Surface Processes on Earth Weathering, Erosion & Freshwater

1. Surface Processes on EarthWeathering, Erosion & Freshwater

2. Weathering and Erosion • Weathering is the process of breaking down rocks at or near the Earth’s surface. • Erosion is the movement of sediments from one place to another.

3. Weathering Mechanical Chemical

4. Mechanical Weathering Does NOT change the rock CHEMICALLY Natural processes just eat away at (Erode) the surface

5. Mechanical Weathering • FROST/ICE WEDGING: repeated thawing and freezing of water in cracks of rocks • UPLIFTING: when layers of rock above are removed, the release of PRESSURE allows the rock to expands and cracks • Plant growth into cracks can split open rocks • EXFOLIATION: the action of EXFOLIATION allows outer rock layers to be striped away

6. Chemical Weathering • Occur when CHEMICAL REACTIONS take place within the rock • Eroded sediments are different chemically • Erosion Increaseswith SURFACE AREA Water, oxygen, carbon dioxide and acids can cause chemical weathering

7. Chemical Weathering Hydrolysis = water. Occurs in Silicate Minerals Oxidation= oxygen. Occurs in Iron Minerals = RUST Carbon dioxide. Combines with water to form a weak CARBONICacid Acid Rain. Released by human activities that make pollution.

8. Rate of Weathering • Water-Solubleminerals weather easily (Like salt melts into salt water) • Different layers weather at different rates

9. Other Factors • More surface area = more weathering • Topography (slopes, hills, etc) allows gravity push sediments downhill faster than on flat surfaces

10. Erosion • Transportation of Sediment Water Wind Glaciers

11. SoilsOr as some call it..Dirt

12. Soils • Soil is made of • Rock particles and minerals (sand, silt, clay) • Humus is organic and provides PLANTS with air and water • Soil Texture depends on particle SIZE

13. Soil Horizons • The layers of soil are called the soil horizon • TOP SOIL – Layer A: contains NUTRIENTS and minerals and is very dark • SUB-SOIL- Layer B: high in clay and is usually red or yellow in color • Layer C: Partially weather rock

14. Life in Soil • Decomposers (such as fungi and bacteria) break down ORGANIC MATERIAL • Animals mix SOIL LAYERS and allow air and water to pass through it. • Humus = Plants produce litter and then decay which returns nutrients to the soil.

15. Soil in the U.S. • Polar (Alaska) – good drainage, no horizons, permafrost • Temperate (Eastern and Central U.S.) – vary greatly • Grassland – fertile • Forest – less fertile • Desert (Western U.S.) – high in salts and little organic/living material • Tropical – can become infertile due to high rainfall

16. Soil Damage • Loss of TOP SOIL • Due to erosion • Desertification • Climate Change, Overgrazing, Cutting down FORESTS

17. Conservation • Contour plowing • CONSERVATIONplowing • Fallow (allowing fields to rest) • CROP rotation

18. Karst Topography • Groundwater contains some ACIDusually CARBONIC ACID • Acid gets there when carbon dioxide combines with water Differential erosion causes KARST TOPOGRAPHY.

19. Features of Karst • Caves • Sinkholes • Stalactites – from above • Stalagmites – from below • Disappearing rivers

20. Karst Topography

22. Caves

24. Sink Holes

25. Stalactites They hold TIGHT to the ceiling

26. Stalagmites They MIGHT have fallen

27. Disappearing Rivers

28. Mass Movement by Gravity • The downward movement of loose sediment and weathered rock. • Slide: moves as a block • Flow: particles mix together • Fall: falling freely

29. Creep Slow, Steady, Downhill flow of sediment

30. Slump Mass of sediment falls down

31. Mudflow swiftly moving mixture of mud and water

32. Landslide downhill movement of saturated topsoil

33. Avalanche Landslides of snow (deep snow)

34. Mass Movement Caused by Wind • Mass movement from wind includes • Dust Storms • Dunes Formation

35. Mass Movement by Glaciers A glacier is a large moving mass of ice

36. The Water Cycle

37. Runoff • Water moving along the surface will carry sediments. • If surface is POROUS, then water can flow into the ground. • Plants slow erosion and allows more water into the ground • Light rains can allow more water into the ground • Soil types affect absorption

38. Run Off & Porosity

39. Watershed • All the land that drains into a stream or river system is called the watershed. Suspension: particles carried in water Bed Load: particles pushed along by water in a stream

40. Streams • Stream channel: the pathway carved by a stream • Stream banks: the ground bordering the stream on either side • Floods occur when streams or rivers rise over their banks. • Flood plain: the broad flat area on either side of the stream banks. • Meander: the bend and curves in a stream

41. Streams

43. Lakes and Freshwater Wetlands • Lakes are depressions in the landscape that collect and hold water. • Eutrophication: the process by which lakes absorb nutrients from the soil around them. • Wetlands are land areas that are covered by water for part of the year. • Bogs • Marshes • Swamps

45. Groundwater and Infiltration • Infiltration is when water on the surface flows into the ground • An aquifer is the area of ground water flow through permeable rock

46. Groundwater

47. Groundwater • Zone of Saturation – the depth to which ground water completely fills all the pores in the material. • Upper boundary is the Water Table • Permeability – how easily water passes through • Zone of Aeration – is the area above the water table

49. Groundwater Systems • Springs - Natural discharges of ground water where ground water is blocked by AQUICLUDES (Clay and Shale) • Hot springs usually form near residual igneous activity • Geysersare explosive hot springs that erupt at regular intervals.