I forgot to mention that Geoff was standing right next to Doug when he slipped and went down the initial drop.
When he made it back up, Doug told me Geoff was pale and frightened... he said Geoff looked at him and said "Dad, that was really scary."
Now, Geoff normally would point and laugh and say "HA HA!" like Nelson on the Simpsons...
I have to say that I'm relieved that he reacted appropriately. That was really scary.