Define declination in map reading.

Define declination in map reading.

• A. The angular difference between magnetic north and grid north at a location.
• B. A measure of map scale.
• C. The angle of slope on the terrain.
• D. The angular difference between true north and magnetic north at a location.

Answer: (D)

Declination is the angular difference between true north (geographic north) and magnetic north at a specific location. This tells you how far the compass’s magnetic reading is offset from the map’s true-north reference, so you can adjust bearings to align your directions with the map. If declination is east, magnetic north lies to the east of true north, meaning you add the declination to a true bearing to get a magnetic bearing (and subtract to go back). If it’s west, you do the opposite. Declination varies by place and over time, which is why you check the current value for where you are. This concept isn’t about map scale or slope, and it’s not the difference between magnetic north and grid north—that other relationship describes a different navigation idea.

Declination is the angular difference between true north (geographic north) and magnetic north at a specific location. This tells you how far the compass’s magnetic reading is offset from the map’s true-north reference, so you can adjust bearings to align your directions with the map. If declination is east, magnetic north lies to the east of true north, meaning you add the declination to a true bearing to get a magnetic bearing (and subtract to go back). If it’s west, you do the opposite. Declination varies by place and over time, which is why you check the current value for where you are. This concept isn’t about map scale or slope, and it’s not the difference between magnetic north and grid north—that other relationship describes a different navigation idea.