The cave of time
You jump aboard and find yourself in a sealed chamber. The walls surrounding you remind you of the inside of a bathtub. It occurs to you that the beings who control this spaceship have some means of manipulating time. Could it be that the Cave of Time is their creation? As you are thinking these thoughts, you become increasingly drowsy. In a moment you are asleep.
You awaken in darkness, wondering if you may be traveling through space in the alien ship. There is light coming toward you from one direction and you get up and walk toward it. Then you realize you are looking through the opening of your cave. You hurry out and, to your joy, find Snake Canyon just as you remembered it. You are back in your own time.
It’s a long while before you feel like visiting Snake Canyon again. When you do, you find the opening to the Cave of Time has been covered over by a massive rock slide, and, you think to yourself that may be just as well.