How to Use an Elevation Map

Purchase a topographic map of an area you are familiar with. USGS 7.5-minute maps are very popular and widely used because of the standardized format, relative accuracy and ease of use associated with them. Using an elevation map for the first time can be confusing since there is a substantial amount of information printed on the map. Referencing a map of an area you know well will help you with the learning process. USGS quadrangle maps can be purchased in bookstores, map centers and even online.

Familiarize yourself with the title of your topographic map. Note that the map name ends with the term quadrangle. Quadrangle means rectangular and is typically associated with the standard USGS 7.5-minute maps. Reference the margins of the map where different quadrangle names will be listed for maps that are located directly east, west, north or south to the one you are holding.

Locate the map scale on your elevation map, which is usually found in the upper or lower margins of the map document. The scale will be composed of two parts including an actual scale bar and a ratio, such as 1:24000. The ratio 1:24000 means that every unit on the map is equal to 24,000 units on the ground surface. For example, 1 inch on the map represents 24,000 inches on the ground. The printed scale bar can be used to estimate the distances between landscape features on the map.

Practice estimating the distances between locations on the map that you are familiar with. If you have a topographic map of your neighborhood, use the printed scale bar to estimate how far your home is from a familiar landmark, such as a school, stream or post office. Compare your estimate to the distance you actually travel on the ground surface.

Study the contour lines on the topographic map. A contour line will be connecting all of the points in a particular area with the same elevation. Contour lines are drawn at different intervals depending on the map you are looking at. Note the contour intervals on your map. Most maps will have contour lines at 20- to 50-foot intervals.

Find an area of high relief that you are familiar with on your map. This could simply be a hill that you have walked on or driven up previously. Note how close together the contour lines are for an area with steep terrain. Now look at an area that you know to be relatively flat. The contour lines are spread much further apart from one another. Reading and understanding contour line patterns is the foundation for using an elevation map.

Learn what the different symbols shown on your map represent. There will be a detailed key printed in the margins of your map that you should become familiar with. Symbology will be used to represent mines, streams, caves, trails, different types of roadways, schools and churches. You may be surprised at some of the landscape features present in your neighborhood or in the area of the map you're studying.

Bring your topographic map with you as you visit different locations on the map. You will begin to see how useful being able to read an elevation map is. Reading the contour lines will reveal how steep a particular hill or other terrain feature actually is. Recognizing map symbols will alert you of streams, rivers, mines and other features of the landscape.

Use elevation maps of other regions you will be visiting before you actually visit them. This is especially important if you plan to participate in outdoor recreational activities, such as backpacking or hiking, in the area. You will be surprised at how much you already know about the landscape by using the elevation map beforehand. Continue practicing your topographic map reading skills to improve your knowledge and efficiency with this process.