Richardson was there

Sam, Bob Richardson tried to duplicate this photo and a print was published in Lind's Narrow Gauge Country (p. 45). Based on the caption Bob hiked down to the bottom of the Gorge in 1950, and I would guess from the way Bob's photo is framed that he had a copy of the Jackson photo with him and found the spot, or at least close. But it doesn't really answer your question because the top of Bob's photo does not extend as high as Jackson's and at least from the reproduction in the book I can't readily pick out where the track might or might not be. But at least he saw the location first hand, and perhaps if somebody asked him he might be able to recall what he saw. It would not surprise me that the issue you are raising might have been on his mind. I'm having lunch on Wednesday with Gordon Chappell, and will ask if he and Bob ever talked about the issue. Looks like a tough hike.