First Advisor

Ansel Johnson

Date of Publication


Document Type


Degree Name

Master of Science (M.S.) in Geology






Geological mapping, Slopes (Soil mechanics), Rock slopes -- Siskiyou National Forest (Or. and Calif.), Geology -- Siskiyou National Forest (Or. and Calif.)



Physical Description

1 online resource (100 p.)


The line mapping method of Piteau and Martin (1977) was tested on two different rock type road cuts in the Siskiyou National Forest, and was found to be an efficient means of collecting geological data for rock slope stability analysis. The unbiased approach of this method calls for close scrutiny of the outcrops in question, covering more ground than other methods in less time. In turn, this close attention to every crack in the outcrop reveals more about the stability of the slope, and can reveal hidden hazards of rock fall.

The supportive systems for analyzing the data - stereonets and computer program packages of Watts (1986) - led to the discoveries of several potential plane and wedge failures which were not initially visible. Also revealed was the fairly stable condition of the massive wedge at Elk River, which appeared to be extremely hazardous.

Each potential failure was analyzed for its Factor of Safety under dry and water saturated conditions, and the cohesion necessary to maintain stability was reported.


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Persistent Identifier

v57-1.JPG (1817 kB)
Figure 25. Topographical map of Powers site

v57-2.JPG (1732 kB)
Figure 34. Topographical map of Elk River site

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