Chris Hague from the shop Mountain Intelligence in Leeds was at the crag when the fall occurred last Thursday:
"We were on the last pitch of Spartan Slab, when we heard a massive noise below. We looked down and there was a huge dust cloud and smell of cordite coming up the crag on the updraft."
Several tonnes of rock came away from one of the overlaps below the first belay of Spartan Slab, smashing directly on to the Coffin Stone - a large rock at the base of the crag that is a popular gearing up spot.
"It was a good job it wasn't a weekend," said Chris, "some of the rock landed directly on the Coffin Stone, some bounced over it, but what I also realised was lots of razor-sharp shards of rock showered the area with shrapnel."
The falling rock slid and bounced down the first pitch of the route The Long Reach, a classic E1 5b. "There's some flakes on that pitch that take small wires and slings," said Chris, "but some of them have been smashed off. I don't know if the grade has been affected."
Some climbers are speculating that after the long and unusually harsh winter, 2010 might be a year for unprecedented rockfall in the UK, and Chris Hague agrees. But he didn't hang around at the crag to see if anything else came off. After warning a pair of climbers approaching the cliff, he hot-footed it out of there.
"We had a super day, but yes, we only did one route - after the rockfall we didn't fancy another!"