The Brevard Fault Zone is a 700-km[1] long and several km-wide thrust fault that extends from the North Carolina-Virginia border, runs through the north metro Atlanta area, and ends near Montgomery, Alabama. It is an important Paleozoic era feature in the uplift of the Appalachian Mountains.[2]
Arthur Keith from the United States Geological Survey first identified an exposed segment of the Brevard Fault in 1905,[3] believing it to be a syncline. In 1932, Anna Jonas Stose’s used local petrology to identify the site as a thrust fault.[4] Stose, the first to trace the fault, is also credited with identifying that the rocks in the area must have been formed through deformation,[5] placing the Brevard Fault in a regional perspective.[3] Using modern methods of seismic reflection and high-resolution profiling, geologists have since discovered that the Brevard Fault Zone has undergone both thrust and strike-slip movement.[6]
Geology
The Brevard Fault Zone is a part of a much larger system of faults at the base of the Appalachian thrust sheet[1] that played a key role in uplifting the Appalachian Mountains. The extent of its role remains uncertain because most of the fault is buried beneath Quaternary sediment.[7] Many studies of the fault come from Grandfather Mountain in the Linville Fall Quadrangle,[8] which contains the exposed region that was first discovered by Arthur Keith. This region is only 1–3 km of its 700 km length.[7]
The Brevard Fault experienced multiple phases of deformation and minimal stratigraphic displacement.[3] The Brevard Fault Zone contains diverse lithologies, but it is primarily composed of mylonitic metagraywacke, schist, amphibolite, and gneiss[9] that underwent metamorphism 350–360 million years ago.[1] The Fault Zone is characterized by ductile behavior as indicated by the widespread presence of mylonitic and phyllonitic rocks.[1]
