1. Weathering and Erosion

2. Day 1 Objective: – I can explain how weathering occurs on Earth

3. What is Weathering? Is the breaking down and changing of rocks near Earth’s surface Two Types – Mechanical – Chemical

4. What is Mechanical Weathering ? When physical forces break rock into smaller pieces Does not change the rock’s composition Three Ways – Frost Wedging – Unloading – Biological Activity

5. Mechanical Weathering: Frost Wedging Water enters cracks and crevices in rocks Water freezes expanding the cracks Eventually breaking rock into pieces

6. Mechanical Weathering: Unloading The uplift and weathering of rocks overlying igneous rocks Why? – Pressure on igneous rocks is reduced causing uplift Exfoliation: slabs of outer rock separate and break loose

7. Mechanical Weathering: Biological Activity Activities of living organisms Example: – Plant roots wedge into rocks, breaking them apart

8. What is Chemical Weathering? Is the transfer of rock into one or more new compounds

9. Agents of Chemical Weathering Water – Most important agent – Picks up gases from the atmosphere Oxygen – Causes oxidation of metal minerals – Ex: rusting Emissions – Carbon dioxide from respiration, sulfur dioxide and nitrogen oxides from burning fossil fuels – Combines with water in the atmosphere to form acids like in acid rain

10. Chemical Weathering in Action Granite – Minerals turn into clay – Washed away with water Spheroidal Weathering – Causes the corners and edges of rock to be rounded

11. Rate of Weathering What affects it? Rock Characteristics – Mineral composition – Mineral solubility Climate – Temperature and moisture – Favors high temperatures and abundant moisture

12. Surface area Surface area Topography (slope/gravity) Topography (slope/gravity)

13. Day 2 Objective Objective – I can explain the composition, structure and formation of soil

14. What is Soil? Part of the regolith that supports the growth of plants Regolith – Layer of rock and mineral fragments that cover most of Earth’s land surface

15. How is Soil Formed? Weathering of rocks that is carried away Factors – Parent Material – Time – Climate – Organisms – Slope

16. Soil Formation Factors Parent Material – Source of the mineral matter in the soil Time – Important in all geologic processes – The longer a soil has been forming, the thicker it becomes

17. Climate – Greatest effect on soil formation – Influences of temperature and precipitation affect rate, depth and type of weathering Organisms – Furnish organic matter in soil Slope – Steep slopes often have poorly developed soils

18. Characteristic of Soil: Soil Composition 45% mineral matter 25% air 25% water 5% humus – Decayed remains of organisms

19. Characteristic of Soil: Soil Texture Refers to the proportions of different particle sizes – Sand (large size) – Silt (feels like flour) – Clay (small size) – Loam (mix of all three; best for plants)

20. Soil Texture Triangle Percent Clay Percent Silt Percent Sand Texture Type 6020 40 102070

21. Characteristic of Soil: Soil Structure Clumping together of the particles

22. Day 3 Objective: Objective: – I can explain what erosion is – I can explain how erosion works

23. What is Erosion? Removal and transport of weathered material from one location to another

24. Agents of Erosion Running Water Wind Glaciers Ocean currents and Waves Biological Organisms

25. What happens to the Material? Deposition – Materials are dropped in another location – Final stage of erosion

26. How does Water Erode Soil? Rain uses gravity as a force to move soil down a slope

27. Process of Water Erosion 1.Sheet Erosion – Thin surface of water moving soil particles 2.Rills – Tiny streams 3.Gullies – Trenches Each move the soil a small distance

28. What is a Glacier? Large, moving mass of ice that forms near Earth’s poles and in mountainous regions at high elevations

29. How do Glaciers Erode Soil? Scrape and gouge out large sections of landscape Can carry huge rocks and piles of debris over great distance

30. Landforms Created by Glaciers Glaciated Valley – U-shaped valley Cirques – Bowl-shaped depression at the head of a glaciated valley, that is surrounded on three sided by steep rock walls Arêtes – Snaking ridge Horns – Pyramid-like peaks

31. How does Wind Erode Soil? Strong in areas of little vegetation cover Pick up and carry sediment These particles batter other structures

32. Landscapes Shaped by Wind Sand Dunes – Mounds or ridges of sand – Wind also can cause them to move Loess – Windblown silt that blankets the landscape

33. How can humans control erosion? Planting rows of trees called windbreakers Terracing hillsides Plowing along the contours of hills Rotating crops

34. Day 4 Objective: Objective: – I can explain the types of mass movements and what causes them – I can explain the hazard to humans they have and how to prevent them

35. What is Mass Movement? The transfer of rock and soil down-slope due to gravity

36. Triggers of Mass Movement Water – Heavy rain and rapid snow melting saturate the surface – Particles slide past one another easier Over-steepened Slopes – The steeper the slope, the greater the chance for movement

37. Removal of Vegetation – Roots keep soil intact – Removing plants increase chances of movement and erosion Earthquakes – Dislodge rocks and minerals

38. How to Classify Mass Movement? Classified by – Kind of material moved – How it moves – Speed of movement

39. Types of Mass Movement Rock falls Slides – Rockslides – Landslides Slumps Flows – Mudflow – Earthflow Avalanches Creep

40. Rock falls When rock or rock fragments fall freely through the air

41. Slides A block of material moves suddenly along a flat, inclined surface Rockslides – Include segments of bedrock Landslides – Movement of relatively thin block of loose soil, rock and debris

42. Slumps Downward movement of block of material along a curved surface

43. Flows Containing a large amount of water which moves downslope as a thick fluid Mudflow – Swiftly moving mixture of mud and water Earthflow – Moves relatively slow – Carry clay-rich sediment

44. Avalanches Extremely rapid movement of Earth material or snow

45. Creep Slow, downhill movement of soil Only noticeable over long period of time Slowest type of mass movement

46. Preventative Actions Dig series of trenches to divert running water Constructing protective fences on highways Retaining walls for weak slopes Don’t build on steep slopes