|NATIONAL PARKS QUICKLINKS|
Backpacker Magazine – June 2001
How one perpetually disoriented hiker found her bearings, thanks to some backwoods navigation pros.
"USGS maps are good for hikers who want to stay on known trails," observes U.S. Army Special Forces Instructor Sergeant Joseph McPeak, "but they aren't accurate enough for the military because they don't show enough detail of the terrain."
That's why the armed forces use special military topos, most of which detail the terrain around military bases. Similarly, orienteers use unique, highly detailed maps that cover competition courses.
So what's a backpacker to do if he or she wants a better map? Here are some options:
- Research what maps you'll need. First, ask the area's land manager what topos-USGS, USDA Forest Service, regional-best show the trip you're planning. Also, check regional hiker's guidebooks and Web sites. USGS topos are available at http://ask.usgs.gov; check to be sure you're getting the most current map. The Forest Service and USGS are jointly producing 7.5-minute Forest Service Single Edition maps, which show more detail and features such as trails and campsites (303-202-4200; $4 each).
- Check the quality. Take a good look at the contour lines on a map. Are they crisp or fuzzy? Poor offset reproduction or printing from a digitized format often causes the contours to blur, which makes translating the lines into real-life topography difficult. If you print a map on a computer printer, spray it with aerosol hairspray to keep the ink from running. Ideally, contour intervals should be as small as possible (showing 40 feet, for example) for easy reading, but such detail may take up too much space in maps of places having dramatic elevation changes.
- Determine the best scale. Off-trail travelers need maps that are 1:24,000 scale, also known as 7.5-minute maps. One inch on the map equals 24,000 inches, more than one-third of a mile, on the ground. If you're sticking to established, well-traveled trails, 15-minute maps (1:62,500 scale) probably will be adequate. On these maps, 1 inch equals 1 mile on the ground. The USGS's 7.5-minute topos generally are more current than their 15-minute maps.
- Check the date. It's usually printed in the lower right-hand corner. The older the map, the more questionable the accuracy of the routes.
- Annotate your own maps.
If the most recent topo is outdated, update it yourself using information from recent guidebooks, land managers, and digital images that can be downloaded from the Web. A joint program of USGS and Microsoft Corporation called the Digital Backyard gives Internet users access to a variety of digital resources, including online quads, aerial photographs, and satellite images. The USGS's aerial photographs, which are updated every 5 years, and orthophoto quads (3.75-minute-square aerial photographs modified into a maplike format) may show features not shown on topographic maps. The latter also can be used to accurately measure distance.
U.S. Geological Survey contacts
Aerial photos and orthophoto quads
Customized map publishers
Still can't find the map you need?
Many regional trail clubs customize maps for their area. To find clubs located in the region you plan to hike, contact the American Hiking Society at (301) 565-6704 or visit www.americanhiking.org.
For more information about the sport of orienteering or to find links to local orienteering clubs, contact the U.S. Orienteering Federation at www.us.orienteering.org, or P.O. Box 1444, Forest Park, GA 30298-1444.