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Maps: How to Orient a Map to the Surrounding Terrain

Maps are invaluable for navigating unfamiliar terrain, but without this basic step, you might just be spinning in your tracks.
Photos by Jennifer Howe / howephoto.us
  • 1) You're looking at the land, and your map, but it's still easy to get turned around. First, orient your map properly to True North (TN). Then you can correlate paper landmarks to real ones.
  • 2) Geographic North, at the North Pole, equals "up" on maps, but compass needles point to the Magnetic North Pole (MN). The difference in angle, called 'magnetic declination,' is shown at the lower left of most map quads.
  • 3) While small in the U.S. Midwest, the magnetic declination angle gets very large in places like Alaska (MN = 28 degrees E of TN) or Maine (MN = 20 degrees W of TN). This unadjusted compass would put you 15 degrees off using the map shown above.
  • 4) Any compass worth using has an adjustable magnetic declination. Some are simple friction twist adjustments. This one uses a small screw on the needle capsule.
  • 5) Properly adjusted for 15 degrees East declination (southern Utah) the compass looks like this. The needle points to MN. The compass navigation lines point to TN.
  • 6) Put the compass "upright" on your map quad. Be aware that many grid lines on maps (survey lines and UTM grids) don't point to true north. Map borders always do.
  • 7) Rotate until the compass and map come into alignment. Now you can look around to see how directions and landmarks correlate.
  • 8) An example in confusing terrain: The mapped canyon runs north, but it twists and bends. Orienting the map properly looks like this, even though the canyon seems to be oriented wrongly.
  • 9) Looking closely, the map reveals you're at a western bend in the canyon. But you need to follow your progress to know roughly where you stand. With a GPS and coordinate-gridded map, you could pinpoint your position AND accurately orient to landmarks.
1) You're looking at the land, and your map, but it's still easy to get turned around. First, orient your map properly to True North (TN). Then you can correlate paper landmarks to real ones.
Image 1 of 9

1) You're looking at the land, and your map, but it's still easy to get turned around. First, orient your map properly to True North (TN). Then you can correlate paper landmarks to real ones.

READERS COMMENTS

Page 1 | 2

I am sure this is very helpful if you already know how to use a compass to orient yourself! I don't and I am trying to learn and this is a tutorial that is frustrating and useless.
— Cathy

To Cathy,

Start with learning to read a compass and a map. I'm sure it would frustrating trying to learn calc without learning basic math first as well. Same concept. Good luck and safe travel!
— Matthew

Are you kidding me? The only thing frustrating and useless is Cathy's comment. Good article, thanks!
— Aaron

If your compass doesn't have an adjustable magnetic declination, just add or subtract the declination given at the bottom of your map. To know whether to add, or subtract, the military mnemonic is "Maggie goes to Grid right after a lustful shower - MGRALS". Meaning, "when converting magnetic azimuth to grid azimuth, if the declination is to the right, add the degrees. If to the left, subtract.
— Tom

Cathy, A classic reference is by Bjorn Hjellstrom's "Be an Expert with Map & Compass: The Complete Orienteering Handbook." This book really helped me when I learned compass use. Also, check with your local SAR or Community College---Orienteering is a growing hobby and they often offer classes on compass use/GPS, etc.
— CanyonRam

This was helpful to a point for me. I am getting lost around the declination. My compass does not have an adjustable magnetic declination. I get that I need to do the math, but (I feel really stupid asking this) am I supposed to turn the map so that my true north lines on the map are now lined up with the magnetic north + or - what the declination table indicates? I am definitely going to need more practice with this. haha =)x
— Lisa

This was a pretty good slide show, but it still is difficult to describe to a novice (like Cathy). A series of orientation exercises in the field will solve the problem, if a good instructor can be found. It might take a few tries, but soon the light will go on!
— Mike

I took some mapping and surveying in college for a forestry program. They always said think peaks and creeks. You can look off in the distance lie across a canyon and pick up large features like a mountain peak and with three in view you can easily triangulate your position.
— Mark

I find it much easier to draw a magnetic north line on the map and align the compass baseplate to it and do the orienting. This way you don't worry about compensating for the declination. It's compensated for in your mag north line. Also you don't need to memorize any silly mnemonics. I always check the current declination for the area using the NOAA declination calculator. If you are using a USGS topo the declination may be out of date. It's not constant.
— Vince

#7 a bit confusing otherwise good article. Backpacker magazine articles are always helpful but I wish they would make it possible to print just the article information and/or photos without the rest of the page information.
— Deano


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