Follow the Lines

By Tom Cwynar | June 2, 1997
From Missouri Conservationist: Jun 1997

The author of a book I read in college claimed that Indians were never lost. They were always at home, wherever they trod upon the earth.

Reading those words prompted me to try to emulate Indian ways. I walked heedlessly into the big woods to become one with the forest.

It worked fine. I stalked, rambled, observed, turned over logs to see what resided underneath and crushed plant leaves in my fingers and inhaled the odors. During the course of a whole day, I never once gave a thought to classes, my unstable checkbook or my destiny in the world of literature.

Certainly, I didn't give a thought to where I was going, and when the sun started lowering toward the horizon and hunger began reverberating through my belly, I didn't have the foggiest notion which way led to my old Pontiac.

That made for a rough evening. Oh, I survived, although I was pretty achy the next day from all the walking, and I scratched my arms pretty bad while shinnying up a tree in the dark to look for car lights that would lead me to a road.

What I remember most about that woodsy experience, however, was the panic that threatened to overwhelm me. Although considered a pretty mellow guy, I broke a cold sweat and started running through the woods, even though I didn't know which way to go.

I remember shedding tears of frustration.

Modern day Indians needn't feel that way, even if they absolutely have to be home by five for supper. Thanks to more than a half dozen generations of "explorers" and another generation of satellites, we now have maps available that pinpoint exactly where we are and how to get home.

Maps describe counties, cities, countries, the planet. We've even mapped the moon, Mars and Venus. Those large scale maps may help space travelers, but more useful to us are the maps of small sections, conservation areas, corner woodlots, lakes - the areas you hike, hunt, bike and fish.

Some people admit to having trouble enough unfolding maps, much less reading them. That's understandable - maps speak a language of their own, representing physical features with nothing more than lines and symbols. However, with a little practice anybody can learn enough about maps to put them to good use.

Maps are necessarily smaller versions of what they represent and the amount smaller can be expressed as ratio, referred to as the scale of the map. For example, a 1:10,000 scale means that one inch on the map equals ten thousand inches of actual distance. In other words, one mile will take up a little more than six inches on the map.

A more common way of expressing scale is to say that so much distance on the map represents so much actual distance. For example,

1 inch might equal 10 miles or, on a more detailed map, 1 inch might represent 5 miles.

Likely the most universally used maps are those published by the United States Geographical Survey. These maps are available by mail through the USGS or at several authorized map dealers, often sporting goods stores or outdoor outfitters.

USGS maps range from a single map covering the entire state (1:500,000) to maps that take 2.64 inches to cover a single mile (1:24,000 or one inch equals 2,000 feet). You can contrast those numbers with the official State Highway Map of Missouri, on which 1 inch equals 13.5 miles or 855,360 inches.

The 1:24,000 USGS maps, also called 7 1/2 minute quadrangles, provide great and useful definition. They not only mark roads and railroad tracks, but also show buildings, cemeteries, landmarks, churches, creeks and springs.

Perhaps as important, the maps represent the topography or surface features of the land. At first glance, topographic maps look like the telephone desk pad of a doodler who's been three hours on hold. The placement of each one of those squiggly lines, however, imparts important information about the lay of the land.

The lines accurately depict hills, ridges, slopes, valleys and plains by representing exact levels of elevation. To understand how they do this, imagine a perfectly flat-bottomed cloud settling down to exactly 800 feet above sea level. Everything below that elevation would be clear and everything above foggy.

Lets say you ran a paint roller along the ground exactly where the fog line intersected the ground, including along the hillsides, perhaps circling a small peak and jogging in a bit where runoff has etched a gap into a slope. Imagine the cloud then raised 20 feet to 820 feet, and you drew another line. (For illustration purposes only; please don't attempt to do this at home.)

Later, after the sky has cleared, you get up in an airplane and take a picture of the area. Your paint lines on the two-dimensional photo would look exactly like those squiggly lines on a topographic map.

You can tell a lot about the lay of the land by the relation of those lines to one another. For example, if your two lines are close together, it would indicate a severe slope, since it only took a short space for a 20-foot change in elevation to occur. Lines farther apart would indicate a gentler gradient. Lines that jog in sharply would indicate a cut or draw. Lines that jut out indicate a point.

Topographic maps contain both index lines and intermediate lines. Index lines are darker and are periodically labeled with numbers showing the elevation at that line. Intermediate lines are lighter and often unlabeled. You can tell the elevation by counting the number of increments between index lines. The four lines between the 800- and 900-foot index lines, for example, would represent 820-, 840-, 860- and 880-foot elevations.

It takes a little practice to learn to use a topo map. You can simply study it over and over until you can visualize what every mark means, but the quickest way to become sharp with a topo map is to obtain one for an area familiar to you.

Compare a topo map that includes the family farm or your traditional hunting area to what you know about the area and what you can see. Look for ridges, brushy draws and steep rock walls. See if the map actually shows the easiest point to cross a creek. If you don't have such a home area, use the map on some open land where topographical features are easy to see. Spread the map out, look for far-off hills or peaks. See how a valley shows up on a map.

Traveling with topo maps

One thing a topo map can tell travelers is that a straight line is not necessarily the shortest or the easiest to travel distance between two points. When going from Point A to Point B, for example, skirting a deep valley is usually much easier on the heart, legs and emotions than is plunging down one side and scrambling up the other. And if you can avoid a stretch of boot-sucking marshland, you will arrive at your destination in much better shape and spirits.

When using maps to plot a course, you'll be well-served by an orienteering compass. You've probably heard of orienteering. It's a timed, cross-country competition, where participants follow a course, using a map and a compass. Orienteers are a pretty hardy and savvy group; they often refer to their sport as "cunning running."

The orienteering compass not only has the obligatory needle that points north, but also features a housing marked in 360° increments and an orienteering arrow etched on the bottom that can be rotated independently of the needle. These features are usually supported on a see-through base plate that has its own fixed arrow and an index mark for the housing.

Thanks to the earth's magnetic field, your needle always points north. (More on this later.) If you align the needle with the fixed arrow on the base plate of the compass and turn the base plate so 0° (north) is at the index line and trek off that way, you are trekking toward magnetic north and, given the inclination, could continue on your bearing of 0° all the way to Canada's Hudson Bay.

Let's say your travel plans were more limited, and you only needed to cross a timbered valley. You can see the lodge that is your destination from your ridge top, but once among the trees you'll lose your landmark.

To find a compass bearing that you can follow to the lodge, all that's necessary is to face the lodge and point the base plate arrow toward it. The floating arrow will still point north and you should then turn the housing to align the arrow on the bottom with the floating arrow. The number at the index mark will be your bearing.

Now, when you're in the thick stuff, all you have to do to remain on course is line up or orient the needle and the orienting arrow again, making sure that the same number is at the index mark. The base plate of the compass will now point out your line of travel.

If you try to travel while staring at the compass, you'll likely get a twig in the eye and scuffed up shins. Better to stop, use the compass to find a visible landmark-a distinct tree or rock, for example-and travel to it, then use the compass to find another landmark on the same bearing.

Because straight line travel is difficult, even under perfect conditions, use every opportunity, for example a forest opening or a rock promontory, to adjust the bearing to your eventual target.

Once you know the bearing from one object to another, you can always head toward it, even in dense fog or at night, and you can direct someone else to a target. If they have the proper starting point and the bearing, they will head in the right direction.

In order to find your way back, all you have to do is shift the index mark 180°, line up the north pointing needle and orienting arrow again and travel in the direction indicated by the compass base.

Now that we know how to travel over the landscape by compass, we can apply these same techniques to working with a topo map.

It's a great exercise and good fun to use a compass and map to plot a course at home, then take the compass out into the woods and try to follow the course precisely.

Since maps represent the land, you plot a course on them the same way. Here however, you don't have to use the magnetic needle at all, since on most maps, the top of the paper indicates north. Simply align the compass base with the direction you wish to travel, turn the compass housing so that the orienting arrow points toward the top of the map and read the bearing at the index mark.

In a perfectly machined world, we could follow the bearing we took on our map and reach our destination in the field. Our globe, however, possesses a seeming idiosyncrasy: the compass needle doesn't point to true north. Instead, it points toward an area near Hudson Bay, over 1,000 miles away from the actual north pole, to which your map is oriented.

What this means is that unless you're traveling somewhere near a line that runs through Florida and Lake Michigan, your compass and map will not agree. As you move away from this line, called the agonic line, the declination or angular difference between true north and magnetic north increases.

It only takes a bit of adjustment to accurately compensate for declination, however. USGS maps and many others include a declination symbol and the declination amount for the center of the map. If the agonic line is east of where you are, the declination is said to be easterly.

In Missouri, the declination varies from 5.5 to 6 degrees. This is important to know so that you can plot courses from topo maps, such as those on the back of conservation area brochures, that don't show declination.

When you make adjustments from a map to the actual route in the woods or fields, you have to subtract the declination. For example, if you use a map to plot a 52° course to a spring, a 158° course to a scenic overlook and then a 295° course back to where you started, your actual course, given a 6° easterly declination must be 46°, 152° and 289°.

An easier alternative is to change your map so that the bearings you take from it will be the same as those in the field. To do this simply take a ruler and with a pencil extend the magnetic north line all the way across the sheet, then space more lines across the map exactly parallel to the first line.

Now, instead of using the top of the map as north, let your new lines indicate north and adjust your orienting arrow so it is parallel to them. Since they are pointing the same direction as the needle in your compass will in the field, no addition or subtraction is necessary.

The words make it sound more difficult than it actually is to follow a compass course plotted on a map. After spending a little time in the woods with a map and compass and taking a few bearings, everything will fall into place and you'll be as comfortable in the woods as those Indians I read about.

And you'll have the added bonus of always being able to make it home for dinner.

Map Sources

Official U.S. Geological Survey maps are available through:

Missouri Department of Natural Resources

Division of Geology and Land Survey

P.O. Box 250

Rolla, MO 65401

(573) 368-2125


Distribution Branch

U.S. Geological Survey

Box 25286, Federal Center

Denver, CO 80225

Ask for a free index and a folder describing the symbols used in topographical maps. Maps cost $4.00 each, plus shipping.

District maps of Mark Twain National Forest lands are available for $3 each at U.S. Forest Service District Offices or by contacting:

Supervisor's Office

Mark Twain National Forest

401 Fairgrounds Road

Rolla, MO 65401

(573) 364-4621

Maps of conservation areas are available free on site or at nearby Conservation Department offices.

Conservation Department lands, state parks and federal lands are detailed in Missouri's Conservation Atlas. This large format book, which includes a road map for each Missouri county, is being revised and updated and will be available in late July. A detailed index shows what facilities, activities and fish and wildlife you can expect to find. To order the book send a check or money order for $15 (Mo. residents add 93 cents sales tax) plus $5 for shipping to:

ATTN: Fiscal Services Division, Missouri Department of Conservation, PO Box 180, Jefferson City MO 65102-0180.

Price is subject to change.

This Issue's Staff

Editor - Kathy Love
Assistant Editor - Tom Cwynar
Managing Editor - Jim Auckley
Art Editor - Dickson Stauffer
Designer - Tracy Ritter
Artist - Dave Besenger
Artist - Mark Raithel
Photographer - Jim Rathert
Photographer - Cliff White
Staff Writer - Joan McKee
Staff Writer - Charlotte Overby
Composition - Libby Bode Block
Circulation - Bertha Bainer