Aeolian erosion of a fine-grained deposit is shown by the formation of a moat-and-tail structure around “Sponge Rock” at the Viking Lander 1 (VL-1) site. The scour orientation indicates that the erosive wind direction was from lower left to upper right. Note that the scour direction is roughly perpendicular to the axes of the pits caused by debris scoured by the landing rocket exhaust. Soil erodibility was assessed by monitoring the energy expended by the sample arm in digging trenches like those on the left side of the frame. The small, elongate pits in the foreground were caused by rock fragments kicked up by the landing retrorocket exhaust. The shadow of the meteorology boom is visible at the extreme left.
Frame number 11B169.