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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 ...
The basic concept in stratigraphy, called the law of superposition, states: in an undeformed stratigraphic sequence, the oldest strata occur at the base of the sequence. Chemostratigraphy studies the changes in the relative proportions of trace elements and isotopes within and between lithologic units.
Type locality, also called type area, is the locality where a particular rock type, stratigraphic unit or mineral species is first identified. [1] If the stratigraphic unit in a locality is layered, it is called a stratotype, whereas the standard of reference for unlayered rocks is the type locality. [2] The concept is similar to type site in ...
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
Customarily, only distinctive beds, i.e. key beds, marker beds, that are particularly useful for stratigraphic purposes are given proper names and considered formal lithostratigraphic units. [18] [19] In case of volcanic rocks, the lithostratigraphic unit equivalent to a bed is a flow. A flow is “...a discrete, extrusive, volcanic rock body ...
Units in geochronology and stratigraphy [5] Segments of rock in chronostratigraphy Time spans in geochronology Notes to geochronological units Eonothem: Eon: 4 total, half a billion years or more Erathem: Era: 10 defined, several hundred million years System: Period: 22 defined, tens to ~one hundred million years Series: Epoch
This is a list of Global Boundary Stratotype Sections and Points.Since 1977, Global Boundary Stratotype Sections and Points (abbreviated GSSPs) are internationally agreed upon reference points on stratigraphic sections of rock which define the lower boundaries of stages on the geologic time scale.
Stratigraphic units in this group include (from oldest to youngest): Enon Formation: Contains subordinate sandstones and different types of thickly-bedded conglomerates, which consist mainly of quartzite and sometimes slate, shale, and charcoal. The clasts are poorly-sorted, sub-rounded to rounded pebbles and cobbles.