Plant megafossils are relatively common below and above the Carboniferous-Permian boundary in terrestrial beds and have been used to recognize the systemic boundary in this facies. However the systemic boundary in the terrestrial realm seems to be different from that used in marine sequences. To resolve this difference, any purely terrestrial section must be correlated with one which has interfingering marine and terrestrial beds. Plant megafossils were collected from the Upper Pennsylvanian and overlying Permian(?) sequences in West Virginia, where the age assignment of the Dunkard Group has long been controversial. Similar collections in the uppermost Pennsylvanian and lowermost Permian of Kansas were used for a correlation of the two sections. The lithofacies in the tw areas are generally similar and both contain indicators of both wet and dry conditions. The plants occurring in rocks formed under relatively dry conditions change more rapidly and are therefore more meaningful for stratigraphic comparisons. The changes in the flora can best be expressed by the sequence of first occurrences (and to a limited extent, extinctions). The appearance of Callipteris, and specifically C. conferta, is clearly the best recognizable event in this stratigraphic interval. Based on these findings, the Washington coal bed in the Washington Formation, lower part of the Dunkard, would correlate approximately with the Topeka Limestone (middle Virgilian) of Kansas.

End_of_Article - Last_Page 970------------