NASA Mars Odyssey THEMIS Image: Yardangs in Gusev

Image Context:


Context image credit: NASA/Mars Orbiter Laser Altimeter (MOLA) Team
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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.

Just above the sand dunes in this image are

multiple linear ridges. These ridges are yardangs. On

Earth yardangs are found in desert regions such as the

Gobi Desert of Mongolia. These features are formed by long-term

unidirectional winds in areas of partially or poorly

indurated materials (such as loess, flash flood deposits,

and soils). The wind erosion is cutting the trough between

the ridges – steadily deepening and widening the space.

Erosion rates on Earth have been measured at ~4mm/year of

removed material.

For more information on terrestrial yardangs see:

“Wind erosion research in China: Past, present and future”,

Shi Peijun, Keynote paper of the 12th International Soil

Conservation Organizaion Conference, 2002, Beijing, China.