Interesting note on depth.

[maverick4440]

I went out detecting today.
One of my neigbors was digging a hole for a new septic tank.
I just happened to be passing by and this caught my eye.
I live in a heavily timbered area in Northwest Montana.
We are in dense forest with 50 to 100 foot tall trees as far as the eye can see.
If it weren't for the massive charred stumps you stumble on in the woods you would never know that a catasrophic fire wiped this whole valley out in 1910.
It has completely reverted back to heavy timber in the last 97 years.
What I found interesting about the septic hole was the line of heavy charcoal showing how much soil has accumulated and built up on top of the original 1910 charred timber line.
I detected the charcoal line and found bits of man made metal items so I am posotive this was above ground in 1910.
What is amazing is that the soil has covered the charcoal at depths of up to almost three feet in some areas!
Some only has 18 inches of soil accumulation.
It makes me wonder how deep those really old coins could be.
If you look at the pics I put my detector in for scale comparison.
The hole is 4-1/2 to 5 foot deep.
You can see the line where the 1910 fire hit and also see how much soil has accumulated since.
Those old coins may be deeper than I thought in some places.
I really wouldn't have believed there could be that much soil accumulation since 1910.

 

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[gallileo60]

Wow, very interesting..I too, often wonder how much the ground height has raised over the years....

 

[lumbercamp]

It is very unlikely that that much soil accumulated in that amount of time. Most likely a machine pushed that dirt to that depth. This was discussed several months ago. Maybe someone could find the thread and repost it. If this was on the lowlands, floodwaters could have moved that much dirt.

 

[bakergeol]

I was wondering if that material was charcoal(from fire) or coal. Wack some of it open. If it is coal- a coal bearing bed and not fire related. Seems like a very thick zone for a charcoal layer.


George

 

[maverick4440]

I was wondering if that material was charcoal(from fire) or coal. Wack some of it open. If it is coal- a coal bearing bed and not fire related. Seems like a very thick zone for a charcoal layer.


George

It's wood charcoal.
I dug some of it out because I detected some old bolts in the burned section.
I think the heavy forest canopy contributes some to the depth.
This area is extremely dense forest.
We are the only pacific rainforest in the state of Montana.
It rains almost as much here as in seattle.
We also get a lot of tamarack needles falling evey year which could build up and decompose I suppose.

 

[diggerfororo]

I think your theory is sound on decomp. but if you look at the strata only the top 12 to 14 inches is new soil. The rest was most likely washed in when there was no ground
cover after the fire.

Les

 

[silverswede]

I just ran across your interesting post today, Maverick. I live not too far west of you in Idaho. We have quite a dependable indicator here on the rate of overburden from trees, wind, and water in the forest. The Mount St. Helens eruption in 1981 left a 1 to 3 inch layer of ash and it's still visible as you dig down. In those 26 years the deepest I have seen natural accumulation over it is about 6" in dirt and a foot or so under leaf, needles or other organic material. The 1910 fire took out much of this area also, like half the town of Wallace, Idaho. I have found coins and relics from the small town of Grand Forks Id. that was destroyed completely and never rebuilt that were on the surface still in 1976. Another thought is if you have any peat in the soil around your area as in a forest fire that can burn down many feet and leave metal that was on top of the ground very deep. Your research and speculations seem very right on the mark.

 

[rayredditch]

Over here, most things medieval, or even Roman/Celtic, can be just 4 inches dowwn, others about a foot, but very rarely deeper than that, unless it´s been deliberately covered over through the years (Building foundations) to allow the land to be used for agricultural purposes.
Even iron age is normally only 18 inches to 3 foot deep.