Polyfilla is quite good for craters, it's eco freindly and does not kill dinosaurs. ( I sometimes wonder why I say things like that)
How do you know about the dinosaurs?
It could be that the Yucatan peninsula was hit by a 50 Million tonne sack of polyfilla that fell out of some pikey aliens pick-up saucer.
Thanks for clearing that up for me DS, it is so reassuring to have a scientist in the bar who is willing to take on these types of questions and explain them to us laymen, can I buy you a gin and tonic?