The MSL Oct 4 telecon dwelt on the plans for the next couple of weeks at the Rocknest site to scoop material from a "sandbox" there. The sampling system first needs to be purged and cleaned of contaminants by doing a number of trial runs through it. The process will be more closely monitored initially to verify the proper functioning of the system. The caption for the conference image with the wheel impression on one of the drifts refers to it as a ripple. The Sol 58 MAHLI close-ups shows that the ripples consist of a crusty coarse grain layer resting on top of a more sandy one. The coarser grains may be saltation particles.
Supplemental (Oct 5): A zastryga, Russian заструга, is an inanimate object. It is fixed in place. There are other things like bow waves that are relatively fixed in place that fit in a more general class with similar attributes. Tags may be useful in identifying them.