The massive Pilat sand dune that devours trees and houses

Dune systems are often protected areas because of their high ecological and often tourist value. There are many, and some well known. But, without a doubt, the most singular of all is the one that can be found in La Teste-de-Buch, on the coast of Aquitaine, in the southwest of France: the Great Dune of Pilat. Yes, in the singular because it is not about dunes; it is only one. Giant.

Can you imagine a dune the size of a large beach? A mass of sand that covers 87 hectares and reaches a height of more than a hundred metres? A gigantic mobile hill, in short, that advances from 3 to 4 metres a year from the seashore inland, having already eaten half a kilometre of trees that make up the forest of the Natural Park of the Landes de Gascogne, transferring 60 million cubic metres.

This singular phenomenon is natural, although with some human contribution. Its origin is believed to date back thousands of years, although its current manifestation is more recent, from the 18th century. It was then that a sandbank from the sea began to accumulate and, to halt its advance, pines were planted (one hectare of pines can absorb 45 tons of water daily) along the coastline, so that they served as a barrier. At first, the solution was a success and the sand slowed down, but in return, it began to deposit on itself, growing in height.

Paradoxically, a new valuable ecosystem has appeared and is therefore protected by law by the French state as Grand Site National along with the 6,288 hectares of forest and the Arguin sandbank that protects it from the waves. Not only does it have ecological value; up to a million and a half people visit it annually (France’s second natural destination after Mount Saint-Michel), with the consequent impact on the local economy. Because it’s quite a spectacle to see that 40º inclination dune -accompanied by other smaller ones- which has the record of being the largest in Europe with its 2.7 kilometers long by 500 meters wide.

According to expert calculations, at the current rate of progression the sand will invade the Biscarrose road and the neighbouring campsite by 2045, as it did with several houses decades ago. It is not very clear because, given the system of development it undergoes -erosion by one extreme and feedback by the other at the same time – the movement is not regular, so that in certain periods it goes fast and in others it slows down.

In any case, it is possible that at some point it will cease to be something unique because in the southern part of the region, near Gaillouneys, the formation of a new dune has been detected which, in its youth, is even more active.