We were in the lab all day today. You might think that sounds like a long time to be “stuck” in a lab but it was really interesting and we did a wide variety of activities. First we learned about several techniques for dating sites. The first was dendrochronology — tree ring analysis — and while most of us were familiar with the concept we soon realized how much you could do with it. By using 3 samples that overlap in time, you can establish what year a tree died. Some trees, such as cottonwood, don’t develop tree rings. When you find charcoal in a hearth in a pit house or kiva, you can use that to identify what kinds of trees the community used for firewood. You can use trees to establish years of drought (I always wondered how they knew a drought occurred in, say, 1361) because the lines are thinner. Once you’ve established a few tree patterns from a region, it’s good for the whole region because they would have the same conditions.
Bore samples are really good because they don’t harm the tree and you can see a sample laid across the “tree cookie” and a board labelling it and counting the years. It’s important to have the outside edge because it’s the most recent. We can use the tree dates on a site to date the pottery found there. We got to try our hand at reading some samples and did pretty well with it.
We also learned about Archaeomagnetic dating — based on the magnetic pole actually not being perfectly north and we learned how a piece of charcoal or adobe, something that had been heated along time ago, retained its north orientation and the year it was used can be established by lining it up with the part of the “meandering” chart which has been established back to the 1600s.
Then we got to try our hands at cataloging, flotation sorting and analysis, washing artifacts and entering catalogue data into a computer. It was really a lot of fun and nice to have lunch on campus and sit and relax.