Ultramafites in the Piedmont of North Carolina and South Carolina occur mainly in four types of bodies. (1) In many parts of the Inner Piedmont, small pods and lenses of Alpine-type altered dunite and peridotite are typically less than 200 m long, and their emplacement predates the main regional deformation and metamorphism. (2) In the south-central Inner Piedmont of South Carolina, more than 100 bodies of potassic ultramafic rocks occur in an area of several hundred square kilometers; the bodies are probably metamorphosed lamproites. (3) In the western Charlotte and Kings Mountain belts, peridotite, clinopyroxenite, and hornblende-bearing ultramafites are gradational into gabbroic rocks in large complexes that extend over tens of square kilometers; the ultramafites are probably cumulates formed in the roots of a calc-alkaline magmatic arc. (4) Several occurrences of ultramafic and related rocks interpreted to be dismembered ophiolites or ophiolitic mélanges are located near the Inner Piedmont–Kings Mountain belt boundary, on the flanks of the Raleigh belt, and in the Kiokee belt.

Abstract This publication consists of 5 chapters and resulted from the need to incorporate most of the COCORP southern Appalachian seismic reflection data and interpretations into a single work. Presented are ideas and models which are not only internally consistent, but also are consistent with what is known about the major geological and geophysical features.