Weathering, Erosion and Soils

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2013 NC PPT for Academic and Honors Earth Science

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Weathering, Erosion and Soils

  1. 1. 3:00 Created by L. Zimmerman
  2. 2. Physical (AKA – Mechanical) – Chemical – Abrasion – Carbonation – Frost Wedging – Oxidation – Plants – Hydrolysis– Exfoliation - = the breaking of rock into smaller particles called sediment. Created by L. Zimmerman
  3. 3. Types of Weathering Mechanical (physical)–causes a rock to crack or break into pieces without changing it chemically
  4. 4. Physical (AKA – Mechanical) – Chemical – causes a rock to crack or break into pieces without changing it chemically Abrasion – Carbonation – Frost Wedging – Oxidation – Plants – Hydration – Exfoliation - = the breaking of rock into smaller particles called sediment. Created by L. Zimmerman
  5. 5. Physical Weathering  Abrasion  sediments carried by streams and wind blown sand cause particles to collide into each other and the surrounding rock. Created by L. Zimmerman
  6. 6. Physical (AKA – Mechanical) – Chemical – causes a rock to crack or break into pieces without changing it chemically Carbonation – Abrasion – Bump & Grind (streams/wind) smooth rounded particles Frost Wedging – Oxidation – Plants – Hydration – Exfoliation - = the breaking of rock into smaller particles called sediment. Created by L. Zimmerman
  7. 7. Physical Weathering Frost wedging  water seeps into the cracks in a rock and freezes causing the ice to expand. Created by L. Zimmerman
  8. 8. Created by L. Zimmerman
  9. 9. Physical (AKA – Mechanical) – Chemical – causes a rock to crack or break into pieces without changing it chemically Carbonation – Abrasion – Bump & Grind (streams/wind) Smooth, rounded particles Oxidation – Frost Wedging – water seeps into the cracks in a rock and freezes causing the ice to expand Hydrolysis– Plants – Acid Rain Exfoliation - = the breaking of rock into smaller particles called sediment. Created by L. Zimmerman
  10. 10. Physical Weathering  Plants  Trees and shrubs can grow through cracks in rocks. Their roots wedge into crevices.  Created by L. Zimmerman
  11. 11. Physical (AKA – Mechanical) – Chemical – causes a rock to crack or break into pieces without changing it chemically Carbonation – Abrasion – Bump & Grind (streams/wind) Frost Wedging – water Oxidation – seeps into the cracks in a rock and freezes causing the ice to expand Plants – roots wedge into rock and grow (expand) Hydrolysis– Exfoliation - Acid Rain - = the breaking of rock into smaller particles called sediment. Created by L. Zimmerman
  12. 12. Physical Weathering Exfoliation –cycle of heating and cooling causes the rock to expand & contract so it breaks off in slabs or layers. Created by L. Zimmerman
  13. 13. Created by L. Zimmerman
  14. 14. Physical (AKA – Mechanical) – Chemical – causes a rock to crack or break into pieces without changing it chemically Carbonation – Abrasion – Bump & Grind (streams/wind) Frost Wedging – water Oxidation – seeps into the cracks in a rock and freezes causing the ice to expand Plants – roots wedge into rock and grow (expand) Hydrolysis– Exfoliation – Freeze & Thaw causes rock to “peel” Acid Rain - = the breaking of rock into smaller particles called sediment.
  15. 15. Types of Weathering  Chemical – Any process that causes rocks to breakdown by chemical action and results in a change in the minerals (chemical composition). Created by L. Zimmerman
  16. 16. Physical (AKA – Mechanical) – Chemical – involves water + it changes the rocks chemical composition causes a rock to crack or break into pieces without changing it chemically Abrasion – Carbonation – Frost Wedging – Oxidation – Plants – Hydration – Exfoliation - = the breaking of rock into smaller particles called sediment. Created by L. Zimmerman
  17. 17. Chemical Weathering Carbonation – carbon dioxide in the atmosphere dissolves in the droplets of water that make-up clouds. This forms a weak carbonic acid. Carbonic acid reacts with certain rocks and minerals which include: calcite, limestone, marble and chalk. Created by L. Zimmerman
  18. 18. Physical (AKA – Mechanical) – Chemical – involves water + it changes the rocks chemical composition causes a rock to crack or break into pieces without changing it chemically Abrasion – Carbonation – CO2 + H2O form weak acid that dissolves limestone Frost Wedging – Oxidation – Plants – Hydrolysis– Exfoliation - = the breaking of rock into smaller particles called sediment. Created by L. Zimmerman
  19. 19. Chemical Weathering  Oxidation Water + Oxygen = Rust Created by L. Zimmerman
  20. 20. Chemical Weathering Hydrolysis Created by L. Zimmerman
  21. 21. Physical (AKA – Mechanical) – Chemical – involves water + it changes the rocks chemical composition causes a rock to crack or break into pieces without changing it chemically Abrasion – Carbonation – CO2 + H2O form weak acid that dissolves limestone Frost Wedging – Oxidation – Rust Plants – Hydration – Water dissolves mineral to clay Exfoliation - = the breaking of rock into smaller particles called sediment. Created by L. Zimmerman
  22. 22. Chemical Weathering  Acid Rain – Gases produced by humans can dissolve in the water droplets of a cloud to produce acid rain.  These acids include: H2SO4 – sulfuric acid  HNO3 – nitric acid
  23. 23. Cleopatra’s Needle Over 3,400 years old & made of limestone – Installed in London and NYC in 1880’s Photo shows before and after and effects of acid rain and rates of weathering!
  24. 24. Physical (AKA – Mechanical) – Chemical – involves water + it changes the rocks chemical composition causes a rock to crack or break into pieces without changing it chemically Abrasion – Carbonation – CO2 + H2O form weak acid that dissolves limestone Oxidation – Rust Hydrolysis – Water dissolves mineral to clay Acid Rain – pollution combines with water vapor produces weak acid that dissolves rocks. Frost Wedging – Plants – Exfoliation - = the breaking of rock into smaller particles called sediment.
  25. 25. Rates of Weathering SLOW FAST Climate Warm & Wet = fast chemical Cold & Wet = fast physical Temp & Moisture Rock Type Sedimentary Shale/siltstone – conglomerate - limestone Sandstone Dolostone Created by L. Zimmerman Cold/Warm & Dry Igneous & Metamorphic
  26. 26. Rates of Weathering Climate is the major factor that affects the rate of weathering
  27. 27. Rates of Weathering Due to climate and different weathering processes, landscapes develop differently. Arid Climate – angular, sharp edges, little vegetation
  28. 28. Rates of Weathering Humid Climate – soft, rounded with vegetation
  29. 29. Rates of Weathering Rock Types – cause softer, less resistant rocks to wear away, leaving harder, more resistant rocks behind. Limestone (A) is most resistant Shale (B) is least resistant Created by L. Zimmerman
  30. 30. Rates of Weathering Looking Glass Falls near Ashville shows differential weathering. Created by L. Zimmerman
  31. 31. Rates of Weathering SLOW FAST Above Ground Small size or more surface area TIME Particle Size Or Surface Area Created by L. Zimmerman Underground/lesstime Large size or less surface area
  32. 32. Rates of Weathering Particle Size – As a rock breaks into smaller pieces, the surface area increases, and therefore the rate of weathering increases.
  33. 33. Products of Weathering Solid Sediments Size by name and number Colloids • very small solid particles and too light to settle in water.
  34. 34. Products of Weathering Dissolved Minerals – cause the “hardness” in groundwater (and surface water).  It may mean calcium and lime deposits on your shower or if you have a well, sulfur and rust stains in the sink.
  35. 35. Chemical Weathering Carbonation – carbon dioxide in the atmosphere dissolves in the droplets of water that make-up clouds. This forms a weak carbonic acid. Carbonic acid reacts with certain rocks and minerals which include: calcite, limestone, marble and chalk.
  36. 36. Created by L. Zimmerman
  37. 37. Cave Details Created by L. Zimmerman
  38. 38. Carlsbad Cavern, New Mexico Created by L. Zimmerman
  39. 39. Rocks, Weathering, and Soil Formation Click for Clip
  40. 40. Soil Formation      Soil Profile Climate is one of the most important factors in formation of Soil. Soil Soil varies in composition, texture, structure, and color at different depths. These differences help divide the soil into zones known as Horizons. Horizons A side view of these horizons create a soil PROFILE. PROFILE
  41. 41. Soil Composition      O Horizon: organic matter that has fallen on the ground and is decaying A Horizon: topsoil (aka humus). This is the zone where surface water leaches into the layers below. B Horizon: subsoil (aka regolith). Layer immediately below the topsoil. This layer gets nutrients through the process known as LEACHING, when water flows through the topsoil and pulls nutrients down with it. C Horizon: partially weathered rock. This is the bottom layer of soil. Below it is solid bedrock.
  42. 42. Life in Soil   Some organisms mix the soil and make spaces in it for air and water. Other soil organisms make humus, the material that makes soil fertile.   Humus forms through decomposition. Fertile soil is rich in nutrients that plants need.
  43. 43. Soil Conservation  Soil is one of Earth’s most valuable resources because everything that lives on the land depends directly or indirectly on soil.  Fertile soil is valuable because there is a limited supply.  Less than 1/8th of the land on Earth has soils well suited for farming. farming
  44. 44. Soil Damage and Loss  Soil can become exhausted, or lose its fertility.  Accelerated Soil Erosion Unwise Clearing and Farming methods increase soil erosion. For example, clearing forests and containing animals to small pastures destroys the soil protection of plants 
  45. 45. Soil Lost To The Seas!!
  46. 46. Three Examples of Accelerated Soil Erosion:    Deforestation - ( clearing trees ) Gullying – furrows in plowed land which causes water  to run faster over the soil Climate Changes – excessive rain or wind Soil Conservation  Intercropping: crops planted in alternating bands Intercropping     Contour Plowing: soil plowed in circular motion with the Plowing lay of the land Terracing: step-like ridges in sides of hills Terracing Crop Rotation: planting one crop one year and a Rotation different one next year
  47. 47. Contour Plowing   Contour plowing is the practice of plowing fields along the contours of a slope. This helps slow the runoff of excess rainfall and prevents it from washing the soil away.
  48. 48. Conservation Plowing   Conservation Plowing disturbs the soil and its plant cover as little as possible. Dead weeds and stalks of the previous year’s crop are left in the ground to help return soil nutrients.
  49. 49. WATER GLACIERS •Scratched •Polished •U- shape valleys WIND •Arid Deserts •Dunes GRAVITY •#1 agent •Well sorted •Smooth •Rounded •Unsorted & loose Definition: - Transporting •Unsorted •Mass wasting •Creep •Slump •Talus or moving weathered sediments •Pitted/frosted Driving Force: GRAVITY Humans WAVES •Beaches •Longshore current •Jetties & Groins •Farming •Mining •Deforestation
  50. 50. Erosion by Gravity •The movement of SOIL particles and Rock fragments is called MASS Wasting. Wasting •TALUS : rock fragments that gather at the bottom of the slope. • Rapid Mass Movements • ROCKFALL: rocks falling from a steep cliff ROCKFALL •ROCK SLIDE: loose rock and soil moving down a slope SLIDE •MUD FLOW: rapid movement of mud FLOW •SLUMP: large block of soil moving downhill in one piece SLUMP Created by L. Zimmerman
  51. 51. Erosion by Gravity MUDSLIDE Created by L. Zimmerman
  52. 52. Erosion by Gravity Slump Talus Slope Created by L. Zimmerman
  53. 53. Erosion by wind Created by L. Zimmerman
  54. 54. Vertical Sorting – In a quiet body of water Loss of velocity Big gets dropped first Water Deposits •Well Sorted •Rounded •Smooth •Abrasion Horizontal Sorting – Stream enters lake Loses velocity Sediments deposited Big – close to shore Small – Far from shore Factors affecting Deposition: SIZE Velocity Shape Gradient Density Discharge Deposition The settling or dropping of particles after being picked up by an agent of erosion Wind works the same way
  55. 55. Deposition Size – As the size of sediment increases, the rate of deposition increases. Created by L. Zimmerman
  56. 56. Deposition Density – As the density of sediment increases, the rate of deposition increases. Shape – The flatter the particle the slower the deposition. Created by L. Zimmerman
  57. 57. Deposition As Velocity goes up – Erosion goes up and Deposition goes down As Gradient gets steeper – Erosion goes up and Deposition goes down As Discharge increases – Erosion goes up. up Created by L. Zimmerman
  58. 58. Deposition When a stream enters a body of water, its speed will decrease, and therefore the deposition of sediments occurs. A deposit at the mouth of a stream where it enters a large body of water is called a delta.
  59. 59. Deposition A delta is an example of the horizontal deposition of sediments in the water. Boulders Cobbles Evidence of Sorted Sediment Pebbles Clay Created by L. Zimmerman
  60. 60. Wind Deposits Velocity = FAST - Erosion •Similar to water •Loss of velocity will result in deposition by size •Well sorted •Graded bedding Velocity = Slow - Deposition Created by L. Zimmerman
  61. 61. Erosional/Depostional Systems YOUNG RIVERS V shaped valley Fast Steep Straight Rapids & Waterfalls MATURE Medium slope Slight curves Medium speed Narrow floodplain Small rapids OLD Flat Slow Lots of meanders Straight Wide floodplain & Channel
  62. 62. Erosional/Depositional Systems - Rivers Created by L. Zimmerman
  63. 63. Erosional/Depositional Systems - Rivers The bends in a stream’s channel are called meanders Created by L. Zimmerman
  64. 64. Erosional/Depositional Systems - Rivers Arial Map View of a stream Channel Created by L. Zimmerman
  65. 65. Erosional/Depositional Systems - Rivers Outside of the curve= velocity increase = more erosion. Inside of the curve= velocity decrease = deposition. Created by L. Zimmerman
  66. 66. Erosional/Depositional Systems - Rivers Erosion Deposition Created by L. Zimmerman
  67. 67. Erosional/Depositional Systems - Rivers Formation of Oxbow Lake – the work of erosion and deposition Created by L. Zimmerman
  68. 68. Erosional/Depositional Systems - Glaciers  Glaciers can really move a lot of material, material dramatically changing the surface of the earth.  2 Types:  Continental – covered North America over 10,000 years ago and is the cause of finger lakes and Morraines (like Long Island)! Alpine – in mountains   Created by L. Zimmerman Create U-Shaped valleys
  69. 69. Erosional/Depositional Systems - Glaciers Created by L. Zimmerman
  70. 70. Erosional/Depositional Systems - Glaciers Continental Glacier Moved from the north (pole) to the south GLACIERS Features: Unsorted, loose deposits Ground up rock flour or glacial till Moraines U-shape Valleys Kettle lakes, drumlins, outwash plains Move downhill! Alpine Glacier Created by L. Zimmerman
  71. 71. Erosional/Depositional Systems - Glaciers  Glacial Features A. Terminal Moraine Lateral Moraine Glacial stream Outwash plains Braided streams U- Shaped Valleys B. C. D. E. F. Created by L. Zimmerman
  72. 72. Erosional/Depositional Systems - Glaciers Post - Glaciation During Glaciation Its a U shape valley! Created by L. Zimmerman
  73. 73. Drumlins Created by L. Zimmerman
  74. 74. Formation of Finger Lakes Formation of Long Island Created by L. Zimmerman
  75. 75. Landscape Development  How is the Earth’s surface shaped by weathering, erosion and deposition? Created by L. Zimmerman
  76. 76. Landscape Development  Landscape: A region on the Earth’s surface in which physical features, such as hills, valleys, and streams are related by a common origin (it simply means “scenery”)  Three (3) main types: Mountains, Plains and Plateaus Created by L. Zimmerman
  77. 77. Landscape Development Mountains  Greatest relief between their peaks and valleys  Created by tectonic forces (igneous and metamorphic rocks)  Steep mountain slopes have fast erosive streams acting on them, creating deep valleys and waterfalls Created by L. Zimmerman
  78. 78. Landscape Development Plateaus    Low relief (flat) High elevation Horizontal rock formations NC Piedmont Created by L. Zimmerman
  79. 79. Landscape Development    Plains (lowlands) Have the least relief Generally flat and low elevations Underlain by flat layers of sedimentary rock Created by L. Zimmerman
  80. 80. Tectonic Forces LANDSCAPE Crustal Materials DEVELOPMENT Climate ARID Humans Humid Time

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