Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.
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| Sand Moving In Surf After Esaias. |
Before Isaias, I had been looking at several academic articles on liquefaction. I'm sure you now know that liquefaction causes sand and soil to act very much like a liquid. I won't get into the causes of that again now.
I also showed amazing photos of big waves, mostly by Clark Little, in which you could see sand being picked up into waves that were breaking on the beach.
Perception is not as passive as you might think. Perception involves some level of processing and interpretation of the raw sensory input. If you are familiar with a term, such as liquefaction, you will be more ready to see it in the world. Sensory input is organized and interpreted by reference to information provided by the central nervous system.
Having seen what appeared to be examples of liquefaction in photos of big waves, when Esaias stirred up the water, I decided to see if I could see what I will now call sand flows (sand appearing to move much like a liquid). We did not get the huge waves breaking on the beach like those so beautifully captured by the photography of Scott Little, but I did catch some sand flows.
You can see the brown water near the center and especially left of center in the photo above. And in the photo below you can see the sand and small items piling up where the back flow hits the incoming water.
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| Sand and Bit of Shell and Things Washing Around. |
Of course we all knew that things get washed around by the surf. That is not anything new, but I believe we now have a better understanding of one way a lot of sand can be moved when the conditions are right.
Below is one of Clark Little's photographs showing sand being picked up into a wave. It appears that the surface of the sand is being rolled up into the wave. I think the photo shows perhaps a little fisheye effect, but it still looks to me as if the surface layer of sand is flowing as a mass.
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| Sand Being Picked Up By A Wave. Source: ClarkLittlePhotography.com |
As you know from my previous discussions on trigger points and how different items are moved by water, it takes more water force to suspend some items and keep them moving. As I've often repeated, it isn't entirely by weight.. The density of the object and the shape of the object have something to do how much force it takes to move various items. I've conducted my own simple experiments that verify that.
In both of my photos the movement of sand and pebbles or whatever is mostly vertical. In the Clark Little photograph, which involves a bigger wave and more force, the movement of sand is also vertical. I talked in the past about seeing items thrown up onto the top of a cliff, and that is one way it could happen.
The layer of sand in the photo looks very homogenous. I might be able to find a Clark Little photo showing a less homogenous surface. If I could find a less homogenous surface, perhaps with rocks or something, you might be able to see the separation of various types of material occurring. However, it could be that a lot of separation and sorting has already occurred, and that is why the surface appears to be so homogenous. That is probably the case, which means it might be difficult to find anything else but homogenous surfaces in similar situations.
As much as I'd like to, I can't think of a way simple way to measure the lifting force in such a wave. I did however get a new waterproof video camera that might help. I'll see if I can get some good views to show me areas in rough water where I haven't been able to see before.
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Esaias turned out to be not a very big deal, but 2020 started out with some pretty good beach detecting. You might remember that February and March produced several days of good old Spanish shipwreck finds on the Treasure Coast.
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Gold was up this morning to something like $2045 per oz. And silver was up too. Some are predicting as much as $2200 per oz. for gold.
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I just learned that one of my Treasure Coast beach fossil finds is worth in the neighborhood of $350. I distinctly remember finding it, but didn't know that it would be worth anything like that much.
I was walking along with my metal detector and saw it about fifteen yards away all by itself. There were no shells or anything except sand and that one fossil, which was kind of unusual.
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Not much of interest in the tropics right now, and the surf remains small. Expect the same for at least a few days.
Happy hunting,
TrreasureGuide@comcast.net