"If those little stones have remained in place in the sand through climate and weather changes without moving for almost 19000 years, I would be quite surprised."

Good point, but I would think that such thinking also tends to equally diminish the idea that the stones were placed there to target solstices and equinoxes...

One thing that does seem impervious to what you are saying, I would think, is the notion that NP was about tracking the stars in general, being out in the middle of nowhere. Too purposeful looking.