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Erosion
 

Erosion

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    Erosion Erosion Presentation Transcript

    • Erosion
    •  
    • A. Definition (pp. 264-265)
      • Erosion is the carrying away of weathered particles (rocks, soil, sediment).
    • B. Agents of Erosion
      • Water
      • Gravity
      • Wind
      • Glaciers
    • C. Water
      • Water cycle – the process by which water circulates between the earth and the atmosphere
        • Evaporation
        • Condensation
        • Precipitation
        • Collecting as groundwater or runoff
      Click for animation
    • Does evaporated water only come from oceans?
    • C. Water
      • Surface water vs. groundwater
      • Moving water is the most constant agent of erosion.
    • D. Rivers (pp. 265-272)
      • River system
      • runoff  stream  river  ocean
      • *runoff – surface water that drains into a stream
      • *drainage basin – all the land drained by a river system
    •  
    • D. Rivers
      • Factors affecting erosion by rivers
        • Climate – rainy vs. dry
        • Heavy rainfall
        • Plants
        • Soil type – clay vs. sand
        • Type of bedrock – sandstone vs. shale
    • D. Rivers
      • River erosion happens as water carries dissolved minerals, suspended particles and rocks (load).
      Click for animation
    • D. Rivers
      • Erosion produces the river valley by:
        • Slope retreat – valley becomes wider
        • Headward erosion – valley becomes longer
    • D. Rivers
      • River valley stages
        • Young – valley is V-shaped, narrow and fast; with rapids and waterfalls
        • Mature – valley is wider than the channel; floodplains develop
        • Old – valley is much wider; meanders develop; oxbow lakes may form
      Click for animation Click for animation Click for animation
    • Identify the stages and describe the associated features.
    • Identify the stages and features.
    • D. Rivers
      • Factors of a stream’s load size
        • Size of the particles
        • Weight of the particles
        • Speed of the water current
      Click for animation
    • D. Rivers
      • Where load deposition occurs
        • Where the water slows down as the channel curves
        • On floodplains
        • At the base of a mountain in dry climates (alluvial fan)
        • At the mouth of the river (delta)
      Click for animation Click for animation Click for animation
    • Alluvial fan Delta
    • Let’s Review!
      • The changing of water vapor in the air into water droplets in a cloud is called ______.
      • A. Condensation
      • B. Evaporation
      • C. Precipitation
      • The most constant agent of erosion is ____.
      • A. Glaciers
      • B. Wind
      • C. Water
      • If there are many trees in a drainage basin, there will be ____ erosion by rivers.
      • A. less
      • B. more
      • C. no effect on
      • The river shown in the picture is ___
      • A. young
      • B. old
      • C. extinct
      • What may cause the situation shown here?
    • Groundwater The Musical
    •  
    • E. Groundwater (pp. 274-277)
      • Erosion occurs as groundwater slowly moves through the earth, leaching minerals from soil and dissolving rocks away.
      • Groundwater is usually hard water which means it contains dissolved minerals (vs. soft water with no or few dissolved minerals).
    • E. Groundwater
      • Groundwater can pass through porous (permeable) rocks and cannot pass through impermeable rocks.
    • E. Groundwater
    • E. Groundwater
    • E. Groundwater
      • Groundwater can come up to the surface in:
          • Springs
          • Hot springs
          • Geysers
          • Wells (manmade)
      Click for animation
    • Which illustration shows a problem?
    • E. Groundwater
      • Limestone caves are produced by groundwater erosion. Stalagmites, stalactites, pillars and curtains are produced by deposition.
      Click for animation
    • E. Groundwater
      • Long-term groundwater erosion may produce sinkholes and solution valleys.
      Click for animation
    • Sinkholes
    • Karst towers and solution valleys
    • Let’s review! Click for animation
    • F. Waves (pp.279-281)
      • Surface waves are produced by wind.
      • Erosion occurs as abraded particles are washed away as the waves attack and retreat.
      Click for animation Click for animation
    • F. Waves
      • Shoreline features formed by wave erosion
          • Sea cliffs
          • Sea caves
          • Sea arches
          • Sea stacks
      Click for animation
    •  
    •  
    • F. Waves
      • Shoreline features formed by wave deposition
          • Beaches
          • Sandbars
          • Spits
          • Barrier islands
    •  
    •  
    • G. Gravity (pp. 288-289)
      • Mass movement is the downslope movement of rocks and soil due to gravity.
      • Types of mass movement
          • Falls – rockfall
          • Slides – rockslide, landslide, slump
          • Flows – mudflow, avalanche, creep
      Click for animation
    • G. Gravity
      • Factors that trigger mass movement
          • Saturation of surface materials with water
          • Oversteepening of slopes
          • Removal of trees and vegetation
          • Earthquakes
    • Falls
    • Slides
    • Flows
    • 200 Feared Dead in Philippine Landslide
      • From the Guardian Unlimited (Feb. 17, 2006)
      • More than 200 people were feared dead today after a huge landslide buried hundreds of houses and a school full of pupils in the eastern Philippines.
      • Another 1,500 people were missing after mud slid down a mountain on Leyte island, Red Cross officials estimated.
      • "It sounded like the mountain exploded, and the whole thing crumbled," Dario Libatan, a survivor, told Manila radio DZMM. "I could not see any house standing any more."
      Survivor rescued
      • The governor of southern Leyte province, Rosette Lerias, said 500 houses in Guinsaugon village were feared buried after two weeks of solid rain. A primary school was open when the landslide struck, at around 9am.
      • "There are no signs of life: no rooftops, no nothing. The ground has really been soaked because of the rain," Ms Lerias said of the downpours, which have been blamed on the weather phenomenon known as La Niña. "The trees were sliding down upright with the mud.“
      • Villagers have said the slide was caused by excessive heavy rain and illegal logging, which removed the ground cover.
      • US marines join other rescuers
      The mud was up to 10 metres deep in some places and so unstable that rescue workers had difficulty approaching the school. Education officials said 250 students and teachers were believed to have been inside the building.
      • A local dignitary, Eva Tomol, said only three houses remained standing in the village, which is 420 miles south-east of Manila. Six survivors were being treated at a hospital, she said.
      A man grieves the loss of his family
      • Richard Gordon, head of the Philippine Red Cross, said the entire village appeared to have been buried in unstable mud. He appealed for US troops, currently in the country for a series of joint military exercises, to send heavy-lift helicopters to the landslide scene. A C-130 Philippine military transport plane was to fly to Leyte later today carrying search equipment and a team of sniffer dogs.
      • Anthony Golez, deputy administrator of the office of civil defence, said two rescue helicopters and two navy ships had been sent to the remote area, where about 200 rescue workers, volunteers from nearby provinces among them, were trying to dig out survivors.
      • "We want to get a clearer picture of what happened and then also mobilise the army there," Mr Golez said.
      • "Let us all pray for those who perished and were affected by this tragedy," the president, Gloria Arroyo, said. "Help is on the way."
      • In November 1991, about 6,000 people were killed on Leyte in floods and landslides triggered by a tropical storm. Last weekend, seven road construction workers died in a landslide after falling into a ravine 46 metres deep in the mountain town of Sogod on the island.
      • Click for video
    • Points for Discussion
      • What caused the landslide?
      • What factors could have contributed to it?
      • Could it have been prevented? How?
      • Who should take responsibility for such tragedies?
      • What can we do about it?
    • H. Wind (pp. 290-292)
      • Factors of wind erosion
        • Wind speed
        • Particle size
      • Wind deposits
        • Loess – thick deposits of silt and clay
        • Sand dunes – hills of sand moved by wind
      Click for animation Click for animation Click for animation
    • H. Wind Windward side Leeward side
    • Sandstorm
    •  
    • I. Glaciers (pp. 294-300)
      • Glaciers are huge moving bodies of ice forming where snow accumulates through the years.
      • Factors of glacial movement
        • Gravity
        • Weight of the ice block
        • Uneven thickness of the ice block
      Click for animation Click for animation
    • I. Glaciers
      • Glacial erosion occurs as rocks and weathered particles are frozen onto the glacier (glacial plucking) and are then carried along.
    • I. Glaciers
      • A glacier deposits its load where it melts; producing a pile of unsorted sediment (till) in ridges (moraines).
    • I. Glaciers
      • Types of glaciers
        • Valley glaciers
          • Develop in mountain valleys
          • With large cracks (crevasses)
          • Features produced by erosion
              • Cirque
              • Horn
              • U-shaped valleys
              • Fjord
      Click for animation
    • Valley Glacier Cirque
    • Valley Glacier Horn
    • Valley Glacier U-shaped Valley
    • Valley Glacier Fjord
    • I. Glaciers
      • Features produced by deposition
          • Lateral
          • moraines
          • Medial
          • moraines
          • Terminal
          • moraines
    • Valley Glacier Moraines
    • I. Glaciers
        • Continental glaciers
          • Large sheets of ice covering large areas of land
          • At the edge, where it meets the sea, pieces of the glacier may break and float off (icebergs).
      Click for animation Click for animation
    • Continental Glacier
    • Continental Glacier Icebergs
    • I. Glaciers
          • Features produced as the ice melts
              • Ground moraines
              • Outwash
              • Esker
              • Drumlins
              • Kettles and kettle lakes
      piles of sorted sediments
    • Continental Glacier Moraines
    • Continental Glacier Ground moraines
    • Continental Glacier Outwash
    • Continental Glacier Eskers
    • Continental Glacier Drumlins
    • Continental Glacier Kettle and kettle lake
    • Continental Glacier Kettle lakes
    • Let’s Review! Click for animation
      • What type of glacier is this? 
      • Is the ridge at location A composed of bedrock or sediment?
      A B
      • Name the specific landforms at locations A and B.
      A B
      • Is the sediment in the image glacial till or glacial outwash?   How can you tell?
      • What is the process by which a glacier carries off rocks from the earth?
      • What are the surface cracks in a glacier called?
      • What glacial landform is the arrow pointing to?
      • What glacial landform is the arrow pointing to?
      • Can you identify this famous mountain?
      • Where is this biggest glacier in the world?
    • What environmental issue do these pictures show? What can we do about it?
    • The End