fangsheath -<br /><br />Does the image you posted appear to have small pits and depressions in the rock? It looks better to me inverted. Raw MI images are sometimes posted "upside down". <br /><br />The way I'm seeing it, the apparent pits and small depressions in the rock turn into sand sized particles lying on the surface or maybe small protrusions/grains in it. There are still some linear patterns, maybe due in part to aeolian action, or perhaps some is the rock itself.