Masthead: Kaweah Range

Sierra Nevada Earthquake History From Lichens
on Rockfall Blocks

William B. Bull

Emeritus Professor of Geosciences, University of Arizona

This article is in PDF format and is viewable with Adobe Reader which is a free download from Adobe. The article is in three parts to reduce download time. You may also view the entire article at once (recommended for high-speed connections).

Part 1: Abstract and Introduction (373 KB)

Part 2: Rockfall Processes (559 KB)

Part 3: Earthquake Generated Rockfalls (510 KB)

Entire Article (1.7 MB)

You may also download two other PDF articles giving more detail in identifying, measuring and calculating ages for Sierra lichen growth:

Bull, W. B., 2003a, Guide to Sierra Nevada lichenometry: in Tectonics, Climate Change, and Landscape Evolution in the southern Sierra Nevada, California: Greg Stock, editor; 2003 Pacific Cell Friends of the Pleistocene field trip, Sequoia and Kings Canyon, Appendix 8, p. 100-121. This article can be downloaded from (

Bull, W. B., 2003c, Choices and calibration of lichens for dating geomorphic processes in the Sierra Nevada of California: 7 p. This unpublished article can be downloaded from (

The full excerpt of John Muir's wild night in Yosemite Valley enjoying the Lone Pine earthquake and witnessing Eagle Rock:

“falling in thousands of the great boulders I had been studying so long, pouring to the valley floor in a free curve luminous from friction, making a terribly sublime and beautiful spectacle — an arc of fire fifteen hundred feet span, as true in form and as steady as a rainbow, in the midst of the stupendous roaring rock-storm. The sound was inconceivably deep and broad and earnest, as if the whole earth, like a living creature, had at last found a voice and were calling to her sister planets. It seemed to me that if all the thunder I ever heard were condensed into one roar it would not equal this rock roar at the birth of a mountain talus. Think, then, of the roar that arose to heaven when all the thousands of ancient canon taluses throughout the length and breadth of the range were simultaneously given birth.”

may be found at the Sierra Club John Muir Exhibit.




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