THRILLING STUFF from the Hanna-Barbera stable, in the GODZILLA vein. A family go boating on the Colorado river and are swept down in a whirlpool that takes them to a lost valley frozen in time and filled with reptiles and cavemen. Most episodes revolved around their surviving and attempts, with the help of the cave dwellers, to get back to the world they once knew. One episode featured the family constructing a windmill that was going to be able to, for some reason, attract the planes that had started flying near the valley. Anyway, Father Caveman got trapped under a log in the stream, the family have to abandon holding up the windmill in the high wind to save him, and the windmill duly collapses.