Virgilian series
The Virgilian series is the most recent part of the Pennsylvanian
The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...

Series (stratigraphy)
Series are subdivisions of rock layers made based on the age of the rock and corresponding to the dating system unit called an epoch, both being formally defined international conventions of the geological timescale. A series is therefore a sequence of rock depositions defining a...

 in the North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

n geologic classification series. In the older Appalachian classification system, this series was known as the Monongahela group. As with other Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...

 series, it comprises cyclothems, or distinct cycles of sedimentary rock
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....


Monongahela cyclothems (youngest at top)

  • Upper Little Pittsburgh
  • Lower Little Pittsburgh
  • Little Clarksburgh
  • Elk Lick
  • Duquesne
  • Gaysport
  • Ames
  • Harlem
  • Upper Bakerstown
  • Anderson
  • Wilgus
  • Upper Brush Creek
  • Lower Brush Creek
  • Mason
  • Mahoning
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