Ripples

Wind ripples cover the upwind face of a dune behind Tin City, a fine pattern of parallel ridges running across the slope in a single direction. The ripples are small, around the width of a finger, set in close repetition. The wind that made them was the prevailing southerly that runs up the coast. The sand catches the early light low and from one side, throwing the ridges into shadow on their downwind face and bright on the upwind. Where a footprint or vehicle track has crossed the slope, the ripple pattern is broken; the rest of the field is unmarked. The dune itself drops away behind the ripple frame.

The Stockton Bight is the largest mobile coastal sand mass in the Southern Hemisphere, in the NPWS's wording. The dune field migrates approximately 4 m northward each year on the prevailing winds, but the surface ripples re-form much faster: any wind strong enough to move sand will rework the upper layer in a single afternoon. The ripples in this photograph belong to the day they were taken. They will be gone by the next strong southerly. The dunes themselves are slower: at the pace they move, a Tin City shack at the south end of the settlement has a generation or two before it has to deal with the sand catching up to it.