"Tom, what about upstream?"
It's a near vertical wall, Bob. No good options there, either. In early season when the streams are running high, Whitney, Wallace, Tyndall, Wright and the Kern can all be difficult to cross, but at least with all but Wright you have the option of looking up or down stream for better places. That is not the case with Wright Creek going up the HST from Kern Canyon. If you had to retreat, your only options would be to move upstream and take your chances with Tyndall, or head downstream and bushwhack up Whitney Creek out of the Kern Canyon. I've been down that route 3 times, and it is really steep. I wouldn't want to try ascending it, especially when I'd still have to get across the creek just after reaching the rim of the canyon, with the possibility of success unknown.