Barbara

I want your email program ... it appears to have artificial intelligence!  Your email, about using ground-probing radar (GPR) required similar techniques to discover the content!  At least on my email program anyway.

Seriously though, I've never personally used GPR.  Have heard lots about its use in the UK and Australia.  Here goes with the third-hand information!!!!

GPR needs very good operators.  Interpretation is the key.  It works best on larger substructures, as the resolution suffers with things down at the scale of hidden fixings.  That is not to say it is impossible.  I was talking to somebody from English Heritage recently, and they used GPR to find the steel fixings in a stone clad building (so that they could then do cathodic protection amongst other things).

I've also seen articles / papers on the use of the technique to determine the construction sequence of old masonry bridges.

Requires a certain amount of opening up to interpret the findings, but if you have larger areas you need to survey, definitely has some potential in my opinion.  Just be healthily sceptical about the claims of the providers of GPR, and you should be able to find lots of secrets!!!

Cheers

david

PS  Imagine how much easier those outhouse documentation jobs would be if we all had ground-probing radar!!