[null and void]

Also a "dry" vs "wet" strike. No planetary steam cleaning.

[jpsb]

Now sure about the dry vrs wet, a mile thick ice cap sounds kinda wet.

My completely uninformed opiniun is that impacts are far more common and less deadly then is currently thought. Locally (couple thousand miles) very bad but not the cause of great extinctions. Plese do not ask my to back that up. I can't.