From my very limited time out in the SW I came to the conclusion there is something about the place that compels folks to "spruce it up" a bit with whatever their vision of art may be. Occasionally in odd and remote places. Perhaps the artist of the monolith figured the harder it was to reach the better the chance it would remain in place throughout the ages. But with google earth few things remain secret for long. I'm somewhat surprised it was spotted in person before a google earth searcher found it.