The oldest island in the Azores, where volcanoes gave way to fossils

Countries & Cities · Published 30 September 2026 Swipe more like this →

In short: While most of the Azores is defined by recent volcanic activity, Santa Maria tells a different story. As the archipelago's oldest island, its landscape is a complex mosaic of ancient eruptions and sedimentary layers, preserving marine fossils that are unique to this corner of the Atlantic.

Geologically, Santa Maria is the eldest member of the Azores archipelago. It emerged during the Miocene, approximately 10 to 8 million years ago, with volcanic activity continuing through the Pliocene about 2 million years ago. This long history has resulted in a more mature geography than its neighbors, featuring larger sediment deposits and a landscape shaped by successive periods of sea rise and coastal erosion.

The island's stratigraphy reveals a rhythmic history of fire and water. Its base, the Cabrestantes Formation, likely formed through multiple submarine eruptions. This was followed by the Anjos Complex (8–5.5 million years ago) and the Touril Complex, where intermittent eruptions allowed sediments and fossils to accumulate around 5 million years ago. The intense Facho-Pico Alto Complex period (5–3 million years ago) contributed the island's higher peaks, including Pico Alto, which stands at 590 meters.

This unique geological makeup has left a distinct legacy. Unlike many other islands in the archipelago, Santa Maria contains significant marine fossil deposits, such as those found in Prainha and Lagoinhas, with mollusks dating from 2.7 million years to less than one million years old. These deposits even fueled a 19th-century lime industry. Today, the island is characterized by two distinct regions: an arid, dry clay plain in the west and more humid, vegetated hills in the east.

Human history on the island is equally layered. While Diogo de Silves likely found the island during his journey to Madeira in 1427, official Portuguese recognition was attributed to Gonçalo Velho Cabral in 1432. The island's settlement was organized by the Infante Henry the Navigator, following a colonization model successfully used in Madeira in 1425.

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