Topographic maps, or “topo” maps for short, are a 2D representation of our 3D Earth. You can visualize terrain you’re unfamiliar with by looking at a topo map, if you can read it.
Topographic maps can look intimidating with all their circles and seemingly endless squiggles. However, with an understanding of the symbols and information in these maps, and a little practice, you’ll be armed with an invaluable outdoor skill.
If you enjoy hiking and backcountry camping, use topo maps to route plan, estimate travel times, and find a good campsite. For the fishermen topo maps, or lake maps, will show you where a creek channel hits up against a point or flat. You can also see sudden depth changes. This of course can help you become a better fisherman and know where you’ll likely find fish. As a hunter you can use a topographical map to scout an area. You can find saddles and other areas deer are likely to travel, even if you’ve never been to the area before.
The first thing to look for when you open up your map is the map key. Using the map key, look for the compass rose and determine which way is north. If you choose to dive deeper into reading and navigating with topo maps, you’ll also note magnetic north and magnetic declination here. This is important for using your compass.
You’ll want to note the scale as well. In this example 1 inch equals 24,000 inches which is 2,000 feet. The scale is used as it is on any other map. More particular to reading topography maps is the contour interval. The contour interval in this example is 10 feet.
Interpreting Contour Lines
The squiggly lines on a topo map are called contour lines. Contour lines represent elevation. They each tell you how many feet above sea level a point on the map is. The number of feet between each contour line depends on your map. In our example there are 10 feet of elevation between each line.
You’ll notice that some lines are labeled with a number and others aren’t. If all of the lines were labeled, the map could get pretty cluttered! So that’s where your contour interval comes in. Every fifth line will be darker and labeled with a number. These darker, labeled lines are called index contour lines. To figure out the number that would be labeling the other lines you’ll use the contour interval. On this map if you see an index line labeled 4,000 ft and 4,050, you would just count by tens for the lines in between them.
If your map doesn’t tell you the contour interval in the map key, no worries! You can always figure out the contour interval yourself. Just take the difference and divide it by 5 to get the contour interval.
The closer contour lines are to each other, or the more “bunched up” they look, the steeper the terrain. When the lines are very close together the map is telling you elevation is changing quickly over a short distance. The opposite is true. There is a more gradual slope the further apart the contour lines are.
Topo Map Features
Something you might notice on a topo map is circles. When you see concentric circles you’re looking at what is a peak or a hill, depending on the map. (Of course, if you’re fishing bass, this is underwater and you’d call this a hump).
A topo map can also show a depression, like a crater, with circles too. If this were the case you’d see hatch marks on the circles. More likely than depressions, you might see cliffs or rims. You’ll notice that the lines are close together, indicating a sharp rise, just on one side.
You’ll also notice rivers and streams. Contour lines will bend in a “V” shape pointing to the source of the water.
Practicing With Topo Maps
Skilled hunters, fisherman, and hikers use a variety of maps to plan. Some maps show more detail than others. Some maps may not show certain features that another might. If you’re a hunter or backpacker you might practice matching what you see on your topo map to what you see in the field. Or practice by looking at the map of an area you’re very familiar with. If you’re a fisherman you’ll practice by trying to match what you’re looking at on your topo map with what you see on your fish finder.
Some of you will also want to move onto learning how to use your compass with your map to navigate. A good place to find some free topo maps to practice with is the USGS website. When you’re ready you can also buy topo maps.
With a little bit of practice you can make sense of all the squiggles on topography maps and use them to enhance your favorite outdoor activity.