4/25/18 Report - Understanding Factors Involved With How Coins Move in Sand. Archaeological Detecting. Emeralds and Silver Bars.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.

A couple days ago I talked about how coins move on the beach.  Evidently a lot of people were interested in the topic and followed up by visiting previous posts on the subject.  As a result I decided to show something that clearly illustrates some of the main factors involved.  It isn't simple because it depends upon a variety of factors - the force and direction of the water being a couple of the most important.  The complication is that the water force can change from near zero to very high.

First, here is a question for you?  Will a coin always move in the same direction as the current.

Here is an illustration.

The illustration shows a coin lying on a sand slope.  The current is moving towards shore and up over the slope very much like it would with a surge.

What do you think will happen?   It depends upon the how strongly the current is moving, but if the current is very slight it can move sand in and pile it up on the slope and eventually cover the object.
However, if there is enough current, but not too much, the current will move the sand from around the coin, especially the that part of the coin that faces the current.  That would be red area shown in the next illustration.

When a sufficient amount of sand is moved from that area, the coin will slip down the slope a notch and remain there until enough sand is moved for the same thing to happen again.  Of course the current would have to remain about the same and the coin would be in the same orientation on the sandy slope.

I've seen this actually demonstrated in a tank filled with water and sand and a controlled current.  This is a case in which the object moves opposite the direction of the current,  If the current is either too weak or too strong, it won't happen the same way.  If the current is strong enough, it can push the coin along in the same direction as the sand.

The important factors are the characteristics of the objects to be moved, including both the density and shape, as well as the force of the current.

When an object like this coin is on a slope and the supporting sand is removed, gravity moves it down the slope.

One of the important characteristics of a coin is the shape.  Coins tend to lie flat against the surface and present a small and rounded edge towards any modest current.  The current then speeds a little as it is forced around the stationary object.

A variety of things can destroy this entire scenario.  Just think of a wave crashing right on top of the slope and coin.  In that case, sand will be thrown around and the coin moved rather abruptly.

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The Society of American Archaeology web site lists a variety of projects involving detectorists.

Here is the link.

http://www.saa.org/ForthePublic/Resources/MetalDetectingInArchaeology/MetalDetectoristsParticipatinginArchaeologyRe/tabid/1030/Default.aspx

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There are several 1715 Fleet emeralds up for auction in the current Sedwick auction.  They have starting bids of around $100.  I've posted about people who have found emeralds on the Treasure Coast beaches.  Some of those emeralds are not the greatest, but one exceptional one was a 68 karat emerald found by a lady that was collecting shells at Golden Sands beach.  Watch for green in the shell piles.

https://auction.sedwickcoins.com/Crude-natural-emerald-from-the-1715-Fleet-8-5-carats_i29836856

The big silver bars seem to be bringing in really good prices.  I think one is up to about $29,000 already.

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The surf is pretty small now and won't start increasing again until Monday.

Happy hunting,
TreasureGuide@comcast.net