Monday, December 27, 2010

12/27 Report - Beach Erosion Illustration

Cut South of Fort Pierce Inlet This Morning.

I showed this cut a few days ago. The cut has been going up and down every few days.

Just a few days ago the cut was about six feet deep. Today the cut was only about three feet deep.

There is about three feet of new mushy sand over the previous harder surface, so most of the coins here are now down a few feet and out of detector range.

When I arrived this morning, a guy asked what I was looking for. I hadn't turned my detector on yet, and I told him I was looking for coins. He said there is nothing here, and explained this was all fill sand and I wouldn't find anything there. I thanked him for the information and continued to check out the beach.

I don't know if he really thought there was nothing there and was really trying to help me or if he was just trying to discourage me from detecting there. In either case, don't put too much stock in what strangers tell you. Some may not know what they are talking about, and some will see you as competition and try to deceive you.

The primary reason I wanted to show this beach today is that it provides a very good illustration.

A beach next to an obstacle like a inlet or jetty will be cut off from the natural flow of sand from the north and will therefore erode easily.

While watching this beach erode a few days ago when it was really getting beat up, I noticed that the water coming in along the jetty gets deflected off of the jetty and towards the south. The maximum force of the waves was funneled towards the south focused on a point near the center of the cut.

Illustrated Beach Similar to The One Shown in the Photo Above.

In my diagram the circle labeled "A" is a point near where the waves would hit with near maximum size and force. On the real beach that is what was happening and a coin hole deveoped near that point.

You'll seldom if ever see a really good cut that is not curved. The big cuts are usually created by water that comes in and slices along the front of the bank like shown by the lines at the right of the diagram labeled "B." That slices the sand at the bottom of the bank and washes it down the slope.

That would be very different from waves that go directly up the slope, hit the bank, and then recede directly down the slope in the same path. That is illustrated by in my diagram by the lines labeled "C".

Waves that directly hit the beach at a ninety degree angle, generally build the beach rather than erode, as do waves hitting from the southeast, which tend to push sand back up onto the beach as usually happens in the summer.

I started another topic a few days ago, I'll get back to it some time soon.

I was really surprised by how many people checked into this blog over the holidays. It seems my readers are really devoted.

On eBay there is a listing for a small vial of cochineal recovered from the 1715 Cabin Wreck Site in 1992. That is the first time that I've noticed cochineal from the 1715 Fleet offered for sale on eBay.

The seller tells about the cochineal and a bit about how he recovered it. You might want to read the listing.

I had a little trouble with the blog editor today. I kept losing text. It seems a bit messed up.

I got word that there was a good cut and coin hole down at Jensen Beach a day or two ago.

It looks like today some of the old cuts have filled in, but it also looks like there are still some interesting spots out there.

I picked up an old nickel on a beach that is very heavily over-detected today. Something good must have happened to bring that coin within range. That is always a good sign to watch an area like that for future development.

It is cold out there, especially in the morning.

The seas are only going to be four feet or less for a couple of days, so don't expect much to happen in that time period.

Like I said, there are some interesting spots out there, although in my opinion the overall condition of the Treasure Coast treasure beaches is not good for finding cobs.

There are still some decent coin holes filled with modern coins to be hunted.

Happy hunting,