Thanks.
" Have you read Hancock's book about Mars?
No, what is the title?
He pulls together quite a bit of evidence that Mars took a major asteroid hit and suggests this could have happened as recently as 20k years ago. There's also a lot on meteor hits on Earth, with possible connections to the collapse of civilizations. As usual, Hancock overstates his case somewhat, and he wastes a couple of chapters speculating about the "face on Mars" but it's an interesting read.