When coupled with a GPS and compass, topo maps become even more effective tools for the outdoorsman.
by Bob Humphrey
One of the most valuable, yet frequently overlooked tools in any outdoorsman’s kit is a topo map (7.5' U.S.G.S quadrangle). Sure, a compass and GPS are great tools; but they become infinitely more powerful with this simple and inexpensive sheet of paper (or virtual image on your computer screen).
Before you ever leave home, you can visualize, then plan a route. Perhaps you want the shortest route, or the path of least resistance from point A to point B. The map will show you potential obstacles such as steep terrain, waterways or water bodies. In many cases, it will also show unimproved roads that you could use in the back country. Even if they’re long abandoned, they were built there for a reason.
Of course, you must first know how to read a map. The important information on a topo map can be broken down into what are sometimes called the five Ds: designations, directions, distances, descriptions, and details.
Designations include political boundaries such as town and county lines and borders of public land; names of towns, villages, churches, schools, and cemeteries. They also include features such as islands, points, mountains, rivers, ponds, and lakes; and public works or other descriptive notes like road names, golf courses, and radio towers.
Direction is fairly easy. On the map, north is up. South is down, right is east and left, west. To properly orient your map, lay a compass on the map so that the compass edge is parallel to east or west sides of the map. Holding the map and compass together, turn them so that the red north compass arrow is pointing to the top of the map. Your map is now nearly properly oriented and the direction to an actual location is the same as the direction to its corresponding location on the map. Bear in mind however, if you plan to use your map and a compass to navigate, you will need to know the declination (the difference between true north and magnetic north), which varies according to your location (see below).
Obviously, distance varies with map scale, and each map should have a distance scale bar printed on it. A standard 7.5' map, for instance, has a scale of 1:24,000, or 1 inch = 2000 feet. This translates to 1 mile = 2.640 inches on the map.
Descriptive information is, for the most part, in the margins of the map. The name of the individual map or quadrangle lies in the top and bottom right corners of the margin and is usually derived from a prominent designation feature in the area such as a town, lake or mountain. The names of adjacent quads are found in parentheses, at the top, bottom, sides, and corners. These names will be important when buying or ordering maps.
Last, but hardly least, are the details. Information about both man-made and natural features appears as various colors and symbols. Green indicates vegetation such as forest or shrubs. White represents open areas such as fields and croplands. Water appears as blue on the map - blue tint for waterbodies and large waterways, and blue lines for streams. Wetlands are identified by a wetland symbol (which looks a bit like a tiny flower). Wetland symbols on a green tint indicate a swamp, while those on a white background designate a marshy area.
Once you learn the basics, you can not only plan your route, but you can also plan a hunt by looking for features that may attract the type of game you’re after. Check back with us in the coming weeks for more tips on reading and using topo maps and aerial photos for planning and implementing a successful hunt.
A Word About Declination
You can save yourself some mental anguish by plotting declination on your map. Start at the declination diagram. Lay a ruler or other straight edge on the magnetic north line. With a pencil (never use ink!), continue the magnetic north line in the declination angle all the way up through the map. Then draw parallel lines 1 inch apart through the map. Your map will now be covered with magnetic north grid lines at 2000-foot intervals.