Rockslide Details?

by David Kowalski
(Belle Mead, NJ (USA))

I've been studying the old stage coach roads into Yosemite Valley and would like to be able to date each of the rockslides which took out multiple sections of the Old Big Oak Flat Road (OBOFR) between the North Rim and the Valley Floor.

I've read a detailed Park Service report from 1991 which mentions 3 rock slides blocking the road but, from having hiked the road, I know there are now significantly more than that. Unless some of these seperate blockages are the result of single rockslides, it would seem that there were fewer slides blocking the road in 1991 than there are now so I would assume that at least some of these are recent (although all are since 1945 since the Old Road was still open to automobiles until then).

You mention on your Rockslides page that "519 rockfalls were recorded in Yosemite from 1857 to 2004." Do you know how I could get details of all these slides (I'm obviously most interested in the ones along the OBOFR but would be curious about the whole list)? I assume these are all documented in various Park Service reports but I've not been able to locate the information online.

Thanks,
David