I started reading a book about a man named Clarke (last name) and he was in an RV in Alaska. He was in the US military, and the RV was set up for a hunting trip. An experiment in the base accidently sent part of the parking lot back to prehistoric era, near the Ice age. He was helping a clan of people. I can't remember the name or the author. Google was no help. Can someone please help? Thank you in advance.