Outdoor Education: How to Read a Topographic Map

how to read a topographic map, topographic map

Before you’ve packed your bags, before you’ve gassed up the wagon, there’s the little issue of figuring out where you’re actually going to go and the type of terrain that’s there.

One of the best ways to do that is to peruse a map of the park or area that goes a little further than just showing you a layout of the park. A topographical map introduces you to the peaks and valleys and gives you an understanding of how difficult the terrain might be in the range of where you’re headed. It was originally developed as a way to depict counties and cities before the US Military used it in WWI.

To help you decipher and navigate your way through these complex maps, we spoke with Expedition Expert Cameron Martindell, who has completed journeys on just about every continent (including a four-month stint at the South Pole). When it comes to understanding terrain, his knowledge is invaluable. Here are his tips on how to read a topographic map.

cameron martindell, how to read a topographic map

Photo by Cameron Martindell at Whitetail Peak, Beartooth Range, Red Lodge, Montana 

Step 1: Get The Map

It used to be that you’d have to go to an outdoors store or a well-stocked library to look at and copy multiple pages of a topographical map; trails would stretch across pages and it was a time-consuming process.

Now, there are a few great apps that Martindell uses as his primary topographical sources:

  • View Ranger: Uses augmented reality to identify mountains and trails, while offering downloadable maps.
  • Gaia GPS: Offers easy-to-read maps and creates shareable maps for friends and other adventurers.
  • Avenza Maps: Delivers a 1:24,000 scale USGS map for the entire USA.
  • OnX Roam: Shows a combination of points of interest and other features over one map level.

However, Martindell stresses that the only surefire way to be safe in the wilderness is to have a paper copy of the area where you’re headed. “Sometimes, even software updates can zap your saved maps,” he says. “Plus, a printed map doesn’t need batteries.”

For paper maps, he recommends CalTopo, which has detailed maps that can be optimized for printing. You can hone in on a specific region and efficiently capture a desired area.

You could even get a map printed on a durable scarf, which serves double-duty on the trails.

Step 2: Read The Map

It’s important to understand the scale of the map when analyzing it. “On a paper copy, does an inch represent a mile, maybe 10?” he says. It’s also important to note the contour interval–or distance in vertical feet between contour lines. For any given map, the contour interval is always the same within that map.

topographic map

The brown lines weaving all around the map are known as “contour lines.” Each contour line represents a single elevation, meaning, no matter where you put your finger, as long as it’s along the same continuous line, it will always be at the same elevation.

On the map, if contour lines are close together, then it represents a steep incline, like a mountain. If the lines are farther apart, then the terrain is more level. Martindell notes that careful attention must be paid to determine where the breaks in the lines are. A change in contour could be anything from a basin to a valley. ‘When lines form a v shape, it can be difficult to recognize the difference between a ridge and a ravine,” he says. On that subject, in areas where there are peaks, hills, and mountains, contour lines can form large concentric circles that grow smaller the higher the elevation and vice versa. So, be aware that, much like the difficulty in recognizing the difference between a ridge and a ravine, so too can there be difficult in telling apart a mountain from a circular depression or valley.

Step 3: Before You Go

Learn as much as you can about the terrain where you’re headed. “Trails can be mismarked and signage may not be what you expect it to be,” he says.

Knowledge is really power when it comes to reading and getting the most out of a topo map. You’ll be able to plan timing and exertion for the trail. “A rough estimate is two miles per hour walking plus an extra hour for every 1,000 ft. in elevation gain or loss,” he says.

And always carry a compass.