Chronological sequences based on successive horizontal displacements, such as sequential beach terraces. Stratigraphy is by definition obtained from superposed deposits, but other circumstances can be treated in the same way. For example, the oldest burials are likely to be those nearest the settlement, the top of a hill, or some other favored position. The later ones will be progressively further out as the cemetery expands. The concept can be a helpful tool in the interpretation of a site.