Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.
One of the interesting odd items in the Sedwick auction yesterday is the lead coin shown above. As you can see, it was listed as lot 1201.
You don't often see lead coins, but that Nicaragua 10 peson coin is one that has an interesting history.
… fascinating relic from the rebellion of 1927-33 that pitted forces under revolutionary leader Augusto Cesar Sandino against the U.S. military, Sandino eventually being assassinated but still revered today as a national hero and symbol of resistance to U.S. domination in Central America. Tokens like this one were exchanged for goods from local merchants.
If you dug up a lead coin you might think it is some kind of token, weight or fake.
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I've been thinking of doing this post for over a month now, but it isn't an easy one and I still don't have it together. The topic is very complex and involves a number of factors and interrelationships, but I'll do my best to make it clear, which means keeping it simple to some extent.
I previously did a number of posts on the movement of sand and other objects. Different objects move differently depending upon a variety of factors, and an object such as a coin can move in a variety of ways.
The main reason we are interested in the movement of sand is that it can cover or uncover the the types of objects we look for. The uncovering can occur naturally, which is necessary for the beach detectorist, but if you are working a salvage lease you can move the sand using blowers.
What I want to describe today is the relative movement of sand and other objects. First I must repeat one thing that is often neglected - it is not just about weight. The density of the object - not it's weight - is important, but it's shape is also important. A flat thin piece of copper will be washed around by the water differently than a coin of the same weight. You'll frequently find small thin pieces of copper washed up and laying on or near the surface of the sand when you can find little else. And an oval lead sinker will move around very differently than a flat or triangular one.
To get the basics, I'd recommend studying the following table shown above and a previous post in which I explained it.
Here is that link.
So a certain amount of force is required to move the sand and a certain amount of force is required to move an object such as a coin. The amount of force required to move sand will typically be less than that required to move the coin. Therefore, sometimes the sand will move, but not the coin. The sand might then uncover the coin or let it sink down to the surface vacated by the sand.
In a previous post I mentioned five ways that coins move, so that can get complicated, however coins and items such as coins will move less often and not quickly as sand. So the thing that is important is relative movement.
Imagine the situation in which the beach sand moves but the coin remains relatively stationary. The coin will be uncovered and if the sand continues to move without the coin moving much, the coin will sink down to the new lower surface of the sand where it can stay until it is covered again. That is not an unusual scenario. One important thing to remember is that the coin will remain basically stationary as long as it remains covered. If there is enough force the coin can move when the sand moves, but in most cases it won't move as much as the sand.
If you sketched a Christmas tree and took the side on one side, that would be a fairly typical coin movement pattern over the years. Every time there is erosion it might drop with the sand surface and drift a little towards the surf. It might get covered from time to time but seldom get washed back up. Usually it would stay at its current position until it is uncovered again.
A ring, because of its shape, will get washed up less often than a coin because of its shape. There is less surface area for the force of the water to act on. Once either of them reaches a deep level they will seldom be washed up. It would take a rare event for that to happen. And once either reaches shelter in a rock crevice, it would be extremely rare for either to be washed up.
Where a lot of the action happens is where the wave breaks. That produces a lot of turbulence and lifts sand, rocks and other things that can then be pushed up the slope by rushing water. Again, it will take a lot to wash a ring up the slope because the lack of flat surface area.
What makes things especially complicated is the continually changing force of the water as it comes in and goes up the slope and then descends back down the slope and all of the interactions. It would be much easier to figure out if the water simply flowed in a continuous stream, but that is far from what we are dealing with.
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The Sedwick auction concluded today. The last session included a variety of less expensive lots, including some rather large groups of coins, clumps, paper money and mounted coins. Among the items were the following group of miscellaneous religious items.
Here is the lot description.
Lot of twelve crosses and religious medallions and other items in base metals, various periods (1600s-1900s). 47.95 grams total, 1/2" to 2". Cool little collection of objects, from a three-masted ship to a functioning miniature spur to various medallions and simple crosses to two crosses (one ornate though incomplete) with inlaid cabochon emeralds. Great for further study.
Some of the lots in the final session went unsold, but I thought the auction did much better than I expected. For the most part, bidders were not deterred by the economic downturn.
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It looks like we will have a two or three foot surf for a couple of days and then a possible increase.
Happy hunting,
TreasureGuide@comcast.net