Written by the TreausureGuide for the exclusive use of the Treasure Beaches Report.
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| Two Images From The Sebastian Inlet Cam Taken Minutes Apart a Couple Days Ago. Submitted by JamminJack. |
As you can easily see, the weather changed. Jack sent a third photo, which showed the beach under a more sunny sky once again.
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I mentioned that I dug the bottom of an aluminum can buried maybe 18 inches deep the last time I went metal detecting. As I said, I intended to discuss that and will try to do that now.
It is often said that deeper items are old. And people talk as if heavy items sink. So how did a thin aluminum can bottom get so deep? It doesn't often happen and it can be a sign to move on, but the dynamics are fairly complex.
First of all, as I've said in the past, how much an item weighs doesn't determine how deep an item will be buried in beach sand. It would be much more accurate to talk about density than weight, and there are still other factors. As I've said on several occasions, a ton of Styrofoam will float, as will a steel ocean liner. The shape of an item will have a lot to do with how deep it will be found in the sand.
I also don't like to talk about such items "sinking" in sand. Try it yourself. Get a bucket of sand. Lay a gold ring on the sand, and if the sand isn't exposed to some other disturbing force, the ring will not sink into the sand. It will remain on the surface unless you in some way disturb the sand by applying some type of additional force.
Besides water movement, other forces on a beach can move the sand and other items. The wind is one. I've talked about all that before, but the point I am making here is that the sand must be disturbed for items be more deeply covered in sand. I think it is more accurate to describe the process as relative displacement rather than sinking. It is not caused by gravity pulling the object through the sand.
For an item to sink (if I use that word even though it seems to me misleading) in sand, the sand must be moved in one way or another. The thing we most consider is erosion. As the sand is moved by the force of water, the sand is moved more than many other items, leaving the more moveable items to settle into the space vacated by the moving sand. A coin or sinker can move horizontally like the sand, but those objects will tend to move less rapidly and less distance horizontally than sand.
If you take a block of Styrofoam and put a heavy object on it or somehow hold it in place while beach sand builds on top of it, once it is covered by an amount of sand that will not immediately be washed away, it will continue to get covered by more sand until the sand starts to erode again. It will become more deeply buried - but not sink in the sand. That can actually happen, but is very rare. Seaweed, a rock, or other things can hold the Styrofoam in place long enough for it to get buried.
Of course the shape of the object also will have an effect on objects, but I won't get into all that again right now.
The thing I wanted to describe is how an item like the bottom of aluminum can could end up buried relatively deep in the sand.
Like other objects, the aluminum can bottom found a lower level when the sand was relatively low. In this case, down 18 inches from the surface of the beach where I found it. At some point some sand and water got on the aluminum bottom enough to hold it in place. Once even a very thin layer of sand on the beach surface and the object is remains covered, it will tend to remain stationary. It won't be moved as long as the sand is stationary or slowing accreting, but once the sand starts eroding the item can be quickly swept away when the sand surrounding it is removed.
Once an item is covered it will remain put until the sand around it is moved. When the sand around the object is moved, the object can move to a lower level, but it will largely remain in place until the encasing sand is disturbed. (I won't get into how items such as coins are thrown up on to a beach now. That happens too, but much less frequently.)
I've discussed angles, flows and a variety of factors in more detail in the past.
The main point is that once an object like the aluminum can bottom becomes covered by even a thin layer of sand it will remain in place and continue to get more deeply covered as the beach builds.
Objects can more properly be said to sink but that is not the predominant case. For example, objects can sink during liquefaction, but that is much less frequent case, and is confined to more limited times and spaces.
When you find deep items that are less dense, such as aluminum, it will provide the detectorist with good information. If one object like that is deep, others will be also. Deep aluminum will normally be a sign that good objects will not be present in the same area.
It can happen that dense items will be found in layers of sand above less dense objects, but that is normally not the case and I won't bother to describe how it happens now.
The important thing, is to use dense and not so dense objects and where they are found as good information that can tell you where to spend your time. That is a big reason I do not like to use much discrimination. Instead of trying to pick good objects out among junk, I'd rather move to a location where good objects are being clustered. There are exceptions, of course. Much is said of reading beaches, but people seldom include an analysis of depth and target distribution patterns. If you can interpret distribution patterns vertically as well as horizontally, you will have a good idea of where to look and where not to waste your time.
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That is a difficult topic because there is no established terminology. I've tried before to come up with a term that describe the rate of movement of different types of targets relative to beach sand, but don't have any good simple terms. The rate of movement of objects relative to the movement of the beach sand is influenced mostly by density and the shape of the object as well as the type of sand and the amount of water force. There are so many factors and interactions that it is not an easy topic to discuss.
The key to understanding all of this in my opinion is the diagram given in the following linked post.
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The current Sedwick auction will be held November 3 to 5. Not much time left.
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| Source: MagicSeaWeed.com. |
We had a northeast swell but not a huge surf combined with a small tide.
The surf is generally getting bigger than it has been for most of the summer.
Happy hunting
TreasureGuide@comcast.net