Flores is the fourth oldest island of the Azores, with approximately 2.16 million years, and reaches its maximum height of 911 metres in the volcanic cone of Morro Alto.
As well as the neighbouring island of Corvo, the Mid-Atlantic Ridge separates Flores from the rest of the Archipelago, being these islands located in the North-American lithospheric plate.
Regarding the volcanism, it is important to mention the existence of an active volcanic system, the Lagoas Volcanic System. It includes the central plateau and the most recent volcanic activity recorded on the island, which began about 4000 years ago, after a prolonged period of inactivity of about 200 thousand years. The most recent eruptions occurred 3000 years ago.
Geologically, on this island exists the greater quantity and diversity of maars, which correspond to monogenetic volcanos. The maars are associated with hydromagmatic activity, resulting from the interaction between rising magma and the water on the overlying rocks, from which form explosion craters “embedded” on the surrounding areas, being most of them occupied by lagoons, such as the Lagoa Seca, Lagoa Comprida and Lagoa Funda.