INTEGRATING ARCHAEOBOTANY AND GEOARCHAEOLOGY USING FLOTATION RESIDUES: BENEFITS, CONSTRAINTS, AND A CONSIDERATION OF CALCIUM OXALATES

Flotation residues (<1mm dust fraction) provide a useful and underutilized opportunity to integrate macro-botanical, micro-botanical, and other archaeological datasets to explore the past. This paper discusses the types of remains that are present within flotation residues, including phytoliths, starch grains, and dung spherulites, through a series of case studies from Epipalaeolithic–Neolithic Abu Hureyra and Ubaid/Late Chalcolithic Tell Zeidan, in Syria that focus on fuel, food, farming, and animal management. Within the macro-botanical literature from SW Asia, two schools of thought have emerged on how plants are predominantly deposited on archaeological sites. Some argue that plants are predominantly deposited via crop-processing providing information on human diet, whereas others elevate burned crop dung, which provides insight into animal diet and management. Observations of dung spherulites within flotation residues provide objective information on dung, documenting varied depositional processes between samples that reflect diverse uses of plants in the past, thereby placing interpretation of plant assemblages on a firmer footing. The microbotanical literature rarely engages with this debate, but the same principles and need to objectively detail depositional processes apply.

Flotation residues regularly contain phytoliths, starch grains, and ash pseudomorphs/calcium oxalate crystals, providing a way to explore taxa and plant parts that do not preserve well in macro form. A newly prepared reference collection focusing on calcium oxalate crystals from a range of important economic taxa that tend to be underrepresented in macro- and phytolith forms is presented.

While sediment remains the preferred base to extract microbotanical remains from, flotation residues provide a viable alternative for important sites that were excavated prior to the development of routine sediment sample collection. Data gathered from flotation residue should be considered carefully and additional studies comparing the recovery rates from sediment and flotation residues are needed. Flotation residues lack the spatial resolution associated with micromorphology samples, but can provide a helpful big-picture sequences that mirror the spatial scales of macro-botanical analyses, thereby providing an additional perspective of the past.