That left facing dihedral right in the middle of the sunny bit looks nice... Too bad we can't see it from the other angle, who knows what size crack it holds? Perfect fingers? Bottomed out seam? Heinous offwidth? Lets bushwack through the poison oak and find out! :)
Also, you did mean upstream, right? So you were backpacking on the JMT when you saw this?
Not in the Platte! This mystery dome is about twenty miles up the Merced River from Yosemite. We found it during an epic backpack from Mammoth to Yosemite. I put a picture here thinking that those who like hiking heavy loads into Lost Creek might be interested in this golden giant. Very sunny, so not a good summer expedition. Way past Merced Lake, where the plane full of weed crashed in the early 1970s. Maybe even a mile past Washburn lake. I didn't take good photo notes.
Has it has been climbed? There are no journal reports, and I scanned it with binoculars, finding no slings. In my opinion, it should be rappel descended to avoid a heinous looking gully/bushwack descent. Also, in my opinion it should be climbed and hand drilled (wilderness rules) by someone else. Please email me when done, or if you need help.