Basque Coast Geopark

Located in the NW quadrant of Gipuzkoa (Fig. B1), the territory applying to become a member of the EGN constitutes an area of
great interest and scientific importance. In stratigraphic terms, it is mainly made up of sedimentary rocks, dating from the Upper
Triassic Period (215 million years, Ma) to the Middle Eocene Epoch (45 Ma). In the coastal zone, there is an almost unbroken
sequence more than 5,000-m thick, outlining around 60 Ma of the history of our planet.
From a tectonic point of view, this territory is located in the Western Pyrenees and its structures appear to be aligned NW-SE. It
basically represents the extension process that occurred when the Bay of Biscay opened up (Jurassic – Upper Cretaceous), and
the subsequent inversion and compression stages (Upper Cretaceous - Palaeogene), which culminated in the formation of the
Pyrenees. The sedimentation in the central parts of the marine basin is represented in the municipalities of Deba and Zumaia. The
opening process is represented by the shallow marine sedimentation (Urgonian reef limestones) during the Aptian-Albian, and
later, with the deepening of the whole area, it became turbidite sedimentation (flysch) from the Upper Albian (Black Flysch) up to
the Eocene (Eocene Flysch or Gipuzkoa Flysch). This lengthy deep-sea sedimentation record offers a wide variety of facies, which
contribute to the exceptional quality of the outcrops.
The zone includes one of the most complete and continuous marine facies sedimentary records from the Cretaceous and the
Cenozoic in the whole of Europe. It is a global point of reference for the Cretaceous-Tertiary and Palaeocene-Eocene boundaries.