Because each stratum resulted from specific kinds of depositional processes at work over time, it is possible to chronologically relate the position of one layer to another. According to the law of superposition, since sedimentary layers accumulate upward through time, the oldest layers will always be the lowest vertical levels, while the most recent layers will be the highest vertical levels. This rule is not without its exceptions however, and secondary processes can make the process of understanding strata more convoluted. Strata represent a discrete period of time and so artifacts within the layer can be used to date the entire layer. When the artifact is an inscription or coin, a date of some precision can be assigned to the layer.
Pottery also provides a very effective means for dating in the Mediterranean.
Absolute dating techniques are generally not used in classical archaeology since they tend to provide less precise dates than the relative dating of artifact types. We refer to the processing and interpretation of the cultural remains collected through archaeological fieldwork as analysis. Artifacts, ecofacts, and features say little themselves, but researchers can make meaningful inferences about these when they are studied closely and in detail. Analysis therefore is the examination, description, classification and identification of that material, as well as a consideration of its broader meaning. Processing decisions begin with the research design and the goals tailored for each project.