Wednesday, October 28, 2009

Bleeding for my craft

Hi All,

A brief update from the lab. Today I taught the students how to make stone tools, often called "flint knapping." Several of the students were really looking forward to this activity. They were pretty excited to try working the obsidian nodules into biface tools.
I'm afraid there weren't any budding Homo erectus the group, but they could have passed for Homo habilus.

All in all, however, they did better than Jessica and me. The total injury count (requiring band-aids):
Professor: 2
TA: 2
Class: 1 (and there are five of them!)
Next week, we are going to talk about glassmaking and archaeological analysis of glass, but we will also pull out the lithic fragments from the Davenport site and apply some of the practical skills everyone learned, using the new vocabulary to say, "This is the proximal and medial segment of a secondary reduction flake, complete with hackle lines and an eraillure scar indicating the striking platform above the bulb of percussion."

Mobile blog post

Thursday, October 22, 2009

154 Years Ago This Week

A little while ago, Noel Carmack emailed me about our research on the Davenport Pottery. Mr. Carmack teaches painting and drawing at the College of Eastern Utah. He wrote to me because he and Charles M. Hatch are just finishing a manuscript for publication with USU Press. They have edited the journals of James Henry Martineau, an early resident of Parowan and a surveyor.

Mr. Carmack wrote to me that he'd discovered something in Martineau's diary and he wanted to exchange information. In particular, he said to me that on October 29, 1855, Martineau had written:

"Oct. 29/To day, Thomas Davenport opened his kiln of Pottery. This is the first ever made south of Provo. I got two jars, some bowls and two meat dishes."

I was very excited by this reference because this diary entry had captured the exact day when the Davenports opened their first kiln of ware produced at their shop in Parowan. Readers that have been following the blog will remember Thomas's words transcribed from his now missing diary:

"I arrived in Parowan on November 4, [1852]. . . . I farmed and worked at my pottery trade until November 1855. I burned my first kiln, but it was nearly all broken. . . . I had another son born, but he only lived until August and died of the flu. . . . I burned another kiln of pottery but it was mostly broken. In the fall of 1856 we [Thomas and Sarah Burrows Davenport] got our endowments at Salt Lake City and stayed there until the spring of 1857. I then burned another kiln and about one third of these pieces were good. In 1851 [sic; 1859?] I built a house with six rooms and we moved into it. I had now learned to burn my ware without breaking it" (Nielsen 1963: 103).

Martineau's diary shows us that this transcription of Thomas Davenport's diary is probably accurate and that the Davenports opened their first kiln on October 29th, 1855------ 154 years ago (next week)! We also know that it took almost exactly three years to the day for the Davenport family to set up their household, farm, and shop until the first kiln firing.

My deep thanks to Noel for emailing me with this information.

Saturday, October 10, 2009

Rehydroxylation Dating-- testing a new tool!

While we were digging in the field this summer, a team of seven materials scientists (led by Moira Wilson) from the University of Manchester and the University of Edinburgh and Ian M. Betts, an archaeologist with the Museum of London, published a paper in the Proceedings of the Royal Society A called "Dating fired-clay ceramics using long-term power law rehydroxylation kenetics."

Three Michigan Technological University students, Helen Ranck, Patrick Bowen, and Jessica Beck, are trying to replicate the technique.

Materials scientists and engineers have known that ceramic minerals slowly reabsorb water from the environment after they are fired. Dr. Wilson's team discovered that the rate at which environmental water recombines with clay minerals as hydroxyls is governed by a kinetic law at the nano-scale. They found that the rate was influenced by temperature, but was not changed by the quantity of water present in the environment.

Scientists could actually measure the rate of water mass gain for any given ceramic fragment by heating a sample in a kiln and then waiting and measuring the increase in mass as the clay molecules slowly recombined with environmental moisture at a known temperature. Lab researchers can then calculate the date of firing with these known measurements:

1. This determined rate of water mass gain.
2. The mass of the sample after excavation (when it contained all the re-bonded water).
3. The mass of the sample after the test firing (mass of the ceramic fragment minus the molecularly recombined water mass that it had absorbed since it was fired).
4. The average temperature through time the sample experienced since firing in the depositional environment.

Of course, including the +/- error, universal in archeometric dating.

If this technique works as well as the authors assert, it will add another powerful tool to archaeological techniques around the world. It will also revolutionize the Utah Pottery Project. Remember that one of the main goals of our archaeological research is to reconstruct the learning process through which these individual potters or potting groups, such as the Davenport family, adapted their skills and knowledge to Utah's new environment and raw materials.

One of the biggest problems we've had is that we can not use the ceramic fragments themselves to date the features full of broken kiln wasters, such as Andy's excavation of the cellar feature this summer. We rely upon stratigraphic clues (that waster pile is older than X, but younger than Y) or other artifacts found in the deposits, like stylish imported ceramic fragments, which can be dated. The features full of industrial wasters only rarely also contain other clues, however.

There are some other archaeometric techniques archaeologists use to date ceramics directly, such as Archaeomagnetic Dating and Optically Stimulated Luminescence. These techniques are useful also, but are either very specific to only work on kiln foundations (archaeomagnetic) or expensive and require expertise we don't have (OSL or TL). Either way, most of those techniques work better when applied to the distant past, and not the nineteenth century.

Historical Archaeology is like ethnoarchaeology in many ways. Given that we are studying people and sites in the historic period, we know a great deal more about accurate temperatures than archaeologists studying deep antiquity. I have the advantage of knowing the year, and even the month, during which some of these ceramics were fired. I hope we can test and refine the technique to higher levels of precision.

If this technique works as described, we will have an inexpensive tool that will allow us to build direct chronologies from the waster fragments. We will be able to sort the Davenports' waste into categories and know which ones reflect the steep learning curve from the 1850s and which pieces have clues about ongoing improvement and the training of the next generation of potters!

Moira Wilson corresponded with me over the summer while we were digging, and I appreciate her encouragement to consider application of her team's work. I am excited to be working with this puzzle with Jaroslaw W. Drelich, an associate professor in MTU's Department of Materials Science and Engineering. The original article appeared here. Useful discussions and interesting commentary about rehydroxylation dating appeared here, here, and particularly here.

Saturday, October 3, 2009

First Fall Term Update!

The Utah Pottery Project is back on-line at this blog and on Facebook!

After a long break from the research blog, I am again posting updates. Starting today, I will write about our laboratory research. As we wash, catalog, and label the artifacts from last summer's dig at the Davenport Pottery Site, I'll post progress reports and connect the fieldwork with our lab analyses. Several interesting analyses are developing, and I will post updates when I can.

If I'm lucky, perhaps some of the students will write about what they are trying to learn in their projects.

There are several people helping out with the lab work and analyses right now. Jessica Montcalm, the project field director, is leading the processing of the artifacts in the lab, managing the flow of cleaning, conserving, and cataloging. Frank McGuire has also continued on since his time in the field. He has been helping Jessica to process the finds. This week, Frank and Jessica finished floating the soil samples taken during the dig this summer. The students enrolled in my Archaeological Sciences class helped with this process as they learned about floatation, archaeobotany, and geoarchaeology during the first few weeks of the term.

In this picture, Frank is measuring sample volume and mass before floatation.
After putting samples of dirt from different features and soil layers into water, light organic matter floats to the surface where we catch it for analysis. This method allows us to find seeds, charcoal fragments, bits of wood and shell-- lots of detail about the environment surrounding the site!

Jessica and Frank have help from some of the students enrolled my Archaeological Sciences course at Michigan Tech. Some of the class members have elected to study the Davenport Pottery dig artifacts for their semester research projects.

Allison and Jeff have decided to study the artifacts from the cellar feature that Andy excavated over the summer. They are going to help clean and label all the fragments from this feature so that they can try reconstructing all the broken pots. They will take out all the sherds, like the large ones pictured in the bucket below, and spread them out on the lab tables like a giant archaeological jigsaw puzzle!