Metal Locators and Magnetic Minerals: Possible spurious signals from magnetic viscosity

[Anonymous]

Eric, Here is a link to my site showing a possible foundation of an old house using a PI detector. I would like to know from someone like yourself if this is possible using a PI. It's has been proved that a old home once was here.
The PI was used with a new device I designed to use with metal detectors called the Arc-Geo Logger.
You can see the plot here.
http://lrlman.com/Pages/Arc-Geo/PS_FT.htm
regards,
Tim

 

[Anonymous]

Hi Tim,
PI's were originally used in archaeological surveys to look for buried walls, foundations and ancient pits; as well as metal objects. To do this, there has to be a contrast between the wall, pit etc. and the surrounding soil.
If the wall is limestone, for example, and it is buried in a magnetically mineralised soil, then there will be a contrast. The signal will drop as you go over the wall. A buried fired brick wall may have a higher iron mineralisation than the surrounding soil, and the signal will rise when the coil is over the wall.
These variations can be very small, and are only seen if a data logger is used and the results plotted out at the end of the survey; which has to be properly gridded.
Eric.