Topographic Maps Notes

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Lab questions: Activity 9.1, pg. 219, 9.2, pg. 222.

 

Coordinate systems (where am I?):

Latitude: the lines that run ______ and _______ across a map.

  • Latitude numbers run from zero (the equator) to _____ (the poles).
  • The addition of a N (North) or S (South) indicates which hemisphere you are in.

Longitude: the lines that run ______ and _______ across a map.

  • Longitude numbers run from zero (the Prime Meridian) to ______ (the International Date Line).
  • The addition of an E to the numbers indicates you are in the Eastern Hemisphere and a W means you are West of the Prime Meridian.
  • One degree can be divided into _____ minutes. One minute is _____ seconds.

Quadrangle: The standard size USGS (US Geologic Survey) Map.

  • Covers a square area of 7.5 minutes in latitude by 7.5 minutes in longitude.
  • Why aren't our maps in this area __________?

PLS- Public Land Survey or Township and Range System: This outdated system is still used in parts of the West.

  • Its based on ___ ______ wide sections of Townships (numbers that run off the latitudinal baseline) and Ranges (numbers that are measured from the principal meridian).
  • These 6 miles square blocks can get subdivided into ______ one mile square sections- then quarters, then quarters again.

 

Reading Topo Maps (which way do I go?):

Contour Lines: Lines that connect points of _______ elevation

Sea Level: the ____________ contour line.

Index Contour: The _________ contour lines on a map

Contour Interval: How much the elevation jumps between two ___________ contour lines

Hills: are located in the the center of a bull’s eye of __________

Depressions: where the ground slopes downward. Indicated by __________ marks (whiskers) on the contour lines.

  • The lowest point in a depression is half way inbetween the contour and the _________ contour line down if it had been there.

Magnetic Declination- the difference between true north and where the _________ points!

Stream flow directions: the stream flows ______________ the point in the “V” of the contour that crosses over it.

 

Map Reading Challenges:

Topographic Profile: a _______ section of a map that shows the elevation and slope along a given line.

Vertical Exaggeration: The number of times the _________ scale is greater than the _________ scale. Found by dividing the horizontal fraction scale per _______ by the vertical exaggeration scale per _______.

    • To calculate find out how many inches on the ground is equivalent to one inch on the map.
      • ex. 1:11,520 would be ___________
    • Divide this number by how many inches are indicated in a one inch rise on your vertical profile scale. Use a ruler.
      • ex. If you made a scale whereby one inch equals 120 feet- then the equivalent number of inches in real life would be 120 x ________ = 1440 inches.
    • In the above example the vertical exaggeration would be 11,520 divided by _________ or 8 x.

Gradient (Slope) is calculated by dividing the difference in elevation between to points by its _____________.

Regional (Total) Relief: The difference between the highest and the __________ points on a map (or the fact that you are done with notes!).

 

Map Scales (are we there yet?):

Fractional: a fraction that indicates how the comparative ratio between one unit on the _____ (say an inch) is equivalent to how many of the same units (inches) in real life on the _________.

  • ex. 1a. 1/63,360 or 1:63,360 means one inch on the map is really ___________ inches on the ground.
    • b. How many feet apart are 2 spots that are 4 inches apart on the same map as above? _______

Graphic: because you really don’t know instinctually how far 63,360 inches really is - a _________ bar scale is provided for you.

  • Note: begin measuring distances from ____________!!!

Verbal: indicating the number of inches (on the map) in ______ mile (on the ground).

  • To convert inches to miles divide the total inches by _________ to get the number of feet per mile, then divide by _____ to get the number of inches in a mile.

 

 
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