Abstract The Winding Stair Gap exposure is a l,220-ft-(370 m) long road cut on U.S. 64 in Macon County, North Carolina. The outcrop is located in the northeastern part of the Rainbow Springs 7½-minute Quadrangle within the Nantahala National Forest, 10.5 mi (17.5 km) south of the U.S. 64 South and U.S. 441 intersection near Franklin, North Carolina (Fig. 1). Paved parking areas suitable for buses are available at the crest of Winding Stair Gap adjacent to the Appalachian Trail, and just north of the exposure at a scenic overlook. Access to the upper tiers (for specimen collecting) is via the northern end of the outcrop.

ABSTRACT The Appalachian Mountains expose one of the most-studied orogenic belts in the world. However, metamorphic pressure-temperature-time ( P-T-t ) paths for reconstructing the tectonic history are largely lacking for the southernmost end of the orogen. In this contribution, we describe select field locations in a rough transect across the orogen from Ducktown, Tennessee, to Goldville, Alabama. Metamorphic rocks from nine locations are described and analyzed in order to construct quantitative P-T-t paths, utilizing isochemical phase diagram sections and garnet Sm-Nd ages. P-T-t paths and garnet Sm-Nd ages for migmatitic garnet sillimanite schist document high-grade 460–411 Ma metamorphism extending south from Winding Stair Gap to Standing Indian in the Blue Ridge of North Carolina. In the Alabama Blue Ridge, Wedowee Group rocks were metamorphosed at biotite to staurolite zone, with only local areas of higher-temperature metamorphism. The Wedowee Group is flanked by higher-grade rocks of the Ashland Supergroup and Emuckfaw Group to the northwest and southeast, respectively. Garnet ages between ca. 357 and 319 Ma indicate that garnet growth was Neoacadian to early Alleghanian in the Blue Ridge of Alabama. The P-T-t paths for these rocks are compatible with crustal thickening during garnet growth.