re: Probably a dumb question
How would you expect anyone to positively know the true answer to dumb questions? There were no rocks to fling? Because the impact was caused by an ice ball? And there were no rocks in the surface? Or the impact zone was under water at the time of impact? The rocks, if any, were covered by a later sand storm caused by the wind created from the impact explosion? The impact occured in a sand dune.