Ground Penetrating Radar (GPR)

[augusthog]

Been researching GPR's lately. Wondering if they can find abnormalities in hard rock, like pockets or small seams. I know they are pricey, but 1 good find would pay for it.
Anyone have a used one for sale or has anyone ever used one?
Thanks in advance!

 

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[Tom_in_CA]

Not sure about abnormalities like rocks or whatever, but as for coins, they are pretty useless. The smallest pixel size is something like 1" across, at the absolute most refined. And as such, is therefore useless for most detecting. I mean, every thing like coins, rings, tabs, nails, etc.... would all be .... doh .... just one pixel Even something you might THINK would be shape-revealing (like a horseshoe, for instance), are still nothing but a messy blotch of pixels.

 

[Frankn]

From what I have read about the units, they basicly show variations in density of the ground. This is a good indication that some ground has been disturbed such as digging and refilling. As far as solid rocks, It would show voids. It is not a picture , but a graphic representation expressed in line layers. Yes as Tom said, the resolution leaves a lot to be desired. Frank...

 

[Red James Cash]

If youre looking for gas pockets,caves, basically the answer is yes.

 

[Alan406]

Augusthog,

I just posted the following comments in another thread, but I think they may be applicable here too...

The effectiveness of ground penetrating radar (GPR) is dependent on numerous factors, including:

1. The center frequency of the GPR antenna.

2. The electrical properties of both the target you are trying to find and the surrounding material you are 'looking' through.

3. The size, orientation, and depth of bury of the target.

I've used GPR to find fractures in bedrock under 'good conditions'. Essentially, the soil over the bedrock was sandy, not clay-rich; the bedrock was a very competent (i.e., not weathered, generally consistent throughout its depth) granitic intrusion; and the fractures had been secondarily-enriched with mineralization. Very nice conditions for this type of geophysical method... and unfortunately, not very common...

In fact, I wasn't doing the GPR survey to find those mineralized fractures. I was actually using it to look for abandoned mine workings in the area.

Most of the time, I do not detect fractures in bedrock when I'm using GPR. There needs to be an electrical contrast between the host rock and the fracture in order to obtain a GPR reflection. Also, like I state above, there are numerous factors that play into detecting any target with GPR. So, I would highly suggest you rent a GPR to do a test run on your search area before you ever decide to purchase such an expensive instrument.

Just so you know, I'm a licensed engineer/geophysicist with over 20 years experience using GPR to find buried objects, map geology, detect and map caverns/former mine workings, and determine other subsurface conditions. I've been a silent observer of the TreasureNet forums for several years, and finally decided to sign up back in 2010. I enjoy treasure hunting as my hobby, and generally swing a metal detector to relax... so, that's why I've not posted much around here before...

However, I've just noticed a few posts about GPR and thought I should speak up.

Just thought my input may help,

- Alan406

 

[bigfoot1]

thx for your insights...