Canon 7D, EF 70-200mm f2.8L IS with 1.4X extender @ 280mm, f/11, 1/90 sec, ISO 200
This was one of Chuck’s stops. He even put down his tripod to take an image. What caught my eye was the contrast between the smooth dune face and the ripples on the down hill side. I also liked the “scallops” on the dune’s edge.