Archaeology is a discipline that is largely based upon accumulated knowledge. As more information is added, the interpretations and stories that follow generally become more fulsome, resonant, and better supported. A broadly parallel situation exists in large river bottomlands, where the environment is actively enriched by the accumulation of periodic flood deposits, adding essential nutrients and organics to the preexisting base or soil surface. We have discovered a similar type of feedback loop while processing archaeological flotation samples derived from ancient habitation sites located in numerous stream valley settings across the state. The West Illinois Field Station (WIFS) Macomb field station is currently home to the ISAS flotation laboratory, where flotation samples from projects across the state are processed. Leftover sediments have been repurposed in the on-site staff vegetable garden, once again enriching the local soils for a new food crop.
Soil samples derived from excavated Native sites are processed in the Macomb lab to recover charred plant and other food remains, as well as small-sized artifacts. These residues from earlier meals, as well as gardening and refuse disposal activities, inform archaeologists about the lifeways of these people–what they typically ate, the places they visited, and the natural resources they used to shape their homes, environment, and world. A bulk sample (typically ten liters) of the various sediments that fill most pre-contact pit features and house basins is collected in the field by ISAS archaeologists and transported back to the labs in large plastic bags with tags that provide the necessary details relating to their discovery context.
These soils are essentially washed in 55-gallon water-filled plastic barrels/drums using a screened wooden basket to contain the individual samples. The lighter artifacts (typically charred wood, nutshell, seeds, and other plant remains) generally float to the top and are skimmed off, whereas the heavier objects (bone, pottery, rock) sink and are collected separately.
The sediment washed away from these objects is suspended in the water and ultimately settles in the bottom of the barrel. Organically enriched mixtures of silt, loam, and sand accumulate in the flotation barrels over time, much like the fine sediments released by natural river/stream flooding events, and are periodically cleaned out to continue processing and avoid inter-site contamination.
A wooden box was built behind the Macomb lab to contain the muck removed from the barrels and this accumulation of discarded sediment is now several feet thick. Recently, we spent several weekends and evenings clearing the weeds, leveling the dirt, and hand tilling this area up, using the skills we had acquired with shovels during routine archaeological investigations. What was once unsightly has now been converted into a verdant, functioning vegetable garden planted, tended, and used by staff. Ironically, the accumulation of organically-enriched muck derived from processing archaeological flotation samples has created an incredibly productive environment for growing tomatoes, peppers, squash, pumpkins, and other plants originally domesticated by various Indigenous Peoples in the Americas. Thus, our study and appreciation of these earlier societies continue to feed not only our understanding of past human adaptations and accomplishments but also contribute to the actual nourishment of some ISAS staffers involved in this particular field of inquiry.