COMPASS

The compass is an ultra-light, effective orientation tool. You can find both direction and location with a compass.

The compass needle points to the "Magnetic North Pole." The earth's magnetic north pole, however, is not located on the earth's "True Geometric North Pole." The magnetic north pole is in fact located SE of the true north pole, placing it in Canada. The difference between the two poles is called magnetic declination. Rounded to the nearest half degree, the magnetic declination for the Colorado Springs map as of 1999 is 11 degrees East. Magnetic declination actually moves west over time. The earth (or at least the crust we stand on!) spins to the east, while deeper spheres of magma and iron (the lithosphere) slowly rotates westward, pulling the earth's entire magnetosphere to the west. For the Pikes Peak region this approximate annual change in magnetic declination is 2 minutes 18 seconds West. Thus over 20 years time (year 2019) a total change of 46 minutes will occur. Since the declination is to the east and the change to the west, the change is subtracted from the declination. Thus in 2019 the magnetic declination will be nearer to 10 degrees East. Annual changes in declination can be much larger in other parts of the country.

Getting back to the compass. Magnetic declination on the Colorado Springs map must be accounted for as follows:
To convert Magnetic bearings to Map Grid bearings add 11 degrees.
To convert Map Grid bearings to Magnetic bearings subtract 11 degrees.
In order to correctly orient the map in the field do the following:
1. Place your compass on the center of the map compass diagram, lining up the fixed N-S line in the compass with Map North.
2. Rotate map & compass until the compass needle coincides with the diagrams Magnetic North Line.
Once the map is properly oriented, map and field bearings (azimuths) are one and the same. Field features may then be identified on the map by the common bearing. In short, the correctly oriented map becomes a model of the earth.
You can pinpoint your location on the map using a method called resection. First orient the map. Next find a feature (mountain peak, road intersection, etc.) that you can see and is on the map. Sketch a line (with a straight edge) or make a mental picture connecting the map feature to the same real world feature "out there." Repeat for a second feature. The point where the two lines cross is your location. A third line may improve the accuracy of your location.
If you know you are located somewhere along a linear map feature (a river or road) you can use "modified resection," which requires only one point. As described above, find a feature on the map and which you can see. Sketch a line connecting the two. The point where your sketched line intersects the original linear map feature is your location.