Slide 3 of 35
Notes:
The history of rockfalls in the Yosemite Valley has been studied extensively.
Yosemite is a natural rockslide laboratory as a result of its complex geologic history. Although more than 400 rockfalls have been documented within the Yosemite Valley, they have been extremely rare in the vicinity of Glacier Point in historic time until 1996. Since that time, numerous slides have occurred.
Because rockfall is a natural phenomenon, in areas having steep slopes, and it results from normal environmental conditions, we believe that any significant change in rockfall frequency at a given location indicates that some change in the environment has occurred.
The complete USGS open file report Rockfall Hazards in the Yosemite Valley may be seen at:
http://greenwood.cr.usgs.gov/pub/open-file-reports/ofr-98-0467/
