An absolute dating technique that estimates the calendar age of formerly living organic material by measuring the residual concentration of the radioactive isotope carbon-14 and applying a decay model and calibration to convert measured activity or isotope ratio into calendar years before present.

Principle

Organisms incorporate atmospheric 14C while alive; after death, 14C decays with a known half-life (~5,730 years). Measuring remaining 14C relative to stable carbon allows calculation of elapsed time since death, adjusted by calibration curves to account for past atmospheric 14C variations and reservoir effects.

Demonstration

Measuring the 14C activity of charcoal from a hearth; obtaining an activity corresponding to an uncalibrated age of 3,200 BP, then applying calibration to yield a calibrated calendar range (e.g., 1650–1600 cal BCE) with assigned probability intervals.

Misapplication

Applying radiocarbon ages from a sample affected by modern carbon contamination (e.g., root intrusion or conservation adhesives) without accounting for contamination; or using uncalibrated radiocarbon ages as direct calendar years.

Consequence

When used appropriately with proper pretreatment and calibration, radiocarbon dating provides quantitative age estimates and probability ranges that constrain timing of biological, archaeological, and environmental events within its effective range (roughly up to 50–60 kyr).

Reversal

Treating radiocarbon ages as exact single-year dates without calibration or uncertainty; reversal ignores measurement error, calibration wiggles, and reservoir offsets, producing misleading chronological precision.

Boundary

Valid for organic carbon-bearing materials (charcoal, bone collagen, peat, shells with caveats) within the method's effective age limit and where sample contamination and reservoir effects can be evaluated; not applicable to inorganic minerals lacking carbon or to direct dating beyond detection limits without specialized techniques.

Semantic Tension

Competes with relative dating and other absolute methods (e.g., dendrochronology, luminescence): radiocarbon provides direct dates for organic samples but must be calibrated and can be affected by reservoir and contamination issues, whereas dendrochronology can give precise calendar years where trees are available.

Synthesis

Radiocarbon dating quantitatively estimates the time since death of organic matter by measuring decayed 14C, then using decay models and calibration to translate measured signal into calibrated calendar age ranges; it is powerful within its limits but requires careful pretreatment, context evaluation, and calibration.