The conventional view is that asteroids strike the earth at random locations, thereby randomly affecting various aspects of the earth' s evolution  One iconoclastic geophysicist claims instead that asteroids have struck the earth through a highly organized natural process  Cited as evidence is the unusual pattern of impact craters that form a halo-like swath across the Northern Hemisphere
There is a consensus that these craters appeared at the end of the Cretaceous period, followed by a mass extinction of much land and ocean life
Lumpy masses within the earth cause gravitational interactions with approaching asteroids that force them into specific orbits before impact.