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What is topographic or contour map

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What is topographic or contour map Powered By Docstoc
					  What is a
topographic
(or contour)
     map?
A topographic map shows elevation –
or how high or low a land feature is.
      It shows features such as –
    Mountains

    Hills

    Lakes

    Depressions  or valleys
    By using lines on a flat map.
  A topographic
      map is
sometimes called
 a contour map.
Here are some examples
of topographic maps.
 You can understand
  how high or low a
geographic feature is
  on a contour map
because of its use of
   numbered lines.
 The lines are called CONTOUR LINES.
 They are a certain distance apart.

 The number of meters or feet in
  between each contour line is called the
  CONTOUR INTERVAL.
 For example – if a hill is shown as 10
  feet, 20 feet, and thirty feet – the
  CONTOUR INTERVAL is 10 feet
  because that is the difference between
  each contour line.
Not all contours lines go up!
 Sometimes, a land feature like a valley
  or depression is found on a map.
 Instead of a regular contour line, the
  feature will instead have a contour line
  with little “hatchure” marks going down.
  These marks look like little slashes.
 This tells us that instead of going up in
  elevation, that particular land feature is
  going down.
On the next slide, you’ll see a
contour map of excavations at the
old Twin Towers site in New York
City. Construction crews uncovered
glacial formations 20,000 years old
once they removed the soil. Instead
of using hatchure marks, the
cartographers used negative
numbers to show that all landforms
went into the ground rather than
above it.
A topographic map can
 also show you what
  the land is like. For
 example, a swampy
  area will be shown
 with little sprigs that
    look like plants.
    How can you quickly find
    steep hills and mountains?
 Just look for the shaded areas on the
  map.
 The steeper a feature is, the closer
  together the contour lines will be.
 In other words, the steepest areas
  on a map are the ones that look the
  darkest.
 Here is an example…
You will be starting a
 map lab and will be
answering questions
about features found
  on contour maps.
Remember what you
 just learned and you
will be able to “see” a
 land feature in three
   dimensions, even
though the map itself
         is flat!
THE END

				
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