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.

He and his team then visited the Qaidam Basin to collect more information about the yardangs , the history of wind erosion and the dust.

In addition, the winds sculpt the yardangs (streamlined wind-rocks) of Lob Nor and the Qinghai Nanshan.

The findings suggest that the linear dunes are most likely of erosional origin similar to yardangs with orientations controlled by strikes of joints.

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.