Saturday, March 8, 2014

3/8/14 Report - Sand Movement and Obtacles, Speed Limit in 1861, Class Ring, Expensive US Coins.

Written by the TreasureGuide for the exclusive use of

Sand bar created by obstruction near shore.

I'm still having trouble uploading videos to blog posts.  I had one for today but ended up making a series of stills out of it to illustrate my point.

In this first picture the shore line runs left (north) to right (south), pretty much along the bottom of the photo,and the log sticks out from the shoreline in something like a 45 degree angle.  Most groins, which I talked about back a few posts, would stick out at about 90 degrees, of course,  Nonetheless the principles are basically the same.

In this illustration the waves have been hitting from the upper left corner in about the direction of the arrow.

The water was coming up onto the newly created sand bar that you see to the left of the log.

Notice the lack of sand to the right of the log.  That is what you would see happen as the result of long shore drift, which on the Treasure Coast is north to south.  Look at our inlets and jetties and you will see something very similar.

Picture two showing direction of water.

Picture two (above) shows the direction of the water as it comes onto and up over the sand bar.

In the upper left corner you see a wave about to hit the sand bar.

The sand bar builds as the water washes sand in from the upper left,  The waves crash in front of the sand bar, suspending sand and moving it up the slope.  As the water slows down as it goes over the bar, the water loses speed and drops the sand.

Some of the water that makes it over the bar runs to the right and back down along beside the log.  However, as both this water and the water running back down the front of the slope goes out, there is another wave coming in which crashes into the receding water, thus stopping it from receding unabated.  That creates a brief zone of no current where some items are dropped for the moment.

If the size of the waves do not increase as the tide goes out, everything will happen closer to the top of the picture farther out in the water and the bar will be extended out into the water.

Picture three showing how there is little sand on the right side of the log.
Of course the waves are coming in from the same direction on both sides of the log  (from the top left of the picture).  However you can see that on the right side of the log, there is no sand build up.

The sand to the right of the log keeps moving to the right along the shore with the direction of the waves that are hitting at an angle.   There is no sand moving in to replace the sand that is moving out on that side of the log.

When you find a situation like this, no matter if the obstacle is a groin or a log or rocks or whatever, the place to hunt is on the side where the sand has been depleted.  That is where items that might have been dropped over time and accumulated could be uncovered.

If the wind changes and the waves change direction (then coming from the upper right hand corner)
the process would be reversed, though not completely because of the angle of the log, and the sand would build on the right side of the log and be removed from the left side.  Then you would want to hunt the left side.

Due to our north to south running near shore currents on the Treasure Coast (the opposite of the Jet Stream by the way) the predominant direction is for beach sand to travel north to south.  So when you have a significant sustained reversal you might get a good opportunity to hunt the north side of obstructions.  Watch for those unusual opportunities.

When the wind and waves are hitting from the south, it has to be large and sustained to have a significant impact for a variety of reasons.  One the wave energy coming from the south is moving against the near shore currents and the sand pushed in the direction in the past has to be moved before you get down to productive levels.

Swimmers often like to hang out on sand bars, so when a sand bar moves, that is a good place to be.

Recent Find Found by Using
Knowledge of Moving
Sand Bars
If you know about how forces like these work and you know your different beaches, you can intelligently decide what places you want to check before you leave home.

Sand bars are obstacles to the flow of sand too, as are holes, rocks, etc. etc.

Get to know your beaches and how they respond to different conditions.

Today I started a new experiment to show how objects of different size and weight sink in sand.  It is not a very refined experiment but in the first ten minutes I was seeing interesting results.  I'll report on that some time when the experiment is done.

Did you know that you could receive a fine for speeding in St. Augustine in 1861?

City of St Augustine vs Lewis slave of B Olivero; Fast riding through the Streets - January
26, 1861 (St. Augustine City Court Record)
On this day appeared Bartolo Oliveros owner of said slave Lewis in answer to complaint made by City
Marshal against said slave for riding through the Streets of said City on the 20 inst at a faster gait
than permitted by the City Ordinance.

The said Bartolo Oliveros owner of said slave having admitted the guilt of his said slave. His honor
ordered a fine of five dollars to be entered against said Bartolo Oliveros owner of said slave and that
said slave stand committed until said fine and cost be paid.

Here is the source link.   It has numerous interesting tid bits on Florida history.

The President's new budget gives the US Mint  the authority to do research on the composition of coins and authority to change the composition of coins.

The latest figures available from the United States Mint indicate a cost of 1.83 cents to produce and distribute each cent and a cost of 9.41 cents for each nickel. All other denominations cost less than their respective face values to produce and distribute.

The cost of making and distributing 5 pennies is about the same as one nickel.

Here is the link.

We are having north winds and around a four or five foot surf this weekend.  It isn't enough to appreciably change detecting conditions on the Treasure Coast.  That is why I've been targeting modern finds lately.

Happy hunting,