Coin depth-------A discussion

[treasure sstate]

I have seen posts where someone will state that coins sink. I believe that coins do not sink; exceptions would be where water action would cause coins to sink or an earthquake. I am referring to coins in a lawn or similar ground covered in vegetation. Grass grows and is mowed or dies and returns to soil there by causing a coin to become deeper as years go by. Now my reasons for this statement. In 1964 in my area we had what they call a hundred year flood and our Woodland Park was under about 5 feet of water. At the time I was away from home and returned in 1969 and started hunting this park. I retrieved (and still do for coins to 4 inches) my coins by using a brass probe to touch the coin and a 1 1/2 inch diameter tube (part of a sink trap) to plug the coin. About an inch down was about a 1/4 inch thick brown line of soil left by the flood waters. Over the years the line got deeper until around 1975 or 76 it disappeared at about 3 inches. No coins minted after 1964 was ever found below this line.

Coins are at different depths in different places. I believe this is due to amount of vegetation deposited on the coin. I made a 3 week trip around my state this spring detecting different parks. In one park the grass was cut and left where it lay, it was a lush and heavy thick grass cover. I found a 2001 quarter at 4 inches, if coin was lost in 2001 that is a rate of four tenths of an inch a year. In another park the grass was blown into a large container pulled behind the mower and the clad of the same age group was 1 1/2 to 2 inches down. Also in my area a part of a school grounds was mostly dirt and a few weeds. Over the years I have found 26 wheat pennies and 5 silver dimes from this area and none were more then 2 inches down.

So this is my observations and conclusion as to how coins are buried and why they are at different depths. Not a scientific study by any means so feel free to disagree I could be wrong; but I don't think so.

 

[JamesBondaka]

I think you are mostly correct. There is no reason for coins to sink other than the fact of gravity. Being that all things are of similar content thus gravity effects all things unifomally. In other words, IF, gravity causes coins to sink, it would cause everything else to sink, at a equal rate. I think that... as you say, grass gets cuts, leaves fall from trees, dirt gets moves around, therefore things just get buried accidently and more and more matter continues to cover the object...and everything else as well.

 

[Crispy Critter]

I agree with both of you.

 

[moonshine]

I firmly beleive BOTH that coins sink, and are also covered. (and can also be UNcovered) From what Ive seen Id guess that 30-40% of a coins depth is from sinking and 60-70% from coverage/uncoverage.

copper has a specific gravity of 9, soil has a specific gravity of around 2.6. Add water (rain/snow/dew), vibrate (root action, foot traffic, bugs, worms, etc.), and the copper will sink. the wetter the soil, the faster the soil/coin mixture will seperate.

in extremely wet, soft soil this is so obvious. the kind of soil thats "puffy" and your digger just sinks right into it. old coins arent gonna be in the top 2" and its not because of coverage, its because the dense coins sank through the much less dense soil.

take this soil to the extreme and call it a thick milkshake. you could put a penny on top of a milkshake and it would stay there, but if you vibrate it a little bit it will eventually sink to the bottom.

the soil always has some vibration in it. soil is not inert. (unless you take some and put it in a jar and put the lid on it, killing all the bugs, keeping water from flowing through it, keeping traffic off of it, etc.)

i work with soil in construction as well and i just cant rationalize that something much denser than soil wouldnt be able to sink through it if the soil was wet and allowed to move and vibrate. ive seen it happen. you can walk on wet muddy sand but if you stand in one spot and move your feet you can turn the sand into mud and youll sink right in.

also there are so many different types of soils. theyre all different.

"water action would cause coins to sink or an earthquake" in my mind i see soil as always having some level of water content and some vibration as a constant, although fluctuating, natural state. coins would sink on a geological time scale. the less dense the soil, the greater the water content, and the more vibration, the faster they will sink.

i guess my bottom line is this....coins are denser than soil....how can they NOT sink through soil (although at an extremely slow pace)....that doesnt make common sense to me.

 

[gitterdug]

I heard years ago, from some scientist, that due to leaf decay, soil splash (from raindrops, foot traffic, or animal), that the average coin is covered by 1/16 inch per year. This has held pretty well true, from my observations. Of course, due to heavy soil expansion/contraction, the coin could sink at a substantially greater depth if it exposed sufficiently within a crack, that gravitational forces would cause it to fall (i.e. more than enough coin was over air space within the crack to overcome any adhesive forces which bound it where it lies.

Using that figure, it would take 160 years +- to get to 10 inches. Now, obviously, as stated above, a barren area would not sink to such levels, but think.....how do the archaeological tombs, etc., get buried? Through blown sand probably, over the millennia.

Regardless, I have found 100 year coins at 2 inches, and 10 year coins at 8. It is what it is. LOL I am just grateful that I have a Minelab that reaches most coins that I come across, and they are rescued from certain death, buried alive no more......

Dennis, who realizes that 50% of the scientists graduated in the lower half of their class........

 

[moonshine]

ever notice how in a box of Cracker Jacks all the peanuts are at the bottom of the box? why is that? think about it. gravity is pulling all things equally, so why do the peanuts end up at the bottom? hmmm...i can see a flaw there though.....maybe because the nuts are smaller.... all right how about this one....take a pillow case and put 100 golf balls and 100 ping pong balls in it and shake the bag a little bit.....do you think you would end up with a uniform, homogenous mixture of ping pong balls and golf balls or would the golf balls mostly be at the bottom of the bag.

 

[wvrick]

I think it all has a effect on coins: rain, gravity, vegetation, dust and decay. Look at how much dust and dirt collects on your homes exterior every year.

 

[RandyNorthridgeca]

You might have already read Fisher Intelligence by Thomas Dankowski but if you haven't google it. It's an interesting read! He has a section about soil conditions and sinking targets. You use to be able to download it free from the Fisher website. Don't know how the coins get as deep as they do I just want to be able to hear them

 

[Crispy Critter]

I agree with all of you. Does that mean that I am an appeaser?

 

[Ray-Mo.]

I am of the school that believes coins sink very little in normal soils without any sand mixed in as in black or clay type soils.I have found way to many coins that were obviously lost over 100 years due to dates and lack of wear that were less than 1" deep.Most were found in old growth timbered areas that had no soil disturbance other than wildlife traffic.

This is here in central MO and one might ask why all those leaves did not form mulch and then soil to cover the coins much deeper and the answer is that the timbered areas I mention were and are burned off every few years thus no build up/covering.I have found numerous Indians and barber/ seated coins on top of the ground that had never sank any at all.Some were an inch or two and perhaps had not been burned over as often or the dear and turkeys had covered them a bit while foraging.

Also the forest canopy neutrilizes the pounding raid drops to a great degree taking the rain out of the equasion.

Sand and continual sloppy mud might be different and moles and other soil moving vermin could and will make a difference no doubt.Dust alone can form a lot of coverage in very dry climes.

As a side note I have found flint shards and arrow heads left from the Indians making arrow heads many hundreds of years ago that are still on the surface or near surface in these same forested undisturbed soils.

 

[John LA]

n/t

 

[moonshine]

well it is a fun thing to think about because there is so much to it. the shape and weight of the coin, the soil structure, the lay of the land...one of the oldest coins i ever found, a dateless 1/4 reale, "floated" (i think) somewhat along a slight slope and i beleive actually rose up if anything, if it was covered. (it was so thin) it was only an inch deep or so if that. lawn areas deifnitely seem to create the most "new" dirt from what ive seen.

 

[mcb613]

Great topic. Notr sure what to believe. I do know that I have found coins older than 100yrs, within a couple inches. Also, noted that these shallow coins wer ein very dry soil, ussually on a hump or high spot. Other very modern coins found in as mucha s 8" is very damp soil. So I guess I believe the soil moisture has a big role in the sinking of coins. HH mIke

 

[AL KS]

Ever notice in the older parts of a city the sidewalks are below ground level. And in some they had brick side walks and they are covered by an inch or sometimes three or four inches of soil. I agree with bout all of the above theories. They sink some and are covered some .......also there are variables such as moisture, cracks,soil composition.........and so on. Thats my two cents worth.

 

[JamesBondaka]

I have to stick to my original theory that coins dont "sink' BUT yes....I can see IF, the coin is in really dry soil(powder)or really wet sand etc...AND theres a big earthquake or something to cause extreme vibration.. I can see that it would sink... but in normal type conditions..., I think it would just "stay" where it is....until covered by grass, leaves etc or as one person pointed out....Just dust! You have to consider that the coin is being pushed down by gravity BUT, there is lots of earth, rocks etc etc to get in the way of that force. With all things being equal...the gravity is the same for all things...so "maybe", coins do sink BUT at the same rate as those rocks, earth and everything else.