"Once you're outdoors, you can't rely on technology anymore," says Christiaan Adams, developer advocate for Google Earth. Beingness able to read a proficient erstwhile-fashioned paper map is one of the well-nigh fundamental outdoor skills. In case you never learned or need a refresher, here are the basics.
(Want to larn how to take this noesis to the side by side level, and take advantage of the total capabilities of 21st century mapping tools?)
Types of Maps
Google Maps tin can be considered a basic street map: an accurate two-dimensional portrayal of the globe that includes the locations of roads, cities, parks, and other features. Maps like these do null to illustrate peak.
That'south where topographic (ordinarily merely "topo") maps come in. These have lines at set up elevation distances that trace the contours of the terrain. Past representing topography, they let you to see the three-dimensional world on a two-dimensional piece of paper. Topo maps are the only map y'all should use if you're trying to navigate outdoors and will be the subject of most of this article.
There are likewise oversimplified trail maps—recollect stylized theme-park maps—that may loosely represent the location of a trail and points of involvement in relation to each other. Avoid these at all costs, equally they lack the necessary topographic data that will allow yous to notice your way if lost.
You tin can notice nationwide topo maps from the U.South. Geological Survey (USGS). They're the golden standard and the basis of many other commercially available maps.
Understanding the Legend
A standard legend on a USGS quadrant map. Legends on other types of maps will exist similar. Photo by USGS.
Any good map will tell you how to read itself. Take the in a higher place legend from a standard USGS quadrant map. From left to right, it gives you data on where and when the map information was compiled, the area'southward magnetic declination, the calibration (annotation the contour interval below information technology), the location of the shown area in relation to the state it's in (in this example, Texas), and a key to the symbols used to represent roads. Permit's look at what this information represents and how yous can use information technology.
The source data isn't typically all that relevant. It's worth glancing at merely to make sure it'southward not insanely out of appointment, but every bit nosotros can see hither, much of the data used to assemble this map comes from 2008–2015, then it's pretty recent.
You lot're looking at a magnetic field created by our planet. Information technology determines how many degrees off magnetic n your compass will read. Photo past USGS.
Magnetic declination is the difference between truthful northward and magnetic n. A quality compass will allow you to alter the management it points to suit the data provided by the map. Follow your compass instructions to practise that. As you tin see, there can be some pretty large differences betwixt the two norths depending on where in the globe you are.
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The scale is how much the represented area has been shrunken down from the real world. For well-nigh topo maps, information technology'll exist 1:24,000. So, one inch on the map would be 24,000 inches in the existent world. The ruler represents distance to make the scale easy to understand at a glance. Desire to measure the altitude of a winding trail? Use a slice of string to trace its route, mark its length, then compare the straightened string to that calibration. Or do what I exercise: Use two fingers as a protractor to "walk" rough distances across the map.
The contour interval is the top altitude between each of the contour lines, so y'all tin scale the terrain being represented.
The map location is obvious. Information technology allows you to easily look upwardly the adjoining maps, should you need them.
The fundamental is some other essential, spelling out what the symbols on the map represent. Hither, information technology'due south types of route, but yous'll too discover stuff similar the lines that correspond hiking trails, or train tracks, or watchtowers, or other essential stuff.
Have a minute to absorb the fable earlier trying to read the map itself. It'll make the experience manner easier and more informative.
How Contour Lines Represent the Real Earth
Here comes the catchy part. Information technology may seem hard at commencement glance, but once you learn what contour lines represent, y'all'll be able to expect at them and picture real-life mountains, valleys, or any. And once you can do that, you can use a map to speedily and easily find your location and navigate.
Adams, who also volunteers for the Bay Surface area Mountain Rescue Unit, rescuing lost and injured travelers across California, says he nonetheless uses Google Earth to gain an understanding of an area's topography and terrain features earlier diving into a topo map and suggests that doing the same might be the best mode for y'all to acquire.
"I can do my map and compass work improve and more finer if I've seen the satellite imagery and the digital maps first," says Adams.
Let'southward do but that, using Devil'due south Tower National Monument as an example. Its distinctive shape should make seeing it represented with contour lines piece of cake to sympathize.
Devil's Belfry is a prominent i,200-foot butte that rises from Wyoming's plains. You'll recognize it from "Shut Encounters of the Third Kind" and those mashed potatoes. Photo from the U.S. Department of the Interior.
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This is what Devil's Tower looks like on a standard road map, in this case Google Maps. Yeah, you tin make it out because it's named, and considering a hiking trail surrounds it, simply you can't make out any terrain features at all. Photograph from Google Maps.
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Hither's Devil's Tower photographed from a satellite and displayed in Google Earth. Now you're starting to see what its terrain might look like, viewed from the top, looking down. Photo from Google.
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And here is Devil's Tower on a proper USGS topo map. You lot tin can immediately see how much more information is available, describing fifty-fifty hitherto unseen terrain features surrounding the butte, which rises steeply in the middle of the map. The farther apart the contour lines, the more gradual the slope; the closer they are, the steeper the gradient. As you tin run into in the photograph upward top and on this topo map, Devil'south Tower rises almost vertically. On this map, the profile interval is 20 feet, significant each line is twenty vertical anxiety from the next one. You lot can see valleys formed past contour lines making a "V" pointed uphill, while ridges make a "V" pointed down. Peaks are represented by rough circles, equally on Devil's Tower. Photo from USGS.
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Finding Your Location
Any compass yous want to utilize for navigation should look similar this one. The prominent black pointer on the front is the direction of travel arrow. Inside the bezel, you can see the declination adjustments and the orienting lines. It also includes a scale for standard 1:24,000 topo maps, merely to make estimating distances that much easier. Photo from Silva.
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Pick out two singled-out terrain features that y'all can meet both in the real world and on the map. A mountain peak, a prominent bend in a river, a saddle in a ridgeline, or something similarly unique.
Hold your compass level, point it (via its management-of-travel arrow) at the first object, and twist the bezel so the large red pointer within it aligns with the scarlet north needle. Next, locate that object on your map, and residuum a long edge of your compass on it, with north yet inside the ruby-red bezel arrow. Rotate the map until its orienting lines marshal with those of the compass bezel. Trace a direct line through that object, using the edge of your compass every bit a ruler. Y'all're somewhere on that line. Do the same for the second object, and where that new line intersects the showtime one is your precise location. Go this correct, and you've just found your location as accurately and quickly as you could with a GPS navigator.
Of grade, you can do this calculation mentally once y'all proceeds some experience interpreting maps in the existent world. "I'g right past that river bend," or "We're but under that ridge," will simply go second nature.
Adams suggests that the easiest manner to learn this skill is by first using Google Maps on your phone equally a fill-in. Try to guess or calculate your location, then check it confronting the blue dot on your telephone. He again cautions, all the same, against relying solely on that technology.
"When information technology comes down to it, digital maps are extremely useful," Adams says. "But you nevertheless need to know how to get yourself out of problem the old-fashioned way."
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