THE GEOLOGY OF WESTERN NORTH CAROLINA: AN OVERVIEW

Flat Rock is located within the Blue Ridge Physiographic province of the Southern Appalachian Mountains. The geology of the surrounding area records over a billion years of Earth’s history and evidence of three Wilson Cycles.

Mesoproterozoic gneisses, the product of Grenville orogenesis are the oldest rocks in western North Carolina. Rifting of these gneisses in the Neoproterozoic deposited mixed volcaniclastic and sedimentary rocks within continental and oceanic basins along the new continental margin. Active rifting transformed into a passive continental margin during the Early Paleozoic, with widespread sedimentary deposition on both continental and oceanic crust.

Three major orogenic events affected the Grenville basement and younger cover sequences of western North Carolina during the Paleozoic: Taconic, Acadian/Neoacadian, and Alleghanian. The field trip will take place primarily within the Henderson Gneiss, a metamorphosed 450 Ma granitoid that is one of the largest plutonic bodies in the southeast. It was structurally emplaced during Neoacadian orogenesis as one of three stacked thrust sheets in the vicinity of Hickorynut Gorge, one of the best places to view multiple thrust sheets in North Carolina.

The region’s brittle structures, diabase dikes, and the Blue Ridge escarpment are evidence of the Mesozoic rifting of Pangea that created the Atlantic Ocean basin.