Medusae Fossae Formation - Yardangs

Yardangs

The surface of the formation has been eroded by the wind into a series of linear ridges called yardangs. These ridges generally point in direction of the prevailing winds that carved them, and demonstrate the erosive power of martian winds. The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Layers are seen in parts of the formation. A resistant caprock on the top of yardangs has been observed in Viking, Mars Global Surveyor, and HiRISE photos. Images from spacecraft show that they have different degrees of hardness probably because of significant variations in the physical properties, composition, particle size, and/or cementation. Very few impact craters are visible throughout the area so the surface is relatively young.

• Medusae Fossae Formation as seen with Mars Odyssey's THEMIS. Notice elongated formations called yardangs.

• Medusae Fossae Formation as seen with HiRISE. Image is located in the Aeolis quadrangle.

• Yardangs in the Medusae Fossae formation, as seen by HiRISE under HiWish program. Location is the Amazonis quadrangle.

• Yardangs in Medusae Fossae Formation with caprock labeled, as seen by HiRISE. Location is Aeolis quadrangle.