Theoretically, floating chronologies which cannot be tied to an absolute date (e.g.certain dendrochronological sequences) are relative chronologies even though the techniques are essentially chronometric.Another problem is that there may be gaps in the sequences of available timber, so that the chronology 'floats', or is not tied in to a calendrical date or living trees: it can only be used for .
The date on a coin is an absolute date, as are AD 1492 or 501 SYNONYMS OR RELATED TERMS: relative dates; relative dating techniques CATEGORY: technique; chronology DEFINITION: Dating methods where phases or objects can be put into a sequence relative to each other, but which are not tied to calendrically measured time.
It is the sequencing of events or materials relative to another but without linkage to ages in years bp (before present) or calendar years.
For example, stratigraphic units may be correlated using palaeontological criteria, methods, and position relative to the glacial-interglacial cycle by examining physical and biological attributes.
Correlation of fossil inclusions is a principle of stratigraphy: that strata may be correlated based on the sequence and uniqueness of their floral and faunal content.
Unless tied to historical records, dating by archaeological methods can only be relative -- such as stratigraphy, typology, , fluorine and nitrogen test, and radiometric assay.
Other methods include: coin dating, seriation, and amino-acid racemization.Dendrochronology, the relationship of dated ancient trees with live trees has no CATEGORY: technique DEFINITION: The use of various methods, often multiple methods, to demonstrate the equivalency of stratigraphic units.This term refers to the relation of one stratigraphical unit to another, by petrological, osteological, lithographic, cultural, chronological, or palaeontological means.SYNONYMS OR RELATED TERMS: chronometric dating; absolute dates; absolute chronology; absolute age determination (antonym: relative dating)CATEGORY: chronology; technique DEFINITION: The determination of age with reference to a specific time scale, such as a fixed calendrical system or in years before present (B.P., BP), based on measurable physical and chemical qualities or historical associations such as coins and written records.The central rings of this older tree may then be compared with the outer rings or a yet older tree, and so on until the dates reach back into prehistory.