Hello Bill and Welcome to the forums!!!
It is usually one's first impression of the Stone Maps that sticks. Not always, but way more often than not. My first impression was about the same as your appears to be. I was IMPRESSED!
Anyone who has ever tried to cut their initials into solid rock (and I have) knows well how hard it is to do, how long it takes to do it, and how terrible it looks when you are finished.
My first thought when I looked at the maps was... This was not the first time the person that made them had done stone engraving. He had all the right tools, and many years of experience using them.
Like yourself, the holes were one of the first things that caught my attention. THEY HAVE TO BE THERE TO PUT SOMETHING INTO.
We have a heart shaped stone that fits into the heart shaped cavity. There has to be something to fit into the other cut outs. I believe you are on the right track thinking of sighting pointers, but try as I have. I can't imagine any logical way to use them. My guess, is that they would be an aid
to anyone winding their way through the mountains towards the end of the trail, if he knew how to use them. However... I don't think they are absolutely necessary to achieve that goal, so I don't pay much attention to them. Except... The big one! A lot of work went into that one compared to the others. It is cut so deep that the amount of rock left in the bottom of the hole is less than 1/4 inch thick. The map maker wanted that hole there very badly, to go to all that trouble, and risk breaking the stone in the process.
Yes, as you said... "The beauty and complexity is apparent". Same as the quality of craftsmanship! They have proven to be an inspiration to some, and a nightmare to others. Personally, I have experienced BOTH!
The deeper you get into them, the more inspiring they become, and the bigger the nightmare gets.
Busca El Coazon my new friend. Hope you continue to enjoy the site and share your thoughts often.