How many of you have heard of a treasure hunter finding a sign that tells them to go a certain degree line on their compass and off they go out a hundred yards and find a piece of buried metal or other object? When this happens my Bunk-O-Meter goes off and I have to start asking questions and you should too!
Magnetic declination is the angle between magnetic and true north. This angle changes over time and what was 33 degrees on a compass a hunred and fifty years ago won't be 33 degrees today. This is why I have to question the how a treasure hunter can use a sign that gives them a certain degree line to follow and low and behold they come across another clue. The correct degree line to follow in todays time will be several degrees different than what was originally put down and you will need to calculate the new line to follow.
This is where the links on our blog can come in handy. There are a few things that you will need to get the correct degree line. The gps coordinates of the site you are working and a good idea of when your treasure site was layed out are the two most important. Research is the key on getting an idea of when the treasure cache was hidden. On a site we were recently working we found a couple of objects that helped us date it to the 1890's. By having the correct decade to figure magnetic declination we can be sure to have accurate degree lines to follow. As a test to see how important it is to have an accurate line to follow try picking out an objects a hundred yards off and walk at an angle 4 degrees different on the compass from your oblect and see how far you are away from it once you reach the end of your hundred yard walk.
Now for the part where the links on the blog help out. http://www.ngdc.noaa.gov/geomag/declination.shtml
By using this website you should be able to work those degree lines correctly and hopefully become treasure finders instead of treasure hunters. Good Luck and Good Hunting!