Tunnel Through Time

This is a science fiction story about what it would be like to go back 80 million years in time and see what the Earth was like then. A scientist has created a device that tunnels through time. The protagonist is his son, 17 year old Bob Miller. Bob and his father's friend, Doc Tom, and Doc Tom's son Pete volunteer for a time travel journey even though the device is not perfected. The time travelers wander through the Ice Age and other primitive surroundings, equipped with only the barest essentials. They have to rely on intelligence to survive and to escape imprisonment. They encounter dangerous prehistoric monsters and even face the possibility of never returning to the present.