Situated in the central part of the island, Água de Pau corresponds to a central volcanic complex and caldera that includes a large lake, punctuated by lava domes and a pumice cone.
On the flanks of the massif is the Ribeira Grande Graben, a tectonic structure oriented northwest-southeast, in addition to other regional fractures and radial faults that formed other scoria and pumice cones, or lava domes.

The stratigraphy of the Água de Pau Massif is complex, caused by a diverse volcanic activity over a period dated to 200,000 years.
The history of its geological features is divided into two groups.

The inferior group includes ancient material consisting of lava flows and trachyte pyroclastic deposits older than 40,000 years.

The superior group covers volcanic products dating from the last 40,000 years.
These consist of pyroclastic bombs and trachyte flows (pyroclastic and surge), mudflows and layered basalt rock, from phases associated with Plinian and sub-Plinian eruptions in the interior of the caldera.
This group is divided into five formations: Roída da Praia (between 34,000 and 8,000 years ago), Ribeira Chã (created from abrupt eruption 8–12000 years ago), Fogo A (also from an abrupt eruption some 5000 years ago), Lombadas (a complex eruption of Fogo B, C and D sites) and geological eruptions occurring in the last 3000 years.

Among the various deposits Fogo A, which dates to roughly 5000 years, corresponds a clear stratigraphy of the island of São Miguel.
The flanks of the massif are heavily eroded, with drainage confined to many valleys and gullies.
Situated in the central part of the island, Água de Pau corresponds to a central volcanic complex and caldera that includes a large lake, punctuated by lava domes and a pumice cone. On the flanks of the massif is the Ribeira Grande Graben, a tectonic structure oriented northwest-southeast, in addition to other regional fractures and radial faults that formed other scoria and pumice cones, or lava domes.
The stratigraphy of the Água de Pau Massif is complex, caused by a diverse volcanic activity over a period dated to 200,000 years. The history of its geological features is divided into two groups.
The inferior group includes ancient material consisting of lava flows and trachyte pyroclastic deposits older than 40,000 years.
The superior group covers volcanic products dating from the last 40,000 years. These consist of pyroclastic bombs and trachyte flows (pyroclastic and surge), mudflows and layered basalt rock, from phases associated with Plinian and sub-Plinian eruptions in the interior of the caldera. This group is divided into five formations: Roída da Praia (between 34,000 and 8,000 years ago), Ribeira Chã (created from abrupt eruption 8–12000 years ago), Fogo A (also from an abrupt eruption some 5000 years ago), Lombadas (a complex eruption of Fogo B, C and D sites) and geological eruptions occurring in the last 3000 years.
Among the various deposits Fogo A, which dates to roughly 5000 years, corresponds a clear stratigraphy of the island of São Miguel. The flanks of the massif are heavily eroded, with drainage confined to many valleys and gullies.
Água de Pau Massif