I forgot to tell you guys.....that just before the turn off to the NNM, and 20 miles west of Kayenta, Nip and I went under a covered conveyor belt that comes a couple miles out of the mtn to the south of Hwy 160.
I've been under that thing at least a half dozen times like you have, and never really gave it much of a thought. Well, I've learned that that is a 17 mile long conveyor from the Black Mesa coal Mine started about mid century of the 1900s.
It's the biggest coal deposit in the USA worth an estimate of a 100 billion bucks. The coal is railroaded to a power plants over around Page. Additionally there is a pipe line to run coal slury 275 miles to Laughlin NV for their power.
Imagine the Navajo Indians having that kind of mineral resources going for them. I bet our gov boys didn't know that coal was there when our government gave them that reservation.