|Here is the Grand Canyon confluence. Grand!|
To get here, it was necessary to park where you're not supposed to and hike in a couple miles through the forest to the canyon's edge. According to the GPS, the confluence turned out to be about three or four paces past the cliff's edge. It was a long drop.
I'm not that dedicated. Anyhow, given the military's Selective Availability policy, maybe the confluence is right at the edge.
On the way back to the road, I found an official Confluence Mandible:
I'm not sure it's actually a mandible. It won't matter if it isn't. It's still a Confluence Mandible.