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What is the rate of coin descent
- Thread starter opus
- Start date
It depends on the density of the coin and the density of the soil. The coin will sink until it meets the same density of the soil. I have dug 100 year old coins at one inch, and 20 year coins at 6 inches.
A lot of it also depends on moisture and vegetation. I've found that the more of each the deeper and faster the targets get. Out here in the desert I've found 1800's coins on the surface to an inch deep. In grassy areas, the insects, moles, gophers, worms and the grass move nutrients from below the coins to above them, not to mention the grass clippings being deposited above the coins. I think that sometimes it's not so much the coin sinking as it is soil being deposited on top of them that makes them deeper.
Critterhunter
New member
There is no rhyme or reason to depth until you hunt a site and judge how deep targets are. I've dug my deepest coins (around 11") at a site that has heavy clay soil. At my other sites with this type of soil you're lucky if silvers can reach say 7 to 8" deep max. Reason the one site has coins 11" (and probably deeper ones there too) is it sits a bit lower than the land around it and so gets very swampy at certain times of the year when it rains a lot.
Of course rich fine soil tends to sink coins deeper more uniformly, but I've dug 2 or 3" silvers in that type of soil too. Perhaps because that soil is staying drier being higher or something?
Yes, I've read the "density of the soil thing is how deep the coin will sink until it is equal in density to the soil", and to a large extent I tend to agree with that...BUT...Have you ever walked on soil that has been heaved up a bit due to freezing moisture in it? It's like walking on a spounge. The densitity of the soil has been changed and now it has lots of trapped air in it where the frozen moisture pushed it apart in tiny pockets all over. When that happens I think the coin can free fall more before the soil gets compacted again. Also, some coins end up being pushed shallower from this.
Best way to judge how deep silvers should be is how deep are the round tabs? 5 or 6"? Then bet on silver starting at least that deep and going deeper, because round tabs came out in the 60's. And, a coin is more dense for it's size than a round tab, so they will sink faster/deeper.
How deep will a coin sink at a site? I don't really go by the density thing in all situations because of the reasons above, but if I hit a lawyer of heavier soil (like clay) below finer soil I've seen coins stop right at that depth no matter how old they are. Now, they might still sink deeper once they hit that different soil, but now they are moving much slower, so in a way newer coins can "catch up" to older ones as they work through this barrier.
Of course rich fine soil tends to sink coins deeper more uniformly, but I've dug 2 or 3" silvers in that type of soil too. Perhaps because that soil is staying drier being higher or something?
Yes, I've read the "density of the soil thing is how deep the coin will sink until it is equal in density to the soil", and to a large extent I tend to agree with that...BUT...Have you ever walked on soil that has been heaved up a bit due to freezing moisture in it? It's like walking on a spounge. The densitity of the soil has been changed and now it has lots of trapped air in it where the frozen moisture pushed it apart in tiny pockets all over. When that happens I think the coin can free fall more before the soil gets compacted again. Also, some coins end up being pushed shallower from this.
Best way to judge how deep silvers should be is how deep are the round tabs? 5 or 6"? Then bet on silver starting at least that deep and going deeper, because round tabs came out in the 60's. And, a coin is more dense for it's size than a round tab, so they will sink faster/deeper.
How deep will a coin sink at a site? I don't really go by the density thing in all situations because of the reasons above, but if I hit a lawyer of heavier soil (like clay) below finer soil I've seen coins stop right at that depth no matter how old they are. Now, they might still sink deeper once they hit that different soil, but now they are moving much slower, so in a way newer coins can "catch up" to older ones as they work through this barrier.
WV62
Well-known member
Tom Slick said:
I am going with Tom on this one, I don't think coins sink unless they are dropped in a very wet area that has some kind of surface activity that will push the coins down. At one time I hunted the curb areas of the city and I noticed that in general the coins were found at a depth that was just below the height of the existing concrete curbs. You can step back in the street and look at the curb and see how much build up has accrued since the curb was installed. Now if the ground was disturbed at sometime the coins could be anywhere. Now I am not taking a stand, this is just what I have noticed over the the last 30 plus years of coin hunting in my area. It could be different for other areas. Just my take on coins sinking.
Ron in WV
About 25 years ago I got two signals about a foot apart, the first signal was a 1917 dime barely under the surface and the second signal was a 1978 penny at least 6 inches deep. It was an undisturbed site, no plowing or grading had taken place and that wasn't the first time I had found recent coins deeper than coins a 100 years older. I had also found an 1876 dime at an old church site that was less than an inch deep, three feet away a 15 year old coin was between five and six inches deep. So why were the newer coins so much deeper than the older coins? At that time my oldest daughter, who has a degree in civil engineering, plus a few others, was an assistant to the head engineer on a mall construction project. She is, or was at the time, a qualified, licensed Troxler operator, that's a nuclear powered machine that measures the density of the soil, and was using it to determine if the soil conditions would support the massive buildings. I asked her about the coins, how a new coin could sink deeper in a few years than an old one did in over 80 years. She said the density of unorganic soil is from 2.6 to 2.8 g/cm^3 and any object of greater density, incuding coins, would eventually sink until the density of the soil equaled the density of the object. The sink rate is determined by the difference in density, the greater the density the faster the sink rate. Contributing factors are vibration, rain, frozen soil, grass buildup, leaves and a few others I can't remember. She said even though the two coins I found were only a foot apart, there was enough difference in the density of the soil to allow the newer coin to sink faster and deeper. The pic is a chart of the densities of some of the common metals we hunt with metal detectors, you can see there are differences in the density of different metals and a major difference between most of them and soil. Whether that's actually what happens is beyond my meager intelligence, but since it cost a small fortune to send her to school to learn that stuff I'll buy it.
MarkCZ
Well-known member
In some areas were soil stays soft or muddy the coins will sink. But in most areas this may be the first couple of inches, top soil is formed by decomposition of vegetation.
So you have some settling and then you have an increase of top soil forming above the coin.
If the area is mowed and raked clean,
Leaves raked up each season,
then the top soil growth will be much less and the targets will be more shallow. But on the other hand if the grass clippings were left and the leaves, then the targets would be much more deeper.
In a park what I use as a gauge is those beaver tail pull tabs, I know that they were in use from 1965 to 1975. In our city park these have a layer about 3-1/2" to 5" deep (millions of them)
The park dates back to the early 20's so its safe to say that the deepest pull tabs are around 1965 so that leaves from 1920 until 1965 below that, or to say 1920 to 1964 is below the 5" range. Now this don't hold true in places in the park like around large trees where the root system pushes and moves the soil and in mounded areas where there is more run off.
Now you can do a little math to figure the rate of depth increase by taking the 5" range and saying that's the 47 year range.
Roughly that is 11 years for each inch, but the first inch or so may be a little faster.
But that's in our park, you would need to do some sample targets to gauge the depth of coins in your local park.
When I metal detector shop they have to hit my two year old 8" coin test garden to be a keeper! if it don't make the grade I know its not one to use for the deep coin hunting in the park here.
Much past the surface and I don't believe coins SINK in most cases, dirt will hold up a coin.
Mark
So you have some settling and then you have an increase of top soil forming above the coin.
If the area is mowed and raked clean,
Leaves raked up each season,
then the top soil growth will be much less and the targets will be more shallow. But on the other hand if the grass clippings were left and the leaves, then the targets would be much more deeper.
In a park what I use as a gauge is those beaver tail pull tabs, I know that they were in use from 1965 to 1975. In our city park these have a layer about 3-1/2" to 5" deep (millions of them)
The park dates back to the early 20's so its safe to say that the deepest pull tabs are around 1965 so that leaves from 1920 until 1965 below that, or to say 1920 to 1964 is below the 5" range. Now this don't hold true in places in the park like around large trees where the root system pushes and moves the soil and in mounded areas where there is more run off.
Now you can do a little math to figure the rate of depth increase by taking the 5" range and saying that's the 47 year range.
Roughly that is 11 years for each inch, but the first inch or so may be a little faster.
But that's in our park, you would need to do some sample targets to gauge the depth of coins in your local park.
When I metal detector shop they have to hit my two year old 8" coin test garden to be a keeper! if it don't make the grade I know its not one to use for the deep coin hunting in the park here.
Much past the surface and I don't believe coins SINK in most cases, dirt will hold up a coin.
Mark
Critterhunter
New member
One of the pet theories is that coins don't sink but instead the grass grows and as more compost is placed on top of the coin by the grass over the years the level of topsoil gets higher, and thus the coin never really sinks but just gets deeper by virtue of that. I can see how this would be possible and probably does happen in some places, BUT...If coins don't sink then why do gold rings sink in sand that isn't disturbed? In fact, I just read where a test was done and a gold ring placed in the sand only hours before was now 6 to 8" deep. No disturbance of the sand, and no grass obviously to grow higher and bury it that way. For that reason, if a coin or ring can sink in sand, a coin can sink in soil without any outside influences other than just being heavier than the soil.
As a side note, that gold ring/sand thing got me to thinking. Might be a waste of time looking for gold rings super shallow even in dry sand? Anybody digging gold rings on the beach at only an inch or two deep, or are they always say 6" or deeper? I don't beach hunt often but last ring I dug from memory in the sand was only about maybe 3 to 4" deep. But, is wasn't gold, so maybe the weight is what kept it shallow?
As a side note, that gold ring/sand thing got me to thinking. Might be a waste of time looking for gold rings super shallow even in dry sand? Anybody digging gold rings on the beach at only an inch or two deep, or are they always say 6" or deeper? I don't beach hunt often but last ring I dug from memory in the sand was only about maybe 3 to 4" deep. But, is wasn't gold, so maybe the weight is what kept it shallow?
giuhalftrack
Member
John-Edmonton said:
this is partially true, but for non liquid materials, we need to consider the friction between coin and soil, I'm very interested in this topic, and i think roots, insects, and eventually frozen water in soil, play an important role, moving soil helping coin to sink.
Les in the UK
New member
In dry sand a gold ring will sink slowly, but in wet sand a gold ring will sink quickly.
This is because in dry sand the many grains of sand act together to support the weight of the gold ring.
But in wet sand the ring weighs more than the surrounding sand as each grain of sand acts independently when wet, causing the wet sand to be lighter than the ring. causing the ring to sink.
IF you are looking for rings in wet sand you need to find the hard pack, the area of clay that is below the sand where the rings and coins rest on. After a storm when all of the lose sand has been removed this is the place to search as all the rings and coins that have sunk and been out of the reach of detectors are now exposed for us to find. happy hunting Les in the UK.
This is because in dry sand the many grains of sand act together to support the weight of the gold ring.
But in wet sand the ring weighs more than the surrounding sand as each grain of sand acts independently when wet, causing the wet sand to be lighter than the ring. causing the ring to sink.
IF you are looking for rings in wet sand you need to find the hard pack, the area of clay that is below the sand where the rings and coins rest on. After a storm when all of the lose sand has been removed this is the place to search as all the rings and coins that have sunk and been out of the reach of detectors are now exposed for us to find. happy hunting Les in the UK.
MarkCZ
Well-known member
So, some are saying that if I take a 55 gallon garbage can and fill it with dirt,
Pack it down,
spray some soil kill on it let it dry,
lay a quarter on top,
place a lid on it,
come back in a couple of years the quarter will not be laying on the top?
And that in enough time it will just sink all the way to the bottom??
I know of one internet theory were the guy states that rain drops beat the coins into the ground, LOL!
Think of it like this,
A tree bares leaves, then comes the fruit (seeds) the seeds fall first, then the leaves. The leaves blanket the seeds, the fruit rots this decomposition covers the seed and starts it germination.
Another case,
My property stakes. They are about three foot long and was drove in with only a couple of inches left above the ground, well they must be sinking because twice now I've had to find them with a metal detector and extend them.
Wooded areas where there isn't grass but just the once a year leave fall coverage and the top soil doesn't form at near the rate of a once a week mowed lawn where the grass clippings are left to decompose.
Sand on a beach is always moving sucking things down, but its also moves things up. The question is if you take a bucket full of sand shake it down really well and lay a ring on top of it will it just sink? Now if you move it, or vibrate it yes, it will for sure sink
Mark
Pack it down,
spray some soil kill on it let it dry,
lay a quarter on top,
place a lid on it,
come back in a couple of years the quarter will not be laying on the top?
And that in enough time it will just sink all the way to the bottom??
I know of one internet theory were the guy states that rain drops beat the coins into the ground, LOL!
Think of it like this,
A tree bares leaves, then comes the fruit (seeds) the seeds fall first, then the leaves. The leaves blanket the seeds, the fruit rots this decomposition covers the seed and starts it germination.
Another case,
My property stakes. They are about three foot long and was drove in with only a couple of inches left above the ground, well they must be sinking because twice now I've had to find them with a metal detector and extend them.
Wooded areas where there isn't grass but just the once a year leave fall coverage and the top soil doesn't form at near the rate of a once a week mowed lawn where the grass clippings are left to decompose.
Sand on a beach is always moving sucking things down, but its also moves things up. The question is if you take a bucket full of sand shake it down really well and lay a ring on top of it will it just sink? Now if you move it, or vibrate it yes, it will for sure sink
Mark