Saturday, November 15, 2014

11/15/14 Report - $587,000 Charles-Joanna Mexican 8-Reales, Beach Dynamics, Coins Washing Up On Beach

Written by the TreasureGuide for the exclusive use of

Source of photo:

This is the 8 reales that brought in over $587,000 in the recently completed Sedwick Coins Treasure Auction 16.

Maybe you'll be the one to find the fourth.


Back close to twenty years ago (I can't believe it has been so long.) Jensen beach was eroded back into the Seagrape trees by the walk-overs at the back of the beach.  Since then sand has been dumped on that beach many times.

Back when we had the hurricanes in 2004 (I think that was the year.) John Brooks was eroded back all of the way to the walk-over.  That kind of erosion doesn't happen very often.

There are periods of years when a beach will continue to erode and wear away.  And then there are periods of accretion.

When a beach gets eroded way back, you will often see a different kind of sand.  When Jensen was eroded way back, there was a course brown sand.  That, of course, has since been covered by fine white sand.

You should pay attention to the different types of sand because it can tell you if old layers are being uncovered.

The same thing goes for Turtle Trail.  Recent renourishment projects covered the beach with a fine white sand.  It is being lost, but by the time the old sand starts to emerge they will probably dump more sand to cover it up.

Here is a simple sketch of a beach cross section.  The blue line represents the water line.

Simple Beach Cross Section Illustration.
This is a wide low beach such as the one at John Brooks.  A different type of beach would be the beach at Turtle Trail that is more narrow and has a high cliff at the back.

In this diagram, let's say A (black line) is the old beach.   Then B (reddish line) represents the beach after very big erosion occurred.

Then the beach refills, up to the thin green line (C). 

Back in 2004, for example, John Brooks eroded a lot, taking the sand down to a low level, something like B above.  Then it refilled.  Since that time it eroded and refilled time and time again more near the front portion of the beach.  Cobs were found in layers of sand well above where the level of sand had been eroded in the past and way too far to the front of the beach to have come from the dunes.

Old coins will be washed out of the dunes and down onto the beach and even into the water at times.  That occurs more often on narrow beaches with high dunes behind.

I have no doubt that most of the shipwreck coins found on John Brooks in recent years were washed up onto the beach from the water since they were found in areas that were previously eroded much lower and too far from the dunes and too high to have come from the dunes.


On the Treasure Coast the surf will be a little higher on Sunday, something like 3 or 4 feet.  Out about a week an 8 foot surf is predicted.  The long range predictions often don't work out though.  We'll have to wait and see.

Happy hunting,