A Question of Interpretation

The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth. Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms. It is often difficult to determine if wind eroded surface represent the youngest activity in a region. Wind eroded landforms can be covered by later materials and the exhumed long after they were initially formed. This image illustrates how difficult it can be to interpret the surface of Mars.