The Emporia 1:100,000-scale quadrangle straddles the Tidewater Fall Line in southern Virginia and includes a small part of northernmost North Carolina (fig. 1). Sediments of the coastal plain underlie the eastern three-fifths of this area. These sediments onlap crystalline basement rocks toward the west and dip gently to the east, reaching a maximum known thickness of 821 feet (ft) in the extreme southeastern part of the map area (fig. 2). The gentle eastward dip is disrupted in several areas due to faulting delineated during the course of mapping.