Remarks on stratigraphical classification

Abstract

One may distinguish between chronostratic (or chronostratigraphical) classification (units with time boundaries) and protostratic classification (with quality boundaries). Protostratic classification embraces biostratic classification. Bio- and lithochronostratic units are chronostratic units originally based on biostratic and lithostratic data, respectively. It is suggested to retain the term zone (chronozone) for small chronostratic units based on palaeontological data and to use the term substage for small chronostratic units base on other data. Zonite is suggested instead of zone for small (proto-) biostratic units. The prefixes holo-, and mero- may be added to stratic terms when it is desirable to stress that they are based on total, local, or partial range, respectively. Mixed topostratic units are local units with one boundary based on palaeontological data and the other boundary on lithological data. Different types of time-correlation is discussed and it is distinguished between time-correlation of the same unit in different places (auto-correlation) and of different stratigraphical units (allo-correlation). Type sections are believed to be necessary for the boundaries of chronostratic units.