NOTES ON FOSSIL COLLECTIONS FROM THE MAUCH CHUNK GROUP (UPPER MISSISSIPPIAN, CHESTERIAN) IN THE EARLY GEOLOGICAL SURVEY OF MERCER, MONROE, AND SUMMERS COUNTIES, WEST VIRGINIA

The paleontology of the Mauch Chunk Group (Upper Mississippian, Chesterian) of southeastern West Virginia was first studied in detail by Reger and Girty in 1926. However, although several collections of fossils were gathered, the species were only briefly listed. Further descriptions were not published, and the collections were apparently lost. Efforts to reexamine these faunas have produced several collections of marine and nonmarine invertebrates as well as vertebrate and plant fossils.

The rocks of the upper Mississippian Mauch Chunk Group show a transition from shallow, open marine limestones of the Greenbrier Series, into the mixed terrestrial deposits with thin marine incursions of the Mauch Chunk Group, and then into the coal-bearing Pennsylvanian siliciclastic deposits. The fossils reflect the transitional facies.

Comparison of recently found fossils with the fossil lists of Reger and Girty reveal some interesting points. First, they did not distinguish marine from nonmarine invertebrates. When sequence stratigraphers are looking for the maximum flooding surface, marine fossils are a good indication of this boundary. However, if it turns out that the fossils are nonmarine instead, this might result in confusion.

Second, the collections of marine fossils found recently are often similar but not identical to those Reger and Girty have listed. Nomenclatural differences play a small part. Different collecting locations of the same member as well as the local nature of the Hinton deposits probably play a larger part in the difference in collections.

However, in at least one instance, the differences in collections may be a result of mislabeling. Comparison of recent collections from the shales above the Stony Gap Sandstone with those of Reger from the Lower Bellepoint Shale suggests that one of his fossil lots may have been inadvertently augmented with fossils from another formation. Close reading of the report confirms this suspicion.

Since Reger’s report, descriptions of fossils from the study area include brachiopods, bivalves, a rostroconch, ostracodes, and a microconchid.