Finding the Best Route on a Topography Map

Finding the Best Route on a Topography Map
Topography---or "topo"---maps are high-scale maps showing terrain features and elevation change. They offer the best insight into the terrain you want to cover and provide essential information about relief and slopes. Topo maps use contours, brown lines that represent a constant change in elevation, to map three dimensions in a two-dimensional representation. The closer together the contour lines, the steeper the terrain. On a typical scale of 1:30,000, where one unit of distance on the map is equal to 30,000 units on the ground, contours represent 40 feet in elevation change. Using a topo map allows you some familiarity with the terrain so you can plan your route through it.
 

Instructions

Difficulty: Moderately Easy

Map reading

Things You’ll Need:
  • Compass Topo map (high scale)
  • Compass
  • Topo map (high scale)
 
Step 1
Familiarize yourself with the map scale. The smaller the ratio, the higher the scale.
Step 2
Measure your proposed route, and calculate the over-ground distance. For example, a 1:25,000 scale means that each inch on the map is equal to 2,083.33 feet, or approximately 0.4 miles on the ground. Make sure your route is not longer than you are willing to walk.
Step 3
Pay attention to the contours. Check the map legend for the contour interval. If the contours represent 40-feet intervals of elevation change, contours one inch apart on a 1:25,000 scale show a slope of 2 percent. Contours a quarter-inch apart show a slope of nearly 8 percent. Make sure your route doesn't include slopes you are unable or unwilling to climb.
Step 4
Plan your route around and along contours. If you are walking directly up a slope, you will get more tired than if you follow the contour lines. Plan your approach by wider-spaced contours or up a ridge. Summits are represented by closed contour lines. If there are hashes on a closed contour, a depression is signified.
Step 5
Note the elevation listed on thick contours. If you are walking to a summit, subtract your starting point elevation from the peak elevation, as listed on the map. Dividing this by the distance of your route will give you your mean slope. The higher the number, the harder the gradient.
Step 6
Identify trails, which are typically represented by dashed black lines. Check the legend to familiarize yourself with the map symbols.
Step 7
Note the high points on the maps---the peaks in the terrain. Spot the cliffs, ridges and depressions represented by the contours, so you can plan appropriately.
Step 8
Identify streams and bodies of water. Streams are typically represented by blue lines on maps. They typically follow gullies and depressions, downward-facing V's in the map contours. First-order streams have no tributaries. Second-order streams have two tributaries. Third-order streams have two tributaries of second-order streams. The higher the stream order, the bigger the stream. Cross larger streams via trails that have bridges. Be certain of your crossing points.
Step 9
Walk ridges to avoid difficult vegetation.
Step 10
Note the tree line. Green areas on topo maps signify trees and vegetation.
Step 11
Avoid marshes and wetlands. On high-scale maps, look for marshes and wetlands in low-lying areas. Wet areas are typically represented by green half-asterisks. Don't try to walk through these unless you have to or are properly prepared.
Step 12
Always take a bearing on the map so you can be confident of your direction on the ground.
Step 13
Use the landforms and surrounding peaks to orient the map while walking.
Step 14
Carry a compass, and use magnetic north to orient the map correctly (paying attention to the deviation between magnetic north and true north as depicted on the map legend).
Step 15
Use a pace count to estimate distance traveled on the ground. Locate your exact position by landforms (streams, ridges, places) on the map or by taking a bearing on two or more visible landforms. The intersection of these lines on the map will pinpoint your position.
Step 16
Plan your route carefully. Be sensible about your abilities. Stay aware of each leg of the route, and be prepared before you start hiking.
 

Tips & Warnings

 
Draw your route in pencil on the map if you're off-trail. Stick to trails; they represent tried and trusted routes. Check the steepness of ridges along the ridge and off the sides. Avoid screes until you're experienced. Walk up first-order streams (gill walking) in impenetrable terrain.
 
Draw your route in pencil on the map if you're off-trail.
 
Stick to trails; they represent tried and trusted routes.
 
Check the steepness of ridges along the ridge and off the sides.
 
Avoid screes until you're experienced.
 
Walk up first-order streams (gill walking) in impenetrable terrain.
 
Planning a route is a good way to prepare for the real-world environment. But don't forget things the map cannot tell you, including weather and seasons. Know your area: Are streams bigger in winter or summer? Will there be ephemeral streams in gullies at the time of your hike?

Article Written By Benjamin Williams

Ben Williams is an award-winning reporter and freelance writer based out of Colorado. He has written for conglomerates of newspapers and magazines, supplying news, features, editorial and opinion. While running an Energy Services and Consulting firm, he now writes for multiple websites including the news site, Examiner.com.

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