Nice tour, Phil.
I'd feel more confident about no further disturbance idea if they hadn't left those cairns to mark the spot. But what can you do.
Ironically, since Collin Fletcher first hiked the canyon end to end (as chronicled in the 1968 The Man Who Walked Through Time), Grand Canyon National Park has become the most visited river corrider in America. And yet, we know little more about it than we did when he made his epic walk. So it's good to know there is some work being done to uncover the richness of hits human past.