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