Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.
Yesterday I discussed liquefaction, which can occur on a beach under certain circumstances that cause sand to act much like a liquid. I showed a couple photos of liquefied sand being moved by big waves. Of course, most of the time that occurs near the front of the beach, but when the tides and swells are big, it can occur on the back of the beach.
Before delving more into the physical forces that move sand and other objects, this morning I thought it would be useful to mention the various beach zones of interest to the detectorist.
Starting off-shore in the shallow water, there can be a sand bar. That can be a good place to metal detect if there are a lot of bathers using the bar. That happens a lot down in the Fort Lauderdale/Miami area. It can be a very good place to detect for modern finds or what I call recent drops, but don't forget that the bar will move, and one side or the other, depending upon the direction the bar is moving, can be good detecting.
Inside of the bar, is often a dip, which can also be good detecting. In fact some of my best detecting ever was in a cleaned out dip. The dip can be full of sand and shells, but it can also be cleaned out down to bedrock, which of course is when the detecting can get very good.
On the beach front in the wet sand can also be good detecting, but it can also be poor, depending upon what is going on. This area can be good or poor, depending upon a variety of factors, especially whether the sand is building on the beach front of eroding. In either case, good water action can wash up good targets. In the wet sand below the berm you might be able to find the coin lines or coin holes that I've mentioned many times. They can also have other good targets beside coins.
The fourth zone is the dry sand area, which of course can be good if people have been using it. Hunting the dry sand is very different from hunting the wet sand or water because the water does not do as much sifting and sorting there. Detecting in the dry sand depends more on where things were dropped. In the wet sand things gets sifted and sorted more, so you are often looking more for where targets ended up rather than where they were lost. The water does however hit the wet sand area on some occasions and can definitely affect the distribution of finds.
The fifth zone is the dunes, where you will usually not be allowed to hunt. Very old items will typically be buried a foot or more in the dunes, but when the water hits the dune face, items can be washed out and onto the flat beach.
It can get a lot more complicated but those are some of the basics of the five zones.
---
We often talk of where you might find heavy items like gold. As I've said many times, it is really not the weight that we are concerned with. A ton of Styrofoam will float. It is more a matter of density, rather than weight. Other things are important too though, such as the shape of the object. Bend tons of steel into the shape of an ocean liner and it will float.
Here are the densities of some of the metals you might find. That helps explain why you can find aluminum when beach conditions are not very good, and why lead is a good sign if you are looking for beach gold.
Again, shape is also important. Shape a super tanker out of steel and it will float. Thin sheets present more surface area for the water to push around or lift.
Specific gravity is the density of an object relative to the density of a reference substance, usually water at a specific temperature and salinity.
Having a specific gravity of 19.32, gold is over 19 times more dense than reference water.
Again, shape is also important. Shape a super tanker out of steel and it will float. Thin sheets present more surface area for the water to push around or lift.
Specific gravity is the density of an object relative to the density of a reference substance, usually water at a specific temperature and salinity.
Having a specific gravity of 19.32, gold is over 19 times more dense than reference water.
Sand has a specific gravity of somewhere around 2.65 to 2.70. So being more dense than water it sinks in water. There are a variety of other forces at work on the beach sand though, and the shape and constitution of the sands makes a difference too.
Notice the specific gravity of aluminum is very close to that of sand, so it is no surprised that you can find it in sand that is building on the beach.
Another generality is that it will take a lot more water force to move gold than either sand or aluminum.
If you understand these things it will help you figure out how things are moving and that will give you a better idea of where they might be found.
One of the things about gold rings is the relative lack of a flat surface area for the force of water to act on. A copper coin on the other hand, will move differently than a gold ring not only because of the different density of the material but also because of the shape. Likewise the movement of a zinc coin will be determined in part by the adherence of materials to the surface of a corroded coin.
That will provide some background for future discussions.
---
As I said yesterday, the National Hurricane Center map is starting to light up. There is now a tropical storm :Edouard. Edouard will not affect us, but there is a new system down by South America to watch.
It is the time of year to start watching for storms.
Happy hunting,
TreasureGuide@comcast.net
Notice the specific gravity of aluminum is very close to that of sand, so it is no surprised that you can find it in sand that is building on the beach.
Another generality is that it will take a lot more water force to move gold than either sand or aluminum.
If you understand these things it will help you figure out how things are moving and that will give you a better idea of where they might be found.
One of the things about gold rings is the relative lack of a flat surface area for the force of water to act on. A copper coin on the other hand, will move differently than a gold ring not only because of the different density of the material but also because of the shape. Likewise the movement of a zinc coin will be determined in part by the adherence of materials to the surface of a corroded coin.
That will provide some background for future discussions.
---
As I said yesterday, the National Hurricane Center map is starting to light up. There is now a tropical storm :Edouard. Edouard will not affect us, but there is a new system down by South America to watch.
 |
| Source: nhc.noaa.gov |
Happy hunting,
TreasureGuide@comcast.net
