Costa Quebrada Geopark
Discover the Global Geosite
A land that holds the secrets of the Earth and humanity
The Costa Quebrada UNESCO Global Geopark, designated as such in 2023, is one of those exceptional natural gems. For decades, this valuable natural resource remained hidden behind the beauty of its cliffs, coves, and golden-sand beaches.
It is a living, inhabited landscape where the geology has been sculpted over millions of years by the titanic forces of the Cantabrian Sea. Today, both residents and visitors enjoy this environment, with its vibrant cultural heritage, where the Earth’s history takes center stage.
This geopark is a true natural laboratory for understanding the geological processes that have shaped our planet over the last 120 million years. The interaction between rock layers and the forces of the sea has created a spectacular array of coastal landforms: cliffs, arches, islets, coves, beaches, tombolos, dunes, and estuaries. These outcrops reveal fossils of ancient tropical reefs, prehistoric beaches, and petrified ecosystems—all bearing witness to events such as continental collisions, climate change, and mass extinctions.
The stretch between San Juan de la Canal and the Marisma de Miengo is listed in the Global Geosites catalog as one of the world’s most significant geological sites, under the name “Liencres Dunes and Costa Quebrada Coastline.”
Costa Quebrada, in addition to showcasing an extraordinarily rich and attractive array of coastal landforms within a small area, clearly demonstrates how the coastal landscape is shaped and allows us to reconstruct its evolution over time.
This Global Geosite is primarily of geomorphological interest and is included in the inventory published by the IGME under Geosite code CB010, as well as in the Geological Context of International Significance (Law 42/2007): Coasts of the Iberian Peninsula. Its inclusion is due to its importance in illustrating the evolution of a cliff coastline undergoing erosional retreat.
In the first phase, the waves exploit a small fracture and create a breach in the outer barrier of hard limestone. Once through it, the water rapidly erodes the soft materials behind it from below, causing the ground to be undermined and collapse (Predondo Sinkhole).
In Phase 2, several erosion pits merge due to the action of the sea. A narrow abrasion platform forms (a flat corridor carved into the soft marl), which remains partially protected by the outer limestone wall. The waves dismantle this outer wall along the network of fractures, leaving isolated spires and ridges. El Madero is a good example of this stage.
Phase 3: Erosion has made significant inroads into the Turonian marls. As the soft materials are worn away and cleared away, a vast and striking abrasion platform is formed, leaving the area completely exposed (La Arnía platform).
Finally, in Phase 4, the inlets expand laterally, always seeking out the least resistant rocks (Portío Inlet). The complete erosion of these soft layers leaves a row of residual islets isolated in the sea. The famous Urros stand as witnesses to the ancient coastline, formed from the hard limestones of the Aptian.