Basic knowledge of using a map and compass is necessary for anyone traveling on or off trail in Alaska. Not only does knowing how to use a map and compass help one from becoming turned around in the wilderness, it also helps the hiker to determine how far it is to certain points such as the nights' campsite.
This chapter will cover the basics of using a map and compass such as:
Triangulation (finding out where you are when you aren't sure)
Basic orienteering (knowing how to get to where you want to be)
The first thing to cover in the area of map and compass reading is to know some basics about the map and compass by themselves before trying to use them together.
Maps
Maps used in backpacking are generally topographical maps. These maps have markings to simulate the three-dimensional topography of the land. In other words, it is made to give you an accurate picture of what the land is really like such as where the mountains, rivers, lakes, streams, trails, swamps, glaciers, and roads are. The map uses many different types of symbols to represent different types of land.
Contour Lines
One of the most used symbols is the contour line. The contour line is usually colored brown and shows the "layout" of the land. Each contour line represents a certain number of feet above sea level. If you look at the numbers labeling the lines, you will notice that as the numbers increase, the land is getting higher above sea level, meaning that the slope of the land is going up. If the numbers are decreasing, the slope of the land is going down. In other words, if you were hiking in an area on the map where the numbers were going up, you would be traveling uphill. If you were hiking in an area on the map where the numbers were going down, you would be traveling downhill.
As you look at the contour lines, some of the lines are closer to each other than others. When the lines are close together, it means that the terrain is steep. When the lines are far apart, the land increases or decreases above sea level at a gentler slope. As you learn how to study a map, you will learn which course is the easiest to hike based on the distance apart the contour lines are.
The following land features are described by how they look on a map:
Moderate slope--contour lines are evenly spacedSteep slope--contour lines are closely spacedGentle slope--contour lines are widely spacedValleys--contour lines form a V shape pointing up the hill; these V's are always an indication of a drainage path that could also be a stream or riverRidges--contours form a V shape pointing down the hillSummits--contours form circlesDepressions--contours are circular with lines radiating to the center.Measuring Distances
When measuring distances on a map, one of the best ways to do it--especially in the field, is to use a piece of string. Make sure you know what part of an inch equals one mile and snake the string along the intended route. Then take the string and lay it on the scale at the bottom of the map to determine the estimated distance you will be traveling.
Declination
Basically, there are two "north's" to know and understand. One is "true" north. This north is the North Pole. The other north is called "magnetic" north. This north is where the needle on a compass points. These two norths' can make map and compass reading very confusing. So, let's try to make things simple.
First of all, true north is the north shown on a map. When you are looking at the map, it is always pointing up. It is also the place all of the longitude lines meet on the top of the world.
Magnetic north on the other hand is the north your compass needle points at. This point is actually just north of Hudson Bay in Canada.
Having two different "norths" makes it confusing because the north on the compass is not the same as the north on a map. This is a problem because in order to use the map and compass together, the "north's" have to be the same. Therefore, in order to use a map and compass together, you have to either change the north on the compass to the north on the map, or change the north on the map to the north on the compass.
Longitude and Latitude Lines
Longitude and latitude lines are used to find a point on a map or globe just like using the xy-axis is used to find a point on a graph. If you have ever used the xy-axis in math, then longitude and latitude lines should be pretty easy to learn. Think of the equator as your x-axis or 0 degrees latitude and the Prime Meridian as your y-axis or 0 degrees longitude.
The only thing to learn here is how to name the point you are looking at on a globe or map. If the point is right of the Prime Meridian, it is east longitude a certain number of degrees. If it is left of the Prime Meridian, it is west longitude a certain number of degrees. If the point is above the equator, it is north latitude a certain number of degrees. If it is below the equator, it is south latitude a certain number of degrees.
To locate a point on the xy-axis, you need both the x-coordinate and the y-coordinate. It is the same with finding a point on a map. You need both a longitude and a latitude to find a point and both are measured in degrees.
**Important: The largest degree you can have north or south is 90 degrees. The largest degree you can have east or west is 180 degrees.
If the point you are looking for on a globe or map is north of the equator and west of the Prime Meridian (which all points in Alaska are), then you would say that point is "x degrees west longitude and y degrees north latitude".
So, where do we find the degrees on a map in which to name our point? On the edges of the map, there are numbers for longitude and latitude lines. These are the degrees you will use to name the point you are looking at.
Compass
A compass is divided into 360 degrees of a circle going in a clockwise direction. Therefore, 90 degrees is east, 180 degrees is south, 270 degrees is west, and 0 or 360 degrees is north.
When using a compass for travel, do not follow the "floating arrow"; follow the "direction of travel" arrow.
When you are traveling a certain "bearing", it means you are moving a certain number of degrees in that direction. So if you were heading East, you would say your bearing is 90.
Using the Map and Compass Together
When reading about using a map and compass together, most books discuss a complicated issue called declination. Declination is the difference between true north and magnetic north. It is very important to understand what declination is all about and as you learn more advanced map and compass skills, you will undoubtedly learn more about declination.
In this chapter, I will teach you one of the ways of using a map and compass together without having to deal with declination.
In order to use a map and compass together, you begin by "orienting your map". Orienting your map means you are making sure the north on your map and the north on your compass are both pointing in the same direction. This is done by placing your map on a flat surface and turning it until the longitude lines (the ones that go up and down) are pointing in the same direction as your compass needle. By doing this, your map and compass are both pointing to magnetic north.
Now that this is done, let's try 2 examples you will run into when you are in the field:
Example 1
Let's say you know your location on the map and you know the point on the map where you want to travel. How do you get there using a map and compass? Here are the steps:
1. Orient your map with the compass
2. Lay the long edge of the compass base plate on the map, making a line from your starting point to your destination.
3. Holding the base plate steady, rotate the compass housing until the orienting arrow coincides with the north end of the magnetic needle (known as "boxing the arrow").
4. Read the bearing (in degrees) from the degree dial at the index line on the compass base plate and follow the "direction of travel" arrow keeping your arrow "boxed".
Example 2
This time let's pretend you are really lost and have no idea where you are. Using triangulation, you can find out where you are on the map, then you will be able to use the above steps for example one to get yourself where you want to be.
In order to use triangulation, you first of all must be able to locate at least two prominent points around you on the map.
There are several methods of finding your location on the map. I will go over two. The first is very easy and not quite as accurate as the second, but it is easier and quicker.
1. Orient your map
2. Look for some features around you such as a mountain, road, river, valley, lake, etc. that you can not only see, but also locate on the map in front of you.
3. Using a straightedge (compass base plate), place its edge right next to the landmark on the map.
4. Now align the straightedge so that it points exactly at the real landmark. Draw a line along the straightedge (the line will cross the symbol for the landmark on your map).
Here is the second more accurate method:
1. Orient your map and compass
2. Find the prominent landmarks around you and locate them on the map (preferably at least 90 degrees apart).
3. Hold your compass so the needle is "boxed" and turn your base plate so the "direction arrow" is pointing to the landmark you have chosen.
4. Take a compass bearing between you and the first landmark
5. Place the compass on the map so that one corner of the base plate rests on the landmark.
6. Keeping the corner of the base plate on the landmark, turn the entire compass on the map until the orienting arrow and the compass needle point to north on the map.
7. Draw a line on the map along the edge of the base plate from the landmark.
8. Repeat this procedure for the other landmark you are using on the map.
Where the two lines cross is your location. To be even more precise, do it a third time. If the lines do not all cross, you are somewhere in the small triangle the three lines create.
Remember, this section only briefly discussed map and compass reading. There is so much more in this area and a skilled hiker will learn more and more as his experience demands it.
