Southeastern Section–55th Annual Meeting (23–24 March 2006)

Paper No. 1
Presentation Time: 1:35 PM


COSTELLO, John O., 16530 Hopewell Road, Alpharetta, GA 30004,

The Brevard schist was named by Arthur Keith over 100 years ago for the North Carolina city that lies in a narrow, continuous, northeast-to-southwest trending, belt of dark-colored, low-grade schist locally interlayered with lighter colored marble. He wrote that the marble occurrences extended at intervals within the schist, southwestward through South Carolina and far into Georgia. Subsequently, geologists recognized that with or without the marbles and despite the local presence of metamorphosed igneous rocks, Brevard zone lithostratigraphy and for the most part its conspicuous fabrics extend from Mt. Airy, North Carolina through South Carolina and Georgia and into Alabama where the zone is truncated by the Fall Line unconformity. Along most of its length, the Brevard zone is characterized by mylonitic rocks whose protoliths include both metasedimentary and metaigneous rocks. Mylonitic fabrics within the Brevard zone and the similarly oriented foliations and compositional layering in many less intensely deformed adjoining rocks has yielded a pronounced, consistently oriented “grain” through the southernmost Appalachian orogen. Differential weathering and erosion in the Brevard zone and adjoining rocks enhance this conspicuous lineament so that it is easily recognized on many topographic maps and satellite images. After 100 years of research and interpretations regarding the structure and geologic significance of the Brevard zone by numerous competent geologists, there is much yet to resolve. The purpose of this presentation is to summarize research on the geologic feature variously described as the Brevard zone, the Brevard fault zone, or the Brevard lineament.