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Review: Weathering and Erosion. What is Mechanical Weathering ?

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Presentation on theme: "Review: Weathering and Erosion. What is Mechanical Weathering ?"— Presentation transcript:

1 Review: Weathering and Erosion

2 What is Mechanical Weathering ?

3 When physical forces break rock into smaller pieces Does not change the rock’s composition Three Ways – Frost Wedging – Unloading – Biological Activity

4 Mechanical Weathering: _________________?

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: _________________? The uplift and weathering of rocks overlying igneous rocks Why? – Pressure on igneous rocks is reduced causing uplift ____________?: slabs of outer rock separate and break loose

7 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

8 Mechanical Weathering: _________________? Activities of living organisms Example: – Plant roots wedge into rocks, breaking them apart

9 What is Chemical Weathering?

10 Is the transfer of rock into one or more new compounds

11 Agents of Chemical Weathering _________? – Most important agent – Picks up gases from the atmosphere _________? – Causes oxidation of metal minerals – Ex: rusting _________? – 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

12 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

13 Rate of Weathering What affects it?

14 Rock Characteristics – Mineral composition – Mineral solubility Climate – Temperature and moisture – Favors high temperatures and abundant moisture

15 Surface area Surface area Topography (slope/gravity) Topography (slope/gravity)

16 How is Soil Formed?

17 Weathering of rocks that is carried away Factors – Parent Material – Time – Climate – Organisms – Slope

18 Soil Texture Triangle Percent Clay Percent Silt Percent Sand Texture Type

19 What is Erosion?

20 Removal and transport of weathered material from one location to another

21 Agents of Erosion?

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

23 What happens to the Material? _________? – Materials are dropped in another location – Final stage of erosion

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

25 What is a Glacier?

26 Large, moving mass of ice that forms near Earth’s poles and in mountainous regions at high elevations

27 How do Glaciers Erode Soil?

28 Scrape and gouge out large sections of landscape Can carry huge rocks and piles of debris over great distance

29 How can humans control erosion?

30 Planting rows of trees called windbreakers Terracing hillsides Plowing along the contours of hills Rotating crops

31 What is Mass Movement?

32 The transfer of rock and soil down-slope due to gravity

33 Triggers of Mass Movement

34 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

35

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

37 How to Classify Mass Movement? Classified by:

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

39 Types of Mass Movement

40 Rock falls Slides – Rockslides – Landslides Slumps Flows – Mudflow – Earthflow Avalanches Creep

41 Preventative Actions

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

43 The Hydrosphere

44 Distribution of Water On Earth

45 71% of Earth is water – 97% in the oceans – 3% is freshwater 2% in ice and glaciers 0.6% in underground water 0.4% in rivers, streams, lake and atmosphere

46 Parts of the Water Cycle A.__________? liquid water changes into water vapor B.__________? liquid or solid water from the clouds C.__________? water vapor that turns into liquid making clouds D.__________? liquid water moving through the ground E.__________? water vapor released to the air by plants F._______? when liquid hit the ground but not absorbed

47 Parts of the Water Cycle A.Evaporation: liquid water changes into water vapor B.Precipitation: liquid or solid water from the clouds C.Condensation: water vapor that turns into liquid making clouds D.Infiltration: liquid water moving through the ground E.Transpiration: water vapor released to the air by plants F.Runoff: when liquid hit the ground but not absorbed

48 The Water Cycle

49 How is Water Used? 70% in ______? 20% in ______? 10% in ______?

50 How is Water Used? 70% in Irrigation 20% in Industries 10% in Cities and Residences

51 How do Currents Influence Climate?

52 Exchanges heat in the water with the atmosphere Type of current nearby influences weather for an area – Warm currents bring warm temperatures – Cold currents bring cooler temperatures

53 Current Movement Warm Currents: ________________ Cold Currents: ________________

54 Current Movement Warm Currents – Move from the tropics to the poles – Ex: Gulf Stream (east coast of the US) Cold Currents – Move from the poles to the equators – Ex: Canary Current

55 Why do Current Moves? Primary Forces? Secondary Forces?

56 Why do Current Moves? Primary Forces – Start the movement – Solar heating, winds, gravity, Coriolis Secondary Forces – Influences where the current flows

57 How does water become Groundwater? _____________? – How easily water can pass through connected pore spaces ___________? – Percentage of pore spaces in soil and rock – Clay has the smallest percentage (not permeable)

58 How does water become Groundwater? Permeability – How easily water can pass through connected pore spaces Porosity – Percentage of pore spaces in soil and rock – Clay has the smallest percentage (not permeable)

59 Groundwater Layers A.________________? – Area above the water table where water passes through B.________________? – Area where the soil, sediment and rock are saturated with water C.________________? – The upper level of the zone of saturation D._______________? – The water within the zone of saturation

60 Groundwater Layers A.Zone of Aeration – Area above the water table where water passes through B.Zone of Saturation – Area where the soil, sediment and rock are saturated with water C.The Water Table – The upper level of the zone of saturation D.Groundwater – The water within the zone of saturation

61 Aquifers

62 Underground layer of water bearing permeable rock (gravel, sand or silt) from which ground water can be extracted using a well

63 Wells A hole bored into the zone of saturation Pumping can cause the water table to be lowered Artesian Well?

64 Wells A hole bored into the zone of saturation Pumping can cause the water table to be lowered Artesian Well – Groundwater rises on its own under pressure

65 Problems with Groundwater?

66 Problems with Groundwater Withdrawing water for agriculture Toxic metals contaminating the water (arsenic, cadmium, lead) Salt water intrusion – Salt water from the ocean enters the groundwater near coastal areas

67 A Stream’s Profile A.___________? – At the beginning of a stream – Usually at the mountains or higher elevations B.__________? – At the end of a stream – Usually at the ocean or another water body C._________? – A stream that empties into another stream

68 A Stream’s Profile A.Headwater – At the beginning of a stream – Usually at the mountains or higher elevations B.Mouth – At the end of a stream – Usually at the ocean or another water body C.Tributary – A stream that empties into another stream

69 Watershed?

70 Watershed An area of land that contains a common set of streams and rivers

71 Drainage Basins?

72 Drainage Basins Is the land area that contributes water to a stream

73 Results of Floods _____________? – Area where water floods the land Provides a supplement of nutrient-rich silt to floodplain areas Recharges groundwater Kills and causes property damages

74 Results of Floods Floodplain – Area where water floods the land Provides a supplement of nutrient-rich silt to floodplain areas Recharges groundwater Kills and causes property damages

75 How to control Floods? _______________? – Concrete or Earthen mounds built on the banks of a river – Increases the amount of water it can hold _______________? – Parallels a stream and helps to contain its water, except during flood stage

76 How to control Floods? Artificial Levees – Concrete or Earthen mounds built on the banks of a river – Increases the amount of water it can hold Natural Levees – Parallels a stream and helps to contain its water, except during flood stage

77 ____________? – Stores floodwater and lets it out slowly ____________? – Preserve floodplains instead of building on them

78 Flood-Control Dams – Stores floodwater and lets it out slowly Limit Development – Preserve floodplains instead of building on them

79 Human Activities Causing Flooding Removing vegetation Overgrazing Mining Building on floodplains Logging Forest fire Destruction of wetlands Urbanization

80 Human Activities Causing Flooding Removing vegetation Overgrazing Mining Building on floodplains Logging Forest fire Destruction of wetlands Urbanization

81 Types of Water Pollution __________________? – Organic waste and manure _______________? – Acids, arsenic, lead ________________? – Nitrogen and phosphorus ________________? – Oil, detergents, pesticides _______________? – Erosion and soil

82 Types of Water Pollution Oxygen Demanding Agents – Organic waste and manure Toxic Metals – Acids, arsenic, lead Inorganic Plant Nutrients – Nitrogen and phosphorus Organic Chemicals – Oil, detergents, pesticides Sediment – Erosion and soil

83 Oxygen Demanding Agents __________? is removed from water by bacteria (B.O.D) Fish can’t live in streams without _________?

84 Oxygen Demanding Agents Oxygen is removed from water by bacteria (B.O.D) Fish can’t live in streams without oxygen

85 _______________? #1 source of water pollution Clouds the water Blocks sunlight for the aquatic plants

86 Sediment #1 source of water pollution Clouds the water Blocks sunlight for the aquatic plants

87 Protecting The Water __________________? – Regulates the discharge of pollutants in the US river and streams __________________? – Protect the quality of drinking water – Water treatment plants – Well water

88 Protecting The Water Clean Water Act (1972) – Regulates the discharge of pollutants in the US river and streams Safe Drinking Water Act (1974) – Protect the quality of drinking water – Water treatment plants – Well water

89 Water Conservation Methods

90 Repair leaking faucets and pipes Landscape using plants requiring little water Use drip irrigation Use water saving appliances Purify and reuse water


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