Orienting a Topographic Map

A map is oriented when it is made to correspond to the ground it represents. Remember, on a topographic map, north is the top of the map.

There are four ways to orient a map:

I. BY COMPASS

With a protractor, draw a magnetic north line anywhere on your map. The declination diagram in the margin of the map will give you the direction and size of the angle between grid north and magnetic north.

Diagram I - Orienting a map using a compass

Do not use the margin diagram itself as the angles are often exaggerated by the cartographer so that the numerical values for the angle can be inserted.

Place the compass on the magnetic north line and turn the map and compass together slowly until the needle points to magnetic north on the map.

II. BY DISTANT OBJECTS

If you know your position on the map and can identify the position of some distant object, turn the map so that it corresponds with the ground.

Diagram II - Orienting a map by an object

III. BY WATCH AND SUN -(in the Northern Hemisphere)

If Daylight Saving Time is in effect (in summer), first set your watch back to Standard Time. Place the watch flat with the hour hand pointing toward the sun. True South is midway between the hour hand and XII. True North is directly opposite. Note, this method is very approximate.

Diagram III - Orienting by a watch and the sun

IV. BY THE STARS

In latitudes below 60° North, the bearing of Polaris is never more than 2° from True North.

Diagram IV - Orienting by the stars
These constellations revolve counter-clockwise around the Pole.