Written by the TreasureGuide for the exclusive use of the Treasure Beaches Report.
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| Surf Chart from SurfGuru.com. |
Looks like tomorrow we'll be seeing a bigger surf.
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I've been putting this off for a while, but I'll give it a shot today. One factor that I haven't talked about much yet in my How Coins Move on a Beach series, is the tides. I'll try to not run on about it too long.
Some of the greatest water force exerted on a beach is at the point of a crashing big wave. I've shown pictures before of how the vertical force of the wave digs into the sand as shown below.
At the point of the crash material is suspended, which is the first step in material being moved, whether it is sand, rocks or coins. As long as objects are covered or settled into the sand, they won't be moved.
I showed the wave tank picture shown below before too. It shows the same thing but very realistically. You can see the same thing going on that is illustrated in the photo above, but you can also see in this picture the disturbed sand moving backwards to build a little hill or bar. Some of the sand can be seen suspended in the water too.
So, what does that have to do with the tides? Well, as the tides come in or go out, the area where the waves break changes. That area moves up the beach and then retreats and repeats with each tidal cycle.
But obviously something isn't shown here or the sand would be continually stripped from the beach. There are also times when there is a net accumulation of sand on the beach. That happens when the sea is not as rough and the swash is greater than the backwash. The swash pushes sand onto the beach.
During calmer seas you will see the beach build and during rougher seas you will often see it erode. The point to remember is that during calmer seas coins are not moving as much as the sand. It requires more force to move coins than sand, and the coins tend to get buried when the beach is building. When the sand is getting stripped, the coins can get moved too, but they still generally move less than the sand so you sometimes see coins uncovered on the beach.
When the tides are low, the waves are breaking in front of the beach or low on the beach, and when the tides are high, they are breaking higher on the beach. When the tides are high and the sea is rough the waves can be breaking high on the beach and dig into the dunes. At that point, you might see objects fall out of the dunes.
Objects that are moved relatively easily such as zinc pennies aren't far behind the sand. Some coins like the little aluminum coins of some of the Caribbean countries can be found right in with the sand that is being churned by the crashing waves.
I seldom detect right in the crashing waves because it is challenging and your equipment might break, but I have done it a few times in the Caribbean. I found the small aluminum coins washing around with the sand right in the breaking waves. That surprised me the first time.
There are times when you find a shell pile composed a big heavy shells and you'll find a few coins, even quarters, in with the shells. There are times when rocks and things get thrown up, but that requires, first that the rocks and coins be exposed, and second, a good amount of force. Not too long ago I posted that engineering article from the early twentieth century that talked about the very heavy objects were moved by very large waves.
I really like to see a big high tide combined with big waves, which is what we had back in 2020 and 2022 when some very old coins got eroded out of the high back dunes.
So the thing about the tides is how the crash zone moves up and down the beach with each tide cycle. One complicating factor is the changing wind and surf conditions within and between tide cycles.
Another complicating factor is, once the coins get dragged down into the surf and buried, often between rocks or reefs or whatever, they will be staying there barring some extreme or unusual circumstances. Maybe salvagers will use blowers to move the sand and lift the objects, at which point they become more vulnerable to natural forces, but normally when the salvagers are working, the seas will be calm.and coins will generally be covered again before long.
That area right in front of the beach, especially when there is a rock or solid bottom, when the sand and shells get cleaned out can make for some excellent detecting. I've told about times like that before. It doesn't happen often, but tons of coins and jewelry can be found when the dip in front of the beach gets cleaned out. Below is a link to a post on one of those.
Picture loose material in the crash zone getting suspended and moved and then picture the crash zone moving with the tide cycles, first up the beach and back down repeatedly. The suspended material will mostly be moved down the slope, but some material will be pushed forward by the swash.
Well, I think that is it for now. I'll call that Part IX of the How Coins Move on a Beach.
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I've acknowledged that AI is a great research tool for any detectorist or treasure hunter. I've also pointed out some shortcomings and concerns. For one thing, AI is not always correct. And there are other things that I'm concerned about.
I don't know what values any system has. Every chatbot has values of some sort embedded in it - intentionally or not. Honesty MIGHT be one. Cooperativeness might be one. Those are just a couple of examples. But an AI system acts on the basis of some type of values, but you don't know exactly what they are. It can be influenced in some way too. There are coders. There is a training process, whether it is built in or externally influenced. We need to be concerned about the values that are built in or influencing such capable and pervasive systems. Values are at the heart of the matter. What is the system built to accomplish and how can it be influenced? To whatever extent it becomes autonomous, you have to wonder, if it trustworthy? Is it correct? Is it honest? Exactly what can it do? What can it gain control over? What can go wrong?
When used for metal detecting, there isn't a huge amount of danger. If built into a metal detector, there is not much to be concerned about. I'm just saying that it can be helpful, but on a larger scale, we need to be informed.
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Watch for the
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