Wednesday, August 7, 2013

Flotation Machine in Action

Featured in a previous post, Sustainable Archaeology's soil flotation machine from R. J. Dausman Technical Services, Inc. was put through its paces today. A team from New Directions Archaeology Ltd. was on site to un-crate and set up the machine, running the first tests out in the Lawson village at the Museum of Ontario Archaeology, next door. They will be floating dry sediment samples over the next few days that they have collected from some recent excavations the company has been working on.

The machine requires access to running water for its initial fill, as well as access to a source of electricity for circulating the water in the tank. After its initial fill, the machine recycles water within itself to allow for light-fraction flotation, and heavy-fraction rinsing with an attached spray-hose. The material captured in the screens is then allowed to dry on newspaper before it is packaged, and later analyzed. The fine mesh, as seen in the images below, allows for the capture of tiny floating artifacts, such as tobacco seeds. A courser mesh filters the heavier fraction of sediment, which can include artifacts such as shell, bone and pieces of flaked stone tool.