Written by the TreasureGuide for the Exclusive use of the Treasure Beaches Report.
If you look at the illustration from that document, which I posted at the top of this page, you'll see some interesting things. It goes along very well with my recent series. The illustration shows some important things about sand movement, but also the history and evolution of the barrier island along the Treasure Coast.
First, you'll notice the direction of the long-shore current and littoral drift. The net effect is pushing sand southward along the coastline. You can see that in many features such as the sand that piles up on the north side of inlet and how the beach starves south of inlets that have the flow of sand cut off by jetties, etc. The littoral drift to the south accounts in part for the average greater erosion from north'easters, which go in the direction of that predominant flow, and the net building, or accretion, effect from south winds and currents. It will help you to understand the flow of sand on a beach.
The illustration also shows how the islands were shaped, as well as the westward movement. Notice for example the "relict" inlets, which are inlets that once existed but are no longer open. And the overwash lobes where high surf once pushed sand over the island and into the lagoon, extending the island to the west. When someone like Mexia in the 17th century describes an inlet, don't confuse the inlets position as being the same as it is today. You probably know that there were other inlets along the Treasure Coast in the past, and inlets move over time (when not aided by jetties or whatever, they migrate south), and the modern inlets are not where they once were. For example, the inlet near Fort Pierce was north of the current inlet, which was opened in more modern times. You should think about what that says about where you are likely to find centuries old coins.
For example, if there was an old inlet at the site, the area was washed out and you wouldn't expect sand from bygone centuries to be in place. You would not find old sand in-place in an area, except for very deep layers.
Here is another illustration from the same Florida Anthropologist article.
It will help you learn how to "read a barrier island." Not just a beach.
Sorry, but the figure had the first letter of each line cut off. I think you can read it anyway. It is important to realize that barrier islands are among the most dynamic of landforms. Significant changes can happen in years or decades so you have to take that into account when interpreting historical descriptions.
I've told before about seeing after one of your major storms how close blind creek was to being opened by the erosion.
The purpose of the article is not to document that evolution of the barrier island. The purpose was the examine historical resources such as those by Mexia, Dickenson and Brahms and from their descriptions find out where the major Ais settlement was located.
The article is well worth reading if you are interested in the historical documents related to those early explorations or the location of the native American settlements during early contact periods.
The article is not easy ready and the browser is not user friendly, but if you are interested, it is worth the effort.
For several reasons it is good to know how the barrier island evolved. It is a great illustration of how sand moves, and therefore has important implications for where old coins might be found.
Here is the link.
There is a lot of good information and a lot of hints in that article if you take the time to study it.
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| Surf Chart for the Fort Pierce Jetty Area from SurfGuru.com. |
Looks like a nice high surf on Saturday and Sunday.
The high tides are still high too.
Good hunting,
TreasureGuide@comcast.net