Flysch: Beauty, Irregularity, & the Coast


Basque Country has many wonderful and special elements. It is well known to be rich in language and culture. It is also rich in environmental and geological phenomena. The flysch that frame the Basque coast are absolutely splendid. This geological treasure is on full display in Basque Country.

The flysch of Basque Country are a perfect example of how amazing the world is. What beauty the Earth creates over time is shown in these geological layers. The history of the planet is on display along the Bascque coast. These layers of rock upon rock look like pages in the book of Earth's biography.

Flysch, what is it?

Flysch is a type of sedimentary rock. It is formed through the alternating build up of materials like sandstone, shale and silt. This build up of material over time has led to the unique formation.

It is believed that flysch are formed in medium to deep ocean waters. The facies (the formation, composition and fossil content) of flysch are thought to have gained their features due to the turbidity of current moving along the surface. This occurs when the amount of particles in the ocean water is low and the water movement is gentle so as to not pull away and erode the existing surface but to bring new fragments of sand etc. and leave them there for future fusion. The coarser more jagged sections are due to a higher rate of turbidity.

Flysch is found when two confronting tectonic plates meet. The collision of these two plates pushes the oceanic plate downward while the continent plate rises above. As subduction continues, sediments of the oceanic plate are scraped off and add to what will eventually become the flysch. This process is often why flysch is so irregular in its sizes and shapes.

History of the Name

The name flysch was introduced to the scientific community by geologist Bernhard Suder in 1827. The word derives its meaning from the German word for flow; fliessen. Suder was of the belief that the creation of flysch had to do with sediment moved by rivers.

This theory resulted from Suder's work in the Alps. The notion that flysch was resulting from river flow was his original hypothesis. The realization that flysch was actually the result of tectonic plate shifting came later.

Flysch in Biscay

There are many places to see flysch in Biscay especially between Getxo and Plentzia. Barrika Hondartza and Playa de Muriola in the town of Barrika are two such beaches. You can hike between these two beaches in about twenty minutes.

Other beaches where flysch can be seen are Gorrondatxe Hondartza, Playa de Sopelana and Arrietara hondartza, to name a few. A paved trail called Paseo de la Galea connects these beaches. Read our article, Walk Above the Cliffs for a fuller description.

Flysch in Gipuzkoa

There are many places with flysch in Gipuzkoa. The most popular places are near the towns of Zumaia, Deba and Mutriku. Travelling between these towns to admire the ancient geological marine sites, you would take what is affectionately called The Flysch Route. This 13 km stretch of coastline is absolutely breathtaking.

We will be doing an in-depth look at The Flysch Route in a future article.

The Basque coast is one of the best places on Earth to marvel at flysch. These geological irregularities are as beautiful as they are mesmerizing. Flysch may have taken millions of years to develop but you are able to see them now. In Basque Country you'll have ample opportunity to study and awe at this spectacular phenomenon.

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