With 21 islands, the archipelago of Fernando de Noronha is located on a volcano with a base of 74 kilometres in diameter and 1,280 metres deep. Extinct for more than 20,000 years, the submerged volcanic crater is part of a chain of mountains in the Atlantic part of the South American plate. The oldest volcanic rocks of the archipelago are about 12 million years old and the landscapes that exist today in Noronha are the result of periods of intense volcanic eruption, which occurred with explosions and lava emission, along with the occurrence of sediment erosion.