Erosion DEPOSITION PowerPoint PPT Presentation

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2. Erosion & Deposition Terms Erosion is the process that moves weathered rock sediments from one location to another Deposition is the dropping of sediments. Weathering is the breaking down of rock into smaller pieces

3. The following slides show examples of weathering: Chemical & Mechanical

11. Agents of Erosion Gravity Running Water Wind Glaciers All agents of erosion carry sediments when they have energy of motion, and drop them when they lose their energy of motion.

12. Gravity Mass Movements Caused by Gravity: Slumps, Creeps, Rockslides, & Mudflows

14. Slumps A type of mass movement that takes place on steep slopes loose materials slip down as one large mass     doesn’t travel fast or far curved scar is left material underneath slumped

16. Creep leaning things such as telephone pole, fence posts, or trees sediments slowly creep down the hill common where freezing and thawing occur (ice wedging)     ground freezes, pushing up sediments, the ground thaws and the sediments fall downslope less than a mm at a time

18. Rockslide when large blocks or rock break loose from top of steep slopes and tumble to the bottom happen in mountainous areas  happen frequently after earthquakes and heavy rains but can occur without warning “beware of falling rocks” signs  pile of rocks at the bottom of a slope (talus slope)

19. Mudflows thick mixture of sediments and water happen in relatively dry areas where thick layers of dry sediments form heavy rains mix with sediments and form a thick,  pasty substance lots of energy, can move anything in its path ( cars, houses, etc) drops sediments and debris and forms cone- shaped deposits

20. Mudflows

21. Mudflows

23. How All Mass Movements are Similar happen where there is a steep slope all depend on gravity occur frequently after heavy rains erosion of sediments from the top of a slope to further down makes slopes less steep

24. Running Water Erosion Caused by Running Water

25. Running Water Water erodes more sediments than any other agent of erosion. Water moves downslope. When water loses energy, it deposits sediments. Sediments are picked up from the bottoms and sides of streams. Large sediments roll along the bottom; small sediments are picked up and carried by the water. Sediments that are being carried knock even more sediments loose, which causes channels to widen and get deeper

26. Types of Water Erosion

27. Rill Erosion small stream forms during heavy rain carries away plants and soil leaves a scar can lead to gully erosion

28. Gully Erosion .  --carries away large amounts of soil - rill channel gets broader and deeper

29. Sheet Erosion happens outside stream channel water accumulates and eventually starts moving downslope, carrying soil with it water soaks into soil or evaporates, leaving a sheet of soil

31. Water Deposition

32. Water Deposition Some stream sediments travel great distances before being deposited The Coastal Plain region of Virginia was formed from the deposition of sediments eroded from the Appalachian Mountains Water has a lot of energy when flowing downslope- but it loses it when the ground becomes level

33. Types of Water Deposition Alluvial Fans -shaped like a triangle -located on land at the bottom of slopes Delta -sediments are deposited when a channel runs into a gulf, ocean, or lake -triangle-shaped deposits -Mississippi River Delta- largest in United States

34. Alluvial Fans

35. Alluvial Fans

36. Deltas

37. WIND EROSION & Wind Deposition

38. Wind Erosion Deflation- the moving of small sediments Abrasion -compares to sandblasting -grains bump into one another as they roll along ground -grains pit and polish rocks

40. Wind Deposition 2 Types: Dunes & Loess

41. Dunes most common wind deposits happen when sediments blow against an obstacle and pile up form in deserts and beaches dunes on Mars are evidence of wind

42. Dunes

43. Loess Deposits large deposits in United States and China mid-western area has good farming because of these deposits loess deposits of China form from sediments from Gobi and Ordos Deserts fine as talcum powder

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