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Wind Erosion Erosion Mechanical weathering breaks rocks apart, erosion moves the broken pieces. Water Wind Ice Sediment types Sand = larger Silt= small Clay=small…very small Dust (silt and clay)= medium Wind erosion Sand is mostly transported by… Saltation ◦ Moves sediment by a series of jumps and bounces Wind erosion Silt is mostly transported by ◦ Deflation: winds blow sediment into air *dust storms Why only sand and silt Which Climates produce the most deflation? desert is a barren area of land where little precipitation occurs and consequently living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground. Farmers Everything is going to end up somewhere! Sand dune formation a dune is a hill of sand built by either wind or water flow. Formation 1. Wind blows sand 2. Wind is slowed by some type of barrier 3. Accumulation of sand can now occur 4. More sand is added buries original barrier * Limited by angle of repose 30- 40 degrees Loess deposits predominantly silt-sized sediment, which is formed by the accumulation of windblown dust. Formation 1. Wind carries dust and silt 2. Silt is deposited in thin layers 3. Thick layers form from this accumulation *Loess often stands in either steep or vertical faces. loess will often stand in banks for many years without slumping. (unlike sand dunes!) Wave erosion Wave formation usually result from the wind blowing over a vast enough stretch of fluid surface. • wind or some force causes up and down motion of water • Transfers energy Breakers Some waves undergo a phenomenon called "breaking". A breaking wave is one whose base can no longer support its top, causing it to collapse. ◦ Wave hits the bottom of the shore or sand bar ◦ Collides with another wave Wave size 3 Factors affect wind wave size: 1. Wind speed: wind must be moving faster than the wave crest for energy transfer 2. Wind duration: how long the wind blows 3. Fetch Fetch The uninterrupted distance of open water over which the wind blows without significant change in direction. Partner time Westerlies Superior Huron Michigan Erie Ontario Long shore current Waves go at an angle to shoreline ◦ Water moves along shore ◦ Carries sediment with it Shoreline erosion features C A F D E B G Mass movements Also known as mass wasting, is the process by which soil, sand, and rock move downslope largely under the force of gravity. Triggers ◦ ◦ ◦ ◦ ◦ Saturation of water(heavy rain fall) Spring melts Earthquakes/tectonics Wind Humans Mass movements Rockfall/slide: ◦ Sudden movement of rocks, normally in mountain regions Landslide: ◦ Sudden movement of masses of loose rock and soil, down hill/slope. Mudflow: ◦ It is a rapid movement of a large mass of mud formed from loose dirt and water. Mass movements Lahar: ◦ Volcanic mud flow from ash Slump: ◦ Slow moving block of soil moves Down hill Creep: ◦ Very slow movement and very effective of all mass movements Mass movements Solifluction: ◦ slow downslope movement of watersaturated sediment due to recurrent freezing and thawing of the ground, affected by gravity.
