Greenbrier (Great Smoky Mountains) - Geology

Geology

The ridges surrounding Greenbrier are among the highest in the Appalachian range. To the east is the Guyot massif, which rises to over 6,000 feet (1,829 m) for long stretches. To the west is the Le Conte massif, which culminates in a 6,593-foot (2,009 m) summit. The ridge immediately to the south connecting the two massifs, known as "the Sawteeth," consists of a series of jagged, steep cliffs, the most well-known of which spans the northern face of Charlies Bunion. Greenbrier Pinnacle, a 7-mile (11 km) ridge descending from the western flank of Old Black westward to the Middle Fork valley, nearly closes off Greenbrier Cove entirely. Over a dozen streams flow north from the crest of the Pinnacle, each of them cutting narrow hollows with traces of fertile bottomland.

Greenbrier is underlain by a Precambrian metamorphic rock formation of the Ocoee Supergroup known as Roaring Fork Sandstone. This rock type, created from ancient ocean sediments 750 million years ago, dominates the mid-level elevations in the north-central Smokies. As the elevation increases to the south, a thrust fault known as the Greenbrier Fault separates the Roaring Fork sandstone from Thunderhead sandstone and Anakeesta Formation, both of which are common along the Smokies crest. To the north, as the land flattens out (near the park boundary), another thrust fault, the Gatlinburg Fault, separates the Roaring Fork formation from a layer of siltstone, which underlies the foothills around Emert's Cove.

Like the Sugarlands and Roaring Fork to the west, Greenbrier's bottomlands and streambeds are coated with sandstone, phyllite, and slate rocks of all sizes. During the Ice Ages, the cold weather caused fracturing of the high mountain slopes, creating boulder fields. Over the centuries, erosional forces carried these boulders to lower elevations. Greenbrier's residents used these rocks for fencing in lieu of barbed wire, creating the long rock walls that criss-cross the area today.