Lab 8: Mapping - Landforms on Contour Maps - Smooth Slopes


Take a look at any landscape and you see areas of smooth slopes commonly, at least in local patches. The following data has z values that range gradually from the upper left area of the map, down toward the lower right. Scan your eyes across the z values posted at the points to see how the numbers vary:



For each of these examples, you can save it to your computer for printing. You can do that for the maps that have only z values posted, and try your hand at contouring. Each one of the examples has the solution, but it is still a good way to learn to draw the contours by hand, and then compare to the solution, even if you have to keep looking at the solution as you go. Each of the examples uses a contour interval of 50 units (feet, meters, whatever are the units; doesn't matter for learning how to contour, as the z values are just numbers -- but if it helps you can think of the z values in the examples as representing feet, the most common z unit for topographic maps in the United States).


Contours on slopes will run across the slope in roughly parallel lines, perhaps with gentle bending if the slope isn't perfectly. Rarely is a natural slope perfectly planar. On this slope the terrain is even -- there aren't large creeks crossing it, and no large ridges, valleys, or other features. This is shown by generally parallel contour lines:



Contours on slopes run parallel to one another and are usually fairly straight, at least locally.