7/6/15 - A significant section of the Regular Northwest Face route on Half Dome has fallen off, likely making the route unclimbable in its current condition. The large ledge at the end of Pitch 11, the traverse at the start of Pitch 12, and the bottom of the chimney pitches in the middle of Pitch 12 have disappeared. It's not known exactly when the rockfall occurred.
According to a post on Supertopo, a party attempting the route on July 5 had to retreat because they were unable to reach the bolt anchor in the wall above the former Pitch 11 belay ledge. It appears that there is no way to reach the chimneys of Pitches 12 to 15 without difficult, unprotected free or aid climbing, until climbers discover a new variation or add fixed protection to make the traverse possible. It's not clear who would create this new variation or how a decision would be made on "fixing" one of the world's most historic routes.
The Regular Northwest Face of Half Dome was a pioneering big-wall climb, first completed in 1957. The route is normally climbed today at 5.9 C1 with one bivouac, though it is also frequently climbed in a day and it has gone free at 5.12.
Half Dome is a classic example of an exfoliation dome, a granite dome created when plates formed along joints in the rock successively peel away, like the layers of an onion.
"I am sure that one way or another it will get restored to climbable shape," said big-wall expert Dave Allfrey. "Maybe it is just a question of how many bolts it will take. It is wild because I was just up there on June 10, and we retreated after some pretty sizable rockfall came right off the Visor in the late evening, following a thunderstorm a few hours prior.
"Thank god this didn't happen that day—there were 14 people at the base," Allfrey added. "It really is amazing that nobody got hurt or killed. It could have been so bad."
Roger Putnam, a climber and geologist who climbed the Regular Northwest Face on June 22, warned that more rockfall is likely in this area. "I see that as a possible progressing failure up an exfoliation slab," he said. "Often, when you see rockfalls coming from underneath a roof at the base of an exfoliation slab, more will follow. I hope nobody goes up there for quite a while."