The first fossiliferous Pridolian beds from the southern Appalachians in northern Alabama, and the age of the uppermost Red Mountain Formation

Abstract

Fossiliferous Late Silurian strata have not previously been recognized in the folded Appalachians south of central Virginia (Berry and Boucot, 1970). In this note, we report that the Red Mountain Formation at two localities in northern Alabama (Sparks Gap and Clear Branch Gap in Red Mountain near Birmingham, Figure 1) has yielded fossils like those of the Cobleskill Limestone (Pridolian, latest Late Silurian). The Red Mountain Formation in this area consists of interbedded sandstone, mudstone, claystone and limestone; some beds are hematitic and most are intensely weathered. The critical fossils are the brachiopod Eccentricosta sp. cf. E. jerseyensis (Weller, 1900) and the ostracode Welleriopsis? sp. aff. W.? pustulosa Berdan, 1972. The Eccentricosta beds at Sparks Gap and Clear Branch Gap are assigned to the Red Mountain because they are lithologically similar to lower beds in the formation. Thus the youngest part of the Red Mountain Formation in the Birmingham area is of Late Silurian, Pridolian, age. At Sparks Gap, underlying beds yielded Late Silurian corals that are not assigned to a faunal zone.