We Don't Need No Stinkin' Roads

One year, the family was on vacation (early 70s?) and somehow, we lost the road. I wish I could remember more details, but I will ask the rest of the family to chime in. I think it was in New Mexico. I am thinking it was not a year when we were pulling a camper. As we topped a hill, suddenly Dad started swerving to control the car because there was no road anymore. After we stopped, we found that we were between two large rocks, either of which might have disabled the car. OK, all, fill in the story.