Amanda Schmidt, an assistant professor of geology at Oberlin College, writes from Sichuan Province, China. She is studying the relative natural hazards of some places where people choose to live.
Monday, Aug. 8
The day’s work started with a brisk hike up to Old Zharu, a set of terraces and an abandoned village above the current Zharu Village. It took us about an hour to get from the new village to the terraces of the old village, where we collapsed in the shade to recover from the hike. Our plan for today was simple: to see if we could map offset in any terraces, get stuff to date and get more samples for grain size analysis. Since we were basically at the top of the terraces, we decided to work downhill over the course of the day and started in the abandoned village among the old houses.
At first we were quite confused by the stratigraphy we were seeing in the terraces. The first few terraces had almost no deposits in common — one would be all flow deposits and the next all loess. We were totally baffled by how we could have no flow on top of loess just below a terrace with all flow and no loess, but when I scrambled down to a little ledge to try to get an optically stimulated luminescence (O.S.L.) sample as high up as possible, we discovered some flow on top. Phew. Farther down in the terraces was a fabulous paleosol that we were able to use to measure offset between two terraces (about 12 meters, similar to what we found in Heye). Interestingly, in one of the lower terraces we found loess that looked like it had flowed a bit and was mixed with bands of crushed bedrock. Maybe the loess had moved as a block and the contact with the bedrock had mixed a bit. This was quite different from the other places where we find loess with rocks in it, as here the loess was still intact, just with little pockets of crushed bedrock.
Although we have previously found archaeological artifacts in Heye Valley (primarily bones and charcoal layers), Zharu surprised us. In part because no one has excavated here, we didn’t expect to find many artifacts or signs of prior occupation — some artifacts had previously been found only in lower terraces. But in one fabulous outcrop where we sampled for snails (they were huge!), charcoal and grain size, Xenna found half of a bead in a charcoal layer about two meters below the top surface and one meter above the ground. At another spot we found what looked like an old fire pit. It was about a meter thick, buried by a meter of flow and on top of at least a meter of loess.
The layers of charcoal looked almost laminated in the loess and were interbedded with loess. At a few spots there were red claylike layers that often are signs of past fire use. At another site, near where a donkey was hiding in the shade, Xenna found a paleosol with charcoal and huge numbers of bones. Possibly this was a site where people prepared animals. We also found a few suspected ceramics, but we don’t know enough to be certain that they aren’t thin pieces of sandstone. Since they are different from the rocks we normally see, we grabbed them to share with the archaeologists back in Chengdu.
Our work here is winding up — we leave for Chengdu on Saturday. With our large collection of samples, we were fortunate to find some expats from Chengdu who drove here and will help us carry everything back. But it will be a pain to carry the O.S.L. samples (they are in metal pipes and can’t be exposed to light) onto the airplane. Although it feels like we haven’t been here very long, Xenna and I are both quite tired and ready for a break; we have spent 15 full days and four half days in the field over the last 21 days. We’ve gotten a lot done, but I feel like we’re still scrambling to finish up the work we need to do. It’s a good thing my postdoc with the park is two years and I can come back next summer.
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References:
Schmidt, Amanda. 2011. "Faces and Artifacts at Old Zharu". New York Times. Posted: August 12, 2011. Available online: http://scientistatwork.blogs.nytimes.com/2011/08/12/faces-and-artifacts-at-old-zharu/
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