Flotation

By Judge Jones

Last Thursday and this Thursday, instead of going out into the field to excavate, my unit team and I stayed back at the house.  We performed flotation screening on ten and five liter soil samples that we have been collecting from every level we have dug. Our unit is investigating a prehistoric midden and the intent of this testing is to collect small floral and faunal samples that might otherwise be missed or discarded in the field using our regular quarter inch screening. The flotation device is a brilliant and efficient design created by Patty Jo Watson, modified by Christine Hastorf, and built for our use by Stefan Brannan and a local welder. It consists of a fifty-five gallon barrel, two aluminum buckets with the bottoms sawed off with screens put in their place, a hose connected to the barrel by a nozzle to fill it with water, and a common garden sprayer placed strategically under the largest bucket in the barrel to agitate the sediment.

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L to R: Judge (the author), Nate, and Kimi processing soil samples by flotation.

We emptied our samples, about three liters of dirt at a time, into the larger of the two buckets; then using our hands along with the garden sprayer underneath, we separated the sediment from the light and heavy fraction remains. The light fraction, which was mostly floral remains, would separate from the sediment, float to the surface and follow the overflow from the barrel into the smaller aluminum bucket and come to a rest in a well affixed cheesecloth. The heavy fraction, which contained many small and fragile bone fragments, would remain on the screen in the larger bucket in the barrel. As the sediment was removed and, settled to the bottom of the barrel all that is left was sand, grit, root mass, and bone. Removing the buckets carefully, so as not to lose the remains to the water and silt we had so carefully separated it from; we left the light fraction hanging in the cheesecloth and the heavy fraction out on a screen in the sun to dry. While we do not have time in the field,  once back in the lab the samples will be analyzed and hopefully the lives and means of the people who constructed and occupied Singer-Moye can be better understood.

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Kimi watches the light fraction being collected in cheesecloth placed over a bucket attached to the flotation barrel.

 

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About Dr. Jennifer Birch

I am an archaeologist who specializes in the Archaeology of Eastern North America. Conceptually, my interests are underpinned by the desire to understand how the lived experiences of individuals and communities articulates with long-term, large-scale processes of social and cultural change. My current research is concerned with the development of organizational complexity and diversity in eastern North America. Ongoing projects in Northeastern North America include: - Geophysical investigations of Late Precontact Iroquoian Villages - Regional synthesis of data on Iroquoian settlement patterns, including intra-site patterns, interregional interaction, and geopolitical realignment Ongoing projects in Southeastern North America include: - Multi-scalar investigations of the Late Woodland to Mississippian transition in the Deep South - Household and community archaeology at the Singer-Moye site
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