San Andreas Fault, Carrizo Plain

The stretch of the San Andreas Fault crossing the Carrizo Plain in central California is one of the clearest surface expressions anywhere of an active transform fault. The San Andreas marks the boundary where the Pacific and North American tectonic plates slide horizontally past one another, and across the Carrizo Plain this strike-slip motion has visibly offset stream channels and ridgelines by tens of meters, producing a textbook series of linear fault scarps, small enclosed sag ponds and sharply deflected drainages along the fault trace. The plain has experienced significant rupture during major historical earthquakes, including the 1857 Fort Tejon earthquake, and its clear, largely undeveloped exposure of fault-related landforms has made it one of the most studied sections of the fault by geologists.