Thanks, Walloon. for the suggestion. I’ll look for a copy of that but the shadow of a person thru an arch is not what I was looking for. I just ordered a bunch of oldies from Nina’s Discount Oldies at $5/each dvd (huge catalog). *Mckenna’s Gold * is too recent and too hued, but I’ll try that for Julie, too.
While we’re on the topic of other presentations of the general idea, there are historical precedents for the general idea. You might Google up Anasazi sun serpents or sun daggers. Except there, the location of interest is marked very clearly (by a spiral, symbol of the Sun, chipped or painted into the rock), and the purpose is to tell you a when, not a where: When the serpent reaches the center of the sun symbol, it’s Vernal Equinox, or the like. This could be valuable for an agricultural society, to track when to plant and harvest various crops.
Another possibility is that it was an episode of a B/W television western from the '50s like Rawhide, Wagon Train, or Death Valley Days.