11/10/25 Report - Best Dissertation on Beach Stranded Shipwrecks and Continuation of Series on How Coins Move. Record Cold Front.

 

Written by the TreasureGuide for the exclusive use of the Treasure Beaches Report.

It has been a while since I posted Part IV, but today I'll post Part V of my How Coins Nove on a Beach series. We are close to getting down to the nitty gritty.  I'll start out by posting the above illustration once again.  It shows how when a wave breaks on the beach it "scours away at the beach material."

Here is video clip of a YouTube video of the same thing happening in a wave tank.

You can see two things I've talked about.  First you can see the dip in the sand where the wave breaks.  You can also see suspended sand that getting pushed to the left.

Here is the link to the video.  It shows how that develops.

When the depth of the water is less than half the wavelength, the wave starts to lurch forward and break. Sand (and other things) in front of the break can get pushed forward while other sand is pushed back to form a sand bar. The greatest force is exerted where the wave crashes, which suspends sand ( and other things when there is enough force) that can then be easily moved one way or the other.  Below half the depth of the wavelength the bottom isn't affected by the wave but can be affected by other than currents such as the longshore drift.

Now I'm going to discuss the related findings presented by a dissertation on the archaeology of shore-stranded shipwrecks. It looks at a lot of old shipwrecks.

Below is a map showing the shoreline surveyed.  It is in South America and the predominant longshore drift is south to north - the opposite of the Treasure Coast, but the principles are the same.

The erosion areas of the more directly face the waves coming from the south quadrant.  The erosion areas are indicated by the red circles labeled E.  You might also be able to see the red rectangles along the beach in the areas of erosion.  Stable areas are somewhat protected from the waves coming from the south.

Remember, when sand is building at one location, it is coming from somewhere, and when it is eroding, it is going somewhere.  Both sides of the equation are important.

Of course, it works the same way on the Treasure Coast.  You'll see a cut in one location and then go around the bend where you'll see no cut or even accretion.  Angles are important.

This illustration if from the dissertation and shows what I've been talking about.  It is a general long-term perspective.

The breakers tell you where the reefs or sand bars are located because those shallow spots cause the waves to break.  Then the breakers stir up (or suspend) sand and other objects, which can then be moved in one direction or another.  Remember that items in deeper water or protected by layers of sand won't be moved, until the sand over it is moved.

Here is another illustration from the dissertation.  This one shows the typical summer and winter beach profiles.

The Summer profile shows how the gentler summer waves pushes sand up to create a berm and higher beach whereas the higher energy winter conditions pulls sand down to create a dip and sand bar.

If you've been reading my blog, not much of this will be new to you, but the dissertation examined actual shipwreck remains that appeared on the beach in winter and were uncovered and disappeared in summer.

Here is another illustration from the dissertation showing the relatively stable position of two theoretical wrecks that are covered and uncovered in different seasons. Ship A is uncovered on the beach in the winter and B is uncovered in the water in the winter.

People often seem to think that newly uncovered items, whether shipwreck timbers or a coin, just washed up, but often it was there all along and just got uncovered.

Below is one of the sections of a wreck studied in this dissertation.

And below is a plot showing two originally connected sections, where the separated parts were located when surveyed in 2002 and 2013.

On the left is shown how the frames were probably originally attached. In the center is the position of the two section as surveyed in 2002, and on the right their position in 2013. Note that in 2013, one or both of the frame sections were moved so that they were then closer together.

How they moved was determined both by the nature of the items and their original location and their exposure to the water force (just like coins or other things).  Of course, you'd expect those closer to the water to be exposed to more force and movement (all other things being equal).

The same principles apply to coins.  They are uncovered and moved according to the same principles.  They have different characteristics, but the same principles apply.  

The dissertation is over 160 pages, and you might want to at least browse the rest of it.

Here is the link.

setting in North Carolina (Queen Anne’s Revenge site), observed that wrecks in these (17) The Archaeology of Shore Stranded Shipwrecks of Southern Brazil (Torres, 2015).

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Surf Chart from SurfGuru.com.

So, we'll be having a cold front come through, which will produce one day of bigger surf.

The temperatures are predicted to drop into the 30s or 40s, so bundle up.

Incidentally, the common stock of Odyssey Marine that I mentioned at the end of last week just happened to be up over 12% since I mentioned it.  10% in a day isn't a bad investment, but that was one day and not a recommendation for the future.

Good hunting,

Treasureguide@comcast.net