Ben,

I agree with Jim.  Based upon your description of the site, you would  
need someone with great Kung-fu on the radar unit to see post-in- 
ground architecture.  I would also recommend using a metal detector  
survey before getting a magnotometer out there.

Of course, for $15, you could also try "Plant Stress Detection  
Glasses" with purple len filters.  These are designed for  
greenskeepers to see stressed turf in the fairway, but I think they  
just might work to show patterns of stressed plants that could help  
you see your footprints or foundations.  They might not work at all,  
given the plowing, but for $15, it's worth a shot.
http://www.safetyglassesusa.com/cl01v0id.html?SSAID=216026
For those do-it-yourself types out there, you can get directions on  
how to build your own here:
http://mvh.sr.unh.edu/mvhtools/psd_filters.htm

I ordered a pair from Forestry Suppliers earlier this year and I'm  
waiting until next spring to look some sites up here as the plants go  
through their growth cycles.

Cheers
Tim


On Sep 13, 2010, at 10:17 PM, Jim wrote:

> Ben,
>
> I would strongly recommend not spending money on a GPR survey before  
> doing a
> thorough metal detection survey.  GPR is expensive and, if not used in
> conjunction with another subsurface technique such as magnetometry  
> or soils
> resistivity may prove to be almost useless.
>
> Suggest gridding the site in 20 ft or similar grid units and going  
> over each
> unit at least twice using experienced detectorists with good  
> equipment.  The
> frequency of hits within each grid unit can be converted to a  
> gradient map
> that will show the relative distribution of metal material. This can  
> be used
> as a guide for further work whether it be a GPR survey or testing.
>
> I would not excavate hits from deeper that the plow zone (roughly 12  
> inches)
> so as not to disturb any intact buried deposits.
>
> Good luck
>
> Jim
>
> James J. D'Angelo, RPA. Ph.D.
> President & Site Archaeologist
>
>
>
> The Fort Daniel Foundation, Inc.
> Phone: 770-513-1576
> Cell: 404-580-2079
> Email: [log in to unmask]
> Visit us at: www.thefortdanielfoundation.org
>
> -----Original Message-----
> From: HISTORICAL ARCHAEOLOGY [mailto:[log in to unmask]] On Behalf Of  
> Benjamin
> Carter
> Sent: Monday, September 13, 2010 9:36 PM
> To: [log in to unmask]
> Subject: Renting GPR or Magnetometer.
>
>  All,
>
> I am in the process of studying a historic site (c. 1750) in eastern  
> PA.
> Based upon historic documents we have a good idea of the location of  
> the
> site and part of it falls within an open field. I have been over the
> site multiple times and there are very few hints as to where within  
> that
> field the site may be. There may have been one structure that had a
> stone foundation, but that may have been removed historically. There
> were probably approximately 35-50 other 'houses' that did not have  
> stone
> foundations. I want to try an relocate these structures based upon  
> their
> post-holes, trenches and artifacts, especially nails. At least one of
> the structures was burned so the nails should be distributed around  
> that
> foundation. These has been some historic disturbance at the site,  
> but I
> don't believe that structures were buried, but they were likely  
> plowed.
>
> I am trying to figure out the best way to relocate the site more
> precisely. I would love to use either GPR or Magnetometry, but the
> equipment can be extremely pricey and I have a fairly limited budget.
> There are also a myriad of variations that I could potentially use  
> and I
> am having a difficult time determining which would be the best.
>
> Does anyone have suggestions? Are there inexpensive GPR, etc.  
> equipment
> that I could rent? I am considering using metal detectors in the
> organized fashion laid out in previous posts to this list serve.  That
> seems more affordable and I may know a couple of people who have them
> and, hopefully, would help out. Unfortunately, that doesn't give me a
> great map like you can get from GPR. It is also limited because it  
> gives
> little information about the item that has been detected.
>
> I greatly appreciate any and all assistance.
>
> Cheers,
> Ben Carter