A map is flat, but the world isn’t. We don’t walk, hike, or otherwise make our way across level, featureless plains with symbols painted on the ground. That would be boring. And maybe a little creepy.
The trouble is that many maps don’t treat the terrain they’re presenting as more than that. They mark key features and as-the-crow-flies distances, but don’t reveal the heights and depths that ripple the surface of the Earth. Getting from Point A to Point B could entail scaling a gentle hill, descending a steep mountain slope, dropping into a wash, or climbing a sheer cliff—something a simple “go north” won’t take into account.
You can have a working knowledge of how your compass works and a good grasp of general navigation, but that’s just the tip of the orienteering iceberg. To take things to the next level, you need to start thinking in three dimensions.
You need a topographic map.
Such a map reveals the topographic contours of the land, with lines that indicate elevation. These may appear as wavy, concentric blobs, and the more closely packed together they are, the steeper the terrain they’re depicting. The space between lines indicates a set change in elevation—say, 20 feet—and is known as a contour interval. Frequent darker lines are called index lines. Set at regular intervals, these index lines tend to be labeled with the actual elevation for ease of reading.
When navigating with a compass, you need to take these vertical changes into account. Moving along a path that rises a total of 35 feet over its entire course is a different endeavor than hiking a trail that goes up a couple of hundred feet and then back down—and then back up again.
A compass with a clinometer lets users determine the angle of inclination on whatever it is they’re sighting. Measuring the degree of a slope can help in planning the best route to a particular destination.
But keep in mind that topographic maps reveal a lot more that elevation. They can also show:
- geographic names. Many maps list this information, and for good reason. Place names matter. Why mess with a good thing? U.S Geographical Survey topographic maps tend to indicate everything from huge mountains and bodies of water to hospitals and cemeteries, which can aid in urban navigation.
- transportation data. Routes that get people and stuff from one place to another are generally marked with names and classifications. You can spot roads, train tracks, airports, and more. Established transportation corridors can serve as clear lines of travel for hikers, who may use them directly or reference them as a guide to be sure they’re continuing to head in the desired direction.
- land cover. Anything that sits on the surface can show up on a topographic map. The USGS makes use of a classification scheme that incorporates 21 different types of land cover, from urban and agriculture to perennial ice/snow. This is a vital feature for orienteering, since hikers who want to choose the ideal route may want to stick to, say, rangeland and avoid tundra. The next two more specific categories fall under the land cover heading:
- hyrdography. Think water—primarily lakes and rivers. The USGS refers to these specifically as surface waters. These features are distinct from wetlands, which get their own land cover classification.
- structures. This is a closer look at manmade buildings and similar projects. Some topographic maps display information on a structure’s footprint and even its function.
Topographic maps also reveal (as do most maps) the boundaries that indicate jurisdiction, from public parcels to federal property to tribal land. This can be vital to someone planning a hike, backpacking trip, orienteering event, or adventure race. Crossing onto private or restricted-access property can be a problem.
Also note that topographic maps will be labeled with a ratio scale, which indicates how a designated unit on the map (for instance, 1 inch) corresponds to a unit of distance in the real world (for instance, 1 mile). You should be able to find these ratio scales along one edge or another of your compass’s baseplate.
Want to get a sense of what you’ll be seeing when you head out into the charted wild? Topographical maps can be downloaded for free courtesy of the U.S Geographical Survey.