5/20/17 Report - Why Nor'easters Move More Sand and Coins: A Small Scale Video Illustration.

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

Erosion I Found Yesterday

It is not often that I am able to capture such as good image of such a basic and important thing. Usually I don't have my camera, or the batteries or dead or for some other reason I just can't capture the image in a way that shows what I really want to show.

Yesterday when I was out I hunting, I saw the above little eroded cliff. I made a very short video that shows how water hitting the beach at a sharp angle slices away the sand.  That is something I often talk about, especially as it relates to Nor'easters.

This erosion is on a very small scale, but the small scale and the clarity of the water, worked out for the better.  The same thing you see in the video below happens on the beach on a much larger scale when the surf is larger.  I think you can see from that video how the water slices along the front of the cliff.

Here is the link to the video.  Take a look.  It is only nine seconds.

https://www.youtube.com/watch?v=I8aCk1zC0e4

Notice how the water speeds along the face of the cliff.

I suggest running the video and few times and watching how the water skirts long at the base of the cliff.

At the end, you see multiple steps in the sand.  The steps were created as the tide went down.  Some steps are greater than others because there were times when the waves were bigger.

Below is a an illustration of the eroded area and the neighboring beach. The general direction of the water adds sand in one place and removes it in another.  If the direction of the waves changed, the sand would be removed and added at different locations.

The curve in the beach is important.   To the right of the illustration, sand was accumulating.  It was only eroding where the water was hitting at an angle (orange line).

The water hits the cliff and bounces back off the cliff.  That water bouncing off the cliff then gets pushed along the face of the cliff by incoming water.  On the leading edge of the rushing water, you see a little swirl created where the wave pushes the water that is bouncing off the cliff.

I was glad I caught that on video.  I often see something I want to talk about, and for one reason or another, don't catch it on video.  On this small scale, it was pretty easy to see what was happening.

The movement of sand on the beach is multi-directional.  How the incoming and outgoing water interact is important.

When the water hits at a sharp angle, as in the video, there is a redirection of water as the outgoing water hits the incoming water.  When it is hitting at a sharp angle, there is not so much of a collision as when the water is washing directly up and down the slope.  When the water is hitting at a sharp angle, there is more of a combining and redirection rather than a collision that severely reduces the force of both the incoming and outgoing water.  In some areas it actually appeared that the two sources added together and added to the overall force.  There were times when the incoming and outgoing water combined to create a swirl that moved along the beach near the front of the combined sources.  The sand appeared to suspend more in the area of the swirl.

Clip From Another Video Segment

In the above illustration you can see the direction of the incoming water, the outgoing water and the area where they were gathering (arrows).  That area is where there appeared to be the most sand suspended, for the area at the base of the cliff when the water hit it with some force.  The swirl moved parallel to the beach for a short distance.

As I've discussed when I talked about trigger points and drop points, what is moved by the water is determined by the amount of force.  The small amount shown in this video moved sand but would not move coins - other than those that might happen to fall out of the bank.  If you understand the movement of sand and other objects on a beach you'll know better when and where to look for coins.

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This looks like it would be a good read.

The Wreckers: A Story of Killing Seas and Plundered Shipwrecks, from the 18th-Century to the Present Day Hardcover – July 14, 2005, by Bella Bathurst.

Unfortunately you don't get much of an online preview, but here is the link.

https://www.amazon.com/Wreckers-Killing-Plundered-Shipwrecks-18th-Century/dp/0618416773

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The most read post of April was the 4/27/17 Report - More On Cooper's Treasure Show. Salvage Lease Process In The Bahamas. Blog Provided Touch of Home to Deployed Detectorist.

People have been going back and reading a lot of the old posts.

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Happy hunting,
TreasureGuide@comcast.net

7/3/15 Report - How Nor'easters Produce Treasure And Why You Don't Get As Much Effect From Other Storms.

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

100 Plus Year Old Post Card.

Everybody knows that treasure is often found on the Treasure Coast after a good Nor'easter.  That has been observed and repeated for decades.  It is nothing new.  Just like everybody knows to look for erosion.  That is nothing new about that either.  But do you know why a Nor'easter is good for treasure hunting?  And why doesn't it work the same when the waves come from some other direction?

I'll put it together for you today.  I've never seen it explained like this before.

I've given you bits and pieces, but today I'll put together some of the most important key elements.

Why is it important?  Because it will help you know how it works and that will help you know when and where to look.

I've mentioned many times how the angle of waves are important.  Waves that hit the beach straight on do not generally create much if any erosion.

First of all waves hitting a beach directly at a ninety degree angle, wash up onto the beach and then back down the same path.  The backwash from one wave will be hit by another incoming wave.  At the place where they collide, much of the energy is lost.

If enough water is returning, just off the beach an undertow will be created as shown in the illustration below that I showed a few days ago.

On the East coast of Florida we have a north to south running long shore current as shown in the illustration below.  You can tell that if you watch how the sand has accumulated at places such as Cape Canaveral and on the north side of the inlets.

The illustration on the left shows how when the waves hit the beach straight on, the water goes up onto the beach, and then retreats back down the same path.




To the right is an illustration of the same beach with the same long shore currents running north to south, but in this illustration the waves are shown hitting at an angle coming from the Northeast. The waves come up onto the beach at an angle and then the water washes back down towards the water.

In this example, when the next wave hits the retreating water, instead of hitting it head on, it hits the retreating water an angle and pushes the retreating water southward.  A flow of water develops moving southward over part of the beach.

The net effect is that sand is moved southward along the beach and back into the off long shore current that keeps pushing it south.

I'm sure you've noticed when you have a Nor'easter and are seeing erosion as it happens, there is a north to south flow of water along the beach that moves the sand as well as other items north to south.  That flow will erode the sand and create a cut as the sand is washed away.

During times when the sand is eroding like that, I've thrown coins into the swiftly moving water on the beach and tracked the coins as they move southward with the water.

As that happens, water from the dunes is sliced away and washed south and down into the water.

So why don't the coins get washed into the water?

Sometimes they do.  When the velocity of the water is sufficient to keep them moving, they will be washed down and out.  But when the force of the water decreases to the "drop point," they'll be deposited where that occurs.

You might want to refer to my previous discussions on trigger and drop points.  That is terminology that I introduced.

So why don't waves hitting from the southeast do the same thing?

Waves hitting from the south or southeast can also at certain times create erosion, but that is less likely and usually not as much.  That is because when the back swash runs down the slope of the beach, it runs into the long shore current which is normally going the opposite direction

While I've seen littoral drift frequently talked about and illustrated in the literature recent years, I have never seen anything in the literature about how the movement of sand along a beach is different when the waves and off shore currents are going in opposite directions. You are getting that here today.

It would seem natural to me that when the northward moving water from the swells and waves reenter southward moving long shore current, you would get turbulence.  The south to north moving waves start out going against the natural flow of the off shore current, and then again when the water flows off he beach it again hits the south flowing current, so you don't get the synergism you would typically get with a Nor'easter.

That should advance your understanding of how a beach works and how and why Nor'easters more often produce good treasure hunting.

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Here is a book on theory of maritime archaeology.  You can get a good bit of it through the free preview.  Click here for the preview.

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We have at least a few more days of one foot surf along the Treasure Coast.

Happy hunting,
TreasureGuide@comcast.net