Barb,
Thanks for posting a positive message to Linda. I'm interested in situations in which OH has worked for folks. I'm not opposed to the technology, just not sure of how to evaluate the results I've seen so far. Our experimental results with temperature and depth (and in or out of shade) were disconcerting so I tend to be skeptical.
Thanks again,

Jeff

Jeffrey L. Boyer, RPA
Supervisory Archaeologist/Project Director
Office of Archaeological Studies, Museum of New Mexico

  *   The Center for New Mexico Archaeology
  *   PO Box 2087
  *   Santa Fe, New Mexico 87504
  *   tel: 505.476.4426
  *   e-mail: [log in to unmask]

"There comes a time in every rightly-constructed boy's life when he has a raging desire to go somewhere and dig for hidden treasure."  -- Mark Twain, The Adventures of Tom Sawyer


________________________________________
From: HISTORICAL ARCHAEOLOGY [[log in to unmask]] on behalf of Barbara Voss [[log in to unmask]]
Sent: Wednesday, April 09, 2014 12:37 PM
To: [log in to unmask]
Subject: Re: Obsidian hydration on historic sites

Hi Linda,

One benefit of obsidian hydration for colonial-era deposits is that it
allows us to answer questions of lithic recycling and scavanging. For
example, if multiple dates (prehistoric and historic) are indicated on
different flake scars that may indicate that mission residents were
obtaining older lithic tools and flakes for new uses. We have found several
examples of this at the Presidio of San Francisco.

In the SF Bay area, colonization profoundly disrupted obsidian trade,
changing the sources that were available to local Native Californians. I
would subdivide your assemblage according to source, and then consult with
your obsidian specialist about appropriate sampling for each source. We have
worked with Origer & Assoc. on colonial-era assemblages with great results.

--Barb

-----------------------------------------------
Barbara L. Voss, Associate Professor
Department of Anthropology
450 Serra Mall, Bldg. 50, Main Quad
Stanford University
Stanford CA 94305-2034
[log in to unmask]


-----Original Message-----
From: HISTORICAL ARCHAEOLOGY [mailto:[log in to unmask]] On Behalf Of Barbour,
Matthew, DCA
Sent: Wednesday, April 09, 2014 11:22 AM
To: [log in to unmask]
Subject: Re: Obsidian hydration on historic sites

Jemez Historic Site includes the remains of at least one and possible two
Spanish missions. Also located in the Jemez Mountains, we got a ton of
obsidian. There hasn't been major excavations out at the site since the
1970s (maybe 60s) and a little in the early 2000s. However, in both cases,
no one bothered with obsidian hydration. I am not saying it is not
worthwhile, but if your emphasis is on chronometrics, dendro is going to be
a better bet and in our case there were enough diagnostic ceramics to parse
out what dated to when for the most part. All this being said, I do not
think I have ever used obsidian hydration to date a site. I am no expert. If
it works when dealing with such a refined date range, I would be surprised,
but please let me know if you have success.

Matt



Matthew J. Barbour
Site Manager

Jemez Historic Site
PO Box 143
Jemez Springs, NM 87025
email: [log in to unmask]
office: 575.829.3530
cell: 505.220.3270

________________________________________
From: HISTORICAL ARCHAEOLOGY [[log in to unmask]] on behalf of Linda Hylkema
[[log in to unmask]]
Sent: Wednesday, April 09, 2014 11:59 AM
To: [log in to unmask]
Subject: Obsidian hydration on historic sites

Hi all,

We are starting the analysis phase of a major excavation on a California
mission site (ca 1780-1840's). We have a number of pieces of obsidian
(debitage and formal artifacts). My consultants are proposing hydration on
25 pieces from the assemblage. We have already sourced all of it (except
pieces that are too small) with our XRF. Sources are the same as what has
been traditionally found in pre-contact sites of the region. My questions
are:

1. What would be gained from dating obsidian from a a site with such a tight
temporal margin, and such a recent one at that? Establishing calibration
markers for comparison for other late period sites??

2. If determined to be a relevant task, would would be a statistically valid
sample from an assemblage of about 200 pieces that includes 20 projectiles?
I know that's a hard, if not impossible, question without knowing more about
my site, but any insight would be appreciated. If you'd like more details
about the site to answer my questions, please feel free to contact me
off-line. It's a rich site, and we excavated fifty-six discrete pit features
full of mission trash, which is where all the obsidian is from.

At this point, I'm not convinced that it will add substantially to our
interpretation of the site.

ANY insight is appreciated.

Linda


*Linda Hylkema*
*Cultural Resources Manager, Santa Clara University*
W: *408-554-4513* | C: *408-219-5748* | F: *408-551-1709* | 500 El Camino
Real, Santa Clara, CA 95053