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Mapping

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What is a map?

  • It is a representation of something (Earth, stars, solar system, a building, etc…

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Uses of Maps

  • To determine where you are going.
  • To act as a model of Earth’s surface.
  • Used to locate various places
  • To show the distribution of various features or types of materials.

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Quick Review of Latitude and Longitude

  • Latitude
    • Measured in degrees North and South of the Equator.
    • Lines drawn parallel to each other running west to east.

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Quick Review of Latitude and Longitude

  • Longitude
    • Measured in degrees East or West of the prime meridian.
    • Lines drawn running North and South.

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Topography

  • The lay of the land.
  • Shows relief using contour lines.
    • Relief- highs and lows of Earth’s surface.
    • Relief can be calculated
      • Take the difference between the highest point and the lowest.
      • Ex: Mountain peak 20 m. lake 10m
        • 20m- 10m= 10m
        • The relief of this area is 10m

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Reading a topographic map- Streams

  • The direction a streams is flowing is shown on a topographic map by the way a contour line crosses the stream.
  • Streams are shown as a blue line on maps.
  • When contour lines cross a stream it looks like an upside down V.
  • The point in the V points

upstream. It opens in the direction the water is flowing.

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Reading a topographic map- Slope

  • Closely spaced contour lines represent steep slopes.
  • Widely spaced contour lines represent gentle slopes.

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Reading a topographic map- Benchmarks

  • A benchmark is a place where exact elevation is known.
    • Shown by a B.M. on map
    • Ex: BM 60

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Reading a topographic map- Colors

  • The colors on a topographic map are symbolic of different map features.
    • Blue = water
    • Green = forest
    • Brown = contour lines
    • Black = cultural features (buildings, place names, boundary lines, roads, etc.)
    • Red = principal roads
    • Pink = urban areas
    • Purple = revisions to an older map, compiled from aerial photos. If an area has become urbanized, this may be shown as purple shading on the new, revised map.

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Reading a topographic map- Map Scale

  • Map scale indicates your distance along the ground, or the amount of ground covered by the map.
  • USGS- United States Geologic Survey
    • Ratio- 1:24000
    • one unit on the map is equal to 24,000 units of the same size on the ground.
      • Ex:1 inch on the map = 24000 inches on Earth.
        • Or after converting 1 inch = 2000ft.
  • Bar scale-indicated by a line or bar with distances marked in miles, feet, or kilometers.

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Reading a topographic map- Map Scale