Death Valley sand pits
I ran into strange dust pits when I was stationed at the NTC at Fort Irwin. I was driving along ( not on marked roads or trails) and my jeep would just sink three to five feet. These pits had a bottom you could feel, but the top layer looked like a powder. Ruin your whole day if you hit one doing about 40mph. The only way I could spot them was no rocks on the surface, just sort of a light area on the ground. If there saying that sleepy hollow is an impact crater, then no worries eh? Wouldn't the ground in the crater be more dense due to the impact compression?