1. Weathering, Erosion and Deposition Ms. Sauer

2. Weathering, Erosion, and Deposition Weathering – the breakdown of rocks into smaller pieces, called sediments. Erosion – the process where the sediments are transported by wind, gravity, glaciers, man, and running water. Deposition – the process whereby these sediments are released by their transporting agents (dropped). Weathering breaks down the rocks, erosion moves the particles, and deposition drops the sediments in another location.

3. What is Weathering? The Chemical and Physical Breakdown of rocks on or at Earth’s Surface into smaller fragments Weathering Occurs when rocks are exposed to the hydrosphere or atmosphere. http://www.youtube.com/watch?v=LS0GDLP8oIo&feature=related

4. What are atleast three examples of weathering?

5. Weathering Physical / Mechanical –Frost Action –Abrasion –Exfoliation –Plant & Animal Chemical –Oxidation –Hydration –Carbonation (including Sink Holes, Karst Topography, Stalactites, & Stalagmites) –Organic Decay

6. Mechanical/ Physical Weathering When rocks are physically cracked, split, or broken into smaller pieces known as SEDIMENTS. Rock’s chemical makeup stays the same. Physical Weathering is Common in Mid-Latitude Climates where freezing and thawing occurs COLD & MOIST climates produce more mechanical weathering

7. Types of Mechanical Weathering 1) Frost Action- breakup of rocks caused by alternating freezing and thawing of water. Very common in Cold, Wet Climates

8. Ice/Frost Wedging/Action Frost action is the breakup of rocks caused by alternate freezing and thawing of water. Water condenses or seeps into the smallest cracks or spaces in rock as well as larger openings. When the water freezes, it expands, forcing the rock grains apart. When ice melts, the rock is more porous than before. Repeated freezing and expanding of water in these spaces will cause the rock to crumble into smaller pieces. Physical Weathering:

9. Frost Wedging Physical Weathering:

10. Frost Action

11. Frost Wedging

12. 2 nd Type 2) Abrasion- physical wearing down of rocks as they rub or bounce against one another. Dry, Windy Areas Common under glaciers, and in stream channels

13. Abrasion The physical wearing down of rocks as they rub or bounce against each other. Abrasion is most important in dry windy areas, under glaciers, or in stream channels. Physical Weathering:

14. Abrasion Mojave Desert, CA ABRASION - A physical erosion process, the wearing down of rock particles by friction due to constant scratching. Where solid particles are moved across a solid surface with the help of wind or water. Valley of Fire, Nevada Physical Weathering:

15. Glacial Abrasion in Bedrock Source: Tom Bean

16. Abrasion Physical Weathering:

17. 3 rd Type Exfoliation- the peeling away of large sheets of loosened material at the surface of a rock

18. Exfoliation The peeling away of large sheets of loosened material at the surface of a rock. Physical Weathering:

19. Exfoliation

20. 4 th Type Plants/ Animals- plant roots growing through the rocks and breaking them up. Ants, earthworms, and other small animals burrowing into cracks breaking rocks down further.

21. Root/Plant Wedging/Action Large shrubs and trees growing through cracks in boulders may break the rocks apart. Smaller plants that grow on rocks, such as lichens and mosses, wedge their tiny roots into pores and cracks, splitting the rock as they grow. Ants, earthworms and other burrowing animals digging holes in the soil break it down further. Physical Weathering:

22. PLANT ROOTS Physical Weathering:

23. Animal Action (Burrowing) Physical Weathering:

24. What type of mechanical weathering? Abrasion

25. What type of Mechanical Weathering? Exfoliation

26. What type of Mechanical Weathering Frost Action

27. How did this rock get this way? Abrasion

28. What happened to this road? Frost Action

29. How did this happen? Plant & Animal

30. Chemical Weathering Rock is broken down by chemical action, which results in a change in the composition of the rock. Intense in warm, moist climates Minerals in the rock change New minerals created by chemical reaction WARM & MOIST climates produce more chemical weathering http://www.youtube.com/watch?v=Sw58a4yjFtc

31. 2. Chemical Weathering – the breakdown of rocks and minerals into smaller pieces by chemical action. The rocks breaks down at the same time as it changes chemical composition. The end result is different from the original rock. There are 4 types of chemical weathering:

32. 1. Oxidation – oxygen combines with the elements in the rock and it reacts. This the scientific name for rust. 2. Hydration – water can dissolve away many earth materials, including certain rocks. 3. Carbonation – carbon dioxide dissolves in water to form carbonic acid. This makes acid rain which chemically weathers (dissolves) rocks. Other acids also combine with water to make acid rain. 4. Organic Decay – occurs when acids, which are formed when plants and animals decay, dissolve in water. The acid solutions dissolve rock minerals much the same way as in carbonation. Chemical Weathering:

33. Types of Chemical Weathering 1) Oxidation- Oxygen uniting chemically with minerals. Oxygen and Iron (Fe)- Create Rust

34. Oxygen Iron combines with oxygen in the presence of water in a processes called oxidation. The product of oxidation is rust. Chemical Weathering:

35. Oxidation Chemical Weathering:

36. 2 nd Type of Chemical Weathering 2) Water / Hydration Water weathers rock by dissolving it.

37. 3 rd Type of Chemical Weathering 3) Carbonation- CO 2 unites chemically with minerals When CO 2 is dissolved in water it forms weak carbonic acid. Carbonic Acid dissolves large masses of limestone. This creates caves, caverns, and other structures in bedrock. Sinkholes- CO 2 Acid dissolves limestone creating Karst Topography

38. Carbon Dioxide CO 2 dissolves in rain water and creates carbonic acid. Carbonic acid easily weathers limestone and marble. Chemical Weathering:

39. Acid Rain Compounds from burning coal, oil and gas react chemically with water forming acids. Acid rain causes very rapid chemical weathering. Chemical Weathering:

40. Carbonation Sink Holes – saucer-shaped holes on the surface of the land are left when carbonic acid dissolves limestone in the ground. A limestone area pitted with sink holes is called Karst Topography. In caves, the carbonic acid solution containing the dissolved limestone drips from the roof of the cave. Evaporation leaves limestone deposits on the ceiling and floor. The icicle-like deposits that “grow down” from the ceiling are called stalactites. Those deposits which “grow up” from the ground are called stalagmites. Chemical Weathering:

41. Sink Holes Chemical Weathering:

42. Sink Holes Devil’s Throat, Nevada Chemical Weathering:

43. Sink Holes Chemical Weathering:

44. Carbonation causing a sink hole

45. Guatemala City, June 2010 More than 100 deaths, approx 200ft deep

47. Karst Topography A type of landscape created by chemical weathering of limestone Located in rainy regions where there is limestone near the surface, characterized by sinkholes and caves. Chemical Weathering:

48. Karst Topography

49. Stalactites “grow down” Chemical Weathering:

50. Stalagmites “grow up” Chemical Weathering:

51. 4 th Type of Chemical Weathering Organic Decay- acids from dead plants and animals dissolve rock.

52. Living Organisms Lichens that grow on rocks produce weak acids that chemically weather rock. Chemical Weathering:

53. 2. Particle Size – Larger particles weather slower and smaller particles weather at a faster rate. There are 4 factors that effect the rate of weathering: 1.Surface Area (exposure) - Exposing more surface area will increase the rate of weathering. 3. Chemical Composition (what a rock is made of) – Certain rocks and minerals are naturally weaker than others, while others are more resistant (stronger). 4. Climate – Warmer, moister climates have the most weathering. Heat & Water speed up all chemical reactions. This is the most important factor in weathering.

54. 1 & 2) Particle Size and Surface Area The weathering rate of rock material varies inversely with particle size. In equal quantities of the same rock, the smaller the particles, the greater the weathering rate – the faster the particles weather. This rate difference occurs because the total surface area of the smaller particles is greater than the total surface area of the larger particles. Larger, solid pieces of rock weather more slowly than do smaller, loose pieces of the same rock.

55. 1 & 2) Particle Size and Surface Area Particle Size- Smaller the Particle Size the faster the weathering. Smaller particles have a greater surface area.

56. 1) Surface Area

57. 3) Mineral Composition & Amount of Weathering: Rock particles weather at different rates depending on their mineral composition. Because the hardness of minerals differs, different minerals have different resistances to weathering. Hard rocks weather more slowly than soft rocks.

58. 3) Mineral Composition & Amount of Weathering: Mineral Composition- Hardness of minerals differ, minerals have different resistances to weathering. Harder the rock the slower it weathers

59. 4) Climate Weathering of rocks occurs at a faster rate in humid climates than it does in dry climates. This is explained by the fact that most weathering agents – frost action, carbonation, organic decay, etc. – require, or are more effective in the presence of moisture.

60. Climate and Weathering Climate Conditions and Types of Weathering: Physical weathering is more pronounced in moist climates, where the wide range of temperatures cause alternate freezing and thawing. Chemical weathering is more intense in warm, moist climates. The amount of moisture available is the key factor in weathering. Usually, the more moisture available, the more weathering occurs.

61. What type of weathering occurs in an area that has an average of 165 cm of rain each year and an average temperature of 18°C? What type of weathering occurs in an area that has about 140 cm of precipitation each year and an average temperature of 5°C? strong chemical moderate chemical with frost action

62. Disappearing Lake http://www.youtube.com/watch?v=dHol4IC eDoohttp://www.youtube.com/watch?v=dHol4IC eDoo

63. What is Erosion? Erosion – Movement of weathered material from one place to another.

64. What are the major causes of erosion?

65. Factors of Erosion & Characteristics of Transported Sediment: 1.Gravity – moves small & large particles; unsorted. 2.Wind – moves small particles; sorted. 3.Running Water – moves small & large particles; sorted; smooth & round. 4.Glaciers - moves small & large particles; unsorted. 5.Waves / Beaches - moves small particles; sorted.

66. 1 st Factor of Erosion: Gravity – moves small & large particles. - unsorted deposition. - pulls rocks down slopes. - causes particles to be angular.

67. GRAVITY

68. Gravity: Gravity is the primary driving force behind all transporting (erosional) systems. Gravity provides each agent (running water, glaciers, or winds) with enough kinetic energy to transport sediments.

69. Avalanche

70. Mudslides

71. Landslides

72. Videos: Avalanche video: http://www.youtube.com/watch?v=B0RWLxOFG LY http://www.youtube.com/watch?v=B0RWLxOFG LY Mudslide Video: http://www.youtube.com/watch?v=51C7vEAVbx k http://www.youtube.com/watch?v=51C7vEAVbx k Landslide Video: http://www.youtube.com/watch?v=mknStAMia0Q http://www.youtube.com/watch?v=mknStAMia0Q

73. Mount Rushmore There is a pile of weathered material at the bottom. It is slowly being eroded down hill by gravity. It will not be there forever!! ***However, maintenance is done to maintain it***

74. You can identify which agent of erosion transported each sediment by looking at a few characteristics : Gravity – sediments that are transported by gravity are found in piles at the bottom of cliffs or steep slopes. They appear angular and unsorted.

75. 2 nd Factor of Erosion: Wind – moves small particles. - stronger the wind, bigger the sediment ( FAST= carries more). - sorted deposition of sediment. - Carries loose rocks through air & scrapes at other rocks - Causes particles to be frosted or angular.

76. Wind Erosion

80. Wind: The greater the velocity of wind, the larger the particles it can carry. Although erosion by wind is generally thought of as occurring in deserts or along beaches, dust storms can occur inland following long periods of drought.

81. You can identify which agent of erosion transported each sediment by looking at a few characteristics : Wind - sediments that have been transported by wind appear pitted (random holes) and frosted (glazed look) and are deposited in sorted piles. Only very small particles can be transported by wind.

82. 3 rd Factor of Erosion: Glaciers – A moving mass of ice - unsorted - moves small & large particles. –Picks up and drags rock- grinds across other rocks –Digs into land, widens valleys

83. Glaciers New Zealand

84. You can identify which agent of erosion transported each sediment by looking at a few characteristics : Glaciers – sediments that have been transported by glaciers appear scratched, grooved, and are deposited in completely unsorted piles, because they were dropped during melting. Also, boulders can only be transported by glaciers.

85. 4 th Factor of Erosion: Running Water – moves small & large particles - faster water moves, bigger the sediment ( FASTER= carries more) - smooth & round - sorted Three Ways Rivers Carry Sediment: 1.Rolling or Bouncing Along the Bottom 2.Suspension – floating 3.Solution - dissolved

86. Running Water

88. Running Water: Running water is the primary agent of erosion on Earth. Most running water is found in rivers or streams.

90. You can identify which agent of erosion transported each sediment by looking at a few characteristics : Running Water – sediments that have been transported through running water appear rounded and smooth and are deposited in sorted piles.

91. 5 th Factor of Erosion: Waves / Beaches - moves small particles - sorted deposition –Crashing waves chip away at rocks –Abrasion forms cliffs, arches and caves

92. Wave Erosion

94. Video: Smith’s Point Beach Erosion Video: http://www.youtube.com/watch?v=B24JIhi 7Nlc http://www.youtube.com/watch?v=B24JIhi 7Nlc

97. Effects of Humans on Erosion: Humans add to the erosion of the land through individual and societal activities. The natural processes of erosion can take a very long time; human activities can erode the land almost overnight (earth moved for roadways / railroad; surface exposed to erosion by wind or running water). Human activities contribute more than ever before to the erosion of Earth’s surface.

98. There are 5 ways that man can cause erosion: 1.Forestry – all vegetation of removed, and without roots, the soil will erode away. 2.Strip Mining – removing rock cover to get to the resources below, which causes the loose sediments to erode away. 3.Construction – the clearing of land to build buildings/houses also causes all loose soil to erode away. 4.Improper Farming – not plowing the land at right angles to slopes causes soil to erode away. 5.Salting Highways – the salt is washed off the road to the sides, where it prevents vegetative growth along the sides.

99. What is Deposition? Deposition – Eroded rock particles are dumped off or deposited in a new location http://www.youtube.com/watch?v=AE771AdF5dM

100. DEPOSITION Mississippi Delta DEPOSITION - When the carrying power of an erosional agent (wind, water, gravity, glaciers) decreases. Particles being carried will be dropped or deposited in a process called sedimentation.

101. DEPOSITION Dissolved minerals fall out of the solution when water evaporates. This depositional process is called precipitation.

102. Salt Farming

103. 4 Factors that affect Deposition Rate 1. Particle Size – all other factors being equal, larger particles settle more quickly than smaller particles. The smaller the particle (clay, silt) the slower it will settle out. Larger sediments (cobbles, boulders) will settle quickly.

104. 2nd Factor that affects Deposition Rate 2. Particle Shape - All other factors being equal, smooth, spherical particles settle faster than angular, flatter particles. Why is this?

105. Answer Friction is decreased when a particle is rounded and therefore it settles faster. It’s like it’s more aerodynamic - like a sports car. But in this case, it’s hydro-dynamic.

106. 3rd Factor that affects Deposition Rate 3. Density - If two particles have the same basic size and shape, the denser particle will settle faster. Which will settle faster – a glass marble or a lead marble? (they are both the SAME SIZE)

107. 4th Factor that affects Deposition Rate 4. As the stream slows down, the larger particles settle first

108. Silt particles are very small, slow moving water can carry it.

109. Sorting of Deposited Particles

110. Horizontal Sorting Final deposition of particles (sediments) at the mouth of a stream. This is due to the faster flowing stream emptying into a slower larger body of water. The sediments that were once carried down the stream are arranged from largest to smallest.

112. Horizontal Sorting – a situation where moving water enters a larger, still body of water slowly, and causes the larger particles to be deposited closer to the shoreline. Particle size decreases as you move away from the shore.

113. Delta – a fan shaped deposit that forms at the mouth of a river/stream when it enters a larger body of water. This is seen under the water. The particles are horizontally sorted.

114. Horizontal Sorting

115. Nile River Delta, Egypt

116. Vertical Sorting Happens in QUIET WATER (still – lake, pond) Particles sort out from bottom to top in layers On bottom – largest, roundest, densest particles On top – smallest, flattest, least dense particles Can occur when a depositional event, like a landslide, dumps a large volume of unsorted sediments into a still body of water like a lake It creates “graded beds” of sediments http://www.youtube.com/watch?v=3CavQ1o-CSchttp://www.youtube.com/watch?v=3CavQ1o-CSc (0:33)

117. Graded Bedding/Vertical Sorting – a situation where larger particles settle on the bottom and smaller particles settle towards the top. This happens naturally when a fast moving river/stream meets a large standing body of water. This happens because the velocity of the water decreases very quickly. (A waterfall emptying into a lake)

118. Graded Bedding One depositional event

119. Alluvial Fan - a fan shaped deposit of sediments that forms when a stream/river flows out of a mountain on to flat, dry plains. These are not under water and are very visible. This only happens on the land. You can call it a “land delta”.

120. Graded Bedding One depositional event

121. CROSS BEDDING Layers of sediments deposited at angles. The angle shows the direction of movement. (wind and water erosion is responsible for most cross bedding)

123. Cross-Bedding – a situation where layers of sediments are deposited at angles to one another as a result of a change of direction of the erosional agent. These are usually found in sand dunes, deltas, and alluvial fans.

124. (3) Deposition

125. (3) Glacial deposits are unsorted, and river deposits are sorted.

126. (4) Bigger particles are generally deposited first.

127. (2) The rate of deposition is greater than the rate of erosion.

128. (1) 50 cm/sec

129. (4) Running Water

130. (a)The velocity decreases(b) Clay

131. Erosion and Deposition Erosion Deposition Movement of weathered material from one place to another. Eroded rock particles are dumped off or deposited in a new location

132. Erosion and Deposition WindHow does it erode? How does it deposit? –Carries loose rocks through air- scrapes at other rocks –FAST= carries more –When it slows down, dumps off rocks to form dunes/piles

133. Erosion and Deposition GravityHow does it erode? How does it deposit? –Pulls rocks down slopes –Materials pile up at lower elevations

134. Erosion and Deposition Glaciers How does it erode? How does it deposit? –Moving mass of ice –Picks up and drags rock- grinds across other rocks –Digs into land, widens valleys –Rocks dump when glacier melts –Makes moraines and drumlins

135. Erosion and Deposition Running Water How does it erode? How does it deposit? –Drags rocks along in water –Bumping of rocks widens and deepens waterways –FASTER= carries more –Where water slows down, rocks are dumped off –Form deltas/fans or plains

136. Erosion and Deposition Waves How does it erode? How does it deposit? –Crashing waves chip away at rocks –Abrasion forms cliffs, arches and caves –Carried particles are dumped on shore –Form beaches, sand bars, spits

137. Soil forms from the weathering of the rock below it. The solid rock below is called Bedrock. The rock is exposed to wind, rain etc… The rock breaks down over time to form soil. Soil has different layers called Soil Horizons. O- Horizon = the very thin surface covering (not really a layer) A – Horizon (TOPSOIL) = dark surface soil that contains a lot of living material and dead plant/animal remains (humus). This is the layer with all of the nutrients needed to grow plants. B-Horizon (SUBSOIL) = lighter colored soil with less nutrients and more clay C-Horizon (REGOLITH) = larger rock fragments that sit on top of the unweathered bedrock Soils

138. There are 2 types of soil: 1.Transported 2.Residual Transported soils are the most common throughout New York State!!!!!!!! Transported Soils – soils that formed in one place and were transported to their present location by glaciers. You can tell when the soil does not chemically match the bedrock below it. Residual Soils – soils that are located above the rocks that they formed from. In other words, the soil chemically matches the bedrock below it, because it is a product of that rock’s weathering over time. Soils

139. Soil Conservation: Depletion occurs when too many nutrients are removed from the soil for a crop to grow. Crop Rotation is a type of farming used to prevent depletion, crops must be alternated on the same soil each year. Contour Plowing - crops are planted in rows parallel to the contours of the land. Strip Cropping - involves planting strips of low cover crops between strips of other crops.

140. Soil Conservation: Sometimes topsoil is carried down the slopes of a hill by water. To prevent this the land can be terraced or wind breaks can be set up. Terraced – the hill is terraced into a series of level steps.

141. Soil Conservation: Wind Breaks (belts of trees along the edge of farming areas) are set up to prevent the winds from carrying topsoil away. If overgrazing occurs, the land can dry out and the area become a desert. This process is known as desertification.