WHY DO COINS BURY THEMSELVES?

hissinroaches

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May 25, 2009
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MD Dog

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Feb 10, 2007
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I've tried to explain this phenomenon before but some people are stuck on weird science. It all has to do with density. each type of coin has a specific density as does the soil it falls on. Once it penetrates the grass roots area this plays more prominently into the system. The coin will reach a place within the soil matrix where it's same specific density is reached. this same system can be demonstrated with liquids using liquids of varying densities differing densities will create separate layers. If you pour a liquid into this layered environment all will be mixed for a short period but it will al settle out again into separate layers with the added liquid seeking out a similar density level as its self. If none are found it will form a new level. So it is a coin dropped onto the soil will sink until the surrounding soil equall its specific density. As to why stones are forced to the top from a frost freeze action. It is the same. Although most stones are harder than surrounding soil the relative density can be less.
 

jlb783

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Dec 1, 2008
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MD Dog said:
I've tried to explain this phenomenon before but some people are stuck on weird science. It all has to do with density. each type of coin has a specific density as does the soil it falls on. Once it penetrates the grass roots area this plays more prominently into the system. The coin will reach a place within the soil matrix where it's same specific density is reached. this same system can be demonstrated with liquids using liquids of varying densities differing densities will create separate layers. If you pour a liquid into this layered environment all will be mixed for a short period but it will al settle out again into separate layers with the added liquid seeking out a similar density level as its self. If none are found it will form a new level. So it is a coin dropped onto the soil will sink until the surrounding soil equall its specific density. As to why stones are forced to the top from a frost freeze action. It is the same. Although most stones are harder than surrounding soil the relative density can be less.
:icon_scratch: Huh?
 

lastleg

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Feb 3, 2008
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I think he was explaining how gravity works. Any object with
weight will sink until it reaches a layer of density that keeps the
object from sinking farther.
Natural gold is extremely dense. When you pan for color the
gravel looks much denser to the eye but when you keep bumping
the pan while you allow the lighter sands and gravel to run over
the riffles even the ultra fine particles of gold will settle under
everything else.
Sometimes coins, unless they are on edge, won't get very far
down but every year the soil above is being replenished with dust,
plant matter and leaf mulch. The longer in the ground the deeper
they get without any external force.
You can easily see this by looking at old sidewalks or curbs. The
ground level eventually gets several inches above the paved layer.
 

MD Dog

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Feb 10, 2007
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jlb783 said:
MD Dog said:
I've tried to explain this phenomenon before but some people are stuck on weird science. It all has to do with density. each type of coin has a specific density as does the soil it falls on. Once it penetrates the grass roots area this plays more prominently into the system. The coin will reach a place within the soil matrix where it's same specific density is reached. this same system can be demonstrated with liquids using liquids of varying densities differing densities will create separate layers. If you pour a liquid into this layered environment all will be mixed for a short period but it will al settle out again into separate layers with the added liquid seeking out a similar density level as its self. If none are found it will form a new level. So it is a coin dropped onto the soil will sink until the surrounding soil equall its specific density. As to why stones are forced to the top from a frost freeze action. It is the same. Although most stones are harder than surrounding soil the relative density can be less.
:icon_scratch: Huh?

Try it your self, try using different coins and different liquids with different densities. Like oils of different types and Honey and syrups etc. You'll see them set up layers, then toss a coin in and see if it sinks all the way to the bottom or if you have a liquid that is just as dense as the coin, it will stop at that layer. Same thing with stones or rocks, at least until the bigger rocks reach the upper four feet in a frost zone, then it can be both moved up and or down in the soil matrix at varying points of time throughout the year.
 

lastleg

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Feb 3, 2008
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MD: Have you experimented with clad vs silver in the heavy
syrup/honey test. I think that would be interesting for all to
hear about.
 

Eu_citzen

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Sep 19, 2006
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MD Dog,
Wow I always thought the coins felt a bit "down". :wink: :laughing7:
J/K.

Now but seriously I think you got it quite right.
 

lastleg

Silver Member
Feb 3, 2008
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Uh-oh, MD, we forgot to take the specific gravity of gasses
into the formula. This may take all day.
 

MD Dog

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Feb 10, 2007
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lastleg said:
MD: Have you experimented with clad vs silver in the heavy
syrup/honey test. I think that would be interesting for all to
hear about.

nope sure haven't, but it does sound like an interesting thing to experiment with.
 

MD Dog

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Feb 10, 2007
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lastleg said:
Uh-oh, MD, we forgot to take the specific gravity of gasses
into the formula. This may take all day.

Feel free to work on that last leg. Me I don't really care but just like to hunt them and dig them up. ;D :D :wink:
 

Tom_in_CA

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Mar 23, 2007
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MD-dog, I got the chance a few years ago, to see this first-hand, in a perfectly stratified park-scrape in a late-1800s San Francisco park. They were scraping to make ready for astro-turf, and it was a rare occasion to be in on various levels of the scrape. The park was essentially un-hunted, because it was in a blighted neighborhood that local md'rs avoid (tending to go to the cleaner upscale parks, unless they want to punish themselves with clad and wino-caps).

The top 6" was very stratified: Ie.: clad within the top several inches, '50s/60s coins starting at 4 to 5", '40s losses at 6" or so, '20s/'30s losses at 7", etc... What was interesting, is that ........ if a person were merely to look at the age verses depth speed, of the top few decades, he could assume that ........ if that speed of burial continued, then by logical conclusion, a coin that was 100 yrs. old, would be a foot or more, right? But we noticed that once the scrape got down to 10" to 12" deep, where we could dig un-disturbed coins (which were now very shallow d/t the scrape), we could see that barbers lost in the teens, and seateds lost in the 1870s, were nearly identical in depth (with maybe a slight 1" difference). That meant that once coins got to a certain depth, the sinkage rate slowed and then, I guess, stops. Below a certain point (when the scrapes got to 1.5 ft. or whatever), the soil was completely sterile. So yes, there does seem to be a point where, in un-disturbed turf, coins tend to slow and stop their depth drop.
 

MD Dog

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Feb 10, 2007
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That's awesome Tom I wish you could have gotten pics it would have been really cool to be able to see it demonstrated in that way. Thanks for the post non the less, I'm just jealous I didn't get to see that.
:-\ :D :wink:
 

curbdiggercarl57

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But then you have to take in account of wind, water, etc., erosion, removing the upper layer. Personally, I think that they are just self conscious.
 

Seamuss

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jlb783 said:
MD Dog said:
I've tried to explain this phenomenon before but some people are stuck on weird science. It all has to do with density. each type of coin has a specific density as does the soil it falls on. Once it penetrates the grass roots area this plays more prominently into the system. The coin will reach a place within the soil matrix where it's same specific density is reached. this same system can be demonstrated with liquids using liquids of varying densities differing densities will create separate layers. If you pour a liquid into this layered environment all will be mixed for a short period but it will al settle out again into separate layers with the added liquid seeking out a similar density level as its self. If none are found it will form a new level. So it is a coin dropped onto the soil will sink until the surrounding soil equall its specific density. As to why stones are forced to the top from a frost freeze action. It is the same. Although most stones are harder than surrounding soil the relative density can be less.
:icon_scratch: Huh?
Huh, hell pay attention.

It's a highly logical phenomanon, Spock.


Coins gravitate. Dirt levitates.
 

RGINN

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So MD Dog you are saying that 'soil density' would explain why I found items 125 years old at one site only a 1/2 inch deep, but in another different area 20 year old items were only 4 inches deep? That's pretty cool, and there should be some use I could put that knowledge to.
 

MD Dog

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Feb 10, 2007
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RGINN said:
So MD Dog you are saying that 'soil density' would explain why I found items 125 years old at one site only a 1/2 inch deep, but in another different area 20 year old items were only 4 inches deep? That's pretty cool, and there should be some use I could put that knowledge to.

I'm not sure how you could put that knowledge to use RGINN ? :dontknow: Maybe if you could quantify the specific density of targets before hand and then have a way of matching it to soil conditions at your site you could make educated guesses aka estimates about depths of certain types of targets. But all that would be more work than it may be worth. Personally for what it's worth I still just swing, detect, dig. ;D :D :wink:
 

Tank69

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very intresting I never knew that :icon_thumright: thanks for the lesson
 

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