Not another "ID this movie" thread

I don’t know why I’m trying to ID this movie I saw as a child, except for that sometimes things just bug you. The slim details are as follows.

Four(I think) boys are on a raft trip. They may have been Boy Scouts, not positive. They float through a mist on the river, and find they have gone back in time. Way back, to dinosaurs and such. This happens at least once, possibly twice more, and each time they are in a further back geological period, ending up where there is no animal life to speak of. There is one more mist on the river, and they speculate on what would happen if they row through it, but they don’t. I think that somehow they get back to their own time, but I don’t remember the means by which it happens.

I would have seen this movie no later than 1967, because I’m positive I saw it in grade school. But I wouldn’t stake my life on it. I’ve tried searching with combinations of “Boy Scout”, “raft”, “Time travel”, and “mist”, but so far have come up empty. Can fellow Dopers help?

This soundsvaguely like what you’re talking about. It came out in 1955: Cesta do praveku. I have no idea why the foreign title. All is says is:

Read the Alternate Versions page on IMDb. This is a Czechoslovakian film that came out in 1955. In 1965, the American distributors shot some additional scenes with American actors (who looked sufficiently like the original actors) that were a prologue to the original film, so that in the American version the film starts with the boys seeing dinosaurs in a museum. They then dubbed the rest of the film into English.

I remember seeing this when it first came out in its American edition. It was hokey, but I liked it because it featured scenes from the American Museum of Natural History. The statue the boys stare at that supposedly sends them into the past is the shaman in the Haida Indian Canoe that still sits in the 77th Street Foyer. At the end, they walk around the planetarium machine at the NY Hayden Planetarium (which was recently demolished and rebuilt). The animation was passable.
Last Christmas I got a boxed set of dinosaur movies, of which this is one. But I haven’t opened it yet.

My video tape of this is titled Journey to the Beginning of Time.

Thanks to everyone who responded. As I said, I don’t know why I wanted to ID this movie, but, well, there it is. I appreciate the efforts you all made.