Activity 3: Contour Profiles and Vertical Exaggeration
   
Although a contour map shows how a variable changes with spatial position, it is sometimes difficult to visualize the change in the vertical dimension. To depict changes in the magnitude of a variable along a particular direction in the map area, it is useful to make a plot of that variable on the vertical axis versus position on the horizontal axis (Fig. 1).Contour profiles or cross sections are planes oriented perpendicular to a map that show how the variable changes in the direction perpendicular to the plane of the map. They can be used to show the vertical character of the Earth's surface (topographic profiles), the top of the water table (water table profile), the depth of the ocean floor (bathymetry profile), or any other contoured variable. By plotting the contoured quantity on the vertical axis versus the horizontal distance, profiles show the difference in the variable along the profile and how fast that parameter changes with horizontal distance.
 

Fig. 1: Topographic profile showing the elevation of the Earth's surface.

  
Contour profiles can be drawn following a simple set of rules. To illustrate the nature of the surface cut by the profile, it is sometimes necessary to construct a profile with different horizontal and vertical scales. This produces vertical exaggeration of the surface trace and should be indicated on the diagram.
 
To complete Activity 3, select one of the following files:word.gif (252 bytes)
 

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