How Do You Draw Contour Lines On A Topographic Map?
A topographic map shows the elevation of the earth’s surface using lines that connect all of the places that are the same elevation. Such lines are called contour lines. To draw them by hand, you start with a series of points of known elevation that someone has measured and then infer where the lines would be between each pair of points. This process is called interpolation. Draw a triangle that connects three of the points of known elevation. The points should be near each other but not of the same elevation. Choose a contour interval (the spacing between lines) that is such that each side of the triangle crosses between one and three lines. You don’t want it to be too large of an interval or else the map won’t show enough detail, but you don’t want it to be too small or it’ll be cluttered. Once done, erase the triangle. Measure the distance between two of the points. We’ll call them A and B, where A has a lower elevation than B. Draw a right triangle on a separate piece of paper in w
