How fast do coins sink?

[garety]

So how fast do coins typically sink?

I realize IT DEPENDs, upon soil type. But I am just wondering how deep do you have to go to find a silver coins? I have a lot of red clay type soil where I am at in northern California. I have a gold bug pro DP, so ground balance is not an issue. Been finding a fair amount of coins probably 3 or 4 every hour, and I have been going to various parks and stuff for an hour or 2 after work. I have found a fair number of coins as deep as 5 inches, but the oddest coin I have found so far is a 1965, quarter. one year shy of silver.

Also does some soil decompose coins fast? I have gotten lots of 2000s coins that are barely readable. Just trying to figure out if I am doing anything wrong, as most the sites I have been hunting have had people there for 150 years, but most coins I find are less than 30 years old.

 

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[enamel7]

This might be better asked in the detecting forum.

 

[vpnavy]

1st - I noticed this is your very first post - so - Welcome Aboard garety! You didn't list your state (or country) in your profile. So, you might consider jumping over to Sub-Forums: Select Your Area.... and selecting location information (i.e., clubs, hunts, finds, legends, maps, etc.) directly related to your state (or country).

2nd - I moved this request from Coins over to Metal Detecting for more exposure.

 

[Loco-Digger]

I live in ohio and have only found a couple virgin sites from the mid to late 1800's. The old coins were between 5 & 7 inches deep. On other sites that had some fill brought in (I presume) I have found coins as deep as 10 to 12 inches. The amount of rain, freeze/thaw, and worm activity are all related to how deep coins may go as well as the amount of leaves that fall annually and whether they get raked up or or left to decompose.

 

[Jason in Enid]

Coin DO NOT sink.

 

[smokeythecat]

Coins do not sink. They get buried. Things cover them up.

 

[garety]

Thanks for moving the post,

yeah, been lurking for a few weeks, but so far metal detecting has been a lot of digging up aluminum trash. I am guessing either parks and areas I have been going to have been either worked before, or silver coins are just particularly rare. I suppose move high ranked videos on youtube don't show the bust/fail days. so far have logged 20 or 30 hrs, 2 hrs at a time at various park, and have yet to find a silver coin.

 

[treasuresalvor]

Yeah,I wouldn't say coins sink but are covered or buried by several different methods depending on the area and soil/sand conditions. A more accurate word could be moved such as in areas with freeze/thaw cycles. Depth is never related to the age of the item. I've found 10 year old pennies a foot or more deep and 1800's coins an inch deep, right under the sod.

 

[cruiserkev]

Hang in there, took me over 50 hours to find my first silver, a '44 Washington quarter. It gets easier after that. Not much rhyme or reason of why coins get buried. Just the other day I dug a 2016 penny at 4 inches down, 10 minutes later I found a 1927 wheatie on the surface. Dig all good sounding signals and be patient. Good luck!

 

[WhiteTornado]

Welcome garety, you've got some great information already in the replies above. I would add that what matters most is where you are detecting and the history of that site. If the site is 150 years old but has had little human activity there over that time, that makes your chances of finding silver coins very slim. You may want to find some history of these parks and see if any big events were held there in years past on a regular basis (carnivals, expos, etc). Perhaps you can at least narrow your hunting areas down to the places where large crowds gathered.

The one useful thing I can say about depth and what you find is, are you finding junk several inches down? I was hunting an old city park once with a group. We were finding bottlecaps, screw caps, and pulltabs even 6-7 inches down or more. And all of that junk seemed relatively modern, especially considering it included screwcaps. We surmised the park had fill dirt brought in at one time.

Happy hunting!

 

[Mackaydon]

Here in California they can rise (or be buried deeper) during our floods or be buried deeper with our earthquakes.
Don......

 

[Charlie P. (NY)]

You have your answers: "it depends"

As far as silver I have found coins 2" to 12". I eyeballed an indian head cent (unfortunately because it was on flat shale and worn smooth on the face). Coins also rise because of floods, frosts, roots, tilling, grading, etc. The soil gets disturbed and redistributed regularly.

Great disappointment for me was digging a foot down on a weak but high signal and finding a 1986 clad Roosevelt dime. DRAT! It was a damp area that flooded regularly.


Modern coins have a lot of zinc and the acids in the soil (especially where nitrogen fertilizer is used) eat them up. The copper & zinc make a little galvanic reaction and they eat themselves.

 

[FreeBirdTim]

Coins do sink. Frost heaves, saturated soil in the Spring, insect activity and so on help to sink coins into the ground. The addition of leaves every year helps to cover the coins a little bit, but not much.

 

[sjvalleyhunter]

Coin DO NOT sink.

Didn't we have this very discussion a couple of years ago?

 

[sjvalleyhunter]

Here's the post/thread on the float/sink stuff...

http://www.treasurenet.com/forums/metal-detecting/442919-physics-items-sinking-ground.html

Cheers!

Skippy

That thread holds the record for my longest post on T-net. I really got on my soapbox for that one!

 

[FreeBirdTim]

If coins don't sink, then they must be covered with layers and layers of organic material over the years to obtain their depth, correct? So how come I find so many coins on edge in the ground? When you drop a coin, it falls flat. It doesn't stand on edge. So how on earth did it go from being flat on the ground to standing on edge? It sunk, that's how!

 

[Jason in Enid]

If coins don't sink, then they must be covered with layers and layers of organic material over the years to obtain their depth, correct? So how come I find so many coins on edge in the ground? When you drop a coin, it falls flat. It doesn't stand on edge. So how on earth did it go from being flat on the ground to standing on edge? It sunk, that's how!

Nope, completely wrong. Coins don't sink. They get covered by vegetation, soil and silt. They get stepped on, they go through heave, movement and rotation during freeze / thaw periods. They absolutely do not "sink". To sink means that something is carried downward by gravity through a medium. Coins can NOT sink through dirt. Don't believe it? put some dirt in a jar and place a coin on top. That jar can sit until the end of time and the coin will NEVER sink a millimeter without outside forces acting on it. When you have an outside force, its no longer "sinking".

 

[DannyB.]

I think they definitely sink if the soil condition are right; no doubt there.

My soil is sandy; they sink.

I've found whole beer cans , undamaged 12 inches deep. They sunk.

If you put a coin in a jar full of dirt; I guess it won't sink. Doesn't really count though.. cause there isn't any environmental influence.

To be fair.. I'd say they probably get covered over faster than they can sink in most instances. Depending on environment.

 

[FreeBirdTim]

We'll have to disagree on this one, Jason. Call it what you want, but coins are not 10 inches down because layers and layers of organic material have dropped on top of them. They are 10 inches down because they sank into the ground over the years. Why or how they sank into the ground is irrelevant.

 

[sjvalleyhunter]

Jason in Enid made me do it! He used his coin in a jar example again, so I am going to repost my original post from the aforementioned thread to explain why coins do, in fact, sink. So here it goes....

If someone were to drop a penny into a glass of water what happens? It drops through the water and to the bottom of the glass. The reason this occurs is because the penny has mass, and gravity takes an effect on it. In a simplified explanation, as gravity pulls down on the coin, the molecules of water under it move out of the way, or displace, allowing the penny to sink to the bottom. This is a fairly simple concept.

Now drop a penny onto the ground. Of course it doesn't disappear into the ground right away because the dirt doesn't move out of its way. However, over time it does. Some folks theorize that rather than sinking, the coin gets buried as dirt and organic matter is deposited on top of it. Although this contributes to the coin disappearing into the ground, the more influential factor is that the ground beneath the coin does actually move, allowing the coin to sink.

So taking the same principles as the water example, in order for a coin to sink the molecules beneath it (in this case the particles of dirt), have to move out of the way. This does occur by a variety of means.

First of all, and the most powerful, is water. Put a coin on a patch of dry dirt. Now wait for it to rain. After the rain stops, pick up the coin. Obviously the dirt will be wet underneath it. This is because the water flowed under the coin. What happens when water flows? It erodes the ground and moves the particles of dirt. Whether it be rain or sprinklers, we have now begun the slow process of moving the dirt particles out from under the coin. The sinking process has begun.

Now enter grass. When grass or other plants grow, they produce roots. Roots extend into the ground and under the coin. The roots move (displace) the dirt so they can take up the space they need as they grow. Any mildly experienced detectorist has dug up a coin that had been encased in grass roots. Well eventually those roots under the coin die. Because plant material is mostly made of water, when that organic material dies it decomposes and reduces in volume. What is left is a void, or space under the coin, where this small root once was. So what happens? This minuscule hole collapses, allowing the coin to ever so slightly fall (aka sink).

Let's add some earth worms into the mix. Worms essentially eat dirt. They take in dirt, digest the organic material in it, and discard the rest. So when a worm burrows under a coin, it leaves yet another void (hole) in the ground. Eventually the mass on top of this void, be it the coin or otherwise, is pulled down by gravity and the hole collapses and fills in the void. Well the coin has now sunk just a bit more.

Now let's add rain and snow melt into the equation. The water seeps into the ground and by simple physics, it will flow into areas of lesser concentrations of dirt. Basically it will fill in those voids left by dead roots, worms, etc. And when water flows, it causes erosion. Dirt is moved which allows the coins to sink further into the ground.

This is why most coins, even the oldest of colonial ones, are typically found no more than ten inches deep. This first few inches is where there is the most activity in the ground occurs. The roots of grass and other foliage only grow so deep. When it rains, water only soaks so far into the ground. Worms and bugs eat organic material so they burrow only as far down as they need to find food. For these reasons, coins don't sink farther and farther into the ground over time. They do reach a limit because at some point there is very little occurring under the coin to cause the dirt to move. But they absolutely DO sink some over the years.

I mean no disrespect, but the jar example that Jason In Enid gave is flawed. Of course a coin dropped into a jar dirt won't sink. But that jar and its contents aren't exposed to any environmental factors, such as weather, plant growth, etc.. A closed jar is a static environment. The real world is not.

If you still think that coins don't sink and instead are covered up over time, think about this. My family owns a house that was built around the turn of the century. I have hunted the property and have found many old coins along the cement walkway that leads to the house, as well as along the cement sidewalk in front of the house. These coins are routinely five or six inches deep, below the level of the sidewalk and walkway. So if you subscribe to the theory that coins don't sink, then it would have to be concluded that the sidewalk and walkway have raised up five or six inches over the years. And since the walkway to the house still meets the foundation of the house at the same place it did 100 years ago, then it would have to be concluded that the whole house has also raised up five or six inches over the years. And this was all occurring while the coin was staying in the same spot on the ground and just being covered up. Obviously this isn't what happened.

Water, plants and worms aren't the only factors that contribute to coins and other objects being able to sink into the ground. The freezing and thawing of the ground during the seasons can have an effect, as well as other things. But the bottom line is this: over periods of time and with the right conditions, coins do sink into the ground. The rate by which they do and the depth that they get is determined by a number of factors.