Reading Maps

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Reading Maps

• Ge133 Fall 2006
• Lab 3

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Map Types

• Road Maps
• Topographic Maps
• Geologic Maps
• Political Maps
• Ski Slope Maps
• Relief Maps
• Hybrid

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Road Maps
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Topographic Maps

• Quadrangles Represents a section of the Earths
  surface bounded by lines of latitude and by lines
  of longitude
• Compass Bearings Azimuth or Directional
• Scales Graphic, Representative Fraction , and
  Verbal Scale
• Contour Lines Map elevation changes
• Index Contour Starting point for interpretation
• Contour Interval Elevation difference between
  lines

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Fundamental Definitions

• Topography The general configuration of the
  land surface
• Altitude The elevation of a point with respect
  to an accepted datum (usually mean sea level).
  Altitude numbers are always brown.
• Relief The difference in elevation (altitude)
  between two points.
• Contour Lines Continuous lines drawn through a
  series of points all of which have the same
  elevation.
• Bench Mark Generally abbreviated B.M., is a
  single point of known elevation from which any
  future surveys may begin.

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Interpreting Contours

• All points on one contour line are of the same
  elevation.
• Contour lines never intersect.
• A vertical cliff is represented by coincident
  contours.
• Contour lines point upstream.
• Uniformly space contours represent uniform slope
• Contours spaced far apart indicate a gentle slope
• Contours spaced closely indicate a steep slope

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Coordinate Systems

• Latitude and Longitude
• Latitude Angular distance of a point on the
  Earths surface north or south of the equator,
  the equator being 0 and the north and south
  poles at 90
• Longitude Angular distance of a meridian of a
  given place and the prime meridian, has a max of
  180 from the prime meridian.
• UTM (Universal Transverse Mercator)
• The projection used on so many world maps is a
  cylindrical projection, meaning the globe is
  encircled by an imaginary cylinder touching at
  the equator, and the earth is projected onto the
  cylinder