How fast and how deep do things get buried underground?

[tuone]

How fast and deep do things get buried underground?

at what depth do things go into the ground every 10 years? and after a century? and after a millenium?

What is the difference in burial rate between sand, clay, broadleaf forest, arid forest, grassland, etc?

I am guessing that coins take about 50 years to move 4-5 inches into the roots that jumble things up, and then they go slower once they are under a root line? so really the only thing burying the metal is the roots and animal movement that makes voids around the metal and make organic matter build up on top?

there is a 2000 year old fortification near where i live, but i figure after that long, will i have a decent chance of signals 6+ inches deep that are recent?

 

[Talon]

As far as that fortification goes, maybe the place to try would be farm fields in the surrounding area. Habitation would spring up around fortifications, and if anything was lost there, then maybe the plows are turning it up. I do seem to find lots of 5yr or less coins down 4 inches or more, they seem to work their way down pretty quickly but I don't know how far they keep going.

 

[Frankn]

Here's how it works. Things don't sink in the ground, unless it is wet like a swamp. They are covered by decaying vegetation, blowing winds and flowing water. I have seen objects on the ground year after year in the desert. No dying vegetation to cover them. I have recovered an ax head at about 10" in a grassy lot of a 200 year old house. So you see it depends on the vegetation more than the soil. Think about it, if things sank in the ground, there would be no headstones showing in the graveyard.

 

[Sandman]

Frankn is right of course. Things don't sink, they are covered up. Of course something could get stepped on or fall into a void. Roots can lift a coin toward the surface and stop the decent of a gold ring. I once found a man's wedding band with a large tree root growing through it.

 

[deepskyal]

I have no idea. Common for me to find coins from the 1980's and 90's at 4 or 5 inches, coins from a couple years ago at 2 or 3 inches in parks...and stuff from the late 1800's just under the surface in the woods. Maybe foot traffic and pressure push then down too, on top of the grass cutting building up Whatever...I like finding them.

Al

 

[U.K. Brian]

Last week I was digging eighteen hundred year old Roman from the surface to two inches and some modern from ten so you can't go by depth. Last winter I had a frost crack across a test bed and a fairly large copper coin just disappeared out of range.

 

[wayland]

Doesn't the freezing and thawing of the ground actually push some item to the surface?

 

[Frankn]

Wayland, When frost pushes things up, everything on top of them is also pushed up. When the thaw commences, I imagine everything slowly settles back down.

 

[wayland]

Frankn, I appreciate the info. Have a great day.

 

[NOLA_Ken]

What you're thinking of is "Frost Heave", it doesn't generally affect small items, or items that are buried deeper than the frost line. It's the reason that the foundation footers for houses need to be at certain depths depending on the region you live in, too shallow and the frost heave can cause them to buckle and break. It's really hard on driveways and sidewalks and can tear them up pretty bad. Here in New Orleans we have the opposite, in the summer the head causes roads and curbs to break all the time. Also the high water table has been know to float things out of the ground here, most notably caskets which is why the cemeteries have the above ground crypts.

I have heard of things being pushed up by the frost though, although I've never seen it happen. I suspect it's kind of an old wives tale, but I could be wrong.

 

[wayland]

Thanks for the info.

 

[worldtalker]

I find in parks and ball fields things can get rather deep,woods hunting at times surprises me at the shallow depth of something that has been there for hundreds of years!! God Bless Chris

 

[Diggin-N-Dumps]

I know here in Texas.. when the summer comes along..the ground has cracks in it that are 12-24 inches deep..and about 2 inches wide..so theres no telling what could happen...thou there are times i dig a coin from the 60s 5 inches deep..then find a coin from the 20s almost on top of the ground at the same place

 

[Frankn]

know there are no hard and fast rules. I have found $5 gold coins at 1" here in Maryland.
No this one is a $20

 

[worldtalker]

I knew some boys back in High School that jacked a 64 Vette and it literally got buried rather quickly,unfortunately for them the Cops found it rather quickly! God Bless Chris

 

[cra61]

If you don't believe frost lifts things, try gardening in New Hampshire. Every year a brand new crop of rocks!

 

[wheatymike]

I was at an old house place with a friend. I didn't have my detector with me we were riding dirt bikes. We got off to take a brake and I was standing next to some pretty flowers thinking this would be a nice place to bring my detector and hunt. I looked down on the ground right below my feet and there was a 1944 Mercury dime in a bare patch of dirt. Go figure.

 

[Sir Marc]

Like Frankn said, things get covered. Object get covered up with soil that is washed down a nearby hillslope or by layers of silt that are left behind after flooding, for instance.

For most detectorists in parks and lawns something else plays a much more important role. Namely earthworms. Darwin (yes, the one that wrote “on origin of species”) did research into the phenomenon that earthworms cover objects up with soil. Earthworms do this by eating soil and defecate that on the surface again. Theses worm turds are called worm casts. They eat soil to get nutrients from it and it is a way to move through the soil. They literally eat themselves through the soil.

The speed at which this happens is, of course, dependent on the amount of worms and the degree of worm activity. Worms love a clayey or loamy soil, preferably a little limey and not too dry. In “perfect conditions” objects get covered up quickly, sometimes with 1 cm per year. Eventually, again under the right conditions, object can be covered by a 30-40 cm thick layer of worm-poop (consisting of soil particles).
Drought and extreme cold make earthworms less active. In extreme droughts, like one encounters in desert environments, there is no worm activity at all and old stuff can lie on the surface.

Even under for earthworms favorable conditions ancient objects can still end up at the surface. For instance because the layer of worm casts is eroded by rain or wind. Or objects can be brought back to the surface by moles. Archaeologists who are looking for old sites on grassland always look inside molehills. These often contain artefacts that are pushed up together with the soil that forms the molehill.

To summarize:
Worms excrete digested soil on the surface and this way cover objects with a layer that can be as thick as 30-40 cm. At the beginning this process can be fast (1 cm each year) but as objects get deeper in the ground it starts to slow down. In the mean while objects can be brought back again to the surface by larger animals (moles, rabbits, badgers etc.) and the process of covering up by worm poop is started all over again.

This concludes my very first reply on this forum. Hope this was helpful. Sorry for my bad English, I’m foreign. Have a nice day, Marc.

Further reading:
Darwin, C. R. 1881. The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray

Especially chapter III on how fast and deep things get buried underground.
http://darwin-online.org.uk/content/frameset?itemID=F1357&viewtype=text&pageseq=1

Van Nest 2002 on 2000 year old artifact that get buried to a depth of 30-40 cm deep in western Illinois.
http://alliance.la.asu.edu/rockart/scans/ArtifactMovement.pdf

More worm knowledge for uber-nerds

http://darwin-online.org.uk/content/frameset?itemID=F1357&viewtype=text&pageseq=1

 

[Sir Marc]

Tha last link fot uber-nerds should be:

http://alliance.la.asu.edu/rockart/scans/CantiEarthworms.pdf

 

[Frankn]

The worm thing got my interest up a while back and I did a bit of reading and a bit of actual "worm gazing". Contrary to popular belief worms don't eat in front and excrete in back as they go. Worms have a slimy excretion through there pours that helps them slide thru the earth and absorb food thru there pours. They move thru the ground by expanding there body then narrowing down there leading end and pushing it forward. they then expand the lead edge and pull the rest of the body thru. You can see this action when they are on the ground also. I have seen them also leave droppings on the surface. Well that's 2 euros worth of my experience on worms. Frank