To learn how to make a topographic map, it's good to start with a concrete example. With a ruler, some modeling clay, a piece of dental floss, a piece of paper and a pencil, you can make a model and then make a topographical map of your model. When you're done, you'll have a map that represents the three-dimensionality of your sculpture, and understand how it works.
Preparing the Model
Take your modeling clay and sculpt an asymmetrical mountain. It can be as large or as small as you like, just be sure it isn't symmetrical. Use a ruler to measure the mountain's height in one-inch segments. Mark each inch with the pencil. Do this on two opposite sides of the mountain.
Push a pencil through the mountain, from the top down through the bottom, in two places.
Use a length of dental floss, held tightly between your hands, to slice the mountain completely through at each one-inch measurement, so you end up with parallel slices of the same thickness.
Making the Map
Take the smallest slice of the mountain and trace around it on a piece of paper. Trace the two holes where you pushed the pencil through as well. You'll use these holes to line up the other slices.
Take the next biggest piece and line up the holes with the circles you made on the paper. Trace around the section. Continue this process with the rest of the slices, until you have traced the biggest slice.
Now make your topographic map key, by writing that each contour line is equal to one inch.
Reading the Map
Look at your topographic map. Can you tell where the steepest part of the mountain appears? Can you easily see the highest part of the mountain? What else can you tell by looking at the map compared to the clay mountain?
Look at a topographic map of a region. Compare the contour lines on that map to the one you made. What is similar? What is different? What other information appears on the topographic map you are studying?
In the field, geologists can't cut a mountain into slices to make topographic maps, but they use the same process. A mountain is first divided into units of measure, such as feet or miles. Sometimes markers will be placed in stone to note these measurements.
At each defined height, a survey is made of the mountain's size and shape. The result is a two-dimensional map exactly like your topographical map, that shows not only height but the width and shape of geological features.
Wondering why is the study of geology important? From mining to fuel research to farming, our lives are improved every day by our study of the Earth.
Learning how to read topographic maps is a simple matter of decoding the symbols and numbers that mapmakers use. Once you know what those numbers and symbols represent, you can unlock the information the map contains.
These simple and fun geology activities will expose kids to the different forces and materials that make up our amazing world.