In archaeology, the general meaning of horizon is a distinctive type of sediment, artefact, style, or other cultural trait that is found across a large geographical area from a limited time period.
Most typically, there is a change in the type of pottery found and in the style of less frequent major artefacts.
Across a horizon, the same type of artefact or style is found very widely over a large area, and it can be assumed that these traces are approximately contemporary.
An archaeological horizon can be understood as a break in contexts formed in the Harris matrix, which denotes a change in epoch on a given site by delineation in time of finds found within contexts.
An example of a horizon is the dark earth horizon in England, which separates Roman artefacts from medieval artefacts and which may indicate the abandonment of urban areas in Roman Britain during the 2nd to 5th centuries.