This book came to me from a source in Huntsville Alabama, who got it at a library book sale there. Remember Lost In Space? This looks to me a lot like a portion of a floorplan of an interdimensional craft from the future that got stuck here. this diagram portion shows the part that broke and would be readily evident to a person from that time, or someone who has seen other objects from a future. They would have had to have been picked up after the monument was built, I think, so they spent some time there. chaco canyon as messages to the future. Lost in space, but not really.