I live in Southern CA. For a number years I have been heading out towards edwards airforce base for motorcycle riding and all around tomfoolery. I believe in the response to the question “What causes the “washboard” effect on unpaved roads?” the responder hit the wrong nail on the head.
What we call simply “The Main Road” is a 20 mi dirt road between Randsburg and California city. This road is typically riddled with approximatley 4-6 inch bumps. The more traffic the more worn down these bumps get. This is what i believe the original question was getting at.
Rumor has it that it is likely from wind erosion, considering the location. Also from what I’ve heard (and experienced) of desert topsoil, the constant treading on the floor breaks up some sort of binding property that keeps it from eroding in general. Thus, it only appears on the roads.
I believe that what the responder was getting at was wupdy wups, typically found on motorcycle tracks where the ground has been worn to a sandy consistency. These are notoriously known as “wupty wups”, and that is exactly how they ride if you don’t know better. Those that do, ride relativley fast so that the motorcycle basically catches just the tops of the mounds (approx. 8’ top to top) and rocks under the rider who stands on the pegs.
Let me know if this clears anything up.