The Fort Payne Formation, or Fort Payne Chert, is a geologic formation found in the southeastern region of the United States. It is a Mississippian Period cherty limestone, that overlies the Chattanooga Shale (or locally the ), and underlies the St. Louis Limestone (lower in Alabama). To the north, it grades into the siltstone Borden Formation. It preserves fossils dating back to the Carboniferous period. Eugene Allen Smith named the Fort Payne Formation for outcrops at Fort Payne, Alabama.