San Francisco  - For decades, tourists to the world famous scenic site of Yosemite have rested their weary heads in the rustic cabins of Curry Village in the heart of Yosemite Valley.

But the National Park Service said Friday it was closing at least one third of the cabins in the popular lodging complex because an unstable cliff has created the potential for frequent and potentially deadly rock falls.

Park officials said 233 of the 618 cabins will close permanently after the latest rock fall hit 17 cabins in October at a time when more than 150 youngsters were on field trips at the site.

"The National Park Service can no longer treat each rock fall as an isolated incident," the park service said in a statement Friday.

"Instead, we must look at the area comprehensively and recognize that geologic processes that have shaped Yosemite Valley since the last glaciers receded will continue to result in rock fall."

The park service said the closure will impact 157,500 overnight guests per year. (dpa)