The full image has a field of traverse dunes on the left and barchan dunes on the right with a transition zone inbetween. Transverse dunes are oriented perpendicular to the prevailing wind direction. These dunes are comparable in size to the largest dunes found on the Earth. Local dust storms are relatively common on Mars. This storm is several hundreds of kilometers in extent and is located near the edge of the south polar cap.
Some local storms grow larger, others die out.
This image shows the Face on Mars that imaginative writers have cited as evidence for intelligent life on Mars. It is more likely that this hill, in the northern plains, has been eroded by the wind to give it a face like appearance. 23,460 A. Hall 1877 References Beatty, J. K. and A. Chaikin, eds. The New Solar System . Sky Publishing, 3rd Edition, 1990.