Pennsylvanian Subsystem

geology and stratigraphy

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July 20, 2026

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The Pennsylvanian Subperiod, a major interval of the Carboniferous Period, spanned from 323.2 to 298.9 million years ago. This geological time was characterized by significant fluctuations of shallow seas, with many non-marine regions near the Equator transforming into extensive coal swamps. These ancient swamps are the source of much of the coal mined today. The Pennsylvanian Subsystem is further divided into four stages: Bashkirian, Moscovian, Kasimovian, and Gzhelian. Prominent Pennsylvanian rock units in North America include formations in West Virginia, Oklahoma, Arkansas, and the Grand Canyon region, with major coal fields found across the United States.123

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geochronology
Completion of the Phanerozoic time scale
…from Pennsylvania, were formalized as Pennsylvanian in 1891 by the paleontologist and stratigrapher Henry Shaler Williams.
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…from Pennsylvania, were formalized as Pennsylvanian in 1891 by the paleontologist and stratigrapher Henry Shaler Williams.
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Carboniferous Period
Pennsylvanian subsystem
The type region for the Pennsylvanian Subsystem is located in central West Virginia. There the interval is represented by the following groups or formations (ascending order): Pocahontas, New River, Kanawha, Charleston Sandstone, Conemaugh, Monongahela, and basal Dunkard. Other well-known Pennsylvanian units in North…
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The type region for the Pennsylvanian Subsystem is located in central West Virginia. There the interval is represented by the following groups or formations (ascending order): Pocahontas, New River, Kanawha, Charleston Sandstone, Conemaugh, Monongahela, and basal Dunkard. Other well-known Pennsylvanian units in North…
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