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  #181  
Old 05-29-2018, 11:10 AM
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Martin_V3i Martin_V3i is offline
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Originally Posted by MrNovice View post
Lol, in the Texas heat and droughts we have, they just fall in the cracks. No kidding, I've seen cracks in the summer more than 2 inches wide and over a foot deep!
Wide and deep cracks here in north Texas, get severe enough to force my neighbor with a horse farm to move their animals, and do a resurface with machinery. I've detected targets in a sidewall of a crack, which dropped out of sight with a slip-up. I left them, it was so deep.

Yes, ground cracks swallow targets.
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  #182  
Old 09-21-2018, 06:08 PM
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Originally Posted by Carol K View post
ABOUT COIN DEPTHS

Why are some older coins very shallow when newer coins are deep at the same sites? How can a new coin sink deeper in a few years than an old one in over 80 years?

The Density of Soil

The density of inorganic soil is from 2.6 to 2.8 and any object of greater density, including coins, would eventually sink until the density of the soil equaled the density of the object.

The Sink Rate

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.

How often the ground gets saturated can be a much bigger driver of coin depth than any minor differences in soil density. Until the ground directly beneath the coin becomes saturated to the point where the dirt becomes suspended in the water, and can move to the sides of the coin due to the coin weight, then little depth due to sinking can occur.

That's why many coins seem to end up in the 6-8 inch range - it takes a real soaker to move them deeper. So maybe the discrepancies in coin depth can be attributed to minor differences in the local drainage. The finer the soil particles, the easier they get suspended and the faster the sink rate.

Chart of Densities

Here is a chart of the densities of some of the common metals we find with metal detectors, also the differences in the density of different metals and a major difference between most of them and soil.

Looking at the chart below, the dime should sink a lot farther than the penny, because the gravity is twice as high on silver as copper is? I know I've found silver just under the grass and then dug 6" or 7" for a clad penny. Nothing worse than getting a deep signal, dig it and it's a clad penny!

The good stuff is sinking faster than the trash. No wonder not many gold coins are being found!

Density of Precious Metals

Platinum 21.45

Gold 19.3

Silver 10.5

Copper 9.0


Densities of Some Common Metals

Aluminum 2.7

Lead 11.4

Magnesium 1.8

Steel 7.8

Tin 7.3

Zinc 7.1

Iron 7.87
Nice post!!

Matt

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  #183  
Old 11-30-2018, 03:19 PM
Rick in Ky Rick in Ky is offline
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Dug a stinking Lincoln the other day
about 8" deep at a civil war site,wondered
how that Penny got that deep and the
Bullets where only around six inches deep,
You want just scratch head sometimes
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  #184  
Old 01-09-2019, 09:42 AM
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Default sink rate and fluid dynamics

I think it is a combination of densities of the medium, eg wet or saturated soil and fluid dynamics. But then I am not telling you anything that others are saying here.

The more wet or saturated the soil the faster the sink rate of objects with the same orientation and density.

Denser objects will sink faster that less dense objects in the same state of saturation.

The orientation of the coin will affect the sink rate. Say you have two 1964 silver quarters say six inches apart and the saturation of the soil is the same and of course the density of the quarters are the same.

But one quarter is laying perfectly horizontal to the surface and one inch from the surface. The other quarter is buried one inch from the surface and six inch to the left or right of the first quarter but is in a vertical or 90 degree angle from the horizontal surface. Or to put it another way is perfectly on its edge.

There is more resistance to sinking with the flat coin than the vertical coins. Simply because it is easier for the water soil mix semi-fluid to get out of the way of the vertical oriented coin because much less surface is presented to the underlying soil/fluid mix than the coin laying flat. The coin laying flat has the most resistance to the soil/fluid mix from moving away from the coin.

So you vary the coin orientation and density of coins you get a variety of results. Thus a lighter coins say a zinc penny in a vertical orientation can easily sink faster than say a buffalo nickel in a flat orientation.

The trouble is unless you dig all of them out still in the plug where you can see their orientation relating to the surface you cannot see how they were orientated in the soil.

I am sure there is someone experienced in fluid dynamics and calculus could puzzle out a formula, but that does not change what and where we find them in relation to depth. We just go out and hunt and find the coins the best we can.

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  #185  
Old 02-01-2019, 12:50 PM
k2gleaner k2gleaner is offline
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Originally Posted by Carol K View post
ABOUT COIN DEPTHS

The Density of Soil ...The density of inorganic soil is from 2.6 to 2.8 and any object of greater density, including coins, would eventually sink until the density of the soil equaled the density of the object...
The bulk density of solid rock (quartz) runs around 2.65 g/cm3 but that of any soil runs maybe from 1.0 (organic) to 1.33 (loam) and maybe 1.65 and up for a compacted soil, probably with a decent amount of sand in it.
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  #186  
Old 05-23-2019, 01:05 PM
Maxspin Maxspin is offline
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Picture/Video is worth 1000 words/posts
https://www.youtube.com/watch?v=n3wsUYg3XV0
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  #187  
Old 06-12-2019, 11:07 AM
Kojak Kojak is offline
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I live in Ct. When I was a kid my father would have me "turn" the garden every spring and remove the rocks. Every year there would be more rocks that got pushed up, and quite a large amount.

I guess it might be freeze-thaw action. If rocks can move wouldn't coins also?
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  #188  
Old 06-17-2019, 09:41 PM
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Originally Posted by woodbutcher View post
I agree with you on coins donít always sink far..I just dug a 1899 barber dime at maybe 3 inches,and a v nickel at maybe one inch,just under the grass.
right! makes ya wonder WHY we don't find a lot of stuff anymore!..live in new england,and been hunting for over 35 years.gotta tell ya, just about ALL my stuff
was found at the 5" to surface levels ,and this includes all 6 states.what does this indicate?..it indicates that even in the late 70's right up to the present day,ALL
detectors could get down to these levels,soooo therefore the available depth WAS sufficient, as any and all these detectors would have detected deeper beginning with THAT time period. it explains why sites have dried up over time, at least "here in new england!" stuff was already found down to those depth levels, and anything left is hiding in the "!!!!!" your mileage may vary in other parts of the country, but i suspect the search ranges are similar! ..just sayin'

(h.h.!)
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  #189  
Old 07-12-2019, 11:37 AM
MCH MCH is offline
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*
From this great thread I gather that the main factors effecting coin depths are: soil densities, coin densities, coin surface area, coin angle of decent, overburden from organic debris, slopes and the amount of preciptation to include flooding or lack of precipitation. Roots, freeze-and-thaw heave, worms, grubs, ants, burrowing mammals and surface compaction from foot traffic, live stock, parking areas, fair grounds etc. are players too. The period of time a coin has had all these forces acting upon it must also be considered.

There seems to be too many variables to say with much certainty - in most cases - the depth at which a coin might lie. This does not take into consideration the human activities involving fill dirt or tilling / plowing of farm fields.

Am I close? :-)

*

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  #190  
Old 07-12-2019, 12:58 PM
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Originally Posted by MCH View post
*
From this great thread I gather that the main factors effecting coin depths are: soil densities, coin densities, coin surface area, coin angle of decent, overburden from organic debris, slopes and the amount of preciptation to include flooding or lack of precipitation. Roots, freeze-and-thaw heave, worms, grubs, ants, burrowing mammals and surface compaction from foot traffic, live stock, parking areas, fair grounds etc. are players too. The period of time a coin has had all these forces acting upon it must also be considered.

There seems to be too many variables to say with much certainty - in most cases - the depth at which a coin might lie. This does not take into consideration the human activities involving fill dirt or tilling / plowing of farm fields.

Am I close? :-)

*
Nice summary.

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  #191  
Old 07-13-2019, 02:09 AM
jmaryt jmaryt is offline
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Originally Posted by MCH View post
*
From this great thread I gather that the main factors effecting coin depths are: soil densities, coin densities, coin surface area, coin angle of decent, overburden from organic debris, slopes and the amount of preciptation to include flooding or lack of precipitation. Roots, freeze-and-thaw heave, worms, grubs, ants, burrowing mammals and surface compaction from foot traffic, live stock, parking areas, fair grounds etc. are players too. The period of time a coin has had all these forces acting upon it must also be considered.

There seems to be too many variables to say with much certainty - in most cases - the depth at which a coin might lie. This does not take into consideration the human activities involving fill dirt or tilling / plowing of farm fields.

Am I close? :-)

*
certainly sounds accurate, however after 35 years in the hobby, and finding just about all coins at the 6" level to surface, will say that i could care two sh8ts less!
i can hunt for another 50 years here in "new england" and THAT is never going to be different.they will "still" be detected at the 6" level to surface, to include large cents, king george's,seated,mercs,barbers,chiefs,reales,tokens ,and revolutionary, and civil war relics...i'm just sayin'

(h.h.!)
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  #192  
Old 07-13-2019, 02:14 AM
jmaryt jmaryt is offline
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Originally Posted by Kojak View post
I live in Ct. When I was a kid my father would have me "turn" the garden every spring and remove the rocks. Every year there would be more rocks that got pushed up, and quite a large amount.

I guess it might be freeze-thaw action. If rocks can move wouldn't coins also?
yes! this explains why asphalt roads get heaved upwards in the winter, and pot holes appear.the the "sub grade" under the asphalt is shifting from the thaw-freeze cycles.and breaking the asphalt at the surface. anything contained in that soil is moving up and down as well.

(h.h.!)
j.t.
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  #193  
Old 08-10-2019, 05:21 PM
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Question coins small,medium or large

Why coins move around the ground is like a sponge when you wet it it opens up when it dries it closes.When it rains the ground opens its spores and lets in the rain,but as it drys starts to close and pushes the coins up.Hmmm thats my 2 cents worth.
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  #194  
Old 12-07-2019, 10:31 PM
k2gleaner k2gleaner is offline
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Oops. I didn't realize I had already said this in an earlier post.
Deleted.
Carry on. Nothing to see here...

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  #195  
Old 12-07-2019, 10:42 PM
k2gleaner k2gleaner is offline
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Originally Posted by Maxspin View post
Picture/Video is worth 1000 words/posts
https://www.youtube.com/watch?v=n3wsUYg3XV0
Cool, but that's just a tiny piece of what's being discussed here, unless you are saying that earthworms carry our coins up and down within the soil column!

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