Aerial Photo of Wallace Creek and San Andreas Fault
December 18, 2006
The San Andreas Fault in the Carrizo Plain (California) is a showcase of classic tectonic landforms. Here we see the famous offset in Wallace Creek. The creek runs out of the Temblor Range on the North American Plate from the upper right. When it hits the fault, it's diverted northwest along the trace. The Pacific Plate, in the foreground, carries the channel with it as it moves, and the creek goes along as well. The offset in the present drainage is about 100 yards (91 m), but further to the left we see the ancestral drainage that was abandoned about three thousand years ago when the creek cut its present channel. Note that the San Andreas Fault and plate boundary are evident as a line of low scarps (cliffs) running horizontally through the center of the picture.