Sand Dune (Cape Verde)
A beautiful crescent shaped dune, photographed from the ridge. Two small children and their father are running, together, down the steep leeward face. When people ran down the dune in this way the sand used to hum. (I mention this for interest's sake; the massive dunes of the Namib desert do not hum when one runs down them, and so I assume that the phenomenon has something to do with the size or shape of the grains of sand.)
This dune was photographed in Boa Vista in the 1990s. At that time there were several very large dunes on the western coast of the island, but dunes are not static things - they move about at the whim of the wind - and the whole lot have long since marched into the sea.
Boa Vista, Cape Verde, West Africa