This photo provided by the National Park Service shows a  plume of dust at Yosemite National park after a rock slide Wednesday, Aug. 26, 2009.
This photo provided by the National Park Service shows a plume of dust at Yosemite National park after a rock slide Wednesday, Aug. 26, 2009. Erik Skindrud National Park Service,
This photo provided by the National Park Service shows a plume of dust at Yosemite National park after a rock slide Wednesday, Aug. 26, 2009. Erik Skindrud National Park Service,