About the 1923 USGS inscription
It’s pretty difficult to spot but keep your eyes peeled for a small sandbar with a big rock nestled on top of it underneath an overhang on river right. Pull over at the downstream end and look for a chipped inscription of USGS and a rock hammer. It’s somewhat faint and not much larger than a hand, but it’s there. This is from the 1923 USGS survey, known as the Birdseye Expedition.