Regarding your first case, Glen, that is correct, I believe, and Roger has confirmed it with his greater expertise. As to your second, and rather fanciful, scenario, there I wouldn't just be rememberin', I'd be guessin'. I would imagine such a thing never happens except in the case of a small, local cavern. And that cavern would be filled with a fluid, which would make the collapse of the cavern roof rather more gentle than otherwise. I suspect you're correct that at least the upper hemisphere of the beach ball would be all white.

Michael F. Williams
Arroyo Grande, CA USA