The grand, granite walls of Yosemite National Park, always in a state of peeling, dropped 20 tons of granite on Curry Village near a contested employee housing construction site Tuesday afternoon.

Park officials said the rockslide, sounding like distant thunder throughout the valley, left a white gash in the shape of a backwards "C" about 800 feet up the dark rock wall that backdrops the village, but caused no injuries or damage on the ground.

About 200 tourists staying in 102 cabins were moved to nearby lodges and had their money refunded, said Ken Karst, a spokesman for Delaware North Corporation Parks & Resorts.

Officials said the cabin evacuations were strictly precautionary.

"It's not like people ran screaming from cabins," said Yosemite spokeswoman Adrienne Freeman. "The rock fell into the zone designated for falling rock. It did not fall on the dormitory area. It did exactly what it was supposed to do."

The park service described the 3:45 p.m. slide as a nonevent in comparison to a 1999 slide that dropped 1.5 million tons of rock and darkened the valley with dust.

But opponents of putting employee housing near a rock fall area said they hoped the slide would provoke discussion before the dust settles.

Last year the employee housing project was the subject of a legal battle between the park service and an environmental organization which tried and failed to stop construction, arguing among other things that building in the area was a public safety threat.

"We're really concerned that it doesn't sound like we're saying, 'We told you so' in light of the slide," said Greg Adair of the Friends of Yosemite. "The park service is really in an untenable position. They've already made the environmental commitment. Seven or eight acres of pristine forest is already a construction site. But, still we're hopeful that they might change direction. We still think it's a dangerous place to put employees."

Ron Mackie, a retired ranger and longtime Yosemite observer, said the chances of another rockslide that could hit housing begs further conversation.

"I don't want to be a basher. I love our national parks, and there's a lot of tough issues," he said. "But this employee housing and rock fall debris problem might be at least worth talking about. This needs to be talked about."