Lycopod abundance in coal is used to estimate climatic "wetness" during the Pennsylvanian period in the central Appalachian basin. Plants were identified from their anatomy using etched, polished coal rather than using permineralized peat, compressions/impressions, or palynology. The data indicate that two drier intervals occurred: one in the Westphalian B (middle of the Kanawha Formation), the other in the early Stephanian (Conemaugh Formation). Both drier intervals have been previously recognized in the Illinois basin, but only the second has been previously recognized in the Appalachian basin
In 9 of 18 localities, lycopod abundance decreases upward within coal beds, whereas at the other nine localities, no statistically significant trends in lycopod abundance were observed. An upward decrease in lycopod abundance is suggestive of coal that formed in the central region of a domed peat swamp, but peat-dome formation is not demonstrated. Within coal beds, pteridosperms are most abundant in samples which are split or contain abundant mineral matter.