The depth of the strata within the master sequence provides the investigator with the relative date of any particular profile. Seriation is an archaeological technique involving the description of stylistic changes in artifacts and of changes in the popularity of distinct styles in order to accurately describe the sequence of variation over time. The seriation of stratified deposits permits archaeologists to assess the relative age of particular styles. Technological changes can be used for relative dating of archaeological material. The three-age system devised by the Danish archaeologist Christian Thomsen in the 1830s made use of technological criteria.
Biological criteria can also serve as a means for relative dating.
Fossils are useful because certain assemblages of species are characteristic of specific geological eras. Pollen analysis, or palynology, involves the microscopic examination of fossil pollen grains in stratified peat and lake deposits. The principle of stratigraphic dating is used to establish the relative age of these floral and fossil assemblages. Through the investigation of many different stratigraphic contexts, a master sequence of fossil and floral assemblages may be devised for a region. Listing from Electric Library , a pay service.