Coin depth

Tom, I was reading something you wrote about how far a coin will sink in the ground based on the type of soil it's in. I live in southern Indiana in Jennings county and was just wondering if you knew how far a coin would have sank since the 1800's or 1900's. How deep would my detector need to be able to detect to find a lot of coins from that era based on the type of soil in my part of the country. Any info you can give me would be greatly appreciated. Kevin

I think that will be a next to impossible question for Tom to answer...Heck,where I live,my property has loamy soil,coins sink....but I can go feet away and its harder,rockysoil...stuff is shallow.

Welcome to the forum Kevin.
Sink rate depends on sooo many things, almost impossible to answer. Your can get a answer by digging old coins in each specific area you hunt, measuring depth, then average the depths in inches.
I have found 1800's coins from 0," down to 18-20" and everywhere in between. The deeper ones of course, were found chasing other nonferrous targets.

Tom covers a little site evaluation in "Inland" DVD there are exception's to the rule, low lying sumps- vegetation thick=quick sink rate. Places where vegetation is sparse, inorganic soil= slower sink rates. Read where he has detected the " Hoosier" State hopefully not where you hunt??? & HH



Edited 2 time(s). Last edit at 03/02/2014 06:14PM by rapidroy7.

Hi Kevin,

Welcome to the forum! If you have a moment...... you can go to the home-page and read an article titled "Love Is Deep" in the archives section.......... and there is a sink-rate article in the "Fisher Intelligence" section..... that you will (most probably) find the most interesting. Start there ..... and holler if you have more questions!

NASA-Tom Wrote:
-------------------------------------------------------
> Hi Kevin,
>
> Welcome to the forum! If you have a
> moment...... you can go to the home-page and read
> an article titled "Love Is Deep" in the archives
> section.......... and there is a sink-rate article
> in the "Fisher Intelligence" section..... that you
> will (most probably) find the most interesting.
> Start there ..... and holler if you have more
> questions!


Interesting article Tom. I have always been under the assumption that coins actually sink very little and they attain depth more by vegetation growing , being cut and decomposing year after year .I've found that coins I've found in wooded areas seem to be quite a bit shallower than coins found in lawn areas.

With the dynamics of the Earth........... coins certainly do sink do to other environmental factors ALSO!!!

Impossible question to answer as from one end of a football field to another the finds may vary due to that particular dirt and composition. Whats really interesting that find the approx. depth where old coins are found in an area and the other finds will be a similar depth. And silver dimes and halves included as one has more circumference but is much heavier. Indeed a subject that could be debated time and again and yes we have areas where silver dimes are 6 inches and others where the depth is more like 10-12 inches...

In 13 years of detecting I have not found a hard and fast rule about coin depth. However, I have discovered that the more sandy the soil the less depth on old coins. I believe it is because this kind of soil drains better and clay soils hold more water and therefore allow coins to sink easier.

I also hunt Civil War relics. Most minie balls are 6 to 12 inches deep. However, I have gotten minie balls where you could kick away the leaves and it is laying on top of the ground....go figure.

This is a complex topic, for sure. There is absolutely no disputing "coin sink rate" concepts in sandy-type soils of Florida, as NASA-Tom has very well documented.

That being said, I have significant doubts about this topic, in other parts of the country, where other types of soils prevail.

Here are some anecdotes to support my position; these are IN NO WAY to be considered a carefully-controlled, scientifically-valid experiment, but I put these thoughts out there, for what it's worth.

In much of Oklahoma, the soil is comprised of predominantly clay; even where a layer of "topsoil" exists, the background component is clay -- which becomes increasingly "dense" as you get deeper/beyond the layer where organic material is mixed in. That said, there is a park I like to hunt, that is 125 years old; it has been hunted to death over the years, as has been confirmed by some "old-timers" that I've spoken to, who pulled tremendous amounts of silver out of this park. I have hunted this park HUNDREDS of times over the past few years, and have come to some conclusions in the process. First, most of the "old" coins down to about the 6" level have been previously dug, by the "old timers." I could probably count on two hands the number of "old" coins (silver/wheats, etc.) that I have dug shallower than about 5" over the past 3 years. Meanwhile, I have dug well over 100 (probably over 200) old coins, in the 5 1/2" to 9 1/2" depth range -- the oldest ones from the 1870s, pre-dating the park by a couple of decades (but obviously dropped no earlier than 1889 to 1890, when the first settlers arrived and the park was first platted). In one portion of the park in particular, a friend (a very experienced hunter) and I found a concentration of old coins, with over 100 coins being recovered, dating between the 1870s and 1908 -- each ranging from roughly 6" to 9 1/2" deep, from an area probably 120' x 80'. We have hunted this portion of the park so heavily, that detectable coin-type targets are now virtually non-existent (we have not managed to dig a single additional coin from this portion of the park with ANY machine/coil, for roughly the past 9 months).

Now, it would be easy (but potentially false) to conclude that coins sink no more than about 9 1/2" deep at a maximum, in this park, based on these observations. The issue, of course, is that testing has ALSO shown that in this type of soil, with a relatively high iron content which gives the soil a reddish hue, 10" or so is about the depth limit of even the best machines (Minelab FBS units, Fisher F75 with boost, etc.) SO -- it's as NASA-Tom always says -- you can't know what you don't know; with roughly 10" being the maximum detectable depth, who is to say that there aren't MANY more coins that have sunk to deeper depths, beyond our machines' capabilities?

Interestingly, though, a couple of recent experiences have occurred that support this idea of coin "sinkage" being limited to about 9-10" in most cases, in our area. First, park officials recently undertook a project in this park involving excavation for a new pavilion -- roughly a 25x40 foot foundation required (this being roughly 75 yards from the center of the area where we found the concentration of old coins 6-10" deep). The ground was slightly sloped here, so the dozer operator "cut in" to the ground to make a level pad -- scraping roughly 6" of dirt from the "low end" of the slope, and about 2' of dirt from the "high end" of the slope. My partner and I knew this was going to happen, so we were there the day the dozer operator started his work -- certain that this would uncover some (perhaps several) old coins in that had sunk to the "next layer down." As soon as the guy finished for the day, my friend and I spent a couple of hours eagerly hunting this small, newly excavated area. Results? NOT A SINGLE COIN (again -- the new "ground level" was anywhere from roughly 6" to roughly 2 feet below than the previous sloping terrain, averaging probably 1' deeper than the prior ground level). This was a SHOCKING result for both of us. ZERO coins -- and in fact very few targets of ANY kind -- a couple of nails and pull tabs near the "shallow end" of the foundation, and that's IT. NOT entirely conclusive, but definitely an eye-opener.

Meanwhile, I also have been able to hunt to a very old (by Oklahoma standards) site with some mid 1800s military activity. In this area, among our digs have been roughly 2 dozen coins, estimated to have been dropped as early as 1850, including Seated half-dimes, dimes, quarters, and a half, and a handful of three-cent pieces. ALL have come from 4-8" depths. We have dug a few of the lead balls/bullets a bit deeper -- but nothing I know of deeper than about 10". Recently, some excavation/soil removal in parts of this site have confirmed that here also, not much exists deeper than the 10" - 12" depth...

FINALLY, shifting gears and moving 1000 miles northeast to my childhood home, in western PA, I have dug a number of coins from the first half of the 20th century from the 4-7" depth range, while back home visiting family -- but only a few older coins dating into the late 1800s. However, last summer, through research I located the approximate site of an old church dating back to the mid 1800s. The site is now "in the woods," where no visible evidence of the church remains, with the only telltale sign being the cemetery. Research reveals that the church burned around 1900 and was never re-built. After narrowing down the area where the church must have stood based on square nail concentrations, I was able to dig five coins from the surrounding ground -- two Indian Head pennies (one from the 1880s and the other near 1900), an 1853 Seated dime, an 1853 Seated half-dime, and an 1830 Bust dime (that was likely dropped in the 1850s -- based on the well-circulated condition of the coin, and the date when the church first became active). All five of these coins came from a depth of only 4-5" deep...near the bottom of an organic layer where clay content of the soil increased.

Adding these, and other, experiences together, it does not seem to me that a standard "sink rate" type of approach makes sense in the areas I hunt. In the Oklahoma park I mentioned above, I have dug many hundreds of "modern" coins as deep as the 3-5" depth range -- and some in the 5-8" range. My experience in this park leads to a conclusion that coins seem to reach 2-3" deep VERY quickly (by 5-15 years), and then sink to 3-4-5" depth over the next 50 years or so; at that point, "sinkage" happens MUCH more gradually -- and possibly even approaches zero.

So -- from my perspective, using a simple "sink rate" concept is obviously appropriate in some areas, but not so much, in others, based on my experience.

Steve



Edited 1 time(s). Last edit at 03/03/2014 07:26PM by steveg.

steveg = VERY good documenting/write-up.