Tuesday, May 10, 2011
5/10/11 Report - Back Dunes as Source of Cobs & Wax Seal
Wax Seal Found at Plate Fleet Beach.
This wax seal was eye-balled at the waterline near Corrigans. I'm now pretty sure that is what it is. You can see the right wing and part of the breast of a bird. It looks very much like the bird on the seal of New Mexico. Somebody said they would try to figure out who the seal belonged to if I could get a better photo, but that is the best photo I can get. The eagle appears to have both wings spread and head turned to the left as you view the photo. That's the best I can make out.
In an earlier post I mentioned the back dunes as being a source of shipwreck cobs and treasure coins. As you might know, you are not allowed on the dunes. And the sea oats that have been planted on many of the dunes are protected.
In my survey I listed the face of the back dunes and the toe of the back dunes as one of the zones. And as you might know, that zone was tied with the edge of the water for being the two most common places where cobs and treasure coins have been found. (Cobs and coins are not the same thing.)
I also mentioned that I have traced old shipwreck items from the back dunes. You might have wondered how that was done.
First, on some beaches such as Green Turtle Beach, the dunes are far back from the water and consist of small low mounds. At other beaches, there is a cliff at the back of the beach where the dunes have eroded away in the past, such as Wabasso or Turtle Trail.
At Green Turtle Beach where the dunes are way back and small, there is no way that old shipwreck treasure will fall out of the back dunes and end up on the beach in front. Those dunes are seldom eroded any how because they are so far back. They are also small and created by the wind. The only time they will erode is when the water washes over the dunes, as it does only on very rare occasions such as the 2004 hurricanes.
At other places where there is a significant cliff on the face of the dunes, the beach is narrower and the cliff relatively close to the water's edge. The sand behind the cliff has not been disturbed by Mother Nature for years and years and holds some very old items. How they got there is hard to tell. They could have been dropped near the surface a long time ago and been buried by the blowing sand over time. Maybe they were deposited there with the sand by large storms long ago. In any case they are there and have not been moved for a long time. It is also rather hard to get a fix on how deep in the sand those old items are.
You might ask how I know there are old items in the dunes at places like that. If you watch those dunes you will see when they do eroded. The water will generally undercut the bottom and the sand above will slide down the slope to the toe of the dune - sometimes in slabs.
When that happens you can detect the fresh slab and see what it holds. If you can tell where the slab came from then you will know the source of the objects.
There have been times when I detected slabs and other sand that came from the back dunes and found old objects and then detected the beach below that and found the same type of objects in basically the same condition. Since the fresh slabs have not been in the water, it is evident that the objects were coming from above rather than being deposited by the incoming water.
One example would be the dunes at one beach that is filled with small caliber bullets. I've found numbers of those bullets in the sand that came fresh from the dunes and also found the same type of spent bullets in the wet sand directly below the fresh slabs.
On beaches like that you'll also find light junk materials at the base of the dunes. The various levels of the eroded sand gets mixed together at the base, and some light junk will get washed up from the middle beach and deposited at the base of the cliff.
If you are there at the right time you can trace objects coming out of the dunes for yourself.
When you find objects coming out of the dunes, see if you can tell where the sand came from and then you might be able to determine the layer that those objects were in before they were eroded out of the dune.
Like I said, that is just one example.
It is a good practice when scanning a beach to try to determine if any old object is coming down from the back beach or being washed in by the water. Therefore, in addition to scanning south and north from the object, scan east and west from the object too. Scanning north and south (along the beach) might give you a clue to the existence of a coin line, and scanning east and west (perpendicular to the beach) might tell you if things are being washed in or out.
One scan pattern that I often use after finding something interesting is a spiral around the spot where I dug the object. That way you'll find any other objects in the same general area in any direction.
You can then repeat the spiral pattern on the nest object. (I also often use the spiral scan pattern in the water.) You might be able to see a distribution pattern.
That can be very helpful as I've explained in the past.
There is a new survey for you to answer in this blog. All votes are appreciated.
Treasure Coast Beach Forecast and Conditions.
The sea is calm today. The wind has been changing frequently lately. For a while it will come out of the south and then before long out of the west again. It hasn't been significant enough to affect much of anything anyhow.
Today and Wednesday the sea will remain very calm - good time to water hunt or hunt the low tide area. On Thursday the sea is predicted to be a little rougher. Nothing that will help beach conditions much, but it will probably make it tougher to get in the water or so far out at low tide.