Basque Coast Getaria   Orio   Zarautz   Aia   Zumaia

Dune and wetlands of Santiago (Zumaia)

The River Urola rises in the foothills of Mount Aitzgorri and empties in the sea after winding across the valley of the same name for almost 60 kilometres. On its way, it forms large meanders between the towns of Iraeta and Zumaia. As it empties into the sea, a shoal of sand and silt forms on the right bank of the river. To the north of this shoal, opposite the Bay of Biscay, the dune begins to expand with the wetland area, which is sheltered by the bay.

The geological materials found here cover periods from the Late Cretaceous (around 75 million years ago), with limestone and marl, to the early Eocene (around 55 million years ago), with sandstone, clay and marly limestone. In the transition from the Cretaceous to the Tertiary period, limestone and marl are found with red layers, indicating the deposition of iron oxides.

The shoal of sand and silt formed during the Quaternary rests on the limestone and marl substrate of the Late Cretaceous. These are the sediments forming the beach and wetlands, reaching thicknesses of up to 30 metres.


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