Itzurun

Below the town of Zumaia on the Basque coast, a short beach of sand and rock lies at the foot of near-vertical cliffs up to 150 metres high, made of thin layers of rock stacked like the pages of a book tipped on end. This is flysch: alternating beds of harder and softer sediment laid down on the deep seafloor and later tilted upright, so that the cliffs of Itzurun expose millions of years of Earth's history in a single sweep. The strata belong to a continuous run of rock that stretches for about 8 km along the coast between Deba and Zumaia, one of the longest continuous sedimentary sequences anywhere, and the area forms part of the Basque Coast UNESCO Global Geopark.

The rocks of Itzurun hold a special place in geology. The International Union of Geological Sciences chose the Zumaia section at this beach as the global reference point – the "golden spike" – for the base of two stages of the Paleocene epoch, the Selandian, about 61.6 million years ago, and the Thanetian, about 59.2 million years ago. Geologists anywhere in the world who want to define those boundaries compare their rocks with the layers exposed here. Ammonite fossils occur in the surrounding cliffs, and at low tide the stone platforms in front of the beach reveal the striped bedding in long ribs running out to sea.

The beach, also known as San Telmo after the small hermitage on the headland above it, is about 270 metres long and lies between the points of Marianton and Algorri, sheltered by its cliffs and open to strong Atlantic swell. Its dramatic scenery was used as a filming location for the television series Game of Thrones. Zumaia itself is a small Gipuzkoan town at the meeting of the Urola and Narrondo rivers, with a fishing tradition reaching back to a mariners' confraternity founded in 1610; the Algorri interpretation centre in the town presents the coast's geology.

Getting there

Itzurun Beach lies on the northern edge of Zumaia, within walking distance of the town centre; Zumaia station is on the Euskotren line between Bilbao and San Sebastián. Zarautz is about 8 km away. The nearest airport is San Sebastián Airport (EAS), about 39 km away.