Portuguese village preserves traces of ancient ocean

The site’s rock layers still show marks left by underwater currents, while the surrounding formation contains plant impressions and fossils of marine life.

The rocks at Vale Fuzeiros belong to the Brejeira Formation, which dates from between 318 and 307 million years ago. The Geopark says the area’s older rocks, found across the Algarve’s hills, can date back as far as 345 million years.

Ancient seabed

At the time, sand and mud were carried down the slopes of the Rheic Ocean by dense underwater flows known as turbidity currents. As each flow reached flatter ground and slowed, it dropped the heavier material first, followed by finer sediment. Repeated over millions of years, these deposits formed alternating layers of greywacke and fine-grained rock.

Some of those layers can still be seen at Vale Fuzeiros, including erosion marks at the base of the greywacke and impressions left by plants swept into the sea. The Geopark also records fossils of goniatites in the Brejeira Formation. These extinct marine molluscs had coiled shells and offer further evidence of the deep-water environment that once existed here.

Geological history

The Rheic Ocean eventually closed as the continents of Euramerica and Gondwana moved towards one another and collided. The collision helped form the supercontinent Pangaea and pushed the seabed deposits into the Variscan mountain belt. The Geopark says the ancient rocks were folded and fractured by these forces; traces of those changes remain in the region’s geology.

Today, the site offers a glimpse of an Algarve that existed long before its present coastline and towns formed. Its rocks tell the story of an ancient seabed, the currents that crossed it and the geological forces that later transformed it into part of the region’s uplands.