An
archaeological horizon is a widely disseminated level of common art and artifacts at an
archaeological site or, more usually, over a larger geographic area. It is a distinctive level in that site's or area's
archaeological sequence. An example of an archaeological horizon is the
Dark Earth horizon in England, which separates Roman artifacts from medieval artefacts and which may indicate the abandonment of urban areas in Roman Britain during the 2nd to 5th centuries. The term is especially used in the archaeology of
Pre-Columbian America. The term is used to denote a series of stratigraphic relationships that form an
archaeological phase, or are part of the process of determining the archaeological phases of a site. 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.