Map Reading 101

Orienteering maps are specially designed for use in orienteering competitions and contain much more detail than a general-purpose topographic map. These maps are sometimes a bit overwhelming to first-timers, but once you break-down the basics, they’re extremely helpful when out on the course. Below is a sample of a typical orienteering map accompanied with an explanation of each section.

Title Block:  This section of the map will include the name of the map (which is usually also the location where the event is taking place), the scale of the map, and the contour interval.

Legend:  The map legend is a key that explains all the symbols used on a map.  Keep in mind legends are not always printed on maps used during races though; they simply take up too much space. See under Clue Sheet (below) for a handy one-page printable version showing all orienteering map symbols side-by-side with the Clue Sheet symbols.

Map Colors:  As you’ll notice, orienteering maps are quite colorful.  These colors are meant to show the differences in vegetation and their density.

  • White signifies a runnable forest with little or no undergrowth.

  • Green indicates a forested area of low visibility and reduced running speed.  The darker the green, the harder it is to see and run through. (Green stripes indicate reduced running speed due to undergrowth without reduced visibility)

  • Yellow/Orange shows “open” vegetation such as grass or prairie, or ground barren of vegetation (deserts). The density of the color shows how clear the area is:  light colors are for rough open land with taller grass; dark colors are for open land.

  • Blue indicates water features such as lakes, ponds, rivers, streams, and marshes.

  • Black indicates rock features, trails, and man-made objects.

  • Brown indicates land forms, such as earth banks, knolls, and is used for contour lines (see below)

  • Purple is used for course planning (start, finish, checkpoints, water stop) and information on areas and routes that are out-of-bounds.

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Contours (and some land forms): (when viewing on a computer, click the image to enlarge to see detail.)

  • Contour Lines: Thin brown lines on the map, each forming a continuous loop (unless reaching the edge of the intended map area). The space between 2 contour lines indicates a change in elevation of the terrain, usually 5 m on regular, small scale, forest orienteering maps. Contour lines do not intersect.

  • Index Contour Lines: Every 5th contour line is thicker and is called Index Contour Line.

  • Form Lines: Thin dashed brown lines are used to depict extra ground shape detail between 2 contour lines, where only one extra form line can be between 2 contour lines and may extend only for a short stretch. Form lines do not intersect contour lines, either.

  • Slope Line: Small brown "tick marks" may be drawn on the lower side of a contour line to clarify the direction of slope. When used, they should be placed in Re-entrants.

The ability to accurately read contour lines takes years of experience to master, but there are several key contour types which you’ll frequently see on maps.

  • "O" Contours - contour line forming the innermost oval or circle in a set of contour lines. They depict either Hill Tops (H) or Depressions (D). A Depression should have at least one Slope Line (D1) unless the depression has water (D2), thus clarifying its center is downhill.

  • "U" and "V" Contours - contours may show "U" shapes (R1, Sp2, Sp3) or "V" shapes (R2). While "U" shapes may represent a Spur (Sp) equally so as a Re-entrant (R), "V" are usually Re-entrants. The "V" shape of re-entrants comes in handy if there are no other symbols that help quickly identifying what is down-hill (slope lines in re-entrants, water features like marshes or lakes, earth banks or cliffs) 

  • Earth Banks - depict steeper drops in the terrain. An earth bank may follow along a contour line, but may intersect contour lines

    • Impassable Cliff - represents a steep drop of more than 2 m, whether it is truly  a cliff, or just a very steep earth bank.

  • Erosion Gullies - the thick brown line symbol with pointed ends is used for very narrow and deep re-entrants, where the width is smaller than what can be represented with contour lines (8 m) and the sides of the re-entrant are so steep that they would have to be represented by an earth bank. Erosion gullies with a depth of less than 1 m are represented by the "Small Erosion Gully" dotted brown line symbol.

Course/Checkpoints:  The purple or magenta colored circles indicate the checkpoints (CP’s).  These CP’s will also have a number beside them which indicates an identifying number of the CP (matching the number of the electronic time stamp unit that is usually attached).  And in Line-O races, the CP’s will have magenta lines that connect the CP’s [in order].  These are to assist the racer in being able to quickly identify the location of the next CP.  Also note that the CP shaped like a triangle is the start, and the double circle is the race finish (these are often at the same place).  These CP's must be the first and last that are visited and "punched" (term used for recording the visit to the CP, usually by electronic means).

Clue Sheet/Control Descriptions:  The major purpose of the clue sheet is to indicate the micro-location information of the control points. In addition to confirming the location depicted already by the map symbol, e.g., a tree or rock, a corner of a fence, it will further indicate if it’s, e.g.,on the north or south side of it.  For a complete list of these Clue Sheet symbols, you can visit the IOF Control Description Handbook. Or for a handy one-page printable version showing orienteering map and clue sheet symbols side-by-side, check here.

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Out-of-Bounds: Areas on a map that are out-of-bounds may have up to three different ways of being marked: 1) pattern of vertical black lines, one usually shall stay out of the entire area; 2) olive green, usually used in more urban areas, where one can still run on the streets, but not through the adjoining private properties; or 3) purple cross-hatch, usually applied to the map at the same time with control points and courses, usually depicting areas that shall not be entered for that specific event, e.g., due to environmental or other, usually temporary reasons.

North Lines:  “North lines” are the black lines on the map that run from magnetic south to magnetic north.  These series of reference lines allow orienteers to quickly orient their map to magnetic north with the use of their compass.