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Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them. [1] The primary objective of biostratigraphy is correlation , demonstrating that a particular horizon in one geological section represents the same period of time as another ...
In biostratigraphy, biostratigraphic units or biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa, as opposed to a lithostratigraphic unit which is defined by the lithological properties of the surrounding rock. A biostratigraphic unit is defined by the zone fossils it contains. These ...
Variation in rock units, most obviously displayed as visible layering, is due to physical contrasts in rock type . This variation can occur vertically as layering (bedding), or laterally, and reflects changes in environments of deposition (known as facies change). These variations provide a lithostratigraphy or lithologic stratigraphy of the ...
A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features that characterize it. Units must be mappable and distinct from one another, but the contact need not be particularly distinct ...
[1]: 229 Thus, the fossils can be used to compare the ages of different rock units. The basic unit of biochronology is the biostratigraphic zone, or biozone, a collection of fossils found together in a rock unit. This is used as the basis of a biochron, "a unit of time in which an association of taxa is interpreted to have lived."
In biostratigraphy, a subdiscipline of geology, a taxon-range zone is the zone between the highest and the lowest stratigraphic occurrence of a taxon.Taxon-range zones are one of the fundamental biozones used in biostratigraphy and are named after the taxon whose range they describe.
Stages are primarily defined by a consistent set of fossils (biostratigraphy) or a consistent magnetic polarity (see paleomagnetism) in the rock. Usually one or more index fossils that are common, found worldwide, easily recognized, and limited to a single, or at most a few, stages are used to define the stage's bottom.
Lists of fossiliferous stratigraphic units in Europe; Lists of fossiliferous stratigraphic units in North America. Lists of fossiliferous stratigraphic units in Canada; Lists of fossiliferous stratigraphic units in the United States; Lists of fossiliferous stratigraphic units in Oceania; Lists of fossiliferous stratigraphic units in South America