipation guide # 3 Creep is a type of mass movement that happens slowly over many years Oxidation is a type of physical weathering A delta is a depositional feature that occurs with glaciers The velocity of a stream is related to the steepness of the slope. The biggest threat from a volcanic eruption is the mass movements they create
VA SOL SOL 8 The student will investigate and understand geologic processes... Key concepts include b. processes ( weathering, erosion, deposition, and sedimentation) and their resulting features.
Objective 2 Define deposition as the process by which Earth materials carried by wind, water, or ice settle out and are deposited. 3 Describe the agents of erosion: gravity, water (running water and waves), glaciers, and wind.
Enduring Understandings Weathering, erosion, and deposition are interrelated processes that form a cycle of forces that wear down and build up the Earth s surface.
Wind Erosion Moving air can pick up and transport Earth materials in the process of erosion. A current of rapidly moving air can pick up and carry sediments in the same way that other agents do. Wind is unique in that it can also transport sediments upslope against the force of gravity.
Wind Erosion Wind generally cannot carry particles as large as those transported by moving water and glaciers
Wind Erosion Hurricanes and tornadoes are the exception
Wind Transport Winds transport materials in different methods depending on the particle size and wind velocity
Wind Transport Suspension is the method of transport by which particles stay airborne for long periods
Wind Transport Saltation is transportation of particles by a bouncing motion
Wind Transport Particles also move by simply rolling along the ground as the wind pushes them
Wind Erosion Areas that receive limited amounts of precipitation are most susceptible to wind erosion.
Wind Erosion Precipitation helps to hold down the sediments and allows the plants to grow which helps curb the effects of wind erosion
Wind Erosion Deflation is the lowering of land surface as a result of wind erosion
Wind Erosion Abrasion occurs when particles such as sand rub against the surface of rocks and wears them down
Wind Erosion Since many sand particles are made of the hard mineral quartz, wind abrasion can be a very effective agent of erosion
Wind Erosion Ventifacts are rocks shaped by windblown sediments
Wind Deposition Wind deposition occurs in areas where there is a change in wind velocity as materials can no longer stay moving and form a deposit on the ground
Dunes When wind-blown particles tend to accumulate where an object such as a rock or piece of vegetation blocks movement
Dune Dune is a pile of accumulated windblown sand
Dune The conditions under which a dune forms such as availability of sand, wind velocity and direction and the presence of vegetation determines the shape of the sand dune
Types of Dunes Barchan dunes are solitary crescent shaped dunes that form in flat areas where there is little sand or vegetation
Types of Dunes Transverse dunes form where there is plenty of sand, little or no vegetation, and strong, steady prevailing winds
Types of Dunes Parabolic dunes are U-shaped and form between clumps of vegetation
Types of Dunes Longitudinal dunes form in areas where there is limited sand available and strong prevailing wind
Dunes Dunes are very important to the environment. Coastal dunes protect against beach and coastal erosion by reducing the direct action of wind on beach sand
Dunes Vegetation helps to anchor coastal dunes
Dunes Human activities such as building in coastal dune areas have increased beach erosion and nearshore flooding because of disruptions to the dune building process
Loess Many parts of Earth s surface are covered with thick layers of windblown silt. Where precipitation is adequate loess soils are some of the most fertile
Loess The fertile Midwestern states have loess soils