Nestled at the entrance of the Arcachon Basin, the Dune of Pilat has over 4,000 years of history behind its creation. Its formation occurred in five stages. This immense sand mountain is the tallest dune in all of Europe. If you spend your vacation in the Arcachon Basin or at a campsite near the Dune of Pilat and decide to climb it, impress your friends by explaining the dune's formation in detail. Learn everything you need to know before climbing the dune.
A Story of Paleosols
On the western face of the dune, you’ll find a succession of layers of sand and remnants of black organic matter. These are known as paleosols, remnants of vegetation buried under layers of sand. The dune is composed of four paleosols, each marking a stage in the formation of this iconic tourist site.
The First Paleosol
Located on the alios, the first compacted sand layer, the dune's initial paleosol formed around 3,500 BCE. During the last glacial period, the climate was cold and dry. The area where the dune formed was covered with a forest of vegetation adapted to low temperatures, such as pine trees. Coastal winds caused sand to cover this initial forest layer, transforming it into Paleosol 1.
The Second Paleosol
Between 2 and 5 meters above the beach, Paleosol 2 resulted from the burial of another forest. Similar to the first, this forest was covered in sand between 2,000 and 500 BCE. A now-dry pond formed at the base of the dunes, where traces of microalgae can still be found. Archaeological evidence from the site indicates that by 900 BCE, humans had already colonized this coastal area.
The Third Paleosol
At a height of around 20 to 40 meters, the third paleosol layer is known as the "soil with kitchen debris." This name comes from the accumulated remains of oyster shells, clams, cockles, and more. This layer, dated to the Middle Ages during the 16th century, coincides with a period when the climate became slightly warmer and more humid.
The Fourth Paleosol
Between the 18th and 19th centuries, stronger winds brought more sand to the coastline, creating the final and highest dune layer. This new dune, reaching up to 100 meters in height, formed above the third paleosol. It is also known as the "modern dune" or "gravel dune." However, the advancing sand posed a threat to the Landes coastline. As a result, under Napoleon III, a campaign was launched to plant pine seedlings to stabilize the dune. The last paleosol layer corresponds to a cultivated forest that was buried as the sand advanced toward the coast. This new dune defines the current surface of the Dune of Pilat.