All,

Thank you for the many responses. They have all been very useful.

Let me address some of your questions. I have used aerial photos from 
the 1930s, 1950s, 1960s and Google Earth images from 1992 until now. 
There is relatively little evidence from grass growth, etc. of where the 
structures may have been. I even took some current aerial photos using 
kite aerial photography, but there are no patterns present that would 
suggest sub-surface structures. One weekend, I did rent an inexpensive 
metal detector (Garrett ACE 250) and did a VERY informal and 
non-systematic survey of the site. I found that certain sections of the 
site had greater concentrations of "hits". These tended to be in the 
location where I suspected they would be based upon historic maps and 
where we currently have permission from the landowner to excavate.

It looks like a GPR/magnetometer survey is essentially out of the 
question at this point.

I am going to attempt to run a systematic metal detector survey at this 
point along with some test excavations.

What do people use for 'flagging' hits with the metal detector? These 
need to be non-metallic, correct? Where can I get such a thing (perhaps 
in multiple colors)?

Cheers,
Ben



On 9/14/2010 12:00 PM, Richard Lundin wrote:
> Ben:
>
> I, heartily, agree that metal detecting is the FIRST thing to try. I use
> relatively inexpensive units (around $125) available at most WALMART or Big
> 5 stores that are VLF systems with a "Bounty Hunter" technology.  I run my
> surveys, first, with no discrimination and pin flag all anomalies with
> YELLOW pin flags, then, AFTER I have shot in all of the anomalies with an
> EDM or plane table and alidade (being old fashioned and wanting a map I can
> look at). I, then, run the entire area again with FULL discrimination and
> place RED pin flags on the non-ferrous anomalies.  Patterns will then
> emerge.  I, then, run a Class 1 (orientation) survey that involves a N-S and
> an E-W transect that cuts the patterns.  Using this data, I set my grids and
> do radiometric, VLF-EM and moisture\pH surveys (very cheap) along a series
> of N-S or E-W Class 2 lines spaced 5 meters apart and with 1 meter stations
> on line, taking VLF-EM, radiometric and moisture\pH data as I go plotting
> all the data on the plane table map and in profile.
>
> IF the metal detector data shows extensive areas with +3 YELLOW flags per
> square meter (high ferrous content) I go, immediately, to resistivity,
> VLF-EM, radiometric or portable X-Ray fluorescence (pXRF) methods which are
> relatively cheap and easy to do AND any magnetometer data will be nearly
> useless.  If NOT, then I go with a total field magnetic survey in a Class 2
> format as above with an older magnetometer that has +/- 1 gamma sensitivity,
> is easier to obtain, cheaper to rent and will give you just as good data in
> the iron-rich environment of a typical historic era site.
>
> I, then, plot the Class 2 data in profile while integrating the nearby metal
> detector anomalies as symbols on the profile, the radiometrics as an
> indicator of K levels in the soil and the pH\moisture data as a possible
> cause of resistivity\conductivity anomalies. Following up on the Class 2
> surveys Class 3 (Grid) surveys with the Combined Survey format (CSF) metal
> detector, resistivity, radiometrics, VLF-EM, pXRF and pH\moisture data.
>
> As GPR is the most expensive to use and hardest to interpret, I use it
> sparingly in a Class 3 (Grid) survey (usually with a 1000 mhz) antenna over
> the areas of interest from the Class 2-3 CSF archaeogeophysical and
> archaeochemical (pXRF) anomalies.    I then use the 1000 mhz GPR data to
> image the anomalies in three dimensions.
>
> IF the site is vegetated, plant geochemistry MAY be very useful in defining
> activity areas.  With a limited budget, this can be done with the taking of
> plant samples (same species, grasses work well back east as we are finding
> from our work a Cahokia) at the same locations as taking soil pXRF readings,
> solar drying the plant materials to a powder and then running the powder by
> pXRF.
>
> As noted in previous posts, most of the geophysical equipment can be easily
> obtained for a weekend test program from university geosciences or material
> science departments, mining companies or engineering firms for the cost of a
> dinner and\or a few beers.  The pXRF equipment is now pretty readily
> available on loan\demonstration for short duration projects from companies
> such as OLYMPUS INNOV-X or THERMO Fisher Scientific NITON Analyzers and,
> sometimes, if you have a really newsworthy project, the GPR equipment can be
> supplied by MALA on a demonstration basis. Training on this equipment can
> come from the equipment manufacturers or the National Park Service has a
> great (and inexpensive) training course run on a yearly basis by Steve
> DeVore.
>
> As a minerals exploration geophysicist, geochemist and, NOW,
> archaeogeophysicist and archaeochemist with over 40 years doing this sort of
> work and NOW doing these sorts of studies to find (and avoid) hidden
> archaeological sites for our mineral industry and governmental clients, I
> know that this phased approach works for finding and defining areas of,
> even, very subtle traces of human activity that archaeologists often miss
> with surface surveys.
>
> If you have any questions on this approach or need to discuss YOUR project
> please feel free to call me at WRI's Sonora California Office number: (209)
> 532-3873. Alternately, you can look Dr. Claudia Brackett and myself up at
> the upcoming SHA Archaeochemical Workshop in Austin in January.
>
> Best of luck on YOUR project!
>
> Sincerely,
>
> Richard J. Lundin BA, MA, RPA, ISAP
> Consulting Historical Archaeologist&  Remote Sensing Specialist
> (Archaeogeophysics)
> Director, Wondjina Research Institute
>
> -----Original Message-----
> From: HISTORICAL ARCHAEOLOGY [mailto:[log in to unmask]] On Behalf Of Paul
> McLeod
> Sent: Monday, September 13, 2010 8:33 PM
> To: [log in to unmask]
> Subject: Re: Renting GPR or Magnetometer.
>
> Hi Ben- I used to work as a mineral exploration geophysicist, and from time
> to time while out in the field, I would sometimes offer my services to
> archaeologists for recon-level work just for fun.  I had free access to the
> geophysics equipment, so the only thing it cost me was a little bit of my
> time.  I found magnetometry worked great on some sites and worked hardly at
> all on others- The place you are most likely to find cheap to free
> geophysical equipment and/or services is university geophysics departments 
> You might find a student who is looking for a good project for a class or
> for a thesis who has access to the equipment who would work for free (or for
> beer).  Another possibility to investigate is the engineering contractors
> who do mineral exploration or environmental/geotechnical engineering.  Of
> course they charge lots of money for their services, but if you find a
> sympathetic worker who is interested in archaeology, you might be able to
>   work out a deal.
> Just some thoughts.   Paul
>
>
> --- On Mon, 9/13/10, Benjamin Carter<[log in to unmask]>  wrote:
>
>
> From: Benjamin Carter<[log in to unmask]>
> Subject: Renting GPR or Magnetometer.
> To: [log in to unmask]
> Date: Monday, September 13, 2010, 8:35 PM
>
>
> 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
>
>
>
>
>