Yardangs are streamlined hills carved from bedrock or any consolidated or semi-consolidated material by abrasive dust and sand particles carried in the wind.
The orientation of the yardangs leads scientists to theorise that strong north-northeasterly winds (from the lower right in the image) both deposited the original sediments and then caused their subsequent erosion in a later drier period of martian history.
Much of the formation's terrain is covered with wind-sculpted hills called yardangs
, a sign that the exposed material erodes easily, says Watters.
Last but not least, the profile of the huyang, with its massive trunk, which is said to take a thousand years to grow, a thousand to die and yet another thousand to decompose once it has fallen, stamps its characteristic mark on the land both when it is alive--for example those incredible watery landscapes visible on the Tarim's middle reaches, recalling Louisiana bayous in the middle of the desert--and when it is dead and its tortured forms, like an army of skeletons, rise up among the dunes or yardangs
, where the shifting riverbed has given way to desert.
In addition, the winds sculpt the yardangs
(streamlined wind-rocks) of Lob Nor and the Qinghai Nanshan.
Scientists discovered miles-long, wind-scoured ridges called "yardangs" with the first Mars orbiter, Mariner 9, in the early 1970s.
"HiRISE is showing us just how interesting layers in yardangs are," Bridges observes.
The findings suggest that the linear dunes are most likely of erosional origin similar to yardangs
with orientations controlled by strikes of joints.
Then Kapp and his team went to the Qaidam Basin to collect more information about the yardangs
, the history of wind erosion and the dust.What we're proposing is that during the glacials, when it's colder and drier, there's severe wind erosion in the Qaidam basin and the dust gets blown out and deposited downwind in the Loess Plateau," Kapp said.