Land of the Lost (1974)

The Marshalls - widowed ranger father Rick, and his two children Will and Holly - are on an outdoor expedition like they have many times before. While rafting on this trip, an earthquake opens up a chasm resulting in them tumbling across some raging rapids and over an unknown waterfall. They end up alive but in a world unfamiliar to them, a world they will ultimately coin the Land of the Lost. It is inhabited by creatures some they have never seen or heard of, and some which no longer exist in the world they knew back home, creatures such as dinosaurs. They will find that some of these creatures are friendly, and some of them which they need to stay away from for their lives. As they eke out a life in this strange land, they try to understand what got them here so that they can make their way back home, that process which is fraught with its own dangers based on the unknowns of what is on the path to home. What they are also initially unaware of is that Rick's brother, fellow ranger Jack Marshall, is trying to trace their path to locate them.