Tuesday, June 30, 2015

6/30/15 Report - Sea Groins: A Hint For Low Erosion Times. Space Debris. Degaussing. Ivory Finds.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.

High Carat Gold Ring Groin Find.

Yesterday I mentioned a couple things from an excellent study that looked at erosion of Florida's beaches beginning with 1883 and ending 2011.  I thought I'd take the time today to emphasize and elaborate on one small part of that study.  Here it is.

Dewall and Richter (1977) reported that seasonal beach changes are on the order of two to three times the magnitude of the yearly trend at Jupiter, Boca Raton, and Hollywood beaches at Florida’s SE coast. The storm surge during Hurricane Ivan 2004 was 2.5 m with significant wave heights greater than 12 m at Panama City beaches, Florida west coast. This event caused a landward migration of 16 m, and the shoreline recovered 10 m in a 20-d period following the storm (Robertson, Keqi, and Whitman, 2007).

To put that another way, the seasonal changes that occur to those beaches are two to three times larger than the changes that normally occur at the same beaches from one year to another.  It can look like there is a lot of erosion, but much of it will be seasonal or temporary and reversed in short order.

The example of Panama City shows that a hurricane can cause as much as 16 meters of erosion, but in this case, it only took twenty days to reverse more than half (10 m) of that erosion.

They also mention that there will be even larger variations in the shoreline where there are obstacles to the natural flow of sand, such as inlets, groins, etc.

There is a good hint that you might catch if you think about it.  When beach conditions are poor, there is always a chance of catching some small but beneficial erosion near an obstructions even at times when you will find very little or no erosion elsewhere.  Between obstructions such as groins, the sand will pile up in one corner and then when the waves change direction, pile up in the other corner.  You can take advantage of areas like that and work areas like that when no other areas are eroding.  That can be especially effective in areas where there are a lot of people and therefore a a good number of recent drops.  The increased movement in sand may be smaller than you would like to see but still be enough to make it possible to find items that were lost slightly longer ago than you could find if there were no movement of sand.  Instead of uncovering old items, this smaller and more frequent movement of sand can uncover items that were buried just weeks or even days ago.

I spent a lot of time working old sea groins in the past.  A lot of good finds, including the unmarked 22K gold ring shown above, came from working between sea groins and other structures.  Other obstructions to the flow of sand work about the same as groins.

Here is the link to the study that I was talking about.


And here is the link to the site providing the groin illustration.



An unmanned SpaceX Falcon 9 rocket bound for the International Space Station exploded a couple of minutes after liftoff Sunday morning. It was the third cargo mission to the space station to be lost in recent months.

I heard on the TV they were telling people not to pick up any debris from that if they saw it.  Seems are space program is not what it once was.  We've talked a good bit about space debris being found on beaches in the past and even how to test titanium.

Here is the link to the story about the recent rocket failure.



Talking about the news, last week I kept hearing the word "degaussing" in relation to the IRS erasing the subpoenaed emails of Lois Lerner.  I don't know how Hillary erased or destroyed hers.

Anyhow, degaussing is a word that is very relevant to both nautical history and computer history.

Here is what wikipedia says about degaussing.    Degaussing is the process of decreasing or eliminating a remnant magnetic field. It is named after the gauss, a unit of magnetism, which in turn was named after Carl Friedrich Gauss.  Due to magnetic hysteresis, it is generally not possible to reduce a magnetic field completely to zero, so degaussing typically induces a very small "known" field referred to as bias. Degaussing was originally applied to reduce ships' magnetic signatures during the Second World War.  Degaussing is also used to reduce magnetic fields in CRT monitors and to destroy data held on magnetic data storage.

Here is how it was done in World War II - again according to wikipedia.

The term was first used by then Commander Charles F. Goodeve,RCNVR, during World War II, while trying to counter the German magnetic mines that were playing havoc with the British fleet. The mines detected the increase in magnetic field when the steel in a ship concentrated the Earth's magnetic field over it. Admiralty scientists, including Goodeve, developed a number of systems to induce a small "N-pole up" field into the ship to offset this effect, meaning that the net field was the same as background...

The original method of degaussing was to install electromagnetic coils into the ships, known simply as coiling. In addition to being able to bias the ship continually, coiling also allowed the bias field to be reversed in the southern hemisphere, where the mines were set to detect "S-pole down" fields. British ships, notably cruisers and battleships were well protected by about 1943.

My dad worked on a minesweeper in WW II, but it had a wood hull.

At one time in the early days of personal computing much of the data was stored on tapes that were very much like the audio tapes used on tape decks.  Tapes and also computer discs were erased using degaussers.

Here is a vintage deguasser purchased from Radio Shack with original box.  I would guess that would be a collectible now.

Vintage Magnetic Tape Eraser

Original Box.
I was in on a lot of computing history.  As far as I know I  actually wrote the first computer program to announce "You've got mail."  Actually it said "You have pnotes."  At that time we called email pnotes, which stood for "personal notes," which were exchanged between individuals.  Before that you had to go see if you had new emails.  The program that I wrote watched for new incoming emails and announced their arrival.  Forums were called gnotes, which stood for "group notes."  We worked on international mainframe networks before the internet.  Just an aside on one of those things I did in an anonymous way.


If you find any ivory, such as the ivory higa that I once showed, you should be aware that they are very strict about selling ivory.  Here is something about that from a recent KovelsKomments.

A ton of elephant ivory was crushed in New York City’s Times Square on June 19, 2015. The U.S. Fish and Wildlife Service co-hosted the event with other conservation groups. Carvings, tusks, jewelry and more were sent into a rock crushing machine to be turned into dust. Much of the ivory came from the shop of an antiques dealer, who was sentenced to 30 months in jail and fined $150,000 for selling poached ivory. Other ivory crushes were held in Denver in 2013, and China this past May. Ivory laws have been passed in many states, but there is concern about antique ivory works of art caught up in the new laws. The law that makes it illegal to import new ivory was passed in 1989. Now some states’ rules confuse or stop sales of things like pianos with ivory keys, vintage ivory jewelry and figurines, even mahjong tiles. Art and antiques dealers want existing laws to apply only to ivory from elephants killed since 1989 so ivory works of art can be saved and displayed in museums.


I have a lot of new stuff in mind to post.  I won't start that now though.  

I'm so tired of reporting no change in beach detecting conditions, but that is what it is.

Happy hunting,