Can anybody help us explain what caused the phenomenon in this photograph (above)? It was taken on the Sands of Forvie nature reserve in north-east Scotland. The weather was dry, though there had been rain the day before. The photograph shows the lip and face of a small mobile sand dune. The slope of the dune face was approximately 45 degrees and the sand was dry at the time the photograph was taken. The image shows a section about 1 metre wide. The whole pattern extended about 20 metres.
Martyn and Margaret Gorman, Newburgh, Fife, UK