Archaeologists date artefacts by combining methods that establish either relative age or an estimated absolute or calendar age. There is no single dating technique that works for every artefact. The appropriate method depends on the material, its archaeological context, its expected age, the preservation conditions and the research question. Relative dating establishes that an artefact is earlier or later than another object or deposit, while chronometric dating provides a numerical age estimate or range. Archaeologists often combine several independent methods because each has different strengths and limitations. Stratigraphy, typology, historical documentation, radiocarbon dating, dendrochronology, thermoluminescence, optically stimulated luminescence, potassium argon dating and other techniques can all contribute to chronological reconstruction in appropriate circumstances.
Stratigraphy is one of the fundamental relative dating methods. When archaeological deposits remain undisturbed, deeper layers generally formed before higher layers. Artefacts found securely within a layer can therefore be assigned a relative position in the sequence. Archaeologists also study the relationships between structures and features. A wall that cuts through an earlier deposit is normally later than the material it cuts, while a floor built over an earlier structure is later than that structure. Stratigraphic reasoning is powerful because it directly reflects the physical sequence of deposition, but it can be complicated by later disturbance, erosion, construction, burrowing animals, agriculture and human movement of materials.
Typological dating compares artefacts according to form, style, manufacturing technique and technological characteristics. Many object types change gradually over time, allowing archaeologists to compare an unknown specimen with examples whose dates are independently established. Pottery styles, coin designs, weapon forms, glass vessels and architectural features can sometimes be chronologically sensitive. Typology is most reliable when supported by large comparative collections and independent dates. It should not be treated as an assumption that stylistic similarity automatically proves contemporaneity, because styles can persist for long periods, be revived, travel between regions or coexist with older forms.
Historical dating can be used when artefacts are associated with documents, inscriptions, dated buildings, coin issues or securely dated events. A coin bearing the image and title of a known ruler may provide a chronological constraint, while an inscription can sometimes give an explicit date. However, the manufacture date of an artefact may differ from its deposition date. An object can remain in use for years or centuries, be inherited, repaired or reused. Consequently, archaeologists distinguish between the date an object was produced, the period during which it was used and the date when it entered the archaeological deposit. This distinction is particularly important when artefacts are found in later contexts.
Scientific dating methods provide numerical estimates but always involve assumptions and uncertainty. Radiocarbon dating measures the radioactive decay of carbon containing organic material, while dendrochronology matches tree ring patterns to established sequences. Thermoluminescence can date certain heated materials by measuring stored radiation energy released as light during laboratory analysis, while optically stimulated luminescence can estimate when mineral grains were last exposed to light. Other methods are applicable to particular geological or volcanic contexts. No scientific dating method should be selected simply because it produces a number. Researchers must determine whether the material and archaeological context satisfy the assumptions required by the method.
Sampling is a major part of archaeological dating. A laboratory may produce a technically precise result from a sample that is archaeologically inappropriate. For example, an old piece of wood incorporated into a later structure can produce the age of the wood rather than the date of construction. Contamination can introduce younger or older carbon into a radiocarbon sample. Mixed deposits can also contain materials from different periods. Archaeologists therefore select samples carefully, document their exact context and compare results with other evidence. Multiple dates from independent samples can reveal whether an apparent chronological pattern is robust or whether individual measurements are affected by contamination, reuse or unusual histories.
Calibration and statistical interpretation are important because some scientific dating methods do not translate directly into calendar years. Radiocarbon measurements are reported using radiocarbon years and must be calibrated against independently established records because atmospheric carbon levels have varied through time. Calibration can produce a probability distribution rather than a single calendar date. Archaeologists therefore report date ranges and probabilities rather than presenting uncertain measurements as exact years. Bayesian statistical methods can combine scientific dates with stratigraphic relationships and prior chronological information, producing more coherent estimates when the assumptions are justified.
The most reliable archaeological chronologies normally emerge from multiple lines of evidence rather than one isolated dating result. A pottery style may establish a broad period, stratigraphy may place it within a particular phase, a radiocarbon measurement may provide an independent numerical range, and historical records may narrow the interpretation further. Agreement between independent methods increases confidence, while disagreement requires investigation rather than automatic selection of the preferred result.
Dating artefacts is therefore a process of chronological reasoning involving material science, archaeological context, statistical analysis and comparative evidence. The goal is not merely to attach a number to an object but to establish a defensible relationship between the artefact, its production, use, deposition and wider historical sequence.
