• Symbols are representative signs that simplify the details of a map.  It is absolutely important to learn the symbols used on US topographic maps.  You will be expected to know these!  I have created a Quizlet for you to study and quiz yourself.  Please bookmark the following link and start studying!  If you do 5 or so every night, you'll pick it up in no time.  Most of the symbols make perfect sense, making it easier to learn!  QUIZLET: https://bit.ly/3gJ35SY

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• Note that on maps, symbols are not always drawn to scale and are sometimes exaggerated.

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• Map symbols can be different colors

  • Blue= water,

  • Green= vegetation, forested

  • Black= man-made objects and roads,

  • Red= grid boundaries and major roads,

  • Red/Gray = densely built up areas

  • Brown= contours

  • Purple= revisions made using aerial photography

 

Start studying the Quizlet app ASAP. Become familiar with all of the symbols!

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• Contour Lines are brown lines on topographic maps showing constant height above sea level. This is a kind of altitude. You can determine the general shape of the land by seeing how contour lines are drawn.  If you walked along a contour line, you would be walking a perfectly level path; neither uphill or downhill.

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• Contour lines depict places of identical elevation.  Elevation is simply the height above something, in this case, the height above  Sea Level .  So Sea Level is always a height of 0 (zero).

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• Contour lines are what allows the topographic map to show three dimensions and differentiates topographic maps from planimetric maps.  It is very helpful to be able to interpret topographic contour lines so you can visualize the geography it represents.  This comes with practice.  Some geographic features and the way they are shown with contour lines are presented below.  Try to see the geography in your mind when looking at topo maps.

  • Look at contour lines in large scale.  They paint a picture of the terrain.  Don't focus on just one contour line, look at the surrounding area and see the landscape in your mind.

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• Contour lines ultimately always form complete loops even if they must extend onto other adjacent maps.

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• Mean Sea Level (MSL) is the average height of the oceans around the world.  Due to the rotation of the Earth and gravitational effects, the sea is not actually level.  So a reference location in Canada is used to define mean sea level.  More on this later.

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• A device that reports your altitude is called an altimeter and is basically a barometer that is calibrated to show height above the ground or seal level.  (Fun fact; normally barometric pressure drops approximately 1" of mercury for every 1,000 feet you climb in elevation.)

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• Index Lines are contour lines that are bold and labeled with a number indicating the height in feet above seal level. Every fifth contour line is an index line.

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• Intermediate Lines are contour lines between Index Contour lines.

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• A Fall Line is perpendicular to contour lines.

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• A Contour Interval is the height difference between two adjacent contour lines. The actual contour interval is always denoted on the bottom of a topographic map by the scale, but is usually 20 feet.

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• Depressions, such as a pit, are depicted with hatch marks (hachures) on the contour lines. The first hatchured line has the same elevation as the one next to it, but outside the hachured line.  The hatchures point toward lower ground.

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Some typical contour line configurations:

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The easiest formations to see are hills.  They are formed by closed circles as shown here.  When a hill is fairly small, it's called a knoll.

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