Welcome back for the second installment of background information for GCAP 2011! While the last post described previous excavations at Mound No. 2, here I’ll focus on more recent, non-invasive survey of the Middle Woodland village at Garden Creek.
If you happened to drive through the Plott Farm neighborhood last February, you may have seen this redheaded fellow (above) walking across lawns and fields, carrying what looks like a handful of PVC pipes. Allow me to introduce Dr. Tim Horsley, geophysical archaeologist. Tim specializes in a special kind of archaeological site finding approach called geophysical prospection. In general, geophysical prospection involves the use of special machines that can detect variability in physical characteristics below the ground surface. Archaeologists are particularly interested in detecting variation that represents cultural deposits, distinct from the natural background geology.
To survey the Garden Creek village, Tim used a magnetometer, which detects interruptions in the earth’s background magnetic field. These interruptions can be caused by natural features (e.g., an iron-rich geological formation) or by human activities that affected the magnetic properties of soils, such as localized heating (e.g., a hearth) or the accumulation of organic debris and certain artifacts (e.g., a midden). Without a considerable amount of comparative data, it is difficult to determine precisely what a magnetic anomaly is solely on the basis of magnetometer results. However, this approach does indicate exactly where certain archaeological deposits are, allowing subsequent excavations to be more targeted and efficient.
Magnetometer survey was a critical component of the research design for the current phase of investigations at Garden Creek. First, it would generate a detailed map of a large portion of the village without damaging the archaeological record; after a week of surveying, it appears that the Middle Woodland occupation area is substantially larger than initially believed. Second, the survey would guide the placement of our excavation units so that we could be minimally intrusive — a matter of utmost importance when you are digging in people’s front lawns! The setting of the site in a modern neighborhood also posed a potential challenge. Modern construction is an iron-heavy enterprise, and there was a possibility that we would be unable to detect subtler, ancient remains among the magnetic disturbances caused by roads, power lines, septic tanks, even isolated nails and coins.
As we learned in the course of survey, the neighborhood setting was, in fact, a blessing in disguise. While some areas were obscured by modern construction, major portions of the site appeared to be remarkably well preserved. We think this is because many of the yards had never been subjected to mechanized plowing, which is often a culprit in damaging archaeological sites. In these areas, Tim was able to identify several dozen magnetic anomalies that could be the remains of hearths, pits, posthole clusters, middens, and possibly earthworks.
In light of these data, we have identified several different areas for excavation this summer. By targeting these units, we hope to get a better picture of the organization of the residential occupation at Garden Creek and the sorts of activities that were carried out there. I am especially interested in learning if this occupation changed alongside the emergence of monumental architecture (Mound No. 2) and increased participation in interaction networks. This will require that we precisely date newly discovered deposits and compare them to previously excavated deposits below the mound, which pre-date its construction.
To answer these and other questions, the next step is excavation. With the ability to show local residents exactly where we want to dig and the exact anomaly we plan to target, we have obtained permission to explore the history of several portions of the ancient village. To that end, we began with test excavations in early March, the subject of the forthcoming and final installment of project background information. For now, in closing, I must sincerely thank all of the Plott Farm residents who allowed Tim and me to walk back and forth (and back and forth…and back and forth…) across their yards; we look forward to working with you more this summer!