Finding Places to Metal Detect – In Depth – How to Overlay Maps

This article is something I have wanted to do for a long time but wasn’t sure how to go about it. I knew it would be difficult and before even I started typing here I have about four hours in getting all the pictures together and figuring out exactly how I want to do it to make sure it’s easy to understand. I don’t know how well this will work but follow along and I think by the end you should have enough understanding to do it on your own.

This is my method. There are other methods out there but this one works best for me and what I’ve stuck with for years. One of the advantages of this is once I get my initial scale set and I have the maps lined up, when I move to overlay another part of the map, the scale stays the same or only needs minimal adjustment. When I get in my groove I can usually overlay an entire township (over a 100 sites that are no longer standing) in about an hour.

Tools you will need

First you will need to download google earth. It is free and will only take a few minutes. With google earth you can add placemarks of the sites and it will give you the coordinates. You can also put notes on your placemark for future reference. I will add property owners information there (if I can find it) and any information I have on the site.

Next you will need the older map you want to use to overlay. You can purchase maps from www.historicmapworks.com and I have heard of people using them with the watermarks on the map without purchasing them, I can neither confirm nor deny my personal involvement in such an endeavor. The local library should have these maps as well. I have received permission in the past from libraries to photograph these old maps for my personal use. Another resource for some later maps that are good for overlaying is www.lib.utexas.edu/maps/. I am sure there are others out there you can use if you search for them.

The last thing you will need is some kind of pointer that you can hold on your screen to mark locations. In all the years I have been doing this I have never come up with a perfect solution. If anyone has a one please contact me!

Before we get started

So you have google earth and your old map and you’re ready to get started. I always try to start on the edge of a town so I can easily figure out where I’m at in reference to both my old map and google earth. If there is not a town then look for creek crossings, sharp bends in roads, any distinct pattern that will help you to quickly find it on google earth. I always try to at least get three reference points I can line up with to get my scale correct on google earth. I prefer to use intersections but sometimes this just isn’t possible so I will use houses that are still standing but I wouldn’t use a creek or river because I rarely find where they match up correctly.

This example is pretty close to perfect in a few ways. I have three intersections I can use for reference and everything lines up perfect. This will not always be the case! Sometimes you have to do a lot of educated guessing, you might have to use houses from the old map that are still around today as reference points. Sometimes you can also use fence lines (property boundaries) as references as well, you will often find they haven’t changed. Another thing you will run across is where roads are gone or they have moved and it can sometimes take a little longer to get all your reference points lined up to ensure you are overlaying correctly. If enough people like this article I will do more on how to overlay in heavily wooded areas (where you can’t see the roads on google earth as reference points) and how to overlay some of the tougher maps where roads have changed, hard to find reference points etc.

Let’s get started

The first thing you need to do is pull up your historic map on your screen. Once this is accomplished now pull up google earth. Now click your google earth icon that will be at the bottom of your computer so we are back on the historic map. Make a mental note (the best you can) the general size of the map. Click your google earth icon again bringing it up and try to size it quickly to the size you think is close to the historic map, also moving google earth to roughly where you think the historic map reference you’re starting with is located. Click your google earth icon again to minimize it now take some kind of pointer and hold it on your first reference point on the old map. Once you have that hold it steady and click your google earth icon again to bring it up, now move your google earth map so that reference point is lined up. Click google icon again now place your pointer on the second reference point you’re going to use. Again, click your google earth icon to bring it up, now you can see what adjustments you need to make to google earth so those two points line up. You might have to zoom in or out, just keep playing with it and repeating the steps until you have them lined up perfectly. Repeat these steps for your third reference point until you have it perfect or as close to perfect as possible

(Above) I pull up the old map and use a pointer to hold my first reference point- I then click my google earth icon to pull up google earth

(Below) Once google earth is up I adjust it so 1st intersection lines up with my pointer

(Above) I go to my second reference point on the historic map and repeat. Again, I click the google earth icon to bring it up

(Below) Once google earth is up I see how far off I am and keep playing with zoom on google earth until both references line up

(Above) Now that reference points 1&2 are lined up we verify that number 3 lines up, we just repeat previous steps

(Below) in this case reference point 3 lined up perfect, sometimes you have to make small adjustments.

(Above) I will click my google earth Icon multiple times bouncing between maps until I find a spot to mark

(below) I will use my pointer to mark the spot until I can mark it with google earth using a placemark

(ABOVE) In this 2 miles x 1 mile strip of land I was able to quickly find 4 sites that are just farm field now with no visible signs of ever being there. Google earth automatically calls any site you mark on the map “untitled placemark” once I have looked up the current owner I will use their last name instead and I will make notes on the property, contact info. And anything else relevant that I might need.

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When you are overlaying, to match the historic map you have to be zoomed out so far that you can’t always tell if there is a house still standing, especially when you are in wooded areas. It’s also nice to mark some of the older houses so you have places to door knock when the fields are planted. This is a really good example of how amazing some of the map makers were. Again, we are looking at two miles wide and 1 mile tall. I couldn’t see these places I marked to know if there was even anything there (except where the house on the corner is that old map said school) and yet when I zoomed in look at how close I am! You upload any of the coordinates for the 4 sites that there is no visible sign left of them and I guarantee you will walk right to them! Not all maps are this great but for a first example I didn’t want to make it difficult.

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