Splinter — Adam Roberts

Hector travels across America to visit his father on a ranch. He discovers that he has constructed a cult who await the impact of an asteroid. However, Hector is amazed when the section of Earth that the ranch is on suddenly breaks free from the rest of the planet during the collision. He struggles with his skepticism and acceptance of the fact that he is part of the remnants of the human race, on a splinter from the Earth.