Normal, Thrust and Reverse Faults

• Cross-section of normal faults -- vertical roadcut exposing layers offset by two normal faults
• Scarp of normal fault -- created in 1969 Montana earthquake
• Aerial view of normal fault scarp -- fault offsets glacial moraines at mouth of McGee Cr
• Normal fault scarp -- ground photo of normal fault offsetting McGee Cr. glacial moraines by 75 ft
• Normal fault scarp -- aerial view of scarps on E side of Klamath Lake
• Normal fault scarp -- closer view of Klamath Lake scarp showing fresher surface
• Normal fault scarp -- close up of fresh portion of Klamath Lake scarp
• Normal fault scarp -- E side of Sierra Nevada
• Graben -- valley formed by downdrop along two normal faults that face each other. This one is quite young.
• Eroded normal fault scarp -- inactive scarp has been cut by streams to form triangular facets
• Eroded normal fault scarp -- inactive scarp has been cut by streams to form facets
• Thrust fault -- Dacite thrust over younger pyroclastic deposits; exposed in roadcut in Lake Co. CA
• School Road Fault (thrust) -- Aerial view of marine terrace offset by thrusting from NE to SW. House is on upper plate. McKinleyville, CA
• McKinleyville Fault (thrust) -- Aerial view of marine terrace offset by thrusting from NE to SW. Airport is on upper plate. McKinleyville, CA
• McKinleyville Fault cross-section -- fault zone exposed in coastal cliff west of airport, McKinleyville, CA. Note conjugate shears. Thrusting is from left to right.
• McKinleyville Fault detail -- Detail of offset in coastal cliff, showing overlap (shortening) of gravel layer

Strike-Slip Faults -- Physical evidence for inferring fault location and activity

• Offset sidewalk -- evidence for creep along San Andreas Fault in Hollister, CA
• Offset wall -- evidence for creep along San Andreas Fault in Hollister, CA
• Offset gullies -- evidence for movement along San Andreas Fault, Carrizo Plains
• Offset ridges -- evidence for movement along San Jacinto Fault near Hemet, CA
• Sag ponds and pinch-up ridges -- these mark the trace of the San Andreas Fault as it crosses the Carrizo Plains
• Sag pond -- small pond formed along trace of San Andreas fault -- suggests fault is active because such ponds typically are filled within a few thousand years if not rejuvenated by continued fault movement
• Line of sag ponds -- this line of ponds north of San Jose marks the trace of the San Andreas Fault
• Fault gouge -- brecciated (sheared and broken ) granite along the trace of the San Andreas. This material is weak and easily eroded.
• Linear fault valley -- the valley of the Garcia River in Mendocino Co. follows the weaker sheared rocks along the trace of the San Andreas Fault.
• Fault zones near San Francisco -- map showing the major branches of the San Andreas Fault south and east of San Francisco
• Linear fault valley -- the trace of the San Andreas on the San Francisco Peninsula is marked by a prominent linear valley eroded in the weaker sheared rocks along the fault.
• Linear fault valley -- aerial view NW along the San Andreas fault on the San Francisco Peninsula
• Linear fault valley -- another aerial view NW along the San Andreas on the San Francisco Peninsula
• A geological nightmare, or how to do everything wrong -- trace of San Andreas near Mussel Rocks south of San Francisco. Development is built directly across fault zone, partially on fill, partially on weak unconsolidated rocks near steep, landslide-prone cliff.
• Hayward Fault -- air photo showing trace of Hayward Fault through Berkeley
• Offset fence -- fence near Olema offset 2.5 m by 1906 earthquake on San Andreas
• Groundwater effects -- in this area near Palmdale, the San Andreas acts as a barrier to groundwater flow, causing a difference in vegetation density across the fault. The fault can easily be mapped on this basis.

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