Everything You Need to Know About Reading a Topographic Map

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A step-by-step guide to buying and using topo maps

If you enter the wilderness, at some point or another, you’ll be required to read a topographic map (often called topo maps). Reading topographic maps for wilderness adventure, research, survival, and navigation is critical—especially as a precautionary measure—for safety and comprehension of the terrain and landscape. To master land-interpretation, navigation, and survival, I always recommend using a printed topographic map and a compass. Bring a smartphone, GPS unit, downloaded maps, a pre-charged battery-pack, and a solar charger to step up your capabilities.

What Is a Topo Map?

Topographic maps present realistic information and a view of the landscape, unlike a regular (road) reference map. Topographic maps are used professionally and recreationally. The primary feature of a topographic map are the contour lines. These lines show changes in elevation and are layered with a variety of information describing the terrain—such as rivers, creeks, tree coverage, power lines, streets, trails, and more.

How to Read One

Topo maps provide a lot of information in a small amount of space. But reading one isn't hard. You just have to understand the contour lines, colors, and symbols. Here's the breakdown:

Contour Lines

Contour lines–usually curved, parallel brown lines–show the shape and elevation of the land by connecting points of equal elevation. When reading contour lines, you can easily visualize a three-dimensional shape on a two-dimensional surface. The space between the contour lines is called the contour interval and represents a specific (set) distance. If the contour interval is 50 feet, the vertical space between the two contour lines is 50 feet. You can usually find the contour interval on the map legend or by subtracting the lowest elevation from the highest and dividing the total by the number of contour lines between the two elevations.

When contour lines are close together on a map, it shows a steeper slope of the terrain. In contrast, when contour lines are far apart, it shows a flatter terrain. The thicker, sometimes darker-brown, contour lines with an elevation number denoted are called index contours. These index contours are usually shown in increments of five. (i.e. If contour interval=50 feet, index contour interval will=250 feet). Occasionally, a cartographer will include a shaded relief image with contour lines to help accentuate the underlying topography.

The contour lines on this USGS 7.5' quad help us easily distinguish the ridges–and associated valleys–around Mt. Young and Mt. Hale

Thanks to labeling on the darker-brown index contours, we can easily estimate that the saddle between Mt. Chamberlain and Mt. Newcomb is between 3,880 meters and 3,900 meters.

Mt. Whitney, the tallest peak in the Lower 48, stands 14,505 feet tall, or 4,416.9 meters as labeled on this USGS 7.5' quad. Note that Whitney's eastern slopes are much steeper (tighter contour lines) than its western flanks (contour lines more spread out).

Colors

Cartographers generally use the same, intuitive colors and styles to graphically communicate what you’ll encounter in the world. Usually, tree-covered and vegetated areas are green, water features are blue, and shades of gray (and black) will be used for human-made features. Contour lines are usually depicted in brown.

Symbols

A topographic map uses symbols to keep the map legible and less crowded. Common symbols include campgrounds (tent), mines (pick-axe), schools, towns (circles), places-of-worship (crosses or stars), and elevation markers (x-marks-the-spot!).

What to Look for When Buying a Map

There are a few key factors to consider when purchasing a map. Ask yourself these questions to make sure you're getting one that will best suit your needs.

1. Are the scale bar, legend, north arrow, and publication date all on the map? This is probably one of the most important, and overlooked parts of purchasing. You don’t want to be caught on a five-day trip, in bad weather conditions, with a map that’s 15+ years old (like I did once).

2. Will you need a waterproof and tear-proof map? The answer depends on how and where you intend to take it. A paper print-out from your home printer may suffice for a short, sunny day-hike.

3. Was the map designed for three or four seasons? When hiking in regions with high annual snowfall, check to see if your printed map lists all trail types for various uses. Sometimes, a three-season hiking route differs from a snowmobile or skiing route in the same area.

4. Did the cartographer include supplementary information about the area? Look for camping or wilderness regulations or amenities and utility services nearby. This supplemental information can prove useful in the planning stage of your adventure, or in case of an emergency.

 

Get Familiar with Your Map

Now that you speak the language and have one of your own, it's time to put your skills to the test. Try these exercises to get to know your topographic map a little better:

1. Practice folding the map. Use creases to your advantage to help better understand .

2. Locate the north arrow and declination. Most maps are designed with north facing up on the page. Be aware of your north arrow because when making maps, a cartographer has to choose between True North and Magnetic North. If the map is designed with True North, there should also be a declination annotation for the magnetic field of the earth. This is the number of degrees adjustment you have to make with your compass when using your map in the wild.

3. Look at the scale bar. Every topographic map is created to a specific scale. The scale is always a ratio of map distances compared against actual distances for two points. For example, “Approximate Scale 1:24,000” means one centimeter on the map is equal to 0.24 kilometers (24,000 centimeters) in the real world. U.S. Geological Survey (USGS) Topographic Quadrangle Maps are made with a scale of 1:24,000.

4. Inspect the contour interval. The contour interval will vary, depending on the scale and the cartographer’s choice.

5. Look at the legend or key. Symbols are defined in the map legend. Symbols and icons help identify map features without congesting the map. If you’re using the USGS Topographic Quadrangles, reference this PDF for their library of map-symbols.

6. Identify your route and key landmarks. Taking a bearing is probably the most effective way to use your map as a valuable tool. A bearing is a reading of direction (in degrees) from your current location to another object or location. Bearings can be used to orient yourself on the map in relation to key landmarks and your intended route. The best wilderness survival experts can associate map features with what they see from the ground without a compass—just the map. This spatial reasoning takes time, energy, and practice; I recommend you start practicing with both a compass and your topo map.

For more information on how to read and use a compass. See these resources:

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