Gradiometer kit

[John]

I have some questions about the gradiometer kit made by Carl Moreland.I'm hoping to discover if a gradiometer could help me find locations of subsurface structures and or other materals possiably discarded at indian camps.If so could someone tell me what to expect performance wise from this machine as far as depth and accuracy. Also I would like to build an earth resitivity machine. I have instrutions on Robert Becks machine. But would appreciate any info on any ERM's that may be better for Thunting and artifacts hunting applications.
Thank You for you time in these matters.
John

[Phil Barnes]

Re: Gradiometer kit

Every gradiometer magnetometer is a differential magnetometer, which is to say it detects and measures anomilies (Irregulatities) in the earths magnetic field caused by the presence of IRON. No iron, no anomolie.

If indian firepits contain iron then a magnetometer may detect them.

As to detection depth, Detection depth is a function of the mass of iron present. Lots of iron, good depth sensitivity.

Phil

[Willy Bayot]

Re: Gradiometer kit

It is indeed true that iron (or any ferro-magnetic metal) is easily detected with a differential magnetometer or a gradiometer. However, underground anomalies can be detected with a sensitive magnetometer (or gradiometer) even in the absence of iron because the ground that has been disturbed by man-made construction (or digging) has a different magnetic behaviour than the undisturbed ground around it. It is then possible to detect pits, wells, tombs whether filled or not. A camp fire (or firepit) used regularly for some time can also be detected because the high heat cook the stones around and makes their magnetism very different than the surrounding ground. However, it needs an instrument with at least a sensitivity of 1nT or better with a data logging capability.

Willy