Hi Joe: The rock doesn't conform to the sand, both the sand and the rock conform to the general shape of the crater. Ground under a crater is a shocked, shattered mess. But my guess is that the bedrock is where it was immediately after the impact and any sand formations are just random formations of the moment. The crater has probably been completely covered and uncovered hundreds of times by blowing sand, since it's formation. It would be interesting to know for sure if the crater formed before or after the H2O episodes; I'm guessing before, or water evidence would have been severely modified or eliminated by the impact. C. __________________________________ Do you Yahoo!? Yahoo! Small Business $15K Web Design Giveaway http://promotions.yahoo.com/design_giveaway/