Topographic Maps
A topographic map is a two-dimensional representation (in the
horizontal plane) of a three-dimensional land surface.
Scale
Cartographers (map-makers) produce maps to be certain sizes relative
to the geographic area they represent in order to make them easier for
us to use. The ratio of a distance on the map relative to that distance
in reality is the map scale, and is shown as a fraction or ratio. For
example:
1:24,000 or 1/24,000
is a common map scale in the US, where any one unit of measurement
on your map (inch, centimeter, etc.) is equal to 24,000 of those units
in the real area. So, for an inch measured on your map:
1” = 24,000” = 2000’
So, one inch equals 2000 feet on a map that is 1:24,000 scale.
Elevation Representation
A topographic map shows elevation information by using contour
lines, lines that connect points of equal elevation, to represent vertical
elevations of hills and valleys. Elevation is measured relative to mean
sea level.
Contour interval is the difference in elevation between contour lines.
If the land surface or region is gentle and smooth (e.g. New Orleans
area), then contour lines are widely spaced because elevation
changes very little over long distances.
If the land surface or region has more “topographic relief” (e.g. mountains or hills) then contour lines are closely spaced because
there are greater differences in elevation over small.
Compass Direction
Compass Direction
Azimuth
Bearing is the compass direction along a line from one location to
another.
Bearing can be given in a number of ways, including quadrant in
degrees east or west of north or south, or as an azimuth which
varies from 0° to 360°.
A trick about using a compass…
*Because of the characteristics of the earth’s interior and plate tectonics, and the magnetic poles move (wander) over time. This
means that a compass measurement of magnetic north must be
corrected to get a measurement of geographic north.
Magnetic declination is the horizontal angle between the direction of
geographic north (true north) and magnetic north, and is different
depending on where you are on the earth. The declination in a
particular area is always noted somewhere on a topographic map.
Coordinate Systems)
A coordinate system is like an x-y graph – if you want to locate
something on a map, you use the two coordinate lines (x and y), and
where they meet is your location.
Latitude: imaginary lines that run from west to east (horizontal in
map view).
For latitude, 0 is the equator, and latitudes are designated north or
south of the equator. The latitude measurement increases to 90 at
both the north and south poles.
Longitude: imaginary lines that run from north to south (vertical in
map view).
For longitude, 0 is a vertical line (called the prime meridian) passing
through the town of Greenwich, England and the north and south
poles. A longitude measurement is designated either east or west of
the prime meridian, up to 180
A degree of latitude or longitude can be subdivided:
One degree = 60 minutes (60’) = 3600 seconds (3600”)
Universal Transverse Mercator (UTM) (see p. 155/ 7th ed. P. 181):
UTM is the coordinate system used by global positioning systems
(GPS), the satellite network that allows for accurate location with
hand-held GPS receivers.
In UTM, the globe is divided into 60 north-south zones, each 6° of
longitude wide. Within each zone, the coordinates are given as:
Easting is the number of meters east of the western boundary
of the zone.
Northing is the number of meters north of the equator.
UTM grid lines are often provided on maps to divide it into 1x1
kilometer squares. The grid is marked off to the nearest kilometer
from easting and northing. You have to use a scaled UTM grid or a
ruler to measure distances within the 1x1 kilometer grid to accurately
place your location.
Name _________________________ Section ________________________
Topographic Maps: Contour Line, Map Construction and Use
YOU WON’T BELIEVE THE FUN YOU CAN HAVE WITH MAPS!!!
Part 1: Visualize Topographic Contours!
Each container has 6 (six) dashed lines. Each of these lines represents 100 feet of elevation.
Put your volcano island in the container, and fill the container with water until it reaches the first line.
Place the transparent plexiglass on top of the container and draw the water outline onto the plexiglass using the
marker. This is a line of equal elevation, a contour line.
Fill the container until it reaches the second dashed line, and draw the second contour on the plexiglass with the
marker. Continue this process up to the last dashed line on the container.
Answer the questions below after all contour lines are drawn.
1. What is the contour interval (in feet)? _______________________________
2. What is the highest elevation in feet, approximately? ____________________
3. Describe the area of the island which has the steepest topography. How do the elevation contours represent
this?
_______________________________________________________________________________________
_______________________________________________________________________________________
__________________________________________________________________________
4. Describe the area of the island which has the gentlest topography. How do the elevation contours represent
this?
_______________________________________________________________________________________
_______________________________________________________________________________________
__________________________________________________________________________
Part 2: Indulge in the Mysteries of Topographic Contour Lines!
Part 3: Use a Topographic Map!
Answer the following questions based on the topographic map provided.
1. What is the highest elevation (in feet)? _______________________________
2. Which city is the lowest elevation (Rockville, Norton or Dixon)? Why?
_______________________________________________________________________________________
_______________________________________________________________________________________
_________________________________
3. Which mountain or hill contains the steepest relief on the topographic map (Bear Mountain, White
Mountain, Summit Hill or Bald Peak)? Why?
_______________________________________________________________________________________
_______________________________________________________________________________________
_________________________________
4. Which mountain or hill contains the gentlest relief in the topographic map (Bear Mountain, White
Mountain, Summit Hill or Bald Peak)? Why?
_______________________________________________________________________________________
_______________________________________________________________________________________
_________________________________
5. How far apart (in miles) are Norton and Dixon?______________________________
6. How far apart (in miles) is the highest point on Bear Mountain from the highest point on Summit Hill?
___________________________________________________
7. Which stream (Roaring Stream, Rapid Brook, Fish Creek or Dark River) originates at the highest elevation?
What is that elevation?________________________________
8. What is the longitude and latitude (in degrees, minutes and seconds) of Dixon, Norton, and Rockville?
Dixon:
latitude __________
longitude ___________
Norton:
latitude __________
longitude ___________
Rockville:
latitude __________
longitude ___________
9. Give the compass bearings in azimuth for the following:
Bald Peak looking to White Mountain_________________________________
Bear Mountain looking to Norton_____________________________________
Bald Peak to the mine to the southeast_________________________________
Part 4: Construct a Topographic Profile!
Part 5: Use UTM coordinates and measure compass bearings!
Using the proper UTM grid above, answer the following questions:
1. You are with Al Copeland in his cigarette racing boat out on Garibaldi Lake. Since you
need to radio his helicopter to deliver your Popeye’s Cajun Combo lunch, he uses his
GPS to get the boat’s UTM easting and northing coordinates: 98600 60750. Plot the
boat’s position on the map above.
2. What are the UTM coordinates of the Popeye’s Chicken located in the cabin near the
Battleship Islands?__________________________
3. What are the UTM coordinates of the giant Popeye’s Chicken neon sign that sits atop the
peak of Mount Price?_____________________
4. When you and Al Copeland are sitting eating cheesecake from the Cheesecake Bistro at
the cabin by the Battleship Islands, along what bearing must you look to admire the giant
neon Popeye’s Chicken sign on Mount Price? ____________________________