Your incorrect speculation re the obelisk is hampered by the fact that you don't know how that distant notch was formed and what else lay beyond it, on line. You get a pass on this one.
Here's another thing for you to consider re your backfilled mines. From my house, I can walk you to, oh, twenty backfilled mines in maybe an hour. Treasure trove wonderland? No. If these things were located on public land, the state of New Mexico backfilled them back in the 1980s as attractive nuisances and legal liabilities. You might look into this. It kinda ruins the excitement, yes, but then, I doubt you tried uncovering any of those you found anyway.
You might think I was being flippant about dogs, but if you're looking for the presence of prior human activities in uninhabited remote areas (mining, native American, graves, artifacts, et al), you might consider a four-legged exploration companion. I've had two that over the years have literally led me directly to dozens of such sites. They somehow have a sense about such things. Better than spending your money on dowsers or hanging around taking thousands of random photos - although, if you're fortunate, one day you might find a dowser who actually provides results. Hint: the only ones that can help you always do it for free.