Weathering, erosion, and topography


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Weathering, erosion, and topography

  1. 1. Weathering, Erosion, and Topography
  2. 2. 1. Weathering and Erosion A. Weathering: exposure to air, water, or ice, causing the rock to break down chemically and mechanically. B. Erosion: the movement of weathered material. C. The "Maltese Cross", a well-known rock formation in the Cedarberg Mountains, Western Cape Province, South Africa. These hard sandstones have been shaped into tall pillars and other fantastic forms by weathering along the vertical cracks in the rock.
  3. 3. 2. Deposition and Compaction A. Deposition: the dumping of sediment in a new location by erosion; often at the mouth of a river or at some solid structure that impedes movement (such as a jetty. B. Compaction: as layer upon layer of sediment builds up, pressure on the lower layers causes sediment to stick together and form solid rock. LAYERS! ALLUVIAL FAN!
  4. 4. 3. Erosion Patterns A. Solid rock and/or land begins to erode. B. Small valleys begin to form. C. Some parts wear away faster than others. D. After thousands, even millions, of years, landforms have altered dramatically.
  5. 5. 4. Coastline Patterns A. Deposition occurs along coastlines, often forming small landmasses called jettys. B. The contour of the coastline often changes with deposition of new sediment and erosion of existing land.
  6. 6. 5. Other Affects on Coastlines A. Coastlines are also affected by weather patterns. B. Air from the coast blows inland, causing cities on the coast to be similar to the water temperature rather than inland counterparts 1. Warm air causes coastal cities to be warmer than the inland while cold air causes the coastal city to be colder than the inland.. C. Large landmasses can create currents that travel up or down coastlines, causing temperature differences. This is especially obvious on smaller landmasses, such as islands.
  7. 7. 6. Topography A. Topography: the surface features of an area. B. This map shows the presence of an island but gives no clue how tall the island is. C. Topographic maps are 2 dimensional representations of 3 dimensional landforms.
  8. 8. 7. Building a Topographic Map A. Always start at Sea Level: 0. B. Select an interval (on this map 10 ft). C. Trace the land contour at each interval.
  9. 9. 7. Building a Topographic Map D. When done, you have a topographic map. E. Now you know how high some features are compared to others.
  10. 10. 8. Reading a Topographic Map A. Contour lines: points of equal elevation. 1. Contour lines cannot cross B. Contour interval: the difference in elevation between 2 lines. C. Index contour: elevation lines that are labeled and usually darker than others. D. What is the contour interval of this map? 1. Hint: pretend it’s a thermometer. 20 ft
  11. 11. 8. Reading a Topographic Map E. What is the interval of this map? F. The closer the lines, the steeper the landform. G. The farther away the lines are, the flatter the landform. H. Label the steepest and flattest parts of this map. 20 ft STEEP STEEP FLAT FLAT