Continental arcs are curved chains of volcanic islands or mountain ranges that form along the edges of continental plates. They occur when an oceanic plate subducts, or sinks, beneath a continental plate, leading to the melting of mantle material and the formation of magma. This process creates volcanic activity, resulting in the emergence of landforms such as volcanoes and mountains. These arcs are typically found at convergent plate boundaries, where tectonic plates collide. A well-known example of a continental arc is the Andes Mountains in South America, which formed as the Nazca Plate subducted beneath the South American Plate.