Written by the TreaureGuide for the exclusive use of the Treausre Beaches Report.
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Recent Mystery Find.
by Dave. |
These photos and the following email were just received from Dave.
Good afternoon, I recently started metal detecting and found this item on South Hutchinson Island Beach. It was about 18 to 20 inches deep. It was encrusted with barnacles and I knocked all that off. I was going to throw it away but thought maybe this might be something. I was told to reach out to you, that you possibly may know what this could be. Please let me know and if you have any questions.
Thanks
Dave
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| Another View of the Same Mystery Find. |
If anyone knows what this is, or just has an idea, let me know.
Thanks.
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You undoubtedly recognize this chart. I've used it more than any other. It is very important, but it is pretty complex and hard to read. I've attempted to explain it before, but just found this good explanation that might do a better job than I could do.
Below is that explanation from Mining the sea sand which is a good site that you might want to check out. It discusses a lot about beaches.
Reading the erosion and sedimentation graph
The behaviour of particles in water as researched by Heezen and Hollister (1964) has produced the most important diagram above.
It basically has a left-hand curve for sedimentation and a right-hand curve for erosion.
Horizontally it shows water velocity and vertically particle size but the scales are logarithmic.
The straight line in the middle gives a square root relationship meaning that a particle needs to be 100 times larger in diameter to sink 10 times faster, as is true for large particles.
A widening gap exists between the lefthand and the righthand curves, meaning that particles need higher water velocities to erode, but once dislodged, need a much lower water speed to settle out again.
The righthand curve for erosion bends forward for small particles like silt and clay, meaning that once these have settled, much higher currents are needed to dislodge them again.
As you can see, the lefthand curve for sedimentation, runs rather flat for small particles, following the law of Stokes where a 10 times larger particle sinks 100 times faster.
In between these two extremes the relationship is about linear such that a 10 times larger particle also sinks 10 times faster. Beach sand with its size of 0.2-0.5mm behaves like this. It is also located at the bump in the erosion curve where erosion is independent of water speed, which makes these particles eminently transportable.
We would have liked to see similar research done on wind speed and particle size, but to our knowledge this has never been done. |
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That is an important chart, that will help you a lot if you understand it, however it doesn't tell you how coins or rings or other targets would be affected by changes in water velocity. It also leaves out some other factors, but I don't have time to get into all of that right now.
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| Source: SurfGuru.com. |
So we had a higher surf on Thrusday but today it will be smaller again. The surf will remain small for about a week.
Good hunting,
TreasureGuide@comcast.net
