Geologic Period

A Geologic Period is a geologic time that represents a major subdivision of earth history (used to categorize and study geologic events and rock formations).

• AKA: Period (Geology), Geological Period.
• Context:
  • It can (typically) function as a Time Classification through geologic time scale.
  • It can (typically) serve as a Stratigraphic Unit through rock layer analysis.
  • It can (typically) provide Chronological Reference for geologic events and fossil records.
  • It can (typically) facilitate Cross-Regional Correlation through rock formation matching.
  • It can often contain multiple geologic epochs as time subdivisions.
  • It can often preserve distinct fossil assemblages from specific time intervals.
  • It can often reflect major environmental conditions of its time span.
  • It can often show evidence of significant evolutionary developments.
  • ...
  • It can range from being a Short Duration Period to being a Long Duration Period, depending on its time span.
  • It can range from being a Simple Stratigraphy Period to being a Complex Stratigraphy Period, depending on its rock record complexity.
  • ...
  • It can support geologic dating through stratigraphic correlation.
  • It can enable paleontological research through fossil preservation.
  • It can guide resource exploration through rock formation understanding.
  • ...
• Examples:
  • Phanerozoic Geologic Periods, such as:
    • Cenozoic Era Periods:
      • Quaternary Period with recent life forms.
      • Neogene Period with modern mammal diversification.
      • Paleogene Period with early mammal radiation.
    • Mesozoic Era Periods:
      • Cretaceous Period with dinosaur dominance.
      • Jurassic Period (201MYA - 145MYA) with flying reptiles.
      • Triassic Period (252MYA - 200MYA) with early dinosaurs.
    • Paleozoic Era Periods:
      • Permian Period (299MYA to 252MYA) with amniote diversification.
      • Carboniferous Period (359MYA - 299MYA) with vast coal formations.
      • Devonian Period with early tetrapods.
      • Silurian Period (444MYA - 419MYA) with first land plants.
      • Ordovician Period with marine invertebrate radiation.
      • Cambrian Period (541MYA to 485.4MYA) with trilobite dominance.
  • Precambrian Periods, such as:
    • Proterozoic Era Periods:
      • Siderian Period with earliest eukaryotes.
  • ...
• Counter-Examples:
  • Geological Era, which spans multiple geologic periods.
  • Geological Epoch, which is a subdivision of a geologic period.
  • Geological Age, which is a smaller time unit than a geologic period.
• See: Geologic Time, Geologic Time Scale, Stratigraphy, Paleontology, Mass Extinction Event.

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References

2014

• (Wikipedia, 2014) ⇒ http://en.wikipedia.org/wiki/Period_(geology) Retrieved:2014-9-20.
  • A geologic period is one of several subdivisions of geologic time enabling cross-referencing of rocks and geologic events from place to place.

    These periods form elements of a hierarchy of divisions into which geologists have split the earth's history.

     Eons and eras are larger subdivisions than periods while periods themselves may be divided into epochs and ages.

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