Map, Compass & GPS

Map, Compass & GPS
Wild flowers along Fall Creek on the way to the Green Lakes - Oregon

Sunday, November 29, 2015

Terrain Association

“A good view will help to form a picture of the shape, the patterns and grain of the land itself.  High ground will tell a story of the geological formations and erosion.”
                                    The Natural Navigator by Tristan Gooley

Terrain association is a key step in land navigation.  While the topographic (topo) map identifies terrain features through the use of contour lines, colors and symbols, terrain association is a process of confirmation of map to land features.

In the field a key step in terrain association is to orient the topo.  Orienting a map is a starting point to identify where I am, where I want to go and where I have been.  When oriented, map north will match geographic north on the ground. For information on how to orient a map read my supporting post.

 I orient my topographic map (topo) before I leave the trail head and at regular intervals during a hike.
It is a process where I involve both map and compass.  Of course, orienting a map can be done without a compass and done visually.  I find using a compass takes just a tad more time and the more hands on time with the compass the better. 

A key component of terrain association will be the evaluation of the information provided by the contour lines.  Contour lines identify five key terrain features that include hilltops, valleys, ridges, depressions and saddles.
“Match the terrain to the map by examining terrain features.”
                                    US Army Field Manual FM 21-26 Map Reading and Land Navigation
Gain a clear view of the land in the immediate area before comparing map to ground features.  If needed get an elevated view of the surroundings.
While looking at the map, I break down the terrain and lay of the land into two components that I refer to as pathways and boundaries. 
Pathways make up my route through the backcountry.  Pathways are trails, old “jeep roads,” government roads (e.g., Forest Service and Bureau of Land Management gravel and unimproved roads.)  Not all trails and roads are pathways.  In an area lacking trails and roads, an open area clear of significant vegetation may be a pathway.  Similarly, a valley or ridge line might be a pathway too.  Importantly, the pathway will be in the direction of desired travel.  Finally, the hiker needs to ensure the pathway is safe and he is physically up to the task. 
Trail guide books are an excellent source for finding a pathway.  Many of the newer publications offer coordinates for the GPS receiver, map views and a description of the recommended route.

Boundaries are major land features that help guide the hiker along his path too.  They are features that provide containment and may prevent the hiker from going far off track.  Boundaries can be rivers, streams, rail road beds, roads and large features such as a mountain range or ridge line.  Boundaries keep the hiker within the route of travel.  For example, if a stream is crossed then perhaps the boundary has been violated.  

Figure 1 In the image above the blue line is the pathway with the borders and boundaries in red.

In the image above the blue line mirrors an existing trail and is a pathway.  The two red lines border steep terrain and are the boundaries for this hike.

Start the terrain association process at home.  By reviewing the route on the kitchen table one begins to develop a mental map.  Maps reviewed with trail guides and conversations with those knowledgeable of the area improve the hiker’s familiarization of the backcountry pathway; this is the detail that improves and supports navigation.  The refined mental map aids in the correlation process while in the field.

Practice and frequent review makes the task of terrain association simpler over time.  Involve children in the process too.  They will be your future navigators.


Wednesday, November 25, 2015


My guests are arriving early for Thanks giving dinner.

Tuesday, November 24, 2015

Suunto Compass Review

A good friend alerted me to Sectionhikers' post about the Suunto M-3D compass.

"The Suunto M-3 D Compass is a baseplate style adventure compass with a declination adjustment that is optimized for use in forested or mountainous terrain where you can rarely see your destination. I’ve been using mine for 4 years, ever since I became really interested in off-trail hiking and navigation and started teaching those skills as a instructor for the Appalachian Mountain Club."

To read the complete post go here.

The Suunto M-3D is a super compass.  Think of it as a rugged scientific instrument.

This is a great choice for a Christmas present.

Wednesday, November 18, 2015

GPS Battery Power

In 13 years of teaching GPS classes I have had very, very few reports of a GPS receiver breaking or failing electronically. What I do hear about is battery power draining at the worst time.
I’d offer a few suggestions:

  • Batteries will generally last for a reported 20 hours of continuous use; more on that shortly.  If you just turn it on, mark a waypoint, and turn the receiver off, the batteries will last quite a while.
  • I prefer the Duracell and COSTCO alkaline batteries.  I have found that cheap batteries don’t last as long and require replacement more frequently.
  • If a GPS receiver can use Lithium batteries then consider that option and do check the owner’s manual.  Lithium batteries are more expensive but last longer and work better in cold temperatures (down to -40°F).
  • Carry a spare set of AA batteries.
  • I keep fresh batteries in my GPS all the time.  That said, because of my SAR responsibilities and the frequency of my trips, fresh batteries are always loaded.  It’s my personal preference that “works for me.”
  • If you have an older receiver such as the Garmin 12, keep batteries in it always.  The four AA batteries keep the internal lithium battery charged.  The internal lithium provides power to retain saved waypoints and tracks.
  • Features such as the backlight, audible tones and electronic compasses drain a set of batteries.  On many models the electronic compass can be turned off by pressing and holding down the page button.  Manage your power needs.
I don’t have a baseline for rechargeable batteries.  My suggestion would be to keep extra’s on hand and really “wring them out” over a full day to see how well they work.  Do this before your trip afield; remember, it has to work for you.

I keep my GPS powered up all day when in the backcountry.  I download my track and waypoint data at the end of a hike to my Terrain Navigator software. This gives me the best historical record of my outing.  Usually batteries become drained after a full day and it just easier  to change them out as I get my gear ready for the next day.  

A fully charged GPS is a wonderful tool that complements your backcountry experience. Remember, even though you have the latest and best receiver, always take that map and compass on every trip.

Monday, November 16, 2015

Dangerous Weather in the Backcountry

In the field forecasting is an important skill for the backcountry hiker.  Learning the basics is an important first step.

Let me begin by stating that forecasting begins at home.  Monitor the local news and the cable weather channels to get a broad, general idea of the weather conditions before hitting the trail.  Further refine that information by checking inter net sources such as and the National Weather Service’s site
My “go to” reference is Northwest Mountain Weather by Jeff Renner (published by the Mountaineers.)   Renner is a professional meteorologist and broadcaster, an outdoorsman
and flight instructor.  Northwest Mountain Weather provides a superb overview on how “the weather works” in the Pacific Northwest.  Uniquely focused to this region, this book provides an overview on climate and weather, local weather patterns, snow and avalanche conditions, and provides many charts and data sources.  My favorite part of the book is Chapter Seven’s “Field Forecasting Guidelines.” This chapter identifies what to watch for and monitor while in the backcountry.  

The balance of this post will focus on what to consider about hiking during periods of thunderstorm activity.

The dark clouds of a thunderstorm provide a strong sense of mass and energy.  They can be seen a long way off.  Avoid them when possible.

As a storm develops you will notice that the clouds may change shape, grow taller and darker.In many cases an anvil shaped cloud growing tall and developing a distinct leading edge maybe observed.  This is a sign that a storm is on the way.

Lightning is the predominant killer associated with a thunderstorm.  Roughly 40 people are killed each year and approximately 240 are injured.  Visit the National Weather Service’s site for more information about lightning safety;

The ideal action to avoid the danger of a significant storm is to get out of the weather.  Leave the field for the safety of a building or a car.  Caves can provide shelter but must be deep and dry.  A shallow cave offers almost no protection.
Renner’s guide lines and actions include:

            “Do watch for cumulus showing strong upward development.
            Do choose a campsite uphill from valley floor.
            Do get away from exposed areas, pinnacles, peaks.
            Do get away from water.
            Do seek low ground in open valleys and meadows.
            Do move at once if hair or scalp feels tingly.
            Do not stand under trees.”[1]

Wilderness Survival trainer Peter Kummerfeldt amplifies Renner’s comment by adding the following:

            “Be proactive – don’t wait until you are getting wet to suspend outdoor activities.
Don’t be connected to the tallest object in the area.  If caught outside, move into low trees of even height and stand away from tree trunks.  Stay away from isolated trees.
Water is a great conductor of electricity – get out of the water at the first sign of a storm developing.”[2]  (For more information visit Kummerfeldt’s web site,

Thunderstorms have the potential to deliver large quantities of water.  Look for higher ground and stay out of stream beds that may flood significantly and without warning.
I monitor my GPS receiver’s barometer.  I change my elevation plot to a pressure plot and leave the receiver on.  Even though a GPS receiver may not be the most accurate it is the plot’s trend over time that I am concerned about.  Should I see the pressure drop noticeably I’ll take shelter or return to my vehicle.

The key is to stay alert and make a plan of action when a storm approaches. 
I previously posted a short article about using your GPS to monitor barometric pressure while in the backcountry; go here to read the post.  I thought it might be worthwhile to cover a few other topics about in the field observations.  This post is about thunderstorms.

[1] Jeff Renner, Northwest Mountain Weather, (The Mountaineers, 1992), p 100
[2] Peter Kummerfeldt, Surviving a Wilderness Emergency, (OutdoorSafe Press, 2006), p56-57 

Monday, November 9, 2015

Magnetic Compass Common Mistakes

The compass maker Brunton has listed the top 5 magnetic compass common mistakes when using a compass.
  1. Having the map 180 degrees incorrect when taking a bearing ie getting north and south mixed up.
  2. Using a compass near metal objects, or near electronic items, causing the magnetic needle to be inaccurate.
  3. Looking at the map all of the time and not looking at visual clues in the real world.
  4. Losing concentration and walking too far when you get to your point, falling victim to confirmation bias – the tendency to see things that confirm you are right, but miss things that show you are wrong.
  5. Only carrying one compass with you. If one breaks you are stuck.
Make sure you don't make one of the magnetic compass common mistakes.

Sunday, November 8, 2015

Contour Lines of a Topographic Map

Contours are the thin brown lines that snake across a topographic (topo) map.  Contour lines connect equal points of elevation such that every point on a specific line will be at that elevation above sea level. 


Contour lines are distinct and separate from lines for roads, coordinate systems (e.g., latitude and longitude) and trails.  Man made features like roads and buildings are black.  Contour lines are brown.  By adding elevation data to the map contour lines provide a three dimensional view of the terrain.  These lines provide shape and a sense of texture. 

The graphic above uses shading and electronic editing in an attempt to gain a three dimensional view of the terrain.  Compare the two maps.

Here are a few “keys to the kingdom” of reading these the brown contour lines.

There are two primary types of contour lines, index and intermediate lines. 

The dark brown, wider lines (below) are “index lines.”  The numbers adjacent correspond to altitude along the line.

For example, if the hiker locates his position on the topo and its right on top of the dark brown line with 5200 printed on the line, the altitude at that point is 5200 feet.  Consider the altitude to be the height above sea level.

The faint brown lines between the index lines are “intermediate contour” lines (see graphic above.)  Critical to intermediate lines is the specific elevation change between the lines.  This is known as the “contour interval.” The contour interval could be 10 feet, 20 feet or 200 feet; it just depends on the scale of the map and terrain.  To find the contour interval on a topo go to the bottom of the map or to the map key/index.  On a United States Geologic Survey (USGS) 7.5 minute topo map it will be at the bottom center of the map.  In the graphic below, the contour interval is circled in red.

In the small map above, look at Browns Mountain.  The spacing between the intermediate contour lines represents an elevation change of 20 feet.  Notice that the index lines are spaced five contour intervals apart or 100 feet between index lines.

Contour lines (index and intermediate) can provide a view of slope and pitch, depressions, ridge lines and level ground; the highs and lows of the earth’s surface.
The contour lines at Browns Mountain are close together and represent a steep increase in elevation.  Lines close together can indicate a peak, hill, ridge line or a cliff.

The contours of the land area to the left or west of Browns Mountain are spaced farther apart.  Such lines indicate flat ground like a meadow or plain.  Lines far apart make for gentle slopes and flat ground.

Ridges, valleys, and streams are represented by contour lines too.  A line’s shape identifies these land features.  For example, a valley’s shape is formed by a collection of “v’s.”  Tips of the v's point toward higher elevations.  Look at Alder Creek on the map below.  Note that the creek bed is in the bottom of a valley and water flow is from higher elevation to lower.

The contour lines that shape Alder Creek have v’s that point to higher altitude.  Look closely at the index lines and try to determine the elevation change as the creek flows north.

Contours shaped like a v or u, pointing toward lower elevation denotes ridges.  Notice the shape of the contour lines to the right and east of Alder Creek.  The v’s tips point toward lower elevation.  In fact, the v’s have become more like expanded “u’s.”

For more information about contour lines visit or search the internet for the “World of Teaching – Topographic maps” (a very fine power point presentation.)