Pre‐Triassic volcanic rocks of the southern Appalachians

Volcanic rocks occur from Pennsylvania to Alabama in the Piedmont Plateau, Blue Ridge Area, and the Great Valley. They include volcanics of pre‐Cambrian, Cambrian, and Middle Ordovician age. The most abundant types are basalt, andesite, rhyollte flows, tuffs, ash‐beds, and bentonite. The paper will discuss the types of volcanics In the different areas, their metamorphism, the relations of volcanics to the adjoining sedimentary and igneous rocks, and the facts on which their age is based.