Extintion question....

[Alien4240@aol.com]

I recently read the book T. rex adn the Crater of Doom by walter Alvzrez, 
1997. It was very interesting and sort of got me looking at extintion as a 
possible concentration. Anyway, I was wondering since the book doesn't make 
this too clear: I know they're certain a comet/meteor landed on/by the 
Yucatan Peninsula but are they sure that this one is what caused the K-T 
extintion, or is this still just one theory? I thought it was the reason for 
the extintion for a while but then I think I heard about a strike somewhere 
up by the Artic Circle above Europe, but I'm not sure. Thanks.


                                                                                
                                                        ~Matt