A recovery technique that separates light organic macro- and micro-remains (charred seeds, charcoal, small bones, other light botanical/organic fragments) from bulk sediment samples by agitating material in water (or other fluid) so buoyant components float for collection while heavier fractions sink for separate processing.

Principle

Differential buoyancy sorts organic and mineral particles: less-dense organic and charred materials remain suspended or float on the water surface and can be skimmed or collected onto meshes, producing a light fraction enriched in organics and a heavy fraction retained for lithic or faunal analysis.

Demonstration

Illustrative scenario: Soil samples from an occupation layer are bucket-flotated in the laboratory (Situation). The technician decants the floating material through a fine mesh and dries the recovered light fraction (Recognition/Action). Analysis yields charred seed assemblages used to infer crop use and to provide samples for radiocarbon dating (Consequence).

Misapplication

Assuming flotation recovers all organic evidence or that quantitative absence of organics in flot samples proves absence at the site. The error is ignoring recovery biases (mesh size, sample volume, taphonomy) and treating processed fractions as complete reflections rather than partial samples of the original deposit.

Consequence

Flotation increases recovery of small, light organics critical for palaeobotanical, dietary, fuel-use and dating studies; but results are structured by sampling strategy, mesh size and preservation, so assemblages must be interpreted as recoveries subject to methodological and taphonomic bias.

Reversal

In waterlogged, saline, or chemically altered sediments, flotation behavior may change (e.g., delicate organics destroyed or density altered) and alternative wet-sieving, chemical treatments, or flotation modifications may be required; dense organics or encrusted remains may not float.

Boundary

Clearly within: Laboratory flotation of bulk sediment to recover charred seeds and small organics. Boundary case: Wet-sieving a sample to recover small bones and sherds—useful but not equivalent to flotation for microbotanicals. Clearly outside: Dry sieving only, which recovers larger artefacts but misses many microbotanical remains.

Semantic Tension

Maximizing recovery completeness (fine meshes, large samples) ↔ Time, cost and preservation constraints (processing effort, sample representativeness). Intensive flotation improves botanical recovery but increases laboratory time and may introduce selection biases if not standardized.

Synthesis

Flotation is a method that deliberately concentrates light organic remains from sediments, transforming otherwise invisible botanical and some faunal evidence into analyzable assemblages; its scientific value depends on consistent sampling, mesh selection and transparent reporting of recovery biases.