Sunday, December 13, 2009

University of Arizona professor uses an SLR to examine paintings in the infrared

Charles M. Falco's inexpensive, modified digital SLR camera has thrilled art conservators with what it can do at infrared wavelengths.

By Lori Stiles, University Communications
December 4, 2009
[edited from article at University of Arizona news]

A scientist at the University of Arizona in Tucson has modified a commercial 8-megapixel digital SLR camera for infrared use, creating an inexpensive, portable new tool that even amateur photographers can use to quickly see through layers of paint in artwork to reveal drawings, defects or other features on the original canvas.

Conservators have been using infrared, or IR, cameras to examine and document artwork since the late 1960s. "But these cameras can cost upwards of $100,000, so the number of paintings studied by this technique has been extremely limited," said UA optical sciences and physics Professor Charles M. Falco.

‘The technique is based on the fact that many common pigments are partially transparent to infrared light, making it possible to use appropriate infrared sensors to capture important information from surfaces that are covered by layers of paint," he said.

Early last year, Falco – an experimental physicist who has been interested in photography and in art since childhood – had an idea that he thought might work

He realized that modern digital cameras use silicon sensors sensitive to the germane infrared wavelengths and that such cameras might be modified to capture high-resolution infrared photographs – or "IR reflectograms" – of works of art.

Falco bought a one-generation-old Canon 30D camera on eBay.

"If this didn't work, I would have been out the better part of $1,000. But I was willing to accept that," he said.

For about another $450, Falco converted the camera by removing the infrared-blocking filter and replacing it with a visible-blocking filter, thereby allowing only IR light to reach the camera's sensor. He also adjusted the electronics so that the autofocus feature automatically offsets the camera lens to bring infrared light into sharp focus.

Then he began visiting museums to photograph art.

In a little over a year, Falco has tested his system under a variety of conditions in a dozen museums on three continents, including the National Gallery of Art in Washington, D.C., the State Hermitage Museum in St. Petersburg, Russia, and the National Museum of Western Art in Toyko, Japan.

The first paintings Falco studied were in the Samuel H. Kress Collection at the University of Arizona Museum of Art. Among these works is a painting titled "The Man of Sorrows with Saints and Donors." It was painted by an unknown French artist, probably sometime between the years 1525 and 1550.

"My camera let me discover something about that painting that nobody knew existed - that there are guide lines under the paint that the artist used to create the pedestal in perfect perspective," Falco said. "These lines reveal that this Early Renaissance artist understood and based his drawing on the constructed laws of perspective."

Falco's converted camera, including its 35mm f/2 lens purchased for less than $250, cost about $2,000 total.

Editors of the "Review of Scientific Instruments" invited Falco to write a technical description of his high-resolution imaging instrument and published the paper as the cover story of their July 2009 issue. The paper, titled "High resolution digital camera for infrared reflectography" is published online.

Saturday, December 5, 2009

Annual NPS archeological prospection workshop

The National Park Service’s 2010 workshop on archaeological prospection techniques entitled Current Archaeological Prospection Advances for Non-Destructive Investigations in the 21st Century will be held May 24-28, 2010, at the Knife River Indian Villages National Historic Site near Stanton, North Dakota.
Photo: Rob Sternberg, Knife River Indian Villages

The field exercises will take place at the Knife River Indian Villages National Historic Site.  Lodging will be in the in the communities of Beulah, Hazen, and Riverdale, North Dakota. 

The park preserves the historic and archeological remnants of the culture and agricultural lifestyle of the Northern Plains Indians during the 18th and 19th centuries.  Co-sponsors for the workshop include the National Park Service and the State Historical Society of North Dakota.  This will be the twentieth year of the workshop dedicated to the use of geophysical, aerial photography, and other remote sensing methods as they apply to the identification, evaluation, conservation, and protection of archaeological resources across this Nation.  The workshop will present lectures on the theory of operation, methodology, processing, and interpretation with on-hands use of the equipment in the field.  There is a registration charge of $475.00.  Application forms are available on the Midwest Archeological Center’s web page

For further information, please contact Steven L. DeVore, Archeologist, National Park Service, Midwest Archeological Center, Federal Building, Room 474, 100 Centennial Mall North, Lincoln, Nebraska 68508-3873: tel: (402) 437-5392, ext. 141; fax: (402) 437-5098; email: steve_de_vore@nps.gov.

Tuesday, December 1, 2009

Archaeometric crisis in American archaeology?


Every several years, we see a cogent argument for the need for more archaeomety in archaeology.  A recent plea was made in the SAA Bulletin by David Killick, Professor in the Department of Anthropology at the University of Arizona, and Paul Goldberg, Professor in the Department of Archaeology at Boston University.  The article, entitled

A Quiet Crisis in American Archaeology

can be downloaded with the January 2009 issue of the SAS Bulletin.   You'll find this essay on page 6.  It focuses on issues of innovation, funding, eduction, and training. The poor showing of American archaeometry compared to the situation in Europe is lamented.

Photo: (a youthful?) David Killick
source: University of Arizona

Friday, November 27, 2009

Turkey and archaeometry


Since its foundation in 1956, Middle East Technical University in Ankara has been very involved in archaeology and archaeometric studies. This interest, which first existed independently in the departments of physics and chemistry, flourished with the Keban Dam Rescue Project (1968-1974). 

METU hosted the 29th International Symposium on Archaeometry in Ankara in 1994. (Sadly, that was one that I missed.)


METU initiated a Master's Program in Archaeometry as part of the Graduate School of Natural and Applied Sciences in 1990.  The main purpose of the program is to teach graduates how to solve archaeological problems through the application of  methods from the natural and applied sciences. The study and understanding of history have acquired a new dimension through this kind of collaboration between pure scientists and archaeologists.

And you thought this was going to be about Thanksgiving, didn't you?

Sunday, November 22, 2009

Archaeological geophysics short course; Australia

From our friend Ian Moffatt:

Just a quick reminder that an "Introduction to Archaeological Geophysics" short course is running on 10 December just before the Australian Archaeology conference being held at Flinders University.

There will be a basic introduction to geophysical techniques and their application to archaeological problems followed by a hands on session collecting, processing and interpreting data from a range of methods. You'll come away with a good understanding of which geophysical techniques might be able to help out with your archaeological projects and an informed basis for the interpretation of this data.

The course costs $150 for students, $220 for non-students and includes lunch, morning and afternoon tea and a range of Flinders merchandise. The course is followed by the complimentary AA conference welcome BBQ.

You can register for the course here.

Please don't hesitate to contact Ian via email (ian.moffat@flinders.edu.au) if you require for any further information about the course.

Wednesday, November 18, 2009

Ceramic ecology session at AAA


The annual CERAMIC ECOLOGY XXIII symposium -- From the Field and Laboratory: Current Research in Ceramic Studies -- is scheduled during the annual meeting of the American Anthropological Association, on Saturday, December 5, 2009, 1:00-5:00 pm in Grand Ballroom Salon III, Downtown Philadelphia Marriott, Philadelphia, Pennsylvania, USA.  
   
The session will deal with current field and laboratory ceramic research from both the Old and New Worlds -- work that that includes the disciplines of archaeology, ethnoarchaeology, ethnography, archaeometry, and materials science. 
 
Traditionally, the symposiasts have dinner after the session; to help with a head count please email Charles Kolb about interest in the dinner.

See our President Sandra López Varela and Bulletin contributor Charles Kolb during the session:

Program Number:      3-141
Session:     CERAMIC ECOLOGY XXIII: CURRENT RESEARCH ON CERAMICS 2009
Session Sponsor:     Archaeology Division
Session Date/Time:     Sat., 1:45 PM-5:30 PM
Organizer:     CHARLES KOLB (National Endowment Humanities)

Participants:    
1:45 PM:     INTRODUCTION: CHRISTOPHER POOL (University of Kentucky) 
2:00 PM:     JAMES SHEEHY (n/a) -- Potters, People, and Land in Bihar, India: a perspective from the 1961 Census of India 
2:15 PM:     RAHUL OKA (University of Notre Dame), CHAPURUKHA KUSIMBA (Field Museum, Chicago) -- Producing and Exporting “South Asian” Islamic Monochrome Glazed Wares: Import Substitution and Market Capture in the 16th and 17th centuries CE? 
2:30 PM:     TARA TETRAULT -- Tracing Variation in Vessel Manufacture and Cultural Identity through Ceramics in Ghana, West Africa 
2:45 PM:     JOHN ARTHUR (University of South Florida) -- Pottery and Caste Groups: Historical Archaeology of the Gamo Highlands of Southern Ethiopia 
3:00 PM:     JEROLYN MORRISON (n/a) -- Must Haves for the Minoan Kitchen, a Tripod Cooking Pot and a Cooking Dish 
3:15 PM:     MICHAEL SUGERMAN, JILL BIERLY (University of Massachusetts) -- Idalion: Ceramics and Identity at an Iron Age Border Town in Cyprus 
3:30 PM:     JAMES SKIBO -- Stone Boiling, Fire-Cracked Rock, and Nut Oil: Exploring the Origins of Pottery in the Upper Great Lakes 
3:45 PM:     BREAK 
4:00 PM:     ALEKSANDRA WIERUCKA (University of Gdansk, Poland) -- The Disappearing Art: the Ceramics of Quichua along the Napo River 
4:15 PM:     AMY HIRSHMAN (West Virginia University) -- Petrographic Analysis of Paste Variability in Tarascan Fine Ware Ceramics: a Preliminary Assessment 
4:30 PM:     SANDRA LOPEZ VARELA (U Autonoma Estado de Morelos) -- Institutional Imagining of Development: new inquiry field for ethnoarchaeology 
4:45 PM:     JIM WEIL (Science Museum of Minnesota), ANAYENSY HERRERA VILLALOBOS (Asesores Arqueologicos) -- Archaeological and Ethnohistorical Inferences Based on the Manufacture of Three Ceramic Pieces by Contemporary Artisans on Costa Rica's Nicoya Peninsula 
5:00 PM:     CHARLES KOLB (National Endowment Humanities) -- From the Field and Laboratory: Current Research in Ceramic Studies 
5:15 PM:     DISCUSSANT: CHRISTOPHER POOL (University of Kentucky)

Monday, November 16, 2009

American Anthropological Assocation annual meeting

108th AAA Annual Meeting - THE END/S OF ANTHROPOLOGY
December 2-6, 2009
Philadelphia Marriott Downtown
Philadelphia, PA



 
What is the relevance of anthropology in today's world?  Where does our discipline stand in the age of hyper-science and the genome; during an era in which ethnography – as a method and form of textured representation – is being mobilized with vigor and confidence by those working in other disciplinary formations; at a moment when the questions we're asking are also being answered by others in the humanities, social sciences, and media (and often with much more popular recognition)? Does anthropology still provide a unique contribution? What are its contemporary goals, and are they different from those of previous intellectual generations?

Sessions include:

NEW ANALYTICAL APPROACHES IN ARCHAEOLOGY
Session Sponsor:     Archaeology Division
Session Date/Time:     Sat., 10:15 AM-12:00 PM
Chair(s):     LAURA JUNKER (University of Illinois Chicago)

LAURA JUNKER (University of Illinois Chicago), EKATERINA KHRAMTSOVA (U of Illinois at Chicago) -- Ceramic Evidence for Variation in Feasting Patterns in Lowland and Upland Societies of the 15th-16th Centuries Philippines 

LINDSEY CLARK (Washington State University), ANDREW DUFF (Washington State University), ANDREW DUFF (Washington State University) -- Examining Social Interaction within a Chacoan Community Through Ceramic Stylistic Variation 

JAMES VANDERVEEN (Indiana University South Bend), DARRYL RICKETTS -- Embodying the Ancestors: The Symbolism of Cranial Deformation in Pre-Columbian Caribbean Societies 

SHANA WOLFF (Laramie County Community College) -- The Antimicrobial Effectiveness of Plants Traditionally Used by Plains Indians as Topical Antiseptic

Saturday, November 7, 2009

Paul Goldberg wins Pomerance Award for 2010

The Archaeological Institute of America has announced that Professor Paul Goldberg will receive the 2010 Pomerance Award for Scientific Contributions to Archaeology. The Science Award is one of the two greatest honors that the AIA confers. The Science Medal will be awarded at the awards ceremony during the AIA annual meeting in Anaheim, CA (January 6-9, 2010).

I met Paul during my first trip to Israel to collect archaeomagnetc samples in 1984.  Or maybe it was the second trip in 1986.  Who can remember any more?  Anyway, I have appreciated him as a colleague and friend ever since.

Congratulations, Paul!

Monday, November 2, 2009

Field geology session at the International Symposium on Archaeometry

I want to be sure you are aware of the session on


Field Archaeology (remote sensing and geophysical prospecting, sampling and field walking strategies, in situ observations of preservation, site monitoring)

to be held at the International Symposium on Archaeometry (http://isa2010.cas.usf.edu/) next May in Tampa.

This session is being co-organized by Luis Barba and myself (Rob Sternberg).

Please consider submitting an abstract. The deadline is 1 Dec. 2009.


Photo: Rob with student Ali planning out some magnetometer traverses at an Etruscan archaeological site.

Thursday, October 29, 2009

Archaeometry in the movies

Anyone see this? Any suggestions for other appearances of archaeometry in the movies?

Movie Review from the New York Times:

Opa! (2005)
October 16, 2009
Love and Archaeology

By NEIL GENZLINGER

Opa!, a sweet, nontaxing movie set in the gorgeous Greek Isles, has a bit of a black hole at its center named Matthew Modine. But the film’s female lead, Agni Scott, and some fine supporting players make this small film a pleasant if predictable diversion.

Mr. Modine plays an archaeologist named Eric who comes to Patmos in search of a particular religious relic that eluded his archaeologist father his whole career. Eric has something his father didn’t: a computer gizmo that enables him to find likely locations for buried treasures using satellite imagery.

Eric is supposed to be shy and awkward, but Mr. Modine makes him too bland to be interesting, which leaves you wondering why the lovely Ms. Scott’s character, Katerina, would fall for him. The vivacious Katerina owns a popular tavern, and when Eric pinpoints what he thinks is the location of the object he’s after — well, there’s a choice to be made.

Richard Griffiths does some nice work as an old-style archaeologist, conveying with just the occasional melancholy expression the wistfulness of an academic breed being swept aside by new methods.

Friday, October 23, 2009

Archaeological science vs. archaeology vs. anthropology


On my recent trip out west, I learned of two academic departments where the cultural anthropologists and archaeologists had split and formed separate departments.  I guess even the best of unions suffer after long relationships.  Kind of too bad, though, with all the fuss we make about using the natural sciences in the service of problems important to the social sciences. And, who gets the office furniture when it's all over?

Always interesting to look at the different situation in Europe, where there are entire departments of archaeology, sometimes with specialties in archaeological science.  I'm hoping to visit Bradford when I am in Europe this coming Spring.  Not only can you get an undergraduate degree in archaeology, but you can also specialize in archaeological science.  Pretty sweet.  I know from the majors in environmental science within my own department that those interdisciplinary majors can be tricky, but if done right with an eye for rigor, there is much to be gained.

What are some academic models or departments that you think make for good training for the archaeological sciences? Feel free to comment below.

Monday, October 19, 2009

Blood and guts and archaeometry- eBook available

Archaeological Science Under a Microscope
Studies in Residue and Ancient DNA Analysis in Honour of Thomas H. Loy
Terra Australis 30
Edited by Michael Haslam, Gail Robertson, Alison Crowther, Sue Nugent and Luke Kirkwood
ISBN 9781921536847 $55.00 (GST inclusive)
ISBN 9781921536854 (Online)
Published July 2009


These highly varied studies, spanning the world, demonstrate how much modern analyses of microscopic traces on artifacts are altering our perceptions of the past. Ranging from early humans to modern kings, from ancient Australian spears or Mayan pots to recent Maori cloaks, the contributions demonstrate how starches, raphides, hair, blood, feathers, resin and DNA have become essential elements in archaeology’s modern arsenal for reconstructing the daily, spiritual, and challenging aspects of ancient lives and for understanding human evolution. The book is a fitting tribute to Tom Loy, the pioneer of residue studies and gifted teacher who inspired and mentored these exciting projects.

Downloadable for free in pdf format.

Wednesday, October 14, 2009

Leonardo and forensics strike again

This time it is his fingerprints!

From CBC News:
A small picture of a young woman in profile owned by a Canadian collector may be a work by Leonardo da Vinci.


Art experts say there is strong evidence the picture is by Leonardo after finding a fingerprint on the Renaissance-era painting that matches another fingerprint found on his St Jerome in the Vatican.

The fingerprint was found by Peter Paul Biro, a Montreal-based forensic art expert, through multispectral analysis, which detects images unseen by the naked eye.

The hairstyle and robe worn by the young woman in the ink and chalk image is consistent with Milanese fashion of the late 15th century, experts say. Carbon dating also suggests the painting dates from the late 1400s, when Leonardo would have been painting.

Art Access & Research has put out a press release to highlight the important work performed on this project by its Director of Forensic Studies, Peter Paul Biro.
Art Access & Research Leonardo press release (pdf, 100KB).

Tuesday, October 13, 2009

SAA Fryxell Ward

Fryxell Award for 2011                       

The Society for American Archaeology Fryxell Award is presented in recognition for interdisciplinary excellence of a scientist who need not be an archaeologist, but whose research has contributed significantly to American archaeology. The award is made possible through the generosity of the family of the late Roald Fryxell, a geologist whose career exemplified the crucial role of multidisciplinary cooperation in archaeology. Nominees are evaluated on the breadth and depth of their research and its impact on American archaeology, the nominee’s role in increasing awareness of interdisciplinary studies in archaeology, and the nominee’s public and professional service to the community. The award cycles through zoological sciences, botanical sciences, earth sciences, physical sciences, and general interdisciplinary studies. The 2011 Fryxell Award will be in the area of zoological sciences (zooarchaeology image from Amarna Project). The award will be given at the SAA’s 76th Annual Meeting, 2011, in Sacramento, California. The award consists of an engraved medal, a certificate, an award citation read by the SAA president during the annual business meeting, and a half-day symposium at the Annual Meeting held in honor of the awardee.

Special requirements:

• Describe the nature, scope, and significance of the nominee’s contributions to American archaeology.
• Curriculum vitae.
• Support letters from other scholars are helpful. Four to six are suggested.

Deadline for all nomination materials: February 5, 2010

Contact: Virginia L. Butler; Portland State University; PO Box 751; Department of Anthropology; Portland, OR 97207-0751; ph: (503) 725-3303; fax: (503) 725-3905; e-mail: butlerv@pdx.edu

Thursday, October 8, 2009

"Remote sensing" for Leonardo with neutron beams

The New York Times reported this week on the search for a masterpiece of Da Vinci, The Battle of Anghiari, that is presumably "buried" beneath other frescoes in the Palazzo Vecchio, Florence.

One technique uses backscattered neutrons, the other uses emitted gamma rays in a version of neutron activation analysis.


An interview with Maurizio Seracini, the lead engineer, appeared in Wired.

There is also a scientific article out discussing preliminary tests:
Neutron back scattering for the search of the Battle of Anghiari

Monday, October 5, 2009

Shroud of Turin (further) debunked

From the Associated Press:
ROME — Scientists have reproduced the Shroud of Turin — revered as the cloth that covered Jesus in the tomb — and say the experiment proves the relic was man-made, a group of Italian debunkers claimed Monday.

The shroud bears the figure of a crucified man, complete with blood seeping out of nailed hands and feet, and believers say Christ's image was recorded on the linen fibers at the time of his resurrection.

Scientists have reproduced the shroud using materials and methods that were available in the 14th century, the Italian Committee for Checking Claims on the Paranormal said.

The group said in a statement this is further evidence the shroud is a medieval forgery. In 1988, scientists used radiocarbon dating to determine it was made in the 13th or 14th century.

But the dispute continued because experts couldn't explain how the faint brown discoloration was produced, imprinting on the cloth a negative image centuries before the invention of photography.

Many still believe that the shroud "has unexplainable characteristics that cannot be reproduced by human means," lead scientist Luigi Garlaschelli said in the statement. "The result obtained clearly indicates that this could be done with the use of inexpensive materials and with a quite simple procedure."

The research was funded by the debunking group and by an Italian organization of atheists and agnostics, he said.

Garlaschelli, a professor of chemistry at the University of Pavia, said in an interview with La Repubblica daily that his team used a linen woven with the same technique as the shroud and artificially aged by heating it in an oven and washing it with water.

The cloth was then placed on a student, who wore a mask to reproduce the face, and rubbed with red ochre, a well known pigment at the time. The entire process took a week, Repubblica said.

One of my graduate student mentors, Paul Damon, was involved in the radiocarbon dating.

In any case, the Shroud will be on public display next April-May, according to the official web site. It usually is shown only a couple of times each century. I'll be on sabbatical in Europe - I might just go!

Image from the official web site.

Sunday, September 27, 2009

Metal detecting, pro and con

Pro: As you've probably heard, you could find a magnificent Anglo-Saxon treasure trove!

Con: More likely, you are probably just wasting your time on the "world's worst hobby."

This is like playing the lottery (or, what used to be called the numbers before the state took it over). Probabilistically, it is a waste of time and money (why I don't play). But your chances of winning are finite (albeit slimmer than I have been for many years).

photo: www.fisherlab.com

Thursday, September 24, 2009

e-chonometry

http://edatingforher.com/images/ebook.png

The last two days have brought two junk comments about meeting women onto an earlier entry on pottery hydration chronometry. I think I know what keyword attracted those comments. Guess I will have to be more careful.

Psst ... don't click on the picture above; nothing will happen.

Saturday, September 19, 2009

NSF Archaeometry program - approaching deadline

Archaeometry Awards

Target date: October 31

The Archaeology Program recognizes three broad classes of archaeometric proposals: (1) proposals to support laboratories which provide archaeometric services; (2) proposals to develop and refine archaeometric techniques; (3) proposals to apply existing analytic techniques to specific bodies of archaeological materials. "Laboratory support" and "technique development" projects are included within the Archaeometry competition. "Technique application" proposals are best evaluated in a more strictly archaeological context and therefore should be submitted to the "senior" research competition.

More info at the program web site.

Sunday, September 13, 2009

Stream Time Team America

from http://www.pbs.org/opb/timeteam/sites/ftjames/diary_meg.php


I'm still catching up from my time away. One of the things I'd like to do is watch the episodes of Time Team America. But I can do that because they are streamable from PBS. Fort James, Range Creek, and Philadelphia - here I come.

Thursday, September 10, 2009

SAS presence online

Thanks to the efforts of SAS webmeisterin Destiny Crider and President Sandra López Varella, our web page and wiki have a revised look. Although works in progress, the web page will likely remain a more static repository of society information; the wiki will add more timely material in the way or conferences and job announcements, and also be more easily available to multiple authors for the lab descriptions; and of course the blog here will be used for whatever strikes my fancy, or that of other potential authors.

Check these things out, and let us know what you think.


http://wordplayblog.com/free-cartoons-for-your-blog/

Sunday, September 6, 2009

Bob DuBois, archaeomagnetist

I've been away for a bit: archaeomagnetic sampling and magnetic surveying at the Etruscan site of Poggio Colla in Italy; improving my field geophysics with folks at the Bayerisches Landesamt für Denkmalpflege in Munich; presenting a talk on magnetic properties of legacy sediments at the IAGA symposium in Sopron, Hungary; and along the way also enjoying the Venice Biennale and Budapest.

I learned yesterday that Robert DuBois, a founder of American archaeomagnetism, has passed away. An obituary from the Norman, OK, newspaper is here.

I never worked with Bob directly, but I learned how to collect samples from Jeff Eighmy, who had worked with Bob as an undergraduate, and I also learned much about archaeomag from Dan Wolfman, who had worked with Bob as a graduate student. I was able to visit Bob and his wife Jeanette once in Norman, and they were gracious hosts. Bob was an indefatigable collector of samples for a number of years. In my opinion, his data were never fully vetted in the peer review literature, and this was a loss. Nonetheless, Bob put archaeomag on the map as a viable chronometric dating method, and many of us owe him for that.

Tuesday, August 18, 2009

Archaeological Geophysics Down Under














Just a quick note to let you all know that the "Introductory Archaeological Geophysics" subject offered through the Department of Archaeology at Flinders University, Adelaide, Australia from 21 September to 2 October 2009 is open to external students as a short course.

This course is intended for archaeologists who want to gain practical experience using geophysical techniques and is taught through a combination of lectures and extensive "hands on" data collection, processing, interpretation and reporting. Teaching staff include Ian Moffat and Lynley Wallis with specialist contributions from a range of industry partners.

For more information please visit the subject website or contact Ian via email (ian.moffat@flinders.edu.au).

Monday, July 27, 2009

Sub Ground Imaging offers free geophysics

I'm away in Europe for 6 weeks, so you won't see quite so much of me here. At the moment, I'm doing archaeometry and magnetometry at the Poggio Colla Etruscan site near Florence.

But via the ISAP litserv, and speaking of geophysics, a nice message from Sub Ground Imaging in southern England(superfluous capitalizations removed):


If you are managing an educational or other non-profit archaeological project,
and are interested in our services, please feel free to contact us. We may very
well be both able and willing to assist you. We will consider donating our
geophysics services free of charge to worthy projects that benefit education or
further the knowledge of British Archaeology.

Why as a commercial concern would we do this?That is simple. We ourselves have a keen interest in archaeology and understand the importance of its contribution to the history of our country. We also understand the importance of state of the art techniques and resources being available to educational projects and to non-profit
archaeological groups and societies.If you feel your project could benefit from our assistance please drop us a line with a brief outline of your project. We will be pleased to help any project we feel to be both genuine, and worthy.

Sunday, July 12, 2009

North (by Northwest?)

I often realize I'm behind in my reading when I come across a big idea I've missed. The NY Times recently had a nice piece on the idea of Steve Lekson that Native American cultures of the Southwest were disposed to migrate in a north-south direction. My gut reaction is skepticism - and apparently I'm not the only skeptic. Seems like the number of locations are few, and given geologic and climatic limitations, perhaps it is not surprising that these sites are approximately aligned along cardinal directions. But I'll leave it to Southwestern archaeologists and archaeoastronomers to sort this one out.

Thursday, July 9, 2009

Welcome, Time Team America

I enjoyed watching the first episode of Time Team America on PBS last night. I've never seen the UK show on which it is based. The program has a nice web site, where you can stream last night's show. On yesterday's episode, the team was trying to find evidence for the European colonization of Roanoke Island, North Carolina.

The show started out with some magnetometry, showing the very Bartington instrument I had been checking out for a proposal yesterday, and Meg Watters, the team geophysicist, running gpr. Personally, I'd explain magnetometry a little differently, but why quibble (except for the fact that I am an academic, so a professional quibbler). The archaeologist at the site was Nick Lucketti, of the First Colony Foundation, whom I did a small archaeomagnetic job for seven years ago. I also met Eric Deetz, another member of the Time Team, on that same trip to the Jamestown area. The show recalled to me some criticism of the Time Team Program that these three-day site visits are not how archaeology works, and I can see that criticism. The finds were relatively slim, although, as Nick said, more European household artifacts than had been found for some years. Still, this seems like a good way to excite the public about the possibilities of archaeology, and the application of scientific methods.

Thursday, July 2, 2009

The Pope as radiocarbon dater

From Times Online
June 29, 2009

"Pope Benedict XVI said last night that bone fragments found inside the tomb of St Paul in Rome had been carbon dated for the first time, 'confirming the unanimous and uncontested tradition that they are the mortal remains of the Apostle Paul'.


"He said that archaeologists had inserted a probe into the white marble sarcophagus under the Basilica of St Paul's Outside the Walls which has been revered for centuries as the tomb of St Paul.

"The pontiff said: 'Small fragments of bone were carbon dated by experts who knew nothing about their provenance and results showed they were from someone who lived between the 1st and 2nd century. This seems to confirm the unanimous and uncontested tradition that these are the mortal remains of Paul the Apostle.'"


From me: Is this the perfect intersection of science and faith? Or is there any chance this could be the bone of a commoner from the first century CE?

Sunday, June 28, 2009

Handheld xrf and archaeology

I'll have a unit on loan from Bruker this summer to try on ceramics and maybe soils at the Etruscan site of Poggio Colla where I've been working. Cool - thanks, Bruker!

Here's what another vendor, Niton, has to see about the possibilities of handheld xrf:

With new advancements in technology, archaeometry – or the collection of quantitative data from archaeological samples – is quickly becoming one of the most trusted methods in archaeological study. As the longtime industry leader in portable XRF analysis, Thermo Fisher Scientific is uniquely capable of providing handheld nondestructive testing solutions for art and artifacts in the field, in the lab, or on the museum wall.
NITON analyzers are ideal tools to aid in a variety of applications in art and archaeology, including:
Archaeological reconnaissance survey – obtain geochemical data instantaneously
Provenance – compare sources and artifacts, build databases, and much more
Restoration – match pigments and other materials for restoration quickly and accurately
Conservation – help identify how objects have been preserved in the past, and how to better conserve them for the future by looking at elemental composition data Cultural Resource Management – identify areas of historic human activity quickly and easily
NAGPRA Compliance – ensure that traces of toxic preservatives have been removed from artifacts prior to repatriation
Dating – glean important clues to the age of petroglyphs, alloys, and other materials through elemental analysis
Authentication – help authenticate a variety of art and artifacts using elemental data

Any success stories or warnings from my many readers?

Thursday, June 18, 2009

NSF Archaeometry grant to Cal State Long Beach


Carl Lipo's blog, Evolution Beach, reports on success at landing a grant from the NSF Archaeometry program.

This proposal, submitted by Hector Neff, Greg Holk (Geology) and Lipo provides funding for instrument upgrades, student support, and collaborative research support. The funding includes:


  • A Bruker Portable XRF spectrometer for chemical analysis.

  • A Costech ECS 4010 CHNSO Analyzer for isotopic analysis.

  • Subsidized research for collaborative archaeological projects. To be eligible for the subsidized rate, researchers will have to submit a CV and 3 – 5 page miniproposal describing the project and sampling design.

  • Visiting research program to support those who want to come to CSULB to conduct research involving highly innovative applications of LA-TOF-ICP-MS, and projects that innovatively use the isotope-rate mass spectrometer, the XRF or combine LA-TOF-ICP-MS with SEM/EDX/WDX.
Congratulations, Carl and colleagues! You've earned the respect of Prospector Pete.

Saturday, June 13, 2009

Australian archaeometry book online

Good deal. The full text of:

New Directions in Archaeological Science
Terra Australis
Edited by Andrew Fairbairn, Sue O’Connor and Ben Marwick
ISBN 9781921536489 $49.50
ISBN 9781921536496 (Online)
Published February 2009

is available online.

Archaeological Science meetings will have a personality of their own depending on the focus of the host archaeological fraternity itself. The 8th Australasian Archaeometry meeting follows this pattern but underlying the regional emphasis is the continuing concern for the processes of change in the landscape that simultaneously effect and illuminate the archaeological record. These are universal themes for any archaeological research with the increasing employment of science-based studies proving to be a key to understanding the place of humans as subjects and agents of change over time.

This collection of refereed papers covers the thematic fields of geoarchaeology, archaeobotany, materials analysis and chronometry, with particular emphasis on the first two. The editors Andrew Fairbairn, Sue O’Connor and Ben Marwick outline the special value of these contributions in the introduction. The international nature of archaeological science will mean that the advances set out in these papers will find a receptive audience among many archaeologists elsewhere. There is no doubt that the story that Australasian archaeology has to tell has been copiously enriched by incorporating a widening net of advanced science-based studies. This has brought attention to the nature of the environment as a human artefact, a fact now more widely appreciated, and archaeology deals with these artefacts, among others, in this way in this publication.

Thursday, June 11, 2009

NERC SBA

The National Environment Research Council of the UK used to publish a Science-Based Archaeology Newsletter. I have some old issues on my bookshelf. The NERC web pages still includes Science-based archaeology, although my casual perusal of the site doesn't easily reveal the scope of this endeavor. Sebastian Payne used to be the co-ordinator for the Science-Based Archaeology Newsletter, and he still writes columns for British Archaeology, which you can search for at the website of that magazine. See, for example, his recent article on forensic archaeology.

Monday, June 8, 2009

Archaeological Geology at GSA, Portland

The annual meeting of the Geological Society of America will be held in Portland, Oregon, 18-21 October, 2009.

Abstracts for contributions to the technical sessions are due August 11.

From the website of the Geological Society of America:

Sessions where Discipline Category = Archaeological Geology

T12. Holocene Alluvial Records: New Investigations of Archives of Millennial Change
GSA Quaternary Geology and Geomorphology Division
Tammy Rittenour, Joel Pederson
This session provides a venue for reporting new approaches and records regarding Holocene fluvial archives of millennial-scale and shorter-term climate response. Papers may include aspects of fluvial geomorphology, cosmogenic sediment yield, paleoflood hydrology, geoarchaeology, and geochronology.
Geomorphology; Quaternary Geology; Archaeological Geology
Submit an abstract to this session
T69. Ground-Penetrating Radar (GPR-Applications for Solving Stratigraphic and Geoarchaeological Problems
Kelsey S. Bitting
Applications of ground-penetrating radar (GPR-to near-surface stratigraphic and geoarchaeological problems are wide ranging, but GPR remains under utilized. This session will bring attention to this technology and provide an opportunity to showcase unique and innovative methodologies.
Stratigraphy; Geophysics/Tectonophysics/Seismology; Archaeological Geology
Submit an abstract to this session
T131. Ancient Coastal and Subsea Sites: New Findings and Problems
GSA Archaeological Geology Division; Smithsonian Institution
Jean-Daniel Stanley , Daniel F. Belknap
The session focuses on ancient land sites and former anthropogenic features now submerged off world coasts, a topic directly applicable for archaeologists working offshore, sea-level change specialists and managers formulating protections measures for vulnerable coastlines.
Archaeological Geology
Submit an abstract to this session
T153. Geoarchaeology and Late Quaternary Landscapes of North American River Valleys
GSA Archaeological Geology Division; GSA Quaternary Geology and Geomorphology Division
Todd Grote, Lara Homsey
This session will focus on recent interdisciplinary investigations of North American river valleys occurring from the landscape to site-specific scale. Submissions should contribute to understanding the archaeological record and late Quaternary lowland landscapes.
Archaeological Geology; Geomorphology; Quaternary Geology
Submit an abstract to this session
T154. Geoarchaeology, Reconstructions of Paleoenvironments and Past Human- Environment Interactions
GSA Archaeological Geology Division; GSA Quaternary Geology and Geomorphology Division; GSA Sedimentary Geology Division; Paleontological Society
Kathleen Nicoll, Catherine Yansa
Analysis of sediment and fossil records inform interpretations of cultural activity and Late Neogene-Quaternary environments. This session welcomes interdisciplinary papers on geoarchaeology and allied methodologies that reconstruct past landscapes, environments, and the human footprint on natural systems.
Archaeological Geology; Geomorphology; Quaternary Geology
Submit an abstract to this session
T155. Geochemical Geoarchaeology: Artifacts and Contexts
GSA Archaeological Geology Division
Katherine A. Adelsberger, Cynthia M. Fadem
Geochemical methods increasingly provide the critical tools for understanding paleoenvironments, site formation processes, and human behavioral decisions. This session will highlight the variety of geochemical methods used in geoarchaeology across cultural and temporal boundaries.
Archaeological Geology; Geochemistry; Quaternary Geology
Submit an abstract to this session
T156. New Advances in the Theory and Application of Luminescent and ESR Dating
GSA Archaeological Geology Division; GSA Quaternary Geology and Geomorphology Division, GSA Structural Geology and Tectonics Division, Paleontological Society, GSA Structure Geology and Tectonics Division
Bonnie A.B. Blackwell, Joel Blickstein
This session will hightlight new theoretical developments and their applications within geology, paleontology, and archaeology for the thermoluminescent, optically stimulated luminescent, and ESR dating methods, including new applications for dating barnacles, foraminifera, and sedimentary deposits.
Archaeological Geology; Quaternary Geology; Paleontology, Biogeography/Biostratigraphy
Submit an abstract to this session
T157. Obsidian from Magma to Artifact: Geological and Archaeological Perspectives
GSA Archaeological Geology Division; GSA Quaternary Geology and Geomorphology Division; Geochemical Society
Ellery Frahm, Joshua Feinberg
This session brings together archaeologists and geoscientists from diverse fields -- geochemistry, igneous petrology, volcanology, geomorphology, and more -- to present on the topic of obsidian research, from magma formation and eruption to dating and sourcing artifacts.
Archaeological Geology; Petrology, Igneous; Volcanology
Submit an abstract to this session

Field trips related to archaeology:
405. Geology and Geo-Archaeology of Hells Canyon, Oregon and Idaho
Wed.-Sat. 14-17 Oct. US$850 (B, L, D, R, 3ON).
Cosponsored by Oregon Paleo Lands Institute.
Leader: Ellen M. Bishop, Oregon Paleo Lands Institute.
This adventurous trip explores Hells Canyon—North America’s deepest gorge—jet-boating through Class 4 rapids, with three days in a rugged, legendary landscape. Hells Canyon marks a dominant Pacific Northwest (PNW) suture between North America and accreted terranes. The canyon offers an extensive record of Native Northwest cultures dating to nearly 11,000 years ago, where geology and Native history intersect. Geology emphasizes the growth of the PNW cordillera and the evolution of understanding active margin accretionary processes. Archeology emphasizes Sahaptian and Numic sites in one of North America’s most harsh yet bountiful areas, along with cultural effects of climate shifts, and Nez Perce/Lewis & Clark sites. Schedule: Day 1: Travel to Clarkston, Washington, USA; Day 2: Jet boat into Hells Canyon—Kirkwood area, Cougar Bar, with overnight at Copper Creek Lodge; Day 3: Explore Deep Creek and High Bar with overnight at Copper Creek Lodge; Day 4: Explore Eureka Bar, then return to Clarkston and on to Portland with late arrival.
418. Archaeology and Geomorphology of the Oregon Coastal Zone
Fri.–Sat., 16–17 Oct. US$225 (L, R, 1ON).
Cosponsored by GSA’s Archaeological Geology Division.
Leaders: Loren Davis, Oregon State University; Steve Jenevein; Jay Noller.
The Pacific Corridor for an-American transhumanance is focus of this field trip along the central coastal zone of Oregon. Archaeology will be demonstrated and discussed in the context of paleoenvironmental interpretation of several complex sections involving marine terrace cover sediments, coastal eolian dunes, Coast Range debris flows, estuarine and fluvial deposits, ghost forests, and soils. The chronology of events sealing archaeological deposits, including floods, slope failures, and tsunamis will be presented, and evidence supporting the current understanding of the Coastal Corridor will be discussed.

Thursday, June 4, 2009

Magnetic properties abstracts from AGU

The last few abstracts from these two session on geophysics and archaeology, looking at magnetic properties at two type of archaeological materials.

The image is unrelated, other than it is a cool representation of magnetic properties of thin films.

GP11I-03

Magnetic Susceptibility of Ancient and Modern Potsherds Using a Fast, Cheap and Portable Probe
Glover, P W (paglover@ggl.ulaval.ca), Université, Département de géologie et de génie géologique, Québec, QC G1V 0A6, Canada

It has been estimated that there exist over 100 million ancient potsherds in various collections worldwide, many of which have never been studied and for which the provenance is ambiguous or unknown. Indeed, many collections are extremely badly catalogued or completely mixed-up. We have been using a novel portable probe to measure the magnetic susceptibility and electrical conductivity of potsherds in the hope that this fast, cheap and portable measurement can provide data that will help to sort similar looking potsherds into sets in a manner which may help to define their provenance. The probe, which resembles a firearm, uses the Hall effect to make a non-destructive measurement on the potsherd. The probe is attached to an Dell Axim X51 PDA, which runs software that allows the measurement to be carried out and logged. Each measurement, which is made by pressing a button on the gun, takes only a few seconds. We have made measurements on three suites of ancient potsherds as well as a suite of modern potsherds that were created by using a garden centre and a hammer! In each case a set of 5 stacked measurements were taken on the inside and outside faces of the potsherd in two perpendicular directions. Potsherds which were either (i) so flat that the inside and outside could not be distinguished, (ii) so curved (radius of curvature less than 5 cm) that the probe tip could not approach the surface sufficiently closely, or (iii) smaller than the probe tip, were excluded from the suite of measurements. Each suite contained over 50 measureable potsherds. All measurements were completed within one day. In this pilot study we found that (1) each suite was represented by a normal distribution of magnetic susceptibility values, (2) the four different suites could be distinguished statistically on the basis of their magnetic susceptibility measurements, but (3) the distinction was not sufficiently powerful to separate all potsherds (i.e., there was a significant overlap of the susceptibility distributions). This seems to confirm that the method may be used to give additional information that can be used to help to provenance a potsherd, but the susceptibility measurement is not sufficient on its own. In addition, we found that (4) the electrical conductivity measurements depended upon the local conditions (mainly humidity) and was of no use in distinguishing between suites of potsherds. However, most interestingly, we found that (5) there is a statistically significant difference between the magnetic susceptibility measured on the inside face and that measured on the outside face for all three ancient suites of potsherd, but not for the modern potsherds. The reason for this is not currently known. One hypothesis is that the difference is due to the manufacturing style. Further studies are being planned to extend our database.
http://www.ggl.ulaval.ca/personnel/paglover/Home.htm


GP11I-04
Magnetic Fingerprinting of Central Mediterranean Obsidian Source Groups
Weaver, I (isaacweaver@alumni.fandm.edu), Department of Earth and Environment, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, United States
Sternberg, R (rob.sternberg@fandm.edu), Department of Earth and Environment, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, United States
Tykot, R H (rtykot@cas.usf.edu), Department of Anthropology, University of South Florida, 4202 East Fowler Avenue, SOC 107, Tampa, FL 33620-8100, United States

The Central Mediterranean islands of Lipari, Palmarola, Pantelleria, and Sardinia are known to be the only sources of obsidian in that region (Tykot, 2002). The obsidian on each source island has a unique chemical composition (i.e., a fingerprint) that has allowed Tykot (2002) to provenance Neolithic obsidian artifacts from archaeological sites throughout the Central Mediterranean to these four sources. Thus, Tykot (2002) revealed material distribution patterns otherwise inaccessible to archaeologists. An exploratory study by McDougall et al. (1983) demonstrated the potential use of magnetic properties to distinguish Central Mediterranean obsidians. If each obsidian source group has a unique magnetic fingerprint, magnetic provenancing might serve as a quick, inexpensive, and non-destructive alternative to chemical provenancing. Our research continues the work started by McDougall et al.; we set out to characterize the Central Mediterranean obsidians and search for magnetic fingerprints that distinguish them. Our preliminary study of the magnetic properties of 30 geologic obsidian specimens from Sardinia A, B, and C subgroups and the three other Central Mediterranean island sources suggests that each source has a unique combination of magnetic properties that could allow magnetic provenancing of archaeological obsidians. For example, the combination of natural remanent magnetization (NRM; median [med] = 2.46 x 10-4 Am2/kg, interquartile range [IQR] = 9.77 x 10-4 Am2/kg) and magnetic susceptibility (low field, low frequency magnetic susceptibility [χlflf]: med = 27.0 x 10-6 m3/kg, IQR = 75.9 x 10-6 m3/kg) seems to have good potential to discriminate the groups. However, statistical analysis shows that there is significant overlap in the confidence intervals of these variables, a limitation which appears to be partially imposed at this point by the small sample size. Discriminant analysis of several magnetic variables also shows potential to assist in classification (i.e., provenancing) of Central Mediterranean obsidians. We have obtained discriminant functions that correctly classify over 80% of the obsidian specimens in leave-one-out cross validations using as few as three log- transformed magnetic parameters: NRM, χlflf, and saturation isothermal remanent magnetization (SIRM; med = 7.59 x 10-3 Am2/kg, IQR = 2.85 x 10-2 Am2/kg). Backfield coercivity of remanence, median destructive field, percent frequency effect, and saturation coercivity seem to contribute the least to group discrimination, yet their effects are statistically significant. Even though initial tests of discriminant analysis look promising, it should be noted that the small sample sizes and relatively large number of variables used in the discriminant analyses violate the test's assumptions and may make the resulting discriminant functions unusable; this will be addressed in future research. The results from our preliminary study suggest that the Central Mediterranean sources of obsidian might have characteristic and distinguishable magnetic fingerprints. However, many more geologic obsidian specimens must be measured to define the ranges of the source groups' magnetic properties and to further test this hypothesis.

Sunday, May 31, 2009

Geophysical archaeoprospection abstracts from AGU

Here are the abstracts on geophsyical prospection at archaeological sites from the session I co-organized at the just completed American Geophysical Union Joint Assembly:

GP11I-02
Near Surface Magnetic Survey for Investigating the Cultural Relics in Suchon, Gongju, Korea
Islam, M R (mislam62@uwo.ca), Department of Earth Sciences, University of Western Ontario, 40,Summit Ave. Unit# 50, London, ON N6H4S3, Canada, et al.

A magnetic study by the FM256 Fluxgate Gradiometer was conducted in Suchon, Gongju to measure the vertical magnetic gradient of the Earth's magnetic field and to give further details of the shallow section. The region was divided into two separate areas. The first study area measured 40m by 20m while the second study area was 20m x 20m. Each was subsequently divided into four grids of dimension 20m by 10m and 10m by 10m respectively. Measurements of the vertical magnetic gradient were conducted through successive zigzag traverses. The sample-interval and the traverse-interval were set to specifically record small anomalies at a high resolution. A total of 3200 readings were measured at the first study area and 1600 at the second study area. The data have been downloaded, presented and processed through the Geoplot software to remove the spikes, grid discontinuities, and traverses stripes, and also to enhance the display and smooth the data using the Gaussian low-pass filtering techniques. The vertical gradient of the processed data over the second study area ranges from -34nT to + 21nT, while it ranges from -36nT to + 62nT at the first study area. The gradiometer results defined several positive and negative magnetic anomalies, which revealed the existence of several subsurface features of different shapes and sizes. A comparison between the processed magnetic images suggest that the subsurface features may include a room structure (e.g. hut), a cave-shaped stone chamber tomb, an accumulation of potteries and porcelains common in the Baekje period in the ancient Korean history. The biggest anomaly (3 m in diameter) may illuminate a quartzite tomb chamber. As a result, the study area has great archaeological interest.


GP22A-05 INVITED
The Donegal Sign Tree: A Local Legend Confirmed with Holographic Radar and 3-D Magnetics
Bechtel, T (bechtelt@sas.upenn.edu), Dept. of Earth & Environmental Science, University of Pennsylvania, Philadelphia, PA , United States, et al.

A tree at a crossroad in Historic Donegal, PA (founded 1722) bears unusual burls. Two are similar in size, and lie on opposite sides of the trunk at a height of six feet. Locals say that the tree engulfed an old road sign, and the geometry of the burls gives this appearance. However, the trunk between these two burls bears no welt where it sealed after swallowing the sign. In addition, there are other burls farther up the tree, which are not consistent with engulfed signs. Although the locals all know the legend of the swallowed sign, none ever actually saw the sign; not even an octogenarian who has lived at the crossroad his entire life, and recalls the tree as a child just as it is today. In order to test the veracity of the legend, this study performed subsurface imaging of the tree using holographic subsurface radar (Rascan), and 3-D measurements of the magnetic field about the tree using cesium vapor sensors. The Rascan system used is a continuous wave subsurface radar that operates at 5 discrete frequencies between 1.5 and 2.0 GHz. Reflections from subsurface objects are recorded as the phase difference pattern between an internal reference signal, and the reflected signal. Thus, it is a microwave analogy for optical holography. Rascan records reflections with two receiving antennae - parallel and perpendicular to the transmitter - so a single set of scans provides ten images; five frequencies at two polarizations. This ensures that an object at arbitrary depth will produce a strong phase difference in one of the images. As a consequence, elongate objects that are angled from the plane of scanning (e.g. a dipping sheet) produce "zebra stripes" of contrast values that vary cyclically with depth. The presence of stripes, and their relative positions in the different frequency images (the movement of which has been dubbed the "zebra shift") is useful for determining the relative depth of different portions of a dipping planar, or curved subsurface object. Rascan images of the tree revealed a reflector that produces a zebra shift pattern reminiscent of a curved reflector. However, given the curvature of the tree trunk, the zebra shift is more likely to represent a flat reflector beneath a curved scanning surface - consistent with the presence of the sign. As an independent confirmatory method, the tree was also subjected to a magnetic survey. First, the tree was swept with a magnetic locator - which indicated a magnetic target within the tree. In order to determine the configuration of this target, magnetic total field measurements were collected at the nodes of a 3-D grid surrounding the tree. The geometry of this survey is quite different from traditional archaeological prospection magnetometer surveys and, despite the relatively high latitude of Donegal PA, the vertical orientation of the suspected target mimics the common difficulties with magnetic surveys at low magnetic latitude. Therefore, the analytic signal was calculated to provide an easily interpreted magnetic anomaly that, together with the Rascan images, suggests that the story of the swallowed Donegal road sign may be true.


GP22A-06
3-D Modelling of Magnetic Data from an Archaeological Site in Northwestern Tlaxcala State, Mexico
Chavez, R E (exprene@geofisica.unam.mx), Instituto de Geofisica UNAM, CD Universitaria Circuito Exterior, Mexico, DF 04510, Mexico, et al.

In Archaeology, geophysical methods had been applied usually in a qualitative form, limited only to the use of filters that enhance the data display. The main objective in this work is the implementation of a modeling technique that allows us to reconstruct the geometry of buried bodies and the determination of their depths. This is done by means of the estimation of the magnetic moments of archaeological objects using a three- dimensional mesh of individual magnetic dipoles using the least squares method and the singular value decomposition of a weighted matrix to solve the linear problem. The distribution and shape of the underlying archaeological remains can be inferred. This methodology was applied to an archaeological site called Los Teteles de Ocotitla, in the state of Tlaxcala, Mexico. A high-resolution magnetic prospection was carried out in three selected areas (terraces). The most important total field anomalies found on each area were inverted, obtaining results that were corroborated by archaeological excavations. This investigation demonstrates the potential of quantitative geophysical methods for the characterization of archaeological structures, in extension and in depth.


GP22A-07
Archaeometric Prospection Using Electrical Survey Predictive Deconvolution (ESPD)
Glover, P W (paglover@ggl.ulaval.ca), Université Laval, Département de géologie et de génie géologique, Québec, QC G1V 0A6, Canada

Once upon a time archaeological prospection was carried out mainly using electrical techniques. These days magnetic techniques and GPR are used by preference. However, we have shown that electrical surveying combined with the technique of predictive deconvolution is very effective at finding buried features where the shape of the feature can be predicted in advance. One such type of feature is the Grubenhaus (or sunken-featured, sunken-floored building, or SFB). Grubenhaüser exist in the archaeological record as individual well-defined oblong pits that have been filled and buried with other material. Aerial photographs at New Bewick in Northumberland, northern England (UK Grid reference NU061206) showed quasi-rectangular features similar to those on aerial photographs at the nearby Anglo-Saxon palace of Milfield (NT941339) which had been confirmed by excavation to be Grubenhaüser. Several electrical resistivity surveys were carried out over the area with an ABEM Mk II Terrameter and a multiplexing box serving 31 electrodes in line at any given time. Both double-dipole and Wenner configurations were used with an electrode spacing of 1 m. Data was acquired in blocks of 30 m by 30 m during a period of dry summer weather while the field was under young winter wheat. The Wenner array produces a characteristic 'M' or 'W' shaped response over filled in excavations such as those expected to represent a Grubenhaus. While this seems a disadvantage in the first instance, it can be used to improve the data. Such anomalies were present in the raw New Bewick data. The resulting data were analysed using 1D and 2D predictive deconvolution in order to remove the Wenner response. The deconvolution was carried out using an inverse matrix element method. The filtered results indicated the presence of an anomaly that is consistent with a Grubenhaus measuring about 5 m by 4 m and with a pit depth of 0.6 m below 0.5 m of topsoil. The results also showed broader areas of increased resistivity which have been attributed to compaction resulting from human and animal movement. Following the geophysical study the site was excavated (T. Gates and C. O'Brien "Cropmarks at Milfield and New Bewick and the Recognition of Grubenhaüser in Northumberland." Archaeologia Aeliana 5th series, Vol XVI, 1988, 1-9) and a Grubenhaus was discovered at the site. The excavated Grubenhaus measured 4.7 m by 3.9 m with a pit depth of 0.5 m below the base of the topsoil. The deconvolved Wenner data performed better than the double-dipole resistivity survey but was marginally slower.

Friday, May 29, 2009

Archaeomagnetism abstracts from AGU, Toronto

Here are the abstracts on archaeomagnetism from the session I co-organized at the just completed American Geophysical Union Joint Assembly:

Archaeomagnetic Study performed on Early Medieval Buildings from western France
Chauvin, A (Annick.Chauvin@univ-rennes1.fr), Géosciences-Rennes, Université Rennes 1, CNRS UMR 6118, Campus de Beaulieu, Rennes, France et al.

A multiple dating study, involving a collaboration between specialists of dating techniques (thermoluminescence (TL) and radiocarbon), historians of art and archaeologists, has been carried out on several early medieval buildings from western France. The early medieval period is not well known especially in France where there is a lack of visible evidence that identifies pre-Romanesque architecture. The majority of buildings to have survived from this period are religious ones, considered important enough to be made of strong, non-perishable material such as stone or brick, as for example the churches of Notre-Dame-sous- Terre in the Mont-Saint-Michel or St Martin in Angers. Due to their significance in architectural history, it is imperative to position them accurately in the chronology of the history of art. Bricks are often used to build up round-headed arches or to reinforce the frame of a wall with bonding courses in those churches. TL dating and archeomagnetic analysis were performed on cores drilled within bricks while radiocarbon dating were undertaken on coals found within mortars. In order to increase the number of data during the early Middle Ages, archeointensity determinations using the classical Thellier technique with anisotropy of thermal remanence and cooling rate corrections were performed. Archaeomagnetic directions were used to recognize the firing position of bricsk during manufacture. Reliable and precise ages were obtained on the church Notre-Dame-sous-Terre; they indicate two phases of building in 950±50AD and 990±50AD. Mean archeointensities obtained on 17 (21) samples from the first (second) phases appears very closed 69.1±1.2 and 68.3±1.6 microTesla. Ages and archeomagnetic results obtained on 4 other sites will be presented and compared to the available data in western Europe.
News story on Chauvin presentation


European Archaeomagnetism: Progress and Problems
Evans, M E (evans@phys.ualberta.ca), Institute for Geophysical Research, University of Alberta, Edmonton, AB T6G 2G7, Canada et al.

Much progress has been made since the seminal work of Giuseppe Folgheraiter (1856-1913) in the late 19th century. So much so that recent advances now make it possible to draw up complete isogonic and isoclinic maps for Europe and adjacent areas spanning the last three millennia (Pavon-Carrasco et al., 2009). Results based on multiple independent studies, with high precision and good age control are crucial and should be recognized as "anchor points" (e.g. Pompeii). On the other hand, the nagging problem of outliers persists. Among the possible causes are magnetic refraction, physical distortion, and inadequate chronological control. Some examples, drawn from our own investigations over the last 30 years, will be discussed in detail. These include previously unpublished data from a detailed study (more than 100 samples) of a kiln in southern Italy, and an apparently good (but aberrant) archaeodirection from a kiln in southern Spain.


Regional Archeomagnetic Model for Europe for the Last 3000 Years: Application to Dating

Pavón-Carrasco, F (fjpavon@fis.ucm.es), Grupo de Paleomagnetismo. Dpto. de Geofísica y Meteorología, Universidad Complutense de Madrid., Avda. Complutense, s/n., Madrid, 28040, Spain et al.

Recently a new regional archeomagnetic model in Europe for the last three millennia has been proposed. This model, SCHA.DIF.3K (Pavón-Carrasco et al., 2009, Geochem. Geophys. Geosyst., doi:10.1029/2008GC002244, in press), is based on a Spherical Cap Harmonic Analysis (SCHA) for spatial representation and sliding windows method in time. The model provides information of both directional and intensity variation of the Earth's Magnetic Field for the last 3000 years in the European region. One of the immediate applications of SCHA.DIF.3K regional model is its use as tool for archeomagnetic dating. So far the PalaeoSecular Variation Curve (PSVC) determined for a region has been used for archeomagnetic dating. The limitation of this application is the distance from the dating point to the location of the reference curve (the relocation error). In addition it must be borne in mind that the PSVC are individually generated for each region, so there is no consistency enforced between curves from neighboring areas. The use of the SCHA.DIF.3K model as a tool for archeomagnetic dating represents an improvement for several reasons. First of all, the regional model has been generated considering all elements of the geomagnetic field (declination, inclination and intensity). Second, the regional model is built with an in situ archeomagnetic database. Furthermore, the database covers the whole time period from 1000 BC to 1900 AD, while the database used in the PSVC has gaps of data for any time interval. Finally, and more important, we can generate a PSVC at the location of the archeological structure, avoiding in this way the relocation error associated with traditional PSVC. To demonstrate the utility of the regional SCHA.DIF.3K model, we have used it to date several archeological structures and we have compared results with the archaeological information and/or archeomagnetic dating provide by the use of the PSVC.


The Mesoamerica Secular Variation Curve. A continuous research since 1999
Soler-Arechalde, A M (anesoler@geofisica.unam.mx), Universidad Nacional AUtonoma de Mexico, Instituto de Geofisica, Ciudad Universitaria, Del. Coyoacan, Mexico, DF 04510, Mexico et al.

Since 1999 we have been working on improving the Mesoamerica Secular Variation Curve. We re-sampled some sites that Wolfman initially used in its first proposal of this Curve, such as Teotihuacan, Teopancazco and Tula. Wolfman 's curve only had 4 radiocarbon dates directly associated with the sampled sites; the other dating were actually stratigraphic and ceramic correlations. More than 28 radiocarbon dates have been incorporated from AD 60 to 560 from samples associated to Teotihuacan civilization, 13 more from Xochicalco and 10 from Tula. More than 1000 specimens, from 12 twelve sites were fully processed with alternated field demagnetization We have been working during the excavation campaigns and training the archeologist to get their samples. A 100-year moving window was employed to get the average poles. A Bayesian statistic has been employed in order to improve our curve. We still denote a lack of data from two time intervals: from 0 to 200 and from 1000 to 1600. We are now working on it, collecting samples from these periods, such as those from La Joya, Ver, which are now been processing and from which some preliminary results will be reported.


Dating Post-Medieval Archaeology: Which Global Geomagnetic Field Model to use?
Lodge, A (a.lodge@liv.ac.uk), University of Liverpool, Department of Earth and Ocean Sciences, Jane Herdman Laboratories, 4 Brownlow Street, Liverpool, L69 3GP, United Kingdom et al.

The scientific dating of Post-Medieval archaeology (16th Century onwards) is problematic as most methods cannot provide any better resolution than may be apparent from contextual or stylistic considerations. As high resolution global geomagnetic field models exist for this period, archaeomagnetism offers the possibility of bi-decadal dating of burnt in situ structures, with implications for the management of cultural heritage. The question arises as to which global geomagnetic field model is most appropriate for this dating? Should the high resolution historical field model, gufm (Jackson et al., 2000, Four centuries of geomagnetic secular variation from historical records, Phil. Trans. Roy. Soc. Lond. A, 358, 957- 90.) which covers the period 1590-1990 AD and is based on data from ship's logs be used, or should an archaeomagnetic model such as GMADE2K.2 (Lodge & Holme, 2008, Developing a global geomagnetic field model for archaeomagnetic dating in Europe for the last 2000 years (updating GMADE2K.1 to GMADE2K.2), Geophys. Res. Abstr., 10, Abstract EGU2008-A-03470) be used? In general a higher accuracy can be expected from the historical model, but the modeling strategy for gufm is aimed at investigating the magnetic field evolution at the core-mantle boundary, whilst GMADE2K.2 is developed to serve as an archaeomagnetic dating tool. If we compare secular variation curves in Europe for declination at this time, then the two models agree very well. For inclination however, there is a discrepancy pre-1800 AD between the two models, with the historical model tending to higher inclinations. Here we study the possible causes of this discrepancy: How reliable are the early historical inclination data? How reliable is the historical model at this time - is the inclination being affected by the domination of declination data? Finally, are the archaeomagnetic data systematically low, possibly caused by undetected magnetic refraction? The advantage of constructing global geomagnetic field models is that the inter-dependence of the components is taken into account. However, if we cannot reconcile the archaeomagnetic models and data with the historical model and data, then dating remains problematic.