Saturday, November 27, 2010
11/27 Report - Vertical Concentration, Cobs, Erosion and Bottle Hunting
Van Antwerp's Pharmacy Bottle.
This one is on sale on eBay, but the reason I'm talking about it is that it is the same type of bottle that got me started in bottle hunting - a Van Antwerp's Pharmacy Bottle from Mobile Alabama.
I was hunting down south of Miami just after hurricane Andrew when I noticed some old bottles floating in the surf. I never hunted for bottles before, but I recognized that the bottles I saw looked old, so I found an old plastic bag and started picking up the bottles. I remember that day very well.
I later sold that bottle, and for a higher price than this one is listed for. The market for old bottles has dropped significantly in the past few years. EBay and other online auction and retail sites have made many old bottles easy to find and collect, and as a result, prices have dropped. That is the case for unremarkable bottles. Prices for rare or exceptional bottles remains high.
Of course, you con't find rare or exceptional bottles very often,but you can often find bottles that help pay a little for gas money.
My main point is one that I often make: Be alert to various kinds of treasure. If you are a coin shooter, study and keep your eyes open for other types of treasure. The more things you know about, the more consistently successful you will be.
We often talk about coins showing up on a beach. How cobs get to where they are eventually found is not a very simple matter.
When conditions are good, you can often find more than one cob at a time. And they are often found very near the surface. As I've mentioned several times, I can't remember hardly ever having to dig very deep to retrieve a cob, and I have eye-balled them more than once, obviously meaning that they weren't covered by any sand at all.
Most detectorists recognize that conditions for finding cobs are often "good" when there are big cuts on the beach.
Part of what happens when the beach is cut is what I call vertical concentration. Vertical concentration occurs when cobs from various layers and depths of sand end up laying on the same level or surface.
Let's say that there are four cobs in the sand on the beach. (Right now I'm not going to discuss how they got there.) The cobs are buried at various levels. Let's say one is at six inches, one at ten inches, one at twenty inches and one at twenty five.
When the beach begins to cut, the sand washes away and the cobs are left behind. Cobs, being relatively flat and heavy, are not washed down the slope and into the water as quickly as the sand because their flat surface keeps them from sinking into the sand. At the same time, the edge of a flat cob does not present much surface area for the receding waves to push against.
As a result you'll have cobs from various layers of sand on or near the surface of the sand at the base of the cut. Only one of the coins was easily within detector range before the erosion, but now all four are within easy detecting range.
That is one of the factors that makes it easy to find cobs after the beaches cut. Cobs that were at different depths and out of detecting range before erosion end up concentrated near the base of a cut. There are a few factors that determine how far from the wall of the cut they will be.
I must stress that what I have called "vertical concentration" is only one factor in determining where cobs are found and vertical concentration is only temporary. Those cobs will eventually be washed down into the surf or covered up by sand again.
I've watched as this process occurred on different occasions so I am pretty confident that it is accurate.
In a previous blog post some time ago, I described how the sand at the face of a cut was knocked down by one wave and then the washed away by successive waves hitting the face of the cut. When the sand was washed away, heavier or more aerodynamically shaped objects were left behind.
That is enough of that topic for now.
If you are Christmas shopping, there is a map of the Treasure Coast treasure beaches now listed on eBay. The item number is 110616713315.
Forecast and Conditions.
The wind is out of the west this morning and humidity is 100%. The west wind will keep the seas calm this morning. They won't increase much until Monday when they will increase up to six feet (if the surf web sites are correct) later in the day.
As I've mentioned before, six feet is about where you start to see some possibility of improvement in detecting conditions, depending of course, on other factors.
Take a look at low tide areas today and watch for possible small cuts on Tuesday.