if it's not ree..., page-3

Electric conductivity is very important. I originally thought this type of survey would primarily detect metals, but some more research indicates that even water saturation and salinity in the rockbed can alter the signature in certain ways.

And it's still a "2D" picture of a "3D" reality... so I'd have to think it may be very hard to distinguish between dense quantities of a material with a low electromagnetic signature and sparse quantities of a material with high electromagnetic signature.

But I am not qualified to say what kind of distinctions this type of survey can exactly make. For it to be any use, I'd have to assume they can tell the difference between a salty aquifer formation and metallic elements or compounds, but I am just not sure whether that is the case or not. It could be that they are just having an educated guess based on what the picture looks like and what they know about the general geological area.

Anyone with specific knowledge of how this works should feel free to step up and give us an overview of the basics.