how to read a map

Terrain Association

As a young marine, I heard “Left add, right subtract!” more times than I could count. And here I thought I joined the Marines to avoid math!

Land navigation was a dark voodoo to me then.  So many rules, numbers, variables and oh so many tools (compass, protractor, DAGR, Garmin GPS etc).  With time and practice, I grew to not only understand it but feel a level of comfort and confidence in the woods because of this very necessary backcountry skill.

My intent with this blog is not to talk to the basics of orienteering .  I recommend you seek out a good class and get your Google on and find some good solid sources (link: http://www.rei.com/learn/expert-advice/navigation-basics.html) to read up on contour lines, declination, map symbols and compass work.  The focus of this article will be terrain association, a very specific skill that I find most helpful.

Terrain association is the practice of comparing  major terrain features against what is visible on an oriented (basic skill) map.  The navigator has a number of options to pick from when doing their assessment of the terrain in an attempt to orient their present location and upcoming route.  The major terrain features on a map include hilltop, valley, ridge, depression, and saddle.  These prominent terrain features are not however the only option.  Water sources like lakes and rivers are also good indicators.  Simply walking down the trail and seeing a hill top to the left and a pond to the right a hiker will likely be able locate that combination easily on a map.  Streams are somewhat variable, but finding a dry stream or river bed is still a clue to your location.

Other features on the map include the use of vegetation or lack of (fields/meadows),  Understanding the symbols on the map, the traveler can easily ascertain a vineyard, orchard or farm. Unlike the more variable nature of vegetation or small water sources, man made features on the map are a huge help in terrain association.  Roadways, firebreaks and buildings are terrific indicators when they are marked on your map.

Always remember in planning a hike seasonal changes will impact your terrain association methods and abilities.  Snow sometimes makes terrain features more prominent, while obstructing micro terrain.  Thicker canopy or vegetation in summer months will obscure your view and droughts will wilt vegetation and dry up water sources.  Also take into consideration that this is 100% visual tool, so times of lower visibility will negatively impact your reliance on this method of travel (have a compass and GPS if you can – two is one, one is none).

Melanie and I have relied heavily on this skill on all of our trips.  It is not foolproof by any means.  We were presented with two trail heads about 10 feet apart in Yosemite.  We took what we thought was correct.  It turned out the route of the two trails paralleled each other in a manner that didn’t allow us to determine we were going the wrong way for miles.  Both trails hit the same ridge lines, similar switchbacks, the same water sources etc. No harm done.  We just had a nice visit to Sunrise Lakes campground BEFORE we did Clouds Rest.

Some best practices for effective terrain association include:
  • Know the basics – you don’t need advanced orienteering skills, just a grounding in the fundamentals of map reading (understand all those dang squiggles and symbols)
  • Map Study – pore over your map before you depart – not only does it get you acquainted with your route, but will better prepare your training, gear selection, etc.
  • Consult your map early and often – don’t set off from the trail head and look at it when you are not sure of your location – comparing the ground truth you are experiencing with what that map says is critical to stay oriented, know your pace and understand what is coming up (ex. will I need my trekking poles to get past this water source and / or fill up)

I recommend you start out slow with a trail you are familiar with to work on your skills and remember that navigation is a perishable skill so keep yourself sharp.

Hope this helps.  Stay Safe.

Advertisements

2 thoughts on “Terrain Association

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s