Concept 2: Contour maps and topographic maps

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Concept 2 Contour maps and topographic maps

• Read dont write this part..
• Big Idea From NYS Standards for Earth Science
• Key Idea 2
• Many of the phenomena that we observe on Earth
  involve interactions among components of air,
  water, and land.
• 2.1q Topographic maps represent landforms through
  the use of contour lines that are isolines
  connecting points of equal elevation. Gradients
  and profiles can be determined from changes in
  elevation over a given distance.

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Field Maps

• 1. Field maps are localized maps that show one
  aspect of the area using isolines and symbols.
• (In Earth Science, field maps are used to show
  elevation, weather variables, pollutants,
  earthquake intensity, etc.)

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2. Map keys and symbols

• a. A map scale is used to measure distance on
  the map.
• b.     A map legend or key identifies the meaning
  of symbols on a map.
• c.    Relief indicates the change on the map from
  greatest to least field value.

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3. Contour Maps field maps that show elevation.

• a.     Contour maps use contour lines (isolines)
  to indicate landscape changes.
• b.     The contour interval between the isolines
  must always be constant, and is usually measured
  in feet or meters.
• c.     Contour lines spaced far apart indicate
  flat land. Those close together indicate steep
  ground.

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continued

• d.     Closed loops indicate hills. Long closed
  loops indicate ridges.
• e.     The maximum possible elevation inside a
  closed loop is one less than whatever another
  contour line would be.
• f.        Depressions (or basins) are shown using
  hachure lines. The first hachure line has the
  same value as the last contour line.

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• g.     The direction a river flows can be
  interpreted two ways on a contour map
•     i.      The contour lines make a v shape
  that points uphill.
•   ii.      elevation indicates which way is
  downhill
• h.      Sea level always has an elevation of 0.
  Elevations below sea level are indicated by
  negative numbers. http//www.visualentities.com/co
  ntour.htm

http//www.sir-ray.com/Topographic20Map20Lab.htm

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4. Finding gradient see p. 1ESRT

• a.     On a contour map, the gradient indicates
  the change in elevation (y value) over the
  distance (x value).
• b.     Units are very important in gradient
  problems.
• For contour maps, the gradient units will usually
  be meters/kilometers (m/km) or feet/miles (ft/mi)

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5. profile maps use the contour lines of a flat
map to show a side view of a cross-section

• a.     The steps to making a profile require
  visuals and practice
• http//user.gs.rmit.edu.au/caa/topo/contours.htm
• http//rst.gsfc.nasa.gov/Sect11/Sect11_2.html
• Vertical exaggeration refers to how much the
  elevation has been exaggerated on the y axis to
  make the change visible over horizontal distance

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• 6. Topographic Maps contour maps that use a
  coordinate system, map scale and key and symbols
  to indicate landforms and manmade structures.

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• a.     Technology has greatly improved
  topographic maps.
• b.     In the United States, the United States
  Geologic Survey (USGS) has made USGS Quadrant
  maps of the entire country.
• c.     The USGS Quadrant maps use coordinate
  systems, including latitude and longitude, to
  indicate the map location in the world.
• d.     Symbols used on these maps are
  standardized to show vegetation, types of
  structures, roads, etc.
• e.     Topographic maps are used for planning and
  to track problems and changes.