EARTH SCIENCE NAME_____________________________
A group of contour lines is a device used to express three dimensional surfaces on a flat sheet of paper. A
contour line represents an imaginary line on the ground, every part of which is at the same elevation above sea
level. Wherever you find the 520-foot contour line, for example, the elevation at every point along that line is
520 feet above sea level. The contour interval, always given on topographic maps, is the vertical distance
between any two contour lines.
Figure 5. Diagrams of three types of surfaces with a topographic map for each diagram.
a. Flat surface at 333 feet. Topographic map has no contour lines.
b. Uniform slope from 333 to 363 feet. Topographic map has three uniformly spaced contour lines
at 340, 350 and 360 feet.
c. Two surfaces, one at 333 feet, the other at 363 feet, separated by a very steep slope (cliff). The
topographic map shows three closely, spaced lines which indicate the cliff with blank areas for
the flat surfaces.
Part I. Answer the following questions from the map above.
Which direction (upstream, downstream) do the contour lines point? ________________________
What is the contour interval? feet .
On which side of the map (west, east) are the contour lines closest together?
What generalization can you make about the closeness of the contour lines and the steepness of the slope?
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Part II: On the following page is a contour map with three contour lines and elevations at various
points over the map. Draw in the remaining contour lines using the given ones as a guide
to their shape. The contour internal is given on the map. When you have completed the
map answer the following questions.
1. What is the elevation of line 1? ______________________
Line 2? ______________________
Line 3? ______________________
Going from point A to point D you travel (up, down) _______________________ How many feet?
How many streams must you cross going from point A to C? _____________________________________
What is the major physical feature on this map?
What is the general drainage pattern on this map?
What is the elevation of point C?
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Part III: On the following page is a map with the elevation given at selected points. Draw in the
contour lines starting with 960 feet. Use a contour interval of 20 feet. After the map is
completed answer the following questions.
1. What physical feature is represented?
What is the highest elevation?
What is the lowest elevation?
Where is the steepest incline?
How do you know this is the steepest incline?
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The above represent elevations above sea level. Contour this area, using a contour interval of 20 feet.
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