Written by the TreasureGuide for the exclusive use of the Treasure Beaches Report.
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| What do you see in this photo? Dead Brown Leaf? |
I was watching Gold Rush: Parker's Trail last night and they took some samples to see if a plot of land might have enough gold to be worth working. They didn't show the sampling process very well, but it looked like the sample came from a very small area. After obtaining the results, there was a discussion, during which it was mentioned that larger samples are more accurate. That might be so, but it depends upon how the sample was taken. A larger sample might not be any more accurate than a small sample if the sample wasn't a representative sample.
A representative sample is a sample that somewhat accurately reflects the relevant properties of the whole from which the sample was taken. In this case they wanted to get an idea about how much gold they would get if they mined the entire plot of ground. From the sample, they would generalize about the plot.How was the sampling done? Was it a good sample? Was it a representative sample? Did the results of the of the sample accurately reflect how much gold would be obtained from the entire plot? A sample does not always result in good conclusions.
Is the gold bearing dirt distributed evenly around the plot or is it just found in some areas or at some depths? For a sample to be helpful, it must be done correctly. If you sample one spot and the gold is distributed unevenly (for example it might be found in one area but not on much of the land or it might be found at a certain depth), you could easily get very misleading results. There are well-established principles for effective sampling, but that goes well beyond the scope of this post.
As I recently said, things (including treasure) tends to cluser. You could have a small densely packed area and either hit or miss that area when you take your sample. That would affect the representativeness of the sample and the sample could easily be misleading.
To apply sampling more directly to beach metal detecting, let's say you want to know if it is worth spending much time detecting a particular beach. You might be able to identify some areas that you are seem more interesting. Maybe you can tell that some areas look more promising. For example, if you just check the dry sand, there is a good chance that you will miss a good coin line or coin hole in the wet sand area.
I recommend sampling. I believe sampling is a good idea. You always do it, because you can not cover the entire beach, but good sampling is done thoughtfully and systematically. Taking a good, or representative sample, involves more than doing a little detecting, and the conclusions you can draw from a sample, depends upon how well you sample.
Another thing to consider when sampling a metal detecting area, is a single item can be worth more than a hundred or even thousand other finds. A valuable ring for example, can be worth much more than a bunch of normal coins. The possibility of very scarce but very valuable items, makes sampling more difficult than sampling for numerous small pieces of treasure of similar value. In that case, one piece, or data point, will not dramatically skew your results like a single scarce but very valuable item might.
Of course, over time, as you continue to metal detect an area over weeks, months or years, you will gain a greater understanding of the area and more accurately define your area of interest.
Now I'll throw in a few more difficulties. Beaches change. especially in the wet sand area. There might be changes that are difficult to predict or recognize. And the dry sand changes too. There are busy days, and not so busy. There are busy areas, and areas that do not have as much traffic. And there are other detectorists that might hit an area before you.
Changes can be seasonal, or event related. They can be weather related or caused by variations in human activity. Conclusions drawn from a sample taken on a particular day, might not be valid in a year, or on another day.
My main point is that sampling can be helpful, but it must be done well, and you must be careful about your generalizations or conclusions.
Here is another post on the topic of sampling for metal detecting.
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On the same TV show, possibly another episode, they were testing two sluices with different kinds of riffles and wanted to see which type of riffle did a better job of catching gold. They used lead shot rather than gold. Instead of just throwing the shot in, they first smashed it with a hammer. Why? As someone said on the show said, they did that because gold is not round.
One of the things I discussed in a previous post is that the shape of an object will have an effect on how that object will move on a beach when exposed to the flow or force of water. They recognized the effect of the objects shape when they did that test. I'm not sure if lead shot provided an accurate measure of how the riffles would work with gold, since gold is more dense than lead with a ratio of roughly 19 to 11. That seems to me to be a big difference, but they were satisfied with using lead. They probably have a better feel for that than I.
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Did you see that dead brown leaf just below center of the photo shown at the top of the post?
Here is a closer look.
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| Looks Like Dead Leaf, But It Is Actually a Ruddy Daggerwind Butterfly. |
Here is a view when it is opening its wings a little.
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| Ruddy Daggerwing Butterfly. |
Good camouflage, isn't it?
There is a lot of interesting nature to see when you are out metal detecting.
Things are not always what they seem to be.
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Did you see on the news where a young manatee started playing with boogie board that a child was riding near the Fort Pierce inlet?
I remember a diving detectorist down in South Florida telling how he was metal detecting on the bottom and a big shadow went over him. He looked up and it was a manatee.
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I'm surprised that there has been so little tropical activity on the NHC map so far this year, but the peak of the hurricane season has not yet arrived.
Still nothing of much interest. Just a little bigger surf (only maybe three feet) predicted for mid-week.
Good hunting,
TreasureGuide@comcast.net