1. Weathering

2. Weathering
the process that produces change in the surface of rocks exposed to the atmosphere and/or hydrosphere.

3. Two Types OF Weathering:
Physical weathering is breaking rock by force.
ex: hitting, scratching, cracking
Chemical weathering is where the rock material is changed into another substance by reacting with a chemical.

4. Frost action (ice wedging)- Water seeps into small cracks in rocks.
When the water freezes it expands creating great pressure.
The crack widens and allows water to seep deeper into the rock.

5. Biological Activity Plant action-
Tiny root hairs seek out small cracks and pits in rock.
Once the root hairs find a place they grow and expand.
The expansion causes great pressure and cracks the rock.

6. Unloaded  Exfoliation
Rocks formed deep in the Earth are made under high pressure.
When the pressure is released the rocks expand & crack.
May also be caused by alternate heating and cooling of rocks by weather conditions.

7. Chemical Weathering Oxidation-
Oxygen in the atmosphere chemically reacts with minerals.
ex.: rusting of a nail
Water **** MOST IMPORTANT !!!!!
Minerals are dissolved in water.
ex.: Halite, calcite

8. Acid- Carbonic acid:
C02 dissolves in rain water forming a weak acid
Acid Rain: Sulfur Dioxide in the atmosphere dissolves in rain water forming a strong acid (sulfuric acid).

9. Chemical Weathering

10. Chemical Weathering

11. Ex. Of Chemical Weathering

12. Rates of weathering will be influenced by:
Surface area exposed -
weathering occurs on the surface. More surface exposed, the faster the weathering will occur.

13. A smashed piece has greatest surface area exposed
A smashed piece has greatest surface area exposed. The interior can now be attacked.
A full, solid block has the least surface area. The interior is safe from exposure.

14. Rates of Weathering will depend on:
Mineral composition- some minerals are more resistant than others.
ex.:Quartz is resistant to chemical and physical weathering.

15. Rates of Weathering will depend on:
Climatic Conditions:
Cold and/or dry climates favor physical weathering.
Warm and wet climates favor chemical weathering.
Frost action works best in areas where the temperature fluctuates wildly.

16. Soil - The product of weathering
Soil- rocks, minerals (mainly sand and clay), and organic material (regolith and organic matter)
Soil forms layers of different characteristics called horizons.

20. What are the main components of soil?
Mineral Matter
Air
Water
Organic Matter

22. What are the FACTORS that make SOIL?
TIME
1000’S TO 10,000’S OF YEARS
LAY OF THE LAND / “SLOPE”
TOPOGRAPHY
LIVING ORGANISMS
ANIMALS AND PLANTS
CLIMATE
HOT/COLD, WIND/RAIN
PARENT MATERIAL
ROCKS AND MINERALS

23. Topography
Physical land features

24. Why is soil important ?
Necessary for the growth of rooted plants which support our life system !!!!

25. Erosion
Movement of sediments (soil) from one location and deposition of it another place.
Can occur in 2 ways

26. 2 ways erosion can occur ….
Earth processes which move material on the Earth’s surface over long periods of time, such as weathering and gravity
Human activity which moves material on the Earth's surface over short periods

27. Transport Agents of Erosion
Water
Rain
Streams and rivers
Ocean
Ice (glaciers)
Wind
Gravity

28. Rain drop erosion

29. Erosion by Water

30. Rill Erosion

31. Erosion by Wind

32. Erosion due to gravity 

33. Example of Human Made Erosion

34. Erosion at Construction Site

35. Silt fencing during construction doesn’t necessarily stop all erosion

36. Vegetation protects soil

37. My Neighbor has my soil!

38. How Erosion Effects the Environment

39. #1 Pollutant to our Waters

40. Sedimentation in Rivers
pollutes water with soil particles
damages water ecosystems through reduced sunlight for aquatic plants and animals
increases water treatment costs for human water consumption
reduces the depth of rivers, thus creating waterways that can't be navigated by commercial crafts

41. Wind Erosion removed topsoil

42. Removal of topsoil from land areas
prevents plant growth
alters ecosystems, thus reducing the biodiversity of life
destroys crops
reduces agricultural food production
reduces farming income

43. The Great Dust Bowl
Wind Erosion

44. Wind Erosion increases the amount of particles in the air
reduces visibility
reduces air quality
causes breathing problems (asthma, etc.)

45. What can help prevent erosion?

46. Plants can help prevent erosion. Look at the roots on these grasses
Plants can help prevent erosion! Look at the roots on these grasses. Roots help hold the soil in place so that it doesn’t wash away.
Plant roots

47. Mass Movement
The transfer of rock and soil downslope due to gravity

48. Triggers of Mass Movement
Saturation of material with water
Oversteepened slopes
Removal of vegetation
Earthquakes

49. Types of Mass Movements
Based on:
Kind of material that moves
How it moves
Speed of movement

50. Rockfalls
Usually happens on oversteepened slopes due to mechanical weathering (freeze-thaw)

51. Slides Occur suddenly and can reach speeds of over 200 km/hr
Usually occur in the mountains

52. Slumps
Do not occur suddenly
Usually happens in clay soil

53. Flows Contains a large amount of water Mudflows – move quickly
Earthflows - slower

54. Creeps Occur gradually over time
Usually due to freezing and thawing of soil

55. The End
Chapter 5