3-D Topographic Maps

piloted for the NYC and NYC Watersheds Trout in the Classroom program
by Tina Miner-James, TIC Teacher
designed by the Catskill Center for Conservation and Development

Objective:
    To teach students that a topographic map represents three-dimensional space and to find their place on the landscape.  

Background: 
    The forested landscape of the Catskill Mountain region provides wonderful habitat for trout and an ideal source for New York City's drinking water supply.  The gentle flowing water from the Catskill Mountains provide oxygen and removes pollutants that can harm trout.  Understanding the landscape can better help students understand the geology of the watersheds the placement of dams and reservoirs that provide New York City with cool, clean water primarily through gravity.

    Topographic maps are a critical tool for understanding any terrain.  Isolines on a topographic map delineate places of equal elevation.  The spacing and shape of the isolines can also tell us characteristics of the land.  For example, closely spaced isolines show a steep slope, whereas broadly space lines indicate a flatter terrain.  This can be hard to see on a flat piece of paper, especially for students who have little experience reading topographic maps.  The following exercise “pops” the hills and mountains out of a topographic map, and can help students see the landscape better when they return to reading two-dimensional maps.
 
Materials:
multiple copies of an 8.5 x 11 inch area of a USGS topographic map of the trout stream area or watershed (one copy per 100 feet of elevation on the map, plus spares, preferably in color), markers, scissors, glue sticks, flattened cardboard boxes

Procedure:

  1. Break the class into teams.  Each team can have the same piece of one map, or have different areas.  If each team takes a piece of a contiguous area, the resulting pieces can be put together to form a larger landscape.  Give each team all the copies they’ll need to complete the project.
  2. Have each team find their lowest and highest elevation isolines, to the nearest hundred.  Then have each team designate (label) their copies for each hundred feet present in their map, plus a base.  (For example, if a team’s lowest elevation is 800 feet, and their highest is 1800, they will need 12 copies of their 8.5 x 11 map section.  The first will be labeled base, then 800, 900, 1000, and so on to 1800.)
  3. Leaving the base aside for the moment, have students trace their designated isolines with a marker on each map.  For example, on the map labeled 800, the student will trace all lines that are at an elevation of 800 feet.  On the 900 map, all the 900 foot isolines should be traced.
  4. Students should now cut along the traced lines, saving the piece of paper with every elevation above the designated line.  The below sections can be set aside (and eventually recycled).
  5. Have students glue the base and all the saved pieces (the number and all the elevation above it) to cardboard with a glue stick.  Now have them cut it out.  This cardboard represents 100 feet of elevation.
  6. Starting with the base, students should carefully stack, align, and glue the pieces on top of one another.  When gluing the 800 piece on the base, for example, they should look for the 800 isoline on the base map, and carefully align their 800 (and up) piece with that line.

Wrap-up:
    Ask students to compare their three-dimensional maps to the two-dimensional original.  Now ask them what different isoline patterns mean, such as closely space lines, or lines in a tent or V shape, by looking at their models.  Students can also fit their individual 8.5 x 11 inch sections together to create a watershed or landscape.  Have students locate your school, trout release stream, or field trip site.

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