Published online by Cambridge University Press: 20 May 2016
The Bridgeboro Limestone, a rhodolith- and coral-bearing limestone in southwestern Georgia, has been assigned to the Vicksburgian Stage (Lower Oligocene) of the Gulf Coast based on the occurrence of the bivalves Chlamys (Anatipopecten) anatipes (Morton) and C. (Lyropecten) duncanensis Mansfield. This assignment is further substantiated by the recent recognition of the distinctive bryozoan Tubucellaria vicksburgica Canu and Bassler. The Bridgeboro also contains the larger foraminifera Lepidocyclina (Lepidocyclina) mantelli (Morton), L. (Nephrolepidina) yurnagunensis Cushman, and L. (Eulepidina) undosa Cushman, an assemblage indicative of the Lepidocylina (s.s.) subzone of the Eulepidina Zone of Early Oligocene age. These foraminifera are also characteristic of the Duncan Church beds of the Florida panhandle, and an assemblage of isolepidine and eulepidine Lepidocyclina also occurs in the Glendon Limestone of Alabama. On the basis of larger foraminifera, macroin vertebrates, and physical stratigraphic relationships, we propose that the Bridgeboro, Duncan Church, and Glendon are biostratigraphically and lithostratigraphically correlative. The Glendon Limestone has been previously assigned to nannoplankton zone NP22, and also occurs within the Cassigerinella chipolensis–Pseudohastigerina micra planktonic foraminiferal zone, both of Early Oligocene age. Based on correlation with the Glendon, the age of the Bridgeboro is thus Early Oligocene (Rupelian), middle Vicksburgian.