Geodiversity

Santa Maria stands out for its rare and distinctive geological features. Located in the Eastern Group of the Azores, together with São Miguel and the Formigas Islets, it was the first island to emerge, be discovered, and be populated, constituting the true geological cradle of the Azores.
The island formed about 6 million years ago, initially emerging in the area now known as Baía dos Cabrestantes, where the Archipelago’s oldest rocks are found. Its geological evolution is the result of eight volcanological units, representing different phases of submarine and subaerial activity. The first of these units corresponds to the Cabrestantes Formation, marked by intense submarine volcanism. Over time, eruptive episodes alternated with periods of calm, during which extensive marine sediment deposits formed, some containing a significant fossil record — evidence of ancient coastlines and sea-level variations.
Among its most unique geological features are three elements that do not occur with the same expression on any other island in the Azores, namely vast outcrops of pillow lavas, typical of submarine volcanism, the presence of various types of consolidated sedimentary rocks, such as limestones, sandstones, argillites, and conglomerates, and a remarkable fossil content, visible in many of these deposits.
Thanks to its geological age and changes in sea level, Santa Maria preserves an exceptional collection of marine fossils, including bivalves, gastropods (shells), sea urchins, and shark teeth, often associated with submarine volcanic formations. One of the most emblematic examples is the Pedreira do Campo, where marine fossils occur alongside pillow lava about 90 meters above sea level, revealing ancient oceanic landscapes that are now elevated.
All this stratigraphic and paleontological wealth makes Santa Maria a truly unique island: an open-air natural museum, whose geodiversity is unique in the Azores and of great scientific, educational, heritage, and tourist relevance.