Peat soil and Dunes. False signals

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Saki
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Peat soil and Dunes. False signals

Post by Saki » Thu Aug 30, 2018 8:23 pm

Has anyone any advice on using the 400i on Peat soil.
I could walk for metres and metres and get no signal, then a good 77_85 no iron grunt, Go to dig and .....nothing. Lots of false signals. I take off the top layer, scan with 400i, signal,still there. .. use my carrot and cannot find it. Dig some more. Scan with 400i, its still there. I eventually give up and fill the hole in frustration. Widened and deepend...nothing!
Also, I was on a pasture field that is surrounded in dunes. Very Sandy loamy soil. And false signals EVERYWHERE. Actually went looking for an electric fence or electricity poles/cables... nothing.
Just gave up as the 400i was jumping all over the place. One thing of note is that the pasture, when dug is approx 10-12inch of Sandy soil, then peat. Black, black peaty soil.
Two permissions that really should be producing something.... but getting nothing but a lovely walk :)) :D


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Re: Peat soil and Dunes. False signals

Post by sweepstick47 » Thu Aug 30, 2018 8:52 pm

Power Lines:- Don't forget that in some locations, especially on village approaches, the power supply is often laid underground. In general, following the roadside verges. Regards ss47
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Re: Peat soil and Dunes. False signals

Post by Wigeon » Thu Aug 30, 2018 9:23 pm

Most of my digging has been on peat fen or fen-edge peaty mixture soils.

The peat really can be a bit of a devil for falsing sometimes. It seems to go in fits and starts in this area and is sometimes associated with a reddish coloured deposit that most likely originated from burning in the distant past.

A friend of mine is a chemist and he tested some of the reddish deposit for me, as I thought it to be some sort of iron oxide. However no trace or iron in it, so that theory went west.

The peat is very harsh on metals and will totally corrode even big lumps of iron in a relatively short time. Small iron stands no chance and I think this is one of the main sources of falsing. The object itself is no longer recognisable but its ghost or halo remains for the detector to pick up.

An example of this is a cast iron water supply pipe, installed around 1906 and removed in the 1960s and 1970s when it started to catch the plough as the peat shrank.
Even today, albeit long gone, it gives a very strong signal that sounds like non-ferrous, depending on how it is approached etc.

I dug some big holes along the line of the pipe until the penny finally dropped when I actually dug up a significant fragment of it.

Disappearing signals also seem to be a feature of the peat, that I suspect are created by similar factors to the falsing.
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Re: Peat soil and Dunes. False signals

Post by Saki » Thu Aug 30, 2018 9:38 pm

Wigeon wrote:
Thu Aug 30, 2018 9:23 pm
Most of my digging has been on peat fen or fen-edge peaty mixture soils.

The peat really can be a bit of a devil for falsing sometimes. It seems to go in fits and starts in this area and is sometimes associated with a reddish coloured deposit that most likely originated from burning in the distant past.

A friend of mine is a chemist and he tested some of the reddish deposit for me, as I thought it to be some sort of iron oxide. However no trace or iron in it, so that theory went west.

The peat is very harsh on metals and will totally corrode even big lumps of iron in a relatively short time. Small iron stands no chance and I think this is one of the main sources of falsing. The object itself is no longer recognisable but its ghost or halo remains for the detector to pick up.

An example of this is a cast iron water supply pipe, installed around 1906 and removed in the 1960s and 1970s when it started to catch the plough as the peat shrank.
Even today, albeit long gone, it gives a very strong signal that sounds like non-ferrous, depending on how it is approached etc.

I dug some big holes along the line of the pipe until the penny finally dropped when I actually dug up a significant fragment of it.

Disappearing signals also seem to be a feature of the peat, that I suspect are created by similar factors to the falsing.
Wigeon, that makes a lot of sense ::g While looking at the landscape, it seems to me that in these areas I might be wasting my time, as the peat is probably too deep. And the dunes areas are also too deep. Also, peaty soil seems to be below the 4 on the ph scale :D
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Re: Peat soil and Dunes. False signals

Post by Ladybird66 » Fri Aug 31, 2018 12:47 am

Ah, now that’s where a bit of gardening know how comes in useful. I’ve just planted another small Heather bed. My big one I took a lot of time with, making sure I got the ph level and the plants right. Some heathers will only grow in acid soil. What makes peat - Heather. Peat is Heather and it’s acid.
Needless to say that one was a big job. I’m older and a bit wiser now, bought some plants that like neutral ph soil ::g
Useful info about the fen conditions though. Might explain why one of my early permissions was almost impossible to detect. It was, for many years just scrub, mainly Heather and willow. Amazing how answers come along years after the event ::g

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