Written by the TreasureGuide for the exclusive uses of treasurebeachesreport.blogspot.com.
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| Source: nhc.noaa.gov |
There are two tropical storms now: Nano and Omar, but that isn't all.
Nana and Omar are both headed away from us in opposite directions, but there are two more waves coming off of Africa. I expect continually high tropical activity for a few weeks, but have no idea if we will be hit by anything big. We'll just have to keep watching the Atlantic to see how things develop.
I don't expect anything big for the next few days. In fact smooth surf is predicted for the rest of the week.
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In the past I've compared treasure hunting to tracking big game. A lot of people put a lot of emphasis on the metal detector they use. Of course you want to have a good metal detector, but like with hunting, it is just as important to know the habits of the game and how it moves. As I've said before, if I was depending upon someone for food, I'd trust the wiley Indian with a bow and arrow over the city slicker with the best gun ever made. You have to find it before you can shoot it.
Beach treasure is very much like big game. It moves. It moves according to certain principles. And it helps to know how it moves so you can be where it is most likely to be.
Everybody knows that there are signs to look for. They know that treasure, especially old treasure, is more likely to show up when and where there is erosion. They know it shows up on some beaches more than others. They know to look for dips and older layers of sand. They know to look for other signs, such as ballast or musket balls. But many of the hidden movements of treasure are not well known, and there have been some long-standing myths.
Most of the time you do not see how treasure moves. It is hidden by sand and water. You only see or detect it when it shows up or is near the surface.
It does move according to certain principles though. It moves according to the principles of physics, and those principles are being more fully understood and described by scientists. I just discovered one research paper that gives many of the relevant details. The title translated from Dutch is Simple General Formulae for Sand Trasnport in Rivers, Estuaries and Coastal Waters. It was not written to cover the movement of objects such as coins, but covers many of the relevant physical principles, so you just have to apply them.
The paper is not easy reading an involves a lot of advanced mathematics. I'll give you a few of the easy to understand excerpts and add a few comments of my own. Here is one illustrative paragraph.
In coastal waters the sediment transport processes are strongly affected by the high-frequency waves introducing oscillatory motions acting on the particles. The high-frequency (short) waves generally act as sediment stirring agents; the sediments are then transported by the mean current. Field experience over a long period of time in the coastal zone has led to the notion that storm waves cause sediments to move offshore while fair-weather waves and swell return the sediments shorewards. During conditions with low non-breaking waves, onshore-directed transport processes related to wave-asymmetry and wave-induced streaming are dominant, usually resulting in accretion processes in the beach zone. During high-energy conditions with breaking waves (storm cycles), the beach and dune zone of the coast are attacked severely by the incoming waves, usually resulting in erosion processes.
That paragraph tells us very little that we didn't already know, but it does support what is generally known and believed by many treasure hunters. Generally, it is saying that waves stir up sand and then the current moves the sand away, and stormy seas tend to move sand out to sea while calmer seas moves sand onto the beach. So for the reader of this blog, there is nothing new or unexpected about that. I've said that all before, and you probably noticed it for yourself.
But this paper gets more detailed and adds a lot, including, among other things, a precise mathematical language for describing the movement of sand and the beach.
Here is another paragraph.
Sand transport is herein defined as the transport of particles with sizes in the range of 0.05 to 2 mm as found in the bed of rivers, estuaries and coastal waters. The two main modes of sand transport are bed-load transport and suspended load transport. The bed-load transport is defined to consist of gliding, rolling and saltating particles in close contact with the bed and is dominated by flow-induced drag forces and by gravity forces acting on the particles. The suspended load transport is the irregular motion of the particles through the water column induced by turbulence-induced drag forces on the particles. Detailed information is presented by Van Rijn (1993). The definition of bed-load transport is not universally agreed upon. Sheet flow transport at high bed-shear stresses may be considered as a type of bed-load transport, but it may also be seen as suspended load transport. Some regard bed-load transport as occurring in the region where concentrations are so high that grain-grain interactions are important, and grains are not supported purely by fluid forces. The suspended load transport can be determined by depth-integration of the product of sand concentration and fluid velocity from the top of the bed-load layer to the water surface. Herein, the net (averaged over the wave period) total sediment transport in coastal waters is defined as the vectorial sum of net the bed load (qb) and net suspended load (qs) transport rates: qtot = qb + qs. For practical reasons the suspended transport in coastal waters will be subdivided into current-related and waverelated transport components.
So there is movement of suspended sand and also movement of sand along the top of the beach, which the paper treasts as different types of processes: the one being grains only in contact with water, or suspended, and the other type of movement involving grains in contact with other grains. The way they describe the motion of sand particles on the surface of the beach reminds me very much of the way I described the five ways that coins move. The movement of grains along the bed is described as gliding, rolling and saltating.
I won't get into all the details now, but a day or two ago I talked about the "net" effect of various object movements. The effect of the movement of treasure that we are interested in is similarly a net effect. On each wave, an object that is being moved can move in different, and very possibly opposite directions, so what we are interested in is the "net" movement.
I barely got started on this, and it gets pretty detailed, but I wanted to recommend this paper to you because it does provide a lot of very useful information, which applies not only to grains of sand, but also to other types of objects that may be on the beach, including coins.
You can easily translate many of the principles to treasure, but you have to take into account other variables such as density and shape. In this paper grains are treated as homogenous. Treasure coins have a different density than sand, but the many of the same principles still apply. In fact all of the basic principles apply if you take into account the different densities and shapes of the treasure objects
Here is the link. https://www.leovanrijn-sediment.com/papers/Formulaesandtransport.pdf
That paper is heavy reading, so be prepared.
In addition to that paper, the most useful information for understanding beach dynamics and the movement of sand and treasure is the Heezen and Hollister chart below. I've discussed the application of that chart several times in the past so won't comment on it again now.
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| Heezen and Hollister chart. |
You can get some of the basics of the Heezen and Hollister chart by using the following link.
https://treasurebeachesreport.blogspot.com/2020/02/22620-report-reading-water-to-find.html
That information is key for understanding the movement of treasure objects on a beach.
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If this is real, I need it.
https://www.youtube.com/watch?v=ZHk13Xa8dqI
Really cool.
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Did you hear about the 77 NFL players who tested positive for COVID? They thought they needed to be retested and were. None of the 77 had the virus.
False positives could certainly explain a lot of the asymptomatic infections. You won't be symptomatic if you didn't really have the virus.
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Happy hunting,
Treasureguide@comcast.net