Virgilian series

{{Primary sources|article|date=November 2008}}

{{More footnotes|date=November 2008}}

The Virgilian series is the youngest part of the Pennsylvanian epoch in the North American geologic classification series.{{cite journal|last1=Heckel|first1=P. H.|last2= Clayton|first2=G.|title=The Carboniferous System. Use of the new official names for the subsystems, series, and stages|journal= Geologica Acta|date=2005|doi=10.1344/105.000000354|url=https://www.raco.cat/index.php/GeologicaActa/article/view/82340}} During Virgilian times, the top of the Conemaugh and the entire Monongahela group were deposited.{{cite journal|last1= Eble|first1=Cortland F.|last2= Pierce|first2=Brenda S.|last3= Grady|first3=William C.|title=Palynology, petrography and geochemistry of the Sewickley coal bed (Monongahela Group, Late Pennsylvanian), Northern Appalachian Basin, USA|journal= International Journal of Coal Geology|date=2005|doi=10.1016/S0166-5162(03)00110-1|url=https://doi.org/10.1016/S0166-5162(03)00110-1}} As with other Carboniferous series, it comprises cyclothems, or distinct cycles of sedimentary rock formation.