Shutter ridges occur where the fault carries high ground on one side past low ground on the other. In this case, the Hayward fault in Oakland carries the rocky ridge toward the right, blocking the course of Temescal Creek (here dammed to form Lake Temescal at the site of a former sag pond) and forcing it to flow rightward to get around it. (The result is a stream offset.) On the far side, the stream continues toward San Francisco Bay along the route of the freeway. The motion of the barrier is like the shutter of an old-fashioned box camera, hence the name. Compare this picture to the stream offset picture, which is exactly analogous.