Southwest of Bordeaux, at the entrance to the Bay of Arcachon, there is a giant sand dune called Dune du Pilat.
The dune is created from sand that builds against the forest wall, just off the beach. The sand collects in front of the forest and when the tide is low, large amounts of sand from the exposed sand banks are blown up to build the dune higher and higher until it stands where it does now, about 360 feet tall and a 1/3 of a mile wide. It’s estimated that the dune was half as tall a hundred years ago and every year it retreats back from the beach and into the forest between 5 and 15 feet. The side of the dune facing the ocean is gradual, but the back side (the side you climb up) is a 35 degree drop off into the forest. For incredible aerial photos, see this article. The Dune seems benevolent enough but it’s consumed houses and is in the process of suffocating trees. Dunes can be so cruel.
France is a country of many large rivers with waters running from the mountains and glaciers of the Alps region and Massif Central down into the ocean. Bordeaux lies on two rivers, the Gironde and the Dordogne, both of which spill out near the city and into the ocean. These rivers, along with the Charente and Loire river networks, empty into the Atlantic Ocean, picking up sand and sediment as they cut their way through land and towards the sea, carrying this eroded sand into the ocean. The ocean, with a southwards current along Atlantic France, filters the sand and any excess is built up near the shore in the form of sand banks. On the shore Southwest of Bordeaux these sandbanks are quite large and when the tide goes out, the sand is lifted by the strong west winds and Dune du Pilat is formed. In this way, when you’ve climbed to the top of the dune, you’re standing on thousands of years of the sand and sediment of inland France, cut out and delivered to the sea and collected underneath your feet.
When you’re standing atop the dune you can see Cap Ferret on the opposite side of the Bay of Arcachon. Cap Ferret is a long thin strip of land jutting out into the sea.
As Molly and I sat and ate our lunch atop the Dune du Pilat, we imagined Cap Ferret to be a wild and isolated place so we decided to drive around the bay and out to the 30km headland to the point at the end. We parked the car and walked out, anticipating a beautiful sand beach, but found this instead.
Cap Ferret, like Dune du Pilat, is in a unique geographical position. It juts out into the ocean current while also being surrounded by numerous sand banks to the east and south. The sand banks, in addition to providing the material for the dune, also block water from entering the bay and so the water circles back and lands up against the opposite side of Cap Ferret. With the coastal current and the large tides going in and out of the narrow bay, very violent currents are created that slam against Cap Ferret from multiple directions. When trash ends up in the rivers across France it is delivered into the Atlantic current where it joins trash from elsewhere in the world. If the ocean has its way, some of this debris is emptied here on the beach.
We found the ocean empties it’s dead animals on the beach here as well, a startling sight to see.
The ocean, as we all know, is a powerful machine. Just as it moves and pushes out excess sand to create giant sand dunes, it also discards trash onto beaches like this one. Standing there on the beach and admiring the sublime and beautiful dune, you realize that the trash-strewn beach and the dune are intrinsically linked by the power of the ocean, though only one deserves that most elusive label of being truly natural.